U.S. patent application number 11/657296 was filed with the patent office on 2007-08-02 for structure for oil recovery in a compressor.
Invention is credited to Yoshinori Inoue, Akinobu Kanai, Osamu Nakayama, Tomoji Tarutani.
Application Number | 20070177988 11/657296 |
Document ID | / |
Family ID | 37944703 |
Filed Date | 2007-08-02 |
United States Patent
Application |
20070177988 |
Kind Code |
A1 |
Inoue; Yoshinori ; et
al. |
August 2, 2007 |
Structure for oil recovery in a compressor
Abstract
In a structure for oil recovery in a compressor for separating
oil from refrigerant and supplying the separated oil into the
compressor through an oil supply passage, the compressor includes a
rotary shaft, a cylinder block having a plural cylinder bores, a
cam member rotated integrally with the rotary shaft, a piston
received in each cylinder bore being operable in conjunction with
the rotation of the rotary shaft through the cam member, a suction
port for allowing the refrigerant to be drawn from a
suction-pressure region of the compressor to the corresponding
cylinder bore, a discharge port for allowing the refrigerant to be
discharged from the corresponding cylinder bore to a
discharge-pressure region of the compressor, and a flexible reed
valve for opening and closing one of the suction port and the
discharge port. The oil supply passage is opened and closed in
accordance with motion of the reed valve.
Inventors: |
Inoue; Yoshinori;
(Kariya-shi, JP) ; Nakayama; Osamu; (Kariya-shi,
JP) ; Kanai; Akinobu; (Kariya-shi, JP) ;
Tarutani; Tomoji; (Kariya-shi, JP) |
Correspondence
Address: |
MORGAN & FINNEGAN, L.L.P.
3 World Financial Center
New York
NY
10281-2101
US
|
Family ID: |
37944703 |
Appl. No.: |
11/657296 |
Filed: |
January 23, 2007 |
Current U.S.
Class: |
417/269 ;
417/313 |
Current CPC
Class: |
F04B 39/16 20130101;
F04B 27/109 20130101 |
Class at
Publication: |
417/269 ;
417/313 |
International
Class: |
F04B 27/08 20060101
F04B027/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 23, 2006 |
JP |
P2006-013691 |
Claims
1. A structure for oil recovery in a compressor for separating oil
from refrigerant and supplying the separated oil into the
compressor, comprising: a rotary shaft; a cylinder block having a
plurality of cylinder bores formed therethrough to be arranged
around the rotary shaft; a cam member rotated integrally with the
rotary shaft; a piston received in each cylinder bore being
operable in conjunction with the rotation of the rotary shaft
through the cam member; a suction port for allowing the refrigerant
to be drawn from a suction-pressure region of the compressor to the
corresponding cylinder bore; a discharge port for allowing the
refrigerant to be discharged from the corresponding cylinder bore
to a discharge-pressure region of the compressor; a flexible reed
valve for opening and closing one of the suction port and the
discharge port; and an oil supply passage for allowing the oil to
be supplied into the compressor, wherein the oil supply passage is
opened and closed in accordance with motion of the reed valve.
2. The structure according to claim 1, wherein the cylinder bores
are separated from the suction-pressure region and the
discharge-pressure region by a partition plate, the reed valve
being movable away from or toward and into contact with a face of
the partition plate adjacent to the cylinder bores to open or close
the corresponding suction port, an outlet of the oil supply passage
being covered by the reed valve when the reed valve closes the
suction port.
3. The structure according to claim 2, wherein the outlet of the
oil supply passage is divided into two parts which are formed on
each side of the reed valve adjacent to the proximal side
thereof.
4. The structure according to claim 2, wherein the oil supply
passage includes an annular passage which is formed so as to
encompass all the cylinder bores, the annular passage being
connected to the outlet through an oil supply groove.
5. The structure according to claim 2, wherein the oil supply
passage includes an annular passage which is formed so as to
entirely surround an axis of the rotary shaft, the annular passage
being connected to the outlet through an oil supply groove.
6. The structure according to claim 5, wherein the oil supply
groove is radially formed in the face of the partition plate.
7. The structure according to claim 5, wherein the annular passage
is formed in the partition plate.
8. The structure according to claim 1, wherein the cylinder bores
are separated from the suction-pressure region and the
discharge-pressure region by a partition plate, the reed valve
being movable away from or toward and into contact with a face of
the partition plate on the opposite side to the cylinder bores to
open or close the corresponding discharge port, a part of the oil
supply passage being provided in the partition plate, a shutter
being operable to open and close the part of the oil supply passage
provided in the partition plate in conjunction with the motion of
the reed valve.
9. The structure according to claim 1, wherein the oil in the oil
supply passage is directly supplied into the plural cylinder bores.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a structure for oil
recovery in a compressor.
[0002] Japanese Patent Application Publication No. 2001-173563
discloses a compressor wherein a rotary body is mounted on a drive
shaft of the compressor for rotation therewith adjacent to a radial
bearing. The rotary body is rotatably fitted in a circular hole
formed in a cylinder block of the compressor and a groove is formed
in the outer peripheral surface of the rotary body. Lubricating oil
is separated from refrigerant in the discharge-pressure region of
the compressor by an oil separator, and is supplied through an oil
supply hole into a gap between the outer peripheral surface of the
rotary body and the inner peripheral surface of the circular hole.
In the meantime, the above gap is in communication with a drive
chamber through a bleed hole. The groove is communicable with the
oil supply hole and the bleed hole alternately one time for each
rotation of the drive shaft. When the groove is connected with the
oil supply hole, the oil is supplied into the groove. When the
groove into which the oil is supplied is then connected with the
bleed hole, the oil in the groove is supplied into the drive
chamber through the bleed hole thereby to lubricate parts or
elements in the drive chamber which need to be lubricated.
[0003] The gap between the outer peripheral surface of the rotary
body and the inner peripheral surface of the circular hole is
necessary for allowing the rotary body to rotate. In addition, an
oil separation chamber in which the oil separator is disposed is a
part of the discharge-pressure region of the compressor and the
drive chamber is lower in pressure than the discharge-pressure
region. Therefore, the above separated oil constantly leaks into
the drive chamber through the gap between the outer peripheral
surface of the rotary body and the inner peripheral surface of the
circular hole because of the pressure differential between the
drive chamber and the oil separation chamber. Such leakage may
cause the oil reserved at the bottom of the oil separation chamber
to be drained.
[0004] The present invention is directed to a structure for oil
recovery in a compressor which can prevent the oil separated from
the refrigerant from being drained.
SUMMARY OF THE INVENTION
[0005] An aspect of the present invention provides a structure for
oil recovery in a compressor for separating oil from refrigerant
and supplying the separated oil into the compressor through an oil
supply passage. The compressor includes a rotary shaft, a cylinder
block having a plurality of cylinder bores formed therethrough to
be arranged around the rotary shaft, a cam member rotated
integrally with the rotary shaft, a piston received in each
cylinder bore being operable in conjunction with the rotation of
the rotary shaft through the cam member, a suction port for
allowing the refrigerant to be drawn from a suction-pressure region
of the compressor to the corresponding cylinder bore, a discharge
port for allowing the refrigerant to be discharged from the
corresponding cylinder bore to a discharge-pressure region of the
compressor, and a flexible reed valve for opening and closing one
of the suction port and the discharge port. The oil supply passage
is opened and closed in accordance with motion of the reed
valve.
[0006] 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
[0007] 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:
[0008] FIG. 1A is a longitudinal sectional view showing a variable
displacement compressor according to a first embodiment of the
present invention;
[0009] FIG. 1B is a partially enlarged view of FIG. 1A;
[0010] FIG. 2A is a cross sectional view as seen from the line A-A
of FIG. 1A;
[0011] FIG. 2B is a partially enlarged longitudinal sectional view
as seen from the line C-C of FIG. 2A;
[0012] FIG. 3 is a partially enlarged view of FIG. 1A;
[0013] FIG. 4 is a cross sectional view as seen from the line B-B
of FIG. 1A;
[0014] FIG. 5 is a partially enlarged view of FIG. 4;
[0015] FIG. 6 is a partially enlarged cross sectional view showing
a variable displacement compressor according to a second embodiment
of the present invention;
[0016] FIG. 7 is a longitudinal sectional view showing a fixed
displacement compressor according to a third embodiment of the
present invention;
[0017] FIG. 8 is a cross sectional view as seen from the line D-D
of FIG. 7;
[0018] FIG. 9A is a partially enlarged view of FIG. 7; and
[0019] FIG. 9B is a partially enlarged view of FIG. 7.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] The following will describe a first embodiment of an oil
recovery structure according to the present invention as applied to
a variable displacement compressor with reference to FIGS. 1A
through 5. Referring firstly to FIG. 1A, the variable displacement
compressor designated generally by numeral 10 includes a cylinder
block 11 and a front housing 12 which is joined to the front end of
the cylinder block 11. A rear housing 13 is fixedly joined to the
rear end of the cylinder block 11 through a valve plate 14, a
suction valve plate 15, a discharge valve plate 16 and a retainer
plate 17. The cylinder block 11, the front housing 12 and the rear
housing 13 cooperate to form a housing of the variable displacement
compressor 10.
[0021] A rotary shaft 18 is rotatably supported by the front
housing 12 and the cylinder block 11 through radial bearings 25,
26, respectively. As shown in FIG. 1A, the front housing 12 and the
cylinder block 11 cooperate to form a pressure control chamber 121.
A rotary support 19 is fixedly mounted on the rotary shaft 18, and
a swash plate 20 is supported by the rotary shaft 18 in such a way
that it is slidable in the direction of the axis 181 of the rotary
shaft 18 and also inclinable relative to the axis 181. A pair of
connecting elements 21 (only one being shown in FIG. 1A) is fixedly
mounted on the swash plate 20 that serves as a cam member. A guide
pin 22 (only one being shown in FIG. 1A) is fixedly mounted on each
connecting element 21. A pair of guide holes 191 (only one being
shown in FIG. 1A) is formed in the rotary support 19. The heads of
the guide pins 22 are slidably fitted in the guide holes 191. The
swash plate 20 is inclinable relative to the axis 181 of the rotary
shaft 18 and rotatable integrally with the rotary shaft 18 through
the connection between the paired guide holes 191 and the paired
guide pins 22. The inclination of the swash plate 20 is guided by
the guide holes 191 receiving therein the guide pins 22 and the
rotary shaft 18 slidably supporting the swash plate 20.
[0022] In operation of the compressor 10, as the center of the
swash plate 20 adjacent to the rotary shaft 18 moves toward the
rotary support 19, the inclination of the swash plate 20 increases.
The maximum inclination of the swash plate 20 is restricted by the
contact between the rotary support 19 and the swash plate 20. The
swash plate 20 of FIG. 1A which is indicated by solid line is at
the position of the maximum inclination of the swash plate 20. As
the center of the swash plate 20 moves toward the cylinder block
11, the inclination of the swash plate 20 decreases. The swash
plate 20 of FIG. 1A which is indicated by two-dot chain line is at
the position of the minimum inclination of the swash plate 20.
[0023] The cylinder block 11 has formed therethrough a plurality of
cylinder bores 111, each of which receives therein a piston 23. The
rotary motion of the swash plate 20 is converted into the
reciprocating motion of each piston 23 in its corresponding
cylinder bore 111 through a pair of shoes 24.
[0024] As shown in FIGS. 1A and 2A, the rear housing 13 has a
suction chamber 131 and a discharge chamber 132 formed therein. The
cylinder bores 111 are separated from the suction chamber 131 and
the discharge chamber 132 by the valve plate 14. The suction
chamber 131 forms a part of the suction-pressure region of the
compressor 10 and the discharge chamber 132 forms a part of the
discharge-pressure region of the compressor 10.
[0025] As shown in FIG. 2B, the valve plate 14 and the discharge
valve plate 16 have suction ports 141 formed therethrough. The
valve plate 14 and the suction valve plate 15 have discharge ports
142 formed therethrough. The valve plate 14 serves as a partition
plate of the present invention. The suction valve plate 15 has
flexible plate-like suction valves 151 and the discharge valve
plate 16 has flexible plate-like discharge valves 161.
[0026] During the suction stroke of the piston 23 moving leftward
as seen in FIG. 1A, refrigerant gas in the suction chamber 131 is
drawn through the suction valve 151 (or reed valve) into the
cylinder bore 111 corresponding to the piston 23 in the suction
stroke. The refrigerant gas drawn into the cylinder bore 111 is
then compressed by the piston 23 moving rightward in FIG. 1A and
discharged into the discharge chamber 132 while pushing open the
discharge valve 161 (or reed valve). The pressure in the cylinder
bore 111 varies between the suction pressure and the discharge
pressure in accordance with the reciprocating motion of the piston
23.
[0027] As shown in FIG. 2B, the suction valve 151 is movable away
from or toward and into contact with the front face 143 of the
valve plate 14 adjacent to the cylinder bore 111 thereby to open or
close the suction port 141. The discharge valve 161 is movable away
from or toward and into contact with the rear face 144 of the valve
plate 14 on the side opposite to the cylinder bore 111 thereby to
open or close the discharge port 142. The discharge valve 161 is
brought into contact with a retainer 171 of a retainer plate 17 for
restricting the opening of the discharge valve 161.
[0028] As shown in FIG. 1A, a thrust bearing 27 is interposed
between the rotary support 19 and the front housing 12 for
receiving reaction force of refrigerant gas being discharged from
the cylinder bores 111 through the pistons 23, the shoes 24, the
swash plate 20, the connecting elements 21 and the guide pins
22.
[0029] A projecting portion 28 is formed integrally with the
cylinder block 11 on the top peripheral surface thereof. A muffler
forming portion 29 is connected to the top end of the projecting
portion 28 through a gasket 30. The projecting portion 28 has
formed therein an oil separation chamber 281 which is in
communication with the discharge chamber 132 through a discharge
passage 31. The muffler forming portion 29 is formed integrally
with a cylinder portion 32 for whirling the refrigerant gas,
projecting into the oil separation chamber 281 from the muffler
forming portion 29. The muffler forming portion 29 has formed
therein a muffler chamber 291 which is in communication with the
passage 321 of the cylinder portion 32.
[0030] The suction chamber 131 and the muffler chamber 291 are
connected by an external refrigerant circuit 33 having therein a
condenser 36 for allowing the refrigerant gas from the compressor
10 to be condensed by transferring its heat to cooler surrounding
air, an expansion valve 35 and an evaporator 34 for allowing the
refrigerant liquid to vaporize by absorbing ambient heat. The
expansion valve 35 is a thermal expansion valve for automatically
controlling the flow rate of the refrigerant in accordance with
temperature change of the gas at the exit of the evaporator 34.
[0031] The discharge chamber 132 and the pressure control chamber
121 are connected by a supply passage 37. The pressure control
chamber 121 and the suction chamber 131 are connected by a bleed
passage 38. The refrigerant in the pressure control chamber 121
flows into the suction chamber 131 through the bleed passage
38.
[0032] An electromagnetic displacement control valve 39 is disposed
in the supply passage 37. The supply of the refrigerant from the
discharge chamber 132 to the pressure control chamber 121 through
the supply passage 37 is increased or decreased in accordance with
the opening of the displacement control valve 39. Since the
refrigerant in the pressure control chamber 121 flows into the
suction chamber 131 through the bleed passage 38, the pressure in
the pressure control chamber 121 is changed depending on the supply
of the refrigerant from the discharge chamber 132 to the pressure
control chamber 121 through the supply passage 37. As the supply of
the refrigerant increases, the pressure in the pressure control
chamber 121 rises, while as the supply of the refrigerant
decreases, the pressure in the pressure control chamber 121 falls.
Therefore, the inclination of the swash plate 20 is increased or
decreased thereby to control the displacement of the compressor 10.
The pressure control chamber 121 is in a pressure region other than
the discharge-pressure region.
[0033] As shown in FIG. 4, an annular groove 40 is formed in the
front face 143 of the valve plate 14 adjacent to the suction valve
plate 15 so as to entirely surround the axis 181 of the rotary
shaft 18. The annular groove 40 that serves as an annular passage
is formed so as to encompass all the cylinder bores 111. As shown
in FIG. 1 B, the annular groove 40 is in communication with the oil
separation chamber 281 through a return passage 41 formed in the
suction valve plate 15 and the cylinder block 11. The annular
groove 40 is covered by part of the suction valve plate 15 other
than the suction valves 151.
[0034] As shown in FIG. 5, an oil supply groove 42 is radially
formed in the front face 143 which is covered by the flexible
suction valve 151. The oil supply groove 42 is located adjacent to
the proximal side of the suction valve 151 and connected to the
annular groove 40. The oil supply groove 42 is provided for each
suction valve 151.
[0035] The refrigerant discharged into the discharge chamber 132
that is a part of the discharge-pressure region is flowed into the
external refrigerant circuit 33 through the discharge passage 31,
the oil separation chamber 281, the passage 321 of the cylinder
portion 32 and the muffler chamber 291 each of which is also a part
of the discharge-pressure region of the compressor 10. The
refrigerant flowed into the external refrigerant circuit 33 returns
to the suction chamber 131 that forms a part of the
suction-pressure region.
[0036] The refrigeration circuit formed by the variable
displacement compressor 10 and the external refrigerant circuit 33
contains therein lubricating oil which flows with the refrigerant
in the circuit. The refrigerant flowed from the discharge passage
31 into the oil separation chamber 281 is transferred toward the
bottom of the oil separation chamber 281 while swirling around the
outer peripheral surface of the cylinder portion 32, so that the
oil in mist form flowing with the refrigerant is separated from the
refrigerant. The oil separated from the refrigerant is transferred
to the oil supply groove 42 through the return passage 41 and the
annular groove 40. The return passage 41, the annular groove 40 and
the oil supply groove 42 form an oil supply passage 43 (shown in
FIG. 3), which is opened or closed in accordance with the motion of
the suction valve 151. The oil supply groove 42 forms the outlet of
the oil supply passage 43.
[0037] In operation of the compressor 10 during the compression or
discharge stroke of the piston 23 (rightward movement of the piston
23 as seen in FIG. 1A), the suction valve 151 is in tight contact
with the front face 143 of the valve plate 14 thereby to close the
suction port 141. In this state, the oil supply groove 42 that is a
part of the oil supply passage 43 is closed by the suction valve
151, so that oil does not leak from the oil supply groove 42 into
the cylinder bore 111. During the suction stroke of the piston 23
(leftward movement of the piston 23 in FIG. 1A), the suction valve
151 is moved away from the front face 143 of the valve plate 14
thereby to open the suction port 141, which enables the oil supply
groove 42 to communicate with the cylinder bore 111. Therefore, the
oil in the oil supply groove 42 is fed into the cylinder bore
111.
[0038] According to the first embodiment, the following
advantageous effects are obtained.
[0039] (1) The flexible plate-like suction valve 151 is caused to
open and close the suction port 141 and the oil supply passage 43
each time the piston 23 makes a reciprocating motion. During the
suction stroke of the piston 23, the oil supply passage 43 is
opened and, therefore, the oil in the oil supply groove 42 which is
separated from the refrigerant is supplied into the cylinder bore
111. Since the suction valve 151 is brought into tight contact with
the front face 143 of the valve plate 14 by the discharge pressure,
oil in the oil supply passage 43 which is then closed by the
suction valve 151 does not leak into the cylinder bore 111 through
the gap between the suction valve 151 and the valve plate 14.
Therefore, the oil reserved in the oil separation chamber 281 will
not be drained and the refrigerant in the discharge-pressure region
will not leak into the cylinder bore 111 through the oil supply
passage 43.
[0040] (2) The oil supplied into the cylinder bore 111 lubricates
the sliding portion between the inner peripheral surface of the
cylinder bore 111 and the outer peripheral surface of the piston
23. Since the oil separated in the oil separation chamber 281 is
directly supplied into the cylinder bore 111 through the oil supply
passage 43, a relatively large amount of oil will be supplied into
the cylinder bore 111. Therefore, the sliding portion between the
inner peripheral surface of the cylinder bore 111 and the outer
peripheral surface of the piston 23 is sufficiently lubricated
thereby to improve abrasion resistance of the inner peripheral
surface of the cylinder bore 111 and the outer peripheral surface
of the piston 23.
[0041] (3) The oil is supplied from the oil supply passage 43 into
the cylinder bore 111 only when the suction port 141 is opened by
the suction valve 151. Therefore, compared to the case where the
oil supply passage between the oil separation chamber 281 and the
cylinder bore 111 is constantly opened, the cross sectional area of
the oil supply passage 43 is enlarged. This is advantageous in that
clogging of the oil supply passage 43 with foreign substance is
prevented successfully.
[0042] (4) The oil supply groove 42 opened or closed by the suction
valve 151 for each cylinder bore 111 is in communication with the
oil separation chamber 281 through the annular groove 40. The
annular groove 40 enables the oil to be supplied from the oil
separation chamber 281 to all the cylinder bores 111.
[0043] (5) A large amount of oil should be supplied from the oil
supply passage 43 to the cylinder bore 111 in case of a compressor
having a large displacement or a piston with a large stroke
distance, while a small amount of oil may be supplied in case of a
compressor with a smaller displacement or a piston with a shorter
stroke distance.
[0044] The large displacement increases the moving distance or the
opening of the suction valve 151 from the front face 143 of the
valve plate 14, whereas the small displacement decreases the
distance or the opening. That is, in the case of the large
displacement which needs a large amount of oil supplied into the
cylinder bore 111, the amount of oil supplied from the oil supply
passage 43 to the cylinder bore 111 is large, while in the case of
the small displacement which needs only a small amount of oil to be
supplied into the cylinder bore 111, the amount of oil supplied
from the oil supply passage 43 to the cylinder bore 111 is
small.
[0045] The above-described structure wherein the oil supply passage
43 is opened and closed by the suction valve 151 enables
appropriate oil supply as desired by a specific displacement of the
variable displacement compressor 10.
[0046] (6) By changing design value of the maximal moving distance
of the suction valve 151 when it is moved away from the front face
143 of the valve plate 14, the oil supply from the oil supply
passage 43 to the cylinder bore 111 may be set appropriately.
(7) By changing design value of the length or width of the oil
supply groove 42, the oil supply from the oil supply passage 43 to
the cylinder bore 111 may be set appropriately.
[0047] The following will describe a second embodiment of an oil
recovery structure according to the present invention as applied to
a variable displacement compressor with reference to FIG. 6. The
same reference numerals will be used for the same components or
elements of the second embodiment as those of the first
embodiment.
[0048] In the second embodiment, a pair of oil supply grooves 42,
42A is formed in the front face 143 of the valve plate 14 on each
side of the suction valve 151 adjacent to the proximal side thereof
and in facing relation to the suction valve 151. The oil supply
grooves 42, 42A are connected to the annular groove 40. By so
arranging the paired oil supply grooves 42, 42A, the pressure for
supplying the oil from the oil supply grooves 42, 42A to the
cylinder bore 111 is substantially the same on both sides of the
suction valve 151, so that the suction valve 151 is smoothly opened
and closed without being twisted. Therefore, the suction valve 151
is highly in tight contact with the front face 143 of the valve
plate 14, with the result that leakage of high-pressure gas in the
cylinder bore 111 through the suction port 141 into the suction
chamber 131 is prevented (refer to FIG. 1A).
[0049] The following will describe a third embodiment of an oil
recovery structure according to the present invention as applied to
a fixed displacement compressor with reference to FIGS. 7 through
9B. The same reference numerals will be used for the same
components or elements of the third embodiment as those of the
first embodiment. As shown in FIG. 7, the rear housing 13 has the
discharge chamber 132 formed therein. The front housing 12 and the
cylinder block 11 rotatably support a rotary shaft 44 through a
bearing 45 and a rotary valve portion 46, respectively. A cam 47 of
a swash-plate shape is disposed in a cam chamber 48 and fixed to
the rotary shaft 44.
[0050] A thrust bearing 49 is interposed between the front housing
12 and the cam 47. A plate 50 and a compression spring 51 are
provided between the end of the rotary valve portion 46 and the
valve plate 14. The resilient force of the compression spring 51
prevents free axial movement in the direction of an axis 441 of the
rotary shaft 44.
[0051] The rotary motion of the cam 47 which is rotatable with the
rotary shaft 44 is transmitted to the piston 23 through its shoes
24 which are in slide contact with the cam 47, thereby causing the
piston 23 to reciprocate in its cylinder bore 111.
[0052] The rotary shaft 44 has an axial passage 52 formed therein.
The rotary shaft 44 also has an inlet 53 formed on the peripheral
surface thereof, through which the axial passage 52 is in
communication with the cam chamber 48. The refrigerant in the cam
chamber 48 is flowed into the axial passage 52 through the inlet
53.
[0053] The rotary valve portion 46 has formed therein a
communication hole 461 which is in communication with the axial
passage 52. The cylinder block 11 has formed therein a suction port
54 which is in communication with the cylinder bore 111. The
communication hole 461 is brought into communication intermittently
with the suction port 54 in accordance with the rotation of the
rotary shaft 44.
[0054] During the suction stroke of the piston 23 (leftward
movement of the piston 23 as seen in FIG. 7), the suction port 54
in communication with the cylinder bore 111 for the piston 23 is in
communication with the communication hole 461. During the above
suction stroke, the refrigerant in the axial passage 52 of the
rotary valve portion 46 is drawn into the cylinder bore 111 through
the communication hole 461 and the suction port 54.
[0055] On the other hand, during the compression or discharge
stroke of the piston 23 (rightward movement of the piston 23 as
seen in FIG. 7), the communication between the suction port 54 and
the communication hole 461 is shut off. During the above
compression or discharge stroke, the refrigerant in the cylinder
bore 111 forces the discharge valve 161 away from the discharge
port 142 and is discharged into the discharge chamber 132. The
refrigerant discharged into the discharge chamber 132 flows into
the external refrigerant circuit 33 through the discharge passage
31, the oil separation chamber 281 and the muffler chamber 291. The
refrigerant flowing through the external refrigerant circuit 33
returns to the cam chamber 48 which forms a part of the
suction-pressure region of the compressor.
[0056] As shown in FIG. 8, the cylinder block 11 has formed in the
rear end face thereof an annular groove 55, a communication groove
56 and a plurality of oil supply grooves 57. The annular groove 55
is formed so as to encompass all the cylinder bores 111. Each oil
supply groove 57 is in communication with the return passage 41
through the annular groove 55 and the communication groove 56 and
also in communication with the respective cylinder bore 111.
[0057] As shown in FIGS. 9A and 9B, a rod-shaped shutter 58 extends
through the valve plate 14 for opening and closing the
communication groove 56. The shutter 58 is attached to the
discharge valve 161. The shutter 58 is operable to open and close
the communication groove 56 in conjunction with the operation of
the discharge valve 161 to open and close the discharge port 142.
FIG. 9A shows the closed state of the communication groove 56. In
this state, oil is not transferred from the return passage 41 to
the annular groove 55. FIG. 9B shows the opened state of the
communication groove 56, wherein the oil in the return passage 41
is transferred to the annular groove 55. The return passage 41, the
communication groove 56, the annular groove 55 and the oil supply
grooves 57 cooperate to form the oil supply passage 59, which is
opened and closed in accordance with the operation of the discharge
valve 161. The oil supply grooves 57 forms the outlet of the oil
supply passage 59.
[0058] The oil recovery structure of this third embodiment is so
arranged that a slight clearance is formed between the outer
peripheral surface of the shutter 58 and the cylinder block 11 even
when the shutter 58 closes the communication groove 56. Since the
cross sectional area of the communication groove 56 is relatively
small, however, the cross sectional area of the clearance is
extremely small. Therefore, leakage of the oil through the oil
supply passage 59 hardly occurs when the oil supply passage 59 is
closed.
[0059] The oil is supplied from the oil supply passage 59 to the
cylinder bore 111 only when the discharge port 142 is opened by the
discharge valve 161. Therefore, compared to the case where an oil
supply passage between the oil separation chamber 281 and the
cylinder bore 111 is constantly opened, the cross sectional area of
the oil supply passage 59 of the third embodiment is enlarged. This
is advantageous in that clogging of the oil supply passage 59 with
foreign substance is prevented successfully.
[0060] According to the third embodiment, the effects similar to
the effects as described under (2) and (4) of the first embodiment
are obtained.
[0061] The present invention may be practiced in the following
modifications of the above embodiments.
[0062] The shape of the oil supply passage formed in the valve
plate 14 may be a hole that extends through the valve plate 14, so
that the outlet of the oil supply passage (oil supply port) in the
valve plate 14 is opened to the cylinder bore 111.
[0063] The first through third embodiments may be modified such
that the oil in the oil supply passage is supplied to only one of
the plural cylinder bores 111.
[0064] The first embodiment may be modified such that the oil in
the oil supply passage is supplied to the pressure control chamber
121 (pressure region other than the discharge-pressure region).
[0065] The first embodiment may be modified such that the oil in
the oil supply passage is supplied to the suction chamber 131.
[0066] The third embodiment may be modified such that the oil in
the oil supply passage is supplied to the cam chamber 48.
[0067] The first embodiment may be modified such that the annular
groove 40 is formed in the cylinder block 11 or alternatively in a
space surrounded by the cylinder block 11 and the valve plate
14.
[0068] The present invention is also applicable to a piston type
fixed displacement compressor having a flexible plate-like suction
valve.
[0069] The first through third embodiments may be modified such
that the oil is separated from the refrigerant in the external
refrigerant circuit 33 and the separated oil is supplied into the
compressor through the oil supply passage.
[0070] The first through third embodiments may be modified such
that the oil is separated from the refrigerant in the pressure
region in the pressure control chamber 121 or in the
suction-pressure region of the compressor and the separated oil is
supplied through the oil supply passage.
[0071] The present invention is also applicable to a piston
compressor having a cam member with a shape other than that of a
swash plate.
[0072] 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.
* * * * *