U.S. patent application number 15/442064 was filed with the patent office on 2017-10-05 for double- headed piston type swash plate compressor.
This patent application is currently assigned to KABUSHIKI KAISHA TOYOTA JIDOSHOKKI. The applicant listed for this patent is KABUSHIKI KAISHA TOYOTA JIDOSHOKKI. Invention is credited to Hiroyuki NAKAIMA, Hiromichi OGAWA, Takahiro SUZUKI, Shinya YAMAMOTO.
Application Number | 20170284381 15/442064 |
Document ID | / |
Family ID | 59886016 |
Filed Date | 2017-10-05 |
United States Patent
Application |
20170284381 |
Kind Code |
A1 |
OGAWA; Hiromichi ; et
al. |
October 5, 2017 |
DOUBLE- HEADED PISTON TYPE SWASH PLATE COMPRESSOR
Abstract
A double-headed piston type swash plate compressor includes a
rotation shaft, a housing, a swash plate, two cylinder bores, a
double-headed piston, and two shoes. The double-headed piston
includes two shoe holders, a neck, two heads, and two coupling
portions. At least one of the two coupling portions includes a load
receiving portion. The load receiving portion is configured to
receive bending load that is applied from the swash plate to the
double-headed piston and acts toward an inner side in the radial
direction. The load receiving portion is separated from the wall
surface of the cylinder bore when load applied to the double-headed
piston is less than a specific threshold value. The load receiving
portion abuts against the inner wall of the cylinder bore and
receives the bending load when the load applied to the
double-headed piston is greater than the specific threshold
value.
Inventors: |
OGAWA; Hiromichi;
(Kariya-shi, JP) ; YAMAMOTO; Shinya; (Kariya-shi,
JP) ; NAKAIMA; Hiroyuki; (Kariya-shi, JP) ;
SUZUKI; Takahiro; (Kariya-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KABUSHIKI KAISHA TOYOTA JIDOSHOKKI |
Aichi-ken |
|
JP |
|
|
Assignee: |
KABUSHIKI KAISHA TOYOTA
JIDOSHOKKI
Aichi-ken
JP
|
Family ID: |
59886016 |
Appl. No.: |
15/442064 |
Filed: |
February 24, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04B 1/295 20130101;
F04B 27/18 20130101; F04B 39/0005 20130101; F04B 49/125 20130101;
F04B 1/29 20130101; F04B 27/1045 20130101; F04B 27/1036 20130101;
F04B 27/0878 20130101 |
International
Class: |
F04B 1/12 20060101
F04B001/12; F04B 49/12 20060101 F04B049/12; F04B 1/14 20060101
F04B001/14; F04B 1/16 20060101 F04B001/16; F04B 1/02 20060101
F04B001/02; F04B 1/29 20060101 F04B001/29 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 30, 2016 |
JP |
2016-068655 |
Claims
1. A double-headed piston type swash plate compressor comprising: a
rotation shaft extending in an axial direction and a radial
direction; a housing that accommodates the rotation shaft; a swash
plate that rotates when the rotation shaft rotates; two cylinder
bores located in the housing at an outer side of the rotation shaft
in the radial direction; a double-headed piston that reciprocates
in the two cylinder bores; and two shoes that couple the
double-headed piston to the swash plate, wherein the two cylinder
bores and the double-headed piston define two compression chambers,
rotation of the swash plate reciprocates the double-headed piston
in the two cylinder bores and compresses fluid in each of the
compression chambers, the double-headed piston includes: two shoe
holders that hold the two shoes, wherein the two shoe holders are
opposed to each other in an axial direction of the double-headed
piston; a neck that couples the two shoe holders, wherein the neck
is located at an outer circumferential side of the swash plate and
deformable in the radial direction; two heads respectively located
at two ends of the double-headed piston in the axial direction of
the double-headed piston, wherein each of the two heads includes a
side surface opposing a wall surface of the cylinder bore; and two
coupling portions that couple the two shoe holders and the two
heads, respectively, at least one of the two coupling portions
includes a load receiving portion located between the corresponding
head and the corresponding shoe holder as viewed in the radial
direction, wherein the load receiving portion is configured to
receive bending load that is applied from the swash plate to the
double-headed piston and acts toward an inner side in the radial
direction, the load receiving portion is separated from the wall
surface of the cylinder bore when load applied to the double-headed
piston is less than a specific threshold value, and the load
receiving portion abuts against the inner wall of the cylinder bore
and receives the bending load when the load applied to the
double-headed piston is greater than the specific threshold
value.
2. The double-headed piston type swash plate compressor according
to claim 1, wherein each of the two coupling portions includes: an
outer portion extending in the axial direction of the double-headed
piston; and an inner portion located at the inner side of the outer
portion in the radial direction and extended from the head in the
axial direction of the double-headed piston, the inner portion
includes an inner surface opposing the wall surface of the cylinder
bore in the radial direction, the inner surface and the side
surface of the head form a step so that the inner surface is
farther from the wall surface of the cylinder bore than the side
surface of the head, and the load receiving portion is an end of
the inner portion near the corresponding shoe holder.
3. The double-headed piston type swash plate compressor according
to claim 2, when referring to a direction orthogonal to both of the
axial direction and an opposing direction of the inner portion and
the outer portion as a widthwise direction, the inner portion
includes a fixed-width portion having a fixed width, and the end of
the inner portion near the corresponding shoe holder is wider than
the fixed-width portion.
4. The double-headed piston type swash plate compressor according
to claim 1, wherein the cylinder bore includes oil and an oil
collection region located between the load receiving portion and
the corresponding head; and the oil enters the oil collection
region when load applied to the double-headed piston is greater
than the threshold value.
5. The double-headed piston type swash plate compressor according
to claim 1, each of the two coupling portions includes the load
receiving portion, when the double-headed piston reciprocates from
a first position to a second position, a first one of the load
receiving portions that is included in a first one of the two
coupling portions opposes the wall surface of the cylinder bore
when the double-headed piston is located at the first position, and
a second one of the load receiving portions that is included in a
second one of the two coupling portions opposes the wall surface of
the cylinder bore when the double-headed piston is located at the
second position.
6. The double-headed piston type swash plate compressor according
to claim 1, further comprising an actuator that changes an
inclination angle of the swash plate, wherein the actuator
includes: a movable body that is movable in the axial direction of
the rotation shaft; and a partition that defines a control chamber
in cooperation with the movable body, and the actuator is operable
to change an inclination angle of the swash plate when the movable
body is moved in accordance with pressure of the control
chamber.
7. The double-headed piston type swash plate compressor according
to claim 6, wherein the two heads include a first head and a second
head, and the second head has a smaller diameter than a diameter of
the first head.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a double-headed piston type
swash plate compressor.
[0002] One example of a compressor is a double-headed piston type
swash plate compressor including a swash plate that rotates when a
rotation shaft rotates and a double-headed piston that reciprocates
in a pair of cylinder bores when the swash plate rotates. The
double-headed piston compresses fluid in compression chambers that
are defined in the two cylinder bores when the double-headed piston
reciprocates (refer to Japanese Laid-Open Patent Publication No.
2015-161173). The double-headed piston type swash plate compressor
compresses fluid that is subject to compression when the
double-headed piston reciprocates.
[0003] In the structure of the double-headed piston type swash
plate compressor, the fluid, which is subject to compression, and
the swash plate apply load to the double-headed piston. Load
includes bending load that acts toward the inner side in the radial
direction of the rotation shaft. Thus, the double-headed piston
requires strength that counters the bending load. Abutment of the
double-headed piston against an inner wall of the cylinder bore may
be increased to increase the strength of the piston. However, this
will increase power loss and is not desirable.
SUMMARY OF THE INVENTION
[0004] It is an object of the present invention to provide a
double-headed piston type swash plate compressor that receives
bending load applied to a double-headed piston.
[0005] To achieve the above object, a double-headed piston type
swash plate compressor according to one aspect of the present
invention includes a rotation shaft, a housing, a swash plate, two
cylinder bores, a double-headed piston, and two shoes. The rotation
shaft extends in an axial direction and a radial direction. The
housing accommodates the rotation shaft. The swash plate rotates
when the rotation shaft rotates. The two cylinder bores are located
in the housing at an outer side of the rotation shaft in the radial
direction. The double-headed piston reciprocates in the two
cylinder bores. The two shoes couple the double-headed piston to
the swash plate. The two cylinder bores and the double-headed
piston define two compression chambers. Rotation of the swash plate
reciprocates the double-headed piston in the two cylinder bores and
compresses fluid in each of the compression chambers. The
double-headed piston includes two shoe holders, a neck, two heads,
and two coupling portions. The two shoe holders hold the two shoes.
The two shoe holders are opposed to each other in an axial
direction of the double-headed piston. The neck couples the two
shoe holders. The neck is located at an outer circumferential side
of the swash plate and deformable in the radial direction. The two
heads are respectively located at two ends of the double-headed
piston in the axial direction of the double-headed piston. Each of
the two heads includes a side surface opposing a wall surface of
the cylinder bore. Two coupling portions couple the two shoe
holders and the two heads, respectively. At least one of the two
coupling portions includes a load receiving portion located between
the corresponding head and the corresponding shoe holder as viewed
in the radial direction. The load receiving portion is configured
to receive bending load that is applied from the swash plate to the
double-headed piston and acts toward an inner side in the radial
direction. The load receiving portion is separated from the wall
surface of the cylinder bore when load applied to the double-headed
piston is less than a specific threshold value. The load receiving
portion abuts against the inner wall of the cylinder bore and
receives the bending load when the load applied to the
double-headed piston is greater than the specific threshold
value.
[0006] Other aspects and advantages of the present invention will
become apparent from the following description, taken in
conjunction with the accompanying drawings, illustrating by way of
example the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The invention, together with objects and advantages thereof,
may best be understood by reference to the following description of
the presently preferred embodiments together with the accompanying
drawings in which:
[0008] FIG. 1 is a cross-sectional view schematically showing a
double-headed piston type swash plate compressor;
[0009] FIG. 2 is a perspective view of a double-headed piston shown
in FIG. 1;
[0010] FIG. 3 is a perspective view of the double-headed piston
shown in FIG. 1;
[0011] FIG. 4 is a plan view of the double-headed piston shown in
FIG. 1 as viewed from a radially inner side;
[0012] FIG. 5 is an enlarged view schematically showing the
double-headed piston shown in FIG. 1 and the surrounding of the
double-headed piston during a low-load period;
[0013] FIG. 6 is an enlarged view schematically showing the
double-headed piston shown in FIG. 1 and the surrounding of the
double-headed piston during a high-load period; and
[0014] FIG. 7 is an enlarged view schematically showing the
double-headed piston shown in FIG. 1 and the surrounding of the
double-headed piston during the high-load period.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] One embodiment of the present invention will now be
described with reference to FIGS. 1 to 7. The double-headed piston
type swash plate compressor of the present embodiment is installed
in a vehicle for use with a vehicle air conditioner. That is, fluid
that is subject to compression by the double-headed piston type
swash plate compressor of the present embodiment is refrigerant
containing oil (lubricant). In FIGS. 1 and 5 to 7, the
double-headed piston 100 is shown in a side view. In FIG. 5, the
double-headed piston 100 is shown in a side view and a partially
enlarged view.
[0016] As shown in FIG. 1, a double-headed piston type swash plate
compressor 10 (hereinafter referred to as compressor 10) includes a
housing 11 that forms the shell of the compressor 10. The entire
housing 11 is tubular.
[0017] The housing 11 rotationally accommodates a rotation shaft
20. The rotation shaft 20 is located near the center in the housing
11. The axial direction Z of the rotation shaft 20 corresponds to
the axial direction of the housing 11. In the following
description, the axial direction Z of the rotation shaft 20 is
referred to as the axial direction Z.
[0018] The housing 11 includes a tubular front housing 12, which
forms one end of the housing 11 in the axial direction Z, a tubular
rear housing 13, which has a bottom and forms the other end of the
housing 11 in the axial direction Z, and two cylinder blocks 14 and
15 (first cylinder block 14 and second cylinder block 15), which
are arranged between the front housing 12 and the rear housing 13.
The cylinder blocks 14 and 15 are cylindrical and respectively
include first and second shaft holes 21 and 22 through which the
rotation shaft 20 can be inserted.
[0019] The first cylinder block 14 includes the first shaft hole 21
that extends through the first cylinder block 14 in the axial
direction Z. The first shaft hole 21 includes a first small
diameter hole 21a, which has a slightly larger diameter than the
rotation shaft 20, and a first large diameter hole 21b, which is
larger than the first small diameter hole 21a. The first small
diameter hole 21a is located closer to the front housing 12 than
the first large diameter hole 21b.
[0020] The second cylinder block 15 includes the second shaft hole
22 that extends through the second cylinder block 15 in the axial
direction Z. The second shaft hole 22 includes a second small
diameter hole 22a, which has a slightly larger diameter than the
rotation shaft 20, and a second large diameter hole 22b, which is
larger than the second small diameter hole 22a. The second small
diameter hole 22a is located closer to the rear housing 13 than the
second large diameter hole 22b. The two cylinder blocks 14 and 15
are coupled to each other with the two shaft holes 21 and 22 (more
specifically, two large diameter holes 21b and 22b) opposing each
other in the axial direction Z.
[0021] A first valve/port body 23 is arranged between the front
housing 12 and the first cylinder block 14. A second valve/port
body 24 is arranged between the rear housing 13 and the second
cylinder block 15. The valve/port bodies 23 and 24 each have the
form of a flat ring. The valve/port bodies 23 and 24 have a larger
inner diameter than the rotation shaft 20.
[0022] The rotation shaft 20 is inserted through the two shaft
holes 21 and 22 and the two valve/port bodies 23 and 24 and
extended from the front housing 12 to the rear housing 13. In this
case, one end of the rotation shaft 20 in the axial direction Z is
located in the front housing 12, and the other end of the rotation
shaft 20 in the axial direction Z is located in a regulation
chamber A1, which is defined by the rear housing 13 and the second
cylinder block 15. That is, the rotation shaft 20 extends through
the two cylinder blocks 14 and 15. The regulation chamber A1 will
be described later.
[0023] As shown in FIG. 1, a first radial bearing 31 that
rotationally supports the rotation shaft 20 is arranged between the
rotation shaft 20 and a wall surface of the first small diameter
hole 21a. In the same manner, a second radial bearing 41 that
rotationally supports the rotation shaft 20 is arranged between the
rotation shaft 20 and a wall surface of the second small diameter
hole 22a. The rotation shaft 20 is supported by the two radial
bearings 31 and 41 in the housing 11 in a rotatable manner.
[0024] The rotation shaft 20 includes a first shaft projection 20a
and a second shaft projection 20b. The first shaft projection 20a
is located in the first large diameter hole 21b and projected in
the radial direction R of the rotation shaft 20 (hereinafter
referred to as the radial direction R), and the second shaft
projection 20b is located in the second large diameter hole 22b and
projected in the radial direction R. The first shaft projection 20a
is opposed to a ring-shaped step surface in the axial direction X.
The step surface connects the first small diameter hole 21a to the
first large diameter hole 21b. A first thrust bearing 32 is
arranged between the first shaft projection 20a and the step
surface. The second shaft projection 20b is opposed to a
ring-shaped step surface in the axial direction X. The step surface
connects the second small diameter hole 22a to the second large
diameter hole 22b. A second thrust bearing 42 is arranged between
the second shaft projection 20b and the step surface.
[0025] The housing 11 includes two suction chambers 33 and 43
(first suction chamber 33 and second suction chamber 43) and two
discharge chambers 34 and 44 (first discharge chamber 34 and second
discharge chamber 44). Each of the first suction chamber 33 and the
first discharge chamber 34 is defined by the front housing 12 and
the first valve/port body 23. Each of the second suction chamber 43
and the second discharge chamber 44 is defined by the rear housing
13 and the second valve/port body 24. The two suction chambers 33
and 43 oppose each other in the axial direction Z, and the two
discharge chambers 34 and 44 oppose each other in the axial
direction Z. The suction chambers 33 and 43 and the discharge
chambers 34 and 44 are formed to be annular as viewed in the axial
direction Z, and the discharge chambers 34 and 44 are located at
the outer sides of the suction chambers 33 and 43.
[0026] As shown in FIG. 1, the compressor 10 includes a swash plate
50 that rotates when the rotation shaft 20 rotates. The swash plate
50 is inclined with respect to a direction that is orthogonal to
the axial direction Z of the rotation shaft 20.
[0027] The swash plate 50 includes a swash plate body 52, which has
the form of a flat ring. The swash plate body 52 includes a swash
plate insertion hole 51 through which the rotation shaft 20 is
inserted. The swash plate body 52 includes a first inclined surface
52a, which is directed toward the first cylinder block 14, and a
second inclined surface 52b, which is directed toward the side
opposite to the first inclined surface 52a.
[0028] The swash plate 50 of the present embodiment is configured
so that the inclination angle can be changed with respect to the
direction orthogonal to the axial direction Z of the rotation shaft
20.
[0029] The housing 11 includes a swash plate chamber A2 that
accommodates the swash plate 50. The swash plate chamber A2 is
defined by the two cylinder blocks 14 and 15. The swash plate
chamber A2 is located between the two shaft holes 21 and 22 and is
in communication with the two shaft holes 21 and 22.
[0030] As shown in FIG. 1, a side wall of the second cylinder block
15 defining the swash plate chamber A2 includes a suction port 53.
Thus, the suction port 53 is in communication with the swash plate
chamber A2. Further, the housing 11 includes a suction passage 54
through which the swash plate chamber A2 is in communication with
the suction chambers 33 and 43. The suction passage 54 includes a
first suction passage 54a and a second suction passage 54b. The
first suction passage 54a extends through the first cylinder block
14 and the first valve/port body 23 in the axial direction Z and
allows communication between the swash plate chamber A2 and the
first suction chamber 33. The second suction passage 54b extends
through the second cylinder block 15 and the second valve/port body
24 in the axial direction Z and allows communication between the
swash plate chamber A2 and the second suction chamber 43. A
plurality of the suction passages 54a and 54b extend in the
circumferential direction around the shaft holes 21 and 22 in the
cylinder blocks 14 and 15.
[0031] In such a structure, fluid that is drawn from the suction
port 53 flows through the swash plate chamber A2 and the suction
passage 54 into the suction chambers 33 and 43. In this case, the
swash plate chamber A2 and the two large diameter holes 21b and 22b
that are in communication with the swash plate chamber A2 have the
same pressure as the fluid drawn from the suction port 53.
[0032] The housing 11 includes a discharge passage 55 that is in
communication with the two discharge chambers 34 and 44. The
discharge passage 55 is located at the outer side of the swash
plate chamber A2 and cylinder bores 91 and 92 (first and second
cylinder bores 91 and 92, described below) in the radial direction
R. The discharge passage 55 is in communication with a discharge
port 56, which is located in the housing 11 (more specifically,
side wall of second cylinder block 15). Fluid in the two discharge
chambers 34 and 44 is discharged out of the discharge port 56
through the discharge passage 55.
[0033] As shown in FIG. 1, the compressor 10 includes a link
mechanism 60 that allows the inclination angle of the swash plate
50 to change and links the swash plate 50 to the rotation shaft 20
so that the swash plate 50 and the rotation shaft 20 integrally
rotate. The link mechanism 60 is located closer to the front
housing 12 than the swash plate 50 except for part of the link
mechanism 60.
[0034] The link mechanism 60 includes a lug arm 61, a first link
pin 62, and a second link pin 63. The lug arm 61 extends from the
first large diameter hole 21b to the swash plate chamber A2. The
first link pin 62 pivotally couples the lug arm 61 to the swash
plate 50. The second link pin 63 pivotally couples the lug arm 61
to the rotation shaft 20.
[0035] The lug arm 61 is L-shaped and includes a basal portion
opposing the front housing 12 and a distal portion opposing the
swash plate 50. The distal portion of the lug arm 61 projects out
of the swash plate 50 toward the rear housing 13 through an arm
through hole 52c in the swash plate body 52 of the swash plate 50.
The projecting portion includes a weight.
[0036] The arm through hole 52c, for example, does not have an
annular shape extending over the entire circumference of the swash
plate 50 and is rectangular as viewed in the axial direction Z. The
arm through hole 52c includes an inner surface including two
opposing inner surfaces that are opposed to each other in the
direction orthogonal to both of the thickness-wise direction of the
swash plate 50 and the direction parallel to the axes of the swash
plate insertion hole 51 and the arm through hole 52c.
[0037] The first link pin 62 is, for example, cylindrical. The
first link pin 62 is located in the arm through hole 52c so that
the axial direction of the first link pin 62 corresponds to the
opposing direction of the two opposing inner surfaces. The first
link pin 62 is extended through a portion of the lug arm 61
extending in the axial direction Z and attached to the swash plate
50. The portion of the lug arm 61 extending in the axial direction
Z is supported by the swash plate 50 pivotally about the axis of
the first link pin 62, which serves as the first pivot center
M1.
[0038] The second link pin 63 is, for example, cylindrical. The
second link pin 63 is arranged so that the axial direction of the
second link pin 63 is parallel to the axial direction of the first
link pin 62. The second link pin 63 is located in the basal portion
of the lug arm 61 separated from where the lug arm 61 extends in
the axial direction Z. The second link pin 63 is extended through
the basal portion of the lug arm 61 and fixed to the rotation shaft
20. The basal portion of the lug arm 61 is pivotally supported by
the rotation shaft 20 about the axis of the second link pin 63,
which serves as the second pivot center M2.
[0039] As shown in FIG. 1, the compressor 10 includes an actuator
70 that changes the inclination angle of the swash plate 50. The
actuator 70 is located closer to the rear housing 13 than the swash
plate 50.
[0040] The actuator 70 includes a movable body 71 that is movable
in the axial direction Z, and a partition 72 that defines a control
chamber A3 in cooperation with the movable body 71, and two
coupling pieces 73 that couple the movable body 71 to the swash
plate 50. The compression chamber A3 is used to control the
inclination angle of the swash plate 50.
[0041] The movable body 71 has the form of a tube (more
specifically, cylindrical tube) and includes a bottom and a tubular
portion. The movable body opens toward one side. The bottom of the
movable body 71 includes an insertion hole through which the
rotation shaft 20 can be inserted. The movable body 71 rotates
integrally with the rotation shaft 20 with the rotation shaft 20
inserted through the insertion hole and the open end of the movable
body 71 directed toward the swash plate chamber A2.
[0042] The partition 72 has the form of a flat ring and has an
outer diameter that is set to be substantially the same as an inner
diameter of the movable body 71. The partition 72, which is fitted
onto the rotation shaft 20 and into the movable body 71, is fixed
to the rotation shaft 20 so that the partition 72 rotates
integrally with the rotation shaft 20. The partition 72 closes the
open end of the movable body 71 that is close to the swash plate
chamber A2. The control chamber A3 is defined by an inner
circumferential surface of the movable body 71 and a surface of the
partition 72 located at the side opposite to the swash plate
chamber A2.
[0043] A portion between the inner circumferential surface of the
movable body 71 and an outer circumferential surface of the
partition 72 is sealed to restrict movement of fluid between the
control chamber A3 and the swash plate chamber A2. This allows the
control chamber A3, the swash plate chamber A2, and the second
large diameter hole 22b to have different pressures. The position
of the movable body 71 changes in accordance with the pressure
difference of the control chamber A3 and the swash plate chamber
A2.
[0044] The rotation shaft 20 includes a shaft passage 74 that
allows communication between the regulation chamber A1 and the
control chamber A3. The shaft passage 74 includes an axial portion,
which opens in the regulation chamber A1 and extends in the axial
direction Z, and a radial portion, which is in communication with
the axial portion. The radial portion opens in the control chamber
A3 and extends in the radial direction R. The shaft passage 74
allows fluid to move between the control chamber A3 and the
regulation chamber A1. Thus, the control chamber A3 and the
regulation chamber A1 have the same pressure.
[0045] The compressor 10 includes a pressure controller 75 that
controls the pressure of the regulation chamber A1. The pressure
controller 75 includes a low-pressure passage that allows
communication between the second suction chamber 43 and the
regulation chamber A1, a high-pressure passage that allows
communication between the second discharge chamber 44 and the
regulation chamber A1, a valve that is located on the low-pressure
passage and regulates the amount of fluid discharged from the
regulation chamber A1 into the second suction chamber 43, and an
orifice that is located in the high-pressure passage and regulates
the flow rate of the discharged fluid flowing in the high-pressure
passage. The pressure controller 75 controls the pressure of the
regulation chamber A1 by controlling the valve. This allows the
position of the movable body 71 to be adjusted.
[0046] The two coupling pieces 73 project toward the swash plate 50
from part of the annular open end of the movable body 71 as viewed
in the axial direction Z. More specifically, the two coupling
pieces 73 project toward the swash plate 50 from a portion of the
movable body 71 located toward the side opposite to the distal
portion of the lug arm 61 from the rotation shaft 20 as viewed in
the axial direction Z. The two coupling pieces 73 oppose each other
in the pivot axes of the two pivot centers M1 and M2 (direction in
which pivot centers M1 and M2 extend).
[0047] The swash plate 50 includes a plate-shaped coupling
receiving portion 76 that projects from the second inclined surface
52b and overlaps the two coupling pieces 73 as viewed in the pivot
axis. The coupling receiving portion 76 and the arm through hole
52c are located in the second inclined surface 52b at opposite
sides of the swash plate insertion hole 51. The coupling receiving
portion 76 includes a coupling hole through which a coupling pin 77
extending in the pivot axis can be inserted. The coupling pin 77 is
located between the two coupling pieces 73. The coupling pin 77 is
inserted through the coupling hole and fixed to the two coupling
pieces 73. Thus, the swash plate 50 is coupled to the movable body
71. In this case, the movement of the movable body 71 changes the
inclination angle of the swash plate 50. That is, adjustment of the
position of the movable body 71 adjusts the inclination angle of
the swash plate 50.
[0048] To simplify the drawings, the coupling pin 77 and the
coupling hole have the same shape. However, the coupling hole
actually has an oval shape elongated in the vertical direction and
has a larger diameter than the coupling pin 77 so as to correspond
to changes in the inclination angle of the swash plate 50.
[0049] As shown in FIG. 1, the swash plate 50 includes a first
projection 81 that projects from the first inclined surface 52a and
a second projection 82 that projects from the second inclined
surface 52b. The second projection 82 is separate from the coupling
receiving portion 76.
[0050] The first projection 81 does not extend over the entire
circumference of the first inclined surface 52a. Rather, the first
projection 81 extends over a portion of the first inclined surface
52a located at the opposite side of the arm through hole 52c with
respect to the swash plate insertion hole 51. The second projection
82 extends in the circumferential direction around the swash plate
insertion hole 51 in the second inclined surface 52b. The two
projections 81 and 82 are located in the radial direction R at the
inner side of a portion of the inclined surfaces 52a and 52b that
is held by two shoes 121 and 122 (described later). Thus, the swash
plate 50 includes a circumferential portion that is thinner than
the portion where the two projections 81 and 82 and the coupling
receiving portion 76 are arranged.
[0051] A recovery spring 83 is fixed to the first shaft projection
20a of the rotation shaft 20. The recovery spring 83 extends in the
axial direction Z from the first shaft projection 20a toward the
swash plate chamber A2. Further, an inclination reduction spring 84
is arranged between the partition 72 and the swash plate 50. The
inclination reduction spring 84 includes one end fixed to the
partition 72 and the other end fixed to the swash plate 50. The
inclination reduction spring 84 biases the swash plate 50 in a
direction that decreases the inclination angle of the swash plate
50.
[0052] The compressor 10 includes pairs of cylinder bores 91 and
92. The cylinder bores 91 and 92 of each pair are opposed to each
other in the axial direction Z and located at the outer side of the
rotation shaft 20 in the radial direction R in the housing 11. The
cylinder bores 91 and 92 are located at the outer side of the shaft
holes 21 and 22 in the radial direction R. The pairs of the
cylinder bores 91 and 92 extend in the circumferential direction
around the shaft holes 21 and 22 of the cylinder blocks 14 and 15.
The cylinder bores 91 are opposed to the cylinder bores 92 at
opposite sides of the swash plate chamber A2. The cylinder bores 91
and 92 are coaxial.
[0053] To facilitate understanding, FIG. 1 shows only one of the
cylinder bores 91 and one of the cylinder bores 92. Further, the
cylinder bores 91 and 92 are separated from the suction passages
54a and 54b in the circumferential direction so that the cylinder
bores 91 and 92 do not interfere with the suction passages 54a and
54b around the shaft holes 21 and 22.
[0054] The cylinder bores 91 and 92 have the form of a tube (more
specifically, cylindrical tube) and extend through the
corresponding cylinder blocks 14 and 15 in the axial direction Z.
One opening of each of the cylinder bores 91 and 92 is in
communication with the swash plate chamber A2, and the other
opening of each of the cylinder bores 91 and 92 is closed by the
valve/port body 23 or 24. The first valve/port body 23 partitions
each first cylinder bore 91 from the first suction chamber 33 and
the first discharge chamber 34, and the second valve/port body 24
partitions each second cylinder bore 92 from the second suction
chamber 43 and the second discharge chamber 44.
[0055] As shown in FIG. 1, the valve/port bodies 23 and 24 close
the openings of the cylinder bores 91 and 92 and include suction
ports 23a and 24a that are respectively in communication with the
suction chambers 33 and 43 and discharge ports 23b and 24b, which
are respectively in communication with the discharge chambers 34
and 44 through the valve. The suction ports 23a and 24a and the
discharge ports 23b and 24b extend in the circumferential direction
in correspondence with the cylinder bores 91 and 92 that extend in
the circumferential direction.
[0056] As described above, refrigerant contains oil. Thus, oil
exists in a space where refrigerant exists, more specifically, in
the swash plate A2 and the cylinder bores 91 and 92 that are in
communication with the swash plate A2.
[0057] The compressor 10 includes the double-headed piston 100 that
reciprocates in each pair of the cylinder bores 91 and 92 and the
two shoes 121 and 122 that couple the double-headed piston 100 to
the swash plate 50.
[0058] The double-headed piston 100 is accommodated in each pair of
the cylinder bores 91 and 92 so that the axial direction of the
double-headed piston 100 corresponds to the axial direction Z of
the rotation shaft 20 (in other words, opposing direction of two
cylinder bores 91 and 92). More specifically, the double-headed
piston 100 is arranged in each pair of the cylinder bores 91 and 92
so that the double-headed piston 100 is coaxial with the two
cylinder bores 91 and 92.
[0059] The double-headed pistons 100 extend in the circumferential
direction in correspondence with the cylinder bores 91 and 92
extend in the circumferential direction. That is, each pair of the
cylinder bores 91 and 92 includes one of the double-headed pistons
100.
[0060] The structures of the double-headed piston 100 and the like
will now be described in detail.
[0061] As shown in FIGS. 2 to 5, the double-headed piston 100
includes a neck 101, shoe holders 102 and 112 that hold the two
shoes 121 and 122, two heads 103 and 113 located at the two ends in
the axial direction of the double-headed piston 100, and two
coupling portions 104 and 114 that respectively couple the shoe
holders 102 and 112 to the heads 103 and 113. The two shoe holders
102 and 112 oppose each other in the axial direction of the
double-headed piston 100. The neck 101 couples the two shoe holders
102 and 112.
[0062] The coupling portions 104 and 114 include inner portions 105
and 115 and outer portions 106 and 116 extending in the axial
direction of the double-headed piston 100. The inner portions 105
and 115 are respectively opposed to the outer portions 106 and 116
in the radial direction R. Further, the coupling portions 104 and
114 include plates 107 and 117 that couple the inner portions 105
and 115 to the outer portions 106 and 116, respectively. The inner
portions 105 and 115 are located at the inner side of the outer
portions 106 and 116 in the radial direction R (i.e., in portion of
double-headed piston 100 that is close to rotation shaft 20).
[0063] The axial direction of the double-headed piston 100 is the
direction in which the head 103 is opposed to the head 113, and the
radial direction R is the direction in which the inner portions 105
and 115 are opposed to the outer portions 106 and 116. To
facilitate understanding, a direction orthogonal to both of the
axial direction of the double-headed piston 100 and the opposing
direction of the inner portions 105 and 115 and the outer portions
106 and 116 is hereinafter referred to as the widthwise direction
W.
[0064] The coupling portions 104 and 114 of the present embodiment
are deformed more easily in the widthwise direction W than in the
radial direction R. More specifically, the coupling portions 104
and 114 are configured to have a smaller section modulus in the
widthwise direction W than in the radial direction R. Each of the
coupling portions 104 and 114 has a width that is less than or
equal to that of the neck 101.
[0065] As shown in FIG. 5, the two shoe holders 102 and 112 include
semi-spherical surfaces 102a and 112a. The semi-spherical surfaces
102a and 112a are recessed away from each other. The
circumferential portion of the swash plate 50 is arranged between
the shoe holders 102 and 112.
[0066] The first shoe 121 of the two shoes 121 and 122 is located
between the first inclined surface 52a of the swash plate 50 and
the first semi-spherical surface 102a of the first shoe holder 102,
and the second shoe 122 is located between the second inclined
surface 52b of the swash plate 50 and the second semi-spherical
surface 112a of the second shoe holder 112. The two shoes 121 and
122 are semi-spherical. The two shoes 121 and 122 include bottom
surfaces that abut against the circumferential portions of the
corresponding inclined surfaces 52a and 52b and spherical surfaces
that abut against the corresponding semi-spherical surfaces 102a
and 112a. The shoe holders 102 and 112 hold the two shoes 121 and
122 with the two shoes 121 and 122 holding the circumferential
portions of the swash plate 50. Thus, the two shoes 121 and 122
couple the double-headed piston 100 to the swash plate 50.
[0067] In such a structure, rotation of the swash plate 50 applies
load, including a component in the axial direction Z, to the
double-headed piston 100 through the two shoes 121 and 122. This
converts the rotation of the swash plate 50 into reciprocation of
the double-headed piston 100. In this case, the stroke of the
double-headed piston 100 changes in accordance with the inclination
angle of the swash plate 50.
[0068] The neck 101 is located at an outer circumferential side of
the swash plate 50, more specifically, at the outer side of the
swash plate 50 in the radial direction R. The neck 101 is larger in
the widthwise direction W than in the radial direction R so that
the neck 101 is deformable in the radial direction R. More
specifically, the neck 101 is plate-shaped, and the radial
direction R of the neck 101 refers to a thickness-wise direction.
The section modulus of the neck 101 is smaller in the radial
direction R than in the widthwise direction W. The two shoe holders
102 and 112 are located at the two ends of the inner surface of the
neck 101 in the axial direction of the double-headed piston
100.
[0069] In the present embodiment, the neck 101 has a width that is
equal to that of each of the shoe holders 102 and 112. However, the
neck 101 may have a width that is greater than that of each of the
shoe holders 102 and 112.
[0070] As shown in FIG. 3, the outer surface of the neck 101 is
curved in conformance with a wall surface 91a that is the wall
surface of the first cylinder bore 91. The outer surface of the
neck 101 includes neck recesses 101a that are recessed from the
outer surface of the neck 101 toward the inner side in the radial
direction R. The two neck recesses 101a are separated from each
other in the widthwise direction W. Thus, the two ends of the neck
101 in the widthwise direction are thinner than the central portion
of the neck 101 in the widthwise direction W and easily deformed in
the radial direction R.
[0071] As shown in FIGS. 2 to 5, each of the heads 103 and 113 is
tubular and has a bottom. The heads 103 and 113 include bottom
surfaces 103a and 113a, which have a slightly smaller diameter than
the first wall surfaces 91a of the first cylinder bore 91 and a
second wall surface 92a of the second cylinder bore 92 and side
surfaces 103b and 113b (i.e., outer circumferential surfaces 103b
and 113b), respectively. Further, the heads 103 and 113 open toward
the shoe holders 102 and 112.
[0072] As shown in FIG. 5, the first wall surface 91a of the first
cylinder bore 91 is opposed to the side surface 103b of the first
head 103, and a first gap 108 is formed between the first wall
surface 91a and the side surface 103b. The first head 103 is at
least partially accommodated in the first cylinder bore 91
regardless of where the double-headed piston 100 is located.
[0073] The first cylinder bore 91 includes a first compression
chambers A4 that is defined by the bottom surface 103a of the first
head 103, the first wall surfaces 91a, and the first valve/port
body 23. The first compression chamber A4 is in communication with
the first suction chamber 33 with the first suction ports 23a
located in between and is in communication with the first discharge
chamber 34 with the first discharge port 23b located in
between.
[0074] In the same manner, the second wall surface 92a of the
second cylinder bore 92 is opposed to the side surface 113b of the
second head 113, and a second gap 118 is formed between the second
wall surface 92a and the side surface 113b. The second head 113 is
at least partially accommodated in the second cylinder bore 92
regardless of where the double-headed piston 100 is located.
[0075] The second cylinder bore 92 includes a second compression
chambers A5 that is defined by the bottom surface 113a of the
second head 113, the second wall surfaces 92a, and the second
valve/port body 24. The second compression chamber A5 is in
communication with the second suction chamber 43 with the second
suction ports 24a located in between and is in communication with
the second discharge chamber 44 with the second discharge port 24b
located in between.
[0076] In such a structure, reciprocation of the double-headed
piston 100 draws fluid from the suction chambers 33 and 43 into the
compression chambers A4 and A5, where the fluid is compressed.
Then, the fluid is discharged into the discharge chambers 34 and
44. The stroke of the double-headed piston 100 changes in
accordance with the inclination angle of the swash plate 50 and
varies the displacement of the compressed fluid. That is, the
compressor 10 of the present embodiment is of a variable
displacement type.
[0077] As shown in FIG. 6, the position of the double-headed piston
100 where the inclination angle is the maximum and the first
compression chamber A4 is most compressed (i.e., position where
double-headed piston 100 is most proximate to first valve/port body
23) is referred to as the first position (top dead center of first
head 103 of double-headed piston 100). Further, as shown in FIG. 7,
the position of the double-headed piston 100 where the inclination
angle is the maximum and the second compression chamber A5 is most
compressed (i.e., position where double-headed piston 100 is most
proximate to second valve/port body 24) is referred to as the
second position (top dead center of second head 113 of
double-headed piston 100). The double-headed piston 100
reciprocates between the first position and the second position.
That is, the double-headed piston 100 can reciprocate from the
first position to the second position.
[0078] As shown in FIG. 5, the head 103 has a larger diameter than
the second head 113. The first cylinder bore 91 is larger than the
second cylinder bore 92 in correspondence with the difference in
diameter of the two heads 103 and 113. More specifically, the first
wall surface 91a has a larger diameter than the second wall surface
92a. Thus, the two gaps 108 and 118 have substantially the same
size (more specifically, same length in radial direction R).
[0079] The wall surfaces 91a and 92a of the two cylinder bores 91
and 92, which are coaxially opposed to each other have different
diameters. Thus, the outer portion of the first wall surface 91a in
the radial direction R is located outward in the radial direction R
from the outer side of the second wall surface 92a in the radial
direction R. As shown in FIG. 6, the outer portion of the first
wall surface 91a in the radial direction R is flush with a side
wall inner surface 15a that is an inner surface of the side wall of
the second cylinder block 15 that defines the swash plate chamber
A2. The side wall inner surface 15a and the second wall surface 92a
form a step.
[0080] As shown in FIGS. 3 and 5, the first outer portion 106
extends in the axial direction of the double-headed piston 100 from
the outer portion of the first head 103 in the radial direction R
and couples the first head 103 to the first shoe holder 102 with
the neck 101. More specifically, the first outer portion 106
connects the end of the neck 101 where the first shoe holder 102 is
arranged to the outer portion of the first head 103 in the radial
direction R. The first outer portion 106 is a plate having a width
in the widthwise direction W and a thickness in the radial
direction R. The first outer portion 106 includes an outer surface
curved in conformance with the first wall surface 91a.
[0081] The first outer portion 106 has a width that is less than or
equal to that of the neck 101. Further, the first outer portion 106
is at least partially narrower than the two shoe holders 102 and
112. In the present embodiment, the portion of the first outer
portion 106 excluding the longitudinal ends of the first outer
portion 106 is narrower than the two shoe holders 102 and 112.
[0082] The first inner portion 105 extends in the axial direction
of the double-headed piston 100 from the inner portion of the first
head 103 in the radial direction R. The first inner portion 105
includes a first basal portion 105a located near the first head 103
and a first distal portion 105b located near the first shoe holder
102. The first distal portion 105b of the first inner portion 105
is located between the first head 103 and the first shoe holder 102
as viewed in the radial direction R, more specifically, located at
the portion of the first coupling portion 104 closer to the first
shoe holder 102 than the first head 103. The first distal portion
105b corresponds to "an end of the inner portion near the shoe
holder."
[0083] As shown in FIG. 4, the first inner portion 105 is a plate
having a width in the widthwise direction W and a thickness in the
radial direction R. The first inner portion 105 includes a first
fixed-width portion 105c having a fixed width. The first
fixed-width portion 105c is located between the two ends 105a and
105b. In the present embodiment, the first fixed-width portion 105c
has a width that is less than that of each of the two shoe holders
102 and 112. The first distal portion 105b of the first inner
portion 105 is wider than the first fixed-width portion 105c.
[0084] As shown in FIG. 5, the first inner portion 105 is located
further inward from the side surface 103b of the first head 103.
Thus, the first distal portion 105b of the first inner portion 105
is located further inward from the side surface 103b of the first
head 103.
[0085] The first inner portion 105 includes a first inner surface
105d opposing the first wall surface 91a in the radial direction R.
The first inner surface 105d is curved in conformance with the
first wall surface 91a. The first inner surface 105d is farther
from the portion of the first wall surface 91a opposing the first
inner surface 105d than the side surface 103b of the first head
103. That is, the side surface 103b of the first head 103 and the
first inner surface 105d form a step so that the first inner
surface 105d is farther from the first wall surface 91a than the
side surface 103b of the first head 103.
[0086] The step may include, for example, a surface orthogonal to
the axial direction of the double-headed piston 100 as shown in
FIG. 5. Instead, the step may be, for example, tapered so that the
outer diameter gradually decreases from the first head 103 toward
the first shoe holder 102.
[0087] The step between the side surface 103b of the first head 103
and the first inner surface 105d may have any dimension, for
example, less than or equal to 1 mm (excluding 0 mm). In each of
the drawings, to facilitate understanding, the step is larger than
the actual one. Further, the first distal portion 105b has an edge
that is obliquely cut. Thus, the edge of the first inner surface
105d near the first distal portion 105b is inclined.
[0088] The first inner portion 105 is located at the inner side of
the first shoe holder 102 in the radial direction R. Thus, the
first distal portion 105b of the first inner portion 105 and the
first shoe holder 102 form a step as viewed in the widthwise
direction W.
[0089] The first coupling portion 104 includes a first rib 109 that
connects the first shoe holder 102 and the first distal portion
105b of the first inner portion 105, which form a step. The first
rib 109 connects the first distal portion 105b of the first inner
portion 105 to the first shoe holder 102 so that a first space A11
is defined by the side of the first distal portion 105b of the
first inner portion 105 as viewed in the widthwise direction W.
More specifically, the first rib 109 is inclined as viewed in the
widthwise direction W. As shown in FIG. 4, the length X11 of the
first inner portion 105 in the axial direction of the double-headed
piston 100 is greater than the length X12 of the first rib 109.
[0090] As shown in FIGS. 2 to 5, the thickness-wise direction of
the first plate 107 in the first coupling portion 104 is the
widthwise direction W. That is, the first plate 107 has a thickness
in the widthwise direction W. The thickness of the first plate 107
is smaller than the widths of the first inner portion 105 and the
first outer portion 106. The first plate 107 includes a first
through hole 107a extending in the widthwise direction W. The first
through hole 107a is, for example, defined by a wall recessed
toward the first shoe holder 102 as viewed in the widthwise
direction W and is in communication with the interior of the first
head 103, which is tubular and has a bottom.
[0091] The second coupling portion 114 is basically the same as the
first coupling portion 104 except that, for example, the second
coupling portion 114 in the axial direction of the double-headed
piston 100 is longer than the first coupling portion 104.
[0092] More specifically, as shown in FIGS. 3 and 5, the second
outer portion 116 extends in the axial direction of the
double-headed piston 100 from the outer portion of the second head
113 in the radial direction R and couples the second head 113 to
the second shoe holder 112 with the neck 101. The second outer
portion 116 includes an outer surface curved in conformance with
the second wall surface 92a.
[0093] As shown in FIGS. 2 to 5, the second inner portion 115
extends in the axial direction of the double-headed piston 100 from
the inner portion of the second head 113 in the radial direction R.
The second inner portion 115 includes a second basal portion 115a
located near the second head 113 and a second distal portion 115b
located near the second shoe holder 112. The second distal portion
115b is located between the second head 113 and the second shoe
holder 112 as viewed in the radial direction R, more specifically,
located at the part of the second coupling portion 114 closer to
the second shoe holder 112 than the second head 103. The second
distal portion 115b corresponds to "an end of the inner portion
near the shoe holder."
[0094] As shown in FIG. 4, the second inner portion 115 is a plate
having a width in the widthwise direction W and a thickness in the
radial direction R. The second inner portion 115 includes a second
fixed-width portion 115c having a fixed width. The second
fixed-width portion 115c is located between the two ends 115a and
115b. In the present embodiment, the second fixed-width portion
115c has a width that is less than that of each of the two shoe
holders 102 and 112. The second distal portion 115b of the second
inner portion 115 is wider than the fixed-width portion 115c.
[0095] The second inner portion 115 is located further inward from
the side surface 113b of the second head 113. The second inner
portion 115 includes a second inner surface 115d opposing the
second wall surface 92a in the radial direction R. The second inner
surface 115d is curved in conformance with the second wall surface
92a. The second inner surface 115d is farther from the portion of
the second wall surface 92a opposing the second inner surface 115d
than the side surface 113b of the second head 113. That is, the
side surface 113b of the second head 113 and the second inner
surface 115d form a step so that the second inner surface 115d is
farther from the second wall surface 92a than the side surface 113b
of the second head 103. The step between the side surface 113b of
the second head 113 and the second inner surface 115d may have any
dimension, for example, less than or equal to 1 mm (excluding 0
mm). In each of the figures, to facilitate understanding, the
dimension of the step is larger than the actual one. Further, the
second distal portion 115b has an edge that is obliquely cut. Thus,
the edge of the second inner surface 115d near the second distal
portion 115b is inclined.
[0096] As shown in FIG. 5, the second inner portion 115 is located
at the inner side of the second shoe holder 112 in the radial
direction R. Thus, the second distal portion 115b of the second
inner portion 115 and the second shoe holder 112 form a step. The
second coupling portion 114 includes a second rib 119 that connects
the second shoe holder 112 and the second distal portion 115b of
the second inner portion 115, which form a step. The second rib 119
connects the second distal portion 115b of the second inner portion
115 to the second shoe holder 112 so that a second space A12 is
defined by the side of the second distal portion 115b of the second
inner portion 115 as viewed in the widthwise direction W. More
specifically, the second rib 119 is inclined as viewed in the
widthwise direction W. As shown in FIG. 4, the length X21 of the
second inner portion 115 in the axial direction of the
double-headed piston 100 is greater than the length X22 of the
second rib 119.
[0097] As shown in FIGS. 2 to 5, the thickness of the second plate
117 of the second coupling portion 114 is smaller than the widths
of the second inner portion 115 and the second outer portion 116.
The second plate 117 includes a second through hole 117a extending
in the widthwise direction W. The second through hole 117a is, for
example, defined by a wall recessed toward the second shoe holder
112 as viewed in the widthwise direction W and is in communication
with the interior of the second head 113, which is tubular and has
a bottom.
[0098] As shown in FIGS. 3 to 5, the outer surface of the neck
recesses 101a includes a rotation stopper 123 that restricts
rotation of the double-headed piston 100 in the two cylinder bores
91 and 92. The rotation stopper 123 is located closer to the second
shoe holder 112 than the neck recesses 101a, more specifically, on
the end of the outer surface of the neck 101 that is closer to the
second shoe holder 112. In other words, the rotation stopper 123
may be located on the outer surface of the neck 101 closer to the
second head 113 than the first head 103 or on the outer surface of
the neck 101 at a location that is closer to the second coupling
portion 114 than the first coupling portion 104. The rotation
stopper 123 extends in the widthwise direction W. As shown in FIG.
4, the two ends of the rotation stopper 123 in the widthwise
direction W extend out of the neck 101 as viewed in the radial
direction R. The rotation stopper 123 includes an outer surface
curved in conformance with the side wall inner surface 15a. The
outer surface of the rotation stopper 123 abuts against the side
wall inner surface 15a to restrict rotation of the double-headed
piston 100 in the cylinder bores 91 and 92.
[0099] In the present embodiment, the rotation stopper 123 is
arranged near the second shoe holder 112 and not near the first
shoe holder 102. Thus, the portion of the neck 101 near the first
shoe holder 102 is deformed more easily than the portion near the
second shoe holder 112, and the portion of the neck 101 near the
second shoe holder 112 has a higher strength than the portion of
the neck 101 near the first shoe holder 102.
[0100] Further, the double-headed piston 100 is movable to where
the rotation stopper 123 abuts against the open end of the first
cylinder bore 91 that is closer to the swash plate chamber A2. That
is, the portion of the neck 101 near the first shoe holder 102 of
the double-headed piston 100 can be partially inserted into the
first cylinder bore 91.
[0101] Fluid in the compression chambers A4 and A5 and the swash
plate applies load to the double-headed piston 100. Load includes
force applied from the swash plate 50 through the two shoes 121 and
122 and compression reaction force that results from the
compression of fluid in the compression chambers A4 and A5. The
force includes a component in the axial direction Z and a component
that acts toward the inner side in the radial direction R. That is,
the double-headed piston 100 receives bending load that acts toward
the inner side in the radial direction R.
[0102] Further, the degree of load applied to the double-headed
piston 100 varies depending on, for example, the inclination angle
of the swash plate 50, the position of the double-headed piston 100
during a single reciprocation, and the pressure of the compression
chambers A4 and A5. That is, in accordance with the operation
situation of the compressor 10, a low load may be applied to the
double-headed piston 100 (hereinafter referred to as "low-load
period"), and a high load that is higher than the low load may be
applied to the double-headed piston 100 (hereinafter referred to as
"high-load period").
[0103] During the low-load period, the double-headed piston 100
receives load that is less than a specific threshold value. The
low-load period may satisfy, for example, at least one of the
following two conditions: (A) the inclination angle of the swash
plate 50 is equal to the minimum inclination angle or closer to the
minimum inclination angle than the maximum inclination angle; and
(B) the compression reaction force that the double-headed piston
receives from the compression chambers A4 and A5 is less than a
threshold value.
[0104] During the high-load period, the double-headed piston 100
receives load that is greater than the specific threshold value.
The high-load period may satisfy, for example, at least one of the
following two conditions: (A) the inclination angle of the swash
plate 50 is equal to the maximum inclination angle or closer to the
maximum inclination angle than the minimum inclination angle; and
(B) the compression reaction force that the double-headed piston
receives from the compression chambers A4 and A5 is greater than or
equal to a threshold value.
[0105] However, the low-load period and the high-load period do not
have to be set in accordance with the above conditions. Instead,
the low-load period and the high-load period may be set in
accordance with, for example, the operation condition of the
compressor 10. The high-load period may be, for example, when the
compressor 10 is activated or when the vehicle is accelerated at a
rate that is greater than or equal to a predetermined threshold
acceleration rate. The low-load period may be when the compressor
10 is operated as the vehicle is traveling at a constant speed or
as the vehicle is accelerated at a rate that is less than the
predetermined threshold acceleration rate.
[0106] Alternatively, the low-load period and the high-load period
may be set in accordance with the operation condition of a vehicle
air-conditioner. For example, during the high-load period, the
vehicle air-conditioner may be activated or a passenger compartment
temperature may be maintained. As another option, during the
high-load period, the vehicle air-conditioner may be operated to
reach a set target temperature under the condition that the
difference of the set target temperature and the passenger
compartment temperature is greater than or equal to a threshold
value, and during the low-load period, the vehicle air-conditioner
may be operated to reach the set target temperature under the
condition that the difference of the set target temperature and the
passenger compartment temperature is less than a threshold
value.
[0107] The low load may be referred to as a first load, and the
high load may be referred to as a second load.
[0108] The double-headed piston 100 during the low-load period will
now be described.
[0109] Referring to FIG. 5, the double-headed piston 100 receives a
relatively small bending load during the low-load period. Thus, the
neck 101 resists deforming. In this case, the side surfaces 103b
and 113b of the heads 103 and 113 slide along (i.e., abut against)
the wall surfaces 91a and 92a of the cylinder bores 91 and 92 and
thus receive bending load. In this case, the distal portions 105b
and 115b of the Inner portions 105 and 115 are farther from the
wall surfaces 91a and 92a of the cylinder bores 91 and 92 than the
side surfaces 103b and 113b of the heads 103 and 113. Thus, the
double-headed piston 100 reciprocates with the distal portions 105b
and 115b separated from the wall surfaces 91a and 92a of the
cylinder bores 91 and 92. The low-load period may be when the neck
101 is not deformed or when the neck 101 is deformed but the distal
portions 105b and 115b do not abut against the wall surfaces 91a
and 92a of the cylinder bores 91 and 92.
[0110] The double-headed piston 100 during the high-load period
will now be described. In the present embodiment, the double-headed
piston 100 is located at the first position or the second position
during the high-load period.
[0111] As shown in FIG. 6, when the double-headed piston 100 is
located at the first position, the first distal portion 105b of the
first inner portion 105 is opposed to the first wall surface 91a in
the radial direction R. Further, when the double-headed piston 100
is located at the first position, the double-headed piston 100
receives a relatively large bending load. In this case, the neck
101 is deformed toward the inner side in the radial direction R so
that the entire double-headed piston 100 is bent and bulged toward
the inner side in the radial direction R.
[0112] When the double-headed piston 100 is bent, the side surfaces
103b and 113b of the heads 103 and 113 slide along (i.e., abut
against) the wall surfaces 91a and 92a, and the first distal
portion 105b (more specifically, portion of first inner surface
105d that corresponds to first distal portion 105b) slides along
the first wall surface 91a. That is, the side surfaces 103b and
113b of the heads 103 and 113 and the first distal portion 105b
receive bending load. In this case, since the distance from the
first distal portion 105b to the first shoe holder 102 in the axial
direction of the double-headed piston 100 is shorter than the
distance from the first head 103 to the first shoe holder 102,
bending moment that is produced at the double-headed piston 100 is
reduced as compared to when bending load is received only by the
heads 103 and 113. The first distal portion 105b corresponds to a
"load receiving portion."
[0113] The high-load period is when the neck 101 receives bending
load and deforms such that the distal portions 105b and 115b abut
against the wall surfaces 91a and 92a of the cylinder bores 91 and
92. That is, the specific threshold value refers to a lower limit
value of load in which the distal portions 105b and 115b abut
against the wall surfaces 91a and 92a of the cylinder bores 91 and
92 when the neck 101 is deformed.
[0114] When the first distal portion 105b abuts against the first
wall surface 91a, further deformation of the double-headed piston
100 is restricted. In addition, when the double-headed piston 100
is bent, priority is given to the sliding of the edge of the first
distal portion 105b, which is obliquely inclined, along the first
wall surface 91a. When the first distal portion 105b slides along
the first wall surface 91a, the first fixed-width portion 105c is
separated from the first wall surface 91a.
[0115] Further, a first oil collection region A21 is defined
between the side surface 103b of the first head 103 and the first
distal portion 105b. The first oil collection region A21 is located
between the first wall surface 91a and the first fixed-width
portion 105c. Oil suspended in refrigerant flows into the first oil
collection region A21. Then, the oil is supplied to where the side
surface 103b of the first head 103 slides along (i.e., abuts
against) the wall surface 91a and to where the first distal portion
105b slides along the first wall surface 91a.
[0116] When the double-headed piston 100 is located at the first
position, the second projection 82 of the swash plate 50 is located
in the second space A12. This avoids interference between the
double-headed piston 100 and the second projection 82. The second
space A12 does not interfere with the coupling receiving portion 76
and the second projection 82 regardless of the inclination angle of
the swash plate 50 and the position of the double-headed piston 100
in the cylinder bores 91 and 92.
[0117] As shown in FIG. 7, when the double-headed piston 100 is
located at the second position, the second distal portion 115b of
the second inner portion 115 is opposed to the second wall surface
92a in the radial direction R. Further, since the double-headed
piston 100 receives a relatively large bending load, the neck 101
is deformed toward the inner side in the radial direction R so that
the entire double-headed piston 100 is bent and bulged toward the
inner side in the radial direction R. The side surface 103b of the
head 103 slides along the first wall surfaces 91a, and the side
surface 113b of the second head 113 and the second distal portion
115b (more specifically, portion of second inner surface 115d that
corresponds to second distal portion 115b) slide along the second
wall surface 92a. That is, the side surfaces 103b and 113b of the
heads 103 and 113 and the second distal portion 115b receive
bending load. In this case, the distance from the second distal
portion 115b to the second shoe holder 112 in the axial direction
of the double-headed piston 100 is shorter than the distance from
the second head 113 to the second shoe holder 112. This reduces the
bending moment produced at the double-headed piston 100 as compared
to when the bending load is received only by the heads 103 and 113.
The second distal portion 115b corresponds to the "load receiving
portion."
[0118] When the second distal portion 115b abuts against the second
wall surface 92a, further deformation of the double-headed piston
100 is restricted. In addition, when the double-headed piston 100
is bent, priority is given to the sliding of the edge of the second
distal portion 115b, which is obliquely inclined, along the second
wall surface 92a. The second fixed-width portion 115c is separated
from the second wall surface 92a.
[0119] Further, a second oil collection region A22 is defined
between the side surface 113b of the second head 113 and the second
distal portion 115b. The second oil collection region A22 is
located between the second wall surface 92a and the second
fixed-width portion 115c. Oil suspended in refrigerant flows into
the second oil collection region A22. Then, the oil is supplied to
where the side surface 113b of the second head 113 slides along the
second wall surface 92a and to where the second distal portion 115b
slides along the second wall surface 92a.
[0120] When the double-headed piston 100 is located at the second
position, the first projection 81 of the swash plate 50 is located
in the first space A11. This avoids interference between the
double-headed piston 100 and the first projection 81. The first
space A11 does not interfere with the double-headed piston 100 and
the first projection 81 regardless of the inclination angle of the
swash plate 50 and the position of the double-headed piston 100 in
the cylinder bores 91 and 92.
[0121] The above embodiment has the advantages described below.
[0122] (1) The compressor 10 is of a double-headed piston type
swash plate type that compresses fluid in the compression chambers
A4 and A5 of the cylinder bores 91 and 92 when rotation of the
swash plate 50 rotates the double-headed piston 100 in the two
cylinder bores 91 and 92.
[0123] The double-headed piston 100 includes the two shoe holders
102 and 112, which hold the two shoes 121 and 122 and are opposed
to each other in the axial direction of the double-headed piston
100, and the neck 101, which couples the two shoe holders 102 and
112 and is located at a circumferential side of the swash plate 50.
The neck 101 is deformable in the radial direction R. The
double-headed piston 100 includes the two heads 103 and 113, which
are respectively arranged at the two ends of the double-headed
piston 100 in the axial direction, and the two coupling portions
104 and 114, which respectively couple the two heads 103 and 113 to
the two shoe holders 102 and 112.
[0124] In such a structure, when the double-headed piston 100
receives load, the neck 101 is deformed toward the inner side in
the radial direction R so that the double-headed piston 100 is bent
and bulged toward the inner side in the radial direction R. The
coupling portions 104 and 114 include the distal portions 105b and
115b, which serve as the load receiving portions receiving bending
load that is applied from the swash plate 50 to the double-headed
piston 100 and acts toward the inner side in the radial direction
R. The distal portions 105b and 115b are located between the heads
103 and 113 and the shoe holders 102 and 112 as viewed in the
radial direction R. During the low-load period, the load applied to
the double-headed piston 100 is less than the specific threshold
value. In this case, the distal portions 105b and 115b are
separated from the wall surfaces 91a and 92a of the cylinder bores
91 and 92. During the high-load period, the load applied to the
double-headed piston 100 is greater than the specific threshold
value. In this case, when the neck 101 is deformed, each of the
distal portions 105b and 115b abuts against the corresponding wall
surface (first distal portion 105b abuts against first wall surface
91a and second distal portion 115b abuts against second wall
surface 92a) and receives bending load.
[0125] In such a structure, during the low-load period, the side
surfaces 103b and 113b of the heads 103 and 113 abut against the
wall surfaces 91a and 92a of the cylinder bores 91 and 92, and the
distal portions 105b and 115b do not abut against the wall surfaces
91a and 92a. This limits the power loss of the double-headed piston
100 that may occur when the distal portions 105b and 115b abut
against the wall surfaces 91a and 92a.
[0126] During the high-load period, one of the two distal portions
105b and 115b receives bending load. Thus, three portions, namely,
one of the two distal portions 105b and 115b and the side surfaces
103b and 113b of the heads 103 and 113, receive bending load. In
this case, since the distance from the distal portions 105b and
115b to the shoe holders 102 and 112 to which bending load is
applied is shorter in the axial direction of the double-headed
piston 100 than the distance from the heads 103 and 113 to the shoe
holders 102 and 112. This reduces the bending moment and thus
reduces stress that is applied to the double-headed piston 100.
Accordingly, the strength that counters bending load of the
double-headed piston 100 is increased. Further, the double-headed
piston 100 receives the bending load over more portions during the
high-load period than during the low-load period. This disperses
the bending load and thus limits local wear.
[0127] (2) The distal portions 105b and 115b of the inner portions
105 and 115 are located closer to the shoe holders 102 and 112 than
the heads 103 and 113. This shortens the distance from each of the
portions that receive bending load (i.e., distal portions 105b and
115b serving as load receiving portions) to each of the portions
where bending load is applied (i.e., shoe holders 102 and 112).
Thus, bending moment is reduced in a further preferred manner, and
the strength that counters bending load is further increased.
[0128] (3) The coupling portions 104 and 114 respectively include
the outer portions 106 and 116, which extend in the axial direction
of the double-headed piston 100, and the inner portions 105 and
115, which are located at the inner sides of the outer portions 106
and 116 in the radial direction R and extended from the heads 103
and 113 in the axial direction of the double-headed piston 100. The
inner portions 105 and 115 are opposed to the outer portions 106
and 116 in the radial direction R. The inner portions 105 and 115
respectively include the inner surfaces 105d and 115, which are
opposed in the radial direction R to the wall surfaces 91a and 92a
of the cylinder bores 91 and 92. The inner surfaces 105d and 115d
and the side surfaces 103b and 113b of the heads 103 and 113 form a
step so that the inner surfaces 105d and 115d are located further
inward (i.e., farther from wall surfaces 91a and 92a of cylinder
bores 91 and 92) than the side surfaces 103b and 113b. The distal
portions 105b and 115b, which are the ends of the inner portions
105 and 115 located near the shoe holders 102 and 112, serve as the
load receiving portions that receive bending load during the
high-load period. In such a structure, since the inner surfaces
105d and 115d and the side surfaces 103b and 113b of the heads 103
and 113 form a step, the distal portions 105b and 115b are
separated from the wall surfaces 91a and 92a of the cylinder bores
91 and 92 during the low-load period in which the neck 101 is not
deformed. When the neck 101 is deformed such that the double-headed
piston 100 is bent and bulged toward the inner side in the radial
direction R, one of the distal portions 105b and 115b abuts against
the wall surface of the corresponding cylinder bore and receives
bending load. Thus, advantage (1) is obtained in a relatively
simple structure.
[0129] In particular, the inner portions 105 and 115 extend from
the heads 103 and 113 in the axial direction of the double-headed
piston 100, and the distal portions 105b and 115b of the inner
portions 105 and 115 are parts of the inner portions 105 and 115
located closest to the shoe holders 102 and 112. When the distal
portions 105b and 115b receive bending load, the distance from each
of the portions that receive bending load to each of the portions
where bending load is applied is further shortened. This reduces
bending moment.
[0130] (4) The inner portions 105 and 115 respectively include the
fixed-width portions 105c and 115c, each having a fixed width. The
distal portions 105b and 115b are wider than the fixed-width
portions 105c and 115c. This increases the areas of the portions
that receive bending load and thus reduces wear of the distal
portions 105b and 115b (more specifically, portions of inner
surfaces 105d and 115d that form distal portions 105b and 115b).
Further, the fixed-width portions 105c and 115c that do not abut
against the wall surfaces 91a and 92a of the cylinder bores 91 and
92 are narrow. This reduces the weight of the double-headed piston
100.
[0131] (5) The coupling portions 104 and 114 respectively include
the ribs 109 and 119 that connect the distal portions 105b and 115b
and the shoe holders 102 and 112 so that the spaces A1 and A12 are
defined beside the distal portions 105b and 115b as viewed in the
widthwise direction W. This allows the swash plate 50 to pass the
spaces A11 and A12. Thus, interference between the swash plate 50
and the double-headed piston 100 is avoided.
[0132] (6) The lengths X11 and X21 of the inner portions 105 and
115 are larger than the lengths X12 and X22 of the ribs 109 and 119
in the axial direction of the double-headed piston 100. In such a
structure, the distal portions 105b and 115b of the inner portions
105 and 115 become close to the shoe holders 102 and 112 to avoid
interference with the swash plate 50. This avoids interference with
the swash plate 50 and increases the strength that counters bending
load of the double-headed piston 100 in the radial direction R.
[0133] (7) The cylinder bores 91 and 92 include oil. During the
high-load period, the oil enters the oil collection regions A21 and
A22 defined between the distal portions 105b and 115b, which abut
against the wall surfaces 91a and 92a of the cylinder bores 91 and
92, and the heads 103 and 113. The oil that flow into the oil
collection regions A21 and A22 is supplied to where the distal
portions 105b and 115b abut against the wall surfaces 91a and 92a
and to where the side surfaces 103b and 113b of the heads 103 and
113 abut against the wall surfaces 91a and 92a. Thus, the abut
portions are supplied with a sufficient amount of oil, and wear is
reduced.
[0134] (8) The double-headed piston 100 reciprocates from the first
position to the second position when the inclination angle of the
swash plate 50 is the maximum. The first distal portion 105b is
opposed to the first wall surface 91a when the double-headed piston
100 is located at the first position. The second distal portion
115b is opposed to the second wall surface 92a when the
double-headed piston 100 is located at the second position. In such
a structure, when the double-headed piston 100 is located at least
at the first location or the second location, the distal portions
105b and 115b receive bending load. This avoids situations in which
the distal portions 105b and 115b are unable to receive bending
load when receiving a relatively high load.
[0135] (9) The compressor 10 includes the actuator 70 that changes
the inclination angle of the swash plate 50. The actuator 70
includes the movable body 71, which is movable in the axial
direction Z of the rotation shaft 20, and the partition 72, which
defines the control chamber A3 in cooperation with the movable body
71. The compressor 10 changes the inclination angle of the swash
plate 50 when the movable body 71 moves in accordance with the
pressure of the control chamber A3. Thus, adjustment of the
pressure of the control chamber A3 allows for variable
displacement.
[0136] When variable displacement is performed, the controllability
of the variable displacement needs to be increased. In the present
embodiment, the coupling portions 104 and 114 are relatively narrow
(for example, less than or equal to width of neck 101) so that the
coupling portions 104 and 114 are easily deformed in the widthwise
direction W. Thus, as compared to the piston that is wide in the
widthwise direction W to receive side force, the weight of the
double-headed piston 100 is reduced. This increases the
controllability of variable displacement.
[0137] (10) The second head 113 has a smaller diameter than the
first head 103. In such a structure, the first head 103 and the
second head 113 respectively include refrigerant pressure receiving
areas that differ from each other. Accordingly, the first head 103
and the second head 113 have different compression reaction forces
that result from the compression of fluid. This allows variable
displacement to be performed relatively easily. Thus, the
controllability of variable displacement is increased.
[0138] (11) The neck recesses 101 include the rotation stopper 123
that restricts rotation of the double-headed piston 100 in the two
cylinder bores 91 and 92. The rotation stopper 123 is located at
the portion of the neck 101 that is closer to the second head 113
than the first head 103. In such a structure, the rotation stopper
123 is located at the small diameter side where the strength has a
tendency of being lower than the large diameter side. This limits
decreases in the strength of the second head 113, which is an
undesirable situation that may occur when the heads 103 and 113
have different diameters.
[0139] It should be apparent to those skilled in the art that the
present invention may be embodied in many other specific forms
without departing from the spirit or scope of the invention.
Particularly, it should be understood that the present invention
may be embodied in the following forms.
[0140] The coupling portions 104 and 114 are not limited to any
specific shape. For example, each of the coupling portions may be
smaller than the heads 103 and 113 and have a tubular or
cylindrical shape.
[0141] The load receiving portions that receive bending load do not
have to be the distal portions 105b and 115b. Instead, the load
receiving portions may be, for example, projections that project
from the inner surfaces 105d and 115d. In this case, the inner
surfaces 105d and 115d may be located sufficiently outward from the
side surfaces 103b and 113b of the heads 103 and 113 in the radial
direction R so that the projections do not slide along the wall
surfaces 91a and 92a of the cylinder bores 91 and 92 during the low
load. Alternatively, the dimensions and the like of the projections
may be adjusted.
[0142] Further, the load receiving portions may be the fixed-width
portions 105c and 115c. In this case, the fixed-width portions 105c
and 115c project further inward in the radial direction R (i.e.,
toward portions of wall surfaces 91a and 92a opposing fixed-width
portions 105c and 115c) from the distal portions 105b and 115b. In
the same manner, the load receiving portions may be the basal
portions 105a and 115a of the inner portions 105 and 115. That is,
the load receiving portions may be located at the portions of the
coupling portions 104 and 114 closer to the heads 103 and 113 than
the shoe holders 102 and 112 (between shoe holders 102 and 112 and
heads 103 and 113). However, it is preferred that the load
receiving portions be the distal portions 105b and 115b in order to
further reduce bending moment.
[0143] The inner portions 105 and 115 may be omitted. In this case,
for example, protrusions may protrude from the middle portions of
the outer portions 106 and 116 toward the inner side in the radial
direction R, and the protrusions may include distal portions that
are separated from the wall surfaces 91a and 92a of the cylinder
bores 91 and 92. In such a structure, when the neck 101 is
deformed, the distal portions of the protrusions abut against the
wall surfaces 91a and 92a. In other words, the load receiving
portions may have any specific shape as long as the coupling
portions 104 and 114 located between the heads 103 and 113 and the
shoe holders 102 and 112 include the load receiving portions.
[0144] The two fixed-width portions 105c and 115c may be omitted.
For example, the inner portions 105 and 115 may be gradually
narrowed or widened from the basal portions 105a and 115a toward
the distal portions 105b and 115b. In this case, the distal
portions 105b and 115b may be wider than the portions of the inner
portions 105 and 115 excluding the distal portions 105b and 115b.
Alternatively, the distal portions 105b and 115b may be narrower
than the shoe holders 102 and 112. As another option, one of the
two fixed-width portions 105c and 115c may be omitted.
[0145] The fixed-width portions 105c and 115c may be wider than the
shoe holders 102 and 112. In other words, the inner portions 105
and 115 may be at least partially narrower than the shoe holders
102 and 112, and the entire inner portions 105 and 115 may be wider
than the shoe holders 102 and 112. Alternatively, the inner
positions 105 and 115 may be wider than the neck 101.
[0146] Each of the coupling portions 104 and 114 may have a width
that is less than or equal to that of the neck 101. Alternatively,
each of the coupling portions 104 and 114 may have a width that is
greater than that of the neck 101.
[0147] The outer portions 106 and 116 may be thicker or thinner
than the inner portions 105 and 115. Further, at least one of the
two outer portions 106 and 116 may be omitted.
[0148] In the embodiment, the first coupling portion 104 in the
axial direction of the double-headed piston 100 is longer than the
second coupling portion 114. Instead, the two coupling portions 104
and 114 may have the same length. Alternatively, the second
coupling portion 114 may be longer than the first coupling portion
104.
[0149] The first head 103 and the second head 113 may have the same
size. Alternatively, the second head 113 may be larger than the
first head 103. In addition, the heads 103 and 113 may be
cylindrical.
[0150] The ribs 109 and 119 may have any specific structure as long
as the ribs 109 and 119 do not interfere with the swash plate 50.
For example, the ribs 109 and 119 may be L-shaped or reverse
L-shaped as viewed in the widthwise direction W.
[0151] The neck 101 and the coupling portions 104 and 114 are not
limited to the forms illustrated in the embodiment.
[0152] The neck recess 101a may have any shape. Further, the neck
recess 101a may be omitted.
[0153] The through holes 107a and 117a are not limited to any
specific shape. Further, at least one of the through holes 107a and
117a may be omitted, and at least one of the plates 107 and 117 may
be omitted.
[0154] The rotation stopper 123 may be located closer to the first
shoe holder 102 than the neck recesses 101a. Alternatively, the
rotation stopper 123 may be located closer to both of the first
shoe holder 102 and the second shoe holder 112 than the neck
recesses 101a. Further, the rotation stopper 123 may be
omitted.
[0155] The actuator 70 may have any specific structure as long as
the actuator 70 is capable of changing the inclination angle of the
swash plate 50. In the same manner, the link mechanism 60 may have
any specific structure as long as the link mechanism 60 is capable
of transmitting power from the rotation shaft 20 to the swash plate
50.
[0156] At least one of the first projection 81 and the second
projection 82 may be omitted.
[0157] The number of cylinder bores 91 and 92 and the number of
double-headed pistons 100 are not limited to those of the
embodiment and may each be, for example, one.
[0158] The lengths X11 and X21 of the inner portions 105 and 115
may be less than or equal to the lengths X12 and X22 of the ribs
109 and 119.
[0159] At least one of each of the inner portions 105 and 115 and
each of the outer portions 106 and 116 may be slightly inclined
with respect to the axial direction of the double-headed piston
100.
[0160] The compressor 10 of the embodiment is of a variable
displacement type. Instead, the compressor 10 may be of a fixed
displacement type in which the inclination angle of the swash plate
50 is fixed.
[0161] The fluid that is subject to compression by the compressor
10 is not limited to refrigerant and may be, for example, air.
[0162] The compressor 10 does not have to be installed in a
vehicle.
[0163] The above embodiment may be combined with each of the
modified examples.
[0164] Therefore, the present examples and embodiments are to be
considered as illustrative and not restrictive and the invention is
not to be limited to the details given herein, but may be modified
within the scope and equivalence of the appended claims.
* * * * *