U.S. patent application number 15/049216 was filed with the patent office on 2016-09-01 for variable displacement swash plate type 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 Shohei FUJIWARA, Kazunari HONDA, Takahiro SUZUKI, Shinya YAMAMOTO.
Application Number | 20160252084 15/049216 |
Document ID | / |
Family ID | 56798766 |
Filed Date | 2016-09-01 |
United States Patent
Application |
20160252084 |
Kind Code |
A1 |
FUJIWARA; Shohei ; et
al. |
September 1, 2016 |
VARIABLE DISPLACEMENT SWASH PLATE TYPE COMPRESSOR
Abstract
A variable displacement swash plate type compressor includes a
housing. The housing includes a first cylinder bore and a second
cylinder bore. The second cylinder bore has a smaller diameter than
the first cylinder bore. A first thrust bearing is provided between
one end side of a drive shaft and the housing so as to receive a
thrust force acting on the drive shaft in a direction toward the
one end side, and a second thrust bearing is provided between an
opposite end side of the drive shaft in a direction toward the
opposite end side. A second spring constant of the second thrust
bearing is greater than a first spring constant of the first thrust
bearing.
Inventors: |
FUJIWARA; Shohei;
(Kariya-shi, JP) ; YAMAMOTO; Shinya; (Kariya-shi,
JP) ; SUZUKI; Takahiro; (Kariya-shi, JP) ;
HONDA; Kazunari; (Kariya-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KABUSHIKI KAISHA TOYOTA JIDOSHOKKI |
Kariya-shi |
|
JP |
|
|
Assignee: |
KABUSHIKI KAISHA TOYOTA
JIDOSHOKKI
Kariya-shi
JP
|
Family ID: |
56798766 |
Appl. No.: |
15/049216 |
Filed: |
February 22, 2016 |
Current U.S.
Class: |
417/269 |
Current CPC
Class: |
F04B 27/0878 20130101;
F04B 27/18 20130101; F04B 27/1054 20130101; F04B 27/1045
20130101 |
International
Class: |
F04B 27/22 20060101
F04B027/22; F04B 27/10 20060101 F04B027/10 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 26, 2015 |
JP |
2015-036866 |
Claims
1. A variable displacement swash plate type compressor comprising:
a drive shaft; a housing that rotatably supports the drive shaft,
the housing including a first cylinder bore formed at one end side
of the drive shaft, a second cylinder bore formed at an opposite
end side of the drive shaft, and a swash plate chamber formed
between the first cylinder bore and the second cylinder bore; a
swash plate that is rotatable in the swash plate chamber by
rotation of the drive shaft; a link mechanism that is provided
between the drive shaft and the swash plate and permits change of
an inclination angle of the swash plate in a direction
perpendicular to an axis of the drive shaft; a double-headed piston
that defines a first compression chamber in the first cylinder bore
and defines a second compression chamber in the second cylinder
bore; a conversion mechanism that reciprocates the piston in the
first and second cylinder bores at a stroke corresponding to the
inclination angle along with the rotation of the swash plate; an
actuator capable of changing the inclination angle; and a control
mechanism that controls the actuator, wherein the second cylinder
bore has a smaller diameter than the first cylinder bore, a first
thrust bearing is provided between the one end side of the drive
shaft and the housing so as to receive a thrust force acting on the
drive shaft in a direction toward the one end side, a second thrust
bearing is provided between the opposite end side of the drive
shaft and the housing so as to receive a thrust force acting on the
drive shaft in a direction toward the opposite end side, and a
second spring constant of the second thrust bearing is greater than
a first spring constant of the first thrust bearing.
2. The variable displacement swash plate type compressor according
to claim 1, wherein the housing includes a first cylinder block
disposed at the one end side of the drive shaft and a second
cylinder block disposed at the opposite end side of the drive
shaft, the first cylinder block having the first cylinder bore, the
second cylinder block having the second cylinder bore, a first
annular portion formed into an annular shape around the axis of the
drive shaft is disposed at the one end side of the drive shaft, a
second annular portion formed into an annular shape around the axis
of the drive shaft is disposed at the opposite end side of the
drive shaft, the first thrust bearing is disposed between the first
cylinder block and the first annular portion, a region where the
first thrust bearing is supported by the first annular portion and
a region where the first thrust bearing is supported by the first
cylinder block are radially shifted from each other, the second
thrust bearing is disposed between the second cylinder block and
the second annular portion, and a region where the second thrust
bearing is supported by the second annular portion and a region
where the second thrust bearing is supported by the second cylinder
block are radially shifted from each other.
3. The variable displacement swash plate type compressor according
to claim 1, wherein the housing includes a first cylinder block
disposed at the one end side of the drive shaft and a second
cylinder block disposed at the opposite end side of the drive
shaft, the first cylinder block having the first cylinder bore, the
second cylinder block having the second cylinder bore, a first
annular portion formed into an annular shape around the axis of the
drive shaft is disposed on the one end side of the drive shaft, a
second annular portion formed into an annular shape around the axis
of the drive shaft is disposed at the opposite end side of the
drive shaft, the first thrust bearing is disposed between the first
cylinder block and the first annular portion, the second thrust
bearing is disposed between the second cylinder block and the
second annular portion, the first thrust bearing includes a one
end-side first race that faces the first cylinder block, a one
end-side second race that faces the first annular portion, and a
plurality of first rolling elements that is held between the one
end-side first race and the one end-side second race, the second
thrust bearing includes an opposite end-side first race that faces
the second cylinder block, an opposite end-side second race that
faces the second annular portion, and a plurality of second rolling
elements that is held between the opposite end-side first race and
the opposite end-side second race, and a thickness of at least one
of the opposite end-side first race and the opposite end-side
second race is greater than a thickness of the one end-side first
race and the one end-side second race.
4. The variable displacement swash plate type compressor according
to claim 1, wherein an outer diameter of the second thrust bearing
is smaller than an outer diameter of the first thrust bearing.
5. The variable displacement swash plate type compressor according
to claim 1, wherein the actuator includes a partition body that is
provided on the drive shaft, a connecting portion that is connected
to the swash plate, a movable body that is movable in the swash
plate chamber in a direction of the axis of the drive shaft, and a
control pressure chamber that is defined by the partition body and
the movable body and moves the movable body so as to increase the
inclination angle by introducing refrigerant from a discharge
chamber, and the actuator is disposed on the side of the second
cylinder bore with respect to the swash plate in the swash plate
chamber.
Description
TECHNICAL FIELD
[0001] The present invention relates to a variable displacement
swash plate type compressor.
BACKGROUND ART
[0002] Japanese Patent Laid-Open No. 4-94470 discloses a
conventional variable displacement swash plate type compressor
(hereinafter simply referred to as a compressor). As shown in FIGS.
4 and 8 of this publication, the compressor includes a drive shaft,
a housing, a swash plate, a link mechanism, double-headed pistons,
a conversion mechanism, an actuator, and a control mechanism.
[0003] The housing rotatably supports the drive shaft. First
cylinder bores are formed at a rear side in the housing, i.e., at
one end side of the drive shaft. Second cylinder bores are formed
at a front side in the housing, i.e., an opposite end side of the
drive shaft. The diameter of the second cylinder bores is smaller
than the diameter of the first cylinder bores. A swash plate
chamber is formed in the housing between the first cylinder bores
and the second cylinder bores.
[0004] A first thrust bearing is provided between the one end side
of the drive shaft and the housing. A second thrust bearing is
provided between the opposite end side of the drive shaft and the
housing. The swash plate is disposed in the swash plate chamber in
a state in which the drive shaft is inserted therethrough, and is
rotatable by rotation of the drive shaft. The link mechanism is
provided between the drive shaft and the swash plate and permits
change of an inclination angle of the swash plate. Here, the
inclination angle refers to an angle of the swash plate with
respect to a direction perpendicular to an axis of the drive
shaft.
[0005] The double-headed pistons define first compression chambers
in the first cylinder bores and define second compression chambers
in the second cylinder bores. Heads of the pistons on the side of
the second cylinder bores have a smaller diameter than heads of the
pistons on the side of the first cylinder bores so as to correspond
to the diameters of the first and second cylinder bores. The
conversion mechanism reciprocates the pistons in the first and
second cylinder bores at a stroke corresponding to the inclination
angle along with the rotation of the swash plate. The actuator is
capable of changing the inclination angle. The control mechanism
controls the actuator.
[0006] In this compressor, by reciprocation of the pistons in the
first and second cylinder bores, refrigerant is introduced into the
first and second compression chambers, compressed therein, and
discharged therefrom. At this time, the first thrust bearing
receives a thrust force generated by a compression reaction force
in the second compression chambers, which acts on the drive shaft
in a direction toward the one end side, and the second thrust
bearing receives a thrust force generated by a compression reaction
force in the first compression chambers, which acts on the drive
shaft in a direction toward the opposite end side. In addition, in
this compressor, since the actuator is capable of changing the
inclination angle of the swash plate, discharge capacity of the
refrigerant can be changed.
[0007] However, in the above-described conventional compressor, no
difference is present between the first thrust bearing and the
second thrust bearing. On the other hand, in this compressor, since
the diameter of the second cylinder bores and the diameter of the
piston heads on the side of the second cylinder bores are smaller
than the diameter of the first cylinder bores and the diameter of
the piston heads on the side of the first cylinder bores, pressure
receiving area of the piston heads is larger on the side of the
first cylinder bores than on the side of the second cylinder bores.
Thus, as the discharge capacity increases, the thrust force toward
the opposite end side of the drive shaft becomes larger than the
thrust force toward the one end side of the drive shaft. Then, if
the second thrust bearing is excessively deformed in the axial
direction of the drive shaft, durability may be decreased.
Furthermore, there is a risk that the drive shaft is excessively
displaced toward the opposite end and a gap is created between the
drive shaft and the first thrust bearing or between the first
thrust bearing and the housing. As a result, the drive shaft
wobbles, and this leads to an increase of vibration and noise
caused by the vibration at the time of operation.
[0008] One possible solution to this problem may be to configure
both the first and second thrust bearings to have a large spring
constant. In this case, although the decrease in durability and the
wobbling of the drive shaft as described above may be inhibited,
when the discharge capacity is small, drag resistances of the first
and second thrust bearings acting on the drive shaft increases. As
a result, substantial power loss occurs in this compressor.
[0009] The present invention has been made in view of the
conventional circumstances described above, and an object of the
invention is to provide a variable displacement swash plate type
compressor capable of exhibiting excellent durability and
inhibiting vibration and noise caused by the vibration at the time
of operation with less power loss.
SUMMARY OF THE INVENTION
[0010] A variable displacement swash plate type compressor of the
present invention comprises: a drive shaft; a housing that
rotatably supports the drive shaft, the housing including a first
cylinder bore formed at one end side of the drive shaft, a second
cylinder bore formed at an opposite end side of the drive shaft,
and a swash plate chamber formed between the first cylinder bore
and the second cylinder bore; a swash plate that is rotatable in
the swash plate chamber by rotation of the drive shaft; a link
mechanism that is provided between the drive shaft and the swash
plate and permits change of an inclination angle of the swash plate
in a direction perpendicular to an axis of the drive shaft; a
double-headed piston that defines a first compression chamber in
the first cylinder bore and defines a second compression chamber in
the second cylinder bore; a conversion mechanism that reciprocates
the piston in the first and second cylinder bores at a stroke
corresponding to the inclination angle along with the rotation of
the swash plate; an actuator capable of changing the inclination
angle; and a control mechanism that controls the actuator. The
second cylinder bore has a smaller diameter than the first cylinder
bore. A first thrust bearing is provided between the one end side
of the drive shaft and the housing so as to receive a thrust force
acting on the drive shaft in a direction toward the one end side. A
second thrust bearing is provided between the opposite end side of
the drive shaft and the housing so as to receive a thrust force
acting on the drive shaft in a direction toward the opposite end
side. A second spring constant of the second thrust bearing is
greater than a first spring constant of the first thrust
bearing.
[0011] Other aspects and advantages of the present invention will
be apparent from the embodiments disclosed in the following
description and the attached drawings, the illustrations
exemplified in the drawings, and the concept of the invention
disclosed in the entire description and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a cross-sectional view of a compressor according
to Embodiment 1 at the time of minimum displacement.
[0013] FIG. 2 is a cross-sectional view of the compressor according
to Embodiment 1 at the time of maximum displacement.
[0014] FIG. 3 is a schematic diagram showing a control mechanism of
the compressor according to Embodiment 1.
[0015] FIG. 4 is an enlarged cross-sectional view of an essential
part of the compressor according to Embodiment 1, showing first
cylinder bores, a first thrust bearing, and the like.
[0016] FIG. 5 is an enlarged cross-sectional view of an essential
part of the compressor according to Embodiment 1, showing second
cylinder bores, a second thrust bearing, and the like.
[0017] FIG. 6 is a schematic diagram of a compressor according to a
comparative embodiment, showing states in which the drive shaft is
supported by first and second thrust bearings; (A) shows the state
when a thrust force acting on the drive shaft is small; and (B)
shows the state when a thrust force acting on the drive shaft in a
direction toward the opposite end of the drive shaft is large.
[0018] FIG. 7 is a schematic diagram of the compressor according to
Embodiment 1, showing states in which the drive shaft is supported
by the first and second thrust bearings; (A) shows the state when a
thrust force acting on the drive shaft is small; and (B) shows the
state when a thrust force acting on the drive shaft in a direction
toward the opposite end of the drive shaft is large.
[0019] FIG. 8 is an enlarged cross sectional view of an essential
part of a compressor according to Embodiment 2, showing second
cylinder bores, a second thrust bearing, and the like.
[0020] FIG. 9 is an enlarged cross sectional view of an essential
part of a compressor according to Embodiment 3, showing second
cylinder bores, a second thrust bearing, and the like.
[0021] FIG. 10 is an enlarged cross sectional view of an essential
part of a compressor according to Embodiment 4, showing second
cylinder bores, a second thrust bearing, and the like.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0022] Embodiments 1 to 4, which embody the present invention, will
be described below with reference to the drawings. These
compressors are mounted on vehicles and constitute refrigeration
circuits of vehicle air-conditioning apparatus.
Embodiment 1
[0023] As shown in FIGS. 1 and 2, the compressor of Embodiment 1 is
a double-headed piston compressor and comprises a housing 1, a
drive shaft 3, a swash plate 5, a link mechanism 7, a plurality of
double-headed pistons 9, a plurality of pairs of shoes 11a, 11b,
and an actuator 13. This compressor further comprises a control
mechanism 15 as shown in FIG. 3.
[0024] As shown in FIGS. 1 and 2, the housing 1 has a first housing
17, a second housing 19, a first cylinder block 21, a second
cylinder block 23, a first valve forming plate 39, and a second
valve forming plate 41. In this embodiment, the front-rear
direction of the compressor is defined on the assumption that the
side on which the first housing 17 is disposed is the front side of
the compressor, and the side on which the second housing 19 is
disposed is the rear side of the compressor. The front side of the
compressor corresponds to "one end side of the drive shaft" in the
present invention, and the rear side of the compressor corresponds
to "an opposite end side of the drive shaft" in the present
invention.
[0025] The first housing 17 has a boss 17a projecting frontward. A
shaft seal device 25 is provided in the boss 17a. The first housing
17 includes therein a first suction chamber 27a and a first
discharge chamber 29a. The first suction chamber 27a is formed into
an annular shape and located on an inner circumferential side in
the first housing 17. The first discharge chamber 29a is also
formed into an annular shape and located on an outer
circumferential side of the first suction chamber 27a in the first
housing 17.
[0026] The first housing 17 further includes a first front
communication passage 18a. The front end of the first front
communication passage 18a communicates with the first discharge
chamber 29a, and the rear end thereof opens at the rear end face of
the first housing 17.
[0027] The second housing 19 includes apart of the control
mechanism 15 mentioned above. The second housing 19 also includes a
second suction chamber 27b, a second discharge chamber 29b, and a
pressure regulation chamber 31. The pressure regulation chamber 31
is located in the central part of the second housing 19. The second
suction chamber 27b is formed into an annular shape and located on
an outer circumferential side of the pressure regulation chamber 31
in the second housing 19. The second discharge chamber 29b is also
formed into an annular shape and located on an outer
circumferential side of the second suction chamber 27b in the
second housing 19.
[0028] The second housing 19 further includes a first rear
communication passage 20a. The rear end of the first rear
communication passage 20a communicates with the second discharge
chamber 29b, and the front end thereof opens at the front end face
of the second housing 19.
[0029] The first cylinder block 21 is provided on the front side in
the compressor and located between the first housing 17 and the
second cylinder block 23. The first cylinder block 21 includes a
plurality of first cylinder bores 21a extending in the direction of
the axis O of the drive shaft 3 and arranged at equiangular
intervals in a circumferential direction. As shown in FIG. 4, the
first cylinder bores 21a have a bore diameter of the length L1.
[0030] The first cylinder block 21 has a first shaft hole 21b
through which the drive shaft 3 is inserted. A first sliding
bearing 22a is provided in the first shaft hole 21b. The first
cylinder block 21 further includes a first recess 21c that
communicates with the first shaft hole 21b from the rear side of
the compressor. The first recess 21c is coaxial with the first
shaft hole 21b and has an inner diameter of the length L2, which is
larger than the inner diameter of the first shaft hole 21b. At the
front wall of the first recess 21c, a first recessed surface 21d
that is recessed toward the front side of the compressor is formed
into an annular shape.
[0031] A first thrust bearing 35a is provided in the first recess
21c. The first thrust bearing 35a has an outer diameter of the
length D1. The first thrust bearing 35a includes a first race 351,
a second race 352, first rolling elements 353 held between the
first and second races 351, 352, and a retainer (not shown) that
retains the first rolling elements 353 between the first and second
races 351, 352. The first race 351 corresponds to the one end-side
first race in the present invention, and the second race 352
corresponds to the one end-side second race in the present
invention. The first race 351 and the second race 352 of the first
thrust bearing 35a have a thickness T1.
[0032] The first cylinder block 21 includes a first retainer groove
21e that regulates a maximum opening degree of first suction reed
valves 391a, which will be described later. Furthermore, as shown
in FIGS. 1 and 2, the first cylinder block 21 includes a first
connecting path 37a and a second front communication passage 18b.
Front ends of the first connecting path 37a and the second front
communication passage 18b open at the front end face of the first
cylinder block 21, and rear ends thereof open at the rear end face
of the first cylinder block 21.
[0033] The second cylinder block 23 is provided on the rear side of
the compressor and located between the first cylinder block 21 and
the second housing 19. The second cylinder block 23 is joined to
the first cylinder block 21, whereby a swash plate chamber 33 is
formed therebetween. The swash plate chamber 33 communicates with
the first recess 21c. Thus, the first recess 21c forms a part of
the swash plate chamber 33.
[0034] The second cylinder block 23 includes a plurality of second
cylinder bores 23a extending in the direction of the axis O of the
drive shaft 3. Similarly to the first cylinder bores 21a, the
second cylinder bores 23a are arranged at equiangular intervals in
the circumferential direction. Each of the second cylinder bores
23a is coaxially aligned with and forms a pair with the
corresponding one of the first cylinder bores 21a in the front-rear
direction. As shown in FIG. 5, the second cylinder bores 23a have a
bore diameter of the length L3. Here, the length L3 is shorter than
the length L1 shown in FIG. 4, i.e., shorter than the bore diameter
of the first cylinder bores 21a. That is, the second cylinder bores
23a have a smaller diameter than the first cylinder bores 21a. The
numbers of the first cylinder bores 21a and the second cylinder
bores 23a may be suitably selected as long as they form pairs.
Furthermore, the respective pairs of the first cylinder bores 21a
and the second cylinder bores 23a may not be aligned coaxially.
[0035] As shown in FIG. 5, the second cylinder block 23 has a
second shaft hole 23b through which the drive shaft 3 is inserted.
A second sliding bearing 22b is provided in the second shaft hole
23b. Alternatively, instead of the first sliding bearing 22a and
the second sliding bearing 22b, roller bearings may be
provided.
[0036] The second cylinder block 23 further includes a second
recess 23c that communicates with the second shaft hole 23b from
the front side of the compressor. The second recess 23c is coaxial
with the second shaft hole 23b and has an inner diameter of the
length L4, which is larger than the inner diameter of the second
shaft hole 23b. Here, the length L4, i.e., the inner diameter of
the second recess 23c, is longer than the length L2 shown in FIG.
4, i.e., the inner diameter of the first recess 21c. That is, the
second recess 23c has a larger diameter than the first recess 21c.
As shown in FIG. 5, at the rear wall of the second recess 23c, a
second recessed surface 23d that is recessed toward the rear side
of the compressor is formed into an annular shape.
[0037] A second thrust bearing 35b is provided in the second recess
23c. Similarly to the first thrust bearing 35a described above, the
second thrust bearing 35b has an outer diameter of the length D1.
The second thrust bearing 35b includes a first race 354, a second
race 355, a plurality of second rolling elements 356 held between
the first and second races 354, 355, and a retainer (not shown)
that retains the second rolling elements 356 between the first and
second races 354, 355. The first race 354 corresponds to the
opposite end-side first race in the present invention, and the
second race 355 corresponds to the opposite end-side second race in
the present invention. The first race 354 and the second race 355
of the second thrust bearing 35b also have a thickness T1. That is,
the first thrust bearing 35a shown in FIG. 4 and the second thrust
bearing 35b shown in FIG. 5 are the same in shape. Alternatively,
instead of the first and second thrust bearings 35a, 35b, other
configurations such as sliding bearings may be employed.
[0038] The second cylinder block 23 includes a second retainer
groove 23e that regulates a maximum opening degree of second
suction reed valves 411a, which will be described later.
Furthermore, as shown in FIGS. 1 and 2, the second cylinder block
23 includes an outlet port 230, a confluence discharge chamber 231,
a third front communication passage 18c, a second rear
communication passage 20b, an inlet port 330, and a second
connecting path 37b. The outlet port 230 and the confluence
discharge chamber 231 communicate with each other. Via the outlet
port 230, the confluence discharge chamber 231 is connected to a
condenser (not shown) which constitutes a refrigeration circuit.
Via the inlet port 330, the swash plate chamber 33 is connected to
an evaporator (not shown) which constitutes the refrigeration
circuit.
[0039] The third front communication passage 18c communicates with
the second front communication passage 18b and the confluence
discharge chamber 231. The front end of the second rear
communication passage 20b communicates with the confluence
discharge chamber 231, and the rear end thereof opens at the rear
end face of the second cylinder block 23. The front end of the
second connecting path 37b opens to the swash plate chamber 33, and
the rear end thereof opens at the rear end face of the second
cylinder block 23.
[0040] As shown in FIG. 4, the first valve forming plate 39 is
provided between the first housing 17 and the first cylinder block
21. The first housing 17 and the first cylinder block 21 are joined
together with the first valve forming plate 39 interposed
therebetween.
[0041] The first valve forming plate 39 includes a first valve
plate 390, a first suction valve plate 391, a first discharge valve
plate 392, and a first retainer plate 393. The first valve plate
390 and the first suction valve plate 391 extend to the outer
circumferences of the first housing 17 and the first cylinder block
21. First suction ports 390a, the number of which is the same as
that of the first cylinder bores 21a, are formed through the first
valve plate 390, the first discharge valve plate 392, and the first
retainer plate 393. First discharge ports 390b, the number of which
is the same as that of the first cylinder bores 21a, are formed
through the first valve plate 390 and the first suction valve plate
391. Furthermore, a first suction communication hole 390c is formed
through the first valve plate 390, the first suction valve plate
391, the first discharge valve plate 392, and the first retainer
plate 393. A first discharge communication hole 390d is formed
through the first valve plate 390 and the first suction valve plate
391.
[0042] The first cylinder bores 21a communicate with the first
suction chamber 27a through the respective first suction ports
390a. Also, the first cylinder bores 21a communicate with the first
discharge chamber 29a through the respective first discharge ports
390b. The first suction chamber 27a communicates with the first
connecting path 37a through the first suction communication hole
390c. The first front communication passage 18a communicates with
the second front communication passage 18b through the first
discharge communication hole 390d.
[0043] The first suction valve plate 391 is provided on the rear
surface of the first valve plate 390. The first suction valve plate
391 has the plurality of first suction reed valves 391a which are
elastically deformable to open and close the first suction ports
390a. The first discharge valve plate 392 is provided on the front
surface of the first valve plate 390. The first discharge valve
plate 392 has a plurality of first discharge reed valves 392a which
are elastically deformable to open and close the first discharge
ports 390b. The first retainer plate 393 is provided on the front
surface of the first discharge valve plate 392. The first retainer
plate 393 regulates a maximum opening degree of the first discharge
reed valves 392a.
[0044] As shown in FIG. 5, the second valve forming plate 41 is
provided between the second housing 19 and the second cylinder
block 23. The second housing 19 and the second cylinder block 23
are joined together with the second valve forming plate 41
interposed therebetween.
[0045] The second valve forming plate 41 includes a second valve
plate 410, a second suction valve plate 411, a second discharge
valve plate 412, and a second retainer plate 413. The second valve
plate 410 and the second suction valve plate 411 extend to the
outer circumferences of the second housing 19 and the second
cylinder block 23. Second suction ports 410a, the number of which
is the same as that of the second cylinder bores 23a, are formed
through the second valve plate 410, the second discharge valve
plate 412, and the second retainer plate 413. Second discharge
ports 410b, the number of which is the same as that of the second
cylinder bores 23a, are formed through the second valve plate 410
and the second suction valve plate 411. Furthermore, a second
suction communication hole 410c is formed through the second valve
plate 410, the second suction valve plate 411, the second discharge
valve plate 412, and the second retainer plate 413. A second
discharge communication hole 410d is formed through the second
valve plate 410 and the second suction valve plate 411.
[0046] The second cylinder bores 23a communicate with the second
suction chamber 27b through the respective second suction ports
410a. Also, the second cylinder bores 23a communicate with the
second discharge chamber 29b through the respective second
discharge ports 410b. The second suction chamber 27b communicates
with the second connecting path 37b through the second suction
communication hole 410c. The first rear communication passage 20a
communicates with the second rear communication passage 20b through
the second discharge communication hole 410d.
[0047] The second suction valve plate 411 is provided on the front
surface of the second valve plate 410. The second suction valve
plate 411 has the plurality of second suction reed valves 411a
which are elastically deformable to open and close the second
suction ports 410a. The second discharge valve plate 412 is
provided on the rear surface of the second valve plate 410. The
second discharge valve plate 412 has a plurality of second
discharge reed valves 412a which are elastically deformable to open
and close the second discharge ports 410b. The second retainer
plate 413 is provided on the rear surface of the second discharge
valve plate 412. The second retainer plate 413 regulates a maximum
opening degree of the second discharge reed valves 412a.
[0048] As shown in FIGS. 1 and 2, a first discharge communication
passage 18 is formed by the first front communication passage 18a,
the first discharge communication hole 390d, the second front
communication passage 18b, and the third front communication
passage 18c. Also, a second discharge communication passage 20 is
formed by the first rear communication passage 20a, the second
discharge communication hole 410d, and the second rear
communication passage 20b.
[0049] The swash plate chamber 33 communicates with the first and
second suction chambers 27a, 27b via the first and second
connecting paths 37a, 37b and the first and second suction
communication holes 390c, 410c. Thus, the pressure in the first and
second suction chambers 27a, 27b and the swash plate chamber 33 are
substantially equal. Because a low pressure refrigerant gas which
has passed through the evaporator is introduced into the swash
plate chamber 33 through the inlet port 330, the pressure in the
swash plate chamber 33 and the first and second suction chambers
27a, 27b is lower than the pressure in the first and second
discharge chambers 29a, 29b.
[0050] The drive shaft 3 includes a drive shaft body 30, a first
support member 43a, and a second support member 43b. The first
support member 43a corresponds to the first annular portion in the
present invention. The second support member 43b corresponds to the
second annular portion in the present invention.
[0051] The drive shaft body 30 extends rearward from the front side
of the housing 1 in an axial direction, i.e., along the axis O of
the drive shaft 3. A first small-diameter portion 30a is formed on
the front end side of the drive shaft body 30. A second
small-diameter portion 30b is formed on the rear end side of the
drive shaft body 30. The drive shaft body 30 is inserted through
the shaft seal device 25 and the first and second sliding bearings
22a, 22b in the housing 1. Thus, the drive shaft body 30 and
therefore the drive shaft 3 are supported in the housing 1 so as to
be rotatable about the axis O of the drive shaft 3. The front end
of the drive shaft body 30 is inserted through the shaft seal
device 25 in the boss 17a. The rear end of the drive shaft body 30
projects into the pressure regulation chamber 31.
[0052] The above-mentioned swash plate 5, the link mechanism 7, and
the actuator 13 are provided on the drive shaft body 30. The swash
plate 5, the link mechanism 7, and the actuator 13 are all disposed
in the swash plate chamber 33.
[0053] A threaded portion 3a is formed on the front end of the
drive shaft body 30. The drive shaft 3 is connected to a pulley or
an electromagnetic clutch (not shown) via the threaded portion
3a.
[0054] As shown in FIG. 4, the first support member 43a is formed
into an annular shape and its central axis coincides with the axis
O of the drive shaft 3. The first support member 43a is
press-fitted to the first small-diameter portion 30a of the drive
shaft body 30 and supported by the first sliding bearing 22a in the
first shaft hole 21b. A first flange 430 and a mounting portion
(not shown) that is configured to allow a second pin 47b, which
will be described later, to be inserted therethrough, are formed at
the rear end side of the first support member 43a.
[0055] The first thrust bearing 35a is held between the first
flange 430 and the front wall of the first recess 21c in the axial
direction. The outer diameter of the first flange 430 is larger
than the inner diameter of the first thrust bearing 35a and smaller
than the outer diameter of the first thrust bearing 35a. Thus, the
first thrust bearing 35a is in contact with the first flange 430
only in a region adjacent to the inner circumference of the second
race 352. The inner diameter of the first recessed surface 21d on
the front wall of the first recess 21c is larger than the inner
diameter of the first thrust bearing 35a and smaller than the outer
diameter of the first thrust bearing 35a. Thus, the first thrust
bearing 35a is in contact with the front wall of the first recess
21c only in a region adjacent to the outer circumference of the
first race 351.
[0056] More specifically, the first thrust bearing 35a is in
contact with the first flange 430 in the annular area E1, which is
adjacent to the inner circumference of the second race 352, and in
contact with the front surface of the first recess 21c in the
annular area E2, which is adjacent to the outer circumference of
the first race 351. That is, the region where the first thrust
bearing 35a is supported by the first support member 43a via the
first flange 430 and the region where the first thrust bearing 35a
is supported by the first cylinder block 21 via the front surface
of the first recess 21c are radially shifted from each other. In
this way, a predetermined preload is applied to the first thrust
bearing 35a, and, in the preloaded state, the first thrust bearing
35a receives a thrust force which acts on the drive shaft 3 in a
frontward direction at the time of operation of the compressor.
[0057] As shown in FIGS. 1 and 2, the front end of a first return
spring 44a is inserted in the first support member 43a. This return
spring 44a extends from a position near the first flange 430 toward
the swash plate 5 in the direction of the axis O of the drive shaft
3.
[0058] As shown in FIG. 5, the second support member 43b is formed
into an annular shape and its central axis coincides with the axis
O of the drive shaft 3. The second support member 43b is
press-fitted to the rear side of the second small-diameter portion
30b of the drive shaft body 30 and supported by the second sliding
bearing 22b in the second shaft hole 23b. A second flange 431 is
formed at the front end of the second support member 43b. The
second flange 431 has a larger diameter than the first flange 430
shown in FIG. 4.
[0059] As shown in FIG. 5, O-rings 51b, 51c are provided on the
second support member 43b at positions rearward of the second
flange 431. By providing the O-rings 51b, 51c, the pressure
regulation chamber 31 is hermetically sealed from the second recess
23c, and thus, hermetically sealed from the swash plate chamber
33.
[0060] The second thrust bearing 35b is held between the second
flange 431 and the rear wall of the second recess 23c in the axial
direction. The outer diameter of the second flange 431 is larger
than the inner diameter of the second thrust bearing 35b and
smaller than the outer diameter of the second thrust bearing 35b.
Thus, the second thrust bearing 35b is in contact with the second
flange 431 only in a region adjacent to the inner circumference of
the second race 355. The inner diameter of the second recessed
surface 23d on the rear wall of the second recess 23c is larger
than the inner diameter of the second thrust bearing 35b and
smaller than the outer diameter of the second thrust bearing 35b.
Thus, the second thrust bearing 35b is in contact with the rear
wall of the second recess 23c only in a region adjacent to the
outer circumference of the first race 354.
[0061] More specifically, the second thrust bearing 35b is in
contact with the second flange 431 in the annular area E3, which is
adjacent to the inner circumference of the second race 355, and in
contact with the rear surface of the second recess 23c in the
annular area E4, which is adjacent to the outer circumference of
the first race 354. That is, the region where the second thrust
bearing 35b is supported by the second support member 43b via the
second flange 431 and the region where the second thrust bearing
35b is supported by the second cylinder block 23 via the rear
surface of the second recess 23c are radially shifted from each
other. In this way, a predetermined preload is applied to the
second thrust bearing 35b, and in the preloaded state, the second
thrust bearing 35b receives a thrust force which acts on the drive
shaft 3 in a rearward direction at the time of operation of the
compressor.
[0062] As described above, since the first thrust bearing 35a is
held between the first flange 430 and the front surface of the
first recess 21c such that the region where the first thrust
bearing 35a is supported by the first support member 43a and the
region where the first thrust bearing 35a is supported by the first
cylinder block 21 are radially shifted from each other, the first
thrust bearing 35a is elastically deformable like a disk spring in
the axial direction. Likewise, since the second thrust bearing 35b
is held between the second flange 431 and the rear surface of the
second recess 23c such that the region where the second thrust
bearing 35b is supported by the second support member 43b and the
region where the second thrust bearing 35b is supported by the
second cylinder block 23 are radially shifted from each other, the
second thrust bearing 35b is also elastically deformable like a
disk spring in the axial direction.
[0063] In other words, in this compressor, the first spring
constant K1 of the first thrust bearing 35a is set such that the
first thrust bearing 35a is deformable in the direction of the axis
O of the drive shaft 3. Also, the second spring constant K2 of the
second thrust bearing 35b is set such that the second thrust
bearing 35b is deformable in the direction of the axis O of the
drive shaft 3. Here, as described above, the second flange 431 has
a larger diameter than the first flange 430. Therefore, the area E3
where the second race 355 of the second thrust bearing 35b is in
contact with the second flange 431 is larger than the area E1 where
the second race 352 of the first thrust bearing 35a shown in FIG. 4
is in contact with the first flange 430. That is, the region where
the second thrust bearing 35b shown in FIG. 5 is in contact with
the second flange 431 is larger than the region where the first
thrust bearing 35a shown in FIG. 4 is in contact with the first
flange 430. As a result, the second thrust bearing 35b is less
deformable in the direction of the axis O of the drive shaft 3 than
the first thrust bearing 35a. That is, in this compressor, the
second spring constant K2 of the second thrust bearing 35b is
greater than the first spring constant K1 of the first thrust
bearing 35a.
[0064] In Embodiment 1, the area E4 where the first race 354 of the
second thrust bearing 35b shown in FIG. 5 is in contact with the
rear surface of the second recess 23c is made equal to the area E2
where the first race 351 of the first thrust bearing 35a shown in
FIG. 4 is in contact with the front surface of the first recess
21c. However, the second spring constant K2 of the second thrust
bearing 35b can also be set greater than the first spring constant
K1 of the first thrust bearing 35a by making the inner diameter of
the area E4 smaller than the inner diameter of the area E2.
[0065] As shown in FIGS. 1 and 2, the swash plate 5 has a flat
annular shape and includes a front surface 5a and a rear surface
5b. The front surface 5a faces frontward of the compressor in the
swash plate chamber 33. The rear surface 5b faces rearward of the
compressor in the swash plate chamber 33.
[0066] The swash plate 5 includes a ring plate 45. The ring plate
45 has a flat annular shape with an insertion hole 45a formed in
its center. The drive shaft body 30 is inserted through the
insertion hole 45a of the swash plate 5, whereby the swash plate 5
is attached to the drive shaft 3 in the swash plate chamber 33. The
ring plate 45 has a coupling portion (not shown) to be connected to
pull arms 132, which will be described below.
[0067] The link mechanism 7 has a lug arm 49. The lug arm 49 is
disposed frontward of the swash plate 5 in the swash plate chamber
33 and located between the swash plate 5 and the first support
member 43a. The lug arm 49 is formed substantially in an L shape
from the front end toward the rear end. A weight portion 49a is
formed at the rear end of the lug arm 49. The weight portion 49a
extends in the circumferential direction of the actuator 13 over
about a half of the circumference thereof. The shape of the weight
portion 49a may be designed as appropriate.
[0068] The rear end side of the lug arm 49 is connected to the ring
plate 45 with a first pin 47a. By doing so, when the axis of the
first pin 47a is defined as a first pivot axis M1, the lug arm 49
is supported about the first pivot axis M1 so as to be pivotable
with respect to the ring plate 45, i.e., the swash plate 5. The
first pivot axis M1 extends in a direction perpendicular to the
axis O of the drive shaft 3.
[0069] The front end of the lug arm 49 is connected to the first
support member 43a with a second pin 47b. By doing so, when the
axis of the second pin 47b is defined as a second pivot axis M2,
the lug arm 49 is supported about the second pivot axis M2 so as to
be pivotable with respect to the first support member 43a, i.e.,
the drive shaft 3. The second pivot axis M2 extends parallel to the
first pivot axis M1. The lug arm 49 and the first and second pins
47a, 47b constitute the link mechanism 7 in the present
invention.
[0070] The weight portion 49a is provided so as to extend at the
rear end of the lug arm 49, i.e., on the opposite side of the
second pivot axis M2 with reference to the first pivot axis M1. As
the lug arm 49 is supported by the ring plate 45 with the first pin
47a, the weight portion 49a passes through a groove portion 45b of
the ring plate 45 and reaches the rear surface side of the ring
plate 45, i.e., the side of the rear surface 5b of the swash plate
5. Therefore, the centrifugal force generated by rotation of the
swash plate 5 about the axis O of the drive shaft 3 acts on the
weight portion 49a at the side of the rear surface 5b of the swash
plate 5.
[0071] In this compressor, the swash plate 5 is able to rotate
together with the drive shaft 3 because the swash plate 5 is
connected to the drive shaft 3 by the link mechanism 7.
Furthermore, the swash plate 5 is able to change its inclination
angle from the minimum angle shown in FIG. 1 to the maximum angle
shown in FIG. 2 because both ends of the lug arm 49 pivot about the
first pivot axis M1 and the second pivot axis M2, respectively.
[0072] As shown in FIGS. 1 and 2, the pistons 9 are double-headed
pistons, each having a first piston head 9a at its front end and a
second piston head 9b at its rear end. Since the second cylinder
bores 23a have a smaller diameter than the first cylinder bores
21a, the second piston heads 9b have a smaller diameter than the
first piston heads 9a.
[0073] The first piston heads 9a are reciprocally accommodated in
the respective first cylinder bores 21a. The first piston heads 9a
and the first valve forming plate 39 define respective first
compression chambers 53a in the respective first cylinder bores
21a. The second piston heads 9b are reciprocally accommodated in
the respective second cylinder bores 23a. The second piston heads
9b and the second valve forming plate 41 define respective second
compression chambers 53b in the respective second cylinder bores
23a.
[0074] In this compressor, the top dead center positions of the
first piston heads 9a and the second piston heads 9b moves when the
strokes of the pistons 9 changes according to the change in the
inclination angle of the swash plate 5. Specifically, as the
inclination angle of the swash plate 5 decreases, the top dead
center positions of the first and second piston heads 9a, 9b move
such that the volume of the second compression chamber 53d become
larger than the volume of the first compression chamber 51d.
[0075] The actuator 13 is disposed in the swash plate chamber 33.
More specifically, the actuator 13 is disposed rearward of the
swash plate 5 in the swash plate chamber 33, i.e., on the side of
the second cylinder block 23 with respect to the swash plate 5 in
the swash plate chamber 33, in which the second cylinder bores 23a
are formed. Accordingly, the actuator 13 is capable of advancing
into the second recess 23c.
[0076] The actuator 13 includes a movable body 13a, a partition
body 13b, and a control pressure chamber 13c. The control pressure
chamber 13c is formed between the movable body 13a and the
partition body 13b. The movable body 13a includes a rear wall 130,
a circumferential wall 131, and a pair of pull arms 132. The pull
arms 132 correspond to the connecting portion in the present
invention. In FIGS. 1 and 2, only one of the pull arms 132 is
shown.
[0077] The rear wall 130 is positioned rearward in the movable body
13a and extends radially away from the axis O of the drive shaft 3.
The rear wall 130 has an insertion hole 130a through which the
second small-diameter portion 30b of the drive shaft body 30 is
inserted. The O-ring 51d is provided in the insertion hole 130a.
The circumferential wall 131 is continuous with the outer edge of
the rear wall 130 and extends toward the front in the movable body
13a. The pull arms 132 are disposed at the front end of the
circumferential wall 131 such that the drive shaft axis O is
interposed therebetween, and project frontward in the movable body
13a. The movable body 13a has a bottomed cylindrical shape which is
formed by the rear wall 130, the circumferential wall 131, and the
pull arms 132.
[0078] The partition body 13b is formed into a disc shape having a
diameter that is substantially equal to the inner diameter of the
movable body 13a. The partition body 13b has an insertion hole 133
extending through its center. The O-ring 51e is provided on the
outer circumference of the partition body 13b.
[0079] An inclination angle reducing spring 44b is provided between
the partition body 13b and the ring plate 45. Specifically, the
rear end of the inclination angle reducing spring 44b is disposed
in contact with the partition body 13b, and the front end of the
inclination angle reducing spring 44b is disposed in contact with
the ring plate 45. The inclination angle reducing spring 44b urges
both the partition body 13b and the ring plate 45 so that they are
spaced apart from each other.
[0080] The drive shaft body 30 is inserted through the insertion
hole 130a of the movable body 13a. Thus, the movable body 13a is
movable with respect to the drive shaft body 30 along the axis O of
the drive shaft 3. On the other hand, the drive shaft body 30 is
press-fitted to the insertion hole 133 of the partition body 13b.
Thus, the partition body 13b is fixed to the drive shaft body 30 so
that the partition body 13b is rotatable together with the drive
shaft body 30. Alternatively, instead of press-fitting, the drive
shaft body 30 may be inserted through the insertion hole 133 of the
partition body 13b such that the partition body 13b is movable
along the axis O of the drive shaft 3.
[0081] The partition body 13b is disposed within the movable body
13a at a position rearward of the swash plate 5, and its outer
circumference is surrounded by the circumferential wall 131.
Consequently, when the movable body 13a moves in the direction of
the axis O of the drive shaft 3, the inner circumference of the
circumferential wall 131 of the movable body 13a slides against the
outer circumference of the partition body 13b.
[0082] The control pressure chamber 13c is formed between the
movable body 13a and the partition body 13b by surrounding the
partition body 13b with the circumferential wall 131. The control
pressure chamber 13c is partitioned from the swash plate chamber 33
by the rear wall 130, the circumferential wall 131, and the
partition body 13b.
[0083] The pull arms 132 are connected to the ring plate 45 with a
third pin 47c. When the axis of the third pin 47c is defined as an
action axis M3, the swash plate 5 is supported by the movable body
13a so as to be pivotable about the action axis M3. The action axis
M3 extends parallel to the first and second pivot axes M1, M2. In
this way, the movable body 13a is connected to the swash plate 5,
and due to this connection, the partition body 13b and the swash
plate 5 face each other.
[0084] The second small-diameter portion 30b has an axial path 3b
extending frontward from the rear end in the direction of the axis
O of the drive shaft 3, and a radial path 3c extending radially
from the front end of the axial path 3b and opening at the outer
circumferential surface of the drive shaft body 30. The rear end of
the axial path 3b communicates with the pressure regulation chamber
31. The radial path 3c communicates with the control pressure
chamber 13c. Thus, the control pressure chamber 13c communicates
with the pressure regulation chamber 31 through the radial path 3c
and the axial path 3b.
[0085] As shown in FIG. 3, the control mechanism 15 includes a
bleed passage 15a, a supply passage 15b, a control valve 15c, an
orifice 15d, the axial path 3b, and the radial path 3c.
[0086] The bleed passage 15a is connected to the pressure
regulation chamber 31 and the second suction chamber 27b. The
control pressure chamber 13c, the pressure regulation chamber 31,
and the second suction chamber 27b communicate with one another
through the bleed passage 15a, the axial path 3b, and the radial
path 3c. The supply passage 15b is connected to the pressure
regulation chamber 31 and the second discharge chamber 29b. The
control pressure chamber 13c, the pressure regulation chamber 31,
and the second discharge chamber 29b communicate with one another
through the supply passage 15b, the axial path 3b, and the radial
path 3c. The supply passage 15b has the orifice 15d.
[0087] The control valve 15c is provided in the bleed passage 15a.
The control valve 15c is capable of regulating the opening degree
of the bleed passage 15a based on the pressure in the second
suction chamber 27b.
[0088] In this compressor, the inlet port 330 shown in FIGS. 1 and
2 is connected to a pipe leading to the evaporator, and the outlet
port 230 is connected to a pipe leading to the condenser. The
condenser is connected to the evaporator through a pipe and an
expansion valve. The compressor, the evaporator, the expansion
valve, the condenser and the like constitute the refrigeration
circuit of vehicle air-conditioning apparatus. Illustration of the
evaporator, the expansion valve, the condenser and the pipes is
omitted in the drawings.
[0089] In the compressor configured as described above, the
rotation of the drive shaft 3 causes rotation of the swash plate 5,
whereby the pistons 9 reciprocate in the first cylinder bores 21a
and the second cylinder bores 23a. Therefore, the volumes of the
first and second compression chambers 53a, 53b change in response
to the piston strokes. Thus, in this compressor, the following
phases are repetitively carried out: a suction phase in which the
refrigerant gas is drawn into the first and second compression
chambers 53a, 53b; a compression phase in which the refrigerant gas
is compressed in the first and second compression chambers 53a,
53b; and a discharge phase in which the compressed refrigerant gas
is discharged into the first and second discharge chambers 29a,
29b.
[0090] The refrigerant gas discharged into the first discharge
chamber 29a flows through the first discharge communication passage
18 to the confluence discharge chamber 231. Likewise, the
refrigerant gas discharged into the second discharge chamber 29b
flows through the second discharge communication passage 20 to the
confluence discharge chamber 231. The refrigerant gas that has
reached the confluence discharge chamber 231 is discharged to the
condenser from the outlet port 230 through the pipe.
[0091] During these suction phase and the like, piston compression
forces to reduce the inclination angle of the swash plate 5 acts on
a rotational body, which consists of the swash plate 5, the ring
plate 45, the lug arm 49, and the first pin 47a. When the
inclination angle of the swash plate 5 is changed, the strokes of
the pistons 9 increase or decrease, and thereby it is possible to
control the displacement.
[0092] Specifically, in the control mechanism 15 shown in FIG. 3,
when the control valve 15c increases the opening degree of the
bleed passage 15a, the pressure in the pressure regulation chamber
31 and hence the pressure in the control pressure chamber 13c are
made to be substantially equal to the pressure in the second
suction chamber 27b. As a result, a variable differential pressure,
which is the difference in pressure between the control pressure
chamber 13c and the swash plate chamber 33, decreases. Therefore,
due to the piston compression forces acting on the swash plate 5,
the movable body 13a of the actuator 13 moves frontward in the
swash plate chamber 33 as shown in FIG. 1.
[0093] As a result, in the compressor, the swash plate 5 is urged
toward a direction to reduce the inclination angle due to the
compression reaction force, i.e., a resultant force of the piston
compression forces, which acts on the swash plate 5 via the pistons
9, and thus the movable body 13a is pulled frontward in the swash
plate chamber 33 via the pull arms 132 at the action axis M3 so
that the ring plate 45 is brought into contact with the rear end of
the return spring 44a. As the movable body 13a is pulled frontward
in the swash plate chamber 33, the swash plate 5 pivots clockwise
about the action axis M3 against the biasing force of the return
spring 44a. Furthermore, the rear end of the lug arm 49 pivots
counterclockwise about the first pivot axis M1 and the front end of
the lug arm 49 pivots counterclockwise about the second pivot axis
M2. Thus, the front end portion of the lug arm 49 approaches the
first flange 430 of the first support member 43a. With such a
configuration, the swash plate 5 pivots using the action axis M3 as
a point of action and using the first pivot axis M1 as a point of
pivot. This reduces the inclination angle of the swash plate 5 with
respect to the direction perpendicular the axis O of the drive
shaft 3 and thus decreases the strokes of the pistons 9.
Consequently, the discharge capacity of the compressor per rotation
of the drive shaft 3 decreases.
[0094] In this compressor, the centrifugal force acting on the
weight portion 49a is also imparted to the swash plate 5. As a
result, the swash plate 5 can be easily displaced in a direction to
reduce its inclination angle.
[0095] In this compressor, as the inclination angle of the swash
plate 5 becomes smaller and the strokes of the pistons 9 decrease,
the top dead center position of the second piston heads 9b moves
away from the second valve forming plate 41. As a result, when the
inclination angle of the swash plate 5 becomes nearly zero degrees,
no compression work is carried out in the second compression
chambers 53b while slight compression work is carried out in the
first compression chambers 53a.
[0096] On the other hand, in the control mechanism 15 shown in FIG.
3, when the control valve 15c reduces the opening degree of the
bleed passage 15a, the pressure in the pressure regulation chamber
31 increases due to the pressure of the refrigerant gas in the
second discharge chamber 29b, and thereby the pressure in the
control pressure chamber 13c increases. As a result, the variable
differential pressure, i.e., the difference in pressure between the
control pressure chamber 13c and the swash plate chamber 33,
increases. Therefore, against the piston compression forces acting
on the swash plate 5, the movable body 13a of the actuator 13 moves
rearward in the swash plate chamber 33 from the position shown in
FIG. 1 so as to advance into the second recess 23c as shown in FIG.
2.
[0097] Consequently, in the compressor, the movable body 13a pulls
the swash plate 5 rearward in the swash plate chamber 33 via the
pull arms 132 at the action axis M3 against the biasing force of
the inclination angle reducing spring 44b. Thus, the swash plate 5
pivots counterclockwise about the action axis M3. Furthermore, the
rear end of the lug arm 49 pivots clockwise about the first pivot
axis M1 and the front end of the lug arm 49 pivots clockwise about
the second pivot axis M2. Therefore, the front end portion of the
lug arm 49 moves rearward away from the first flange 430 of the
first support member 43a. The swash plate 5 thus pivots in a
direction opposite to the above-described direction to reduce the
inclination angle, using the action axis M3 as a point of action
and the first pivot axis M1 as a point of pivot. This increases the
inclination angle of the swash plate 5 with respect to the
direction perpendicular to the axis O of the drive shaft 3 and
increases the strokes of the pistons 9. Consequently, the discharge
capacity of the compressor per rotation of the drive shaft 3
increases.
[0098] Since this compressor has the first and second cylinder
bores 21a, 23a so that the refrigerant gas is compressed in both
the first and second compression chambers 53a, 53b, it is possible
to provide a large discharge capacity per rotation of the drive
shaft 3 as compared with the case in which the refrigerant gas is
compressed only in the first compression chambers 53a, for example.
Moreover, in this compressor, even at the time of small discharge
capacity, the compression phase for compressing the refrigerant gas
is carried out in the first compression chambers 53a, i.e., in the
first cylinder bores 21a having a larger diameter than the second
cylinder bores 23a, and therefore, it is possible to provide a
required discharge capacity.
[0099] Here, in this compressor, since the second cylinder bores
23a have a smaller diameter than the first cylinder bores 21a and
the second piston heads 9b have a smaller diameter than the first
piston heads 9a, pressure receiving area of the first piston heads
9a is larger than that of the second piston heads 9b. As a result,
as the discharge capacity increases, the thrust force toward the
rear end side of the drive shaft 3 becomes larger than the thrust
force toward the front end side of the drive shaft 3.
[0100] In this regard, in this compressor, the second flange 431
has a larger diameter than the first flange 430, and the area E3
where the second race 355 of the second thrust bearing 35b shown in
FIG. 5 is in contact with the second flange 431 is greater than the
area E1 where the second race 352 of the first thrust bearing 35a
shown in FIG. 4 is in contact with the first flange 430. Due to
this configuration, the second spring constant K2 of the second
thrust bearing 35b is greater than the first spring constant K1 of
the first thrust bearing 35a. As a result, in this compressor, even
when the thrust force toward the rear end side of the drive shaft 3
becomes larger than the thrust force toward the front end side of
the drive shaft 3 as the discharge capacity increases, it is
possible to sufficiently receive the large thrust force.
[0101] The above-described advantages of this compressor will be
described more specifically below by comparing the compressor of
Embodiment 1, the schematic diagrams of which are shown in FIGS. 7A
and 7B, with a compressor of a comparative embodiment, the
schematic diagrams of which are shown in FIGS. 6A and 6B. The
compressor of the comparative embodiment is configured such that,
unlike the compressor of Embodiment 1, the second spring constant
K22 of the second thrust bearing 35b is equal to the first spring
constant K1 of the first thrust bearing 35a. Except for this, the
features of the compressor of the comparative embodiment are the
same as those of the compressor of Embodiment 1.
[0102] As shown in FIG. 6A, in the compressor of the comparative
embodiment, when the thrust force which acts on the drive shaft 3
in the frontward direction and the thrust force which acts on the
drive shaft 3 in the rearward direction are small at the time of
small discharge capacity, the first and second thrust bearings 35a,
35b are able to support the drive shaft 3 suitably. However, as
shown in FIG. 6B, as the discharge capacity increases, the thrust
force F acting on the drive shaft 3 in the rearward direction
increases, and the second thrust bearing 35b is largely deformed in
the direction of the axis O of the drive shaft 3. If the second
thrust bearing 35b is excessively deformed in the direction of the
axis O of the drive shaft 3, the durability of the second thrust
bearing 35b is more likely to decrease.
[0103] In addition, in the case where the thrust force F acting on
the drive shaft 3 in the rearward direction causes the large
deformation of the second thrust bearing 35b in the direction of
the axis O of the drive shaft 3 and consequently the drive shaft 3
is displaced toward the rear end of the compressor by the distance
M1 from the position at the time of small discharge capacity, there
is a risk that the first thrust bearing 35a is expanded to its
limit and separated from the drive shaft 3. That is, the first
thrust bearing 35a may become unable to sufficiently support the
drive shaft 3 by elastic deformation and a gap may be created
between the drive shaft 3 and the first thrust bearing 35a. As a
result, in the compressor of the comparative embodiment, the drive
shaft 3 wobbles, and this leads to an increase of vibration and
noise caused by the vibration at the time of operation.
[0104] To solve these problems, the compressor of Embodiment 1 is
configured such that the second spring constant K2 of the second
thrust bearing 35b is greater than the first spring constant K1 of
the first thrust bearing 35a. As a result, the first and second
thrust bearings 35a, 35b are able to support the drive shaft 3
suitably not only at the time of small discharge capacity as shown
in FIG. 7A but also at the time of large discharge capacity as
shown in FIG. 7B when the thrust force F acting on the drive shaft
3 in the rearward direction is large. That is, in the compressor of
Embodiment 1, even when the thrust force F acting on the drive
shaft 3 in the rearward direction increases, the second thrust
bearing 35b is less likely to be deformed in the direction of the
axis O of the drive shaft 3. Thus, with the compressor of
Embodiment 1, it is possible to inhibit excessive deformation of
the second thrust bearing 35b in the direction of the axis O of the
drive shaft 3 as compared with the compressor of the comparative
embodiment, and therefore, it is possible to increase the
durability of the second thrust bearing 35b.
[0105] Furthermore, since the second thrust bearing 35b is less
likely to be deformed in the direction of the axis O of the drive
shaft 3, although the thrust force F acts on the drive shaft 3 in
the rearward direction, the drive shaft 3 is displaced toward the
rear end of the compressor only by the distance M2, which is
shorter than the distance M1, from the position at the time of
small discharge capacity. As a result, in the compressor of
Embodiment 1, the first thrust bearing 35a is able to sufficiently
support the drive shaft 3 without creating a gap between the drive
shaft 3 and the first thrust bearing 35a. Therefore, in the
compressor of Embodiment 1, the drive shaft 3 is less likely to
wobble even at the time of large discharge capacity.
[0106] Moreover, in the compressor of Embodiment 1, the first
spring constant K1 of the first thrust bearing 35a does not need to
be significantly large to support a large thrust force. Therefore,
drag resistances of the first and second thrust bearings 35a, 35b
acting on the drive shaft 3 do not increase excessively at the time
of small discharge capacity shown in FIG. 7A.
[0107] Therefore, the compressor of Embodiment 1 exhibits excellent
durability and inhibits vibrations and noise caused by the
vibration at the time of operation with less power loss.
[0108] In particular, in this compressor, the first thrust bearing
35a is configured such that the region where the second race 352 is
supported by the first flange 430 (i.e., the area E1) and the
region where the first race 351 is supported by the front surface
of the first recess 21c (i.e., the area E2) are radially shifted
from each other. Likewise, the second thrust bearing 35b is
configured such that the region where the second race 355 is
supported by the second flange 431 (i.e., the area E3) and the
region where the first race 354 is supported by the rear surface of
the second recess 23c (i.e., the area E4) are radially shifted from
each other.
[0109] As a result, in this compressor, both the first and second
thrust bearings 35a, 35b are elastically deformable in the
direction of the axis O of the drive shaft 3 like a disc spring.
Therefore even when the drive shaft 3 is displaced in the direction
of the axis O of the drive shaft 3 due to the thrust forces
described above, the first and second thrust bearings 35a, 35b are
able to follow the displacement suitably. Therefore, the first and
second thrust bearings 35a, 35b are able to support the drive shaft
3 suitably. Furthermore, in this compressor, the first and second
thrust bearings 35a, 35b may be provided with an interference fit,
whereby product-to-product variations of the first and second
spring constants K1 and K2 can be prevented at the time of
assembly.
[0110] Moreover, in this compressor, the area E3 where the second
race 355 of the second thrust bearing 35b is in contact with the
second flange 431 is larger than the area E1 where the second race
352 of the first thrust bearing 35a is in contact with the first
flange 430. Therefore, this compressor can be easily configured
such that the second spring constant K2 of the second thrust
bearing 35b is greater than the first spring constant K1 of the
first thrust bearing 35a while allowing both the first and second
thrust bearings 35a, 35b to be deformed in the direction of the
axis O of the drive shaft 3 as described above.
[0111] Furthermore, in this compressor, since the second cylinder
bores 23a have a smaller diameter than the first cylinder bores
21a, it is possible to configure the second recess 23c so as to
have a larger diameter than the first recess 21c without increasing
the size of the second cylinder block 23. As a result, by disposing
the actuator 13 on the side of the second cylinder block 23 with
respect to the swash plate 5 in the swash plate chamber 5, i.e., on
the side where the second cylinder bores 23a are formed, the size
of the actuator 13 can be increased without the need to increase
the size of the compressor. By doing this, the pressure receiving
area of the movable body 13a can be increased and the movable body
13a is movable with a large thrust force. Therefore, this
compressor is capable of exhibiting high controllability.
Embodiment 2
[0112] The compressor of Embodiment 2 is provided with a second
thrust bearing 35c shown in FIG. 8 in place of the second thrust
bearing 35b in the compressor of Embodiment 1. In Embodiment 2, the
second flange 431 has the same diameter as the first flange 430
(see FIG. 4).
[0113] As shown in FIG. 8, the second thrust bearing 35c has an
outer diameter of the length D1, which is the same as those of the
first and second thrust bearings 35a, 35b described above. The
second thrust bearing 35c has a first race 357, a second race 358,
a plurality of second rolling elements 359 held between the first
and second races 357, 358, and a retainer (not shown) that retains
the second rolling elements 359 between the first and second races
357, 358. The first race 357 corresponds to the opposite end-side
first race in the present invention, and the second race 358
corresponds to the opposite end-side second race in the present
invention. The second thrust bearing 35c is configured such that
the first race 357 and the second race 358 both have a thickness
T2. The thickness T2 is thicker than the thickness T1 of the first
and second races 351, 352 of the first thrust bearing 35a shown in
FIG. 4. That is, the first and second races 357, 358 of the second
thrust bearing 35c have a larger thickness than the first and
second races 351, 352 of the first thrust bearing 35a.
Alternatively, for example, only the first race 357 may have the
thickness T2 while the second race 358 may have the thickness T1 as
with the compressor of Embodiment 1.
[0114] In this compressor, similarly to the compressor of
Embodiment 1, the second thrust bearing 35c is held between the
second flange 431 and the rear wall of the second recess 23c in the
axial direction. The second thrust bearing 35c is in contact with
the second flange 431 at an annular area E5, which is adjacent to
the inner circumference of the second race 358, and in contact with
the rear surface of the second recess 23c at an annular area E4,
which is adjacent to the outer circumference of the first race 357.
That is, also in this compressor, the region where the second
thrust bearing 35c is supported by the second support member 43b
via the second flange 431 and the region where the second thrust
bearing 35c is supported by the second cylinder block 23 via the
rear surface of the second recess 23c are radially shifted from
each other. Here, as described above, the second flange 431 has the
same diameter as the first flange 430. Thus, in this compressor,
the area E5 where the second race 358 of the second thrust bearing
35b is in contact with the second flange 431 is equal to the area
E1 where the second race 352 of the first thrust bearing 35a shown
in FIG. 4 is in contact with the first flange 430. The other
features of this compressor are the same as those of the compressor
of Embodiment 1. The same reference numerals are given to the same
components and detailed description thereof is omitted.
[0115] In this compressor, the first and second races 357, 358 of
the second thrust bearing 35c have a thickness that is larger than
the thickness of the first and second races 351, 352 of the first
thrust bearing 35a. As a result, as compared with the first thrust
bearing 35a, the second thrust bearing 35c is less likely to be
elastically deformed in the direction of the axis O of the drive
shaft 3 like a disc spring. That is, also in this compressor, the
second spring constant K2 of the second thrust bearing 35c is
greater than the first spring constant K1 of the first thrust
bearing 35a. Consequently, this compressor is capable of providing
the same advantages as those of the compressor of Embodiment 1.
Embodiment 3
[0116] The compressor of Embodiment 3 is provided with a second
thrust bearing 35d shown in FIG. 9 in place of the second thrust
bearing 35b in the compressor of Embodiment 1. In this compressor,
the second flange 431 has the same diameter as the first flange 430
(see FIG. 4) as with the compressor of Embodiment 2.
[0117] As shown in FIG. 9, the second thrust bearing 35d has a
first race 361, a second race 362, a plurality of second rolling
elements 363 held between the first and second races 361, 362, and
a retainer (not shown) that retains the second rolling elements 363
between the first and second races 361, 362. The first race 361
corresponds to the opposite end-side first race in the present
invention, and the second race 362 corresponds to the opposite
end-side second race in the present invention. The second thrust
bearing 35d is configured such that the first race 361 and the
second race 362 both have a thickness T1 and thus have a thickness
equal to the thickness of the first and second races 351, 352 of
the first thrust bearing 35a shown in FIG. 4. On the other hand, as
shown in FIG. 9, the outer diameter D2 of the second thrust bearing
35d is smaller than the outer diameter D1 of the first thrust
bearing 35a. That is, the second thrust bearing 35d has a smaller
diameter than the first thrust bearing 35a.
[0118] In this compressor, similarly to the compressor of
Embodiment 1, the second thrust bearing 35d is held between the
second flange 431 and the rear wall of the second recess 23c in the
axial direction. The second thrust bearing 35d is in contact with
the second flange 431 at an annular area E5, which is adjacent to
the inner circumference of the second race 362, and in contact with
the rear surface of the second recess 23c at an annular area E6,
which is adjacent to the outer circumference of the first race 361.
That is, also in this compressor, the region where the second
thrust bearing 35d is supported by the second support member 43b
via the second flange 431 and the region where the second thrust
bearing 35d is supported by the second cylinder block 23 via the
rear surface of the second recess 23c are radially shifted from
each other. Here, as described above, the outer diameter D2 of the
second thrust bearing 35d is smaller than the outer diameter D1 of
the first thrust bearing 35a. Thus, in this compressor, the area E6
where the first race 361 of the second thrust bearing 35d is in
contact with the rear surface of the second recess 23c is smaller
than the area E2 where the first race 351 of the first thrust
bearing 35a shown in FIG. 4 is in contact with the front surface of
the first recess 21c. The other features of this compressor are the
same as those of the compressor of Embodiment 1.
[0119] In this compressor, since the outer diameter D2 of the
second thrust bearing 35d is smaller than the outer diameter D1 of
the first thrust bearing 35a, the second thrust bearing 35d is less
likely to be elastically deformed in the direction of the axis O of
the drive shaft 3 like a disc spring, as compared with the first
thrust bearing 35a. That is, also in this compressor, the second
spring constant K2 of the second thrust bearing 35d is greater than
the first spring constant K1 of the first thrust bearing 35a.
Consequently, this compressor is capable of providing the same
advantages as those of the compressor of Embodiment 1.
Embodiment 4
[0120] As shown in FIG. 10, the compressor of Embodiment 4 does not
have the second recessed surface 23d in the rear wall of the second
recess 23c unlike the compressor of Embodiment 1. Furthermore, in
Embodiment 4, the outer diameter of the second flange 431 is
substantially equal to the outer diameter of the second thrust
bearing 35b. Thus, in this compressor, the second thrust bearing
35b is held between the second flange 431 and the rear wall of the
second recess 23c in the axial direction so that the second thrust
bearing 35b is in contact with the second flange 431 over the
entire area of the second race 355. Also, the second thrust bearing
35b is in contact with the rear wall of the second recess 23c over
the entire area of the first race 354. That is, in this compressor,
the second thrust bearing 35b is provided rigidly between the
second flange 431 and the rear wall of the second recess 23c. The
other features of this compressor are the same as those of the
compressor of Embodiment 1.
[0121] In this compressor, since the second thrust bearing 35b is
provided rigidly, the second thrust bearing 35b is less likely to
be elastically deformed in the direction of the axis O of the drive
shaft 3 as compared with the first thrust bearing 35a. Therefore,
the second spring constant K2 of the second thrust bearing 35b is
greater than the first spring constant K1 of the first thrust
bearing 35a. The value of the first spring constant K1 of the first
thrust bearing 35a needs to be smaller than the value of the second
spring constant K2 of the second thrust bearing 35b. Consequently,
this compressor is capable of providing the same advantages as
those of the compressor of Embodiment 1.
[0122] Although the present invention has been described above in
line with Embodiments 1 to 4, it is needless to say that the
invention is not limited to the above-described Embodiments 1 to 4,
but may be appropriately modified and applied without departing
from the gist of the invention.
[0123] For example, a compressor may be configured by combining the
features of the compressors of Embodiments 1 to 4 as
appropriate.
[0124] Furthermore, the first thrust bearing 35a and the second
thrust bearings 35b to 35d may be made of different materials so
that the second spring constant K2 of the second thrust bearings
35b to 35d is set greater than the first spring constant K1 of the
first thrust bearing 35a.
[0125] The control mechanism 15 may be configured such that the
control valve 15c is provided in the supply passage 15b and the
orifice 15d is provided in the bleed passage 15a. In this case, the
opening degree of the supply passage 15b can be adjusted by the
control valve 15c. As a result, the pressure of the control
pressure chamber 13c can be increased rapidly due to the pressure
of the refrigerant gas in the second discharge chamber 29b, and
therefore, the discharge capacity can be increased rapidly.
* * * * *