BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
The present invention relates to a fluid machine such as
a scroll compressor, in particular, tc a scroll compressor
applied to a refrigerant compressor for a refrigeration
apparatus or an air conditioning apparatus.
This application is based on Japanese Patent Application
Nos. 2006-164 677, 2006-167903, and. 2,006-173897, the content of
which is incorporated herein by reference.
2. DESCRIPTION OF RELATED ART
Conventionally, a fluid machine such as a scroll
compressor that compresses gaseous fluid is commonly known.
As an example of this kind of fluid machine, there is a
fluid machine that is provided with a funnel-shaped lower
pressure side housing having a suction port for introducing
low pressure gaseous fluid, and a high pressure side housing
having a discharge opening for discharging high pressure
gaseous fluid, both housings being integrally connected to
form a sealed housing in which a compression mechanism such as
a scroll compression mechanism is accommodated. In this case,
the funnel shaped low pressure housing is constructed so that
a main body portion of the compression mechanism is arranged

on a large diameter wide opening section side, which is
connected to the high pressure housing, and a compression
mechanism driving section such as a rotation shaft is arranged
in a narrow section of small diameter (for example, refer to
the Publication of Japanese Patent No. 3227075 (FIG. 1)).
However, in the conventional fluid machine described
above, in order to secure the sectional area of a passage for
gaseous fluid to be introduced from a suction port provided in
the low pressure side casing into the interior of the
compression mechanism to be compressed, the dimension of a gap
section δ foirmed between an inner circumferential surface of
the low pressure side casing and an outer circumferential
surface of the compression mechanism needs to be set greater.
Since the diameter of the housing side is increased to secure
the required dimensions for this gap section δ, the outer
dimensions of the fluid machine increase by this amount,
becoming an obstacle to reducing the size of the fluid
machine.
Moreover, for example a body section of the low pressure
side casing is generally manufactured by aluminum die casting.
However, in this case, a corner section from a sidewall
surface to a bottom surface for securing strength may have a
curved surface of R0 radius. Therefore, as the gap section 5
described above, a gap section of at least δ0 (refer to FIG.
3B) for preventing interference between a body section 5A and

an orbiting scroll member 27 needs to be set starting at a
position on the flat surface at which the curved surface
finishes and a thrust receiving surface 5B begins. That is to
say, in order to avoid the orbiting scroll member interfering
with and riding up the curved surface of the corner section,
the gap section δ from the inner circumferential surface of
the body section 5A to a sliding range of the orbiting scroll
member 27 needs to be greater than δ0. This also results in an
inevitable increase in the outer dimensions of the fluid
machine. Since a small draft angle is provided in the
aluminum die casting body section 5A for the sake of
production convenience, the outline shape becomes larger as it
approaches the upper part of the sidewall surface. As a
result, the outline shape of the conventional fluid machine is
unnecessarily large.
In consideration of this background, a fluid machine
structure that enables a reduction in outer dimensions and
shape while securing sufficient sectional area of the passage
for introducing gaseous fluid introduced from the suction port
into the compression mechanism is desired.
Moreover, the scroll compressor is such that a stationary
scroll and an orbiting scroll are arranged so as to intermesh
with each other inside the housing. A plurality of
compression chambers are formed between the stationary scroll
and the orbiting scroll. The scroll compressor is constructed

such that the orbiting scroll is orbitally driven and the
compression chamber is shifted from its outer: circumferential
position to the center position while its capacity reduces to
compress a fluid.
In order to orbitally drive the orbiting scroll with
respect to the stationary scroll, a crankshaft is provided in
the housing allowing it to freely rotate around its axis. A
large diameter shaft section is provided on one end section of
this crankshaft. Furthermore, an eccentric pin that is
connected to the orbiting scroll via a drive bush and that
orbitally drives the orbiting scroll at a predetermined
rotation radius, is provided in the large diameter shaft
section. The large diameter section of the crankshaft is
supported by the housing. The large diameter shaft section is
supported in the housing via a main bearing constructed for
example from a ball bearing disclosed in the Publication of
Japanese No. 2868998. Thus, the crankshaft is supported,
allowing it to freely rotate around its axis.
A seal member that seals off (separates) the interior of
the housing from the outside, is provided on the other end
side of the crankshaft.
For example, in a scroll compressor used in a
refrigeration cycle, the refrigerant sucked in is introduced
between an inner ring and an outer ring of the bearing, and
lubrication oil contained in the refrigerant lubricates the

bearing.
In the case of the ball bearing, the components thereof
are in point-contact with each other (inner ring and ball,
ball and outer ring). Therefore, the ball bearing becomes a
comparatively large structure corresponding to the load to be
supported, and a gap for carrying out sufficient refrigerant
introduction into the interior can be secured. On the other
hand, if a ball bearing is used for the main bearing, there
will be a problem of an increase in the size of the housing.
In this kind of scroll compressor, a greatest reduction'
in size and weight possible is required for the sake of
installation.. Therefore, a main bearing that: uses a needle
shaped roller bearing having an outer ring to reduce the size
of the housing, as disclosed for example in Japanese
Unexamined Patent Application, Publication No. 2000--2250, has
been proposed.
However,, the gap within the interior of the needle shaped
roller bearing having an outer ring is small compared to a
ball bearing. As a result, if the needle shaped roller
bearing having an outer ring is used as a main bearing,
insufficient refrigerant is introduced into the bearing,
raising the possibility of insufficient lubrication for the
bearing.
For this reason, in a needle shaped roller bearing having
an outer ring, disclosed in Japanese Unexamined Patent

Application, Publication No. 2000-2250 the shape of an end
section in the axial direction of the outer ring is devised so
as to secure a gap for introducing refrigerant.
However, since the roller bearing disclosed in Japanese
Unexamined Patent Application, Publication No. 2000-2250 needs
to use a needle shaped roller bearing having an outer ring in
a special shape, there is a problem of an increase in
production cost.
Furthermore, a scroll compressor is disclosed in Japanese
Unexamined Patent Applications, Publication Nos. 2000-108647
and 2000-320477 in which a scroll compressor houses a scroll
compression mechanism constructed from a pair of a stationary
scroll member and an orbiting scroll member within a housing
constructed from a funnel shaped front housing and a rear
housing connected to a large diameter opening section of the
front housing', the stationary scroll member being fixed and
installed in the rear housing, a seal member being placed
between an end plate of the stationary scroll member and the
housing, the interior of the housing being separated into a
high pressure discharge chamber side and a low pressure intake
chamber side.
Here, the stationary scroll member is constructed from an
end plate and a spiral wrap standing upright on one side of
this end plate so that its axis is substantially orthogonal
thereto. In the same way, the orbiting scroll member is

constructed from an end plate and a spiral wrap standing
upright on one side of this end plate so that its axis is
substantially orthogonal thereto.
Moreover, a scroll compressor proposed in Japanese
Examined Patent Application, Publication No. Sho 60-17956,
that houses a scroll compression mechanism constructed from a
pair of a stationary scroll member and an orbiting scroll
member within a housing constructed from a cup shaped rear
housing and a front housing connected to a large diameter
opening section of this rear housing, employs the following
construction. Specifically, in Japanese Examined Patent
Application, Publication No. Sho 60-17956, there is proposed a
scroll compression mechanism capable of performing three
dimensional compression that enables compression in the
circumferential direction and in the wrap height direction, in
which step sections are respectively provided on a tip end
surface (the end surface facing the side opposite to the end
plate) and a bottom surface (area exposed to the space within
the spiral wrap on the end plate) of the respective spiral
wraps of the stationary scroll member and the orbiting scroll
member, and the wrap height on the outer circumference side of
the spiral wrap (length from the bottom surface to the tip end
surface of the spiral wrap) is higher than the wrap height on
the inner circumference side. Furthermore, in Japanese
Examined Patent Application, Publication No. Sho 60-17956,

there is proposed a construction in which the stationary
scroll member of the scroll compression mechanism is fixed and
installed on the rear housing side with a seal member placed
between the end plate of the stationary scroll member and the
housing, and the interior of the housing is separated to form
a high pressure discharge chamber side and a low pressure
intake chamber side.
However, in the scroll compressor disclosed in Japanese
Unexamined Patent Applications, Publication Nos. 2000-108647
and 2000-320477 mentioned above, a seal member that seals off
the interior of the housing from the atmospheric air is
arranged between the high pressure discharge chamber and the
atmospheric air. As a result, there is a problem in that high
pressure gas may leak directly into the atmospheric air in the
case where a failure occurs in the seal member or leakage
occurs due to an unusual rise in high pressure.
Moreover, the above seal member is arranged in a diameter
position substantially equal to that of the inner diameter of
the housing or the outer diameter of the end plate of the
stationary scroll member. According to such construction, a
high pressure load is applied on the entirety of the surfaces
of the housing and the stationary scroll member end plate, and
the area that receives pressure load due to this high pressure
is maximized. As a result, there is a possibility of gas
leakage due to minute deformation in the housing and the end

plate caused by excessive pressure load. Therefore, it is
necessary to increase the rigidity of the housing and the end
plate by increasing their plate thickness, resulting in an
increase in weight of the compressor that obstructs a
reduction in the weight of the compressor.
In addition, a scroll compressor disclosed in Japanese
Examined Patent Application, Publication, No. Sho 60-17956 has
a construction that does not allow direction leakage of high
pressure gas from the discharge chamber into the atmospheric
air, due to an arrangement and construction of the housing and
seal member mentioned above. However, since the above seal
member is arranged on the outer circumference of the end plate
of the stationary scroll member, there is no difference
whatsoever between the construction of Japanese Unexamined
Patent Application, Publication No. 2000-108647 and Japanese
Unexamined Patent Application, Publication No. 2000-320477
with respect to the area of portions of the housing and the
stationary scroll member end plate that receive pressure load
due to high pressure.
Therefore, problems related to gas leakage due to minute
pressure deformation, and an increase in the weight of the
compressor as a result of increasing the rigidity of the
housing and the end plate as a counter measure for the
leakage, are yet to be resolved in reality.
In particular, achieving a reduction in weight of a

compressor to be applied to an air conditioning apparatus for
a vehicle has been one of the most significant problems.
BRIEF SUMMARY OF THE INVENTION
In consideration of the circumstances described above, an
object of the present invention is to provide a fluid machine
able to secure a sectional area of a passage sufficient for
gaseous fluid flow from a suction port to the compression
mechanism, while able at the same time to achieve a reduction
in size of the outline shape.
Moreover, in consideration of the problems described
above, the present invention also aims to provide a scroll
compressor that can be manufactured inexpensively using a
generic needle shaped roller bearing having an outer ring, and
that can achieve a reduction in the size and weight of the
housing.
Moreover, the present invention is achieved in
consideration of such circumstances, and aims to provide a
reduced weight scroll compressor in which the housing
construction and arrangement of a seal member that seals off
between the atmospheric air and the housing, and between the
low pressure side and the high pressure side within the
housing are optimized to resolve gas leakage due to pressure
deformation in the housing and scroll members without
resorting to increasing their rigidity.

The present invention employs the following means to
solve the problems described above.
A fluid machine according to a first aspect of the
present invention is a fluid machine in which a compression
mechanism is housed and installed within a funnel shaped
housing, a compression mechanism main body of the compression
mechanism being arranged in a wide opening section of the
housing, and a compression mechanism driving section being
arranged in a narrow section, wherein a concave section is
formed on the outside of a compression mechanism support
surface, positioned on a bottom surface of the wide opening
section to support the compression mechanism.
According to such a fluid machine, since the concave
section is formed on the outside of the compression mechanism
support surface that is positioned on the bottom surface of
the wide opening section to support the compression mechanism,
this concave section functions as a passage for gaseous fluid.
Therefore, since the sectional area of the passage for gaseous
fluid increases, a diameter of the housing can be reduced by
reducing the dimension of a gap section 5.
In the first aspect of the present invention mentioned
above, it is preferable that the concave section and an
interior space of the narrow section be communicated with each
other. As a result, gas can be introduced into the
compression mechanism driving section to improve the cooling

and lubrication thereof.
In the first aspect of the present invention, it is
preferable that the concave section has an arc shape. As a
result, the strength in a corner section of a pressure
container can be secured easily, while the gap section 5 can
be set with hardly any influence from the curved surface of
the corner section.
In this case, it is preferable that the concave section
is formed by means of surface casting, thereby reducing the
number of processes.
In the above first aspect of the present invention, the
compression mechanism is a scroll compression mechanism, and
if the compression mechanism support surface is a thrust
receiving surface, burrs are unlikely to be produced when
machine processing the thrust receiving surface.
A fluid machine according to a second aspect of the
present invention is a fluid machine in which a compression
mechanism is housed and installed within a funnel shaped low
pressure side housing provided with a suction port, a
compression mechanism main body of the compression mechanism
being arranged in a wide opening section of the low pressure
side housing, and a compression mechanism driving section
being arranged in a narrow section, wherein a concave section
is formed on the outside of thrust receiving surface that is
positioned on a bottom surface of the wide opening section to

support the compression mechanism.
According to such a fluid machine, since the concave
section is formed on the outside of the thrust receiving
surface that is positioned on the bottom surface of the wide
opening section to support the compression mechanism, this
concave section functions as a passage for gaseous fluid.
Therefore, since the sectional area of the passage for gaseous
fluid increases, a diameter of the housing can be reduced by
reducing the dimension of a gap section 5.
According to the first and the second aspects of the
present invention mentioned above, since the sectional area of
the passage for gaseous fluid is secured by forming the
concave section on the outside of the thrust receiving section
that supports the compression mechanism, the diameter of the
housing can be reducing by reducing dimensions of the gap
section. Therefore, a fluid machine that sufficiently secures
the sectional area of the passage for introducing gaseous
fluid introduced from the suction port into the compression
mechanism while achieving a. reduction in outline size by
reducing the dimension of the gap section can be provided.
Moreover, in order to solve the above problems, the
present invention employs the following means.
That is to say, a scroll compressor according to a third
aspect of the present invention is a scroll compressor having:
a housing, and a compression mechanism, the compression

mechanism having a stationary scroll fixed and supported in
the housing, and an orbiting scroll that is intermeshed with
the stationary scroll to form a plurality of compression
chambers between the stationary scroll and the orbiting scroll
and that revolves; and further comprises; a crankshaft
provided with a large diameter shaft section having an
eccentric member for orbiting the orbiting scroll member,
provided on one end section, the large diameter shaft section
being freely rotatably supported on the housing via needle
shaped roller bearings having an outer ring; a seal member
arranged on an other end side of the crankshaft that seals off
the interior of the housing from outside; and a crank chamber
into which fluid containing lubrication oil is sucked,
provided between the orbiting scroll member and the large
diameter shaft section; wherein a position of the end section
on the one end side on a circumferential surface of the large
diameter shaft section is positioned to the other end side of
the position of the end section on the one end side of the
outer ring of the needle shaped roller bearing having an outer
ring.
In this way, since the end section position on the one
end side on the outer circumferential surface of the large
diameter shaft section is positioned on the other end side of
the position of the end section on the one end side of the
outer ring, a gap is formed between the one end side on the

outer circumferential surface of the large diameter shaft
section and the end section on the one end side of the outer
ring.
Since the fluid containing the lubrication oil introduced
into the crank chamber travels through this gap and is
introduced into the needle shaped roller bearing having an
outer ring, the needle shaped roller bearing having an outer
ring can be cooled by the fluid while being lubricated by the
lubrication oil.
In this way, since the gap for introducing fluid is
secured by determining the end section position on the one end
side on the outer circumferential surface of the large
diameter shaft section, a generic needle shaped roller bearing
having an outer ring can be employed, and production cost of
the scroll compressor can be reduced.
Furthermore, since the needle shaped roller bearing
having an outer ring is used, the housing can be made smaller
and lighter.
Moreover, in a third aspect of the above present
invention, it is preferable that the end section position on
the other end side on the outer circumferential surface of the
large diameter shaft section be positioned to the one end side
of the position of the end section on the other end side of
the outer ring.
As a result, since the fluid containing lubrication oil

travels through the gap formed between the other end side on
the circumferential surface of the large diameter shaft and
the end section on the other end side of the outer ring to be
supplied to the seal member, cooling and lubrication of the
seal member can be carried out even more reliably.
Moreover, a scroll compressor according to a fourth
aspect of the present invention is a scroll compressor having:
a housing, and a compression mechanism, the compression
mechanism having a stationary scroll fixed and supported in
the housing, and an orbiting scroll that is intermeshed with
the stationary scroll to form a plurality of compression
chambers between the stationary scroll and the orbiting
scroll, and that revolves; and further comprising: a
crankshaft with a large diameter shaft section having an
eccentric member for orbiting the orbiting scroll on one end
section, the large diameter shaft section being freely
rotatably supported on the housing via needle shaped roller
bearings having an outer ring; a seal member arranged on an
other end side of the crankshaft for sealing off the interior
of the housing from outside; and a crank chamber into which
fluid containing lubrication oil is sucked, provided between
the orbiting scroll member and the large diameter shaft
section; wherein the axial direction dimension of a
circumferential surface of the large diameter shaft section is
made shorter than the axial direction dimension of the outer

ring of the needle shaped roller bearing having an outer ring.
In this way, since the axial direction dimension of the
outer circumferential surface of the large diameter shaft
section is shorter than the axial direction dimension of the
outer ring, a gap is formed between at least the one end side
of the outer circumferential surface of the large diameter
shaft section and the end section on the one end side of the
outer ring.
Since the fluid containing the lubrication oil introduced
into the crank chamber travels through this gap and is
introduced into the needle shaped roller bearing having an
outer ring, the needle shaped roller bearing having an outer
ring can be cooled by the fluid while being lubricated by the
lubrication oil.
In this way, since the gap for introducing fluid is
secured by making the axial direction dimension of the outer
circumferential surface of the large diameter shaft section
shorter than the axial direction dimension of the outer ring,
a generic needle shaped roller bearing having an outer ring
can be employed and production costs of the scroll compressor
can be reduced.
Furthermore, since the needle shaped roller beairing
having an outer ring is used, the housing can be made smaller
and lighter.
In addition, since the gap can be formed between the

other end side of the outer circumferential surface of the
large diameter shaft section and the end section on the other
end side of the outer ring, depending on the axial direction
dimension of the outer circumferential surface of the large
diameter shaft section, the seal member can be cooled and
lubricated more reliably by the fluid containing lubrication
oil that has traveled through the gap.
Moreover, in the third and the fourth aspects of the
present invention described above, it is preferable that a
cutaway section, cut out from the outer circumferential
surface towards the one end section, be provided in the one
end section of the large diameter shaft section.
As a result, the axial direction length of the large
diameter shaft section can be secured while securing the gap
between the outer ring and the large diameter shaft section.
According to the third and the fourth aspects of the
present invention described above, the gap able to introduce
fluid between the one end side of the outer circumferential
surface of the large diameter shaft section and the end
section of the one end side of the outer ring, is secured by
prescribing the one end section position or the axial
direction length of the large diameter shaft section, and the
housing is provided with a boss section in which communication
holes that can be communicated with predetermined space
sections in the interior can be processed in a plurality of

places. As a result, a generic needle shaped roller bearing
having an outer ring is good enough to be employed, and hence
the scroll compressor can be inexpensively produced.
Moreover, in the third and the fourth aspects of the
present invention, since the needle shaped roller bearing
having an outer ring is used, the housing can be made smaller
and lighter.
Furthermore, in order to solve the above problems, the
scroll compressor of the present invention employs the
following means.
Specifically, a scroll compressor according to a fifth
aspect of the present invention is a scroll compressor
comprising: a housing; a scroll compression mechanism
constructed from a pair of a stationary scroll member and an
orbiting scroll member housed and installed within the
housing; and a driving shaft that orbitally drives the
orbiting scroll member of the scroll compression mechanism
housed and installed within the housing; wherein the housing
is constructed from a front housing and a rear housing that
covers a body section opening of the front housing that house
the scroll compression mechanism, the front housing having a
funnel shape and being provided with the large diameter body
section in which the scroll compression mechanism is
installed, and a driving shaft support section connected to
the body section and having a smaller diameter than that of

the body section, in which the driving shaft is installed; the
stationary scroll member has an end plate and a spiral wrap
standing upright on one side of this end plate so that its
axis is substantially orthogonal thereto; a first seal member
is placed in a position between the end plate and the inner
surface of the rear housing, on the inner circumference side
of the outer circumference of the end plate; the stationary
scroll member is fastened and fixed on the inner surface of
the rear housing via first bolts so as to separate off a
discharge chamber that discharges gas compressed in the scroll
compression mechanism, in an area on the inner circumference
side of the first seal member, together with the rear housing
and the first seal member; and the first seal member divides
the interior space of the housing into the discharge chamber
and an intake chamber formed within the space apart from the
discharge chamber.
According to a fifth aspect of the present invention, the
scroll compressor is constructed so that the stationary scroll
member is fastened and fixed on the inner surface of the rear
housing by first bolts with the first seal member placed
between an end surface on the inner circumference side of the
outer circumference of the end plate of the stationary scroll
member and the inner surface of the rear housing, thereby
separating the discharge chamber on the inner circumference
side of the first seal member. As a result, the area of the

portion of the end plate of the rear housing and the
stationary scroll member that receive a pressure load due to
high pressure can be made narrow. Accordingly, the end plate
of the stationary scroll member, the rear housing, and the
first bolts can be small.
In othe3: words, since the pressure load is reduced when
the pressure receiving area becomes smaller, the stress on the
members that receive pressure is reduced. Accordingly,
sufficient rigidity and strength can be secured even in a
structure having members that are made thinner and lighter, by
the amount by which the stress is thus reduced.
Moreover, the intake chamber is formed on the outer
circumference side of the first seal member that separates the
discharge chamber. As a result, even if gas leaks from the
discharge chamber, direct leakage of the gas into atmospheric
air can be prevented, and damage to the compressor due to an
unusual pressure rise can be prevented beforehand by leaking
the gas from the discharge chamber into the intake chamber
when unusually high pressure arises.
Furthermore, in a scroll compressor according to a fifth
aspect of the present invention, it is preferable to have a
construction in which the rear housing is fastened and fixed
on the opening section of the front housing by a second bolt
via a second seal member that seals from the atmospheric air,
and the second seal member seals off the intake chamber from

the atmospheric air on the outer circumference side of the
first seal number.
In other words, it is preferable to have a construction
where the rear housing is fastened and. fixed to the opening
section of the front housing by the second bolt via the second
seal member, which seals the connection section between the
rear housing and the front housing and which isolates the
interior of the housing from the atmosphere outside the
housing, and the second seal member isolates the intake
chamber from the atmosphere outside the housing on the outer
circumference side of the first seal member.
Since the second seal member seals off the intake
chamber, that is, a low pressure zone within the housing, from
the atmospheric air (atmosphere outside the housing}, a
pressure difference between the sealed spaces can be made
small. Therefore, a seal structure between these spaces can
be simplified, and the second bolt and fastening flanges that
fasten and fix the rear housing on the front housing can be
small.
Furthermore, in the scroll compressor according to the
fifth aspect of the present invention, it is preferable that a
spigot section that is fitted within the opening section of
the front housing be formed in the rear housing, and that the
rear housing be fastened and fixed onto the front housing by
the second bolt in a state where the spigot section is fitted

within the opening section.
In this case, since the spigot section is fitted inside
the opening of the front housing, the front housing can
suppress minute pressure deformation in the opening direction
of the rear housing. Therefore, gas leakage due to minute
pressure deformation of the rear housing, the stationary
scroll member, and so forth can also be suppressed.
Furthermore, it is preferable that the second seal member
be placed between the spigot section and the front housing.
In this case, since the second seal meinber is placed
between the spigot section and the front housing, even if
minute pressure deformation in the opening direction in the
rear housing occurs, the second seal member will be shifted
only in the axial direction by this. Therefore, sealing
functionality can be reliably secured.
Furthermore, the second seal member may be installed on
the spigot section side.
As described above, in the case where the second seal
member is installed on the spigot section side of the rear
housing, the second seal member can be easily held during
assembly simply by fitting it in the spigot section.
Furthermore, in the case where the second seal member is
installed in the spigot section of the rear housing in this
way, a minute gap may be formed between a mouth side (tip end
side) of an installation section of the second seal member in

the spigot section and the opening of the front housing.
In other words, the outer diameter of the spigot section
in the zone on the mouth side of the installation section of
the second seal member in the spigot section is smaller than
the inner diameter of the opening of the front housing, and
the minute gap may thereby be formed.
In this way, since the minute gap is formed on the mouth
side of the second seal member installation section in the
spigot section, the difference between the outer diameter of
the spigot section and the inner diameter of the second seal
member becomes small, enabling easier installation of the
second seal member to the spigot section. Moreover, on the
mouth side of the second seal member installation section in
the spigot section, a clearance for allowing relative movement
of the spigot section and the front housing is secured between
the spigot section and the opening of the front housing during
assembly of the scroll compressor, and fitting the spigot
section to the opening section of the front housing can be
carried out more easily.
Furthermore, the scroll compressor according to the fifth
aspect of the present invention may be such that: a spigot
section is formed in a position on the inner side of the outer
circumference side of the end surface on the end surface that
faces the rear housing side of the end plate of the stationary
scroll member; a section for fitting the spigot section is

formed in the inner surface of the rear housing; the spigot
section is fitted in the fitting section; the first seal
member is placed on the outer circumference side of this
fitting position; and the stationary scroll member is fastened
and fixed on the inner surface of the rear housing by the
first bolts via a screw boss section formed on the end surface
that faces the rear housing side of the end plate.
Hereinafter, a first construction of the fifth aspect of the
present invention refers to this construction.
In this way, by fitting the spigot section of the
stationary scroll member to the fitting section of the rear
housing and placing the first seal member on the outer
circumference side of the fitting position to install the
stationary scroll member, the stationary scroll member can be
accurately positioned with respect to the rear housing in
assembly regardless of the placing of the first seal member
and can be fastened and fixed by the first bolts.
Furthermore, the first seal member may be placed in a
corner section between the spigot section and the fitting
section. Here the corner section, in the spigot section
refers to an intersection section of an outer circumferential
surface and a wall surface that stands up towards the outer
circumference side from this outer circumferential surface,
while the corner section in the fitting section refers to an
intersection section of an inner circumferential surface and a

wall surface that stands up towards the outer circumference
side from this inner circumferential surface.
As described above, since the first seal member is held
in the corner section by placing the first seal member in the
corner section between the spigot section and the fitting
section, processing a seal groove for installation of the
first seal member is not required, and a cose reduction in
processing can be achieved as a result.
Furthermore, in the scroll compressor according to the
first construction of the fifth aspect of the present
invention, a thickness of the outermost circumferential
portion of the end plate on the outer circumference side of
the spigot section of the end plate of the stationary scroll
member may be formed thinner than that of other portions.
In this way, since the first seal member is placed in the
fitting position of the spigot section, a high pressure load
is not applied to the region on the outer circumference side
of the spigot section of the end plate. Therefore, the
thickness of the end plate outermost circumferential portion
on the outer circumference side of the spigot section can be
made thinner than that of other portions. Therefore, the
weight of the stationary scroll member can be reduced by an
amount corresponding to the volume of the reduced plate
thickness, and the weight of the scroll compressor can be
reduced in turn.

Furthermore, in the scroll compressor according to the
fifth aspect of the present invention, the construction of the
scroll compression mechanism may be such that the pair of the
stationary scroll member and the orbiting scroll member are
constructed so that the spiral wraps are provided standing
upright on the end plates, and respective step sections are
provided on the tip end surfaces of the respective spiral
wraps and on bottom surfaces of the end plates, the spiral
wrap height on the outer circumference side of the spiral wrap
being higher than the spiral wrap height on the inner
circumference side, so that three dimensional compression
capable of compressing in the circumferential direction and in
the wrap height direction can be performed. Hereinafter, a
second construction of the fifth aspect of the present
invention refers to this construction.
As described above, by increasing the spiral wrap height
of the stationary scroll member and the orbiting scroll member
on the outer circumference side, the compressor capacity can
be increased without increasing the scroll diameter. As a
result, a reduction in size and weight of the scroll
compressor can be achieved.
Furthermore, in the scroll compressor according to the
second construction of the fifth aspect of the present
invention, the screw boss section on which the first bolts are
fastened and fixed is formed on the end surface in a position

on the inner circumference side of the step section on the
bottom surface of the end plate of the stationary scroll
member.
In this way, since the screw boss section is formed in a
region where the plate thickness increases due to the
formation of the step section on the bottom surface of the
spiral wrap, the thickness of the end plate can be utilized to
provide a screw hole for the first bolt that requires an
engagement depth at least 1.5 times the screw diameter.
Accordingly, the axial direction dimension of the scroll
compressor, the minimum dimension being restricted to the
length of the first bolt, can be reduced, and the size and
weight of the scroll compressor can be reduced while improving
the mountability of the scroll compressor.
Furthermore, a screw hole for the first bolt may be
provided in the screw boss section so as to extend from the
bottom surface on the outer circumference side of the step
section towards the axial direction wrap side.
In this way, the axial direction dimension of the scroll
compressor, the minimum dimension being restricted to the
length of the first bolt, can be reduced to the greatest
possible extent by providing the screw hole that requires an
engagement depth of a predetermined length from the bottom
surface of the spiral wrap on the outer circumference side of
the step section towards the axial direction wrap side.

Furthermore, the screw boss section may be provided on
the inner circumference side of the first seal member.
In this way, since the screw boss section is provided on
the inner circumference side of the first seal member, and the
stationary scroll member is fastened and fixed in the screw
boss section by the first bolt, a force that acts on the first
seal member placed on the outer circumference side of the
screw boss section can be reduced. As a result, the lifetime
of the first seal member can be extended.
Furthermore, a clamping groove to be used during
processing of the stationary scroll member may be provided on
the outer circumference of the screw boss section.
In this way, since the clamping groove to be used in
processing the stationary scroll member is provided on the
outer circumference of the screw boss section, the stationary
scroll member can be stably clamped during processing using
this groove even when the plate thickness of the end plate
outermost circumference portion of the stationary scroll
member is made thin. Therefore, the stationary scroll member
can be processed to a high level of accuracy.
Furthermore, the groove may be provided around the entire
outer circumference of the screw boss section.
In this way, since the groove is provided around the
entire outer circumference of the screw boss section, the
weight of the stationary scroll member can be reduced by an

amount corresponding to the volume of this groove.
According to the fifth aspect of the present invention,
since the first seal member is placed between the end surface
on the inner circumference side of the outer circumference of
the end plate of the stationary scroll member and the rear
housing to separate the discharge chamber on the inner
circumference side of the first seal member, the area of the
stationary scroll member end plate and the rear housing that
bear a pressure load due to high pressure can be reduced.
Therefore, the stationary scroll member end plate, the rear
housing, and the first bolt that fastens and fixes them can
all be small, and the weight of the stationary scroll member,
the housing, and so forth can be reduced, thereby reducing the
weight of the compressor.
Moreover, since the intake chamber is formed on the outer
circumference side of the first seal member, even if gas
leakage from the discharge chamber occurs, direct leakage into
the atmospheric air can be prevented. At the same time, in
the case of an unusual pressure rise, damage to the compressor
due to an unusual rise in pressure can be prevented before it
occurs, by leaking compressed gas from the discharge chamber
into the intake chamber.
Moreover, the second seal member is placed between the
rear housing and the opening section of the body section of
the front housing to seal between the intake chamber and the

\atmospheric air between which the pressure difference is
small. As a result, a seal structure realized by the second
seal member can be simplified, and the second bolt and
fastening flange that fasten and fix the reatr housing on the
front housing can be small. Therefore, this also contributes
to a reduction in the weight of the housing so that the weight
of the compressor can be reduced.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 is a sectional view showing a construction of a
scroll compressor as a first embodiment of a fluid machine
according to the present invention.
FIG. 2 is a sectional view of FIG. 1 along the line A-A.
FIG. 3A is an enlarged sectional view of the essential
parts of a B section of FIG. 1.
FIG. 3B is a sectional view of the essential parts of a
conventional structure of the B section of FIG. 1.
FIG. 4 is a sectional view showing an overall schematic
construction of a scroll compressor according to a second
embodiment of the present invention.
FIG. 5 is a partial sectional view showing a relationship
between a needle bearing for a large diameter shaft section
and the large diameter shaft section according to the second
embodiment of the present invention.
FIG. 6 is a partial sectional view showing a portion

similar to that of FIG. 5.
FIG. 7 is a partial sectional view of a portion similar
to that of FIG. 5 showing another embodiment of the large
diameter shaft section according to the second embodiment of
the present invention.
FIG. 8 is a partial sectional view of a portion similar
to that of FIG. 5 showing yet another embodiment of the large
diameter shaft section according to the second embodiment of
the present invention.
FIG. 9 is a longitudinal sectional view showing a scroll
compressor according to a third embodiment of the present
invention.
FIG. 10A is an external perspective view showing a
stationary scroll member and an orbiting scroll member of the
scroll compressor shown in FIG. 9.
FIG. 10B is an external perspective view showing a
stationary scroll member and an orbiting scroll member of the
scroll compressor shown in FIG. 9.
FIG. 11 is a partial enlargement of a sectional view
showing the scroll compressor shown in FIG. 9.
FIG. 12 is a partial enlargement of a sectional view
showing a scroll compressor according to a fourth embodiment
of the present invention.
FIG. 13 is a partial enlargement of a sectional view
showing a stationary scroll member according to a fifth

embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[First embodiment]
Hereinafter, a first embodiment of a fluid machine
according to the present invention is described, with
reference to the drawings.
FIG. 1 is a sectional view showing a scroll compressor 1
used for compression of refrigerant gas or the like, as the
first embodiment of the fluid machine according to the present
invention.
The scroll compressor 1 shown in the diagram is a
horizontal type applied to a refrigeration apparatus or air
conditioning apparatus, in particular, to a refrigeration
apparatus or air conditioning apparatus for a vehicle, and has
a housing 3 that forms an approximate outline of the scroll
compressor 1 and that houses a compression mechanism in its
inside space. This housing 3 is provided with a low pressure
side front housing 5 and a high pressure side rear housing 7,
respective flange sections of which being integrally tightly
fastened to each other and fixed by bolts 9 only one shown.
Moreover, the compression mechanism of the scroll compressor 1
serves as a scroll compression mechanism 23, described later,
and is constructed from a compression mechanism main body and
a compression mechanism driving section.

A crankshaft 11 that constitutes the compression
mechanism driving section is supported within the front
housing 5 through a main bearing 13 and a sub bearing 15,
which allow it to rotate freely around an axis L. One end
side (left side in the diagram) of the crankshaft 11 is a
small diameter shaft section 11A. This small diameter shaft
section 11A passes completely through the front housing 5 and

projects towards the left side of FIG. 1. As is commonly
known, an electromagnetic clutch, a pulley and so forth (not
shown in the diagram) that receive motive power, are provided
on the projection section of the small diameter shaft section
11A, and power is transmitted thereto from a driving force
source (not shown in the diagram) such as an engine, via a V
belt.
Furthermore, a mechanical seal (lip seal) 17 is installed
between the main bearing 13 and the sub bearing 15 to air
tightly seal between inside the housing 3 and the atmospheric
air. That is to say, inside the housing 3 is isolated from
the atmospheric air by the mechanical seal provided between
the main bearing 13 and the sub bearing 15.
A large diameter shaft section 11B is provided on the
other end side (right side in the diagram) of the crankshaft
11, and an eccentric pin 11C, which is eccentric to the axis L
of the crankshaft 11 by a predetermined distance, is provided
integrally on this large diameter shaft section 11B. This

large diameter shaft section 11B and the small diameter shaft
section 11A are respectively supported within the front
housing 5 to allow free rotation through the main bearing 13
and the sub bearing 15. A drive bush 19 that: constitutes a
compression mechanism driving section together with the
crankshaft 11, and an orbiting scroll member 27 that
constitutes a compressor main body described later, are linked
to the eccentric pin 11C via a drive bearing 21 so that the
orbiting scroll member 27 is orbitally driven by rotation of
the crankshaft 11.
A balance weight 19A for canceling an unbalanced load
that occurs as a result of the orbital driving of the orbiting
scroll member 27, is formed integrally with the drive bush 19
so as to rotate together with the orbital driving of the
orbiting scroll member 27.
Moreover, a pair made of a stationary scroll member 25
and the orbiting scroll member 27 is fitted into the interior
of the housing 3 as the compression mechanism main body that
constitutes the scroll compression mechanism 23. The
stationary scroll member 25 is constructed from an end plate
25A and a spiral wrap 25B standing upright on the end plate
25A, and the orbiting scroll member 27 is constructed from an
end plate 27A and a spiral wrap 27B standing upright on the
end plate 27A.
The pair of the stationary scroll member 25 and the

orbiting scroll member 27 are fitted together in a state where
each of their centers is distanced from the other by the
turning radius amount, and where the spiral wraps 25B and 27B
are fitted with each other with a 180 degree phase shift. As
a result, a pair of compression chambers 29 limited by the end
plates 25A and 27A and the spiral wraps 25B and 27B, are
formed between both of the scroll members 25 and 27 in
symmetry with respect to the center of scroll. The stationary
scroll member 25 is fixed on an inner surface of the rear
housing 7 by a bolts 31, and the eccentric pin 11C provided on
one end side of the above crankshaft 11 is linked to a boss
section provided on a back surface of the end plate 27A so
that the orbiting scroll member 27 is orbitally driven.
The back surface of the end plate 27A of the orbiting
scroll member 27 is supported on a thrust receiving surface 5B
formed in the front housing 5. The orbiting scroll member 27
is prevented from rotating by a rotation prevention mechanism
33, such as a pin ring or an Oldham ring, that intervenes
between this thrust receiving surface 5B and the back surface
of the orbiting scroll member 27, to be orbitally driven
around the stationary scroll member 25.
An opening of a discharge port 25C for discharging
compressed refrigerant gas is provided in a center section of
the end plate 25A of the stationary scroll member 25, and a
discharge reed valve 37 attached to the end plate 25A via a

retainer 35 is provided in the discharge port 25C.
Furthermore, a seal member 39 such as an O-ring is placed on
the back surface side of the end plate 25A of the stationary
member 25 to make tight contact with the inner surface of the
rear housing 7, and a discharge chamber 41 separated from an
inner space of the housing 3, is formed between the back
surface side of the end plate 25A and the rear housing 7.
Accordingly, the inner space of the housing 3 apart from the
discharge chamber 41 is constructed to function as a low
pressure side intake chamber 43. The refrigeration gas
returning from the refrigeration cycle via a suction port 45
provided in the front housing 5 is sucked into the intake
chamber 43, and is sucked via the intake chamber 43 into a
compression chamber 29 formed between the stationary scroll
member 25 and the orbiting scroll member 27.
A seal member 47 such as an O-rir.g is placed on a joint
surface between the front housing 5 and the rear housing 7 to
air tightly seal the intake chamber 43 formed within the
housing 3 from the atmospheric air.
The scroll compression mechanism 23 is housed within the
front housing 5. This front housing 5 has a funnel shape, the
diameter of which reduces in phases, and is provided with: a
large diameter body section 5A for accommodating the
stationary scroll member 25 and the orbiting scroll member 27
of the compressor main body; a thrust receiving section 5C,

which continues from the body section 5A and has a reduced
diameter in the radial direction, for forming the thrust
receiving surface 5B; a medium diameter bearing support
section 5E, which continues from the thrust receiving section
5C, and which has its diameter further reduced, for forming a
bearing housing section 5D that houses the main bearing 13;
and a small diameter boss section 5F, which continues from the
bearing support section 5E, for installing the sub bearing 15
and the mechanical seal 17.
The rear housing 7 is of a dish shape and is pirovided
with a concave section 7A for forming the discharge chamber
41, and a spigot section 7B that fits with an aperture end of
the body section 5A of the front housing 5. The
aforementioned seal member 47 is placed in the spigot section
7B. This rear housing 7 is connected so as to cover one end
aperture of the body section 5A of the front housing 5, and
the flange sections of the front housing 5 and the rear
housing 7 are integrally tightly fastened and fixed by the
bolt 9.
Thus, the scroll compression mechanism 23 is housed
within the housing 3 having the funnel shaped front housing
(low pressure side housing) 5 provided with the suction port
45, the stationary scroll member 25 and the orbiting scroll
member 27 that constitute the compression mechanism main body
of the scroll compression mechanism 23 are arranged in the

space within the large diameter body section 5A that forms a
wide opening section of the front housing 5, and a compression
mechanism driving section of the scroll compression mechanism
23 comprising the crankshaft 11 and so forth is arranged in a
narrow inner space section of the bearing housing section 5D,
the diameter of which is smaller than that of the body section
5A. In this scroll compressor 1, a concave 5;ection 51 is
formed on the outside of the thrust receiving surface 5B which
is positioned on the bottom surface of the body section 5A and
which supports the scroll compression mechanism 23.
That is to say, since the above thrust receiving section
5C is positioned on the bottom surface of ths space formed as
the wide opening section within the body section 5A of the
front housing 5 formed in a funnel shape, the concave section
51 is formed on this thrust receiving section (bottom surface)
5C, on the outside of the thrust receiving surface 5B, in a
corner section where a wall surface that for:xis the body
section 5A meets the thrust receiving section 5C. This
concave section 51 is formed around the entire outer
circumference of the thrust receiving section 5C as shown in
FIG. 2. Furthermore, the concave section 51 is provided such
that an outer diameter of the thrust receiving section 5C,
that is, an inner diameter of the concave section 51 is within
a range in which the inner diameter of the concave section 51
is smaller than an envelope curve formed by an outline traced

when the orbiting scroll member 27 is driven, and such that
the outline of the concave section 51 is within a range where
the orbiting scroll member 27 does not come in contact with
the outline of concave section 51 when the orbiting scroll
member 27 is driven.
Moreover, this concave section 51 has a sectional shape
of a curved surface from the wall surface that forms the body
section 5A to the thrust receiving section 5C, and in
particular it is preferable that it be of a sectional shape of
a circular arc shape of radius R as shown in FIG. 3A. Since
the cylindrical wall surface that forms the body section 5A is
an inclined surface having a draft angle in which the diameter
of the wall surface gradually increases as it approaches the
opening section side from the thrust receiving section 5C, in
consideration of the cast drafting operation when casting, the
circular arc shaped concave section 51 of the radius R is
smoothly and continuously formed from this inclined surface.
It is preferable that such a concave section 51 be formed
using a casting surface that does not reguire machining
processing, and if the front housing 5 is a product of
aluminum alloy die casting, a smooth casting surface can be
directly used. Furthermore, the thrust receiving section 5C
of the front housing 5 is processed into a substantially plane
surface by machining processing, however, by providing a
smooth surface to the materials for the connection section of

the concave section 51 and the thrust receiving section 5C in
the casting step, burr processing after the .machining
processing can be omitted.
Moreover, since the concave section 51 is provided with a
circular arc shape of radius R, this circular arc can be
utilized in the corner section of the front housing 5 as a
curved surface for securing strength. Since such a curved
surface does not affect preservation of the gap section 5, it
is advantageous for reducing size.
Moreover, for the concave section 51, it is preferable
that the space that communicates with the suction port 45 and
the space of the narrow section in which the crankshaft 11 and
so forth are arranged be communicates with each other by
providing concave groove sections, which are communicating
passages 53, in the thrust receiving surface 5B in a radial
pattern. By providing these communicating passages 53, some
portion of the low temperature, low pressure refrigeration gas
introduced from the suction port 45 travels through the
communicating passages 53 to be supplied into the narrow space
section.
The scroll compressor constructed as described above
operates as described below.
When a rotation driving force is transmitted from an
external driving force source via a pulley and electromagnetic
clutch (not shown in the diagram) to the crankshaft 11 to

rotate the crankshaft 11, the orbiting scroll member 27
connected to the eccentric pin 11C of the crankshaft 11 via
the drive bush 19 and the drive bearing 21, is orbitally
driven around the stationary scroll member 2 5 while being
prevented from rotating by the rotation prevention mechanism
33. As a result, the refrigeration gas inside the intake
chamber 43 is sucked into the crescent shaped compression
chambers 29 formed in the two outermost places in the radial
direction. Since the scroll compression mechanism 23
comprising the orbiting scroll member 27 and the stationary
scroll member 25 generally has two suction ports in two
positions directly opposed to each other at approximately 180
degrees in this way, at this time, the spaces of the gap
section 5 formed between the inner surface of the body section
5A and the scroll compression mechanism 23, and the concave
section 51, serve as passages for guiding the refrigeration
gas from the suction port 4 5 to the compression mechanism
suction ports in two places, that is to say, for guiding the
refrigeration gas into the compression chambers 29.
After intake of the compression chamber 2 9 has been
closed at a predetermined rotational angle, the compression
chamber 29 shifts towards the center side while its capacity
is reduced. During this time, the refrigeration gas is
compressed, and when the compression chamber 29 has reached
the position that communicates with to the discharge port 25C,

the discharge reed valve 37 is pushed open and the compressed
gas is discharged into the discharge chamber 41, and it is
further discharged to outside of the scroll compressor 1
through the discharge chamber 41.
Thus, according to the present invention described above,
since a sectional area of the passage for gaseous fluid is
secured by forming the concave section 51 on the outside of
the thrust receiving surface 5B that supports the compression
mechanism, the diameter of the housing 3 can be reduced by-
reducing the dimensions of the gap section 5. Furthermore, in
the present invention, since the circular arc shaped concave
section 51 of radius R is provided, there is an advantage in
that the outer dimensions can be reduced compared to
conventional dimensions by the amount of the reduction in the
effect of interference between the housing 3 and the orbiting
scroll member 27 when the orbiting scroll member 27 is driven.
This point is described in detail with reference to
FIG. 3A showing the present invention, and FIG. 3B showing a
conventional example.
In the conventional example, the outer diameter of the
compressor has to be made large, since a gap of 5o is secured
so as not to interfere with the outermost section of the
orbiting scroll member 27 when it is driven, and a sidewall
base R is provided to avoid stress concentration on the
sidewall. Conversely, according to the present invention,

since the concave section 51 of radius R is provided, the δ0
gap is not required and the curved surface for securing
strength can be provided further on the inner side (center
side) within a range where it does not interfere with the
outermost end section of the orbiting scroll during the
driving operation. In this case, the draft angle of the
aluminum die cast housing 3 is necessary as with the
conventional example, however, since the rise of the sidewall
can be provided further towards the inside, a reduction in the
outer diameter of the compressor can be achieved.
Moreover, by providing a deeper concave section 51 in the
present invention, the capacity of the housing interior can be
further increased while securing the outer diameter of the
housing. In this case, a muffler effect is achieved by which
it becomes possible to reduce pulsation generated by the
compressor, and this in turn may contribute to a reduction in
vibration and noise. Here, by providing the concave section
51 on the outside of the thrust receiving surface 5B, an
increase in the axial direction dimension of the scroll
compressor 1 becomes a concern. However, since there are
generally existing components in the vicinity of the position
on the thrust receiving surface 5B in which the concave
section is provided, in actuality there is r.ot an axial
direction increase in the scroll compressor 1.
Furthermore, a technique of providing a. separate anti-

wear plate between the thrust receiving section 5C and the
orbiting scroll member 27 of the scroll compressor 1 is
commonly known. Of course, even in this kind of case, the
invention of the present application enables effects similar
to that described above.
Moreover, the aforementioned embodiment was described
with the example of the scroll compressor 1, however, the
present invention is not limited to this. The present
invention can be universally applied to other forms of
compressors such as a rotary compressor, a screw compressor,
and an in-line piston pump compressor, and also to fluid
machines other than compressors such as a similar kind of pump
for handing fluid.
[Second embodiment]
Hereinafter, a second embodiment of the present invention
is described, with reference to FIG. 4 and FIG. 5. A scroll
compressor 101 according to the present embodiment is used for
compression of refrigeration gas (fluid) of an air
conditioning apparatus for example.
FIG. 4 is a sectional view for explaining a construction
of the scroll compressor 101 according to the present
embodiment. FIG. 5 is a cutaway sectional view showing one
part of a large diameter shaft section.
The scroll compressor 101 is provided with a housing 103,
a scroll compression mechanism (compression mechanism) 105, a

rotation prevention section 107, and a crankshaft 109.
The housing 103 is a hermetic container within which the
scroll compression mechanism 105 and so forth are arranged as
shown in FIG. 4.
The housing 103 is provided with a rear case 111 that
constitutes a rear section (upper side in FIG. 4) and a front
case 113 that constitutes a front section (lower section in
FIG. 4) .
The rear case 111 is hollow and has a substantially dome
shape, and it is formed by means of aluminum alloy casting.
The front case 113 has a joint shape of a hollow cylinder
and a circular cone, and is formed by means of aluminum alloy
casting.
The rear case 111 and the front case 113 are joined by
being fastened by bolts 115, and an enclosed space M (intake
space) is formed therein.
The scroll compression mechanism 105 is provided with a
stationary scroll 117 and an orbiting scroll 119.
The stationary scroll 117 is provided with a stationary
end plate 121 and a spiral shaped stationary spiral body
(spiral wrap) 123 standing upright on the front face of the
stationary end plate 121.
On the rear side of the stationary end plate 121 is
formed a concave section 125 recessed towards the front side
in the center section, and a rear end surface 127 that

surrounds the circumference of the concave section 125 in a
ring shape.
The rear end surface 127 is abutted against an end
surface 12 9 provided in a ring shape on the front of the rear
case 111, and the stationary scroll 117 is fixed and attached
to the rear case 111 by fastening at a plurality of places by
bolts 131.
At this time, since the rear case 111 and the stationary
scroll 117 are sealed off from the enclosed space M by a seal
133 such as an O-ring, a hollow section of the rear case 111
and the concave section 125 of the stationary end plate 121
form a discharge chamber 135.
A discharge port 137 for compressed fluid is formed in a
substantially center section of the concave section 125 of the
stationary end plate 121. This discharge port 137 is opened
and closed by a discharge valve (not shown in the diagram)
that is attached to the rear surface of the stationary end
plate 121, and which discharges compressed fluid into the
discharge chamber 135.
An intake boss section 139 is provided on a front end
section of a cylindrical section of the front case 113.
A suction port section 141 that communicates with the
enclosed space M and introduces refrigeration gas (fluid) from
outside into the enclosed space M, is cut out in the intake
boss section 139.

The orbiting scroll 119 is provided with an orbiting end
plate 143 and a spiral shaped orbiting spiral body (spiral
wrap) 145 standing upright on the rear surface of this
orbiting end plate 143.
The orbiting scroll 119 is provided in such a way that
the orbiting spiral body 145 meshes with the stationary spiral
body 123.
The stationary scroll 117 and the orbiting scroll 119
mesh with each other so as to be eccentric to each other by a
predetermined distance, while having a 180 degree phase
difference. As a result, compression chambers P, which are
enclosed spaces, are formed in a plurality of point-symmetric
positions with respect to the centers of the stationary spiral
body 123 and the orbiting spiral body 145.
A cylindrical hollow orbiting boss 147 is provided on the
front surface center of the orbiting end plate 143 (the left
side in FIG. 4 (crankshaft 109 side)) so as to project
forward.
The orbiting scroll 119 is supported on the front case
113 so that it can orbit around the stationary scroll 117.
The rotation prevention section 107 is provided with a
plurality of rings 149 and a plurality of pins 151.
The respective rings 149 are pressed fitted, or fitted so
as to allow some play, (inserted with play) into a plurality
of ring holes 153 provided at substantially equal intervals on

the outer circumference side of the front side end surface of
the orbiting end plate 143 on a circumference of a
predetermined radius from the center of the orbiting scroll
119.
The numbers of the pins 151 and the rings 149 provided
are equal, and the respective pins 151 are inserted and fitted
into a rear side end surface of the circular cone base section
of the front case 113 so as to project into the corresponding
rings 149.
By inserting the pins 151 into the rings 149 so as to
allow play (inserting with play), the orbiting scroll 119 fits
with the front case 113 so that rotation of the orbiting
scroll 119 is prevented when it orbits. At this time, the pin
151 revolves along an inner circumferential surface of the
ring 149 in a direction the same as the orbiting direction of
the orbiting scroll 119.
For example, a commonly known Oldham ring may be used as
the rotation prevention section 107.
The crankshaft 109 is arranged so as to extend from the
front side to the rear side, and an outer circumferential
surface 157 of a large diameter shaft section 155 provided on
the rear side thereof is rotatably supported on the front case
113 via a large diameter shaft section needle bearing 159
(needle shaped roller bearing having an outer ring).
The large diameter shaft section needle bearing 159 is

constructed, as shown in FIG. 5, from an outer ring 161, a
cage 163, and a plurality of needle shaped rollers 165.
The outer ring 161 is of a substantially hollow
cylindrical shape, and a rear collar section 167 and a front
collar section 169 that respectively bend inwards at right
angles are formed on both end sections in an axial direction J
of the crankshaft 109.
The cage 163 is attached on the inside of the outer ring
161, holding the plurality of needle shaped rollers 165 at
substantially equal intervals in the circumferential
direction.
The large diameter shaft section needle bearing 159 is
held by being tightly fitted into a concave section 171
provided in a substantially middle section in the axial
direction J of the circular cone section of the front case
113.
Small chamfers are provided on both of the end sections
of the large diameter shaft section 155 in the axial direction
J. The portion inside of these chamfers (portion positioned
between these chamfers) comprises the outer circumferential
surface 157.
A rear end position A (end section position on one end
side) of the outer circumferential surface 157 is positioned
further to the front side (other end side) than a tip end
position C (end section position of one end side) of the rear

collar section 167.
Also, a front end position B (end section position on the
other end side) of the outer circumferential surface 157 is
positioned further to the rear side (one end side) than a tip
end position D (end section position of the other end side) of
the front collar section 169.
Furthermore, as shown in FIG. 6, the length L1 of the
outer circumferential surface 157 in the axial direction J is
made shorter than length L2 of the outer ring 161 in the axial
direction J.
Since the intermediate positions of the outer
circumferential surface 157 and the outer ring 161 in the
axial direction J are substantially aligned, the
aforementioned gaps are respectively provided in the front and
rear of the outer circumferential surface 157.
A gap between the front end position B of the outer
circumferential surface 157 and the tip end position D of the
front collar section 169 is provided for lubricating a lip
seal 175 (refer to FIG. 4). Accordingly, in the case where
the need for lubrication of the lip seal 175 is obviated by
providing a separate lubrication means, this gap may not need
to be provided.
The length L1 of the outer circumferential surface 157 in
the axial direction J is formed to be longer than the length
of the needle shaped roller 165 so that the load applied on

the needle shaped roller 165 will not be biased.
As shown in FIG. 4, a front end of the crankshaft 109
projects ahead of the front case 113, and is rotatably
attached to the front case 113 by a ball bearing 173 provided
in the front end section of the front case 113.
On the side of the crankshaft 109 to the rear of the ball
bearing 173, the enclosed space M is sealed off from outside
by the lip seal (seal member) 175 formed from a mechanical
seal.
The front end section of the crankshaft 109 projecting
from the front case 113 is constructed so as to be rotated by
a driving device such as an engine or a motor (not shown in
the diagram).
A crank chamber 181 into which the orbiting boss 147 is
inserted with some clearance is provided in the center section
of the rear side of the circular cone section of the front
case 113.
The rear side end sections of the large diameter needle
bearing 159 and the large diameter shaft section 155 face the
crank chamber 181.
An eccentric shaft (eccentric member) 183, the axial
center of which is eccentric, is provided on the rear side of
the large diameter shaft section 155 of the crankshaft 109 so
as to be positioned within a hollow section of the orbiting
boss 147.

A counter weight 185 is provided around the eccentric
shaft 183. The counter weight 185 covers the eccentric shaft
183 and is arranged within the crank chamber 181 so that its
front end section extends in a direction (right direction in
FIG. 4) opposite to the eccentric direction (left direction in
FIG. 4) of the eccentric shaft 183, and is fixed on and
attached to the large diameter shaft section 155.
An eccentric bush 187 surrounds the circumference of the
cylindrical counter weight 185 that is positioned within the
orbiting boss 147, and is freely rotatably fitted within the
hollow section of the orbiting boss 147 via the needle
bearings 189.
The axial center of the eccentric bush 187 is eccentric
with respect to the axial center of the crankshaft 109.
The eccentric bush 187 transmits the rotational driving
force of the crankshaft 109 to the orbiting scroll 119 to
perform the function of orbitally driving the orbiting scroll
119.
The compression operation of the scroll compressor 101
constructed as described above is described.
Rotational driving force from an engine or a motor (not
shown in the diagram) is transmitted to the crankshaft 109,
and this rotational driving force is transmitted to the
orbiting scroll 119 of the scroll compression mechanism 105
via the eccentric shaft 183, the counter weight 185, the

eccentric bush 187, and the orbiting boss 14 7.
The orbiting scroll 119, rotation of which is prevented
by the rotation prevention section 107, is driven so as to
revolve around a circular orbit with a radius of the orbiting
radius.
When the orbiting scroll 119 is orbitally driven,
refrigeration gas enters the enclosed space M of the housing
103 via the suction port section 141 and it is sucked into a
compression chamber P of the scroll compression mechanism 105.
At this time, since lubrication oil contained in the
refrigeration gas is introduced into the compression chamber P
together with the refrigeration gas, the scroll compression
mechanism 105 is lubricated.
As the capacity of the compression chamber P is reduced
by the orbital motion of the orbiting scroll 119, the
refrigeration gas reaches the compression chamber P of the
center section while it is being compressed.
The compressed refrigeration gas that reaches the
compression chamber P of the center section is discharged from
the discharge port 137 to the discharge chamber 135.
The compressed refrigeration gas that has been discharged
into the discharge chamber 135 is supplied to a radiator
through a discharge hole (not shown in the diagram),
At this time, the counter weight 185 is rotated by the
eccentric shaft 183 of the crankshaft 109 in a phase shifted

substantially 180 degrees from the orbital motion of the
orbiting scroll 119. Therefore, the counter weight 185
cancels out the centrifugal force that acts on the orbiting
scroll 119, and unbalance of the dynamic mass around the
crankshaft 109 is reduced.
Moreover, since the counter weight 185 rotates whereas
the orbiting scroll 119 revolves, a tip end of the counter
weight 185 arranged within the crank chamber 181 rotates
relatively inside the crank chamber 181.
Next, the lubrication operation related, to the crankshaft
109 is described.
The low temperature and low pressure refrigeration gas
that has been sucked into the enclosed space M flows into the
crank chamber 181 that forms the enclosed space M.
The refrigeration gas, which contains lubrication oil and
which has flowed into the crank chamber 181, travels through
the gap between the rear end position A of the outer
circumferential surface 157 and the tip end position C of the
rear collar section 167, and is introduced into the large
diameter shaft section needle bearing 159.
Since the large diameter shaft section needle bearing 159
is cooled and lubricated by this refrigeration gas and
lubrication oil, the temperature within the enclosed space M
becomes uniform and lubricating properties can be improved.
The refrigeration gas introduced into the large diameter

shaft section needle bearing 159 travels through the gap
between the front end position B of the outer circumferential
surface 157 and the tip end position D of the front collar
section 169 and reaches the lip seal 175, and it cools and
lubricates the lip seal 175.
Thus, since a gap for introducing the refrigeration gas
to the large diameter shaft section needle bearing 159 is
secured by positioning the rear end position A of the outer
circumferential surface of the large diameter shaft section
155 to the front side of the tip end position C of the rear
collar section 167, and since a gap for introducing the
refrigeration gas to the lip seal 175 is secured by
positioning the front end position B of the outer
circumferential surface 157 to the rear side of the tip end
position D of the front collar section 169, a generic needle
bearing can be employed for the large diameter shaft section
needle bearing 159 resulting in a reduction in production
cost.
Meanwhile, the refrigerant introduced into the crank
chamber 181 is introduced into the needle bearing 189 to be
used for cooling and lubricating the needle bearing 189 and s
forth.
Moreover, since the large diameter shaft section needle
bearing 159 is used, the size of the front case 113 does not
need to be increased, and a reduction in size and weight of

the housing can be achieved.
In the present embodiment, small chamfers are provided on
the front and rear ends of the large diameter shaft section
155. However, cutaway sections 177 that continue in the
circumferential direction and have large rectangular shaped
sections as shown in FIG. 7, or cutaway sections 177 having
large triangular shape sections as shown in FIG. 8 may be
provided.
Moreover, the shape of the section of the cutaway section
177 is not limited to these, and it may be an arbitrary shape.
Furthermore, it may be discontinuous in the circumferential
direction.
In this way, the length of the large diameter shaft
section 155 in the axial direction J can be made greater while
securing the gap between the outer ring 161 of the large
diameter shaft section needle bearing 159 and the shaft
section 155.
[Third embodiment]
Hereinafter, a third embodiment of the present invention
is described, with reference to FIG. 9 through FIG. 11.
FIG. 9 is a longitudinal sectional view showing a scroll
compressor 201 according to a third embodiment of the present
invention.
The scroll compressor 201 has a housing 203 that
constructs an outline thereof. This housing 203 is constructed

by integrally fastening and fixing a front housing 205 and a
rear housing 207 by bolts 209 (second bolts). Flanges 205A
and 207A for fastening are integrally formed at equal
intervals in a plurality of places, for example in four
places, on each of the circumferences of the front housing 205
and the rear housing 207. By fastening these flanges 205A and
207A to one another using the bolts 209, the front housing 205
and the rear housing 207 are integrally joined.
A crankshaft 211 is supported within the front housing
205 via a main bearing 213 and a sub bearing 215, allowing it
to rotate freely around the axis L. One end side (left side
in the diagram) of the crankshaft 211 is a small diameter
shaft section 211A. This small diameter shaft section 211A
passes through the front housing 205 and projects to the left
side in FIG. 9. As is commonly known, an electromagnetic
clutch, a pulley and so forth (not shown in the diagram) that
receive power, are provided on the projecting section of the
small diameter shaft section 211A, and power is transmitted
thereto via a V belt from a driving force source (not shown in
the diagram) such as an engine.
Furthermore, a mechanical seal (lip seal) 217 is
installed between the main bearing 213 and the sub bearing 215
to air tightly seal between inside the housing 203 and the
atmospheric air.
A large diameter shaft section 211B is provided on the

other end side (right side in FIG. 9) of the crankshaft 211.
Furthermore, an eccentric pin 211C, which is eccentric to the
axis L of the crankshaft 211 by a predetermined distance, is
provided integrally on the large diameter shaft section 211B.
This large diameter shaft section 211B and the small diameter
shaft section 211A are respectively supported within the front
housing 205 to allow free rotation, through the main bearing
213 and the sub bearing 215. An orbiting scroll member 227
described later is connected to the eccentric pin 211C via a
drive bush 219 and a drive bearing 221. Therefore, by
rotating the crankshaft 211, the orbiting scroll member 227 is
orbitally driven.
A balance weight 219A for canceling an unbalanced load
occurring as a result of the orbiting scroll member 227 being
orbitally driven, is formed integrally on the drive bush 219.
This balance weight 219A orbits together with orbital drive of
the orbiting scroll member 227.
A pair of a stationary scroll member 225 and the orbiting
scroll member 227 that constitute a scroll compression
mechanism 223, is fitted into the interior of the housing 203.
The stationary scroll member 225 is constructed from an end
plate 225A and a spiral wrap 225B standing upright on the end
plate 225A. Meanwhile, the orbiting scroll member 227 is
constructed from an end plate 227A and a spiral wrap 227B
standing upright on the end plate 227A.

In the stationary scroll member 225 and the orbiting
scroll member 227, as shown in FIG. 10A and FIG. 10B, step
sections 225E, 225F and 227E, 227F are provided respectively
on the tip end surfaces 225C, 227C and the bottom surfaces
225D, 227D of the spiral wraps 225B, 227B in predetermined
positions along their spiral direction. Taking these step
sections 225E, 225F and 227E, 227F as boundaries, in the wrap
tip end surfaces 225C and 227C, tip end surfaces 225G and 227G
on the outer circumference side are higher in the axis L
direction and tip end surfaces 225G and 227E on the inner
circumference side are lower. Moreover, in the bottom
surfaces 225D and 227D, bottom surfaces 225C and 2271 on the
outer circumference side are lower in the axis L direction and
bottom surfaces 225J and 227J on the inner circumference side
are higher. As a result, the heights of the spiral wraps 225B
and 227B on the outer circumference side are higher than those
of the wraps on the inner circumference side.
The above pair of the stationary scroll member 225 and
the orbiting scroll member 227 are meshed together in a state
where each of their centers is distanced from the other by the
orbital radius amount, and where the spiral wraps 25B and 27B
are meshed v/ith each other with a 180 degree phase shift. As
a result, as shown in FIG. 9, a pair of compression chambers
229 limited by the end plates 225A, 227A and the spiral wraps
225B, 227B are formed between both of the scroll numbers 225

and 227 in symmetry with respect to the center of the scroll.
The height of the compression chamber 229 in the axis L
direction on the outer circumference side of the spiral wraps
225B and 227B is higher than that on the inner circumference
side. As a result, a compression mechanism that enables three
dimensional compression capable of compression in the
circumferential direction and in the wrap height direction is
attained.
The stationary scroll member 225 is fixed and installed
on the inner surface of the rear housing 207 using bolts 231
(first bolts) . The orbiting scroll member 227 is orbitally
driven by the eccentric pin 211C connected as described above
via the drive bush 219 and the drive bearing 221 to the boss
section provided on the back surface of the end plate 227A.
The back surface of the end plate 227A of the orbiting
scroll member 227 is supported on a thrust receiving surface
205B formed in the front housing 205. The orbiting scroll
member 227 is prevented from rotating by a rotation prevention
mechanism 233, such as a pin ring or an Oldham ring, that
intervenes between this thrust receiving surface 205B and the
end plate 227A, so as to be orbitally driven around the
stationary scroll member 225.
An opening of a discharge port 225K for discharging
compressed refrigeration gas, is provided in the center
section of the end plate 225A of the stationary scroll member

225. In this discharge port 225K, a discharge reed valve 237
is attached to the end plate 225A via a retainer 235.
Furthermore, a seal member 239 (first seal member) such as an
O-ring is placed on the back surface side of the end plate
225A of the stationary scroll member 225 to make tight contact
with the inner surface of the rear housing 207. As a result,
a discharge chamber 241 that is separate from the inner space
of the housing 203 is formed between the end plate 225A and
the rear housing 207. Accordingly, the inner space of the
housing 203 apart from the discharge chamber 241 is
constructed to function as an intake chamber 243.
Refrigeration gas returning from a refrigeration cycle via a
suction port 245 provided in the front housing 205 is sucked
into the intake chamber 243, and the refrigeration gas is
sucked into the compression chamber 229 via this intake
chamber 243. Moreover, a seal member 247 such as an O-ring
(second seal member) is placed on a joint surface between the
front housing 205 and the rear housing 207 to air tightly seal
the intake chamber 243 formed within the housing 203 from the
atmospheric air.
Here, as shown in FIG. 9, the front housing 205 is
provided with: a large diameter body section 205C that houses
the scroll compression mechanism 225; a thrust receiving
section 205D that continues from the body section 205C and has
its diameter reduced in the radial direction (it extends from

the end section of the body section 205C towards the inner
circumference side), for forming the aforementioned thrust
receiving surface 205B; a medium diameter crankshaft support
section 205F that continues from the thrust receiving section
205D and has its diameter further reduced, for forming a
bearing housing section 205E to house the main bearing 213;
and a small diameter boss section 205G that continues from the
crankshaft support section 205F, for installing the sub
bearing 215 and mechanical seal 217. That is to say, the
front housing 205 is formed so as to form a funnel shaft, the
diameter of which is reduced in steps.
On the other hand, as shown in FIG. 11, the rear housing
207 is formed in a dish shape, and is provided with: a concave
section 207B for forming the discharge chamber 241; a spigot
section 207C that fits with an opening end of the body section
205C of the front housing 205; and an fitting section 207D
with which a spigot section 225L provided on the back surface
of the end plate 225A of the stationary scroll member 225
fits. The fitting section 207D is formed on the outer
circumference side of the position where the bolts 231 are
fastened.
The spigot section 207 has a substantially cylindrical
shape. The above seal member 247 is placed on the outer
circumferential surface of the spigot section 207C. Moreover,
on the outer circumferential surface of the spigot section

207C, on the mouth side (tip end side) of the installation
section of the seal member 247, as shown in FIG.11, a minute
gap S is formed between the spigot section 207C and the large
diameter opening section in the body section 205C of the front
housing 205. Specifically, in an area on the mouth side of
the installation section of the seal member 247, the outer
diameter of the spigot section 207 is smaller than the inner
diameter of the opening section of the front housing 205, and
the minute gap S is thereby formed between the spigot section
207 and the opening section of the housing 205. Since the
minute gap S is extremely small in size, only the place where
the minute gap S is formed is denoted in FIG. 11 by reference
symbol S. In a state where this spigot section 207C has been
fitted to the opening of the body section 205C in the front
housing 205, the housing 205 and 207 are both joined via the
seal member 247 to air tightly seal off the interior of the
housing from the atmospheric air, by fastening and fixing the
flanges 205A and 207A of the both housings 205 and 207 to each
other by the bolts 209.
Moreover, as shown in FIG. 11, the spigot section 225L of
the stationary scroll member 225 is fitted with the fitting
section 207D of the rear housing 7. In a state where the
above seal member 239 is placed in a corner section formed
between this fitting section 207D and the spigot section 225L,
the stationary scroll member 225 is fastened and fixed on the

inner surface of the rear housing 207 by the bolts 231 via a
screw boss section 225N formed in a ring shape on the end
surface of the stationary scroll member 225. The corner
section here in the spigot section 207C refers to an
intersection section of an outer circumferential surface and a
wall surface that stands up to the outer circumference side
from this outer circumferential surface, while the corner
section in the fitting section 207D refers to an intersection
section of an inner circumferential surface and a wall surface
that stands up towards the outer circumference side from this
inner circumferential surface. Then, as a result of employing
such construction, since a high pressure load is not applied
to an end plate outermost circumference portion 225M on the
outer circumference side of the spigot section 225L of the end
plate 225A, the thickness of the end plate outermost
circumference portion 225M is made substantially less than or
equal to half of the thickness of other portions of the end
plate around the entire circumference.
According to the construction described above, the rear
housing 207 and the stationary scroll member 225 are fixed and
installed in the state where the stationary scroll member 225
is positioned with respect to the rear housing 207 by fitting
the fitting section 207D with the spigot section 225L,
regardless of the placement of the seal member 239. Moreover,
in the above fitting sections, the interior of the housing 203

is separated into the high pressure discharge chamber 241 and
the low pressure intake chamber 243 and they are sealed off
from each other by the seal member 239 placed in the corner
section formed between the fitting section 207D and the spigot
section 225L as described above. Furthermore, on the outer
circumference side of the seal member 239 that separates the
discharge chamber 241 and the intake chamber 243 from each
other, as described above, the seal member 247 placed between
one end opening of the body section 205 in the front housing
205 and the spigot section 207C of the rear housing 207 air
tightly separates, the intake chamber, that is, the interior
of the housing 203, from the atmospheric air.
Next, the operation of the scroll compressor according to
the present embodiment is described.
When a rotation driving force is transmitted from an
external driving force source via a pulley and electromagnetic
clutch (not shown in the diagram) to the crankshaft 211 to
rotate the crankshaft 211, the orbiting scroll member 227
connected to the eccentric pin 211C of the crankshaft 211 via
the drive bush 219 and the drive bearing 221 is orbitally
driven around the stationary scroll member 225 while being
prevented from rotating by the rotation prevention mechanism
233.
Refrigeration gas in the intake chamber 243 is sucked
into the compression chamber 229 formed on the outermost side

in the radial direction by this orbital driving of the
orbiting scroll member 227. After intake of the compression
chamber 229 has been closed at a predetermined rotational
angle, the compression chamber 29 shifts towards the center
side as its capacity in the circumferential direction and in
the wrap height direction is reduced. The refrigeration gas
is compressed during this time, and when it has reached the
position where the compression chamber communicates with the
discharge port 225K, the discharge reed valvs 237 is pushed
open, and the compressed gas is discharged into the discharge
chamber 241. This compressed refrigeration gas is discharged
to outside the compressor through the discharge chamber 241.
The pressure force of the high pressure compressed gas
discharged into the discharge chamber 241 is loaded onto the
end plate 225A of the stationary scroll member 225 and the
rear housing 207 that constitute the discharge chamber 241 on
the inner circumference side of the seal member 239 that
separates the discharge chamber 241. The seal member 239 is
placed between the end surface of the end plate 225A and the
inner surface of the rear housing 207 in a position on the
inner circumference side of the outer circumferential surface
of the end plate 225A. Thus, an area on the end plate 225A
and the rear housing 207 on which excessive pressure load is
applied can be reduced by the amount to which the seal member
239 is positioned on the inner circumference side of the end

plate 225A. As a result, pressure deformation due to
excessive pressure load on the end plate 225A and the rear
housing 207 can be made very small.
Moreover, an excessive pressure load is no longer applied
on the end plate outermost circumference portion 225M, which
has a thinner end plate thickness on the outer circumference
side of the spigot section 225L of the end plate 225A on which
the seal member 239 is installed. As a result, even if the
thickness of the end plate outermost circumference portion
225M is made thinner than the other portions, there is no
possibility of pressure deformation due to high pressure, and :
compression performance is not affected.
Moreover, even if a failure occurs in the seal member
239, or a minute deformation occurs in the end plate 225A or
the rear housing 207 due to an unusual rise in high pressure
resulting in leakage of high pressure compressed gas, the
discharge chamber 241 does not come into direct contact with
the atmospheric air, and the compressed gas is leaked into the
intake chamber 243 formed on the outer circumference side of
the discharge chamber 241. Therefore, direct leakage of the
compressed gas from the discharge chamber 241 into atmospheric
air can be avoided.
As a result, according to the present embodiment, the
following effects can be attained.
Since the seal member 239 that separates the discharge

chamber 241 is placed in the position on the inner
circumference side of the outer circumferential surface of the
end plate 225A of the stationary scroll member 225, the area
of the surface on the end plate 225A and the rear housing 207
on which pressure load due to high pressure is loaded can be
reduced. Accordingly, stress on the end plate 225A, the rear
housing 207, and the bolts 231 can be slightly reduced.
Therefore, the thickness of these parts can be reduced, and a
reduction in weight and production cost of the scroll
compressor 201 can thereby be achieved.
Moreover, since the intake chamber 243 is formed on the
outer circumference side of the seal member 239 that separates
the discharge chamber 241, even if gas leaks from the
discharge chamber 241, direct leakage of the gas into
atmospheric air can be prevented. Furthermore, in the case of
an unusual rise in pressure, damage to the compressor due to
the unusual rise in pressure can be prevented before it occurs
by leaking compressed gas from the discharge chamber 241 into
the intake chamber 243. Incidentally, even if high pressure
gas has leaked from the discharge chamber 241 into the intake
chamber 243, this does not cause a problem in particular.
Moreover, since the seal member 247 that seals off the
intake chamber 243 from the atmospheric air is placed on the
outer circumference side of the seal member 239, the seal
member 247 need only be able to seal a portion where there is

a low pressure difference between low pressure and the
atmospheric air, and a seal member that is somewhat less
functional and of lower cost compared to the seal member 239
may be employed. Furthermore, since the front housing 205 and
the rear housing 207 can be fastened and fixed in the portion
where the pressure difference is small, the bolts 209 and the
flanges 205A and 207A for fastening can be made small.
Therefore, this also contributes to achieving a reduction in
weight and production cost.
Moreover, since the spigot section 207C provided in the
rear housing 207 is fitted into the opening section of the
body section 205C of the front housing 205 to join the both
housings 205 and 207, pressure deformation of the rear housing
207 in the opening direction can be suppressed by the front
housing 205. Therefore, minute pressure deformation in the
rear housing 207 can be further suppressed, and gas leakage
due to pressure deformation can be minimized to a greater
extent. Furthermore, since the seal member 247 is placed in
the spigot section 207C, the seal member 247 shifts in the
axial direction with respect to pressure deformation in the
opening direction of the rear housing 207. therefore, the
sealing property is not compromised and a seal can be reliably
secured. This also contributes to the prevention of gas
leakage. Furthermore, since the seal member 247 is installed
on the spigot section 207C side, it becomes easier to hold the

seal member 247, and since the minute gap S is formed between
the spigot section 207C and the opening of the front housing
205, a difference between the outer diameter of the spigot
section 207C and the inner diameter of the seal member 247 on
the mouth side of the installation section of the seal member
247 of the spigot section 207C is smaller, and installation of
the seal member 247 in the spigot section 207C becomes easier
as a result. Moreover, on the mouth side of the installation
section of the seal member of the spigot section 207C, a
clearance for allowing relative movement between the spigot
section 207C and the front housing 205 is secured between the
spigot section 207C and the opening section of the front
housing 205, and fitting the spigot section 207C to the
opening section of the front housing 205 can be carried out
more easily. Therefore, assembly of the scroll comp3:essor can
be made easier.
Moreover, since the stationary scroll member 225 is fixed
and installed by fitting the spigot section 225L of the
stationary scroll member 225 with the fitting section 207D of
the rear housing 207 and placing the seal member 239 on the
outer circumference side of the stationary scroll member 225,
it can be accurately positioned with respect to the rear
housing during assembly regardless of the mounting of the seal
member 239.
Moreover, since the seal member 239 is placed in the

corner section between the spigot section 225L and the fitting
section 207D, processing a seal groove for installing the seal
member 239 is not required, and processing cost can be reduced
as a result.
Furthermore, since excessive load due to high pressure is
no longer loaded on the outermost circumference portion 225M
of the end plate 225A in the stationary scroll member 225, the
thickness of the end plate outermost circumference portion
225M can be made thinner than that of other portions.
Therefore, the weight of the stationary scroll member 225 can
be reduced, leading to a reduction in the weight of the scroll
compressor 201. In particular, since the above portion 225M
is an outermost circumference section of the end plate 225A,
by making the plate thickness thinner around the entire
circumference, the volume of material can be reduced by an
amount that corresponds to that area. Therefore, a reasonable
reduction in weight and volume of material to be used can be
achieved, and a reduction in the weight and cost of the scroll
compressor can be expected.
Moreover, in the present embodiment, the scroll
compression mechanism 223 is of a construction in which the
height of the spiral wrap on the outer circumference side of
the spiral wraps 225B and 227B is higher than that on the
inner circumference side, so that three dimensional
compression allowing compression in the circumferential

direction and in the wrap height direction can be achieved.
As a result, in the scroll compressor according to the present
embodiment, capacity can be increased without increasing the
outer diameter of the scroll. This also contributes to
achieving a reduction in size and weight of the scroll
compressor.
[Fourth embodiment]
Next, a fourth embodiment of the present invention is
described, with reference to FIG. 12.
The present embodiment is characterized by a fixed-
installation structure of the stationary scroll member 225
with respect to the rear housing 207. Other characteristics
of the present embodiment are similar to those of the third
embodiment, and descriptions thereof are therefore omitted.
FIG. 12 is a sectional view showing a portion in which a
stationary scroll member 225 is fastened and fixed on a rear
housing 207 by bolts 231.
In the present embodiment, on the back surface side of an
end plate 225A of the stationary scroll member 225, a screw
boss section 225N is provided in a position that is on the
inner circumference side of a step section 225F provided on a
bottom surface 225D, and that is also on the inner
circumference side of the spigot section 225L on which the
seal member 239A that separates the discharge chamber 241 is
installed. The screw boss section 225N is provided in a ring

shape so as to project from the end surface of the end plate
along the axis L direction towards the side opposite to the
spiral wrap 225B (right side in FIG. 12) .
Screw holes 225P for the fastening bolts 231 are made in
this screw boss section 225N in three to four places at
appropriate intervals in the circumferential direction. The
screw holes 225P are provided in the screw boss section 225N
so as to extend by a length T with respect to a bottom surface
2271 on the outer circumference side of the step section 225F
towards the wrap side in the axial direction. That i.s to say,
taking advantage of the bottom surface 227J on the inner
circumference side of the step section 225F being higher than
the bottom surface 2271 on the outer circumference side in the
axial direction L, the screw hole 225P, the length of which is
required to be at least 1.5 times the screw diameter, is
provided in this part so as to extend by the above length T.
In the present embodiment, instead of the seal member 239
installed in the corner section of the spigot section 225L in
the third embodiment, a seal groove 225Q is provided on the
end surface on the outer circumference side of the spigot
section 225L of the end plate 225A, and a seal member 239A
such as an O-ring is installed therein.
This seal member 239A may be provided on the end surface
on the outer circumference side of the screw hole 225P in the
screw boss section 225N. As a result, the area of the part on

which pressure load due to high pressure is applied can be
made still smaller.
According to the present embodiment, the following
effects can be attained by the construction described above.
In the present embodiment, the screw boss section 225N is
formed in a part where the thickness of the end plate 225A is
made thick by providing the step section 225F, and making use
of the thickness of the screw boss section 225N, the screw
hole 225P for the bolt 231, the engagement depth of which
needs to be at least 1.5 times the screw diameter, is provided
in this screw boss section 225N. As a result, the length of
the screw boss section 225N in the axis L direction does not
have to be particularly increased for providing the screw
holes 225P of the required dimensions. Accordingly,, the
length of the scroll compressor 201 in the axial direction L,
the minimum dimension being restricted to the length of the
first bolts 231 can be shortened. Therefore, in the present
embodiment, a reduction in size and weight of the scroll
compressor 201 can be realized, improving the mountability of
the scroll compressor 201.
In the present embodiment, in particular, the screw hole
225P is provided so as to extend, by the length T, from the
bottom surface 2251 on the outer circumference side of the
step section 225F to the wrap side in the axial direction.
Therefore, the length of the scroll compressor 201 in the

axial direction, the minimum dimension being restricted to the
length of the first bolts 231 can be shortened by at least the
length T or greater. As a result, in the present embodiment,
an effect of a reduction in size and weight of the scroll
compressor 201 can be enhanced to the greatest possible
extent.
Moreover, in the present embodiment, the screw boss
section 225N is provided on the inner circumference side of
the seal member 239A, and the stationary scioll member 225 is
fastened and fixed in the position by the bolts 231. As a
result, the force loaded on the seal member 239A can be
reduced. Therefore, in the present embodiment, the lifetime
of the seal member 239A can be extended.
[Fifth embodiment]
Next, a fifth embodiment of the present invention is
described, with reference to FIG. 13.
The present embodiment differs from the third and the
fourth embodiments described above in that a clamping groove
225R for use during processing is provided in the stationary
scroll member 225. Other characteristics of the present
embodiment are similar to those of the third and the fourth
embodiments, and descriptions thereof are therefore omitted.
FIG. 13 is a partial sectional view showing one part of
the stationary scroll member 225.
In the present embodiment, a groove 225R for clamping the

stationary scroll member 225 using a chuck when processing is
provided on the outer circumference portion of the screw boss
section 225N of the stationary scroll member 225. This groove
225R may be provided in a required range to suit the chuck or
it may be provided around the entire circumference of the
screw boss section 225N.
The stationary scroll member 225 is generally made by
machining a wrap surface of the spiral wrap 225B by end
milling. At this time, the outer circumferential surface of
the end plate 225A is clamped by a chuck while being
processed. However, as described in the aforementioned third
and the fourth embodiments, if the thickness of the outermost
circumference portion 225M of the end plate 225A in the
stationary scroll member 225 is made too thin, then distortion
may occur during clamping, and this could affect processing
accuracy.
As shown in the present embodiment, the stationary scroll
member 225 can be stably fixed when processing by piroviding
the groove 225R for clamping in the screw boss section 225N
that is the part in the stationary scroll member 225 where the
plate thickness of the end plate 225A is thickest and the
rigidity of the end plate 225A is high, and clamping the
stationary scroll member 225 in this groove 225R while
processing it. Therefore, the stationary scroll member 225
can be processed at a high level of accuracy.

Furthermore, by providing the groove 225R around the
entire circumference of the screw boss section 225N, a
reduction in weight of the stationary scroll member 225 for
the weight corresponding to the volume of this groove 225R can
be achieved, and a reduction in the weight of the stationary
scroll member can be realized as a result.
In the third, the fourth and fifth embodiments described
above, a scroll compressor provided with a compression
mechanism capable of performing three dimensional corapression,
that is, compression in the circumferential direction and in
the wrap height direction has been described. However, the
present invention is not limited to this, and the invention
according to the third and the fifth embodiments may be
applied to a normal scroll compressor that is not provided
with a step section in the wrap height direction and that can
perform compression only in the circumferential direction.

We claim:
1. A fluid machine (1) in which a compression mechanism (23)
is housed and installed within a funnel shaped housing (3), a
compression mechanism main body (25, 27) of said compression
mechanism (23) being arranged in a wide opening section (5A)
of said housing (3), and a compression mechanism driving
section (11) being arranged in a narrow section (5D, 5E, 5F) ,
characterized in that a concave section (51) is formed on the
outside of a compression mechanism support surface (5B),
positioned on a bottom surface of said wide opening section
(5A) to support said compression mechanism (23).
2. A fluid machine (1) as claimed in claim 1, wherein said
concave section (51) and an interior space of said narrow
section (5D, 5E, 5F) are communicated with each other.
3. A fluid machine (1) as claimed in claim 1, wherein said
concave section (51) has an arc shape.
4. A fluid machine (1) as claimed in claim 3, wherein said
concave section (51) is formed by casting surface.
5. A fluid machine (1) as claimed in claim 1, wherein said
compression mechanism (23) is a scroll compression mechanism,
and said compression mechanism support surface (5B) is a

thrust receiving surface.
6. A fluid machine (1) as claimed in claim 1, wherein
said housing (3) is a low pressure side housing (5)
provided with a suction port (45), and
said compression mechanism support surface (5B) is a
thrust receiving surface.

The invention discloses a fluid machine (1) in which a
compression mechanism (23) is housed and installed within a
funnel shaped housing (3), a compression mechanism main body
(25, 27) of said compression mechanism (23) being arranged in
a wide opening section (5A) of said housing (3), and a
compression mechanism driving section (11) being arranged in a
narrow section (5D, 5E, 5F) , characterized in that a concave
section (51) is formed on the outside of a compression
mechanism support surface (5B), positioned on a bottom surface
of said wide opening section (5A) to support said compression
mechanism (23).