U.S. patent application number 14/365583 was filed with the patent office on 2014-12-18 for compressor.
This patent application is currently assigned to Valeo Japan Co., Ltd. The applicant listed for this patent is Valeo Japan Co., Ltd.. Invention is credited to Minoru Kanaizuka, Keizou Nako, Mitsuya Ono, Osamu Shirakura.
Application Number | 20140369871 14/365583 |
Document ID | / |
Family ID | 48612204 |
Filed Date | 2014-12-18 |
United States Patent
Application |
20140369871 |
Kind Code |
A1 |
Ono; Mitsuya ; et
al. |
December 18, 2014 |
Compressor
Abstract
A compressor includes a housing; a suction region and a
discharge region which are formed in the housing in a partitioned
manner. The compressor also includes a shaft which is pivotally
supported in the inside of the housing. The compressor further
includes a compression mechanism which sucks a refrigerant from the
suction region and discharges the refrigerant to the discharge
region due to a rotational motion of the shaft. The compressor
further includes a bypass passage which makes the suction region
and the discharge region communicate with each other, a valve
element 41 which is capable of closing the bypass passage 40 from a
discharge region side, and a spring which biases the valve element
toward the discharge region side.
Inventors: |
Ono; Mitsuya; (Kumagaya-shi,
JP) ; Kanaizuka; Minoru; (Kumagaya-shi, JP) ;
Nako; Keizou; (Kumagaya-shi, JP) ; Shirakura;
Osamu; (Kumagaya-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Valeo Japan Co., Ltd. |
Kumagaya-shi |
|
JP |
|
|
Assignee: |
Valeo Japan Co., Ltd
Kumagaya-shi
JP
|
Family ID: |
48612204 |
Appl. No.: |
14/365583 |
Filed: |
December 14, 2012 |
PCT Filed: |
December 14, 2012 |
PCT NO: |
PCT/JP2012/007999 |
371 Date: |
June 13, 2014 |
Current U.S.
Class: |
417/440 |
Current CPC
Class: |
F04B 27/1009 20130101;
F04B 39/04 20130101; F04B 27/08 20130101; F04B 49/24 20130101; F04B
27/1036 20130101; F04B 27/12 20130101 |
Class at
Publication: |
417/440 |
International
Class: |
F04B 49/24 20060101
F04B049/24; F04B 39/04 20060101 F04B039/04; F04B 27/12 20060101
F04B027/12 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 16, 2011 |
JP |
JP 2011-275530 |
Claims
1. A compressor comprising: a housing; a suction region and a
discharge region which are formed in the housing in a partitioned
manner; a shaft which is pivotally supported in an inside of the
housing; and a compression mechanism which sucks a refrigerant from
the suction region and discharges the refrigerant to the discharge
region due to a rotational motion of the shaft; a bypass passage
which makes the suction region and the discharge region communicate
with each other; a valve element which is capable of closing the
bypass passage from a discharge region side; and a spring which
biases the valve element toward the discharge region side.
2. The compressor according to claim 1, wherein a valve port formed
with a diameter smaller than an outer diameter of the valve
element, and a valve accommodating hole formed on a discharge
region side with respect to the valve port with a diameter larger
than the outer diameter of the valve element are formed in the
bypass passage, and the valve element is accommodated in the valve
accommodating hole in an axially movable manner.
3. The compressor according to claim 2, wherein an area of a
passage formed between an outer peripheral surface of the valve
element and an inner peripheral surface of the valve accommodating
hole is set smaller than an area of the valve port.
4. The compressor according to claim 1, wherein the housing is
constituted of shell members formed by dividing the housing in two
in the axial direction of the shaft, the discharge region and the
suction region are defined in the respective shell members, a
discharge port which is communicated with the discharge region and
a suction port which is communicated with the suction region are
formed in either one of the shell members, and the bypass passage
is formed in the one shell member in which the discharge port and
the suction port are formed.
5. The compressor according to claim 4, wherein the valve element
is formed of a steel ball, and a valve seat face on which the valve
element is seated is formed on a portion shifting to the valve
accommodating hole from the valve port.
6. The compressor according to claim 2, wherein the housing is
constituted of shell members formed by dividing the housing in two
in the axial direction of the shaft, the discharge region and the
suction region are defined in the respective shell members, a
discharge port which is communicated with the discharge region and
a suction port which is communicated with the suction region are
formed in either one of the shell members, and the bypass passage
is formed in the one shell member in which the discharge port and
the suction port are formed.
7. The compressor according to claim 3, wherein the housing is
constituted of shell members formed by dividing the housing in two
in the axial direction of the shaft, the discharge region and the
suction region are defined in the respective shell members, a
discharge port which is communicated with the discharge region and
a suction port which is communicated with the suction region are
formed in either one of the shell members, and the bypass passage
is formed in the one shell member in which the discharge port and
the suction port are formed.
8. The compressor according to claim 1, wherein the valve element
is formed of a steel ball, and a valve seat face on which the valve
element is seated is formed on a portion shifting to the valve
accommodating hole from the valve port.
9. The compressor according to claim 2, wherein the valve element
is formed of a steel ball, and a valve seat face on which the valve
element is seated is formed on a portion shifting to the valve
accommodating hole from the valve port.
10. The compressor according to claim 3, wherein the valve element
is formed of a steel ball, and a valve seat face on which the valve
element is seated is formed on a portion shifting to the valve
accommodating hole from the valve port.
Description
TECHNICAL FIELD
[0001] The present invention relates to a compressor of a
refrigerating cycle used in a vehicle-use air conditioner or the
like, and more particularly to a compressor having a function of
suppressing the flowing out of lubrication oil in the compressor to
the outside of the compressor due to the movement of a refrigerant
in the refrigerating cycle caused by a change in temperature when
the compressor is stopped.
BACKGROUND ART
[0002] In a refrigerating cycle used in an automobile-use air
conditioner, using a partition wall (fire wall) which partitions an
engine room side and a cabin side from each other as a boundary, an
evaporator is arranged in the cabin side, and a condenser, a
compressor and the like are arranged in the engine room side. In
such a refrigerating cycle, when a vehicle is warmed by sunbeams
during daytime in a state where the operation of the compressor is
stopped, as shown in FIG. 6, a temperature of an evaporator A
arranged in the cabin side which is liable to be warmed by sunbeams
is also elevated, while temperatures of a condenser B and a
compressor C arranged in the inside of the engine room are not
elevated to an extent that the temperature of the evaporator A is
elevated. Further, the compressor C having a large thermal capacity
is hardly warmed and hence, the compressor C is a place which
exhibits the lowest temperature in the refrigerating cycle so that
a refrigerant is condensed in the compressor. Accordingly, in the
compressor, due to oil (lubrication oil) and liquefied refrigerant,
a liquid whose amount exceeds an oil storage capacity stays.
[0003] On the other hand, when evening arrives and the vehicle is
no more heated by sunbeams, a temperature of the condenser having a
small thermal capacity is gradually lowered, and the following
relationship is established among the respective temperatures of
the evaporator, the compressor, and the condenser.
evaporator temperature>compressor temperature>condenser
temperature
[0004] Due to such temperature difference, a pressure in the
condenser becomes the lowest in the refrigerating cycle thus giving
rise a phenomenon where a refrigerant which remains in the
compressor and into which oil is dissolved is pushed out to a
condenser side due to a pressure from the evaporator.
[0005] When such a phenomenon caused by a change in temperature
happens repeatedly, oil held in the compressor is gradually
conveyed to the outside of the compressor and, eventually, oil
remaining in the compressor is depleted. Accordingly, when an air
conditioner is operated again after a long period where the air
conditioner is not used at all, there is fear that a seizure of the
compressor arises due to lubrication failure.
[0006] To overcome such a drawback, conventionally, as described in
the following PTL 1, there has been proposed the constitution where
a low-pressure pipe which is connected to a suction port of a
compressor in a refrigerating cycle and a high-pressure pipe which
is connected to a discharge port of the compressor are connected to
each other by a bypass pipe passage, a check valve which allows the
flow of a refrigerant to the bypass pipe passage when a refrigerant
pressure on a low-pressure pipe side (evaporator side) becomes
higher than a refrigerant pressure on a high-pressure pipe side
(condenser side) is mounted in the bypass pipe passage. Due to such
a constitution, in a state where an operation of the compressor is
stopped, when the refrigerant pressure on the low-pressure pipe
side becomes higher than the refrigerant pressure on the
high-pressure pipe side, the check valve is opened due to the
pressure difference so that the refrigerant on the low-pressure
pipe side is made to flow to the high-pressure pipe side through
the bypass pipe passage thus almost preventing the refrigerant from
flowing into the inside of the compressor whereby the flowing out
of oil from the compressor is prevented.
CITATION LIST
Patent Literature
[0007] PTL 1: JP-A-7-218007
SUMMARY OF INVENTION
Technical Problem
[0008] However, the check valve disclosed in the above-mentioned
patent literature is configured such that a compression coil spring
is arranged in a high-pressure pipe side of a valve element which
constitutes a part of the check valve, and the valve element is
biased in the closing direction by a biasing force of the
compression coil spring. Due to such a constitution, unless a
refrigerant pressure on a low-pressure pipe side (evaporator side)
is increased by an amount corresponding to a spring force of the
compression coil spring with respect to a refrigerant pressure on a
high-pressure pipe side (condenser side), the bypass passage is not
released. Accordingly, when a refrigerant pressure on the
low-pressure pipe side (evaporator side) does not reach a pressure
at which the valve element can be opened by pushing against the
spring force of the compression coil spring although the
refrigerant pressure on the low-pressure pipe side (evaporator
side) is higher than the refrigerant pressure on the high-pressure
pipe side (condenser side), a liquid refrigerant in the compressor
is pushed out to the high-pressure pipe side (condenser side)
together with oil due to the difference in pressure and hence,
there still exists a possibility that oil in the compressor is
depleted.
[0009] The present invention has been made in view of such
circumstances, and it is a primary object of the present invention
to provide a compressor capable of effectively suppressing the
flowing out of lubrication oil in a compressor to the outside of
the compressor due to the movement of a refrigerant in a
refrigerating cycle caused by a change in temperature in a state
where an operation of the compressor is stopped.
Solution to Problem
[0010] To achieve the above-mentioned object, a compressor
according to the present invention includes: a housing; a suction
region and a discharge region which are formed in the housing in a
partitioned manner; a shaft which is pivotally supported in the
inside of the housing; and a compression mechanism which sucks a
refrigerant from the suction region and discharges the refrigerant
to the discharge region due to a rotational motion of the shaft,
wherein the compressor further includes: a bypass passage which
makes the suction region and the discharge region communicate with
each other; a valve element which is capable of closing the bypass
passage from a discharge region side; and a spring which biases the
valve element toward the discharge region side (toward the valve
opening direction).
[0011] Due to the above-mentioned constitution, in a state where
the operation of the compressor is stopped, when a refrigerant
pressure in the discharge region (high-pressure pipe side) which is
defined in the housing and a refrigerant pressure in the suction
region (low-pressure pipe side) which is defined in the housing are
balanced with each other, the bypass passage is always opened.
Accordingly, even when the refrigerant pressure on the suction
region side (low-pressure pipe side) becomes slightly higher than
the refrigerant pressure on the discharge region side
(high-pressure pipe side) due to a change in temperature, it is
possible to promptly release the refrigerant pressure on the
suction region side (low-pressure pipe side) to the discharge
region side (high-pressure pipe side) through the bypass passage
and hence, there is no possibility that oil remaining in the
compressor is taken out to the high-pressure pipe side together
with a liquid refrigerant.
[0012] It is preferable that, a valve port formed with a diameter
smaller than an outer diameter of the valve element, and a valve
accommodating hole formed on a discharge region side with respect
to the valve port with a diameter larger than the outer diameter of
the valve element are formed in the bypass passage directly or by
way of a holder, and the valve element is accommodated in the valve
accommodating hole in an axially movable manner.
[0013] Due to such a constriction, when the operation of the
compressor is started, the valve element accommodated in the valve
accommodating hole moves in the valve accommodating hole promptly
so that the bypass passage is closed by the valve element. This
state is maintained until the compressor is stopped again so that
the pressure difference between the discharge region and the
suction region is decreased to an extent that the valve element is
movable toward a discharge region side (toward the valve opening
direction) due to a spring force of the spring.
[0014] Assuming that, as shown in FIG. 7, a valve element A were
positioned in an open space of the discharge region, when the
operation of the compressor is started, a refrigerant gas which
tends to flow into the suction region from the discharge region
through a bypass passage B would pass through a gap between the
valve element A and a peripheral edge of an opening end of the
bypass passage B instead of passing along side of the valve element
A, and directly flows into the suction region. Accordingly, the
valve element A does not close the bypass passage B thus giving
rise to a drawback that a refrigerant gas is blown off into the
suction region from the discharge region. However, by adopting the
above-mentioned constitution, a refrigerant which tends to flow to
a suction region side from a discharge region side passes along a
side surface of the valve element held in the valve accommodating
hole and, thereafter, flows out to the suction region through the
valve port. Accordingly, the flow of the refrigerant works to push
the valve element toward a valve port side against a spring force,
and this force allows the valve element to promptly close the valve
port. Once the valve element closes the valve port, a discharge
pressure and a suction pressure act on a front side and a rear side
of the valve element respectively, and a closed state is maintained
against a spring force of the spring due to such pressure
difference.
[0015] To acquire such an action more effectively, it is preferable
that an area of a passage formed between an outer peripheral
surface of the valve element and an inner peripheral surface of the
valve accommodating hole is set smaller than an area of the valve
port. Due to such a constitution, pressure drop in the bypass
passage from the discharge region to the suction region is
preferentially imparted to before and after a refrigerant passes
along the valve element rather than to before and after a
refrigerant passes through the valve port and hence, the pressure
difference can be surely generated on an upstream side and a
downstream side of the valve element whereby the valve element can
be moved promptly.
[0016] Further, in the compressor where the housing is constituted
of shell members formed by dividing the housing in two in the axial
direction of the shaft, the discharge region and the suction region
are defined in the respective shell members, and a discharge port
which is communicated with the discharge region and a suction port
which is communicated with the suction region are formed in either
one of the shell members, it is desirable that the bypass passage
is formed in the above-mentioned one shell member in which the
discharge port and the suction port are formed so as to make the
above-mentioned refrigerant which moves due to a change in
temperature flow toward a high-pressure pipe side without passing
the inside of the compressor as much as possible whereby the
flowing out of oil in the compressor is prevented.
[0017] The above-mentioned constitution may be realized such that
the valve element is formed of a steel ball, the spring
accommodated in the valve port is formed of a compression coil
spring, and a valve seat face on which the valve element is seated
is formed on a portion shifting to the valve accommodating hole
from the valve port.
Advantageous Effects of Invention
[0018] As has been explained heretofore, according to the present
invention, the suction region and the discharge region defined in
the housing of the compressor are communicated with each other by
forming the bypass passage, and the valve element which is capable
of closing the bypass passage from a discharge region side and the
spring which biases the valve element toward the discharge region
side (toward the valve opening direction) are provided to the
bypass passage. Due to such a constitution, even when a refrigerant
pressure in the suction region, that is, on a low-pressure pipe
side (evaporator side) is slightly increased also with respect to a
refrigerant pressure in the discharge region, that is, on a
high-pressure pipe side (condenser side), the refrigerant pressure
on the suction region side (low-pressure pipe side) can be promptly
released to the discharge region side (high-pressure pipe side)
through the bypass passage whereby there is no fear that oil
remaining in the compressor is taken out to the outside of the
compressor together with a liquid refrigerant.
[0019] The valve port formed with a diameter smaller than an outer
diameter of the valve element, and a valve accommodating hole
formed on a discharge region side with respect to the valve port
with a diameter larger than the outer diameter of the valve element
are formed in the bypass passage directly or by way of a holder,
the spring is held on the valve port, and the valve element is
accommodated in the valve accommodating hole in an axially movable
manner. Due to such a constitution, the valve element can be moved
against a spring force of the spring by a refrigerant which tends
to flow in the bypass passage along a side of the valve element
immediately after the operation of the compressor is started and
hence, the valve port can be promptly closed and the closed state
can be maintained in a stable manner.
[0020] In this case, by setting the area of the passage formed
between the outer peripheral surface of the valve element and the
inner peripheral surface of the valve accommodating hole smaller
than the area of the valve port, it is possible to make the valve
element react more sensitively by a refrigerant which tends to flow
the bypass passage immediately after the operation of the
compressor is started and hence, the valve element can promptly and
surely close the valve port.
[0021] Further, in the compressor where the housing is constituted
of the shell members formed by dividing the housing in two in the
axial direction of the shaft, the discharge region and the suction
region are defined in the respective shell members, and the
discharge port which is communicated with the discharge region and
the suction port which is communicated with the suction region are
formed in either one of the shell members, by forming the bypass
passage in one shell member in which the discharge port and the
suction port are formed, even when the bypass passage is formed in
the compressor, a refrigerant passes only in the vicinity of the
port without passing the inside of the compressor as much as
possible and hence, it is possible to surely prevent oil from being
taken out from the compressor.
BRIEF DESCRIPTION OF DRAWINGS
[0022] FIG. 1(a) is a cross-sectional view showing an example of a
compressor according to the present invention in which a bypass
passage is formed, and FIG. 1(b) is a view of a rear-side shell
member as viewed from an inner side in the axial direction.
[0023] FIG. 2(a) and FIG. 2(b) are conceptual views for explaining
the flow of a refrigerant in the compressor according to the
present invention, wherein FIG. 2(a) is a side cross-sectional view
of the compressor, and FIG. 2(b) is a cross-sectional view taken
along a line B-B in FIG. 2(a).
[0024] FIG. 3 is a cross-sectional view of the rear-side shell
member, and is also a view taken along a line A-A in FIG. 1(b) (a
view showing the compressor in cross section such that the bypass
passage can be observed).
[0025] FIG. 4(a) and FIG. 4(b) are enlarged cross-sectional views
showing a portion of the bypass passage where a valve element and a
spring are provided, wherein FIG. 4(a) is the view showing a state
where the valve element is away from a valve seat face, and FIG.
4(b) is a view showing a state where the valve element is seated on
the valve seat face.
[0026] FIG. 5 is an enlarged cross-sectional view showing a portion
of the bypass passage where the valve element and the spring are
provided, and is also a view for explaining the flow of a
refrigerant which flows through the bypass passage and the behavior
of the valve element.
[0027] FIG. 6 is a view showing a graph which indicates changes in
temperature in an evaporator, a condenser, and the compressor in a
refrigerating cycle mounted on a vehicle, and a schematic view for
explaining the flow of a refrigerant and the flow of oil in a state
where the compressor is stopped.
[0028] FIG. 7 is a view for explaining the flow of the refrigerant
and the behavior of the valve element when the valve element is
positioned in an open space of a discharge region.
DESCRIPTION OF EMBODIMENTS
[0029] Hereinafter, an embodiment of the present invention is
explained by reference to attached drawings.
[0030] In FIG. 1 and FIG. 2, a compressor 1 is a reciprocating-type
compressor employed in a refrigerating cycle where a refrigerant is
used as a working fluid. The compressor 1 includes: a front-side
cylinder block 2; a rear-side cylinder block 4 which is assembled
to the front-side cylinder block 2; a front-side shell member 6
which is assembled to a front side (a left side in the drawing) of
the front-side cylinder block 2 with a valve plate 5 interposed
therebetween; and a rear-side shell member 8 which is assembled to
a rear side (a right side in the drawing) of the rear-side cylinder
block 4 with a valve plate 7 interposed therebetween. The
front-side shell member 6 and the rear-side shell member 8
respectively have opening end sides thereof extended so as to cover
the cylinder blocks 2, 4 which are arranged close to the front-side
shell member 6 and the rear-side shell member 8 respectively and
are engaged with each other in the axial direction by fitting
engagement. The front-side shell member 6, the valve plate 5, the
front-side cylinder block 2, the rear-side cylinder block 4, the
valve plate 7 and the rear-side shell member 8 are fastened to each
other in the axial direction using fastening bolts 9. The
front-side shell member 6 and the rear-side shell member 8
constitute a housing of the compressor which is divided in two in
the axial direction.
[0031] In the inside of the front-side cylinder block 2 and the
rear-side cylinder block 4, a swash plate accommodating chamber 10
is formed in a defined manner by assembling the front-side cylinder
block 2 and the rear-side cylinder block 4 to each other. In the
swash plate accommodating chamber 10, a shaft 12 is rotatably
supported by shaft support holes 11 formed in the front-side
cylinder block 2 and the rear-side cylinder block 4 respectively by
way of radial bearings 19. One end of the shaft 12 projects from
the front-side shell member 6, and a relay member 14 is fixed to
the portion of the shaft 12 projecting from the front-side shell
member 6 in a state where the relay member 14 is mounted in the
axial direction using a bolt 13. A boss portion 6a which extends
toward a front side so as to cover the shaft is integrally formed
with the front-side shell member 6, and a pulley 16 which is
connected to a drive source not shown in the drawing by way of a
belt is rotatably fitted on the boss portion 6a by way of a bearing
15. The pulley 16 transmits rotational power to the shaft 12 by way
of the relay member 14.
[0032] A plurality of cylinder bores 17 which are arranged parallel
to the shaft support hole 11 and are arranged equidistantly on the
circumference about the shaft 12 are formed in the respective
cylinder blocks 2, 4. In the inside of each cylinder bore 17, a
double-headed piston 18 having head portions on both ends thereof
is inserted and is slidable in a reciprocating manner, and
compression chambers 25 are defined between the double-headed
piston 18 and the valve plates 5, 7 respectively.
[0033] A swash plate 20 which is accommodated in the swash plate
accommodating chamber 10 and is rotated integrally with the shaft
12 is fixed to the shaft 12. The swash plate 20 is rotatably
supported on the front-side cylinder block 2 and the rear-side
cylinder block 4 by way of thrust bearings 21, and a peripheral
edge portion of the swash plate 20 is sandwiched between a pair of
semispherical shoes 22 which is engaged with an engaging recessed
portion 23 formed on a center portion of the double-headed piston
18 such that a front side and a rear side of the peripheral portion
is sandwiched by the semispherical shoes 22. Accordingly, when the
shaft 12 is rotated so that the swash plate 20 is rotated in an
oscillating manner, such an oscillating rotation motion is
converted into a reciprocating motion of the double-headed piston
18 by way of the shoes 22 so that a capacity of the compression
chamber 25 is changed.
[0034] In each of the respective valve plates 5, 7, a suction hole
26 which is opened or closed by a suction valve not shown in the
drawing which is mounted on a cylinder-block-side end face of the
valve plate 5, 7, and a discharge hole 27 which is opened or closed
by a discharge valve not shown in the drawing which is mounted on a
shell-member-side end face of the valve plate 5, 7 are formed
corresponding to each cylinder bore 17. A suction chamber 28 for
accommodating a refrigerant to be supplied to the compression
chamber 25 and a discharge chamber 29 for accommodating a
refrigerant to be discharged from the compression chamber 25 are
defined in the front-side shell member 6 and the rear-side shell
member 8 respectively.
[0035] The suction chambers 28 formed in the respective shell
members 6, 8 are connected with the swash plate accommodating
chamber 10 through low-pressure passages 30, and the swash plate
accommodating chamber 10 is communicated with a suction port 32
which is formed in the rear-side shell member 8 and is connected to
an external cycle through a suction passage 31 connected to the
swash plate accommodating chamber 10.
[0036] The discharge chambers 29 formed in the respective shell
members 6, 8 are communicated with a discharge port 34 formed in
the rear-side shell member 8 through a discharge passage 33, and
the discharge chambers 29 are connected to the external cycle
through the discharge port 34.
[0037] Accordingly, during a suction stroke where a volume of the
compression chamber 25 is increased along with the reciprocating
movement of the double-headed piston 18, a refrigerant which is
introduced into the suction chamber 28 from the suction port 32
through the suction passage 31, the swash plate accommodating
chamber 10, and the low-pressure passage 30 is sucked into the
compression chamber 25 through the suction hole 26. On the other
hand, during a compression stroke where the volume of the
compression chamber 25 is decreased, a refrigerant which is
compressed in the compression chamber 25 is discharged into the
discharge chamber 29 through the discharge hole 27, is introduced
to the discharge port 34 formed in the rear-side shell member 8
from the discharge chamber 29 through the discharge passage 33, and
is pumped out to the external cycle from the discharge port 34.
[0038] As shown also in FIG. 3, in the rear-side shell member 8, a
bypass passage 40 is formed through which an area in the vicinity
of the suction port 32 of the suction passage 31 which forms a
suction region and an area in the vicinity of the discharge port 34
of the discharge passage 33 which forms a discharge region are
communicated with each other. The bypass passage 40 is constituted
such that a passage forming hole 40a is formed in the rear-side
shell member 8 from an inner face of the discharge passage 33, a
passage forming hole 40b is formed in the rear-side shell member 8
from an inner surface of the suction passage 31, and distal end
portions of the respective passage forming holes 40a, 40b are
communicated with each other. A valve element 41 and a spring 42
are accommodated in the passage forming hole 40a which is formed in
the rear-side shell member 8 from the discharge passage 33.
[0039] To be more specific, as shown in FIG. 4, a valve port 43
which is formed with a diameter smaller than an outer diameter of
the valve element 41 and a valve accommodating hole 44 which is
formed on a discharge region side (a discharge passage 33 side)
with respect to the valve port 43 with a diameter larger than the
outer diameter of the valve element 41 are directly formed in the
passage forming hole 40a of the bypass passage 40 formed from the
discharge passage 33 along the axial direction of the passage
forming hole 40a of the bypass passage 40, and a valve seat face 45
on which the valve element 41 is seated is formed on a portion
shifting to the valve port 43 from the valve accommodating hole 44
in a tapered shape such that a diameter of the valve seat face 45
is gradually decreased.
[0040] In this example, the valve element 41 is formed of a steel
ball, and the spring 42 is formed of a compression coil spring. The
spring 42 is accommodated in and held by the valve port 43, the
valve element 41 is accommodated in and held by the valve 2 0
accommodating hole 44, and the valve element 41 is always biased
toward a discharge region side (a discharge passage 33 side) by the
spring 42. A stopper member mounting hole 46 which opens at an
inner peripheral face of the valve accommodating hole 44 and
extends in the direction different from the axial direction of the
valve accommodating hole 44 is formed in the vicinity of an opening
end of the valve accommodating hole 44 which opens at the discharge
passage 33. A stopper member 47 which is press-fitted in the
stopper member mounting hole 46 is fixed in a projecting manner
such that the stopper member 47 traverses the valve accommodating
hole 44. Accordingly, the valve element 41 is held in the inside of
the valve accommodating hole 44 in a state where the valve element
41 is movable along the axial direction while a moving range of the
valve element 41 is restricted by the stopper member 47.
[0041] An area of a passage between an outer peripheral surface of
the valve element 41 and an inner peripheral surface of the valve
accommodating hole 44 (a value obtained by subtracting a
cross-sectional area of the valve element 41 from a cross-sectional
area of the valve accommodating hole 44 on a plane perpendicular to
an axis of the valve accommodating hole 44) is set smaller than a
cross-sectional area of the valve port 43.
[0042] In the above-mentioned constitution, in a state where the
operation of the compressor 1 is stopped, when a refrigerant
pressure in the compressor on a high-pressure pipe side and a
refrigerant pressure in the compressor on a low-pressure pipe side
are approximately balanced with each other, there exists
substantially no pressure difference between front and rear sides
of the valve element 41 in the bypass passage 40 which is formed
between the discharge region and the suction region, and the valve
element 41 is in a state where the valve element 41 is away from
the valve seat face 45 by being pushed toward a discharge region
side by a spring force of the spring 42 (a state shown in FIG.
4(a)).
[0043] In this state, when a temperature of a refrigerating cycle
apparatus is increased due to the influence of sunbeams and,
thereafter, the vehicle is no more heated by sunbeams so that the
relationship of evaporator temperature>compressor
temperature>condenser temperature is established among a
temperature of the evaporator, a temperature of the compressor and
a temperature of the condenser, a refrigerant tends to flow toward
a high-pressure pipe side from a low-pressure pipe side through the
compressor 1 due to a pressure from the evaporator. However, the
valve element 41 of the bypass passage 40 is in a state where the
valve element 41 is away from the valve seat face 45 and hence, an
area of the suction region in the vicinity of the suction port 32
and an area of the discharge region in the vicinity of the
discharge port 34 are communicated with each other through the
bypass passage 40. Accordingly, a refrigerant on the low-pressure
pipe side can be made to flow promptly toward the high-pressure
pipe side through the bypass passage 40 without passing through the
inside of the compressor. Accordingly, there is no possibility that
a refrigerant which flows from the low-pressure pipe side takes out
oil in the compressor to the outside of the compressor thus
preventing oil in the inside of the compressor from being
depleted.
[0044] On the other hand, immediately after the operation of the
compressor is started, a refrigerant which is compressed by the
piston and is discharged into the discharge region is discharged to
the outside of the compressor and some of the refrigerant tends to
flow in the 2 0 suction region through the bypass passage. In this
case, as shown in FIG. 5, the refrigerant which tends to flow in a
suction region side from a discharge region side passes along the
side of the valve element 41 which is accommodated in the valve
accommodating hole 44 and, thereafter, tends to flow out to the
suction region through the valve port 43. However, the area of the
passage between the valve element 41 and the valve accommodating
hole 44 is set smaller than the cross-sectional area of the valve
port 43 and hence, a pressure of the refrigerant is largely dropped
at the place whereby the pressure difference is surely generated
between an upstream side and a downstream side of the valve element
41. Accordingly, the refrigerant pushes the valve element 41 toward
a valve port 43 side against a spring force of the spring 42 so
that the valve element 41 is promptly seated on the valve seat face
45 due to such a force and closes the valve port 43. Once the valve
element 41 closes the valve port 43, a discharge pressure and a
suction pressure act on front and rear sides of the valve element
41 respectively so that a closed state is maintained in a stable
manner against a spring force of the spring 42 due to such pressure
difference.
[0045] This state is maintained until the compressor 1 is stopped
again so that the pressure difference between the discharge region
side and the suction region side is sufficiently decreased and the
valve element 41 starts to move toward the discharge region side
(toward the valve opening direction) due to the spring force of the
spring 42.
[0046] Particularly, in the above-mentioned constitution, the area
of the passage between the outer peripheral surface of the valve
element 41 and the inner peripheral surface of the valve
accommodating hole 44 is set smaller than the area of the valve
port 43 and hence, immediately after the operation of the
compressor 1 is started, the pressure difference is surely
generated between the front and rear sides of the valve element 41
due to the refrigerant which tends to flow in the bypass passage 40
along the side of the valve element 41 and hence, the valve element
can be moved promptly thus surely closing the valve port 43.
[0047] In the above-mentioned constitution, the constitution where
the valve port 43, the valve accommodating hole 44, and the valve
seat face 45 are integrally formed on a middle portion of the
bypass passage 40 by working an inner wall of the passage is taken
as an example. However, it may be possible to adopt the structure
where a cartridge is formed by accommodating the spring 42 and the
valve element 41 in a holder in which the valve port 43, the valve
accommodating hole 44 and the valve seat face 45 are formed, and
the cartridge is mounted in a middle portion of the bypass passage
40.
[0048] Further, in the above-mentioned example, as the compressor,
the reciprocating-type compressor which makes use of a
double-headed piston is exemplified. However, the compressor is not
limited to such a reciprocating-type compressor, and other
piston-type compressors or compressors of other types may adopt the
substantially same constitution.
Reference Signs List
[0049] 1: compressor [0050] 6: front-side shell member [0051] 8:
rear-side shell member [0052] 12: shaft [0053] 31: suction passage
[0054] 32: suction port [0055] 33: discharge passage [0056] 34:
discharge port [0057] 40: bypass passage [0058] 41: valve element
[0059] 42: spring [0060] 43: valve port [0061] 44: valve
accommodating hole [0062] 45: valve seat face
* * * * *