U.S. patent application number 10/570482 was filed with the patent office on 2007-04-12 for variable displacement type compressor.
Invention is credited to Fuminobu Enokijima, Tetsuhiko Furanuma, Takayuki Imai, Hajime Kurita, Masakazu Murase, Masaki Ota.
Application Number | 20070081904 10/570482 |
Document ID | / |
Family ID | 34277688 |
Filed Date | 2007-04-12 |
United States Patent
Application |
20070081904 |
Kind Code |
A1 |
Kurita; Hajime ; et
al. |
April 12, 2007 |
Variable displacement type compressor
Abstract
A first swash plate 18 is coupled to a drive shaft 16 to be
rotatable integrally with the drive shaft 16. Single head pistons
23 are coupled to the first swash plate 18 via shoes 25A, 25B.
Rotation of the drive shaft 16 rotates the first swash plate 18,
which causes the pistons 23 to reciprocate and compress refrigerant
gas. The first swash plate 18 supports an annular second swash
plate 51 to be rotatable relative to the first swash plate 18 via a
ball bearing 52. The second swash plate 51 is arranged between the
first swash plate 18 and the shoes 25B that receive a compressive
load to be slidable with respect to the first swash plate 18 and
the shoes 25B. Inclined surfaces (chamfers) are provided on salient
corners 18b, 18c of the first swash plate 18. Therefore, the
durability of the swash plates and the shoes are improved.
Inventors: |
Kurita; Hajime; (Kariya-shi,
JP) ; Imai; Takayuki; (Kariya-shi, JP) ;
Murase; Masakazu; (Kariya-shi, JP) ; Furanuma;
Tetsuhiko; (Kariya-shi, JP) ; Ota; Masaki;
(Kariya-shi, JP) ; Enokijima; Fuminobu;
(Kariya-shi, JP) |
Correspondence
Address: |
MORGAN & FINNEGAN, L.L.P.
3 WORLD FINANCIAL CENTER
NEW YORK
NY
10281-2101
US
|
Family ID: |
34277688 |
Appl. No.: |
10/570482 |
Filed: |
August 6, 2004 |
PCT Filed: |
August 6, 2004 |
PCT NO: |
PCT/JP04/11373 |
371 Date: |
October 17, 2006 |
Current U.S.
Class: |
417/269 ;
92/12.2 |
Current CPC
Class: |
F04B 27/1063 20130101;
F04B 27/1054 20130101 |
Class at
Publication: |
417/269 ;
092/012.2 |
International
Class: |
F04B 27/08 20060101
F04B027/08 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 2, 2003 |
JP |
2003-310291 |
Sep 18, 2003 |
JP |
2003-326962 |
Claims
1. A variable displacement swash plate type compressor, comprising
a drive shaft, a swash plate coupled to the drive shaft to be
rotatable integrally with the drive shaft, pistons coupled to the
swash plate via shoes, rotation of the drive shaft rotates the
swash plate, which causes the pistons to reciprocate and compress
gas, and the displacement is changed by varying the inclination
angle of the swash plate, and an inclined surface provided at part
of the entire outer circumferential edge portion of the swash
plate.
2. The compressor according to claim 1, wherein part of the outer
circumferential edge portion of the swash plate corresponding to
the piston located at the top dead center position is provided with
the inclined surface on a salient corner opposite to the
piston.
3. The compressor according to claim 1, wherein part of the outer
circumferential edge portion of the swash plate corresponding to
the piston located at the bottom dead center position is provided
with the inclined surface on a salient corner toward the
piston.
4. The compressor according to claim 1, wherein the swash plate
includes a first swash plate, which is coupled to the drive shaft
to be rotatable integrally with the drive shaft, and a second swash
plate supported by the first swash plate, the pistons are coupled
to the first and second swash plates via first shoes, which abut
against the first swash plate, and second shoes, which abut against
the second swash plate and receive a reaction force of compression,
and part of the outer circumferential edge of the first swash plate
corresponding to the piston located at the top dead center position
is provided with the inclined surface on a salient corner opposite
to the second swash plate.
5. The compressor according to claim 4, wherein part of the outer
circumferential edge portion of the first swash plate corresponding
to the piston located at the bottom dead center position is
provided with the inclined surface on a salient corner toward the
second swash plate.
6. The compressor according to claim 1, wherein the gas is
refrigerant used in a refrigeration circuit, and carbon dioxide is
used as the refrigerant.
7. A variable displacement swash plate type compressor, comprising
a drive shaft, a swash plate coupled to the drive shaft to be
rotatable integrally with the drive shaft, pistons coupled to the
swash plate via shoes, rotation of the drive shaft rotates the
swash plate, which causes the pistons to reciprocate and compress
gas, and the displacement is changed by varying the inclination
angle of the swash plate, a first inclined surface provided at part
of the outer circumferential edge portion of the swash plate
corresponding to the piston located at the top dead center position
on a salient corner opposite to the piston, and a second inclined
surface provided at part of the outer circumferential edge portion
of the swash plate corresponding to the piston located at the
bottom dead center position on a salient corner toward the piston.
Description
TECHNICAL FIELD
[0001] The present invention relates to a variable displacement
swash plate type compressor that forms, for example, part of a
refrigeration circuit and compresses refrigerant gas.
BACKGROUND ART
[0002] As shown in FIG. 9, such a swash plate type compressor
includes a swash plate 92, which is coupled to a drive shaft 91 to
be rotatable integrally with the drive shaft 91. Single head
pistons 94 are coupled to the outer circumferential portion of the
swash plate 92 with pairs of semispherical shoes 93A, 93B.
Therefore, when the swash plate 92 is rotated by rotation of the
drive shaft 91, the swash plate 92 slides with respect to the shoes
93A, 93B causing the pistons 94 to reciprocate, thereby compressing
refrigerant gas.
[0003] Each pair of shoes 93A, 93B rotates about an axis S (a line
that passes through the center of curvature P of the spherical
surface and is perpendicular to sliding surfaces with respect to
the swash plate 92) as the shoes 93A, 93B rotate relative to the
swash plate 92. The rotation of the shoes 93A, 93B about the axis S
is caused because a rotational force is applied to the shoes 93A,
93B in one direction about the axis S due to the difference between
the circumferential velocities of the inner and outer
circumferences of the swash plate 92. More specifically, the
circumferential velocity of the outer circumference of the swash
plate 92 is greater than that of the inner circumference of the
swash plate 92.
[0004] That is, the swash plate type compressor shown in FIG. 9 is
configured such that the shoes 93A, 93B directly slide against the
swash plate 92. Therefore, the shoes 93A, 93B are unnecessarily
rotated about the axis S due to the sliding motion caused as the
shoes 93A, 93B rotate relative to the swash plate 92. This
increases the mechanical loss particularly at the sliding portion
between each piston 94 and the corresponding shoe 93B that receives
reactive force of compression, and causes problems such as seizure
at the sliding portions.
[0005] To solve such problems, for example, a technique shown in
FIG. 10 has been proposed (for example, patent document 1). That
is, an annular step 90a is provided at the center of a rear surface
(a surface facing rightward in FIG. 10) of a swash plate
(hereinafter, referred to as a first swash plate 90). An annular
sliding plate (hereinafter, referred to as a second swash plate 95)
is arranged outward of the step 90a of the first swash plate 90.
The second swash plate 95 is supported to be coaxial with and
rotatable relative to the first swash plate 90. The outer
circumferential portion of the second swash plate 95 is arranged
between the first swash plate 90 and the second shoes 93B to be
slidable with respect to the first swash plate 90 and the second
shoes 93B.
[0006] Therefore, when the first swash plate 90 is rotated, the
first swash plate 90 slides relative to the second swash plate 95,
which reduces the rotation speed of the second swash plate 95 as
compared to the rotation speed of the first swash plate 90. This
reduces the relative rotation speed of the second swash plate 95
and the second shoes 93B as compared to the relative rotation speed
of the second shoes 93B and the first swash plate 90. As a result,
the rotation of each second shoe 93B about the axis S caused by the
relative rotation of the second swash plate 95 and the second shoes
93B is suppressed, which suppresses mechanical loss and occurrence
of problems.
[0007] A configuration has also been proposed in which rolling
elements are provided between the first shoes 93A and the second
shoes 93B and between the first swash plate 90 and the second swash
plate 95 (for example, patent document 2). In the patent document
2, a race of a thrust bearing arranged toward the second shoe 93B
can be considered as the second swash plate 95. With this
configuration, the first swash plate 90 reliably slides with
respect to the second swash plate 95, which significantly reduces
the relative rotation speed of the second swash plate 95 and the
second shoes 93B as compared to the relative rotation speed of the
second shoes 93B and the first swash plate 90.
[0008] However, according to the swash plate configuration
including the second swash plate 95 and the rolling element in
addition to the first swash plate 90, the thickness between the
first shoes 93A and the second shoes 93B is increased. The first
swash plate 90, which tilts with respect to the drive shaft 91, has
a salient corner 90b at the outer circumferential edge portion
corresponding to the vicinity of the piston 94 located at the top
dead center position (the state shown in FIG. 10). The salient
corner 90b is provided at the outer circumferential edge portion
opposite to the second swash plate 95 and significantly protrudes
in the radial direction (upward in the drawing) of the drive shaft
91. Furthermore, the second swash plate 95, which tilts with
respect to the drive shaft 91, has a salient corner 95b at the
outer circumferential edge portion corresponding to the vicinity of
the piston 94 located at the bottom dead center position (not
shown). The salient corner 95b is provided at the outer
circumferential edge portion opposite to the first swash plate 90
and significantly protrudes in the radial direction of the drive
shaft 91.
[0009] When the salient corner 90b of the first swash plate 90 and
the salient corner 95b of the second swash plate 95 significantly
protrude in the radial direction of the drive shaft 91, part of
each piston 94 corresponding to the protruding portions needs to be
made thin, or the pistons 94 need to be enlarged in the radial
direction to avoid interference with the protruding portions.
Reducing the thickness of the pistons 94 leads to reduction in the
durability, and enlargement of the pistons 94 leads to enlargement
of the swash plate type compressor. Therefore, in the prior art,
when the thickness of the swash plate configuration needs to be
increased, the radii of the first swash plate 90 and the second
swash plate 95 are reduced to avoid interference of the salient
corners 90b, 95b with the pistons 94.
[0010] However, when the radii of the first swash plate 90 and the
second swash plate 95 are reduced, particularly the piston 94
located in the vicinity of the top dead center position (in a
compression stroke) has a reduced contact area between the second
shoe 93B, which receives a significant reaction force of
compression, and the second swash plate 95. This undesirably
reduces the durability of the second swash plate 95 and the second
shoe 93B.
[0011] It has become a common practice to use carbon dioxide as
refrigerant of the refrigeration circuit. When carbon dioxide
refrigerant is used, the pressure in the refrigeration circuit
becomes extremely high as compared to a case where
chlorofluorocarbon refrigerant (for example, R134a) is used.
Therefore, the reaction force of compression applied to the pistons
94 is increased in the swash plate type compressor, and the
aforementioned problem (reduction in the durability of the second
swash plate 95 and the second shoes 93B) has become a significant
matter of concern.
[0012] Patent Document 1: Japanese Laid-Open Patent Publication No.
8-338363 (page 4, FIG. 1)
[0013] Patent Document 2: Japanese Laid-Open Patent Publication No.
8-28447 (page 3, FIG. 1)
SUMMARY OF THE INVENTION
[0014] Accordingly, it is an objective of the present invention to
provide a variable displacement swash plate type compressor that
improves the durability of a swash plate and shoes while
suppressing reduction in the durability of pistons and enlargement
of the pistons.
[0015] To achieve the above objective, the present invention
provides a variable displacement swash plate type compressor. A
swash plate is coupled to a drive shaft to be rotatable integrally
with the drive shaft. Pistons are coupled to the swash plate via
shoes. Rotation of the drive shaft rotates the swash plate, which
causes the pistons to reciprocate and compress gas. The
displacement is changed by varying the inclination angle of the
swash plate. An inclined surface is provided at part of the entire
outer circumferential edge portion of the swash plate.
[0016] Providing the inclined surface at a projecting salient
corner of the outer circumferential edge portion of the swash
plate, which inclines with respect to the drive shaft, permits the
diameter of the swash plate to be increased while suppressing
decrease of the durability and enlargement of the pistons.
Therefore, a significant reaction force of compression applied to
the swash plate via the shoes is received in a suitable manner.
This improves the durability of the swash plate and the shoes.
[0017] In a preferred embodiment, part of the outer circumferential
edge portion of the swash plate corresponding to the piston located
at the top dead center position is provided with the inclined
surface on a salient corner opposite to the piston. That is, part
of the outer circumferential edge portion of the swash plate
corresponding to a circumferential range of the swash plate that
arranges any of the pistons at the top dead center position is
provided with the inclined surface on the salient corner opposite
to the piston.
[0018] At the outer circumferential edge portion of the swash plate
that corresponds to the piston located at the top dead center
position, the salient corner opposite to the piston significantly
projects in the radial direction of the drive shaft when the swash
plate tilts with respect to the drive shaft. Therefore, a
significant reaction force of compression applied to the swash
plate via the shoe of the piston located in the vicinity of the top
dead center position is received in a suitable manner. This
improves the durability of the swash plate and the shoes.
[0019] In a preferred embodiment, part of the outer circumferential
edge portion of the swash plate corresponding to the piston located
at the bottom dead center position is provided with the inclined
surface on a salient corner toward the piston. That is, part of the
outer circumferential edge portion of the swash plate corresponding
to a circumferential range of the swash plate that arranges any of
the pistons at the bottom dead center position is provided with the
inclined surface on the salient corner toward the piston.
[0020] At the outer circumferential edge portion of the swash plate
corresponding to the piston located at the bottom dead center
position, the salient corner toward the piston significantly
projects in the radial direction of the drive shaft. Therefore,
chamfering the projecting portion of the swash plate permits the
diameter of the first swash plate to be increased while suppressing
decrease of the durability and enlargement of the pistons.
[0021] In the preferred embodiment, the swash plate includes a
first swash plate, which is coupled to the drive shaft to be
rotatable integrally with the drive shaft, and a second swash
plate, which is supported by the first swash plate. The pistons are
coupled to the first and second swash plates via first shoes, which
abut against the first swash plate, and second shoes, which abut
against the second swash plate and receive a reaction force of
compression. Part of the outer circumferential edge of the first
swash plate corresponding to the piston located at the top dead
center position is provided with the inclined surface on a salient
corner opposite to the second swash plate. That is, part of the
outer circumferential edge portion of the first swash plate
corresponding to a circumferential range of the first swash plate
that arranges any of the pistons at the top dead center position is
provided with the inclined surface on the salient corner opposite
to the first swash plate.
[0022] At the outer circumferential edge portion of the first swash
plate that corresponds to the piston located at the top dead center
position, the salient corner opposite to the second swash plate
significantly projects in the radial direction of the drive shaft
when the first swash plate tilts with respect to the drive shaft.
Therefore, chamfering the projecting portion of the first swash
plate permits the diameter of the first swash plate to be increased
while suppressing decrease of the durability and enlargement of the
pistons. Therefore, the first swash plate supports the second swash
plate in a suitable manner, and a great reaction force of
compression applied to the second swash plate via the second shoe
of the piston located in the vicinity of the top dead center
position is received by the first swash plate via the second swash
plate in a suitable manner. This improves the durability of the
second swash plate and the second shoes.
[0023] In the preferred embodiment, part of the outer
circumferential edge portion of the first swash plate corresponding
to the piston located at the bottom dead center position is
provided with the inclined surface on a salient corner toward the
second swash plate. That is, part of the outer circumferential edge
portion of the first swash plate corresponding to a circumferential
range of the first swash plate that arranges any of the pistons at
the bottom dead center position is provided with the inclined
surface on the salient corner toward the second swash plate.
[0024] At the outer circumferential edge portion of the swash plate
corresponding to the piston located at the bottom dead center
position, the salient corner toward the piston significantly
projects in the radial direction of the drive shaft. Therefore,
chamfering the projecting portion of the swash plate permits the
diameter of the first swash plate to be increased while suppressing
decrease of the durability and enlargement of the pistons.
[0025] In the preferred embodiment, the gas is refrigerant used in
a refrigeration circuit, and carbon dioxide is used as the
refrigerant.
[0026] When carbon dioxide refrigerant is used, as compared to a
case where chlorofluorocarbon refrigerant (for example, R134a) is
used, the pressure in the refrigeration circuit becomes extremely
high. Therefore, the reaction force of compression applied to the
pistons in the variable displacement swash plate type compressor is
increased, which increases the pressure between the swash plate and
the shoes. The above mentioned embodiments of the present invention
according to any one of claims 1 to 5 are particularly effective in
improving the durability of the swash plate and the shoes while
suppressing decrease of the durability and enlargement of the
pistons.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 is a longitudinal cross-sectional view illustrating a
variable displacement swash plate type compressor according to a
first embodiment of the present invention;
[0028] FIG. 2 is an enlarged partial view of FIG. 1 with the first
and second swash plates not being sectioned;
[0029] FIG. 3 is a longitudinal cross-sectional view illustrating a
variable displacement swash plate type compressor according to a
second embodiment of the present invention;
[0030] FIG. 4 is an enlarged partial view of FIG. 3 with the first
and second swash plates not being sectioned (partially cut away)
and part of the first and second shoes being sectioned;
[0031] FIG. 5 is an enlarged partial view illustrating a swash
plate configuration according to a third embodiment of the present
invention;
[0032] FIG. 6 is a longitudinal cross-sectional view illustrating a
variable displacement swash plate type compressor according to a
fourth embodiment of the present invention;
[0033] FIG. 7 is a cross-sectional view taken along line A-A of
FIG. 6;
[0034] FIG. 8 is an enlarged partial cross-sectional view of FIG.
6;
[0035] FIG. 9 is a longitudinal cross-sectional view illustrating a
prior art variable displacement swash plate type compressor;
and
[0036] FIG. 10 is a partial cross-sectional view illustrating a
prior art technique.
BEST MODE FOR CARRYING OUT THE INVENTION
[0037] A variable displacement swash plate type compressor
according to first to fourth embodiments of the present invention
will now be described. The compressor forms part of a refrigeration
circuit of a vehicle air-conditioning system.
[0038] The first embodiment will be described with reference to
FIGS. 1 and 2.
[0039] FIG. 1 is a longitudinal cross-sectional view of the
variable displacement swash plate type compressor (hereinafter,
simply referred to as the compressor) 10. The left end of the
compressor 10 in FIG. 1 is defined as the front of the compressor
10, and the right end is defined as the rear of the compressor
10.
[0040] As shown in FIG. 1, a housing of the compressor 10 includes
a cylinder block 11, a front housing member 12 secured to the front
end of the cylinder block 11, and a rear housing member 14 secured
to the rear end of the cylinder block 11 with a valve plate
assembly 13 in between.
[0041] In the housing of the compressor 10, the cylinder block 11
and the front housing member 12 define a crank chamber 15. A drive
shaft 16 is rotatably arranged between the cylinder block 11 and
the front housing member 12 and extends through the crank chamber
15. The drive shaft 16 is coupled to a power source of the vehicle,
which is an engine E in this embodiment, through a clutchless type
power transmission mechanism PT, which constantly transmits power.
Therefore, the drive shaft 16 is always rotated by the power supply
from the engine E when the engine E is running.
[0042] A rotor 17 is coupled to the drive shaft 16 and is located
in the crank chamber 15. The rotor 17 rotates integrally with the
drive shaft 16. The crank chamber 15 accommodates a substantially
disk-like first swash plate 18. A through hole 18a is formed at the
center of the first swash plate 18. The drive shaft 16 is inserted
through the through hole 18a of the first swash plate 18. The first
swash plate 18 is supported by the drive shaft 16 via the through
hole 18a to be slidable and tiltable with respect to the drive
shaft 16. A hinge mechanism 19 is located between the rotor 17 and
the first swash plate 18.
[0043] The hinge mechanism 19 includes two rotor protrusions 41
(one of the protrusions 41 located toward the front of the sheet of
FIG. 1 is not shown), which protrude from the rear surface of the
rotor 17, and a swash plate protrusion 42, which protrudes from the
front surface of the first swash plate 18 toward the rotor 17. The
distal end of the swash plate protrusion 42 is inserted between the
two rotor protrusions 41. Therefore, rotational force of the rotor
17 is transmitted to the first swash plate 18 via the rotor
protrusions 41 and the swash plate protrusion 42.
[0044] A substantially cylindrical support portion 39 projects at
the center of the rear surface of the first swash plate 18 to
surround the drive shaft 16. A disk-like second swash plate 51 is
arranged outward of the support portion 39 of the first swash plate
18. A support hole 51a is formed at the center of the second swash
plate 51. The support portion 39 is inserted in the support hole
51a. The radius of the second swash plate 51 is substantially the
same as that of the first swash plate 18.
[0045] A radial bearing 52 is provided between the outer
circumferential surface of the support portion 39 and the inner
circumferential surface of the support hole 51a of the second swash
plate 51. A thrust bearing 53 is provided between the rear surface
of the first swash plate 18 and the front surface of the second
swash plate 51. The thrust bearing 53 has rolling elements, which
are rollers 53a in this embodiment, and the rollers 53a are
rotatably held by a retainer 53b.
[0046] The second swash plate 51 is supported by the first swash
plate 18 (the support portion 39) via the radial bearing 52 and the
thrust bearing 53 such that the second swash plate 51 rotates
relative to and tilt integrally with the first swash plate 18.
[0047] A cam portion 43 is formed at the proximal end of the rotor
protrusions 41. A cam surface 43a is formed on the rear end face of
the cam portion 43 facing the first swash plate 18. The distal end
of the swash plate protrusion 42 slidably abuts against the cam
surface 43a of the cam portion 43. Therefore, the hinge mechanism
19 guides the inclination of the first swash plate 18 and the
second swash plate 51 as the distal end of the swash plate
protrusion 42 moves toward and apart from the drive shaft 16 along
the cam surface 43a of the cam portion 43.
[0048] Cylinder bores 22 are formed in the cylinder block 11 about
the axis L of the drive shaft 16 at equal angular intervals and
extend in the front-rear direction (left-right direction on the
sheet of FIG. 1). A single head piston 23 is accommodated in each
cylinder bore 22 to be movable in the front-rear direction. The
front and rear openings of each cylinder bore 22 are closed by the
front end face of the valve plate assembly 13 and the associated
piston 23. Each cylinder bore 22 defines a compression chamber 24.
The volume of each compression chamber 24 changes according to the
reciprocation of the corresponding piston 23.
[0049] Each piston 23 is formed by coupling, in the front-rear
direction, a columnar head portion 37, which is inserted in the
associated cylinder bore 22, and a neck 38 located in the crank
chamber 15 outside the cylinder bore 22. The head portions 37 and
the necks 38 are formed of an aluminum based metal material (pure
aluminum or an aluminum alloy). A pair of shoe seats 38a are formed
in each neck 38. Each neck 38 accommodates semispherical first and
second shoes 25A, 25B. The first shoe 25A and the second shoe 25B
are formed of iron based metal material. In this specification,
"semisphere" refers not only to a half of a sphere, but also to a
shape that includes part of a spherical surface of a sphere.
[0050] The first shoe 25A and the second shoe 25B are each received
by the corresponding shoe seat 38a via a semispherical surface 25a.
The semispherical surface 25a of the first shoe 25A and the
semispherical surface 25a of the second shoe 25B are located on the
same spherical surface defined about a point P. Each piston 23 is
coupled to the outer circumferential portion of the first swash
plate 18 and the second swash plate 51 via the first shoe 25A and
the second shoe 25B. The first shoe 25A located opposite to the
compression chamber 24 abuts against the front surface of the first
swash plate 18 via a planar sliding surface 25b provided opposite
to the semispherical surface 25a. The second shoe 25B located
toward the compression chamber 24, that is, the one that receives
reaction force of compression abuts against the rear surface of the
second swash plate 51 via a sliding surface 25b provided opposite
to the semispherical surface 25a.
[0051] When the first swash plate 18 is rotated by the rotation of
the drive shaft 16, the pistons 23 reciprocate in the front-rear
direction.
[0052] When the first swash plate 18 is rotated, the radial bearing
52 and the thrust bearing 53 cause the first swash plate 18 to
slide with respect to the second swash plate 51. This reduces the
rotation speed of the second swash plate 51 as compared to the
rotation speed of the first swash plate 18. Therefore, the relative
rotation speed of the second swash plate 51 and the second shoes
25B is reduced as compared to the relative rotation speed of the
second shoes 25B and the first swash plate 18. This suppresses the
rotation of each second shoe 25B about the axis S (a line that
passes through the center of curvature point P of the semispherical
surface 25a and is perpendicular to the sliding surface 25b) caused
by the relative rotation of the second swash plate 51 and the
second shoe 25B. Thus, mechanical loss and occurrence of problems
caused by the rotation of the second shoes 25B are suppressed.
[0053] An intake chamber 26 and a discharge chamber 27 are defined
between the valve plate assembly 13 and the rear housing member 14
in the housing of the compressor 10. The valve plate assembly 13
includes intake ports 28 and intake valves 29 located between the
compression chambers 24 and the intake chamber 26. The valve plate
assembly 13 also includes discharge ports 30 and discharge valves
31 located between the compression chambers 24 and the discharge
chamber 27.
[0054] As refrigerant of the refrigeration circuit, carbon dioxide
is used. Refrigerant gas introduced into the intake chamber 26 from
an external circuit, which is not shown, is drawn into each
compression chamber 24 via the associated intake port 28 and the
intake valve 29 as the corresponding piston 23 moves from the top
dead center position to the bottom dead center position. The
refrigerant gas that is drawn into the compression chamber 24 is
compressed to a predetermined pressure as the piston 23 is moved
from the bottom dead center position to the top dead center
position, and is discharged to the discharge chamber 27 through the
associated discharge port 30 and the discharge valve 31. The
refrigerant gas in the discharge chamber 27 is then conducted to
the external circuit.
[0055] A bleed passage 32, a supply passage 33, and a control valve
34 are provided in the housing of the compressor 10. The bleed
passage 32 connects the crank chamber 15 to the intake chamber 26.
The supply passage 33 connects the discharge chamber 27 to the
crank chamber 15. The control valve 34, which is a conventional
electromagnetic valve, is located in the supply passage 33.
[0056] The opening degree of the control valve 34 is adjusted by
controlling power supply from the outside to control the balance
between the flow rate of highly pressurized discharge gas supplied
to the crank chamber 15 through the supply passage 33 and the flow
rate of gas conducted out of the crank chamber 15 through the bleed
passage 32. The pressure in the crank chamber 15 is thus
determined. As the pressure in the crank chamber 15 varies, the
difference between the pressure in the crank chamber 15 and the
pressure in the compression chamber 24 is changed, which in turn
varies the inclination angle of the first swash plate 18 and the
second swash plate 51. Accordingly, the stroke of each piston 23,
or the compressor displacement is adjusted.
[0057] For example, when the opening degree of the control valve 34
is reduced, the pressure in the crank chamber 15 is reduced.
Therefore, the inclination angle of the first swash plate 18 and
the second swash plate 51 increases, thereby increasing the stroke
of each piston 23. Thus, the displacement of the compressor 10 is
increased. In contrast, when the opening degree of the control
valve 34 increases, the pressure in the crank chamber 15 is
increased. Therefore, the inclination angle of the first swash
plate 18 and the second swash plate 51 is reduced, thereby reducing
the stroke of each piston 23. Thus, the displacement of the
compressor 10 is reduced.
[0058] As shown in FIGS. 1 and 2, the support portion 39 of the
first swash plate 18 supporting the second swash plate 51 is
provided at a position decentered from the axis M1 of the first
swash plate 18 toward the piston 23A located at the top dead center
position. In other words, the support portion 39 is provided at a
position decentered toward a section of the first swash plate
(toward the hinge mechanism 19) that causes any of the pistons 23
to be located at the top dead center position as viewed in the
radial direction of the first swash plate 18 from the axis M1.
Therefore, the second swash plate 51, the radial bearing 52, and
the thrust bearing 53 (and the retainer 53b) are decentered from
the first swash plate 18 toward the piston 23A located at the top
dead center position. Therefore, the axis M2 of the second swash
plate 51, the radial bearing 52, and the thrust bearing 53 is
slightly displaced in parallel from the axis M1 of the first swash
plate 18 toward the center point P of the first shoe 25A and the
second shoe 25B of the piston 23A located at the top dead center
position (for example, 0.05 to 5 mm, although the displacement is
exaggerated in FIGS. 1 and 2).
[0059] Therefore, part of the outer circumferential edge portion of
the second swash plate 51 corresponding to the vicinity of the
piston 23A located at the top dead center position slightly
protrudes in the radial direction of the first swash plate 18 from
the outer circumferential edge portion of the first swash plate 18.
Therefore, for example, as compared to a case where the second
swash plate 51 is not decentered from the first swash plate 18, the
contact area between the second shoe 25B of the piston 23 located
in the vicinity of the top dead center position and the second
swash plate 51 is increased.
[0060] Part of the outer circumferential edge portion of the second
swash plate 51 corresponding to the vicinity of the piston 23B
located at the bottom dead center position is located radially
inward of the first swash plate 18 from the outer circumferential
edge portion of the first swash plate 18. That is, part of the
outer circumferential edge portion of the second swash plate 51
corresponding to the vicinity of the hinge mechanism 19 is located
radially inward of the first swash plate 18 than the outer
circumferential edge portion of the first swash plate 18.
Therefore, for example, as compared to a case where the second
swash plate 51 is not decentered from the first swash plate 18, the
contact area between the second shoe 25B of the piston 23 located
in the vicinity of the bottom dead center position and the second
swash plate 51 is reduced. However, the reaction force of
compression applied to the second shoe 25B of the piston 23 located
in the vicinity of the bottom dead center position is far smaller
than the reaction force of compression applied to the second shoe
25B of the piston 23 located in the vicinity of the top dead center
position. Therefore, even if the contact area between the second
shoe 25B of the piston 23 located in the vicinity of the bottom
dead center position and the second swash plate 51 is reduced, no
problem arises in the durability of the second swash plate 51 and
the second shoe 25B.
[0061] Part of the outer circumferential edge portion of the first
swash plate 18 corresponding to the piston 23A located at the top
dead center position and circumferentially adjacent parts thereof
are provided with an inclined surface (a chamfer) on a salient
corner 18b opposite to the second swash plate 51. That is, part of
the outer circumferential edge portion of the second swash plate 51
corresponding to the vicinity of the hinge mechanism 19 is provided
with the inclined surface (the chamfer) on the salient corner 18b
opposite to the second swash plate 51. In other words, part of the
outer circumferential edge portion of the first swash plate 18
corresponding to a circumferential range of the first swash plate
18 that arranges any of the pistons 23 at the top dead center
position is provided with the inclined surface on the salient
corner 18b opposite to the piston 23A. The inclined surface (the
chamfer) on the salient corner 18b is the largest at the part
corresponding to the piston 23A located at the top dead center
position, and gradually becomes smaller along the circumferential
direction. The inclined surface (the chamfer) on the salient corner
18b is provided within a range of quarter to half the circumference
of the first swash plate 18 with the part corresponding to the
piston 23A located at the top dead center position arranged in the
middle.
[0062] Part of the outer circumferential edge portion of the first
swash plate 18 corresponding to the piston 23B located at the
bottom dead center position and circumferentially adjacent parts
thereof are provided with an inclined surface (a chamfer) on a
salient corner 18c toward the second swash plate 51. That is, part
of the outer circumferential edge portion of the first swash plate
18 corresponding to a circumferential range of the first swash
plate 18 that arranges the piston 23B at the bottom dead center
position is provided with the inclined surface on the salient
corner 18c opposite to the piston 23B.
[0063] The inclined surface (the chamfer) is the largest at the
part corresponding to the piston 23B located at the bottom dead
center position, and gradually becomes smaller along the
circumferential direction. The inclined surface (the chamfer) of
the salient corner 18c is provided within a range of quarter to
half the circumference of the first swash plate 18 with the part
corresponding to the piston 23B located at the bottom dead center
position arranged in the middle. The inclined surface (the chamfer)
on the salient corner 18c is substantially the same size as the
inclined surface (the chamfer) on the salient corner 18b taking
into consideration of the balance of the weight around the axis M1
of the first swash plate 18.
[0064] The first embodiment has the following advantages.
[0065] (1-1) The second swash plate 51 is decentered from the first
swash plate 18 toward the piston 23A located at the top dead center
position. Therefore, the contact area between the second shoe 25B
of the piston 23 located in the vicinity of the top dead center
position and the second swash plate 51 is increased without
increasing the diameter of the first swash plate 18 and the second
swash plate 51. Therefore, the second swash plate 51 reliably
slides with respect to the second shoes 25B, and the durability of
the second swash plate 51 and the second shoes 25B is improved
while suppressing decrease of the durability and enlargement of the
pistons 23.
[0066] (1-2) According to the swash plate configuration that
includes the thrust bearing 53 in addition to the first swash plate
18 and the second swash plate 51 as in the first embodiment, the
thickness of the swash plate configuration between the first shoes
25A and the second shoes 25B is increased. In such a configuration
with a severe condition, decentering the second swash plate 51 with
respect to the first swash plate 18 to increase the contact area
between the second shoe 25B of the piston 23 located in the
vicinity of the top dead center position and the second swash plate
51 is particularly effective in improving the durability of the
second swash plate 51 and the second shoes 25B while suppressing
decrease of the durability and the enlargement of the pistons
23.
[0067] (1-3) Part of the outer circumferential edge portion of the
first swash plate 18 corresponding to the piston 23A located at the
top dead center position is provided with the inclined surface on
the salient corner 18b opposite to the second swash plate 51. Also,
part of the outer circumferential edge portion of the first swash
plate 18 corresponding to the piston 23B located at the bottom dead
center position is provided with the inclined surface on the
salient corner 18c toward the second swash plate 51. At the outer
circumferential edge portion of the first swash plate 18 that
corresponds to the piston 23A located at the top dead center
position, the salient corner 18b opposite to the second swash plate
51 significantly projects in the radial direction of the drive
shaft 16 when the first swash plate 18 tilts with respect to the
drive shaft 16. Also, at the outer circumferential edge portion of
the first swash plate 18 corresponding to the piston 23B located at
the bottom dead center position, the salient corner 18c toward the
second swash plate 51 significantly projects in the radial
direction of the drive shaft 16.
[0068] Therefore, providing the inclined surfaces at the projecting
portions of the first swash plate 18 (part of the entire
circumference of the salient corners 18b, 18c) permits the diameter
of the first swash plate 18 to be increased while suppressing
decrease of the durability and enlargement of the pistons 23.
Therefore, the first swash plate 18 supports the second swash plate
51 in a suitable manner, and a great reaction force of compression
applied to the second swash plate 51 via the second shoe 25B of the
piston 23 located in the vicinity of the top dead center position
is received by the first swash plate 18 via the second swash plate
51 in a suitable manner. This improves the durability of the second
swash plate 51.
[0069] (1-4) As the refrigerant of the refrigeration circuit,
carbon dioxide is used. When carbon dioxide refrigerant is used,
the pressure in the refrigeration circuit becomes extremely high as
compared to a case where chlorofluorocarbon refrigerant (for
example, R134a) is used. Therefore, the reaction force of
compression applied to the pistons 23 in the compressor is
increased, which increases the pressure between the second swash
plate 51 and the second shoes 25B. The first embodiment of the
present invention is thus particularly effective in improving the
durability of the second swash plate 51 and the second shoes 25B
while suppressing decrease of the durability and enlargement of the
pistons 23.
[0070] Next, a second embodiment of the present invention will be
described with reference to FIGS. 3 and 4. In the second
embodiment, only differences from the first embodiment are
explained. Like or the same members are given the like or the same
numbers and detailed explanations are omitted.
[0071] As for the first shoes 25A and the second shoes 25B, each
first shoe 25A located toward the hinge mechanism 19, or opposite
to the associated compression chamber 24, slidably abuts against
the front surface of an outer circumferential portion 18-1 of the
first swash plate 18 via the sliding surface 25b opposite to the
semispherical surface 25a. Also, each second shoe 25B located
opposite to the hinge mechanism 19, or toward the associated
compression chamber 24, and receives the reaction force of
compression slidably abuts against the rear surface of an outer
circumferential portion 51-2 of the second swash plate 51 via the
sliding surface 25b opposite to the semispherical surface 25a. The
center portion of the sliding surface 25b of the first shoe 25A
bulges toward the first swash plate 18 (see FIG. 4. The bulge is
exaggerated in FIG. 4). The sliding surface 25b of the second shoe
25B is flat.
[0072] A radial bearing 52A, which is a roller bearing, is located
between the support portion 39, which forms the inner
circumferential portion of the first swash plate 18, and an inner
circumferential portion 51-1 of the second swash plate 51, and more
specifically, between the outer circumferential surface of the
support portion 39 and the inner circumferential surface of the
support hole 51a of the second swash plate 51. The radial bearing
52A includes an outer race 52a attached to the inner
circumferential surface of the support hole 51a of the second swash
plate 51, an inner race 52b attached to the outer circumferential
surface of the support portion 39 of the first swash plate 18, and
rolling elements, which are rollers 52c in the second embodiment.
The rollers 52c are located between the outer race 52a and the
inner race 52b.
[0073] The thrust bearing 53, which is a roller bearing, is located
between the first shoes 25A and the second shoes 25B and between
the outer circumferential portion 18-1 of the first swash plate 18
and the outer circumferential portion 51-2 of the second swash
plate 51. The thrust bearing 53 has rolling elements, which are the
rollers 53a in the second embodiment, and the rollers 53a are
rotatably held by the retainer 53b. The thrust bearing 53 has an
annular race 55 located between the rollers 53a and the first swash
plate 18. The race 55 is formed by carburizing and heat treating
base material formed of mild steel such as SPC. The corners at both
ends of each roller 53a are chamfered to prevent the second swash
plate 51 and the race 55 from being damaged by the rollers 53a
abutting against the second swash plate 51 and the race 55.
[0074] An annular engaging portion 18d is provided on the rear
surface of the first swash plate 18 at the outermost circumference
of the outer circumferential portion 18-1 and projects toward the
second swash plate 51. The race 55 is located inward of the
engaging portion 18d and is engaged with the first swash plate 18
at the radially outward edge of the race 55 by the abutment between
the outer circumferential edge of the race 55 and the engaging
portion 18d. The race 55 is guided by the engaging portion 18d to
rotate relative to the first swash plate 18.
[0075] The second swash plate 51 is supported by the first swash
plate 18 via the radial bearing 52A and the thrust bearing 53 such
that the second swash plate 51 rotates relative to and tilts
integrally with the first swash plate 18. Therefore, when the first
swash plate 18 is rotated, the radial bearing 52A and the thrust
bearing 53 cause rolling motion between the first swash plate 18
and the second swash plate 51. Therefore, the mechanical loss
caused by sliding motion between the first swash plate 18 and the
second swash plate 51 is converted to the mechanical loss caused by
the rolling motion. This significantly suppresses the mechanical
loss in the compressor.
[0076] The plate thickness Y1 of the inner circumferential portion
51-1 of the second swash plate 51 that is supported by the radial
bearing 52A is greater than the plate thickness Y2 of the outer
circumferential portion 51-2 of the second swash plate 51 that is
supported by the thrust bearing 53. More specifically, the plate
thickness Y2 of the outer circumferential portion 51-2 of the
second swash plate 51 is half or more of the plate thickness X of
the outer circumferential portion 18-1 of the first swash plate 18
and thinner than the plate thickness X of the outer circumferential
portion 18-1 of the first swash plate 18. Also, the plate thickness
Y1 of the inner circumferential portion 51-1 of the second swash
plate 51 is thicker than the plate thickness X of the outer
circumferential portion 18-1 of the first swash plate 18.
[0077] The plate thickness of the inner circumferential portion
51-1 of the second swash plate 51 is designed to be greater than
that of the outer circumferential portion 51-2 of the second swash
plate 51 (Y1>Y2) by providing a cylindrical first projection 56,
which projects toward the first swash plate 18, and a cylindrical
second projection 57, which projects opposite to the first swash
plate 18. The first projection 56 and the second projection 57 are
arranged coaxial with the support hole 51a, and the inner
circumferential surfaces of the first projection 56 and the second
projection 57 form part of the inner circumferential surface of the
support hole 51a. The outer diameter Z2 of the second projection 57
is smaller than the outer diameter Z1 of the first projection 56.
Also, the outer circumferential corner 57a of the distal end face
of the second projection 57 is entirely chamfered to form a tapered
face.
[0078] The second embodiment provides the following advantages in
addition to the advantages of the first embodiment.
[0079] (2-1) The thrust bearing 53, which supports the second swash
plate 51 to be rotatable relative to the first swash plate 18, is
arranged between the first shoes 25A and the second shoes 25B and
between the outer circumferential portion 18-1 of the first swash
plate 18 and the outer circumferential portion 51-2 of the second
swash plate 51. The radial bearing 52A, which supports the second
swash plate 51 to be rotatable relative to the first swash plate
18, is arranged between the inner circumferential portion (the
support portion 39) of the first swash plate 18 and the inner
circumferential portion 51-1 of the second swash plate 51.
[0080] Therefore, the thrust bearing 53 and the radial bearing 52A
effectively reduce the rotational resistance caused between the
outer circumferential portion 18-1 of the first swash plate 18 and
the outer circumferential portion 51-2 of the second swash plate
51, and between the inner circumferential portion (the support
portion 39) of the first swash plate 18 and the inner
circumferential portion 51-1 of the second swash plate 51.
Therefore, even in the compressor 10 used for the refrigeration
circuit that uses carbon dioxide as refrigerant, the sliding motion
between the first swash plate 18 and the second swash plate 51 is
converted to the mechanical loss caused by the rolling motion. As a
result, problems such as the mechanical loss and the seizure are
effectively suppressed.
[0081] (2-2) The plate thickness Y2 of the outer circumferential
portion 51-2 of the second swash plate 51 is half or more of the
plate thickness X of the outer circumferential portion 18-1 of the
first swash plate 18 and thinner than the plate thickness X of the
outer circumferential portion 18-1. To avoid enlargement of the
pistons 23, that is, enlargement of the compressor, a space between
the first shoes 25A and the second shoes 25B is limited. In this
limited space, when the plate thickness X of the outer
circumferential portion 18-1 of the first swash plate 18 is
increased, the plate thickness Y2 of the outer circumferential
portion 51-2 of the second swash plate 51 needs to be reduced. In
contrast, when the plate thickness Y2 of the outer circumferential
portion 51-2 of the second swash plate 51 is increased, the plate
thickness X of the outer circumferential portion 18-1 of the first
swash plate 18 needs to be reduced.
[0082] In terms of receiving the reaction force of compression, the
plate thicknesses X, Y2 of the outer circumferential portions 18-1,
51-2 of the first swash plate 18 and the second swash plate 51 need
to be as thick as possible to secure the strength. However,
securing the plate thickness X of the outer circumferential portion
18-1 of the first swash plate 18 to which power is transmitted from
the drive shaft 16 should take precedence to securing the plate
thickness Y2 of the outer circumferential portion 51-2 of the
second swash plate 51 that is only required to slide with respect
to the first swash plate 18. In this respect, it is suitable to set
the plate thickness Y2 of the outer circumferential portion 51-2 of
the second swash plate 51 to be half or more of the plate thickness
X of the outer circumferential portion 18-1 of the first swash
plate 18 and thinner than the plate thickness X of the outer
circumferential portion 18-1.
[0083] (2-3) In the second swash plate 51, the plate thickness Y1
of the inner circumferential portion 51-1 is greater than the plate
thickness Y2 of the outer circumferential portion 51-2. The thick
inner circumferential portion 51-1 permits the second swash plate
51 to be stably supported by the radial bearing 52A, and improves
the sliding performance between the first swash plate 18 and the
second swash plate 51. Furthermore, since the outer circumferential
portion 51-2 of the second swash plate 51 is relatively thinner
than the inner circumferential portion 51-1, the plate thickness of
the outer circumferential portion 18-1 of the first swash plate 18
that is required to have a greater strength than the second swash
plate 51 is easily secured.
[0084] (2-4) The plate thickness Y2 of the outer circumferential
portion 51-2 of the second swash plate 51 is thinner than the plate
thickness X of the outer circumferential portion 18-1 of the first
swash plate 18. Therefore, the thin outer circumferential portion
51-2 of the second swash plate 51 facilitates securing the plate
thickness of the outer circumferential portion 18-1 of the first
swash plate 18 that is required to have a greater strength than the
second swash plate 51. The plate thickness Y1 of the inner
circumferential portion 51-1 of the second swash plate 51 is
greater than the plate thickness X of the outer circumferential
portion 18-1 of the first swash plate 18. Therefore, the radial
bearing 52A more stably supports the second swash plate 51.
[0085] (2-5) As for the first projection 56 and the second
projection 57, which form the inner circumferential portion 51-1 of
the second swash plate 51, the outer diameter Z2 of the second
projection 57 is less than the outer diameter Z1 of the first
projection 56. When the displacement of the compressor 10 is
maximum (state shown in FIG. 3), for example, part of the second
projection 57 significantly approaches the piston 23B located at
the bottom dead center position. Therefore, it is effective to make
the diameter of the second projection 57 to be smaller than that of
the first projection 56, thereby separating the second projection
57 from the piston 23, in view of avoiding interference between the
second swash plate 51 and the pistons 23 while increasing the plate
thickness Y1 of the inner circumferential portion 51-1 of the
second swash plate 51.
[0086] (2-6) As for the second projection 57, which forms the inner
circumferential portion 51-1 of the second swash plate 51, the
outer circumferential corner 57a of the distal end face is
chamfered. When the displacement of the compressor is maximum, for
example, part of the outer circumferential corner 57a of the distal
end face of the second projection 57 significantly approaches the
piston 23B located at the bottom dead center position. Therefore,
it is effective to provide the chamfer on the outer circumferential
corner 57a of the distal end face of the second projection 57 in
view of avoiding interference between the second swash plate 51 and
the pistons 23 while increasing the plate thickness Y1 of the inner
circumferential portion 51-1 of the second swash plate 51.
[0087] (2-7) Part of the outer circumferential edge of the first
swash plate 18 corresponding to the piston 23A located at the top
dead center position is provided with the inclined surface (the
chamfer) on the salient corner 18b opposite to the second swash
plate 51. Therefore, the first swash plate 18 and the second swash
plate 51 can be enlarged while suppressing reduction in the
durability and enlargement of the pistons 23. Therefore, the second
swash plate 51 reliably slides with respect to the second shoes
25B, and the durability of the second swash plate 51 and the second
shoes 25B is improved while suppressing reduction in the durability
and enlargement of the pistons 23.
[0088] That is, at the outer circumferential edge portion of the
first swash plate 18 that corresponds to the piston 23A located at
the top dead center position, the salient corner 18b (that has not
been chamfered) opposite to the second swash plate 51 significantly
projects in the radial direction of the drive shaft 16 when the
first swash plate 18 tilts with respect to the drive shaft 16. When
the salient corner 18b of the first swash plate 18 opposite to the
second swash plate 51 significantly projects in the radial
direction, the thickness of the necks 38 of the pistons 23 need to
be reduced corresponding to the projecting portion, or the necks 38
need to be enlarged in the radial direction to avoid interference
with the projecting portion. However, reducing the thickness of the
necks 38 leads to reduction in the durability of the pistons 23,
and enlargement of the necks 38 leads to enlargement of the
compressor.
[0089] To solve such problems, the radius of the first swash plate
18 may be reduced to avoid interference between the salient corner
18b and the pistons 23. However, when the radius of the first swash
plate 18 is reduced, the radius of the second swash plate 51, which
needs to be supported by the first swash plate 18, must also be
reduced. Therefore, in particular, the contact area between the
second swash plate 51 and the second shoe 25B of the piston 23
located in the vicinity of the top dead center position (in the
compression stroke) that receives a significant reaction force of
compression is reduced, which reduces the durability of the second
swash plate 51 and the second shoes 25B.
[0090] (2-8) As the rolling elements of the radial bearing 52A, the
rollers 52c are used. The roller bearing that uses the rollers 52c
as the rolling elements has superior load bearing properties as
compared to, for example, a case where balls are used as the
rolling elements. This reduces the size of the radial bearing 52A,
which reduces the size of the compressor 10.
[0091] (2-9) The race 55 is located between the rollers 53a of the
thrust bearing 53 and the first swash plate 18. The race 55 is
rotatable relative to the first swash plate 18.
[0092] In a case of a configuration in which, for example, the
rollers 53a of the thrust bearing 53 roll directly on the first
swash plate 18, a significant reaction force of compression is
concentrated on part of the first swash plate 18 (part of the first
swash plate 18 corresponding to the piston 23 located in the
vicinity of the top dead center position), which may cause partial
wear and deterioration. However, in the second embodiment, since
the race 55 is provided between the rollers 53a and the first swash
plate 18, the reaction force of compression applied to the rollers
53a is applied to the first swash plate 18 with reduced contact
pressure via the race 55. Therefore, the first swash plate 18 is
suppressed from being partially worn and deteriorated. Also, as for
the race 55 that rotates relative to the first swash plate 18, the
section to which a significant reaction force of compression is
applied via the rollers 53a is sequentially changed. This prevents
the race 55 from being partially worn and deteriorated.
[0093] (2-10) The engaging portion 18d is provided on the outer
circumferential portion 18-1 of the first swash plate 18 and
extends toward the second swash plate 51. The race 55 is engaged
with the first swash plate 18 by abutting against the engaging
portion 18d at the radially outward edge of the race 55.
[0094] For example, in a configuration in which the engaging
portion is provided at the inner circumferential portion of the
first swash plate 18 and the race 55 is engaged with the first
swash plate 18 at the radially inward edge, when lubricant
(refrigerant oil) that is adhered to the first swash plate 18 moves
radially outward by centrifugal force, the engaging portion hinders
the lubricant from entering between the first swash plate 18 and
the race 55. However, the second embodiment in which the race 55 is
engaged with the first swash plate 18 at the radially outward edge
prevents the engaging portion 18d from hindering the lubricant from
entering between the first swash plate 18 and the race 55. Thus,
the first swash plate 18 reliably slides with respect to the race
55.
[0095] (2-11) The engaging portion 18d has an annular shape.
Therefore, the engaging portion 18d is stably engaged with the race
55. Thus, the race 55 further reliably slides with respect to the
first swash plate 18.
[0096] Next, a third embodiment of the present invention will be
described with reference to FIG. 5. In the third embodiment, only
differences from the second embodiment are explained. Like or the
same members are given the like or the same numbers and detailed
explanations are omitted.
[0097] In the third embodiment, the support portion 39 is not
decentered from the axis M1 of the first swash plate 18. That is,
the second swash plate 51, the radial bearing 52A (see FIG. 3), and
the thrust bearing 53 (including the race 55) are not decentered
from the first swash plate 18. In this case, as for part of the
outer circumferential edge of the first swash plate 18 that
corresponds to the piston 23B located at the bottom dead center
position, the salient corner 18c need not be chamfered as shown in
FIG. 5 because the salient corner 18c toward the second swash plate
51 does not significantly project in the radial direction from the
second swash plate 51.
[0098] Furthermore, in the third embodiment, the PCD of the thrust
bearing 53 is greater than the diameter of an imaginary cylinder
defined about the axes M1, M2 of the first swash plate 18 and the
second swash plate 51 and passes through the center points P of the
first shoe 25A and the second shoe 25B. In this manner, the thrust
bearing 53 (the rollers 53a) receives the reaction force of
compression transmitted through the second swash plate 51 in a
suitable manner, which improves the durability. The "PCD" of the
thrust bearing 53 refers to the diameter of an imaginary cylinder
having the axis at the center of the thrust bearing 53 (at the axes
M1, M2 of the first swash plate 18 and the second swash plate 51)
and passes through the mid point of the rotating axis of the
rollers 53a.
[0099] Next, a fourth embodiment of the present invention will be
described with reference to FIGS. 6 to 8. In the fourth embodiment,
only differences from the first and second embodiments are
explained. Like or the same members are given the like or the same
numbers and detailed explanations are omitted.
[0100] The rotor 17 is fixed to the drive shaft 16, and a swash
plate 58 is supported on the drive shaft 16. The swash plate 58 is
permitted to slide along and incline with respect to the drive
shaft. Coupling pieces 59, 60 are fixed to the swash plate 58, and
guide pins 61, 62 are fixed to the coupling pieces 59, 60. A pair
of guide holes 171 (only one is shown) is formed in the rotor 17.
Head portions of the guide pins 61, 62 are slidably fitted to the
guide holes 171. The engagement of the guide holes 171 with the
guide pins 61, 62 allows the swash plate 58 to incline with respect
to the axial direction of the drive shaft 16 and rotate integrally
with the drive shaft 16. The inclination of the swash plate 58 is
guided by the guide holes 171 and the guide pins 61, 62, and the
drive shaft 16. The coupling pieces 59, 60, the guide pins 61, 62,
and the guide holes 171 form a hinge mechanism 19A.
[0101] The swash plate 58 shown by a solid line in FIG. 6 is in the
maximum inclination state of the swash plate 58. When the center of
the swash plate 58 moves toward the cylinder block 11, the
inclination of the swash plate 58 decreases. The swash plate 58
shown by a chain line in FIG. 6 is in the minimum inclination
state.
[0102] Part of the outer circumferential edge portion of the swash
plate 58 corresponding to the piston 23A located at the top dead
center position and circumferentially adjacent parts thereof are
provided with an inclined surface on a salient corner 58a opposite
to the piston 23. That is, part of the outer circumferential edge
portion of the swash plate 58 corresponding to the vicinity of the
hinge mechanism 19A is provided with the inclined surface on the
salient corner 58a toward the hinge mechanism 19A. In other words,
part of the outer circumferential edge portion of the swash plate
58 corresponding to a circumferential range of the swash plate 58
that arranges the piston 23A at the top dead center position is
provided with the inclined surface on the salient corner 58a
opposite to the piston 23. As shown in FIG. 7, part of the inclined
surface of the salient corner 58a corresponding to the piston 23
located at the top dead center position is the largest, and
gradually becomes smaller along the circumferential direction.
[0103] As shown in FIG. 8, when the swash plate 58 is in the
maximum inclination state, the inclined surface provided on the
salient corner 58a is located on the circumferential surface of an
imaginary cylinder C having an axis M3 that is parallel to the axis
L of the drive shaft 16. In the example shown in FIG. 8, the axis
M3 is displaced with respect to the axis L from the piston 23A
located at the top dead center position toward the drive shaft 16.
The diameter of the imaginary cylinder C is greater than or equal
to the diameter of the swash plate 58.
[0104] At the outer circumferential edge portion of the swash plate
58 that corresponds to the piston 23A located at the top dead
center position, the salient corner 58a opposite to the piston 23
significantly projects in the radial direction of the drive shaft
16 when the swash plate 58 tilts with respect to the drive shaft
16. Therefore, providing the inclined surface at the projecting
portion (part of the salient corner 58a) of the swash plate 58
permits the swash plate 58 to be enlarged while suppressing
reduction in the durability and enlargement of the pistons 23.
Therefore, a significant reaction force of compression applied to
the swash plate 58 is received in a suitable manner via the second
shoe 25B of the piston 23 located in the vicinity of the top dead
center position. This improves the durability of the swash plate
58.
[0105] It should be understood that the invention may be embodied
in the following forms without departing from the spirit or scope
of the invention.
[0106] (1) In the first embodiment, the radial bearing 52 may be
omitted, and the second swash plate 51 may slide with respect to
the support portion 39.
[0107] (2) In the first embodiment, the thrust bearing 53 may be
omitted, and the second swash plate 51 may directly slide with
respect to the first swash plate 18.
[0108] (3) In the first embodiment, the radial bearing 52 and the
thrust bearing 53 may be omitted, and the second swash plate 51 may
be secured to the first swash plate 18 so that the second swash
plate 51 rotates integrally with the first swash plate 18.
[0109] In this case, part of the outer circumferential edge portion
of the second swash plate 51 corresponding to the piston 23A
located at the top dead center position is provided with an
inclined surface (a chamfer) on the salient corner toward the first
swash plate 18. In addition, part of the outer circumferential edge
portion of the second swash plate 51 corresponding to the piston
23B located at the bottom dead center position is provided with an
inclined surface (a chamfer) on the salient corner opposite to the
first swash plate 18.
[0110] With reference to FIG. 2, when the second swash plate 51
inclines with respect to the drive shaft 16, the salient corner
toward the first swash plate 18 significantly projects in the
radial direction of the drive shaft 16 at the outer circumferential
edge portion of the second swash plate 51 that corresponds to the
piston 23A located at the top dead center position. Also, at the
outer circumferential edge portion of the second swash plate 51
corresponding to the piston 23B located at the bottom dead center
position, the salient corner opposite to the first swash plate 18
significantly projects in the radial direction of the drive shaft
16. Therefore, providing the inclined surfaces (the chamfers) at
the projecting portions (part of the salient corners) of the second
swash plate 51 permits the second swash plate 51 to be enlarged
while suppressing reduction in the durability and enlargement of
the pistons 23. Therefore, the contact area between the second shoe
25B of the piston 23 located in the vicinity of the top dead center
position and the second swash plate 51 can further be increased,
which further improves the durability of the second swash plate 51
and the second shoe 25B.
[0111] (4) In the first embodiment, two swash plates, which are the
first swash plate 18 and the second swash plate 51, are used.
However, for example, a third swash plate may be arranged between
the second swash plate 51 and the second shoes 25B. That is, the
swash plate configuration to which the present invention may be
applied is not limited to the one that uses the first swash plate
and the second swash plate, but the swash plate configuration may
include a number of swash plates such as three, four, or five swash
plates.
[0112] (5) The present invention may be applied to a variable
displacement swash plate type compressor including double head
pistons. In this case, the second swash plate may be arranged on
either the front or rear surfaces of the first swash plate, or may
be arranged on each of the front and rear surfaces of the first
swash plate.
[0113] (6) The present invention need not be applied to the
refrigerant compressor of the refrigeration circuit, but may be
applied to, for example, an air-compressor.
[0114] (7) The second embodiment may be modified such that, for
example, the sliding surface 25b of each first shoe 25A is flat as
shown in FIG. 5.
[0115] (8) The second embodiment may be modified such that, for
example, the sliding surface 25b of each second shoe 25B is dented
at the center as shown in FIG. 5. In this case, the weight of each
second shoe 25B, which reciprocate with the associated piston 23,
is reduced, which reduces the inertial force of the second shoe
25B. Therefore, the inclination angle of the first swash plate 18
and the second swash plate 51, that is, the displacement of the
compressor is smoothly changed.
[0116] (9) In the second and third embodiments, the thrust bearing
53 may be changed to a roller bearing, which includes balls as the
rolling elements.
[0117] (10) In the second and third embodiments, the thrust bearing
53 may be changed to a sliding bearing.
[0118] (11) In the second and third embodiments, the radial bearing
52A only receives a radial load (a load perpendicular to the axis
M2) applied to the second swash plate 51. Instead, for example, the
rollers 52c may be tilted with respect to the axis M2 of the second
swash plate 51 such that the radial bearing 52A also receives a
thrust load (a load along the axis M2) in addition to the radial
load.
[0119] (12) In the second and third embodiments, the thrust bearing
53 only receives the thrust load applied to the second swash plate
51. Instead, for example, the rollers 53a may be tilted with
respect to the surface of the second swash plate 51 such that the
thrust bearing 53 also receives the radial load in addition to the
thrust load.
[0120] (13) In the second and third embodiments, the race 55 may be
omitted, and the rollers 53a of the thrust bearing 53 may roll
directly on the first swash plate 18.
[0121] (14) In the second and third embodiments, the engaging
portion 18d may be omitted, and an engaging portion may be provided
on the inner circumferential portion of the first swash plate 18
(for example, the proximal portion of the support portion 39 may
serve also as the engaging portion) so that the race 55 is engaged
with the first swash plate 18 on at radially inward edge.
* * * * *