CLIAMS:CLAIMS:
1. A turbine comprising:
a turbine housing defining a turbine inlet upstream of a turbine wheel and a
turbine outlet downstream of the turbine wheel;
a wastegate passage connecting the turbine inlet and the 5 turbine outlet;
a wastegate valve comprising a movable valve member;
the wastegate valve having an open state in which gas may pass between the
turbine inlet and turbine outlet via the wastegate passage and a closed state in
which the valve member substantially prevents gas from passing between the
10 turbine inlet and the turbine outlet via the wastegate passage; and
wherein the valve member is mounted to an actuation member, the actuation
member passing through an actuator conduit of the turbine housing, and being
movable so as to move the wastegate valve between the open and closed
states;
15 the turbine further comprising a sealing arrangement configured to provide a
seal arranged to substantially prevent gas from passing from the turbine outlet
into the actuator conduit;
wherein the sealing arrangement is configured such that when the valve
member of the wastegate valve is urged into the closed state by the actuator
20 member the sealing effectiveness of the sealing arrangement is increased.
2. A turbine according to claim 1, wherein the wastegate valve further
comprises a valve seat, the valve member contacting the valve seat when the
wastegate valve is in the closed state; wherein the actuation member has a
longitudinal axis; and wherein the valve seat is angled relative to the
25 longitudinal axis and is configured such that when the actuation member urges
the valve member of the wastegate valve into the closed state, the valve seat
imparts a force on the valve member which urges the valve member in a first
substantially axial direction, and wherein the sealing arrangement is configured
such that the urging of the valve member in the first substantially axial direction
30 increases the sealing effectiveness of the sealing arrangement.
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3. A turbine according to either claim 1 or claim 2, wherein the valve member
comprises a surface configured such that, in use, when the wastegate valve is
in said open state, gas which passes through the wastegate passage is incident
on said surface of the valve member, and wherein the sealing arrangement and
valve member are configured such that gas incident on said 5 surface applies a
force to the valve member which increases the sealing effectiveness of the
sealing arrangement.
4. A turbine according to claim 3, wherein the actuation member has a longitudinal
axis and wherein a normal to said surface is non-perpendicular to the
10 longitudinal axis of the actuation member; and the valve member further being
configured such that, in use, when the wastegate valve is in said open state,
gas which passes through the wastegate passage is incident on said surface of
the valve member, the gas incident on said surface applying a force to the valve
member which urges the valve member in a first substantially axial direction
15 which increases the sealing effectiveness of the sealing arrangement.
5. A turbine according to any preceding claim, wherein the actuation member
rotates in order to move the wastegate valve between the open and closed
states.
6. A turbine according to claim 5, wherein the actuator rotates about its
20 longitudinal axis in order to move the wastegate valve between the open and
closed states.
7. A turbine according to any preceding claim, wherein the valve member is
mounted to the actuation member such that the valve member is located on a
first side of the actuator conduit, and a portion of the actuation member is
25 mechanically linked to an actuator or linkage configured to be linked to an
actuator, wherein the portion of the actuation member which is mechanically
linked to the actuator or linkage configured to be linked to the actuator is
located on a second side of the actuator conduit.
8. A turbine according to any preceding claim, wherein the sealing arrangement
30 comprises a seal member.
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9. A turbine according to claim 8, wherein the sealing arrangement is configured
such that the urging of the actuation member in the first substantially axial
direction compresses the seal member.
10. A turbine according to either claim 8 or claim 9, wherein the seal member is
disposed upon the 5 actuation member.
11. A turbine according to any of claims 8 to 10, wherein the seal member is
sandwiched between the valve member and the turbine housing.
12. A turbine according to any of claims 8 to 10, wherein the turbine further
comprises a bush, the bush being received by the actuator conduit and the
10 actuation member passing through the bush, and wherein the seal member is
sandwiched between the valve member and the bush.
13. A turbocharger or powerturbine including a turbine according to any preceding
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Turbine
The present invention relates to a turbine and in particular to a turbine having a
wastegate and sealing arrangement. The turbine may form part of a turbocharger or
5 power turbine.
Turbomachines are machines that transfer energy between a rotor and a fluid. For
example, a turbomachine may transfer energy from a fluid to a rotor or may transfer
energy from a rotor to a fluid. Two examples of turbomachines are a power turbine,
which uses the rotational energy of the rotor to do useful work, for example, generating
10 electrical power; and a turbocharger, which uses the rotational energy of the rotor to
compress a fluid.
Turbochargers are well known devices for supplying air to an inlet of an internal
combustion engine at pressures above atmospheric pressure (boost pressures). A
conventional turbocharger essentially comprises an exhaust gas driven turbine wheel
15 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 an engine inlet manifold. The turbocharger shaft is
conventionally supported by journal and thrust bearings, including appropriate
20 lubricating systems, located within a central bearing housing connected between the
turbine and compressor wheel housings.
The turbine of a conventional turbocharger comprises: a turbine chamber within which
the turbine wheel is mounted; an annular inlet defined between facing radial walls
arranged around the turbine chamber; an inlet volute arranged around the annular inlet;
25 and an outlet passageway extending from the turbine chamber. The passageways and
chamber communicate such that pressurised exhaust gas admitted to the inlet volute
flows through the inlet 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 so as to deflect gas flowing through the inlet. That is, gas
30 flowing through the annular inlet flows through inlet passages (defined between
adjacent vanes) which induce swirl in the gas flow, turning the flow direction towards
the direction of rotation of the turbine wheel.
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Turbines may be of a fixed or variable geometry type. Variable geometry turbines differ
from fixed geometry turbines in that characteristics of the inlet (such as the inlet’s size)
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 suit varying engine demands. For instance,
when the volume of exhaust gas being delivered to the turbine is relatively 5 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 inlet using a variable geometry
mechanism. Turbochargers provided with a variable geometry turbine are referred to
as variable geometry turbochargers.
10 Nozzle vane arrangements in variable geometry turbochargers can take different
forms. Two known types of variable geometry turbine are swing vane turbochargers
and sliding nozzle turbochargers.
Generally, in swing vane turbochargers the inlet size (or flow size) of a turbocharger
turbine is controlled by an array of movable vanes in the turbine inlet. Each vane can
15 pivot about an axis extending across the inlet parallel to the turbocharger shaft and
aligned with a point approximately half way along the vane length. A vane actuating
mechanism is provided which is linked to each of the vanes and is displaceable in a
manner which causes each of the vanes to move in unison, such a movement enabling
the cross sectional area available for the incoming gas and the angle of approach of
20 the gas to the turbine wheel to be controlled.
Generally, in sliding nozzle turbochargers the vanes are fixed to an axially movable
wall that slides across the inlet. The axially movable wall moves towards a facing
shroud plate in order to close down the inlet and in so doing the vanes pass through
apertures in the shroud plate. Alternatively, the nozzle ring is fixed to a wall of the
25 turbine and a shroud plate is moved over the vanes to vary the size of the inlet.
The compressor of a conventional turbocharger comprises a compressor housing
defining compressor chamber within which the compressor wheel is mounted such that
it may rotate about an axis. The compressor also has a substantially axial inlet
passageway defined by the compressor housing and a substantially annular outlet
30 passageway defined by the compressor housing between facing radially extending
walls arranged around the compressor chamber. A volute is arranged around the outlet
passageway and an outlet is in flow communication with the volute. The passageways
and compressor chamber communicate such that gas (for example, air) at a relatively
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low pressure is admitted to the inlet and is pumped, via the compressor chamber,
outlet passageway and volute, to the outlet by rotation of the compressor wheel. The
gas at the outlet is generally at a greater pressure (also referred to as boost pressure)
than the relatively low pressure of the gas which is admitted to the inlet. The gas at the
outlet may then be pumped downstream of the compressor outlet by 5 the action of the
compressor wheel.
It is known to provide a turbocharger turbine with a valve controlled bypass port
referred to as a wastegate, to enable control of the turbocharger boost pressure and/or
shaft speed. A wastegate valve (typically a poppet type valve) is controlled to open the
10 wastegate port (bypass port) when the boost pressure of the fluid in the compressor
outlet increases towards a pre-determined level, thus allowing at least some of the
exhaust gas to bypass the turbine wheel. Typically the wastegate port opens into a
wastegate passage which diverts the bypass gas flow to the turbine outlet or vents it to
atmosphere.
15 The wastegate valve may be actuated by a variety of means, including electric
actuators, but is more typically actuated by a pneumatic actuator operated by boost
pressure delivered by the compressor wheel. The wastegate valve actuator is typically
connected to the wastegate valve by a linkage, part of which passes through an
actuation conduit in the turbine housing. Where the linkage passes through the
20 actuation conduit it is possible that fluid from the turbine outlet may leak into the
actuation conduit and then to atmosphere. Leakage of fluid from the turbine outlet to
atmosphere may have an adverse effect on the performance of the turbine and hence
turbocharger.
It is an object of the present invention to provide a turbine which obviates or mitigates
25 at the above described disadvantage or other disadvantages present in the prior art.
According to a first aspect of the present invention there is provided a turbine
comprising a turbine housing defining a turbine inlet upstream of a turbine wheel and a
turbine outlet downstream of the turbine wheel; a wastegate passage connecting the
turbine inlet and the turbine outlet; a wastegate valve comprising a movable valve
30 member; the wastegate valve having an open state in which gas may pass between
the turbine inlet and turbine outlet via the wastegate passage and a closed state in
which the valve member substantially prevents gas from passing between the turbine
inlet and the turbine outlet via the wastegate passage; and wherein the valve member
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is mounted to an actuation member, the actuation member passing through an actuator
conduit of the turbine housing, and being movable so as to move the wastegate valve
between the open and closed states; the turbine further comprising a sealing
arrangement configured to provide a seal arranged to substantially prevent gas from
passing from the turbine outlet into the actuator conduit; wherein 5 the sealing
arrangement is configured such that when the valve member of the wastegate valve is
urged into the closed state by the actuator member the sealing effectiveness of the
sealing arrangement is increased.
The wastegate valve may further comprise a valve seat, the valve member contacting
10 the valve seat when the wastegate valve is in the closed state; wherein the actuation
member has a longitudinal axis; and wherein the valve seat is angled relative to the
longitudinal axis and is configured such that when the actuation member urges the
valve member of the wastegate valve into the closed state, the valve seat imparts a
force on the valve member which urges the valve member in a first substantially axial
15 direction, and wherein the sealing arrangement is configured such that the urging of the
valve member in the first substantially axial direction increases the sealing
effectiveness of the sealing arrangement.
The valve member may comprise a surface configured such that, in use, when the
wastegate valve is in said open state, gas which passes through the wastegate
20 passage is incident on said surface of the valve member, and wherein the sealing
arrangement and valve member are configured such that gas incident on said surface
applies a force to the valve member which increases the sealing effectiveness of the
sealing arrangement.
The actuation member may have a longitudinal axis and wherein a normal to said
25 surface is non-perpendicular to the longitudinal axis of the actuation member; and the
valve member further being configured such that, in use, when the wastegate valve is
in said open state, gas which passes through the wastegate passage is incident on
said surface of the valve member, the gas incident on said surface applying a force to
the valve member which urges the valve member in a first substantially axial direction
30 which increases the sealing effectiveness of the sealing arrangement.
The actuation member may rotate in order to move the wastegate valve between the
open and closed states.
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The actuator may rotate about its longitudinal axis in order to move the wastegate
valve between the open and closed states.
The valve member may be mounted to the actuation member such that the valve
member is located on a first side of the actuator conduit, and a portion of the actuation
member is mechanically linked to an actuator or linkage configured 5 to be linked to an
actuator, wherein the portion of the actuation member which is mechanically linked to
the actuator or linkage configured to be linked to the actuator is located on a second
side of the actuator conduit.
The sealing arrangement may comprise a seal member.
10 The sealing arrangement may be configured such that the urging of the actuation
member in the first substantially axial direction compresses the seal member.
The seal member may be disposed upon the actuation member.
The seal member may be sandwiched between the valve member and the turbine
housing.
15 The turbine may further comprise a bush, the bush being received by the actuator
conduit and the actuation member passing through the bush, and wherein the seal
member is sandwiched between the valve member and the bush.
According to a second aspect of the present invention there is provided a turbocharger
or powerturbine including a turbine according to the first aspect of the present
20 invention.
A specific embodiment of the present invention will now be described, by way of
example only, with reference to the accompanying drawings, in which:
Figure 1 shows a schematic cross-section through a portion of a known turbocharger;
Figure 2 shows a schematic perspective view of a portion of a turbocharger including a
25 turbine according to the present invention;
Figure 3 shows a schematic end-on perspective view of a portion of the turbocharger
shown in Figure 2;
Figure 4 shows a schematic cross-section through a portion of the turbocharger shown
in Figures 2 and 3;
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Figure 5 shows a schematic perspective view of a portion of the turbocharger shown in
Figure 2;
Figure 6 shows an schematic exploded perspective view of a valve member and
actuation member which forms part of the turbocharger in Figure 2;
Figure 7 shows a schematic cross-sectional view of a portion of 5 the turbocharger
shown in Figure 2, wherein a wastegate valve is in a closed state; and
Figure 8 shows a schematic cross-sectional view of a portion of the turbocharger
shown in Figure 2, wherein a wastegate valve is in an open state.
Figure 1 shows a schematic cross-section through a known turbocharger. The
10 turbocharger comprises a turbine 1 joined to a compressor 2 via a central bearing
housing 3. The turbine 1 comprises a turbine wheel 4 for rotation within a turbine
housing 5. Similarly, the compressor 2 comprises a compressor wheel 6 which can
rotate within a compressor housing 7. The compressor housing 7 defines a
compressor chamber within which the compressor wheel 6 can rotate. The turbine
15 wheel 4 and compressor wheel 6 are mounted on opposite ends of a common
turbocharger shaft 8 which extends through the central bearing housing 3.
The turbine housing 5 has an exhaust gas inlet volute 9 located annularly around the
turbine wheel 4 and an axial exhaust gas outlet 10. The compressor housing 7 has an
axial air intake passage 11 and a volute 12 arranged annularly around the compressor
20 chamber. The volute 12 is in gas flow communication with a compressor outlet 25. The
turbocharger shaft 8 rotates on journal bearings 13 and 14 housed towards the turbine
end and compressor end respectively of the bearing housing 3. The compressor end
bearing 14 further includes a thrust bearing 15 which interacts with an oil seal
assembly including an oil slinger 16. Oil is supplied to the bearing housing from the oil
25 system of the internal combustion engine via oil inlet 17 and is fed to the bearing
assemblies by oil passageways 18. The oil fed to the bearing assemblies may be used
to both lubricate the bearing assemblies and to remove heat from the bearing
assemblies.
In use, the turbine wheel 4 is rotated by the passage of exhaust gas from the exhaust
30 gas inlet 9 to the exhaust gas outlet 10. Exhaust gas is provided to exhaust gas inlet 9
from an exhaust manifold (also referred to as an outlet manifold) of the engine (not
shown) to which the turbocharger is attached. The turbine wheel 4 in turn rotates the
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compressor wheel 6 which thereby draws intake air through the compressor inlet 11
and delivers boost air to an inlet manifold of the engine via the volute 12 and then the
outlet 25.
The exhaust gas inlet 9 is defined by a portion of the turbine housing 5 which includes
a turbocharger mounting flange 27 at the end of the exhaust gas inlet 5 9 remote from
the turbine wheel 4.
Figures 2 to 5 show various schematic views of portions of a turbocharger 30 which
includes a turbine 32 in accordance with an embodiment of the present invention. The
turbocharger 30 includes all of the features of the turbocharger described above in
10 relation to Figure 1. The same numbering is used within Figures 2 to 5 for features of
the turbocharger 30 shown in Figures 2 to 5 which are equivalent to features shown in
the turbocharger of Figure 1.
In addition to the features of the turbine shown in Figure 1, the turbine according to an
embodiment of the present invention shown in Figures 2 to 5 also includes a wastegate
15 assembly. As can be seen best in Figure 4, the turbine 32 includes a turbine housing 5
which defines a turbine inlet 9 upstream of the turbine wheel 4, and a turbine outlet 10
downstream of the turbine wheel 4. The wastegate arrangement includes a wastegate
passage 34 (indicated schematically in dashed lines) which extends between the
turbine inlet 9 and turbine outlet 10, and hence connects the turbine inlet 9 with the
20 turbine outlet 10. The wastegate arrangement also includes a wastegate valve
comprising a movable valve member 36 and a valve seat 38. The valve seat 38 can be
seen best in Figure 5 in which the movable valve member of the wastegate valve is
omitted so as to aid the clarity of the figure.
The wastegate valve (and hence valve member 36) has an open state (as can be seen
25 in Figure 8) in which gas may pass between the turbine inlet 9 and turbine outlet 10 via
the wastegate passage 34. The wastegate valve (and hence valve member 36) also
has a closed state (as shown in Figures 3, 4 and 7) in which the wastegate valve
member 36 contacts the valve seat 38 and thereby in which gas is substantially
prevented from passing between the turbine inlet 9 and turbine outlet 10 via the
30 wastegate passage 34.
The valve member 36, which in this embodiment is of a poppet type, is mounted to an
actuation member 39 having a longitudinal axis A. The actuation member passes
through an actuator conduit 40 of the turbine housing 5. The actuation member 39 is
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movable so as to move the wastegate valve between the open and closed states and,
in particular, so as to move the valve member 36 between corresponding open and
closed states.
The actuation member 39 may be moved in any appropriate manner so as to move the
valve member 36 of the wastegate valve between the open and closed 5 states. In the
embodiment shown within Figures 2 to 8 this is achieved as follows. With particular
reference to Figures 2 and 6, the actuation member 39 includes a generally cylindrical
shaft 45 which extends along a longitudinal axis A. The shaft 45 of the actuation
member 39 is connected at a first end to the valve member 36. The shaft of the
10 actuation member 39 is connected at a second end to a lever arm 46. Within Figure 6,
the lever arm 46 is shown separated from the shaft 45 in order to aid the clarity of the
Figure. In present embodiment, the second end of the shaft 45 of the actuation
member is received by a recess 48 of the lever arm 46. Spaced from the recess 48
along the lever arm 46 is a stub 50. The stub 50 is received by a first end 52 of an
15 actuation rod 54. A second end (not shown) of the actuation rod 54 is connected to an
actuator 56 which is mounted to the turbine 32 via an actuator mounting arm 58.
In this embodiment, the actuator is a pneumatic actuator; however, any appropriate
actuator may be used. The mounting and operation of an actuator (and any associated
linkage) in order to move a valve member of a wastegate valve is well-known, and
20 hence further discussion of this is omitted within this description. However, it is worth
noting that movement of the actuator rod 54 causes the lever arm 46, and hence
attached shaft 45 of the actuation member 39, to pivot about axis A. The pivoting
movement of the shaft 45 of the actuation member 39 about the axis A results in the
valve member 36 also pivoting about axis A.
25 The shaft 45 of the actuation member is located within the actuator conduit 40 as
follows. A bush 74 is received by the actuator conduit 40 of the turbine housing 5. The
bush 74 is generally annular and the shaft 45 of the actuation member passes through
the central opening of the annular bush 74.
Within the embodiment of the invention shown in Figures 2 to 8, the annular seal ring
30 (or seal member) is disposed upon the shaft 45 of the actuation member and is
sandwiched between the valve member 36 and the bush 74. In other embodiments of
the present invention, such as those which do not include a bush which locates the
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actuation member within the actuator conduit, the seal member may be sandwiched
between the valve member and the turbine housing.
The valve member 36 is mounted to the actuation member such that the valve member
36 is located on a first side of the actuator conduit 40. A portion of the actuator
member is mechanically linked to a linkage (actuator lever 46 and 5 actuator rod 54)
configured to be linked to an actuator 56. The portion of the actuation member which is
mechanically linked to the linkage configured to be linked to the actuator 56, is located
on a second side of the actuator conduit 40. Within Figure 4, the first side of the
actuator conduit 40 is indicated generally by 70 and the second side of the actuator
10 conduit 40 is indicated generally by 72.
The valve member 36 can pivot about axis A between an open position as shown in
Figure 8 (in which the valve member 36 is spaced from the valve seat 38) and a closed
position as shown in Figure 7 (in which the valve member 36 contacts the valve seat
38).
15 Referring to Figures 7 and 8, it can be seen that, within the present embodiment, the
valve member 36 moves from the closed position shown in Figure 7 to the open
position shown in Figure 8 by moving upwards, via rotation of the shaft 45 of the
actuation member about axis A in the direction of arrow C. Conversely, in order to
move the valve member 36 from the open state of the wastegate valve shown in Figure
20 8 to a closed state corresponding to a closed state of the wastegate valve as shown in
Figure 7, the shaft 45 of the actuation member is rotated in the direction D about the
axis A.
The turbine of the present invention further includes a sealing arrangement 42 which is
configured to provide a seal arranged to substantially prevent gas from passing
25 between the turbine outlet 10 and the actuator conduit 40. In particular, the sealing
arrangement 42 is configured to provide a seal arranged to substantially prevent gas
from passing from the turbine outlet 10 into the actuator conduit 40. In the embodiment
shown, the sealing arrangement 42 includes an annular seal ring 44. It will be
appreciated that in other embodiments the sealing arrangement may have any
30 appropriate configuration provided that it is capable of substantially preventing gas
from passing between the turbine outlet and the actuator conduit.
The valve seat 38 is angled relative to the longitudinal axis A. This can be seen best in
Figures 4 and 7. Within these Figures it can be seen that the valve seat 38 is located
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in a plane which includes line B. The angle subtended between the longitudinal axis A
of the actuation member 39 and the valve seat 38 (i.e. between the longitudinal axis A
and the plane within which the valve seat 38 is located) is the angle which is
subtended between axis A and line B.
Due to the fact that the valve seat 38 is angled relative to the longitudinal 5 axis A of the
actuation member, when the actuation member urges the valve member 36 into the
closed state (as shown in Figure 7), the valve seat 38 imparts a force on the valve
member 36 which urges the valve member 36 in a first substantially axial direction E.
Likewise, when the actuation member urges the valve member 36 into the closed state,
10 the valve seat 38 imparts a force on the actuation member via the valve member 36
which urges the actuation member in the first substantially axial direction E.
In more detail, if the valve member 36 of the wastegate valve is in a closed state as
shown in Figure 7, and the valve member 36 is urged in the direction F by the rotation
of the shaft 45 of the actuation member in the direction D so as to effect movement of
15 the valve member 36 in to the closed state, the angled nature of the valve seat 38
relative to the longitudinal axis A of the actuation member will result in a reaction force
being applied by the valve seat 38 to the valve member 36 (and to the actuation
member via the valve seat 38) which has a component that urges the valve member
(and hence the actuation member) in the first substantially axial direction E.
20 The sealing arrangement 42 is configured such that the urging of the actuation member
in the first substantially axial direction E increases the sealing effectiveness of the
sealing arrangement. That is to say, urging of the actuation member in the first
substantially axial direction E will increase the effectiveness of the sealing arrangement
in substantially preventing gas from passing between the turbine outlet 10 and the
25 actuator conduit 40 (e.g. from the turbine outlet 10 into the actuator conduit 40). In the
present embodiment the urging of the actuation member in the direction E will increase
the sealing effectiveness of the sealing arrangement because urging the actuator
member in the direction E will result in the seal ring 44 of the sealing arrangement 42
being compressed, thereby increasing the sealing effectiveness of the seal ring 44.
30 The valve member and actuation member are also configured such that when the
wastegate valve (and hence valve member 36) is in the open state, the passage of gas
through the wastegate passage 34 also results in increased sealing effectiveness of
the sealing arrangement. This is achieved in this embodiment as follows. Referring to
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Figure 8, in use, gas passing through the wastegate passage 34 from the turbine inlet 9
to the turbine outlet 10 will flow in a general direction indicated by arrows G. The valve
member 36 comprises a surface 60. The normal N to the surface 60 when the valve
member 36 is in the open state (i.e. such that gas can flow through the wastegate
passage 34 between the turbine inlet 9 and turbine outlet 10) is non-5 perpendicular to
the longitudinal axis A of the actuation member.
In use, when the wastegate valve (and hence valve member 36) is in said open state,
gas which passes through the wastegate passage 34 is incident on the surface 60 of
the valve member 36 such that the gas incident on the surface 60 applies a force to the
10 valve member 36 which has a component which urges the valve member 36 and
actuation member in the first substantially axial direction E. As previously discussed,
urging the valve member 36 and actuation member in the first substantially axial
direction E will result in an increase in the sealing effectiveness of the sealing
arrangement in substantially preventing gas from passing between the turbine outlet 10
15 and the actuator conduit 40.
It is to be appreciated that numerous modifications to the above-described
embodiments may be made without departing from the scope of the invention as
defined in the appended claims.
Although the previous description is related to an embodiment of a turbine according to
20 the present invention which forms part of a turbocharger, it will be appreciated that a
turbine according to the present invention may form part of any appropriate
turbomachine. For example, a turbine according to the present invention may form part
of a turbomachine which does not include a compressor. In particular, a turbine
according to the present invention may form part of a power turbine, for example a
25 power turbine which converts the rotation of a turbine wheel into electrical power.
Although the above described embodiment relates to a turbine which operates in
conjunction with gas, it will be appreciated that turbines according to the present
invention may operate in conjunction with any appropriate fluid, for example a liquid.
The wastegate valve within the above described embodiment includes a poppet type
30 valve, which is actuated such that substantially linear movement of an actuator is
converted by a linkage to rotation of an actuator member which results in movement of
the valve member of the wastegate valve between open and closed positions. It will be
appreciated that any appropriate wastegate valve may be used, provided it has an
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open state in which gas may pass between the turbine inlet and turbine outlet via a
wastegate passage and a closed state in which gas is substantially prevented from
passing between the turbine inlet and the turbine outlet via the wastegate passage.
Likewise, any appropriate configuration of actuation of the wastegate valve may be
used provided it is capable of effecting a change of state of the 5 wastegate valve
between the open and closed states.
Although the above described embodiment includes a sealing arrangement which
comprises a seal ring, it will be appreciated that any configuration of seal arrangement
may be used, provided that the seal arrangement is arranged to substantially prevent
10 gas from passing between the turbine outlet and the actuator conduit, and provided
that the sealing effectiveness of the sealing arrangement increases when the
wastegate valve is urged into the closed state. For example, the seal arrangement may
comprise a seal member of any appropriate size and/or shape. Furthermore, the seal
member may be formed of any appropriate material.