VARIABLE GEOMETRY TURBINE ASSEMBLY
The present invention relates to a variable geometry turbine assembly. The present
invention relates to a variable geometry turbine assembly of a variable geometry
turbomachine and particularly, but not exclusively, of a variable geometry turbocharger.
The present invention also relates to an actuation mechanism for moving a movable
wall member of a variable geometry turbine.
Turbochargers are well known devices for supplying air to the intake of an internal
combustion engine at pressures above atmospheric pressure (boost pressures). A
conventional turbocharger essentially comprises an exhaust gas driven turbine wheel
mounted on a rotatable shaft within a turbine housing connected downstream of an
engine outlet manifold. Rotation of the turbine wheel rotates a compressor wheel
mounted on the other end of the shaft within a compressor housing. The compressor
wheel delivers compressed air to the engine intake manifold. The turbocharger shaft is
conventionally supported by journal and thrust bearings, including appropriate
lubricating systems, located within a central bearing housing connected between the
turbine and compressor wheel housings.
In known turbochargers, the turbine stage comprises a turbine chamber within which
the turbine wheel is mounted; an annular inlet passageway defined between facing
radial walls arranged around the turbine chamber; an inlet arranged around the inlet
passageway; and an outlet passageway extending from the turbine chamber. The
passageways and chambers communicate such that pressurised exhaust gas admitted
to the inlet chamber flows through the inlet passageway to the outlet passageway via
the turbine and rotates the turbine wheel. It is also known to improve turbine
performance by providing vanes, referred to as nozzle vanes, in the inlet passageway
so as to deflect gas flowing through the inlet passageway towards the direction of
rotation of the turbine wheel.
Turbines may be of a fixed or variable geometry type. Variable geometry turbines differ
from fixed geometry turbines in that the size of the inlet passageway can be varied to
optimise gas flow velocities over a range of mass flow rates so that the power output of
the turbine can be varied to suite varying engine demands. For instance, when the
volume of exhaust gas being delivered to the turbine is relatively low, the velocity of the
gas reaching the turbine wheel is maintained at a level which ensures efficient turbine
operation by reducing the size of the annular inlet passageway. Turbochargers
provided with a variable geometry turbine are referred to as variable geometry
turbochargers.
In one known type of variable geometry turbine an axially moveable wall member,
generally referred to as a "nozzle ring" defines one wall of the inlet passageway. The
position of the nozzle ring relative to a facing wall of the inlet passageway is adjustable
to control the axial width of the inlet passageway. Thus, for example, as gas flow
through the turbine decreases, the inlet passageway width may be decreased to
maintain gas velocity and optimise turbine output. The nozzle ring is provided with
vanes which extend into the inlet and through slots provided in a "shroud" defining the
facing wall of the inlet passageway to accommodate movement of the nozzle ring. The
vanes are at a fixed angle relative to the radius of the nozzle ring. A variable geometry
turbocharger including such a variable geometry turbine is for instance disclosed in US
5,868,552.
In different arrangements the nozzle ring is fixed and the shroud is axially moveable so
as to control the axial width of the inlet passageway.
In current variable geometry turbochargers the moveable wall member (i.e. the nozzle
ring or the shroud) is mounted on the end of push rods that are attached, at their other
end, to a rotating yoke pivoting in an arc about a cross shaft. The yoke is arranged
such that its rotation moves the push rods in the axial direction, so as to move the
moveable wall member in the axial direction.
The yoke and push rods are mounted internally to the bearing housing. In this case,
seals are required where the push rods pass through the bearing housing wall into the
turbine housing. These seals are relatively expensive and require water cooling, which
increases the complexity and cost of the variable geometry to the charger.
In an alternative arrangement, the push rods and the yoke are mounted in a cavity in
the turbine housing. This arrangement does not require the seals of the bearing
housing mounted arrangement. However, this arrangement is large and bulky in
nature to allow for the mounting of the moveable wall member, push rods, and yoke.
This results in a large overall turbine housing, which also increases its thermal inertia.
Furthermore, due to the large cavities required to house all of the moving components,
an increased pressure differential is experienced during filling and scavenging of the
exhaust gas in the housing.
It is one object of the present invention to obviate or mitigate the aforesaid
disadvantages. It is also an object of the present invention to provide for an improved
or alternative variable geometry turbine assembly. It is also an object of the present
invention to provide for an improved or alternative actuation mechanism for a movable
wall member of a variable geometry turbine assembly.
According to a first aspect of the invention there is provided a variable geometry turbine
assembly comprising:
a turbine wheel mounted within a turbine housing for rotation about a turbine
axis;
an annular inlet passageway extending radially inwards towards the turbine
wheel;
the annular inlet passageway being defined between a surface of a movable wall
member and a facing wall;
the movable wall member being movable in the axial direction so as to vary the
size of the annular inlet passageway,
and an actuation mechanism arranged to move the movable wall member axially
relative to the facing wall;
the actuation mechanism comprising:
a carrier member, the carrier member being movable in the axial direction and
coupled to the movable wall member such that as the carrier member is moved in
the axial direction, the moveable wall member is moved in the axial direction
a cam member provided with at least one formation;
the carrier member being coupled to at least one co-operating formation such
that as the at least one co-operating formation is moved in the axial direction, the
carrier member is moved in the axial direction, wherein one of the at least one
formation and the at least one co-operating formation is a radially extending
formation and the other defines a complimentary recess for receiving the radially
extending formation, the at least one formation or the at least one co-operating
formation extending in both the circumferential direction and the axial direction;
the actuation mechanism is arranged such that as the cam member is rotated
relative to the carrier member, the at least one formation and the at least one co
operating formation engage such that the at least one co-operating formation is
moved in the axial direction, thereby moving the carrier member in the axial
direction, and thereby moving the movable wall member in the axial direction so
as to vary the size of the inlet passageway;
the turbine assembly further comprising a nozzle ring having a plurality of
circumferentially distributed inlet vanes and an annular shroud provided with a
plurality of slots for receiving the inlet vanes of the nozzle ring as the shroud is
moved axially relative to the nozzle ring;
wherein the shroud comprises the movable wall member;
and the nozzle ring and shroud are mounted on the same axial side of the inlet
passageway.
This is advantageous in that it provides a relatively compact variable geometry turbine
arrangement. In addition, the cam member, carrier member and movable wall member
can be formed as a self-contained cartridge that is relatively compact and easy to
install.
Furthermore, the above arrangement does not require axial push rods to move the
moveable wall member and so does not require the sealing arrangement necessary
where push rods are used, which is relatively expensive, wears easily and requires
water cooling. Therefore the above arrangement is relatively inexpensive, durable and
compact.
It will be appreciated that where something is referred to as "radially extending" or
"extending in the radial direction", this refers to extending generally in the radial
direction (the radial direction relative to the turbine axis) and, unless otherwise stated,
is not to be interpreted as specifically requiring that it extends substantially parallel to
the radial direction.
Similarly, where something is referred to as "axially extending" or "extending in the
axial direction" this refers to extending generally in the axial direction (the direction of
the turbine axis) and, unless otherwise stated, is not to be interpreted as specifically
requiring that it extends substantially parallel to the axial direction.
Optionally the nozzle ring comprises an annular radially extending wall, the plurality of
circumferentially distributed inlet vanes extend axially inboard from an inboard surface
of the radially extending wall and the annular shroud comprises an annular radially
extending wall provided with said plurality of slots, wherein the radially extending wall
of the nozzle ring is mounted axially outboard of the radial wall of the shroud.
Optionally the variable geometry turbine assembly comprises a bearing housing
arranged to house at least one bearing that rotatably supports a shaft on which the
turbine wheel is mounted and the shroud and the nozzle ring are mounted on the same
axial side of the inlet passageway as the bearing housing.
Alternatively, the shroud and nozzle ring may be mounted on an opposite axial side of
the inlet passageway to the bearing housing. In this regard, the shroud and nozzle ring
may be mounted on the same axial side of the inlet passageway as the turbine
housing.
Optionally the nozzle ring is substantially fixed in the axial direction. In this regard, the
inlet vanes of the nozzle ring are disposed in the inlet passageway. The inlet vanes
may extend substantially across the width of the inlet passageway.
Optionally the nozzle ring is also movable in the axial direction, so as to vary the axial
extent of the inlet vanes in the inlet passageway.
Optionally the carrier member is annular. Optionally the carrier member extends in the
circumferential direction about the turbine axis.
Optionally the cam member and the carrier member axially overlap for at least one
axial position of the movable wall member.
Optionally the cam member is disposed radially outwardly of the movable wall member.
Alternatively, the cam member may be disposed radially inwardly of the movable wall
member.
Optionally the at least one formation and the at least one co-operating formation extend
in both the circumferential direction and the axial direction. Preferably only the at least
one formation or the at least one co-operating formation extends in both the
circumferential direction and the axial direction.
According to a second aspect of the invention there is provided a variable geometry
turbine assembly comprising:
a turbine wheel mounted within a turbine housing for rotation about a turbine
axis;
an annular inlet passageway extending radially inwards towards the turbine
wheel;
the annular inlet passageway being defined between a surface of a movable wall
member and a facing wall;
the movable wall member being movable in the axial direction so as to vary the
size of the annular inlet passageway,
and an actuation mechanism arranged to move the movable wall member axially
relative to the facing wall;
the actuation mechanism comprising:
an annular carrier member, the carrier member being movable in the axial
direction and coupled to the movable wall member such that as the carrier
member is moved in the axial direction, the moveable wall member is moved in
the axial direction
a cam member mounted for rotation about the turbine axis;
the cam member is provided with at least one formation;
the carrier member being coupled to at least one co-operating formation such
that as the at least one co-operating formation is moved in the axial direction, the
carrier member is moved in the axial direction, wherein one of the at least one
formation and the at least one co-operating formation is a radially extending
formation and the other defines a complimentary recess to receive the radially
extending formation, the at least one formation extending in both the
circumferential direction and the axial direction;
the actuation mechanism is arranged such that as the cam member is rotated,
the at least one formation and the at least one co-operating formation engage
such that the at least one co-operating formation is moved in the axial direction,
thereby moving the carrier member in the axial direction, and thereby moving the
movable wall member in the axial direction so as to vary the size of the inlet
passageway;
wherein the cam member and the carrier member axially overlap for at least one
axial position of the movable wall member.
This is advantageous in that it provides a relatively compact variable geometry turbine
arrangement. In addition, the cam member, carrier member and movable wall member
can be formed as a self-contained cartridge that is relatively compact and easy to
install.
Furthermore, the above arrangement does not require axial push rods to move the
moveable wall member and so does not require the sealing arrangement necessary
where push rods are used, which is relatively expensive, wears easily and requires
water cooling. Therefore the above arrangement is relatively inexpensive, durable and
compact.
Optionally the carrier member is annular. Optionally the carrier member extends in the
circumferential direction about the turbine axis. Optionally the carrier member
comprises an annular wall that extends in the circumferential direction about the turbine
axis.
Optionally the cam member and the carrier member axially overlap for a plurality of
axial positions of the movable wall member.
Optionally the turbine assembly further comprises a nozzle ring having a plurality of
circumferentially distributed inlet vanes and an annular shroud provided with a plurality
of slots for receiving the inlet vanes of the nozzle ring as the shroud is moved axially
relative to the nozzle ring.
The nozzle ring and shroud may be mounted on the same or different sides of the inlet
passageway. Where the shroud comprises the movable wall member, the nozzle ring
and shroud may be mounted on the same axial side of the inlet passageway.
Optionally the cam member is disposed radially outwardly of the movable wall member.
Alternatively, the cam member may be disposed radially inwardly of the movable wall
member.
According to a third aspect of the invention there is provided there is provided a
variable geometry turbine assembly comprising:
a turbine wheel mounted within a turbine housing for rotation about a turbine
axis;
an annular inlet passageway extending radially inwards towards the turbine
wheel;
the annular inlet passageway being defined between a surface of a movable wall
member and a facing wall;
the movable wall member being movable in the axial direction so as to vary the
size of the annular inlet passageway,
and an actuation mechanism arranged to move the movable wall member axially
relative to the facing wall;
the actuation mechanism comprising:
a carrier member, the carrier member being movable in the axial direction and
coupled to the movable wall member such that as the carrier member is moved in
the axial direction, the moveable wall member is moved in the axial direction
a cam member provided with at least one formation;
the carrier member being coupled to at least one co-operating formation such
that as the at least one co-operating formation is moved in the axial direction, the
carrier member is moved in the axial direction, wherein one of the at least one
formation and the at least one co-operating formation is a radially extending
formation and the other defines a complimentary recess for receiving the radially
extending formation, the at least one formation or the at least one co-operating
formation extending in both the circumferential direction and the axial direction;
the actuation mechanism is arranged such that as the cam member is rotated
relative to the carrier member, the at least one formation and the at least one co
operating formation engage such that the at least one co-operating formation is
moved in the axial direction, thereby moving the carrier member in the axial
direction, and thereby moving the movable wall member in the axial direction so
as to vary the size of the inlet passageway;
wherein the cam member is disposed radially outwardly of the movable wall
member.
This is advantageous in that it provides a relatively compact variable geometry turbine
arrangement. In addition, the cam member, carrier member and movable wall member
can be formed as a self-contained cartridge that is relatively compact and easy to
install.
Furthermore, the above arrangement does not require axial push rods to move the
moveable wall member and so does not require the sealing arrangement necessary
where push rods are used, which is relatively expensive, wears easily and requires
water cooling. Therefore the above arrangement is relatively inexpensive, durable and
compact.
Optionally the cam member is annular. Optionally the cam member extends in the
circumferential direction about the turbine axis.
Optionally the movable wall member is annular. Optionally the movable wall member
extends in the circumferential direction about the turbine axis.
Optionally the turbine assembly further comprises a nozzle ring having a plurality of
circumferentially distributed inlet vanes and an annular shroud provided with a plurality
of slots for receiving the inlet vanes of the nozzle ring as the shroud is moved axially
relative to the nozzle ring.
The nozzle ring and/or the shroud may comprise the movable wall member.
The nozzle ring and shroud may be mounted on the same or different sides of the inlet
passageway. Where the shroud comprises the movable wall member, the nozzle ring
and shroud may be mounted on the same axial side of the inlet passageway.
Optionally the carrier member is annular.
Optionally the cam member and the carrier member axially overlap for at least one
axial position of the movable wall member.
Optionally the at least one formation and the at least one co-operating formation extend
in both the circumferential direction and the axial direction. Preferably only the at least
one formation or the at least one co-operating formation extends in both the
circumferential direction and the axial direction.
Any of the first to the third aspects of the invention may comprise any of the following
features, in any combination.
The movable wall member may be part of the shroud. In this case, the carrier member
may be coupled to the shroud such that as the carrier member moves axially, the
shroud moves axially. The carrier member may be part of the shroud such that as the
carrier member moves axially, the shroud moves axially.
In this case, the shroud and nozzle ring may be mounted on the same axial side of the
inlet passageway. The nozzle ring may be substantially fixed in the axial direction.
The movable wall member may be part of the nozzle ring. In this case, the carrier
member may be coupled to the nozzle ring such that as the carrier member moves
axially, the nozzle ring moves axially. The carrier member may be part of the nozzle
ring such that as the carrier member moves axially, the nozzle ring moves axially.
In this case, the shroud and nozzle ring may be mounted on opposite axial sides of the
inlet passageway. The shroud may be substantially fixed in the axial direction.
Optionally the nozzle ring comprises an annular radially extending wall, the plurality of
circumferentially distributed inlet vanes extend axially inboard from an inboard surface
of the radially extending wall and the annular shroud comprises an annular radially
extending wall provided with said plurality of slots, wherein the radially extending wall
of the nozzle ring is mounted axially outboard of the radial wall of the shroud.
Optionally the variable geometry turbine assembly comprises a bearing housing
arranged to house at least one bearing that rotatably supports a shaft on which the
turbine wheel is mounted and the shroud and the nozzle ring are mounted on the same
axial side of the inlet passageway as the bearing housing.
Alternatively, the shroud and nozzle ring may be mounted on an opposite axial side of
the inlet passageway to the bearing housing. In this regard, the shroud and nozzle ring
may be mounted on the same axial side of the inlet passageway as the turbine
housing.
Optionally the nozzle ring is substantially fixed in the axial direction. In this regard, the
inlet vanes of the nozzle ring are disposed in the inlet passageway. The inlet vanes
may extend substantially across the width of the inlet passageway.
Optionally the nozzle ring is also movable in the axial direction, so as to vary the axial
extent of the inlet vanes in the inlet passageway.
Optionally the one of the at least one formation and the at least one co-operating
formation that extends in both the circumferential direction and the axial direction is
said complimentary recess and the other is said radially extending formation.
Optionally the at least one co-operating formation is said radially extending formation
and the at least one formation defines said complimentary recess to receive the radially
extending formation.
Optionally the at least one formation is said complimentary recess and extends in both
the circumferential direction and the axial direction and the at least one co-operating
formation is said radially extending formation.
Optionally the co-operating formation is part of the carrier member.
Alternatively, the at least one co-operating formation may be a separate entity to the
carrier member. In this case, optionally the at least one co-operating formation is a
radially extending coupling element. Optionally the carrier member has an annular wall
provided with at least one radially extending bore and the at least one radially
extending coupling element is received in the at least one radially extending bore such
that as the at least one coupling element is moved in the axial direction, the carrier
member is moved in the axial direction.
The at least one coupling element may be elongate, having a longitudinal axis that is
substantially parallel to the radial direction. The longitudinal axis of the at least one
coupling element may be substantially straight.
The at least one coupling element may be a pin. The at least one coupling element
may be substantially cylindrical.
Optionally the one of the at least one formation and the at least one co-operating
formation that extends in both the circumferential direction and the axial direction
defines at least part of a helix. Optionally the one of the at least one formation and the
at least one co-operating formation that extends in both the circumferential direction
and the axial direction is substantially helical.
Optionally the complimentary recess is a radially extending slot.
The carrier member may be substantially rotationally fixed about the turbine axis.
Optionally the at least one formation is said complimentary recess and extends in both
the circumferential direction and the axial direction and the at least one co-operating
formation is said radially extending formation and a wall member is provided with at
least one axially extending slot, the at least one co-operating formation being received
in the at least one axially extending slot and wherein the actuation mechanism is
arranged such that as the cam member is rotated relative to the carrier member, the at
least one formation and the at least one co-operating formation engage such that the at
least one co-operating formation is moved in the axial direction, along the at least one
axially extending slot in said wall member, thereby moving the carrier member in the
axial direction and thereby moving the movable wall member in the axial direction, so
as to vary the width of the inlet passageway.
Optionally, where the shroud comprises the movable wall member, the nozzle ring and
shroud are arranged such that as the shroud is moved axially, the engagement of the
vanes with the slots guides the shroud in the axial direction. Optionally the engagement
of the vanes with the slots limits the rotation of the shroud about the turbine axis, as the
shroud is moved in the axial direction. Optionally the engagement of the vanes with
the slots substantially prevents the shroud from rotating about the turbine axis, as the
shroud is moved in the axial direction. Optionally the nozzle ring is substantially
rotationally fixed about the turbine axis.
Optionally the nozzle ring and shroud are arranged such that as the shroud is moved
axially, the engagement of the at least one formation and the at least one co-operating
formation rotates the shroud such that, for each slot in the shroud, at least a portion of
an inner surface that defines the slot abuts against an opposed surface of a vane of the
nozzle ring that is received within the slot. This advantageously reduces leakage of
exhaust gas from the inlet passageway, through the slots in the shroud.
Optionally the nozzle ring and shroud are arranged such that as the cam member is
rotated in a first rotational direction, for each slot in the shroud, a first portion of an
inner surface that defines the slot abuts against an opposed surface of a vane of the
nozzle ring that is received within the slot and as the cam member is rotated in a
second rotational direction, for each slot in the shroud, a second portion of an inner
surface that defines the slot abuts against an opposed surface of a vane of the nozzle
ring that is received within the slot. It will be appreciated that the first and second
rotational directions are opposite to each other.
Optionally the variable geometry turbine assembly comprises a bearing housing
arranged to house at least one bearing that rotatably supports a shaft on which the
turbine wheel is mounted and the shroud and the actuation mechanism is mounted on
the same axial side of the inlet passageway as the bearing housing.
Optionally where the at least one formation defines said complimentary recess, the
recess is provided in a circumferential section of the cam ring that is of greater radial
thickness than the remainder of the cam ring.
Optionally where the at least one formation defines said complimentary recess and the
at least one co-operating formation is said radially extending formation and is part of
the carrier member, the complimentary recess has an open end for receipt of the c o
operating formation.
Optionally the cam member is provided with a plurality of said formations, distributed in
the circumferential direction.
Optionally the carrier member is coupled to a plurality of said co-operating formations,
distributed in the circumferential direction.
Optionally where the shroud comprises the movable wall member, the shroud also
comprises the carrier member. Alternatively, the carrier member may be a separate
entity to the shroud.
The nozzle ring may comprise the movable wall member. In this case, the nozzle ring
may comprise the carrier member.
Optionally at least one seal is provided between the movable wall member and an
adjacent surface such so as to substantially prevent exhaust gas from the inlet
passageway passing outboard of the seal.
The seal may be mounted to the movable wall member, to move axially with the
movable wall member. Alternatively, the seal may be axially fixed relative to said
adjacent surface.
Where the shroud comprises said movable wall member, the shroud may be slidably
mounted in the nozzle ring, with the at least one seal provided between a surface of the
shroud and an opposed surface of the nozzle ring. The at least one seal may be
provided between an annular axially extending flange of the seal, that extends inboard
from a radial wall of the shroud that forms the movable wall member and an opposed
surface of the nozzle ring.
Alternatively, or additionally, optionally said annular axially extending flange forms a
radially inner flange, wherein the shroud comprises a radially outer annular axially
extending flange that extends inboard from a radial wall of the shroud, wherein the at
least one seal is provided between the radially outer flange and an opposed surface of
the nozzle ring.
The nozzle ring may comprise a heat shield integrally formed with the nozzle ring and
disposed between the turbine wheel and a component of the variable geometry turbine
assembly, arranged to protect said component from the hot gases in the turbine.
The heat shield may be formed by a radially inner section of the nozzle ring, disposed
between the turbine wheel and said component of the variable geometry turbine
assembly.
The heat shield section may be made of a heat resistant material, including stainless
steel (e.g. 304 or pl33), Inconel or any suitable heat resistant material.
The variable geometry turbine assembly may comprise a biasing member arranged to
bias the tips of the guide vanes into contact with the facing wall. The biasing member
may be a resiliently deformable annular member.
Optionally the heat shield is not attached to the nozzle ring and the biasing member is
arranged to bias the tips of the guide vanes into contact with the facing wall without
exerting an inboard axial force on the heat shield. In this regard, the heat shield may
comprise an annular lip that is disposed outboard of the biasing member.
Preferably the actuation mechanism is arranged such that as the cam member is
rotated relative to the carrier member in first and second rotational directions, the
carrier member, and so the movable wall member, is moved in the first and second
axial directions respectively.
Preferably the second axial direction is opposite to the first axial direction.
Preferably the second rotational direction is opposite to the first rotational direction.
The variable geometry turbine assembly may further comprise a support member
comprising an annular wall, wherein the carrier member is axially slidably mounted on
a radially outer surface of the annular wall of the support member. The carrier member
may be mounted directly on the support member.
Preferred embodiments of the variable geometry turbine assembly of the first to the
third aspects of the invention are the first to the fourth embodiments of the invention
shown in Figures 1 to 95. The variable geometry turbine assembly of the first to the
third aspects of the invention may have any of the features of the first to the fourth
embodiments.
A wall member of the variably geometry turbine assembly may be provided with a
formation that is arranged to engage with a complimentary formation on the nozzle
ring, the carrier member, the cam member and/or the support member such that when
the formations are engaged, the nozzle ring, carrier member, cam member and/or the
support member is in a specific rotational orientation about the turbine axis.
The formation and complimentary formation may be a recess or protrusion, or vice
versa. The wall member may be a wall member of a bearing housing.
The support member may be provided with the complimentary formation, such that
when the formations are engaged, the support member is in a specific rotational
orientation about the turbine axis, relative to the bearing housing. The support member
may be provide with a second formation for engagement with a second complimentary
formation on the nozzle ring or shroud such that when the second formation and
second complimentary formation are engaged the nozzle ring or shroud, respectively,
is in a specific rotational orientation about the turbine axis, relative to the support
member.
The second formation and second complimentary formation may be a recess or
protrusion, or vice versa.
According to a fourth aspect of the invention there is provided a variable geometry
turbine assembly comprising:
a turbine wheel mounted within a turbine housing for rotation about a turbine
axis;
an annular inlet passageway extending radially inwards towards the turbine
wheel;
the annular inlet passageway being defined between a surface of a movable wall
member and a facing wall of the variable geometry turbine assembly;
the movable wall member being movable in the axial direction so as to vary the
size of the annular inlet passageway,
and an actuation mechanism arranged to move the movable wall member axially
relative to the facing wall;
the actuation mechanism comprising:
a carrier member, the carrier member being movable in the axial direction and
coupled to the movable wall member such that as the carrier member is moved in
the axial direction, the moveable wall member is moved in the axial direction, the
carrier member having an annular wall provided with at least one radially
extending bore;
at least one radially extending coupling element received in the at least one
radially extending bore in the annular wall of the carrier member such that as the
at least one coupling element is moved in the axial direction, the carrier member
is moved in the axial direction;
a cam member mounted for rotation about the turbine axis, the cam member
having an annular wall provided with at least one slot defined by at least one
surface of the annular wall, the at least one slot extending in both the
circumferential direction and the axial direction;
the at least one coupling element also being received in the at least one slot in
the cam member;
wherein a wall member is provided with at least one axially extending slot, the at
least one coupling element also being received in at least one axially extending
slot;
and wherein the actuation mechanism is arranged such that as the cam member
is rotated about the turbine axis, the at least one slot in the annular wall of the
cam member is moved relative to the at least one coupling element, with the at
least one surface of the cam member that defines the at least one slot acting on
the at least one coupling element to move the at least one coupling element in a
the axial direction, along the at least one axially extending slot in said wall
member, thereby moving the carrier member in the axial direction and thereby
moving the movable wall member in the axial direction, so as to vary the width of
the inlet passageway.
This is advantageous in that it provides a relatively compact variable geometry turbine
arrangement. In addition, the cam member, carrier member and movable wall member
can be formed as a self-contained cartridge that is relatively compact and easy to
install.
Furthermore, the above arrangement does not require axial push rods to move the
moveable wall member and so does not require the sealing arrangement necessary
where push rods are used, which is relatively expensive, wears easily and requires
water cooling. Therefore the above arrangement is relatively inexpensive, durable and
compact.
The facing wall may be a facing wall of the housing.
Preferably the actuation mechanism is arranged such that as the cam member is
rotated about the turbine axis in first and second rotational directions, the at least one
slot in the cam member is moved relative to the at least one coupling element, with the
at least one surface of the cam member that defines the at least one slot acting on the
at least one coupling element to move the at least one coupling element in first and
second axial directions respectively, along the at least one axially extending slot in said
wall member, thereby moving the carrier member in the first and second axial
directions respectively and thereby moving the movable wall member in the first and
second axial directions respectively.
Preferably the second axial direction is opposite to the first axial direction.
Preferably the second rotational direction is opposite to the first rotational direction.
The carrier member may be axially fixed relative to the movable wall member. The
carrier member may be rotationally fixed relative to the movable wall member. The
carrier member may be fixed directly to the movable wall member.
The carrier member may be arranged such that it is rotationally fixed about the turbine
axis. In this regard, preferably as the carrier member moves axially, it does not rotate
about the turbine axis.
The at least one radially extending bore in the annular wall of the carrier member may
extend along a longitudinal axis that is substantially parallel to the radial direction. The
longitudinal axis of the at least one radially extending bore may be substantially
straight.
The at least one coupling element may be axially fixed relative to the carrier member.
The at least one radially extending bore in the annular wall of the carrier member and
the at least one coupling element may be arranged such that as the at least one
coupling element is moved in the first and second axial directions, the carrier member
is moved in the first and second axial directions respectively.
The at least one radially extending bore may have an axial extent that is substantially
the same as, or slightly greater than, the axial extent of the at least one coupling
element such that as the at least one coupling element is moved in the first and second
axial directions, the carrier member is moved in the first and second axial directions
respectively.
The annular wall of the carrier member may have a radially inner and/or outer surface
that extends substantially parallel to the axial direction.
The annular wall of the carrier member and the annular wall of the cam member may
be substantially concentric. The annular wall of the carrier member and the annular
wall of the cam member may be substantially concentric with the turbine axis.
The cam member may be rotationally mounted on, and supported for rotation by, the
carrier member. In this case, the carrier member may be mounted radially inwardly of
the cam member. A radially inner surface of the cam member may bear against a
radially outer surface of the annular wall of the carrier member, as the cam member
rotates and/or as the carrier member moves axially. The at least one radially extending
bore may extend radially inwardly from a first end, provided in a radially outer surface
of the carrier member, to a second end.
Alternatively, the cam member may be mounted radially inwardly of the carrier
member. In this case, the at least one radially extending bore may extend radially
outwardly from a first end, provided in a radially inner surface of the carrier member, to
a second end.
In each case, the second end of the bore may be closed, such that the bore is a blind
bore.
The at least one coupling element may be elongate, having a longitudinal axis that is
substantially parallel to the radial direction. The longitudinal axis of the at least one
coupling element may be substantially straight.
The at least one coupling element may be a pin. The at least one coupling element
may be substantially cylindrical.
The cam member may be rotationally mounted such that it is substantially fixed in the
axial direction as it rotates. The cam member may be housed between first and
second opposed radially extending surfaces that substantially fix the cam member in
the axial direction as it rotates. The first and second radially extending surfaces may
be a surface of a wall of the turbine housing and a surface of a wall of a bearing
housing of the variably geometry turbine assembly respectively.
The annular wall of the cam member may have a radially inner and/or outer surface
that extends substantially parallel to the axial direction.
The at least one slot in the annular wall of the cam member may extend substantially
through the radial thickness of the annular wall.
The at least one slot in the annular wall of the cam member may be generally elongate,
extending along a longitudinal axis.
The longitudinal axis of the at least one slot may be inclined at a substantially constant
angle relative to the radial plane. In this respect, the radial plane is a plane that is
substantially perpendicular to the turbine axis.
The longitudinal axis of the at least one slot may be inclined at an angle relative to the
radial plane that varies along its length. This is advantageous in that it allows for a
desired axial movement of the movable wall member for a certain rotational movement
of the cam member.
In this case, the angle of the longitudinal axis relative to the radial plane may decrease
from a first end of the slot to a second end of the slot such that the at least one slot
forms a concave curve. The angle of the longitudinal axis relative to the radial plane
may increase and then decrease from a first end of the slot to a second end of the slot
such that the at least one slot forms a curved wave shape.
A surface of the wall member that defines the at least one axially extending slot in the
wall member may be arranged such that as the at least one surface of the annular wall
member of the cam member that defines the at least one slot acts on the at least one
coupling element to move the at least one coupling element in the axial direction, along
the at least one axially extending slot in the wall member, the surface of the wall
member that defines the at least one axially extending slot reacts the force applied to
the at least one coupling element by the at least one surface of the annular wall
member of the cam member that defines the at least one slot such that the at least one
coupling element is moved in the axial direction along the axially extending slot.
The at least one axially extending slot may extend along a longitudinal axis that does
not extend in the circumferential direction (i.e. the circumferential direction relative to
the turbine axis). The at least one axially extending slot may be substantially straight in
the axial direction.
Optionally the at least one axially extending slot has a width in the circumferential
direction that is substantially equal to, or slightly greater than, the width of the at least
one coupling element in the circumferential direction such that the at least one coupling
element is prevented from moving in the circumferential direction as it moves along the
at least one axially extending slot.
The variable geometry turbine assembly may comprise an annular wall member,
wherein the cam member is mounted radially inwardly of the annular wall member such
that a radially outer surface of the annular wall of the cam member is opposed and
adjacent to a radially inner surface of the annular wall member. The radially outer
surface of the annular wall of the cam member may bear against the radially inner
surface of the annular wall member as the cam member rotates.
The wall member that is provided with said at least one axially extending slot may be a
wall member of a bearing housing of the variable geometry turbine assembly.
Alternatively, said housing may be any other housing of the variable geometry turbine
assembly.
The wall member that is provided with said at least one axially extending slot may be
said annular wall member.
The at least one slot provided in the annular wall of the cam member, the at least one
radially extending bore provided in the annular wall of the carrier member, the at least
one axial slot provided in said wall member and the at least one coupling element may
be a plurality of said slots, radially extending bores, axial slots and coupling elements
respectively, wherein each coupling element is received in a respective said radially
extending bore in the carrier member, in a respective said slot in the annular wall of the
cam member and in a respective said axially extending slot in said wall member.
The plurality of radially extending bores in the annular wall of the carrier member may
be distributed in the circumferential direction about the annular wall of the carrier
member.
The plurality of slots in the annular wall of the cam member may be distributed in the
circumferential direction about the annular wall of the cam member.
The plurality of axially extending slots in the wall member may be distributed in the
circumferential direction about said wall member.
The variable geometry turbine assembly may further comprise a support member
comprising an annular wall, wherein the carrier member is axially slidably mounted on
a radially outer surface of the annular wall of the support member. The carrier member
may be mounted directly on the support member.
The radially inner and/or radially outer surface of the annular wall of the support
member may extend substantially parallel to the axial direction.
The support member may be made of stainless steel.
The support member and/or the carrier member may be provided with a coating that
acts to reduce friction between the carrier member and the support member.
Additionally, or alternatively, the support member may be provided with a coating of a
material that is resistant to wear. The coating may be CM1 1. The support member
and/or carrier member may be subjected to a boronised surface treatment.
The support member may be substantially fixed in the axial direction. The support
member may be mounted on and fixed to a housing of the variable geometry turbine
assembly. The housing may be a bearing housing.
At least one sealing element may be provided between the support member and the
housing so as to provide a seal between the support member and the housing. The
housing may be a bearing housing.
The at least one sealing element may be an annular seal. The at least one sealing
element may extend substantially around the inner circumference of the support
member. The at least one sealing element may be fixedly attached to the support
member or the housing. The at least one sealing element may be mounted in a
circumferential groove defined in the housing or in the support member.
At least one sealing element may be provided between the carrier member and the
support member so as to provide a seal between the carrier member and the support
member as the carrier member moves axially relative to the support member. The at
least one sealing element may be an annular seal. The at least one sealing element
may extend substantially around the inner circumference of the carrier member.
The at least one sealing element may be fixedly attached to the carrier member. The
at least one sealing element may be mounted in a circumferential groove defined in the
carrier member. Alternatively, the at least one sealing element may be fixedly attached
to the support member. In this case, the at least one sealing element may be mounted
in a circumferential groove defined in the support member.
Instead of being axially slidably mounted a support member, the carrier member may
be axially slidably mounted on a housing of the variable geometry turbine assembly,
such as a bearing housing.
The variable geometry turbine assembly may comprise a nozzle ring. The nozzle ring
may be provided with a plurality of guide vanes distributed circumferentially about the
nozzle ring that extend into the annular inlet passageway. Each guide vane may
extend from a root to a tip.
The nozzle ring may be axially fixed relative to the facing wall of the housing. The
nozzle ring may be axially and/or rotationally fixed to the support member.
The variable geometry turbine assembly may comprise an annular shroud. The
annular shroud may comprise an annular wall provided with a plurality of slots, wherein
each slot is arranged to receive a respective guide vane of the nozzle ring as the
shroud is moved axially relative to the nozzle ring.
The moveable wall member may be the annular wall of a shroud.
The variable geometry turbine assembly may comprise a biasing member arranged to
bias the tips of the guide vanes into contact with the facing wall of the housing. The
biasing member may be a resiliently deformable annular member.
Alternatively, the movable wall member may be the nozzle ring. In this case the facing
wall of the housing may be the annular wall of the shroud.
The actuation mechanism may be provided on the same axial side of the annular inlet
passageway as the movable wall member. Alternatively, the actuation mechanism may
be provided on the opposite axial side of the annular inlet passageway to the movable
wall member.
The actuation mechanism may be mounted on the same side of the annular inlet
passageway as a bearing housing of the variable geometry turbine assembly.
Alternatively, the actuation mechanism may be mounted on the same side of the
annular inlet passageway as the turbine housing.
The actuation mechanism may be mounted between a bearing housing and a turbine
housing of the variable geometry turbine assembly.
The facing wall of the housing may be a wall of the turbine housing. Alternatively, the
facing wall of the may be a wall of any other housing of the variably geometry turbine
assembly, including a wall of a bearing housing.
The variable geometry turbine assembly may further comprise an actuator coupled to
the cam member so as to rotate the cam member about the turbine axis. The actuator
may be coupled to the cam member by rotatable arm, wherein the cam member is
provided with a formation that engages with the arm such that rotation of the arm by
the actuator rotates the cam member about the turbine axis. The formation may be a
radially extending protrusion that defines a cavity for receipt of the arm.
The actuator may be any suitable actuator, including an electrical, pneumatic or
hydraulic actuator.
The carrier member may be provided with at least one recessed portion so as to
provide clearance for the rotation of the arm. The recess may be in the radial and/or
axial directions. The carrier member may be provided with a plurality of said recessed
portions distributed in the circumferential direction.
Where the nozzle ring is axially fixed, the nozzle ring may comprise a heat shield
integrally formed with the nozzle ring and disposed between the turbine wheel and a
component of the variable geometry turbine assembly, arranged to protect said
component from the hot gases in the turbine.
The heat shield may be formed by a radially inner section of the nozzle ring, disposed
between the turbine wheel and said component of the variable geometry turbine
assembly.
The heat shield section may be made of a heat resistant material, including stainless
steel (e.g. 304 or pl33), Inconel or any suitable heat resistant material.
The carrier member, movable wall member, cam member and the at least one coupling
element may form a cartridge assembly. Where the variable geometry turbine
assembly comprises said support member, the support member and optionally the
nozzle ring may also form part of the cartridge assembly.
A wall member of the variably geometry turbine assembly may be provided with a
formation that is arranged to engage with a complimentary formation on nozzle ring,
the carrier member, the cam member and/or the support member such that when the
formations are engaged, the nozzle ring, carrier member, cam member and/or the
support member is in a specific rotational orientation about the turbine axis.
The formation and complimentary formation may be a recess and protrusion, or vice
versa. The wall member may be a wall member of a bearing housing.
Any of the features of the fourth aspect of the invention may be combined with any of
the features of any of the preceding aspects of the invention, in any combination.
Similarly, any of the features of the preceding aspects of the invention may be
combined with any of the features of the fourth aspect of the invention, in any
combination.
A preferred embodiment of the variable geometry turbine assembly of the fourth aspect
of the invention is the first embodiment of the invention shown in Figures 1 to 24c. The
variable geometry turbine assembly of the fourth aspect of the invention may have any
of the features of the first embodiment.
An actuator may be coupled to the cam member so as to rotate the cam member. The
actuator may be any suitable actuator, including a pneumatic, hydraulic or electric
actuator.
According to a fifth aspect of the invention there is provided an actuation mechanism
assembly comprising an actuation mechanism for moving a movable wall member, a
surface of which defines, with a facing wall, an annular inlet passageway of a turbine,
so as to vary the width of the annular inlet passageway, the actuation mechanism
comprising:
a carrier member, the carrier member being movable in an axial direction and
coupled to the movable wall member such that as the carrier member is moved in
the axial direction, the moveable wall member is moved in the axial direction
a cam member provided with at least one formation;
the carrier member being coupled to at least one co-operating formation such
that as the at least one co-operating formation is moved in the axial direction, the
carrier member is moved in the axial direction, wherein one of the at least one
formation and the at least one co-operating formation is a radially extending
formation and the other defines a complimentary recess for receiving the radially
extending formation, the at least one formation or the at least one co-operating
formation extending in both the circumferential direction and the axial direction;
the actuation mechanism is arranged such that as the cam member is rotated
relative to the carrier member, the at least one formation and the at least one co
operating formation engage such that the at least one co-operating formation is
moved in the axial direction, thereby moving the carrier member in the axial
direction, and thereby moving the movable wall member in the axial direction so
as to vary the size of the inlet passageway;
the actuation member assembly further comprising a nozzle ring having a
plurality of circumferentially distributed inlet vanes and an annular shroud
provided with a plurality of slots for receiving the inlet vanes of the nozzle ring as
the shroud is moved axially relative to the nozzle ring;
wherein the shroud comprises the movable wall member;
and the nozzle ring and shroud are mountable on the same axial side of the inlet
passageway.
According to a sixth aspect of the invention there is provided an actuation mechanism
for moving a movable wall member, a surface of which defines, with a facing wall, an
annular inlet passageway of a turbine, so as to vary the width of the annular inlet
passageway, the actuation mechanism comprising:
an annular carrier member, the carrier member being movable in an axial
direction and for coupling to the movable wall member such that as the carrier
member is moved in the axial direction, the moveable wall member is moved in
the axial direction
a cam member mounted for rotation;
the cam member is provided with at least one formation;
the carrier member being coupled to at least one co-operating formation such
that as the at least one co-operating formation is moved in the axial direction, the
carrier member is moved in the axial direction, wherein one of the at least one
formation and the at least one co-operating formation is a radially extending
formation and the other defines a complimentary recess to receive the radially
extending formation, the at least one formation extending in both the
circumferential direction and the axial direction;
the actuation mechanism is arranged such that as the cam member is rotated,
the at least one formation and the at least one co-operating formation engage
such that the at least one co-operating formation is moved in the axial direction,
thereby moving the carrier member in the axial direction, and thereby moving the
movable wall member in the axial direction so as to vary the size of the inlet
passageway;
wherein the cam member and the carrier member axially overlap for at least one
axial position of the movable wall member.
According to a seventh aspect of the invention there is provided there is provided an
actuation mechanism assembly comprising an actuation mechanism and a movable
wall member, wherein the actuation mechanism is for moving the movable wall
member, a surface of which defines, with a facing wall, an annular inlet passageway of
a turbine, so as to vary the width of the annular inlet passageway, the actuation
mechanism comprising:
a carrier member, the carrier member being movable in an axial direction and
coupled to the movable wall member such that as the carrier member is moved in
the axial direction, the moveable wall member is moved in the axial direction
a cam member provided with at least one formation;
the carrier member being coupled to at least one co-operating formation such
that as the at least one co-operating formation is moved in the axial direction, the
carrier member is moved in the axial direction, wherein one of the at least one
formation and the at least one co-operating formation is a radially extending
formation and the other defines a complimentary recess for receiving the radially
extending formation, the at least one formation or the at least one co-operating
formation extending in both the circumferential direction and the axial direction;
the actuation mechanism is arranged such that as the cam member is rotated
relative to the carrier member, the at least one formation and the at least one co
operating formation engage such that the at least one co-operating formation is
moved in the axial direction, thereby moving the carrier member in the axial
direction, and thereby moving the movable wall member in the axial direction so
as to vary the size of the inlet passageway;
wherein the cam member is disposed radially outwardly of the movable wall
member.
According to an eighth aspect of the invention there is provided an actuation
mechanism for moving a movable wall member, a surface of which defines, with a
facing wall of a housing, an annular inlet passageway of a turbine, so as to vary the
width of the annular inlet passageway, the actuation mechanism comprising:
a carrier member for coupling to a movable wall member, a surface of which
defines, with a facing wall of a housing, an annular inlet passageway of a
turbine, such that as the carrier member is moved in the direction of a
longitudinal axis of the carrier member, the moveable wall member is moved in
the axial direction, the carrier member having an annular wall provided with at
least one radially extending bore;
at least one radially extending coupling element being received in the at least
one radially extending bore in the annular wall of the carrier member such that
as the at least one coupling element is moved in the axial direction, the carrier
member is moved in the axial direction;
a cam member mounted for rotation about said axis, the cam member having
an annular wall provided with at least one slot defined by at least one surface of
the annular wall, the at least one slot extending in both the circumferential
direction and the axial direction;
the at least one coupling element also being received in the at least one slot in
the cam member;
the at least one coupling element being for receipt in at least one axially
extending slot in a wall member such that as the cam member is rotated about
said axis, the at least one slot in the annular wall of the cam member is moved
relative to the at least one coupling element, with the at least one surface of the
cam member that defines the at least one slot acting on the at least one
coupling element to move the at least one coupling element in a the axial
direction, along the at least one axially extending slot in said wall member,
thereby moving the carrier member in the axial direction and thereby moving
the movable wall member in the axial direction, so as to vary the width of the
inlet passageway.
According to a ninth aspect of the invention there is provided a turbomachine
comprising a variable geometry turbine assembly according to any of the first to the
fourth aspects of the invention.
The turbomachine may comprise a bearing housing arranged to house at least one
bearing that rotatably supports a shaft on which the turbine wheel is mounted and
wherein the wall member provided with the at least one axially extending slot is a wall
member of the bearing housing.
The turbomachine may be a turbocharger, wherein the turbine wheel is mounted on a
shaft, the turbocharger comprising a compressor having an impeller wheel rotatably
mounted within a compressor housing and coupled to the shaft such that rotation of the
turbine wheel rotates the compressor wheel thereby drawing air in through an inlet of
the compressor, compressing the air and passing it to an outlet of the compressor.
Any features of any of the above aspects of the invention may be combined with any
features of any other aspect of the invention in any combination. In this regard, the
actuation mechanism of any of the fifth to the eighth aspects of the invention may have
any feature of the variable geometry turbine assembly of any preceding aspect of the
invention.
Specific embodiments of the present invention will now be described, by way of
example only, with reference to the accompanying drawings, in which:
Figure 1 is an axial cross section through a variable geometry turbocharger according
to a first embodiment of the present invention;
Figure 2 is an exploded perspective view of part of a variable geometry turbine and of a
bearing housing of the variable geometry turbocharger shown in figure 1;
Figure 3 is a view corresponding to that of Figure 2 , but with a circumferential section
cut away for illustrative purposes;
Figure 4 is an axial cross-section through a cam member, carrier member, support
member, shroud and nozzle ring of the variable geometry turbine shown in figures 1 to
3 ;
Figure 5 is a rear perspective view of a cam member of the variable geometry turbine
shown in figures 1 to 3 ;
Figure 6 is a front perspective view of a nozzle ring of the variable geometry turbine
shown in figures 1 to 3 ;
Figure 7 is an axial cross-sectional view of the nozzle ring shown in figure 6 ;
Figure 8 is a rear perspective view of the nozzle ring shown in figures 6 and 7 ;
Figure 9 is a front perspective view of a support member of the variable geometry
turbine shown in figures 1 to 3 ;
Figure 10 is an axial cross-sectional view of the support member shown in figure 9 ;
Figure 11 is a front perspective view of a shroud of the variable geometry turbine
shown in figures 1 to 3 ;
Figure 1 is an axial cross-sectional view of the shroud shown in figure 11;
Figure 13 is a rear perspective view of the shroud shown in figures 11 and 12;
Figure 14 is a front perspective view of a carrier member of the variable geometry
turbine shown in figures 1 to 3 ;
Figure 15 is an axial cross-sectional view of the carrier member shown in figure 14;
Figure 16 is a rear perspective view of the carrier member shown in figures 14 and 15;
Figure 17 is a rear perspective view of a bearing housing of the turbocharger shown in
figures 1 to 3 ;
Figure 18 is an axial cross-sectional view of the bearing housing shown in figure 17;
Figure 19 is a front perspective view of the bearing housing shown in figures 17 and
18;
Figure 20 is an enlarged perspective view of the region labelled 'A' in Figure 19;
Figure 2 1 is a cut away perspective view of a turbine housing of the turbocharger
shown in figures 1 to 3 ;
Figure 22 is a perspective view of a rotatable arm assembly of the turbocharger shown
in figures 1 to 3 ;
Figure 23 is a cut away perspective view of the rotatable arm assembly shown in figure
22,
Figure 24a is a side elevational view of the cam member shown in Figure 5 ;
Figures 24b and 24c are views corresponding to that of Figure 24a but where the slots
in the annular wall of the cam member are of a different shape (where the shape of the
slots is shown as a thicker darker line overlying the slot of Figure 24a);
Figure 25 is an axial cross section through a variable geometry turbocharger according
to a second embodiment of the present invention;
Figure 26 is an exploded perspective view of part of a variable geometry turbine and of
a bearing housing of the variable geometry turbocharger shown in figure 25;
Figure 27 is a view corresponding to that of Figure 26, but with a circumferential
section cut away for illustrative purposes;
Figure 28 is an axial cross-section through a cam member, carrier member, support
member, shroud and nozzle ring of the variable geometry turbine shown in figures 25
to 27;
Figure 29 is a rear perspective view of a cam member of the variable geometry turbine
shown in figures 25 to 27;
Figure 30 is a front perspective view of a nozzle ring of the variable geometry turbine
shown in figures 25 to 27;
Figure 3 1 is an axial cross-sectional view of the nozzle ring shown in figure 30;
Figure 32 is a rear perspective view of the nozzle ring shown in figures 30 and 3 1 ;
Figure 33 is a front perspective view of a support member of the variable geometry
turbine shown in figures 25 to 27;
Figure 34 is an axial cross-sectional view of the support member shown in figure 33;
Figure 35 is a front perspective view of a shroud of the variable geometry turbine
shown in figures 25 to 27;
Figure 36 is an axial cross-sectional view of the shroud shown in figure 35;
Figure 37 is a rear perspective view of the shroud shown in figures 35 and 36;
Figure 38 is a front perspective view of a carrier member of the variable geometry
turbine shown in figures 25 to 27;
Figure 39 is an axial cross-sectional view of the carrier member shown in figure 38;
Figure 40 is a rear perspective view of a bearing housing of the turbocharger shown in
figures 25 to 27;
Figure 4 1 is an axial cross-sectional view of the bearing housing shown in figure 40;
Figure 42 is a front perspective view of the bearing housing shown in figures 40 and
4 1 ;
Figure 43 is an enlarged perspective view of the region labelled 'A' in Figure 42;
Figure 44 is a cut away perspective view of a turbine housing of the turbocharger
shown in figures 25 to 27;
Figure 45 is a perspective view of a rotatable arm assembly of the turbocharger shown
in figures 25 to 27;
Figure 46 is a cut away perspective view of the rotatable arm assembly shown in figure
45;
Figure 47 is an axial cross section through a variable geometry turbocharger according
to a third embodiment of the present invention;
Figure 48 is an exploded perspective view of part of a variable geometry turbine and of
a bearing housing of the variable geometry turbocharger shown in figure 47;
Figure 49 is a view corresponding to that of Figure 48, but with a circumferential
section cut away for illustrative purposes;
Figure 50 is an axial cross-section through a carrier member, support member, shroud
and nozzle ring of the variable geometry turbine shown in figures 47 to 49;
Figure 5 1 is a rear perspective view of a cam member of the variable geometry turbine
shown in figures 47 to 49;
Figure 52 is a front perspective view of a nozzle ring of the variable geometry turbine
shown in figures 47 to 49;
Figure 53 is an axial cross-sectional view of the nozzle ring shown in figure 52;
Figure 54 is a rear perspective view of the nozzle ring shown in figures 52 and 53;
Figure 55 is a front perspective view of a support member of the variable geometry
turbine shown in figures 47 to 49;
Figure 56 is an axial cross-sectional view of the support member shown in figure 55;
Figure 57 is a rear perspective view of the support member shown in figures 55 and 56;
Figure 58 is an exploded perspective view, with a circumferential section cut away for
illustrative purposes, of a section of a bearing housing and the support member of the
variable geometry turbine shown in figures 47 to 49, showing how the support member
is slidably mounted to the bearing housing;
Figure 59 is a front perspective view of a shroud of the variable geometry turbine
shown in figures 47 to 49;
Figure 60 is an axial cross-sectional view of the shroud shown in figure 59;
Figure 6 1 is a rear perspective view of the shroud shown in figures 59 and 60;
Figure 62 is a front perspective view of a carrier member of the variable geometry
turbine shown in figures 47 to 49;
Figure 63 is an axial cross-sectional view of the carrier member shown in figure 62;
Figure 64 is a rear perspective view of a carrier member shown in Figures 62 and 63;
Figure 65 is a rear perspective view of a bearing housing of the turbocharger shown in
figures 47 to 49;
Figure 66 is an axial cross-sectional view of the bearing housing shown in figure 65;
Figure 67 is a front perspective view of the bearing housing shown in figures 65 and
66;
Figure 68 is a cut away perspective view of a turbine housing of the turbocharger
shown in figures 47 to 49;
Figure 69 is a perspective view of a rotatable arm assembly of the turbocharger shown
in figures 47 to 49;
Figure 70 is a cut away perspective view of the rotatable arm assembly shown in figure
69;
Figure 7 1 is an axial cross section through a variable geometry turbocharger according
to a fourth embodiment of the present invention;
Figure 72 is an exploded perspective view of part of a variable geometry turbine and of
a bearing housing of the variable geometry turbocharger shown in figure 7 1 ;
Figure 73 is a view corresponding to that of Figure 72, but with a circumferential
section cut away for illustrative purposes;
Figure 74 is an axial cross-section through a carrier member, support member, shroud
and nozzle ring of the variable geometry turbine shown in figures 7 1 to 73;
Figure 75 corresponds to Figure 74 but in exploded form;
Figure 76 is a rear perspective view of a cam member of the variable geometry turbine
shown in figures 7 1 to 73;
Figure 77 is a front perspective view of a nozzle ring of the variable geometry turbine
shown in figures 7 1 to 73;
Figure 78 is an axial cross-sectional view of the nozzle ring shown in figure 77;
Figure 79 is a rear perspective view of the nozzle ring shown in figures 77 and 78;
Figure 80 is a front perspective view of a support member of the variable geometry
turbine shown in figures 7 1 to 73;
Figure 8 1 is an axial cross-sectional view of the support member shown in figure 80;
Figure 82 is a front perspective view of a radial wall of shroud of the variable geometry
turbine shown in figures 7 1 to 73;
Figure 83 is a rear perspective view of the radial wall of the shroud shown in figure 82;
Figure 84 is an axial cross-sectional view of the radial wall of the shroud shown in
figures 82 and 83;
Figure 85 is a front perspective view of a radially inner axially extending annular flange
of the shroud of the variable geometry turbine shown in figures 7 1 to 73;
Figure 86 is an axial cross-sectional view of the radially inner axially extending annular
flange of the shroud shown in figure 85;
Figure 87 is a front perspective view of a radially outer axially extending annular flange
of the shroud of the turbocharger shown in Figures 7 1 to 73;
Figure 88 is an axial cross-sectional view of the radially outer axially extending annular
flange of the shroud shown in Figure 87;
Figure 89 is a rear perspective view of radially outer, axially extending annular flange of
the shroud shown in Figures 87 and 88;
Figure 90 is a rear perspective view of a bearing housing of the turbocharger shown in
figures 7 1 to 73;
Figure 9 1 is an axial cross-sectional view of the bearing housing shown in figure 90;
Figure 92 is a front perspective view of a bearing housing of the turbocharger shown in
figures 90 and 9 1 ;
Figure 93 is a cut away perspective view of a turbine housing of the turbocharger
shown in figures 7 1 to 73;
Figure 94 is a perspective view of a rotatable arm assembly of the turbocharger shown
in figures 7 1 to 73, and
Figure 95 is a cut away perspective view of the rotatable arm assembly shown in figure
94.
Referring to Figures 1 to 24 there is shown a variable geometry turbocharger 1
comprising a variable geometry turbine assembly according to a first embodiment of
the present invention. The variable geometry turbocharger 1 comprises a variable
geometry turbine 6 1 connected to a compressor 92 by a bearing assembly 93.
In more detail, the variable geometry turbine 9 1 comprises a turbine housing 2 that is
connected to a compressor housing 3 of the compressor 92 by a central bearing
housing 4 of the bearing assembly 93.
The turbocharger 1 has a turbocharger axis 5a. The turbocharger 1 is generally
symmetric about the turbocharger axis 5a. The variable geometry turbine 9 1 has a
turbine axis 105a, which is coincident with and substantially parallel to the turbocharger
axis 5a.
It will be appreciated that, unless otherwise stated, references to 'radially extending',
'radial', 'axially extending', 'axial, 'circumferentially extending' and 'circumferential' are
in relation to the turbocharger axis 5a (and therefore also the turbine axis 105a).
A turbocharger shaft 5 extends from the turbine housing 2 to the compressor housing 3
through the bearing housing 4 . A turbine wheel 6 is mounted on one end of the shaft 5
for rotation within the turbine housing 2 about the turbocharger axis 5a. The
compressor wheel 7 is mounted on the other end of the shaft 5 for rotation within the
compressor housing 3 . The shaft 5 rotates about the turbocharger axis 5a and is
supported for rotation by bearings 94 located in the bearing housing 4 .
The turbine housing 2 defines an inlet volute 8 to which gas from an internal
combustion engine (not shown) is delivered. The exhaust gas flows from the inlet
volute 8 to an axial outlet passageway 9 via an annular inlet passageway 10 and the
turbine wheel 6 .
References to 'inboard' and 'outboard' are in relation to the annular inlet passageway
10.
Gas flowing from the inlet volute 8 to the outlet passageway 9 passes over the turbine
wheel 6 and as a result torque is applied to the shaft 5 to drive the compressor wheel
7 . Rotation of the compressor wheel 7 within the compressor housing 3 pressurises
ambient air in an axial inlet 101 defined by the compressor housing 3 and delivers the
pressurised air to an annular outlet volute 102 from which it is fed to an internal
combustion engine (not shown). Details of the compressor 92 may be entirely
conventional (for instance they may correspond to those of a known compressor) and
therefore will not be described in further detail.
The inboard portion 110 of the bearing housing 4 (see below) and the turbine 9 1
together form a variable geometry turbine assembly according to a first embodiment of
the invention.
The present invention is suitable for, but not limited to, a turbocharger. However, since
the invention relates to the nature of a variable geometry turbine assembly, other
details of a turbocharger incorporating the variable geometry turbine assembly of the
present invention, such as other details of the bearing housing 4 and the compressor 3
will not be described in any further detail.
The turbine housing 2 comprises an inlet portion 120 and an outlet portion 121 which
define the inlet volute 8 and the axial outlet passageway 9 respectively. The inlet
portion 120 is attached to an axially inboard portion 110 (see figure 18) of the bearing
housing 4 by a plurality of circumferentially spaced bolts 112. It will be appreciated that
the turbine housing 2 may be fixedly attached to the bearing housing 4 by any suitable
means of attachment, including by a V- band.
An annular cavity 24 is defined between the inboard section 110 of the bearing housing
4 and the inlet portion 120 of the turbine housing 2 . The annular cavity 24 is
substantially centred on the turbocharger axis 5a.
The variable geometry turbine 9 1 comprises an annular shroud 11 (as shown in more
detail in figures 11 to 13). The shroud 11 is generally annular and is substantially
centred on the turbocharger axis 5a. The shroud 11 comprises a radial annular wall 18
that has a radial inboard surface 12 and a radial outboard surface 20. The inboard and
outboard radial surfaces 12, 20 are generally annular, are substantially centred on the
turbocharger axis 5a and extend in the radial direction, substantially perpendicular to
the turbocharger axis 5a.
The annular wall 18 is provided with a plurality of slots 16, wherein each slot 16 is
arranged to receive a respective guide vane 15 of the nozzle ring 13 as the shroud 11
is moved axially relative to the nozzle ring 13 (see below).
The annular wall 18 forms a movable wall member to vary the width of the inlet
passageway (as described in more detail below).
The shroud 11 further comprises an axially extending annular flange 19 that extends, in
the axially outboard direction, away from the outer radial periphery of the axially
outboard surface 20 of the shroud 11. The axially extending annular flange 19 is
substantially parallel to the turbocharger axis 5a. The axially extending flange 19 has a
section 23 towards its outboard end that is of reduced thickness, such that it defines an
annular step.
The annular inlet passageway 10 is defined between the axially inboard surface 12 of
the shroud 11 and a facing inboard surface 17 of the turbine housing 2 . The facing
inboard surface 17 of the turbine housing 2 is generally annular, is substantially centred
on the turbocharger axis 5a and extends in the radial direction, substantially
perpendicular to the turbocharger axis 5a. As will be described in more detail below,
the shroud 11 is axially slidably mounted within the cavity 24, for axial movement
relative to the inboard surface 17 of the turbine housing 2 , so as to vary the width of the
inlet passageway 10.
In this respect, the width of the inlet passageway 10 is varied to optimise gas flow
velocities over a range of mass flow rates so that the power output of the turbine 9 1
can be varied to suit varying engine demands. For instance, when the volume of
exhaust gas being delivered to the turbine 9 1 is relatively low, the velocity of the gas
reaching the turbine wheel 6 is maintained at a level which ensures efficient turbine
operation by reducing the size of the annular inlet passageway 10.
The inboard surface 12 (and the outboard surface 20) of the radial wall 18 of shroud 11
is provided on the same axially inboard side of the annular inlet passageway 10 as the
bearing housing 4 .
The variable geometry turbine 9 1 further comprises a fixed nozzle ring 13 (as shown in
more detail in figures 6 to 8), mounted within the cavity 24. The nozzle ring 13 is
located within the radially outer, axially extending flange 19 of the shroud 11.
The nozzle ring 13 is generally annular and is substantially centred on the turbocharger
axis 5a. The nozzle ring 13 comprises an annular radially extending wall 25 having an
axially inboard surface 14 and an axially outboard surface 26. The inboard and
outboard surfaces 14, 26 extend in the radial direction, substantially perpendicular to
the turbocharger axis 5a.
A plurality of circumferentially distributed inlet vanes 15 extend axially inboard from the
inboard surface 14, into the annular inlet passageway 10. The vanes 15 each extend
axially inboard from a root, at said inboard surface 14, to a tip, distal to said inboard
surface 14. The inlet vanes 15 are arranged so as to deflect gas flowing through the
inlet passageway 10 towards the direction of rotation of the turbine wheel 6 .
In this respect, the radially extending wall 25 of the nozzle ring 13 is disposed axially
outboard of the radial wall 18 of the shroud 11, with the inlet vanes 15 of the nozzle
ring 13 extending through axial slots 16 in the radial wall 18 of the shroud 11, into the
annular inlet passageway 10.
The nozzle ring 13 is fixed, both axially and rotationally, to the bearing housing 4 . In
this respect, an annular flange 28 extends from a radially outer section of the outboard
surface 26 of the nozzle ring 13 in the axially outboard direction. A radially inner
surface of the axially extending flange 28 is mounted on a radially outer surface 27
(see Figure 1) of the inboard portion 110 of the bearing housing 4 .
The nozzle ring 13 comprises an integral heat shield 3 1 formed by a radially inner
annular portion of the nozzle ring 13.
The heat shield 3 1 of the nozzle ring 13 extends radially inwardly from a radially inner
section of the inboard surface 14 of the radial wall 25 of the nozzle ring. The heat
shield 3 1 is bent in the axial and radial directions to form an axial section 3 11 and a
radial section 312. The axial section 3 11 extends from the radially inner periphery of
the radial wall 25 of the nozzle ring 13, in the axially inboard direction. The radial
section 312 is substantially axially aligned with the inboard surface 12 of the shroud 11.
The radial section 312 extends radially inwardly, from an inboard end of the axial
section 3 11, to substantially cover the region of the bearing housing 4 between the
bearing housing 4 and the turbine wheel 6 . Accordingly, the heat shield 3 1 protects
this section of the bearing housing 4 from the hot exhaust gases in the turbine 2 . The
heat shield is made of a heat resistant material in the form of stainless steel (e.g. 304
or pl33) or Inconel. It will be appreciated that any suitable heat resistant material may
be used.
The nozzle ring 13 is axially fixed to a support member 32, as described in more detail
below.
The support member 32 is a substantially annular ring that is centred on the
turbocharger axis 5a. The support member 32 is shown in more detail in figures 4 , 9
and 10.
The support member 32 comprises a generally annular wall member 131 having
radially inner and outer annular surfaces 34, 33 respectively. The annular wall member
131 (and the radially inner and outer surfaces 34, 33) extend substantially parallel to
the axial direction 5a.
The support member 32 is substantially fixed in the axial direction. In this regard, the
radially inner surface 34 of the support member 32 is mounted on and axially (and
rotationally) fixed to the radially outer surface 27 of the bearing housing 4 .
The support member 32 is mounted on the bearing housing 4 with a slight radial
clearance from the radially outer surface 27 of the bearing housing in order to ensure
an axial sliding fit, for assembly. Tolerancing is applied to minimise 'slop' between
these two components due to thermal expansion.
The radially inner surface 34 is provided, substantially midway along its axial length,
with a radially inwardly extending annular flange 35. The support member 32 is
mounted on the radially outer surface 27 of the inboard portion 110 of the bearing
housing 4 . In more detail, a radially inner surface 132 of the annular flange 35 is
mounted on said radially outer surface 27 of the bearing housing 4 . The support
member 32 is mounted within the cavity 24, axially outboard of the radial wall 25 of the
nozzle ring 13. The annular flange 35 and the radially inner surface 34 of the support
member 32 form a stepped arrangement that is welded to a complimentary stepped
arrangement formed by the radially outer surface 29, and an axially outboard end, of
the axially extending flange 28 of the nozzle ring 13. In this way, the nozzle ring 13 is
fixedly attached, both axially and rotationally, to the support member 32. It will be
appreciated that the nozzle ring 13 may be fixedly attached to the support member 32
by any suitable means, including brazing.
An annular groove 36 is provided in the radially outer surface 27 of the inboard portion
110 of the bearing housing 4 (see Figure 1). An annular ring seal 37 is located within
the annular groove 36 and provides a seal between the radially outer surface 27 of the
bearing housing 4 and the radially inner surface 132 of the annular flange 35 of the
support member 32. This sealing arrangement prevents gas from flowing from the
annular inner passageway 10, passed the ring seal 37. This facilitates the
maintenance of a desired pressure differential across the radial wall 18 of the shroud
11. The seal 37 stops flow of gas into the cavity 24 between bearing housing and
nozzle ring, maintaining the pressure differential for load balance.
A resiliently deformable annular tolerance ring 38 (see Figures 1 and 2) is sandwiched
between the axially outboard side of the annular flange 35 of the support member 32
and an opposed surface of the bearing housing 4 . The tolerance ring 38 provides an
axially force inboard force to the nozzle ring 13 via the support member 32. In this
regard, as the turbine housing 2 is bolted onto the bearing housing 4 , the facing wall 17
of the turbine housing 2 exerts a force on the tips of the inlet vanes 15, and therefore
the nozzle ring 13, in the direction away from said facing wall 17, which acts to
compress the tolerance ring 38. This pre-loads the tolerance ring 38, which causes it to
exert a force in the opposite direction on the nozzle ring 13 via the support member 32,
which is free floating on the bearing housing 4 . In this regard, the support member 32 is
slidable mounted on the bearing housing 4 . This ensures that contact is maintained
between the tips of the inlet vanes 15 and said facing wall 14 regardless of turbine gas
pressure & pulsations. This also minimises the flow of gas over the tips of the vanes 15
at small diffuser passageway 10 widths, thereby improving efficiency.
The inboard surface 14 of a radially outer section of the annular wall 25 of the nozzle
ring 13 acts a stop that limits the axial position, in the outboard direction, of the shroud
11. In this regard, as the shroud 11 moves in the outboard direction (see below), the
outboard surface 20 of the annular wall 18 of the shroud 11 abuts the inboard surface
14 of a radially outer section of the annular wall 25 of the nozzle ring 13, thereby acting
as a stop to provide a desired maximum outboard position of the shroud 11.
The shroud 11 is moved in the axial direction, to vary the width of the annular inlet
passageway 10, by the use of an actuation mechanism, which will now be described in
detail.
The actuation mechanism comprises a carrier member 39, as shown in more detail in
figures 14 to 16. The carrier member 39 is a substantially annular ring that is
substantially centred on the turbocharger axis 5a. The carrier member 39 comprises
an annular wall 117 having radially inner and outer annular surfaces 40, 4 1. The
annular wall 117 extends substantially parallel to the axial direction 5a. In this regard,
the radially inner and outer surfaces 40, 4 1 of the annular wall 117 extend substantially
parallel to the axial direction 5a.
An annular flange 114 extends radially inwardly from the radially inner surface 40. The
annular flange 114 is substantially perpendicular to the axial direction 5a. An annular
groove 46 is provided in the annular flange 114.
The annular wall 117 has axially inboard and outboard sections 42, 45 disposed on
inboard and outboard sides of the annular flange 114. The outboard section 45 is of
greater thickness than the inboard section 42.
The carrier member 39 is fixed, both axially and rotationally, to the shroud 11.
Accordingly, as the carrier member 39 moves axially, the shroud 11 is moved axially
with the carrier member 39. The carrier member 39 is fixed directly to the shroud 11.
In this respect, a radially inner surface of the inboard section 42 of the annular wall 117
is welded to a radially outer surface of the outboard section of reduced thickness 23 of
the axial flange 19 of the shroud 11. It will be appreciated that carrier member 39 may
be fixedly attached to the shroud 11 by any suitable means, including brazing.
The annular wall 117 is provided with a plurality of radial bores 43. Specifically, the
annular wall 117 is provided with three radial bores 43 circumferentially distributed
about the annular wall 117. The radial bores 43 are equally circumferentially spaced
around the annular wall.
Each radial bore 43 extends radially inwardly from a first end provided in the radially
outer surface 4 1 of the carrier member 39, along a longitudinal axis that is substantially
parallel to the radial direction, to a second end. The longitudinal axis of each radially
extending bore is substantially straight.
Each radial bore 43 terminates before the radially inner surface 40 of the carrier
member 39 so that its second end is closed and forms a blind bore 43. Each bore 43
has a substantially circular cross-sectional shape about its longitudinal axis. Each bore
43 is for receipt of a substantially cylindrical pin 69 (as discussed in more detail below).
The axially outboard section 45 of the annular wall 117 is provided with a plurality of
axially extending recesses 44 distributed circumferentially about the annular wall 117.
When the carrier member 39 is mounted in position, one of its recesses is adjacent to
an arm 60 of a rotatable arm assembly 57 and provides clearance for the arm 60 to
rotate, as described in more detail below.
The carrier member 39 is slidably mounted on the radially outer surface 33 of the
support member 32 for movement in the axial direction. The carrier member 39 is
mounted directly on the support member 32. In more detail, a substantially annular
seal 44 is received within the annular groove 46 in the flange 114 of the carrier member
39 between the flange 114 and the radially outer surface 33 of the support member 32.
The annular seal 44 seals the carrier member 39 against the support member 32 as
the carrier member 39 moves axially relative to the support member 32. This prevents
gases flowing from the annular inlet passageway 10 axially outboard of the carrier
member 39, which helps to maintain a desired pressure differential across the carrier
member 39.
The actuation mechanism further comprises a cam member 47, as shown in more
detail in Figure 5 . The cam member 47 is a substantially annular ring that is
substantially centred on the turbocharger axis 5a. The cam member 47 comprises an
annular wall 104 having radially inner and outer annular surfaces 49, 48. The annular
wall 104 (and its radially inner and outer annular surfaces 49, 48) extends substantially
parallel to the axial direction 5a.
A plurality of slots 50 are provided in the annular wall 104 and are defined by
respective inner surfaces 5 1 of the annular wall 104. Each slot is generally elongate
and extends along a longitudinal axis 50a (see Figures 5 and 24a). Each slot extends
substantially through the radial thickness of the annular wall 104.
In the currently described embodiment there are three slots 50. Each slot 50 is
substantially identical. The slots 50 are distributed in the circumferential direction
around the annular wall 104, substantially equally spaced apart.
Each slot 50 extends in both the circumferential direction and the axial direction. In this
respect, each slot 50 defines a part of a helix about the turbocharger axis 5a.
Specifically, the longitudinal axis 50a of each slot 50 extends in both the circumferential
direction and the axial direction 5a. In this respect, the longitudinal axis 50a of each slot
50 defines a part of a helix about the turbocharger axis 5a.
In the embodiment of the cam member 47 shown in Figures 5 and 24a, the longitudinal
axis 50a of each slot 50 is inclined at a substantially constant angle relative to the
radial plane. In this respect, the radial plane is a plane that is substantially
perpendicular to the turbocharger axis 5a.
In the embodiment of the cam member 47 shown in Figures 24b and 24c, the
longitudinal axis 50a of each slot 50 is inclined at an angle relative to the radial plane
that varies along its length. This is advantageous in that it allows for a desired axial
movement of the shroud 11 for a certain rotational movement of the cam member 47.
In the embodiment of Figure 24b, the angle of the longitudinal axis 50a relative to the
radial plane decreases from a first end 501 of the slot 50 to a second end 502 of the
slot 50 such that slot 50 forms a concave curve.
In the embodiment of Figure 24c, the angle of the longitudinal axis 50a relative to the
radial plane increases and then decreases from the first end 501 of the slot 50 to the
second end 502 of the slot 50 such that the slot 50 forms a curved wave shape.
The cam member 47 is mounted for rotation about the turbocharger axis 5a. In this
regard, the cam member 47 is rotatably mounted on, and radially outwardly of, the
carrier member 39 and the axial extending flange 19 of the shroud 11. In this respect,
the radially inner surface 49 of the cam member 47 is mounted on the radially outer
surface 4 1 of the annular wall of the carrier member 39 and on an axial portion of the
radially outer surface 22 of the axially extending flange 19 of the shroud.
The radially inner surface 49 of the cam member 47 bears against the radially outer
surface 4 1 of the annular wall of the carrier member 39, as the cam member 47 rotates
and as the carrier member 39 moves axially.
The annular wall 117 of the carrier member 39 and the annular wall 104 of the cam
member 47 are substantially concentric with the turbocharger axis 5a.
The cam member 47 is sandwiched between opposed radially extending annular
surfaces 201 , 202 of the bearing housing 4 and turbine housing 2 respectively, such
that the cam member 47 can rotate about the turbocharger axis 5a but is substantially
fixed in the axial direction 5a, relative to the bearing and turbine housings 4 , 2 . The
slots 50 have substantially corresponding circumferential positions to the radial bores
43 in the carrier member 39. Said radial surfaces 201 , 202 are substantially
perpendicular to the axial direction 5a.
The inboard portion 110 of the bearing housing 4 comprises an annular wall member
53. The annular wall member 53 has an axially inboard, radially extending annular
surface 54. The surface 54 is substantially perpendicular to the axial direction 5a. An
annular flange 52 extends axially inboard from the surface 54. The annular flange 52
has radially outer and inner surfaces 151 , 153. The annular flange 52 is substantially
centred on the axis 5a of the turbocharger. A circumferentially extending gap 152 is
provided in the annular flange 52 so as to allow clearance for rotation of an arm 60 of a
rotatable arm assembly 57 (as described in more detail below).
A set of three axially extending slots 55 is provided in the axially extending flange 52,
distributed circumferentially about the annular flange 52. Each axial slot 55 is defined
by a respective inner surface 56 of the annular flange 52. Each axial slot 55 extends
axially outboard from the axially inboard end of the annular flange 52, forming an open
end at the outboard end of the annular flange 52. The slot 55 terminates within the
axial extent of the annular flange 52 so as to form a blind slot 55. Each axial slot 55
extends throughout the thickness of the annular flange 52, from its radially inner
surface 153 to its radially outer surface 15 1 . Each slot 55 is substantially straight in the
axial direction 5a. The longitudinal axis of each slot 55 does not extend in the
circumferential direction.
The cam member 47 is mounted radially inwardly of the annular flange 52. In this
respect, the radially outer surface 48 of the annular wall 104 of the cam member 47 is
disposed radially inwardly of the radially inner surface 153 of the annular flange 52 of
the bearing housing 4 , with a small radial clearance provided between said surfaces
48, 153. The arrangement is such as to allow for the rotation of the cam member 47
relative to the bearing housing 4 . Alternatively the radially outer surface 48 of the
annular wall 104 of the cam member 47 may bear against the radially inner surface 153
of the annular flange 52 of the bearing housing 4 .
The actuation mechanism further comprises a set of three pins 69. Each pin 69 is
generally elongate, extending along a longitudinal axis 118. Each pin 69 is
substantially straight. The longitudinal axis 118 of each pin is substantially straight and
is substantially parallel to the radial direction. Each pin 69 has a substantially circular
cross-sectional shape about its longitudinal axis.
Each pin 69 is received within a respective said radial bore 43 in the carrier member
39. Each pin 69 is axially fixed relative to the carrier member 39. In this respect, each
radially extending bore 43 has an axial extent that is substantially the same as, or
slightly greater than, the axial extent of the respective pin 69 such that as the pin 69 is
moved in the first and second axial directions, the carrier member 39 is moved in the
first and second axial directions respectively. It will be appreciated that the first and
second axial directions are the opposite directions parallel to the turbocharger axis 5a.
Each pin 69 protrudes radially outwardly from the respective bore 43 in the carrier
member 39 and passes through a respective said slot 50 in the cam member 47. The
pin 69 passes radially outwardly of the slot 50 into a respective said axial slot 55 in the
annular flange 52 of the wall member 53 of the bearing housing 4 .
Each pin 69 is slidable axially within the respective axial slot 55. However, the slot 55
is sized to substantially prevent rotation of the pin 69 about the turbocharger axis 5a.
In this respect, the slot 55 is of a width, in the circumferential direction, that is
substantially the same as that of the pin 69 such that the slot 55 prevents the rotation
of the pin 69 about the turbocharger axis 5a. Accordingly, due to the engagement of
the pins 69 within the radial bores 43 in the carrier member 39, the carrier member 39
is rotationally fixed relative to the bearing housing 4 , about the turbocharger axis 5a.
The method of operation of the actuation mechanism will now be described. In order to
move the shroud 11 axially, so as to vary the width of the annular inlet passageway 10 ,
the cam member 47 is rotated about the turbocharger axis 5a. This causes movement
of each slot 50 relative to the respective pin 69 that passes through the slot 50. Each
inner surface 5 1 of the cam member 47 that defines a respective slot 50 engages the
pin 69 received within the slot 50 and acts to move the pin 69 in the axial direction.
Due to the engagement of each pin 69 with the inner surface 56 of the annular flange
52 that defines the respective axial slot 55, the pin 69 is prevented from rotating. The
reaction force exerted by this inner surface 56 on the pin 69, in combination with the
force exerted on the pin by the rotating inner surface 5 1 that defines the respective slot
50, causes each pin 69 to move axially along the respective slot 56, in the inboard
direction.
Due to the engagement of each pin 69 within the radial bores 43 in the carrier member
39, this causes the carrier member 39, and therefore the shroud 11 (which is fixed to
the carrier member 39) to move in the axial direction. In this regard, the carrier
member 39 slides axially on the support member 32.
The support member 32 is made of stainless steel, coated with a low friction material
so as to facilitate the movement of the carrier member 39 over the support member 32.
The coating material is also wear resistant so as to prevent wear of the support
member 32 due to the movement of the carrier member 39 over it. In the described
embodiment the coating is CM1 1 or the support member is subject to a boronised heat
treatment.
Rotation of the cam member 47 in the anti-clockwise direction (when viewed looking
from the turbine end in Figure 2), acts to move the inboard surface 12 of the radial wall
18 of the shroud 11 towards the facing inboard surface 17 of the turbine housing 2 .
Rotation of the cam member 47 in the clockwise direction acts to move the inboard
surface 12 of the radial wall 18 of the shroud 11 away from the facing inboard surface
17 of the turbine housing 2 .
The actuation mechanism further comprises a rotatable arm assembly 57 mounted to
the bearing housing 4 (the rotatable arm assembly 57 is shown in more detail in figures
22 and 23).
The rotatable arm assembly 57 comprises an elongate arm 60 that extends along a
longitudinal axis and is pivotally mounted to the axially inboard surface 54 of the axially
inboard wall member 53 of the bearing housing 4 . A first end of the arm 60 is provided
with an aperture 7 1 within which is received a first end of an elongate pin 59. The pin
59 extends along a longitudinal axis and passes through a generally cylindrical collar
6 1 which is received within a bore 62 in the axially inboard wall member 53. The collar
6 1 is rotationally fixed within the bore 62 by virtue of an interference fit.
The pin 59 is rotatable within the collar 6 1 . The arm 60 is rotatably fixed to the pin 59
so as to rotate with the pin 59. In this respect, the pin 59 forms an interference fit
within the aperture 7 1 in the first end of the arm 60.
A second end of the arm 60 is provided with an axially extending protrusion 58. The
protrusion 58 is generally cylindrical, having a substantially circular cross-section about
a longitudinal axis of the protrusion 58. The longitudinal axis of the protrusion 58 is
substantially perpendicular to the longitudinal axis of the arm 60. A second end of the
pin 59 is received within an aperture in an actuator arm 63. The second end of the pin
59 forms an interference fit with the aperture such that the pin 59 rotates with the
actuator arm 63.
The actuator arm 63 is disposed on an axially outboard side of the wall member 53 and
is connected to a pneumatic actuator (not shown). The actuator is arranged to rotate
the actuator arm 63 so as to rotate the pin 59 about its longitudinal axis, which rotates
the arm 60 about the longitudinal axis of the pin 59. The arm 60 and protrusion 58 are
mounted within a recess 400 in the flange 53 of the bearing housing, for rotation within
said recess 400. The recess 400 extends from the axially inboard surface of said flange
53, in the axially outboard direction and extends in the circumferential direction.
The recess 144 in the carrier member 39 that is proximal to the rotatable arm
assembly 57 provides a clearance for the arm 60 to rotate.
In addition, the circumferentially extending gap 152 in the annular flange 52 so allows
clearance for the arm 60 to rotate.
The cam member 47 is provided with a radially extending protrusion 66 which
protrudes radially outwardly from the radially outer surface 48 of the cam member 47
(see Figure 5). The protrusion 66 has an inner surface 67 which defines a cavity 68.
The cavity 58 is sized and dimensioned to receive the axially extending protrusion 58 of
the arm 60.
The protrusion 58 of the arm 60 is received within the cavity 68 such that it is
rotationally fixed relative to the radial protrusion 66. Accordingly, the rotation of the
arm 60 rotates the protrusion 58, which, by virtue of its engagement within the cavity
68, rotates the cam member 47 about the turbocharger axis 5a. The arm 60 is
rotatable in either direction so as to rotate the cam member 47 in either rotational
direction about the turbocharger axis 5a. This rotation of the cam member 47 acts to
move the shroud 11 in either axial direction so as to vary the width of the annular inlet
passageway 10, as described above.
The variable geometry turbine 9 1 (including the cam member 47, the pins 69, the
carrier member 39, the support member 32, the shroud 11 and the nozzle ring 13) and
the annular axially extending flange 52 provided with said axial slots 55 together form a
turbine assembly.
The cam member 47, the pins 69, the carrier member 39, the support member 32, the
shroud 11 and the nozzle ring 13, together form a cartridge assembly 1400. The
cartridge assembly 1400 is easy to install and remove from the turbocharger 1 since it
may be installed and removed as a single piece. In this regard, in order to install the
cartridge assembly, the cartridge assembly is mounted in position on the bearing
housing 4 and the turbine housing 2 is then attached to the bearing housing 4 so as to
sandwich the cartridge assembly within the cavity 24, between the bearing housing 4
and the turbine housing 2 .
In order to facilitate the correct orientation of the cartridge assembly 1400, the nozzle
ring 13 is provided with a protrusion 124 (see Figure 8) that extends axially outboard
from the outboard surface 26 of the nozzle ring 13. The protrusion 124 is generally
elongate and has a generally semi-circular cross-sectional shape. The radially outer
surface 27 of the inboard portion 110 of the bearing housing 4 is provided with a
radially inwardly and axially outboard extending recess 64 defined by an inner surface
65. The recess 64 has a generally semi-circular cross-sectional shape. The recess 64
is arranged to receive the protrusion 124 on outboard surface 26 of the nozzle ring 13.
When the protrusion 124 is received within the recess 64, the nozzle ring 13 is
automatically aligned in its correct rotational orientation. Accordingly, the engagement
of the protrusion 124 and the recess 64 facilitates the correct rotational orientation of
the nozzle ring, and therefore of the entire cartridge assembly 1400.
The variable geometry turbine assembly of the invention provides for a relatively
compact variable geometry turbine 9 1 that is particularly suited for use on small
variable geometry turbochargers. In addition, since it only requires a relatively small
cavity to house the actuation mechanism, this reduces the pressure differential
experienced during filling and scavenging of the exhaust gas in the housing.
In addition, since it does not require the yoke and push rods of prior-art designs, it has
improved sealing and does not require water cooling.
Furthermore, the cartridge assembly may be easily and conveniently retro fitted to
existing turbines so as to convert them into variable geometry turbines. In this regard,
the bearing housing 4 of an existing turbine may be provided with said axial slots 55
and said cartridge assembly 1400 mounted in a cavity between the bearing housing
and turbine housing, to convert it into a variable geometry turbine.
Referring to Figures 25 to 46 there is shown a variable geometry turbocharger
comprising a variable geometry turbine assembly according to a second embodiment
of the present invention. The variable geometry turbocharger of the second
embodiment is identical to the variable geometry turbocharger 1 of the first
embodiment, except for the differences described below. Corresponding features are
given corresponding reference numerals.
The turbocharger of the second embodiment differs from that of the first embodiment in
that the axially extending slots 55 in the annular axially extending flange 52 of the
bearing housing 4 are located radially outwardly of their position in the first
embodiment.
Furthermore, the support member 32 is sealed against the bearing housing 4 in a
reciprocal manner to the first embodiment. In this regard, the annular flange 35,
provided on the radially inner surface 34 of the support member 32 is provided,
substantially midway along its length in the axial direction, with an annular groove 300
(see Figure 34). The annular groove 300 extends radially inwardly from the radially
inner surface of the annular flange 35 and extends, in the circumferential direction,
about the turbocharger axis 5A, substantially about the inner circumference of the
support member 32. An annular ring seal 301 (see Figure 25) is received within the
groove 300 and seals the support member 32 against the radially outer surface 27 of
the bearing housing 4 . In this regard, the annular groove 300 and seal 301 replaces
the annular groove 36 in the bearing housing and the annular seal 37 of the first
embodiment so as to provide an alternative sealing arrangement to seal the support
member 32 against the radially outer surface 27 of the bearing housing 4 .
The second embodiment of the turbocharger also differs from the first embodiment in
how the cam member 47 is coupled to the movable shroud 11. In this regard, the
axially extending annular flange 19 of the shroud 11 is provided, towards its inboard
end, with a plurality of circumferentially distributed radial bores 302. Each bore 302
extends from the radially outer surface 22 of the axially extending flange 19 to a radially
inner surface 303 of the axially extending flange 19 (see Figure 36). Each bore 302
extends from the radially outer surface 22 to the radially inner surface 303 along a
longitudinal axis that is substantially parallel to the radial direction. Each bore 302 has
a substantially circular cross-sectional shape (about its longitudinal axis). Each bore
302 is for receiving a respective said pin 69 (as described in more detail below).
In this embodiment, the carrier member 39 and the shroud 11 are not connected to
each other by the stepped arrangement 23 of the first embodiment. In this regard, the
axially extending flange 19 of the shroud 11 is of substantially uniform thickness across
its length in the axial direction and so is not provided with said section 23 that defines a
step.
Instead, the axial flange 19 of the shroud 11 extends inboard substantially across the
axial length of the carrier member 39. In this regard, respective axially inboard ends of
the axial flange 19 of the shroud 11 and of the radially outer surface 4 1 of the carrier
member 39 are substantially axially aligned. The radially outer surface 4 1 of the carrier
member 39 forms an interference fit with the adjacent radially inner surface 303 of the
axially extending flange 19 of the shroud 11.
The radial bores 43 in the annular wall 117 of the carrier member 39 are substantially
aligned in, the circumferential direction, with the respective bores 302 in the annular
flange 19 of the shroud 11. In addition, the slots 50 in the cam member 47 overlap the
radial bores 302, 43, in the axially extending flange 19 of the shroud 11 and in the
carrier member 39.
As with the first embodiment, each pin 69 is received within a respective radial bore 43
in the carrier member 39. In addition, in this embodiment, each pin 69 passes through
a respective said bore 302 in the axial flange 19 of the shroud 11. In this way, the
shroud 11 is coupled to the carrier member 39 due to said interference fit and due to
the pins 69 engaging in the bores 302 in the axial flange 19 of the shroud 11. In this
respect, each bore 302 in the flange 19 has a diameter that is substantially the same
(or slightly greater than) the diameter of the pins 69 so that as the pin 69 move in the
axial direction, the shroud 11 is also moved in the axial direction (i.e. the shroud 11 is
axially fixed relative to the pins 69).
The method of operation of the actuation mechanism is substantially the same as that
for the first embodiment. In this respect, the rotation of the cam member 47 causes
movement of each slot 50 relative to the respective pin 69 that passes through the slot
50. The inner surfaces 5 1 of the cam member 47, that define the slots 50, engage the
pins 69 so as to move them in the axial direction. The engagement of each pin 69 with
the inner surface 56 of the annular flange 52 that defines the respective axial slot 55 in
the bearing housing 4 prevents the pin 69 from rotating and guides the pin 69 in the
axial direction. The engagement of the pin 69 in the radial bores 43 in the carrier
member 39 causes the carrier member 39 (and therefore the shroud 11) to move in the
axial direction), with the seal 44 in the annular groove 46 in the carrier member 39
sliding across the radially outer surface of the support member 32. In addition, the
engagement of the pins 69 in the radial bores 303 in the shroud 11 also acts to move
the shroud 11 in the axial direction, so as to vary the width of the inlet passageway.
However, in this embodiment, the helical slots 50 are oriented in the opposite rotational
sense. Accordingly, rotation of the cam member 47 in the clockwise direction (when
viewed looking from the turbine end of Figure 26), acts to move the inboard surface 12
of the radial wall 18 of the shroud 11 towards the facing inboard surface 17 of the
turbine housing 2 .
In this embodiment, the radially extending protrusion 66 of the cam member 47 has
been replaced with a slot 304. The slot 304 extends radially inwardly, from the radially
outer surface 48 of the annular wall 104 of the cam member 47, to the radially inner
surface 49, along a longitudinal axis. The longitudinal axis is substantially parallel to
the radial direction. The slot 304 has a substantially rectangular cross-sectional shape
(with an open outboard side), about its longitudinal axis.
The slot 304 extends in the inboard axial direction from an axially outboard surface of
the annular wall 104 of the cam member 47 and terminates within the axial thickness of
said annular wall 104 such that the slot 304 is open at its axially outboard end and is
closed at its axially inboard end.
The axially extending protrusion 58 of the arm 60 is of a complimentary shape to that of
the slot 304 in the cam member 47. In this regard, the protrusion 58 has a curved
rectangular cross-sectional shape that forms an interference fit with the slot 304 such
that rotation of the protrusion 58 about the turbocharger axis, rotates the cam member
47 about the turbocharger axis.
The removal of the radially extending protrusion 66 of the cam member 47 of the first
embodiment advantageously reduces the weight of the actuation mechanism.
As shown in Figure 37, an outboard end of the axially extending flange 19 of the
shroud 11 is provided with a slot 305 (see Figure 37). The slot extends axially inboard
from the outboard end of the flange 19 and extends in the circumferential direction, part
way along the circumference of the flange 19. The slot is adjacent to the arm 60 of the
rotatable arm assembly 57 and provides clearance for the arm 60 to rotate.
Referring to Figures 47 to 70 there is shown a variable geometry turbocharger
comprising a variable geometry turbine assembly according to a third embodiment of
the present invention. The variable geometry turbocharger of the third embodiment is
identical to the variable geometry turbocharger of the second embodiment, except for
the differences described below. Corresponding features are given corresponding
reference numerals.
The turbocharger of the third embodiment differs from that of the second embodiment
in that the annular flange 52 is not provided with said axially extending slots 55.
Instead, the vanes 15 of the nozzle ring 13 and the slots 16 in the shroud 11 are
arranged such that the engagement of the vanes 15 within the slots 16 substantially
prevents the shroud 11, and carrier member 39, from rotating, as the pins 69 are urged
in both the axial and circumferential directions due to the rotation of the cam member
47. In this regard, the slots 16 have a complimentary shape to the vanes 15 . In a
similar manner to the second embodiment, rotation of the cam member 47 in the
clockwise direction (when viewed looking from the turbine end of Figure 48) , acts to
move the inboard surface 12 of the radial wall 18 of the shroud 11 towards the facing
inboard surface 17 of the turbine housing 2 .
In this embodiment, there are no said axial guide slots 55 provided in said bearing
housing. Accordingly, as the cam member 47 rotates, the pins 69 are not prevented
from rotating by said axial guide slots 55.
In this regard, the rotation of the cam member 47 (in the clockwise direction) causes
the inner surfaces 5 1 of the cam member that define the slots 50 to engage the
respective pins 69 such that the pins 69 are urged in the clockwise rotational direction
about the turbine axis. This acts to rotate the carrier member, and therefore the shroud
11 about the turbine axis (in said clockwise direction) . However, the engagement of the
vanes 15 within the slots 16 acts to limit the rotation of the shroud 11 and to guide the
shroud 11 in the axial direction. In this regard, as the shroud 11 moves axially, the slots
16 slide over the vanes 15 .
Due to the rotational force exerted on the shroud 11 by the cam member 47, via the
pins 69, the shroud 11 is rotated by a small amount such that, for each slot 16 , a
radially outer section of a surface of the shroud that defines the slot abuts a radially
outer surface the vane 15 received within the slot. This substantially closes the high
pressure side of the slot and substantially prevents exhaust gas on this side from
passing from the inlet passageway through the slots 16 .
Alternatively, the actuation mechanism may be arranged such that rotation of the cam
member 47 in the anti-clockwise direction (when viewed looking from the turbine end
of Figure 48) , acts to move the inboard surface 12 of the radial wall 18 of the shroud 11
towards the facing inboard surface 17 of the turbine housing 2 . In order to do this, the
rotational orientation of the helical slots may be reversed.
In this case, the rotation of the cam member 47 (in the anti-clockwise direction) causes
the inner surfaces 5 1 of the cam member that define the slots 50 to engage the
respective pins 69 such that the pins 69 are urged in the anti-clockwise direction about
the turbine axis. This acts to rotate the carrier member 39, and therefore the shroud 11
about the turbine axis (in said anti-clockwise direction). However, the engagement of
the vanes 15 within the slots 16 acts to limit the rotation of the shroud 11 and to guide
the shroud 11 in the axial direction.
Due to the rotational force exerted on the shroud 11 by the cam member 47, via the
pins 69, the shroud 11 is rotated by a small amount such that, for each slot 16, a
radially inner section of a surface of the shroud that defines the slot abuts a radially
inner surface the vane 15 received within the slot. This substantially closes the low
pressure side of the slot and substantially prevents exhaust gas on this side from
passing from the inlet passageway through the slots 16.
Accordingly, in this way, the actuation mechanism may be arranged in either rotational
sense to provide desired performance characteristics.
Furthermore, in this embodiment, the pins 69 are integrally formed with the carrier
member 39. In this regard, the pins 69 form part of the carrier member 39 and protrude
radially outwardly from a radially outer surface of the carrier member 39. As with the
preceding embodiments, the pins 69 each extend from a radially inner end to a radially
outer end along a longitudinal axis that is substantially parallel to the radial direction. In
this embodiment, each pin 69 has a cross-sectional shape, about its longitudinal axis,
that is of a generally square shape with curved corners. This shape advantageously
increases the contact area between the pins 69 and the surfaces 5 1 that define the
slots 50, which reduces the contact stresses between the pins 69 and said surfaces 5 1 .
In addition, since the pins 69 are integral with the carrier member 39 this facilitates
assembly of a cartridge assembly 1400, formed by the cam member 47, the pins 69,
the carrier member 39, the support member 32, the shroud 11 and the nozzle ring 13,
since this provides few separate components to have to bring together.
In this embodiment, the cam member 47 is of a thinner radial thickness compared to
that of the previous embodiments, but is provided with a plurality of lugs 320
circumferential distributed about the cam member 47 (see figure 48). The lugs 320 are
of greater thickness (in the radial direction) than the remaining sections of the cam
member 47 provided between the lugs 320. In this embodiment, the cam member 47 is
provided with three of said lugs 320, distributed in the circumferential direction.
Each lug 320 has an inner surface 5 1 that defines a respective said helical slot 50 for
receiving a respective said pin 69. An outboard end of each helical slot 50 is open, so
as to allow insertion of a respective said pin 69 (which is integral with the carrier
member 39) through the open end and into the slot 50.
Providing the lugs 320 of increased thickness advantageously increases the contact
area between the pins 69 and the inner surfaces 5 1 of the lugs 320, that define the
helical slots 15 . This advantageously reduces the contact stresses between the pins 69
and the inner surfaces 5 1 that define the helical slots 15. In addition, since the sections
of the cam member 47 between the lugs 69 are of reduced thickness compared to the
lugs 320, this reduces the overall weight of the cam member 47 (and therefore of the
turbocharger), than if said sections of the cam member 47 were of the same thickness
as the lugs 320.
Alternatively, instead of having pins 69 that are integral to the carrier member 39, the
pins 69 may be separate entities to the carrier member 39 and may be receivable
within bores 43 in the carrier member 39, as in the preceding embodiments.
In this embodiment, the carrier member 39 is attached to the shroud 11 as in the first
embodiment, i.e. the axially extending flange 19 of the shroud 11 has a section 23 (see
Figure 60) towards its outboard end that is of reduced thickness.
A radially inner surface of the inboard section 42 of the annular wall 117 of the carrier
member 39 is welded to a radially outer surface of the outboard section of reduced
thickness 23 of the axial flange 19 of the shroud 11. It will be appreciated that carrier
member 39 may be fixedly attached to the shroud 11 by any suitable means, including
brazing.
In this embodiment, the nozzle ring 13 is provided with a protrusion 124 for rotatably
orienting the nozzle ring 13 relative to the support member 32 (see Figure 54). The
protrusion 124 is substantially cylindrical and extends axially outboard, from the
outboard surface 14 of the annular wall 25 of the nozzle ring 13. A radially inner
surface of the annular wall member 131 of the support member 32 is provided with a
recess 315 for receipt of the protrusion 124 of the nozzle ring 13. The recess 315
extends axially inboard from an inboard end of said wall member 131 . The recess 315
has a complementary shape to that of the protrusion 124.
Similarly, the annular wall member 131 of the support member 32 is provided with a
cylindrical bore 316 that extends axially inboard from the axially outboard surface of the
annular wall member 131 .
An axially inboard surface of the bearing housing 4 is provided with a bore 318 that
extends in the axially outboard direction. The bore 318 is for receipt of a locating pin
317 (see Figure 58) that is also received within the bore 316 in the support member 32.
In this embodiment the seal 27, 301 of the preceding embodiments, that sealed the
radially inner surface of the support member 32 to the radially outer surface of the
bearing housing 4 is not present and the radially inner surface of the support member
32 forms a press fit engagement with the radially outer surface of the bearing housing
4 .
When the pin 317 is received within the bore 318 in the bearing housing and in the
bore 316 in the support member 32, the support member 32 is oriented correctly
relative to the bearing housing 4 . In addition, when the protrusion 124 of the nozzle ring
13 is received within the recess 315 in the support member 32, the nozzle ring 13 is
oriented correctly relative to the support member 32.
Accordingly, said protrusion 124, recess 3 15 , bore 3 16 , pin 3 17 and bore 3 18 provide a
means of correctly orienting (in the circumferential direction) both the support member
39 and the nozzle ring 13 (and therefore the shroud 11) relative to the bearing housing
4 , during assembly. This facilitates ease of assembly of the cartridge assembly 1400.
In this embodiment, the rotatable arm assembly 57 (see figures 69 and 70) is
substantially the same as in the preceding embodiments, except in that the protrusion
58 has a substantially square cross-sectional shape, with rounded corners. The slot
304 in the cam member 47 is a complementary square shape to the protrusion 58.
In this embodiment, the heat shield 3 1 is no longer integral with the nozzle ring 13, but
is a separate entity. The nozzle ring 3 1 is mounted on a radially outer surface of the
heat shield 3 1, between the radially outer surface of the heat shield 3 1 and axially
adjacent radially inner surfaces of the support member 32 and shroud 11.
An axially outboard end of a radially outer annular axially extending flange of the heat
shield 3 1 is provided with an annular, radially outwardly extending, lip 330. The lip 330
is disposed axially outboard of the tolerance ring 38, and is sandwiched between the
tolerance ring 38 and a contacting axially inboard surface of the support member 32.
An inboard side of the tolerance ring 38 contacts an inboard surface of the nozzle ring
13, which biases the vanes 15 of the nozzle ring 13 against the facing surface 17 of the
turbine housing.
Accordingly, in this embodiment, the tolerance ring 38 directly contacts the nozzle ring
13 to bias it in the axially inboard direction. The heat shield 3 1 is separate to the nozzle
ring 13 and is mounted to the bearing housing 4 such that its lip 330 is disposed axially
outboard of the tolerance ring 38. Accordingly, the tolerance ring 38 does not exert a
force on the heat shield 3 1 in the axially inboard direction (as in the previous
embodiments). This is advantageous in that, during assembly, the heat shield 3 1 is not
urged in the axially inboard direction (which would otherwise occur before the turbine
housing is attached to the bearing housing 4). Therefore the heat shield 301 does not
exert a force, in the inboard direction, on the turbine wheel 6 , which would be
undesirable.
The axially extending flange 52 of the bearing housing 4 is provided with three of said
circumferentially extending gaps 152, equally spaced in the circumferential direction.
This reduces the weight of the bearing housing 4 .
The method of operation of the actuation mechanism is substantially the same as that
for the preceding embodiment.
Referring to Figures 7 1 to 95 there is shown a turbocharger comprising a variable
geometry turbine assembly according to a fourth embodiment of the present invention.
The variable geometry turbocharger of the fourth embodiment is identical to the
variable geometry turbocharger of the third embodiment, except for the differences
described below. Corresponding features are given corresponding reference
numerals.
The turbocharger of the fourth embodiment differs from that of the third embodiment in
that the shroud 11 is formed from a radially outer, axially extending annular flange 501 ,
a radially inner axially extending annular flange 503 and a radially extending annular
wall 502 that connects inboard ends of the radially outer and inner axially extending
flanges 501 , 503.
An inboard radial surface of the radially extending annular wall 502 forms said inboard
surface 12 that defines the inlet passageway. In this regard, the radially extending
annular wall 502 forms the movable wall member and the radially outer, axially
extending annular flange 501 forms the carrier member. Accordingly, in this
embodiment the shroud 11 comprises the movable wall member and the carrier
member. As with the preceding embodiments, the inboard surface 12 is provided with
said plurality of slots 16 for receipt of the nozzle vanes 15.
The radially outer, axially extending flange 501 extends outboard from a radially outer
end of the annular wall 502. An inboard end of the axially extending flange 501 is
welded to said radially outer end of the annular wall 502.
In this embodiment, the pins 69 are integrally formed with the radially outer axially
extending flange 501 , towards an outboard end of said flange 501 . The pins 69 extend
radially outwardly from a radially outer surface 5 18 of said flange 501 .
The radially inner axially extending flange 503 has a radially inner surface 514 that is
mounted on a radially outer surface of the heat shield 3 1.
The nozzle ring 13 is mounted within the shroud 11. In this regard, the nozzle ring 13
comprises a radially extending wall 504, where the vanes 15 extend axially inboard
from an inboard surface 14 of the wall 504 (see Figure 74). The radially extending wall
504 is provided with a radially outer and inner annular grooves 505, 506 that each
house an annular seal 507, 508. The seals 507, 508 respectively seal the radial wall
504 of the nozzle ring 13 against a radially inner surface of the radially outer axially
flange 501 and against a radially outer surface of the radially inner axially extending
flange 503, as the shroud 11 moves axially, relative to the nozzle ring 13.
The seals 507, 508 advantageously prevent exhaust gas, that has passed through the
slots 16, from passing outboard of the seals 507, 508. Furthermore, the radially inner
seal 508 prevents this exhaust gas from passing to the turbine wheel.
The method of operation of the actuation mechanism is substantially the same as that
for the preceding embodiment.
In each of the described embodiments, the nozzle ring 13 and shroud 11 are mounted
on the same axial side of the inlet passageway. In combination with the actuation
mechanism of the above described embodiments, this advantageously produces a
compact arrangement and allows the actuation mechanism to be formed as a cartridge.
In each of the described embodiments, the carrier member 39 is annular and the cam
member 47 and the carrier member 39 axially overlap for at least one axial position of
the shroud 11. In combination with the actuation mechanism of the above described
embodiments, this advantageously produces a compact arrangement and allows the
actuation mechanism to be formed as a cartridge.
It will be appreciated that the cam member 47 and the carrier member 39 axially
overlap for a plurality of axial positions of the shroud 11.
In each of the described embodiments, the cam member 47 is disposed radially
outwardly of the shroud 11. In combination with the actuation mechanism of the above
described embodiments, this advantageously produces a compact arrangement and
allows the actuation mechanism to be formed as a cartridge.
It will be appreciated that numerous modifications to the above described variable
geometry turbine assembly may be made without departing from the scope of the
invention as defined by the claims.
In this regard, in the described embodiments the slots 50 in the cam member 47 each
form a formation and the pins 69 each form a co-operating formation that is coupled to
the carrier member 39 such that as the co-operating formation is moved in the axial
direction, the carrier member 39 is moved in the axial direction. In an alternative
arrangement to that described, the slots 50 may be provided in the carrier member 39,
with the cam member 47 provided with said pins 69 such that rotation of the cam
member 47 relative to the carrier member moves the carrier member 39 in the axial
direction.
It will be appreciated that the invention is not limited to the use of said pins 69 and slots
50. The pins 69 may be any radially extending formation and the slots 50 may be any
complimentary recess for receiving the radially extending formation.
In the described embodiments the slots 50 extend in both the circumferential direction
and the axial direction and the pins 69 are arranged to move along the slots 50.
Alternatively, or additionally, the pins 69 (or any radially extending formation) may
extend in both the circumferential direction and the axial direction (e.g. having a helical
shape), with the slots 50 being for receipt of the pins 69 such that rotation of the cam
member 47 moves the carrier member 39 in the axial direction.
The features of any of the described embodiments may be combined with the features
of any of the other described embodiments.
For example, in any embodiment, the pins 69 may be coupled to the shroud 11 as in
any other embodiment. For example, in the fourth embodiment the pins 69 are part of
the shroud 11. However, the pins 69 may not be part of the shroud and may instead
be received within bores in the shroud and/or carrier member 39 as in the first to third
embodiments.
The different shapes of the slots 50 in the cam member 47 that are shown in Figures
24a to 24c may be used for any of the described embodiments.
In the described embodiments the shroud 11 is axially movable and the nozzle ring 13
is axially fixed, relative to the bearing housing 4 . Alternatively, the nozzle 13 may be
axially movable and the shroud 11 fixed in the axial direction. In this case, the nozzle
ring 13 is attached to the carrier member 39, instead of the shroud 16 such that the
actuation mechanism moves the nozzle ring 13. In this case, the nozzle ring 13 and
shroud 13 may be mounted on opposite axial sides of the inlet passageway.
Both the shroud 13 and the nozzle ring 13 may be movable in the axial direction.
In the described embodiments the actuation mechanism is disposed within a cavity 24
between the bearing housing 4 and the turbine housing 2 , on the side of the bearing
housing 4 . Alternatively, the actuation mechanism may be provided in a cavity on the
turbine housing 2 side of the annular inlet passageway 10. The actuation mechanism
may be housed in any suitable location.
The second to the fourth embodiments may have features of the first embodiment of
the annular axially extending flange 52 of the bearing housing 4 provided with said
axially extending slots 55, with the pins 69 received within said slots 55.
In the described embodiments the carrier member 39 is disposed radially inwardly of
the cam member 47. Alternatively, the carrier member 39 may be disposed radially
outwardly of the cam member 47. In this case, the carrier member 39 may be attached
to the shroud 11 by any suitable arrangement, for example via a flange which extends
in the axial direction and the radially inwardly direction so as to pass over and around
the cam member 47 to the shroud 11.
Additionally, or alternatively, the axially extending flange 19 of the shroud may be
mounted radially outwardly of the cam member 47.
In the described embodiments the cam member 47 is provided with a set of three slots
50. Alternatively, the cam member 47 may be provided with only a single slot 50. The
cam member 47 may be provided with one or more said slots 50.
In this regard, the carrier member 39 may be provided with a corresponding number of
said radial bores 43. In relation to the first embodiment the annular axially extending
flange 52 of the bearing housing 4 may be provided with a corresponding number of
said axially extending slots 55 and with a corresponding number of said radial pins 69
protruding through the respective slots/bores.
In the first embodiment the axial slots 55 are provided in the annular axially extending
flange 52 of the bearing housing 54. Alternatively, the slots 55 may be provided in a
different housing of the turbocharger 1.
The rotatable arm assembly 57 may be mounted to any housing of the turbocharger 1.
In the described embodiments the nozzle ring 13 is provided with a plurality of inlet
vanes 15 and the shroud 11 is provided with a plurality of slots 16. Alternatively, the
nozzle ring may not be provided with said inlet vanes 15. In this case, the shroud 11
may not be provided with said slots 16.
The described variable geometry turbine assembly is described when used as part of a
variable geometry turbocharger 1. However, it will be appreciated that the variable
geometry turbine assembly may be used as part of any turbomachine and is not limited
to use with turbochargers. For example, the variable geometry turbine assembly of the
invention may be used as part of a power turbine, or any other turbomachine.
In the described embodiments the carrier member is coupled to the shroud, so that
axial movement of the carrier member causes axial movement of the shroud, by being
directly attached to the shroud. Alternatively, the carrier member may be so coupled to
the shroud by being indirectly connected to the shroud, for example via an intermediary
coupling member. The same applies to the coupling of the carrier member to the
nozzle ring, where the nozzle ring comprises the movable wall member.
The variable geometry turbine assembly may not comprise the support member 32. In
this case, the carrier member 39 may be axially slidably mounted on a housing of the
variable geometry turbine assembly, such as the bearing housing 4 .
In the described embodiment the nozzle ring is provided with said protrusion 124 for
receipt in said recess 64. Alternatively, or additionally, the cam member and/or the
support member may be provided with said protrusion.
The bearing housing may be cast around the support member 32. In order to do this,
the support member 32 would be placed into a casing mould and molten metal poured
around it. The support member 32 would then be machined in conjunction with the
bearing housing to help reduce tolerance stack-ups. The annular groove 36 and seal
37 may then be omitted as there is no longer a potential leakage path needing to be
sealed.
The facing inboard surface 17 of the turbine housing 2 may also be movable in the
axial direction so as to vary the width of the inlet passageway.

CLAIMS
1. A variable geometry turbine assembly comprising:
PCT/GB2015/051346
a turbine wheel mounted within a turbine housing for rotation about a turbine
axis;
an annular inlet passageway extending radially inwards towards the turbine
wheel;
the annular inlet passageway being defined between a surface of a movable wall
member and a facing wall;
the movable wall member being movable in the axial direction so as to vary the
size of the annular inlet passageway,
and an actuation mechanism arranged to move the movable wall member axially
relative to the facing wall;
the actuation mechanism comprising:
a carrier member, the carrier member being movable in the axial direction and
coupled to the movable wall member such that as the carrier member is moved in
the axial direction, the moveable wall member is moved in the axial direction
a cam member provided with at least one formation;
the carrier member being coupled to at least one co-operating formation such
that as the at least one co-operating formation is moved in the axial direction, the
carrier member is moved in the axial direction, wherein one of the at least one
formation and the at least one co-operating formation is a radially extending
formation and the other defines a complimentary recess for receiving the radially
extending formation, the at least one formation or the at least one co-operating
formation extending in both the circumferential direction and the axial direction;
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the actuation mechanism is arranged such that as the cam member is rotated
relative to the carrier member, the at least one formation and the at least one cooperating
formation engage such that the at least one co-operating formation is
moved in the axial direction, thereby moving the carrier member in the axial
direction, and thereby moving the movable wall member in the axial direction so
as to vary the size of the inlet passageway;
the turbine assembly further comprising a nozzle ring having a plurality of
circumferentially distributed inlet vanes and an annular shroud provided with a
plurality of slots for receiving the inlet vanes of the nozzle ring as the shroud is
moved axially relative to the nozzle ring;
wherein the shroud comprises the movable wall member;
and the nozzle ring and shroud are mounted on the same axial side of the inlet
passageway.
2. A variable geometry turbine assembly according to claim 1 wherein the nozzle
ring comprises an annular radially extending wall, the plurality of
circumferentially distributed inlet vanes extend axially inboard from an inboard
surface of the radially extending wall and the annular shroud comprises an
annular radially extending wall provided with said plurality of slots, wherein the
radially extending wall of the nozzle ring is mounted axially outboard of the
radial wall of the shroud.
3. A variable geometry turbine assembly according to either of claims 1 or 2
wherein the variable geometry turbine assembly comprises a bearing housing
arranged to house at least one bearing that rotatably supports a shaft on which
the turbine wheel is mounted and the shroud and the nozzle ring are mounted
on the same axial side of the inlet passageway as the bearing housing.
4. A variable geometry turbine assembly comprising:
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a turbine wheel mounted within a turbine housing for rotation about a turbine
axis;
an annular inlet passageway extending radially inwards towards the turbine
wheel;
the annular inlet passageway being defined between a surface of a movable wall
member and a facing wall;
the movable wall member being movable in the axial direction so as to vary the
size of the annular inlet passageway,
and an actuation mechanism arranged to move the movable wall member axially
relative to the facing wall;
the actuation mechanism comprising:
an annular carrier member, the carrier member being movable in the axial
direction and coupled to the movable wall member such that as the carrier
member is moved in the axial direction, the moveable wall member is moved in
the axial direction;
a cam member mounted for rotation about the turbine axis;
the cam member is provided with at least one formation;
the carrier member being coupled to at least one co-operating formation such
that as the at least one co-operating formation is moved in the axial direction, the
carrier member is moved in the axial direction, wherein one of the at least one
formation and the at least one co-operating formation is a radially extending
formation and the other defines a complimentary recess to receive the radially
extending formation, the at least one formation extending in both the
circumferential direction and the axial direction;
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the actuation mechanism is arranged such that as the cam member is rotated,
the at least one formation and the at least one co-operating formation engage
such that the at least one co-operating formation is moved in the axial direction,
thereby moving the carrier member in the axial direction, and thereby moving the
movable wall member in the axial direction so as to vary the size of the inlet
passageway;
wherein the cam member and the carrier member axially overlap for at least one
axial position of the movable wall member.
5. A variable geometry turbine assembly according to claim 4 wherein the cam
member and the carrier member axially overlap for a plurality of axial positions
of the movable wall member.
15 6. A variable geometry turbine assembly according to either of claims 4 or 5
20
wherein the cam member is annular.
7. A variable geometry turbine assembly according to any of claims 4 to 6 wherein
the turbine assembly further comprises a nozzle ring having a plurality of
circumferentially distributed inlet vanes and an annular shroud provided with a
plurality of slots for receiving the inlet vanes of the nozzle ring as the shroud is
moved axially relative to the nozzle ring, wherein the nozzle ring or the shroud
comprises the movable wall member.
25 8. A variable geometry turbine assembly comprising:
30
35
a turbine wheel mounted within a turbine housing for rotation about a turbine
axis;
an annular inlet passageway extending radially inwards towards the turbine
wheel;
the annular inlet passageway being defined between a surface of a movable wall
member and a facing wall;
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the movable wall member being movable in the axial direction so as to vary the
size of the annular inlet passageway,
and an actuation mechanism arranged to move the movable wall member axially
relative to the facing wall;
the actuation mechanism comprising:
a carrier member, the carrier member being movable in the axial direction and
coupled to the movable wall member such that as the carrier member is moved in
the axial direction, the moveable wall member is moved in the axial direction
a cam member provided with at least one formation;
the carrier member being coupled to at least one co-operating formation such
that as the at least one co-operating formation is moved in the axial direction, the
carrier member is moved in the axial direction, wherein one of the at least one
formation and the at least one co-operating formation is a radially extending
formation and the other defines a complimentary recess for receiving the radially
extending formation, the at least one formation or the at least one co-operating
formation extending in both the circumferential direction and the axial direction;
the actuation mechanism is arranged such that as the cam member is rotated
relative to the carrier member, the at least one formation and the at least one cooperating
formation engage such that the at least one co-operating formation is
moved in the axial direction, thereby moving the carrier member in the axial
direction, and thereby moving the movable wall member in the axial direction so
as to vary the size of the inlet passageway;
wherein the cam member is disposed radially outwardly of the movable wall
member.
9. A variable geometry turbine assembly according to claim 8 wherein the cam
member and the movable wall member are annular.
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10. A variable geometry turbine assembly according to either of claims 8 or 9
wherein the turbine assembly further comprises a nozzle ring having a plurality
of circumferentially distributed inlet vanes and an annular shroud provided with
a plurality of slots for receiving the inlet vanes of the nozzle ring as the shroud
is moved axially relative to the nozzle ring, wherein the nozzle ring or the
shroud comprises the movable wall member.
11. A variable geometry turbine assembly according to any preceding claim
wherein the one of the at least one formation and the at least one co-operating
formation that extends in in both the circumferential direction and the axial
direction is said complimentary recess and the other is said radially extending
formation.
12. A variable geometry turbine assembly according to any preceding claim
wherein the at least one co-operating formation is said radially extending
formation and the at least one formation defines said complimentary recess to
receive the radially extending formation.
13. A variable geometry turbine assembly according to any preceding claim
wherein the at least one formation is said complimentary recess and extends in
both the circumferential direction and the axial direction and the at least one cooperating
formation is said radially extending formation.
14. A variable geometry turbine assembly according to any preceding claim
wherein the at least one co-operating formation is part of the carrier member.
15. A variable geometry turbine assembly according to any of claims 1 to 13
wherein the at least one co-operating formation is a separate entity to the
carrier member.
16. A variable geometry turbine assembly according to any preceding claim
wherein the at least one co-operating formation is a radially extending coupling
element.
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17. A variable geometry turbine assembly according to claim 16 wherein the carrier
member has an annular wall provided with at least one radially extending bore
and the at least one radially extending coupling element is received in the at
least one radially extending bore such that as the at least one coupling element
is moved in the axial direction, the carrier member is moved in the axial
direction.
18. A variable geometry turbine assembly according to any preceding claim
wherein the one of the at least one formation and the at least one co-operating
formation that extends in both the circumferential direction and the axial
direction defines at least part of a helix.
19. A variable geometry turbine assembly according to any preceding claim
wherein the one of the at least one formation and the at least one co-operating
formation that extends in both the circumferential direction and the axial
direction is substantially helical.
20. A variable geometry turbine assembly according to any preceding claim
wherein the at least one formation is said complimentary recess and extends in
both the circumferential direction and the axial direction and the at least one cooperating
formation is said radially extending formation and a wall member is
provided with at least one axially extending slot, the at least one co-operating
formation being received in the at least one axially extending slot and wherein
the actuation mechanism is arranged such that as the cam member is rotated
relative to the carrier member, the at least one formation and the at least one
co-operating formation engage such that the at least one co-operating formation
is moved in the axial direction, along the at least one axially extending slot in
said wall member, thereby moving the carrier member in the axial direction and
thereby moving the movable wall member in the axial direction, so as to vary
the width of the inlet passageway.
21. A variable geometry turbine assembly according to any preceding claim when
dependent on any of claims 1, 7 or 1 0 wherein the nozzle ring and shroud are
arranged such that as the shroud is moved axially, the engagement of the
vanes with the slots guides the shroud in the axial direction.
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22. A variable geometry turbine assembly according to claim 21 wherein the
engagement of the vanes with the slots limits the rotation of the shroud about
the turbine axis, as the shroud is moved in the axial direction.
23. A variable geometry turbine assembly according to either of claims 21 or 22
wherein the nozzle ring and shroud are arranged such that as the shroud is
moved axially, the engagement of the at least one formation and the at least
one co-operating formation rotates the shroud such that, for each slot in the
shroud, at least a portion of an inner surface that defines the slot abuts against
an opposed surface of a vane of the nozzle ring that is received within the slot.
24. A variable geometry turbine assembly according to any preceding claim
wherein the variable geometry turbine assembly comprises a bearing housing
arranged to house at least one bearing that rotatably supports a shaft on which
the turbine wheel is mounted and the shroud and the actuation mechanism is
mounted on the same axial side of the inlet passageway as the bearing
housing.
20 25. A variable geometry turbine assembly according to any preceding claim
wherein the at least one formation defines said complimentary recess and the
recess is provided in a circumferential section of the cam ring that is of greater
radial thickness than the remainder of the cam ring.
25 26. A variable geometry turbine assembly according to any preceding claim
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wherein the at least one formation defines said complimentary recess, the at
least one co-operating formation is said radially extending formation and is part
of the carrier member and the complimentary recess has an open end for
receipt of the co-operating formation.
27. A variable geometry turbine assembly according to any preceding claim
wherein at least one seal is provided between the carrier member and/or the
movable wall member and an adjacent surface such so as to substantially
prevent exhaust gas from the inlet passageway passing outboard of the seal.
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28. A variable geometry turbine assembly according to any preceding claim when
dependent on any of claims 1, 7 or 1 0 wherein the shroud comprises the
movable wall member and is slidably mounted in the nozzle ring, with the at
least one seal provided between a surface of the shroud and an opposed
surface of the nozzle ring.
29. A variable geometry turbine assembly according to any preceding claim any
preceding claim when dependent on any of claims 1, 7 or 1 0 wherein the
nozzle ring comprises a heat shield integrally formed with the nozzle ring and
disposed between the turbine wheel and a component of the variable geometry
turbine assembly, arranged to protect said component from the hot gases in the
turbine.
30. A variable geometry turbine assembly according to any preceding claim any
preceding claim when dependent on any of claims 1, 7 or 1 0 wherein the
variable geometry turbine assembly comprises a biasing member arranged to
bias the tips of the guide vanes into contact with the facing wall.
31. A variable geometry turbine assembly according to claim 30 when dependent
on claim 29 wherein the heat shield is not attached to the nozzle ring and the
biasing member is arranged to bias the tips of the guide vanes into contact with
the facing wall without exerting an inboard axial force on the heat shield.
32. A variable geometry turbine assembly according to any preceding claim
wherein the variable geometry turbine assembly further comprises a support
member comprising an annular wall, wherein the carrier member is axially
slidably mounted on a radially outer surface of the annular wall of the support
member.
30 33. A variable geometry turbine assembly comprising:
a turbine wheel mounted within a turbine housing for rotation about a turbine
axis;
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an annular inlet passageway extending radially inwards towards the turbine
wheel;
the annular inlet passageway being defined between a surface of a movable
wall member and a facing wall of a housing of the variable geometry turbine
assembly;
the movable wall member being movable in the axial direction so as to vary
the size of the annular inlet passageway,
and an actuation mechanism arranged to move the movable wall member
axially, relative to the facing wall of the housing;
the actuation mechanism comprising:
a carrier member, the carrier member being movable in the axial direction and
coupled to the movable wall member such that as the carrier member is
moved in the axial direction, the moveable wall member is moved in the axial
direction, the carrier member having an annular wall provided with at least one
radially extending bore;
at least one radially extending coupling element received in the at least one
radially extending bore in the annular wall of the carrier member such that as
the at least one coupling element is moved in the axial direction, the carrier
member is moved in the axial direction;
a cam member mounted for rotation about the turbine axis, the cam member
having an annular wall provided with at least one slot defined by at least one
surface of the annular wall, the at least one slot extending in both the
circumferential direction and the axial direction;
the at least one coupling element also being received in the at least one slot in
the cam member;
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wherein a wall member is provided with at least one axially extending slot, the
at least one coupling element also being received in at least one axially
extending slot;
and wherein the actuation mechanism is arranged such that as the cam
member is rotated about the turbine axis, the at least one slot in the annular
wall of the cam member is moved relative to the at least one coupling element,
with the at least one surface of the cam member that defines the at least one
slot acting on the at least one coupling element to move the at least one
coupling element in a the axial direction, along the at least one axially
extending slot in said wall member, thereby moving the carrier member in the
axial direction and thereby moving the movable wall member in the axial
direction, so as to vary the width of the inlet passageway.
15 34. A variable geometry turbine assembly according to claim 33 wherein the carrier
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member is axially fixed relative to the movable wall member.
35. A variable geometry turbine assembly according to either of claims 33 or 34
wherein the carrier member is arranged such that it is rotationally fixed about
the turbine axis.
36. A variable geometry turbine assembly according to any of claims 33 to 35
wherein the at least one radially extending bore in the annular wall of the carrier
member extends along a longitudinal axis that is substantially parallel to the
radial direction.
37. A variable geometry turbine assembly according to any of claims 33 to 36
wherein the at least one coupling element is axially fixed relative to the carrier
member.
38. A variable geometry turbine assembly according to claim 37 wherein the at
least one radially extending bore in the annular wall of the carrier member and
the at least one coupling element are arranged such that as the at least one
coupling element is moved in first and second axial directions, the carrier
member is moved in the first and second axial directions respectively.
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39. A variable geometry turbine assembly according to claim 38 wherein the at
least one radially extending bore has an axial extent that is substantially the
same as, or slightly greater than, the axial extent of the at least one coupling
element such that as the at least one coupling element is moved in the first and
second axial directions, the carrier member is moved in the first and second
axial directions respectively.
40. A variable geometry turbine assembly according to any of claims 33 to 39
wherein the cam member is rotationally mounted on, and supported for rotation
by, the carrier member.
41. A variable geometry turbine assembly according to any of claims 33 to 40
wherein the at least one coupling element is elongate, having a longitudinal axis
that is substantially parallel to the radial direction.
42. A variable geometry turbine assembly according to any of claims 33 to 41
wherein the cam member is rotationally mounted such that it is substantially
fixed in the axial direction as it rotates.
43. A variable geometry turbine assembly according to any of claims 33 to 42
wherein the at least one slot in the annular wall of the cam member is generally
elongate, extending along a longitudinal axis.
25 44. A variable geometry turbine assembly according to claim 43 wherein the
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longitudinal axis of the at least one slot is inclined at a substantially constant
angle relative to the radial plane.
45. A variable geometry turbine assembly according to claim 44 wherein the
longitudinal axis of the at least one slot may be inclined at an angle relative to
the radial plane that varies along its length.
46. A variable geometry turbine assembly according to any of claims 33 to 45
wherein the at least one axially extending slot may extend along a longitudinal
axis that does not extend in the circumferential direction.
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47. A variable geometry turbine assembly according to any of claims 33 to 46
wherein the at least one axially extending slot has a width in the circumferential
direction that is substantially equal to, or slightly greater than, the width of the at
least one coupling element in the circumferential direction such that the at least
one coupling element is prevented from moving in the circumferential direction
as it moves along the at least one axially extending slot.
48. A variable geometry turbine assembly according to any of claims 33 to 47
wherein the variable geometry turbine assembly comprises an annular wall
member, wherein the cam member is mounted radially inwardly of the annular
wall member such that a radially outer surface of the annular wall of the cam
member is opposed and adjacent to a radially inner surface of the annular wall
member and wherein the wall member that is provided with said at least one
axially extending slot is said annular wall member.
49. A variable geometry turbine assembly according to any of claims 33 to 48
wherein the at least one slot provided in the annular wall of the cam member,
the at least one radially extending bore provided in the annular wall of the
carrier member, the at least one axial slot provided in said wall member and the
at least one coupling element may be a plurality of said slots, radially extending
bores, axial slots and coupling elements respectively, wherein each coupling
element is received in a respective said radially extending bore in the carrier
member, in a respective said slot in the annular wall of the cam member and in
a respective said axially extending slot in said wall member.
50. A variable geometry turbine assembly according to any of claims 33 to 49
wherein the variable geometry turbine assembly further comprises a support
member comprising an annular wall, wherein the carrier member is axially
slidably mounted on a radially outer surface of the annular wall of the support
member.
51. A variable geometry turbine assembly according to claim 50 wherein the
support member and/or the carrier member are provided with a coating that
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acts to reduce friction between the carrier member and the support member
and/or that is resistant to wear.
52. A variable geometry turbine assembly according to either of claims 50 or 51
wherein the support member is substantially fixed in the axial direction.
53. A variable geometry turbine assembly according to any of claims 50 to 52
wherein the support member is mounted on a housing and at least one sealing
element is provided between the support member and the housing so as to
provide a seal between the support member and the housing.
54. A variable geometry turbine assembly according to any of claims 50 to 53
wherein at least one sealing element is provided between the carrier member
and the support member so as to provide a seal between the carrier member
and the support member as the carrier member moves axially relative to the
support member.
55. A variable geometry turbine assembly according to any of claims 33 to 54
wherein the variable geometry turbine assembly comprises a nozzle ring
provided with a plurality of guide vanes distributed circumferentially about the
nozzle ring that are receivable into the annular inlet passageway.
56. A variable geometry turbine assembly according to claim 55 wherein the nozzle
ring is axially fixed relative to the facing wall of the housing.
57. A variable geometry turbine assembly according to claim 55 wherein the nozzle
ring is axially and/or rotationally fixed to the support member.
58. A variable geometry turbine assembly according to any of claims 55 to 57
wherein the variable geometry turbine assembly comprises an annular shroud
having an annular wall provided with a plurality of slots, wherein each slot is
arranged to receive a respective guide vane of the nozzle ring to accommodate
relative axial movement between the shroud and the nozzle ring.
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59. A variable geometry turbine assembly according to claim 58 wherein the
moveable wall member is the annular wall of the shroud.
60. A variable geometry turbine assembly according to any preceding claim further
comprising an actuator coupled to the cam member so as to rotate the cam
member about the turbine axis.
61. A variable geometry turbine assembly according to claim 60 wherein the
actuator is coupled to the cam member by a rotatable arm, wherein the cam
member is provided with a formation that engages with the arm such that
rotation of the arm by the actuator rotates the cam member about the turbine
axis.
62. A variable geometry turbine assembly according to claim 61 wherein the carrier
member is provided with at least one recessed portion so as to provide
clearance for the rotation of the arm.
63. A variable geometry turbine assembly according to any of claims 55 to 62
wherein the nozzle ring comprises a heat shield integrally formed with the
nozzle ring and disposed between the turbine wheel and a component of the
variable geometry turbine assembly, arranged to protect said component from
the hot gases in the turbine.
64. A variable geometry turbine assembly according to any of claims 33 to 63
wherein the carrier member, movable wall member, cam member and the at
least one coupling element form a cartridge assembly.
65. A variable geometry turbine assembly according to any preceding claim
wherein a wall member of the variably geometry turbine assembly is provided
with a formation that is arranged to engage with a complimentary formation on
nozzle ring, the carrier member, the cam member and/or the support member
such that when the formations are engaged, the nozzle ring, carrier member,
cam member and/or the support member is in a specific rotational orientation
about the turbine axis.
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66. An actuation mechanism assembly comprising an actuation mechanism for
moving a movable wall member, a surface of which defines, with a facing wall,
an annular inlet passageway of a turbine, so as to vary the width of the annular
inlet passageway, the actuation mechanism comprising
a carrier member, the carrier member being movable in an axial direction and
coupled to the movable wall member such that as the carrier member is moved
in the axial direction, the moveable wall member is moved in the axial direction
a cam member provided with at least one formation;
the carrier member being coupled to at least one co-operating formation such
that as the at least one co-operating formation is moved in the axial direction,
the carrier member is moved in the axial direction, wherein one of the at least
one formation and the at least one co-operating formation is a radially extending
formation and the other defines a complimentary recess for receiving the
radially extending formation, the at least one formation or the at least one cooperating
formation extending in both the circumferential direction and the axial
direction;
the actuation mechanism is arranged such that as the cam member is rotated
relative to the carrier member, the at least one formation and the at least one
co-operating formation engage such that the at least one co-operating formation
is moved in the axial direction, thereby moving the carrier member in the axial
direction, and thereby moving the movable wall member in the axial direction so
as to vary the size of the inlet passageway;
the actuation member assembly further compns1ng a nozzle ring having a
plurality of circumferentially distributed inlet vanes and an annular shroud
provided with a plurality of slots for receiving the inlet vanes of the nozzle ring
as the shroud is moved axially relative to the nozzle ring;
wherein the shroud comprises the movable wall member;
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and the nozzle ring and shroud are mountable on the same axial side of the
inlet passageway.
67. An actuation mechanism for moving a movable wall member, a surface of which
defines, with a facing wall, an annular inlet passageway of a turbine, so as to
vary the width of the annular inlet passageway, the actuation mechanism
comprising:
an annular carrier member, the carrier member being movable in an axial
direction and for coupling to the movable wall member such that as the carrier
member is moved in the axial direction, the moveable wall member is moved in
the axial direction
a cam member mounted for rotation;
the cam member is provided with at least one formation;
the carrier member being coupled to at least one co-operating formation such
that as the at least one co-operating formation is moved in the axial direction,
the carrier member is moved in the axial direction, wherein one of the at least
one formation and the at least one co-operating formation is a radially extending
formation and the other defines a complimentary recess to receive the radially
extending formation, the at least one formation extending in both the
circumferential direction and the axial direction;
the actuation mechanism is arranged such that as the cam member is rotated,
the at least one formation and the at least one co-operating formation engage
such that the at least one co-operating formation is moved in the axial direction,
thereby moving the carrier member in the axial direction, and thereby moving
the movable wall member in the axial direction so as to vary the size of the inlet
passageway;
wherein the cam member and the carrier member axially overlap for at least
one axial position of the movable wall member.
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68. An actuation mechanism assembly comprising an actuation mechanism and a
movable wall member, wherein the actuation mechanism is for moving the
movable wall member, a surface of which is for defining, with a facing wall, an
annular inlet passageway of a turbine, so as to vary the width of the annular
inlet passageway, the actuation mechanism comprising:
a carrier member, the carrier member being movable in an axial direction and
coupled to the movable wall member such that as the carrier member is moved
in the axial direction, the moveable wall member is moved in the axial direction
a cam member provided with at least one formation;
the carrier member being coupled to at least one co-operating formation such
that as the at least one co-operating formation is moved in the axial direction,
the carrier member is moved in the axial direction, wherein one of the at least
one formation and the at least one co-operating formation is a radially extending
formation and the other defines a complimentary recess for receiving the
radially extending formation, the at least one formation or the at least one cooperating
formation extending in both the circumferential direction and the axial
direction;
the actuation mechanism is arranged such that as the cam member is rotated
relative to the carrier member, the at least one formation and the at least one
co-operating formation engage such that the at least one co-operating formation
is moved in the axial direction, thereby moving the carrier member in the axial
direction, and thereby moving the movable wall member in the axial direction so
as to vary the size of the inlet passageway;
wherein the cam member is disposed radially outwardly of the movable wall
member.
69. An actuation mechanism for moving a movable wall member, a surface of which
defines, with a facing wall of a housing, an annular inlet passageway of a
turbine, so as to vary the width of the annular inlet passageway, the actuation
mechanism comprising:
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a carrier member for coupling to a movable wall member, a surface of which
defines, with a facing wall of a housing, an annular inlet passageway of a
turbine, such that as the carrier member is moved in the direction of a
longitudinal axis of the carrier member, the moveable wall member is moved in
the axial direction, the carrier member having an annular wall provided with at
least one radially extending bore;
at least one radially extending coupling element being received in the at least
one radially extending bore in the annular wall of the carrier member such that
as the at least one coupling element is moved in the axial direction, the carrier
member is moved in the axial direction;
a cam member mounted for rotation about said axis, the cam member having
an annular wall provided with at least one slot defined by at least one surface of
the annular wall, the at least one slot extending in both the circumferential
direction and the axial direction;
the at least one coupling element also being received in the at least one slot in
the cam member;
the at least one coupling element being for receipt in at least one axially
extending slot in a wall member such that as the cam member is rotated about
said axis, the at least one slot in the annular wall of the cam member is moved
relative to the at least one coupling element, with the at least one surface of the
cam member that defines the at least one slot acting on the at least one
coupling element to move the at least one coupling element in a the axial
direction, along the at least one axially extending slot in said wall member,
thereby moving the carrier member in the axial direction and thereby moving
the movable wall member in the axial direction, so as to vary the width of the
inlet passageway.
70. A turbomachine comprising a variable geometry turbine assembly according to
any of claims 1 to 65.
71. A turbomachine according to claim 70 wherein the turbomachine is a
turbocharger, wherein the turbine wheel is mounted on a shaft, the turbocharger
comprising a compressor having an impeller wheel rotatably mounted within a
compressor housing and coupled to the shaft such that rotation of the turbine
wheel rotates the compressor wheel thereby drawing air in through an inlet of
the compressor, compressing the air and passing it to an outlet of the
compressor.
72. A variable geometry turbine assembly substantially as described herein with
reference to the accompanying drawings.
73. An actuation mechanism substantially as described herein with reference to the
accompanying drawings.
74. A turbomachine substantially as described herein with reference to the
accompanying drawings.