U.S. patent application number 11/393279 was filed with the patent office on 2006-10-12 for piston type compressor.
Invention is credited to Yoshinori Inoue.
Application Number | 20060228229 11/393279 |
Document ID | / |
Family ID | 36228763 |
Filed Date | 2006-10-12 |
United States Patent
Application |
20060228229 |
Kind Code |
A1 |
Inoue; Yoshinori |
October 12, 2006 |
Piston type compressor
Abstract
A piston type compressor comprises a housing, a rotary shaft
supported by the housing, a cam mounted on the rotary shaft. The
housing includes a discharge-pressure region and a suction-pressure
region. The compressor further comprises an oil separator provided
in the discharge-pressure region and an oil reservoir for storing
lubricating oil from the oil separator. The rotary shaft has a
regulating means for regulating the axial movement of the rotary
shaft and for forming a clearance between the regulating means and
the valve plate assembly. The clearance is communicated with the
oil reservoir through a communication hole formed in the valve
plate assembly so that the clearance functions as a throttle in an
oil return passage extending from the oil separator to the inside
of the compressor. A supply passage is formed in the rotary valve
and in communication with the cam chamber in which a suction port
is provided.
Inventors: |
Inoue; Yoshinori;
(Kariya-shi, JP) |
Correspondence
Address: |
MORGAN & FINNEGAN, L.L.P.
3 World Financial Center
New York
NY
10281-2101
US
|
Family ID: |
36228763 |
Appl. No.: |
11/393279 |
Filed: |
March 29, 2006 |
Current U.S.
Class: |
417/269 |
Current CPC
Class: |
F04B 27/109 20130101;
F04B 27/1018 20130101 |
Class at
Publication: |
417/269 |
International
Class: |
F04B 27/08 20060101
F04B027/08 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 6, 2005 |
JP |
2005-110238 |
Claims
1. A piston type compressor comprising: a housing having a
plurality of cylinder bores and a cam chamber, the housing being
provided with a discharge-pressure region and a suction-pressure
region therein; a rotary shaft rotatably supported by the housing,
the cylinder bores being arranged around the rotary shaft; a cam
accommodated in the cam chamber and rotatable integrally with the
rotary shaft; a valve plate assembly provided between the cylinder
bores and the discharge-pressure region, the valve plate assembly
having a communication hole thereon; a piston accommodated in each
of the cylinder bores and operatively connected to the rotary
shaft, the piston and the valve plate assembly defining compression
chamber in the respective cylinder bore; an oil separator provided
in the discharge-pressure region for separating lubricating oil
contained in refrigerant discharged from the compression chambers;
an oil reservoir formed in the discharge-pressure region to store
the lubricating oil separated by the oil separator, the oil
reservoir being connected to the communication hole; and a
regulating means provided on the rotary shaft at an end position
close to the valve plate assembly, the regulating means and the
valve plate assembly forming a clearance in-between, wherein the
regulating means is aligned with the communication hole so that the
clearance is connected to the oil reservoir through the
communication hole.
2. The piston type compressor according to claim 1 further
comprising: a rotary valve formed integrally with the rotary shaft
and located adjacent to the valve plate assembly, the rotary valve
having a supply passage and an introducing port, the supply passage
extending axially inside the rotary valve and being in
communication with the introducing port, the introducing port being
capable of communicating with the cylinder bore in which the piston
is in suction stroke, the supply passage being open at the end
surface of the rotary valve, wherein the regulating means includes
a closure cap closing the open end of the supply passage on the
rotary valve.
3. The piston type compressor according to claim 2, wherein the cam
chamber is provided with a suction port connected to an evaporator
in an external refrigerant circuit, the cam chamber being connected
to the supply passage of the rotary valve.
4. The piston type compressor according to claim 2, wherein the
closure cap is press-fitted in the supply passage.
5. The piston type compressor according to claim 4, wherein the
closure cap includes: a cap portion press-fitted in the supply
passage; and a flange portion which extends radially from a
circumferential end of the cap portion, wherein the clearance is
formed between the flange portion and the valve plate assembly.
6. The piston type compressor according to claim 4, wherein the
closure cap includes a cylindrical and hollow cap portion
press-fitted in the supply passage.
7. The piston type compressor according to claim 1, further
comprising: a thrust bearing provided for receiving axial load of
the rotary shaft, wherein the regulating means has a surface for
receiving pressure from the oil reservoir to urge the rotary shaft
and the cam to the thrust bearing.
8. The piston type compressor according to claim 1, wherein the oil
separator is a centrifugal separator.
9. The piston type compressor according to claim 1, wherein the
compressor is of a fixed displacement type.
10. The piston type compressor according to claim 1, wherein the
clearance is a throttle for a passage between the
discharge-pressure region and the suction-pressure region.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a piston type compressor
having an oil separator for separating lubricating oil from
discharged refrigerant gas.
[0002] In a piston type compressor for a vehicle air conditioner,
lubricating oil in the form of mist is mixed with refrigerant gas
for flowing therewith within the compressor thereby to lubricate
inner parts of the compressor. In such a compressor, the oil is
contained in the discharged refrigerant gas. To prevent oil from
being carried by the refrigerant gas to an external refrigerant
circuit of the vehicle air conditioner, an oil separator is
provided in a discharge-pressure region within the compressor for
separating oil from the refrigerant gas. This is because the oil
flowing with the refrigerant gas into the external refrigerant
circuit tends to adhere to an inner wall surface of a heat
exchanger in the external refrigerant circuit thereby to
deteriorate the heat exchanging efficiency of the heat exchanger. A
typical piston type compressor having an oil separator is
disclosed, for example, in Japanese Patent Application Publication
No. 2004-218601.
[0003] The piston type compressor has such a structure in which oil
separated from refrigerant gas by the oil separator returns into
the compressor (specifically, returns into a compression chamber)
in order to keep efficient lubrication of inner parts of the
compressor. For this purpose, the oil separator and the interior of
the compressor are in communication through an oil return
passage.
[0004] The oil return passage connects the oil separator with the
compression chamber, so that there is a pressure differential
between the oil separator and the compression chamber when the oil
return passage connects the compression chamber that has just
completed the suction stroke (namely, a suction-pressure region)
with the oil separator (namely, a discharge-pressure region).
[0005] If the cross-sectional area of the oil return passage is
excessively large, not only the oil but high-pressure refrigerant
gas discharged into the oil separator would flow back into the
compression chamber and a large amount of refrigerant gas will leak
from the oil separator to the compression chamber. For this reason,
the oil return passage should be formed with an extremely small
cross-sectional area or the oil return passage should have a
throttle portion therein to provide a throttle function in the oil
return passage, thereby preventing the refrigerant gas from flowing
back.
[0006] In the structure having a throttle with an extremely small
cross-sectional area, however, foreign matters tend to clog the oil
return passage and/or the throttle portion. If the foreign, matters
clog the oil return passage and/or the throttle portion, the
quantity of lubricating oil that returns into the compressor
through the oil return passage will be decreased, with the result
that efficient lubrication of the compressor cannot be
performed.
[0007] The present invention is directed to a piston type
compressor that prevents the leakage of refrigerant gas from a
discharge-pressure region to a suction-pressure region of the
compressor and effectively returns lubricating oil to the
suction-pressure region of the compressor.
SUMMARY OF THE INVENTION
[0008] In accordance with the present invention, a piston type
compressor comprises a housing, a rotary shaft supported by the
housing, a cam mounted on the rotary shaft. The housing is formed
with a cylinder bore in which a piston is accommodated and a cam
chamber in which the cam is accommodated. The housing is further
provided with a discharge-pressure region and a suction-pressure
region therein. The compressor further comprises an oil separator
provided in the discharge-pressure region and an oil reservoir for
storing lubricating oil from the oil separator. The rotary shaft is
provided with a regulating means for regulating the axial movement
of the rotary shaft and for forming a clearance between the
regulating means and the valve plate assembly. The clearance is
communicated with the oil reservoir through a communication hole
formed in the valve plate assembly so that the clearance functions
as a throttle in an oil return passage extending from the oil
separator to the inside of the compressor. The rotary shaft may be
provided with a rotary valve. A supply passage as a suction passage
is formed in the rotary valve and in communication with the cam
chamber in which a suction port is provided to be connected to an
evaporator in an external refrigerant circuit.
[0009] Other aspects and advantages of the 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
[0010] The features of the present invention that are believed to
be novel are set forth with particularity in the appended claims.
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:
[0011] FIG. 1 is the longitudinal cross-sectional view of a piston
type compressor according to an embodiment; and
[0012] FIG. 2 is the partially enlarged cross-sectional view of a
rotary valve around a closure cap.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0013] The following will describe a preferred embodiment of a
piston type compressor according to the present invention with
reference to FIGS. 1 and 2. Note that the double-headed arrow Y1
indicates the upper and lower sides of a piston type compressor 10
and the double-headed arrow Y2 indicates the front and rear sides
of the compressor 10 in FIG. 1.
[0014] Now referring to FIG. 1, the piston type compressor 10
includes a front housing 12 and a rear housing 13 connected to the
rear end of the front housing 12. A cylinder block 11 is fixedly
connected inside the front housing 12. A valve plate assembly 14 is
interposed between the cylinder block 11 and the rear housing 13.
The cylinder block 11, the rear housing 13 and the valve plate
assembly 14 are fastened together by a plurality of bolts B (only
one bolt B shown in FIG. 1). The front housing 12 and the rear
housing 13 cooperate to form the housing assembly of the compressor
10.
[0015] The housing assembly has a discharge chamber 18 formed
between the rear housing 13 and the valve plate assembly 14 on the
radially outer side in the rear housing 13. The rear housing 13 is
provided with an oil separator S for separating lubricating oil
contained in refrigerant gas. The oil separator S is in fluid
communication with the discharge chamber 18 through a communication
port 18a. Hence, the oil separator S is located in a
discharge-pressure region of the compressor 10.
[0016] The oil separator S includes an oil separation chamber 44
and an oil separation cylinder 45 accommodated in the oil
separation chamber 44. The oil separation chamber 44 is in
communication with the discharge chamber 18 through the
communication port 18a. The communication port 18a is opened to the
oil separation chamber 44 at a position which faces the outer
peripheral surface of the oil separation cylinder 45.
[0017] The oil separator S has a discharge hole 35 formed therein
for allowing refrigerant gas from which lubricating oil has been
separated to be discharged out from the compressor 10. The
discharge chamber 18 is in communication with an external
refrigerant circuit 26 through the discharge hole 35. The external
refrigerant circuit 26 includes a condenser 27 for removing heat
from refrigerant gas, an expansion valve 28 and an evaporator 29
for transferring ambient heat in vehicle compartment to refrigerant
gas. The discharge hole 35 is in communication with the condenser
27.
[0018] An oil reservoir T is formed at the center of the rear
housing 13 between the rear housing 13 and the valve plate assembly
14. The oil reservoir T and the oil separation chamber 44 of the
oil separator S are in communication through an oil passage 32,
through which lubricating oil separated from refrigerant gas in the
oil separator S is carried into the oil reservoir T for storage
therein.
[0019] The oil reservoir T is in communication with a shaft hole
20, or the like, at the center of the cylinder block 11 through a
communication hole 46 formed in the valve plate assembly 14, so
that the lubricating oil stored in the oil reservoir T flows back
toward the cylinder block 11 through the communication hole 46.
Additionally, the valve plate assembly 14 has discharge ports 14a
and discharge valves 14b formed therein in association with the
discharge chamber 18. The discharge valves 14b are operable to open
and close the respective discharge ports 14a. In this embodiment,
the discharge chamber 18, the oil separation chamber 44, the
discharge hole 35, the oil reservoir T and the compression chamber
34 in discharge stroke form the discharge-pressure region of the
compressor 10.
[0020] A crank chamber 17, which serves as a cam chamber, is
defined between the front housing 12 and the cylinder block 11. A
rotary shaft 19 is rotatably supported in the crank chamber 17 by
the cylinder block 11 and the front housing 12. The rotary shaft 19
is inserted at one end thereof into the shaft hole 20 formed in the
cylinder block 11 and at the other end thereof into a shaft hole 21
formed in the front housing 12. The shaft hole 20 is located in
alignment with the oil reservoir T through the valve plate assembly
14, and the communication hole 46 adjacent to the cylinder block 11
is opened to the shaft hole 20.
[0021] The rotary shaft 19 is supported at its front side by the
front housing 12 through a radial bearing 22 placed in the shaft
hole 21. The rotary shaft 19 is directly supported at its rear side
by the cylinder block 11 through a peripheral sealing surface 20a
formed on the inner peripheral surface of the shaft hole 20. Thus,
the communication hole 46 adjacent to the cylinder block 11 is
opened to the rear end of the rotary shaft 19. The radial bearing
22 and the peripheral sealing surface 20a of the shaft hole 20
receive radial loads on the front and rear sides of the rotary
shaft 19, respectively. A shaft seal 23 of a lip seal type is
interposed between the front housing 12 and the rotary shaft
19.
[0022] A swash plate 24 which serves as a cam is secured on the
rotary shaft 19 within the crank chamber 17. The swash plate 24 has
at its boss portion 24a an inserting hole 24b which is formed along
the axis of the swash plate 24 (that is, along the axis L of the
rotary shaft 19), and the rotary shaft 19 is press-fitted in the
inserting hole 24b.
[0023] The crank chamber 17 is in communication with the evaporator
29 in the external refrigerant circuit 26 through a suction hole 25
formed in the front housing 12. Refrigerant gas, which is
discharged into the discharge chamber 18 and the lubricating oil
separated therefrom at the oil separator S, flows into the
condenser 27 in the external refrigerant circuit 26 through a
discharge hole 35 adjacent to the oil separator S. After passing
through the expansion valve 28 and the evaporator 29, refrigerant
gas flows into the crank chamber 17 through the suction hole 25.
The shaft seal 23 prevents the leakage of refrigerant gas through a
clearance between the peripheral surface of the rotary shaft 19 and
the front housing 12. A thrust bearing 30 is interposed between the
front housing 12 and the boss portion 24a of the swash plate 24 for
receiving an axial load (or thrust load) of the rotary shaft
19.
[0024] A plurality of cylinder bores 11a (five cylinder bores in
this embodiment but only one being shown in FIG. 1) are formed in
the cylinder block 11 around the rotary shaft 19. Each of the
cylinder bores 11a is closed by the valve plate assembly 14 and
accommodates therein a reciprocally slidable single-headed piston
31. Each piston 31 slidably engages with the periphery of the swash
plate 24 through a pair of shoes 33a, 33b.
[0025] The rotation of the swash plate 24 with the rotary shaft 19
is converted into the reciprocal movement of the pistons 31 in the
cylinder bore 11a through the shoes 33a, 33b. In other words, the
pistons 31 are operatively associated with the rotation of the
rotary shaft 19 through the swash plate 24 secured to the rotary
shaft 19. The pistons 31 and the valve plate assembly 14 define
compression chambers 34 in the respective cylinder bores 11a. The
shaft hole 20 of the cylinder block 11 surrounded by the cylinder
bores 11a serves also as a valve chamber. The shaft hole 20 and the
compression chambers 34 (cylinder bores 11a) are in communication
with each other through respective suction ports 36 formed in the
cylinder block 11. Each suction port 36 has an inlet 36a opened at
the peripheral sealing surface 20a of the shaft hole 20 and an
outlet 36b opened at the inner peripheral surface of the cylinder
bore 11a.
[0026] As mentioned earlier, the rotary shaft 19 is rotatably
received at the rear end thereof (or the side thereof adjacent to
the valve plate assembly 14) in the shaft hole 20. The rotary shaft
19 has a supply passage 41 extending axially from the thrust
bearing 30 to the rear end of the rotary shaft 19. An introducing
hole 42 extends through the boss portion 24a of the swash plate 24
and the rotary shaft 19 for fluid communication between the supply
passage 41 and the crank chamber 17. That is, the introducing hole
42 permits refrigerant gas in the crank chamber 17 to flow into the
supply passage 41.
[0027] An introducing port 43 is formed in the rotary shaft 19
adjacent to the valve plate assembly 14 for communication with the
supply passage 41. The introducing port 43 has an inlet 43a which
is opened at the inner peripheral surface of the rotary shaft 19
and an outlet 43b which is opened at the outer peripheral surface
of the rotary shaft 19. As the rotary shaft 19 is rotated in
operation of the compressor 10, the outlet 43b of the introducing
port 43 communicates intermittently with the inlet 36a of the
suction port 36. The supply passage 41, the introducing hole 42 and
the introducing port 43 in the rotary shaft 19 are provided to
introduce refrigerant gas from the crank chamber 17 into the
compression chamber 34. The rear portion of the rotary shaft 19
which is surrounded by the peripheral sealing surface 20a of the
shaft hole 20 functions as a rotary valve 50 formed integrally with
the rotary shaft 19 adjacent to the valve plate assembly 14. In
this embodiment, the crank chamber 17, the shaft hole 20, the
supply passage 41 and the compression chamber 34 in suction stroke
form a suction-pressure region of the compressor 10.
[0028] In the above compressor 10, during the suction stroke of the
piston 31 (or the stroke when the piston 31 moves frontward), the
inlet 36a of the suction port 36, which communicates with the
cylinder bore 11a, communicates with the outlet 43b of the
introducing port 43. Therefore, refrigerant gas in the supply
passage 41 of the rotary shaft 19 is drawn into the compression
chamber 34 in the cylinder bore 11a through the introducing port 43
and the suction port 36.
[0029] On the other hand, during the discharge stroke of the piston
31 (or the stroke when the piston 31 moves rearward), communication
between the inlet 36a of the suction port 36 that communicates with
the cylinder bore 11a and the outlet 43b of the introducing port 43
is shut off. Thus, refrigerant gas in the compression chamber 34 is
discharged into the discharge chamber 18 through the discharge port
14a while pushing and opening the discharge valve 14b. Refrigerant
gas thus discharged into the discharge chamber 18 flows into the
oil separator S and then further flows to the external refrigerant
circuit 26 through the discharge hole 35 of the separator S.
Refrigerant that flows out to the external refrigerant circuit 26
returns to the crank chamber 17 of the compressor 10 afterward.
[0030] Referring to FIG. 2, the rotary valve 50 has an opening at
its rear end. A closure cap 51, which serves a closure means, is
fitted to the rear end of the rotary valve 50 at a position that is
closer to the valve plate assembly 14 than the introducing port 43.
This closure cap 51 includes a cylindrical and hollow cap portion
52 and a flange portion 53. The flange portion 53 extends radially
from the rear end periphery of the cap portion 52. The flange
portion 53 extends all around the cap portion 52. The closure cap
51 is fitted in the rotary valve 50 by the portion 52 press-fitted
into the supply passage 41. The closure cap 51 is rotatable with
the rotary valve 50. With the cap portion 52 fitted in the supply
passage 41, the flange portion 53 covers the entire end face of the
rotary valve 50 (or the rotary shaft 19).
[0031] The length of the cap portion 52 in the axial direction of
the closure cap 51 is slightly shorter than the distance from the
rear end of the rotary valve 50 to the introducing port 43. In
other words, the introducing port 43 is not closed by the cap
portion 52. In addition, the diameter of the cap portion 52 is
slightly greater than the inner diameter of the rotary valve 50
(that is, the inner diameter of the rotary shaft 19 or the diameter
of the supply passage 41).
[0032] Therefore, with the closure cap 51 fitted in the rotary
valve 50, the cap portion 52 closes the supply passage 41 and is
pressed against the peripheral surface of the supply passage 41 (or
the inner peripheral surface of the rotary shaft 19) thereby to
form a sealing surface 55. In other words, the cap portion 52 seals
to prevent the leakage of refrigerant gas through the rear end of
the rotary valve 50 from the supply passage 41.
[0033] A clearance CL is formed between the valve plate assembly 14
and the end face 53a of the flange portion 53 adjacent to the valve
plate assembly, as shown in FIG. 2. This clearance CL is provided
to prevent sliding contact between the closure cap 51 and the valve
plate assembly 14 during operation of the piston type compressor
10.
[0034] The closure cap 51 also functions as a regulating means for
regulating the axial sliding movement of the rotary shaft 19 to a
specified amount. The rotary shaft 19 is movable slightly in its
axial direction though this axial sliding movement of the rotary
shaft 19 in forward direction is so regulated that the boss portion
24a of the swash plate 24 contacts with the thrust bearing 30. When
the compressor 10 is stopped (e.g. when a clutch for transmitting
power from a drive source to the rotary shaft 19 is just
disengaged), the compression reaction force that acts on the
pistons 31 from the compression chambers 34 is decreased rapidly,
so that the rotary shaft 19 tends to slide axially rearward.
However, such axial sliding movement of the rotary shaft 19 in a
rearward direction is regulated by the end face 53a of the flange
portion 53 of the closure cap 51 to be brought into contact with
the valve plate assembly 14.
[0035] Depending on the depth of press-fitting of the portion 52 of
the closure cap 51 into the supply passage 41 or the thickness of
the flange portion 53, the clearance CL between the end face 53a
and the valve plate assembly 14 may be adjusted. By the clearance
CL so adjusted, the axial sliding movement of the rotary shaft 19
may be regulated to any desired amount. Note that the clearance CL
should preferably be as small as possible to prevent the leakage of
refrigerant gas. In this embodiment, the clearance CL is formed
with a cross-sectional area smaller than the communication hole
46.
[0036] The communication hole 46 is formed in the valve plate
assembly 14 for providing communication between the oil reservoir T
and the clearance CL. That is, the communication hole 46 is opened
at one end thereof to the oil reservoir T and at the other end to
the clearance CL. The clearance CL is in communication with the
communication hole 46 and has a smaller cross-sectional area than
the communication hole 46, so that it functions as a throttle to
prevent the refrigerant gas from flowing back from the oil
separator S through the oil passage 32, the oil reservoir T and the
communication hole 46. The end face 53a of the flange portion 53
and the inner surface 52a of the cap portion 52 (or the end face
thereof adjacent to the valve plate assembly 14) cooperate to form
a surface receiving back pressure from the oil reservoir T.
[0037] In operation of the above-described piston type compressor
10, refrigerant gas discharged from the compression chamber 34 into
the discharge chamber 18 then flows into the oil separator S
through the communication port 18a. Refrigerant gas introduced into
the oil separation chamber 44 in the oil separator S is whirled in
the space between the inner peripheral surface of the oil
separation chamber 44 and the outer peripheral surface of the oil
separations cylinder 45, and the lubricating oil contained in the
refrigerant gas is separated therefrom under the influence of
centrifugal force. Refrigerant gas the lubricating oil is separated
therefrom flows into the oil separation cylinder 45 through the
bottom opening thereof and then flows out to the external
refrigerant circuit 26 (specifically, to the condenser 27) through
the discharge hole 35 formed at the top of the oil separation
cylinder 45.
[0038] On the other hand, lubricating oil separated from
refrigerant gas in the oil separation chamber 44 is conveyed to the
oil reservoir T through the oil passage 32. Furthermore,
lubricating oil stored in the oil reservoir T is supplied to the
shaft hole 20 through the communication hole 46. In other words,
lubricating oil separated from refrigerant gas returns to the shaft
hole 20 from the oil separator S.
[0039] The oil separator S and the shaft hole 20 are in
communication through the oil passage 32, the oil reservoir T and
the communication hole 46. The communication hole 46 communicates
with the clearance CL, which functions as a throttle for the oil
return passage extending from the oil separator S to the inner side
of the compressor 10. Therefore, high-pressure refrigerant gas in
the oil separator S is prevented from leaking in large amount into
the low-pressure shaft hole 20 which forms a part of a
suction-pressure region of the compressor 10.
[0040] The closure cap 51 which rotates integrally with the rotary
valve 50 prevents the clearance CL from being clogged with foreign
matters, thereby maintaining the clearance CL for constant
communication between the hole 46 and the shaft hole 20.
Accordingly, there will not occur a trouble that the clearance CL
clogs thereby to block the flow of lubricating oil returning from
the oil separator S to the shaft hole 20. Thus, lubricating oil
returned to the shaft hole 20 through the clearance CL is supplied
between the outer peripheral surface 50a of the rotary valve 50 and
the peripheral sealing surface 20a and further supplied into the
crank chamber 17 along the rotary shaft 19. As a result,
lubricating oil circulates in the compressor 10, thus ensuring
lubrication of its parts.
[0041] In addition, when lubricating oil returns from the oil
reservoir T to the shaft hole 20 through the communication hole 46,
high pressure is applied to the end face 53a of the flange portion
53 and the inner surface 52a of the cap portion 52 in the frontward
axial direction. As the closure cap 51 is subjected to such back
pressure at the end face 53a and the inner surface 52a, the rotary
shaft 19 to which the closure cap 51 is fitted is urged axially
forward by the back pressure, that is, toward the crank chamber
17.
[0042] Subsequently, the swash plate 24 secured to the rotary shaft
19 is also urged forward in the axial direction of the rotary shaft
19, and its front surface of the boss portion 24a is entirely
pressed against the thrust bearing 30. Urging the swash plate 24
against the thrust bearing 30 prevents the swash plate 24 from
being inclined by compression reaction force via the pistons 31,
otherwise the front face of the swash plate boss portion 24a would
be inclined by the reaction force with respect to the thrust
bearing 30, perpendicular to the axis of the rotary shaft 19. This
ensures the entire circumferential contact between the front
surface of the swash plate boss portion 24a and the thrust bearing
30, and prevents their partial contact.
[0043] According to the preferred embodiment, the following
advantageous effects are obtained.
[0044] (1) The clearance CL which is formed between the valve plate
assembly 14 and the end of the closure cap 51 adjacent to the valve
plate assembly 14 is in communication with the oil reservoir T
through the communication hole 46. The clearance CL functions as a
throttle for the oil return passage which extends from the oil
separator S, the discharge-pressure region, to the shaft hole 46,
the suction-pressure region. Thus, the clearance CL restricts
refrigerant gas in the oil separator S to flow back to the shaft
hole 20, thereby preventing a large amount of refrigerant gas from
leaking from the discharge-pressure region to the suction-pressure
region.
[0045] In addition, the closure cap 51 rotates integrally with the
rotary valve 50 (or the rotary shaft 19), so that the closure cap
51 which forms the clearance CL rotates relatively to the valve
plate assembly 14. As a result, the clearance CL will not be
clogged with any foreign matters may be contained in lubricating
oil and/or refrigerant gas. This keeps the clearance CL free from
blockage and ensures lubricating oil to return smoothly from the
oil reservoir T through the communication hole 46, thus appropriate
lubrication within the compressor 10 is obtained.
[0046] (2) The clearance CL is formed between the closure cap 51
and the valve plate assembly 14 for allowing the slight axial
movement of the rotary shaft 19. This clearance CL is utilized as a
throttle for the oil return passage from the oil separator S. Thus,
the preferred embodiment provides a structure made in a similar way
for preventing the leakage of refrigerant gas from the
discharge-pressure region to the suction-pressure region, compared
to, for example, the cross-sectional area of the communication hole
46 made small for the same purpose.
[0047] (3) The oil reservoir T and the shaft hole 20 are made in
communication with each other through the communication hole 46 so
that lubricating oil in the oil reservoir T returns to the shaft
hole 20 (suction-pressure region) through the communication hole
46. Thus, back pressure in the oil reservoir T may be applied to
the inner surface 52a of the cap portion 52 and the end face 53a of
the flange portion 53. With the closure cap 51 subjected to the
back pressure, the rear end of the rotary shaft 19 is urged toward
the crank chamber 17. As a result, the swash plate 24 is pressed at
the entire side surface of the boss portion 24a thereof against the
thrust bearing 30. Accordingly, the swash plate 24 is prevented
from being inclined with respect to the thrust bearing 30 by
compression reaction force acting on the pistons 31. This prevents
the front face of the swash plate boss portion 24a from partially
pressing and contacting to the thrust bearing 30. Hence, rattling
of the rotary shaft 19 causing the above partial press and contact
between the swash plate 24 and the thrust bearing 30 is reduced,
thereby preventing generation of noise and vibration.
(4) The clearance CL is supplied and filled with lubricating oil
from the oil reservoir T. Thus, leakage of refrigerant gas through
the clearance CL is prevented.
[0048] (5) Means for closing the supply passage 41 of the rotary
valve 50 is provided as the closure cap 51 which is press-fitted in
the supply passage 41. The closure cap 51 is simply fitted to the
rotary valve 50 merely by press-fitting it into the supply passage
41. This simplifies the process of assembling the compressor
10.
[0049] (6) The closure cap 51 includes the cap portion 52 and the
flange portion 53. When the portion 52 of the closure cap 51 is
press-fitted in the supply passage 41, the flange portion 53 may
contact with the axial rear end of the rotary valve 50 in order to
limit its further press-fitting into the supply passage 41 for the
clearance CL not so enlarged.
[0050] (7) The closure cap 51 to receive the back pressure but also
to serve as a regulating member for regulating the axial
displacement of the rotary shaft 19. This simplifies the structure
of the compressor 10 in comparison to a structure in which
components for respective functions are provided individually.
[0051] The present invention is not limited to the above-described
embodiment but it may be modified into various alternative
embodiments as exemplified below.
[0052] In an alternative embodiment, the cap portion 52 is not
limited to a hollow structure, but it may be of solid provided that
the cap portion 52 press-fitted in a position closes the supply
passage 41.
[0053] In an alternative embodiment, if the cap portion 52
press-fitted in a position is prevented from moving further into
the supply passage 41, the closure cap 51 may be formed only by the
cap portion 52 without the flange portion 53.
[0054] In an alternative embodiment, the present invention is also
applicable to a piston type compressor equipped with a cam having a
shape other than that of the swash plate 24.
[0055] In an alternative embodiment, the oil separator S is not
limited to a centrifugal separator, but it may be, for example, an
inertial separator for separating lubricating oil from refrigerant
gas by allowing the refrigerant gas to collide against a wall
surface.
[0056] In an alternative embodiment, a filter may be provided in
the oil reservoir T.
[0057] In an alternative embodiment, a cylindrical valve body
having a bottom at one end may be fitted in the inserting hole 24b
of the swash plate 24 for forming the rotary valve 50. In this
case, the bottom of the valve body closes the supply passage 41,
and the clearance CL is formed between the bottom and the valve
plate assembly 14. In other words, the bottom of the valve body may
serve as a closure means, a pressure receiving surface and a
regulating means.
[0058] 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 of the appended claims.
* * * * *