U.S. patent application number 11/983178 was filed with the patent office on 2008-05-15 for structure for sensing refrigerant flow rate in a compressor.
Invention is credited to Yoshinori Inoue, Akinobu Kanai, Hirokazu Mesaki, Atsuhiro Suzuki.
Application Number | 20080110188 11/983178 |
Document ID | / |
Family ID | 39015683 |
Filed Date | 2008-05-15 |
United States Patent
Application |
20080110188 |
Kind Code |
A1 |
Inoue; Yoshinori ; et
al. |
May 15, 2008 |
Structure for sensing refrigerant flow rate in a compressor
Abstract
A compressor connected to an external refrigerant circuit is
disclosed. The compressor is provided with a housing, a passage
forming member coupled to an outer surface of the housing, and a
differential pressure type flow rate detector provided in the
passage forming member. The flow rate detector obtains the pressure
in an upstream passage and the pressure in a downstream passage to
detect a refrigerant flow rate within the refrigerant passage. The
flow rate detector is provided with an accommodation chamber, a
partition body, a compression spring, and a spring seat defining a
maximum stroke amount of the partition body. The spring seat exists
closer to the passage forming member side than a partition surface
comparting the housing and the passage forming member, and is in
contact with the partition surface.
Inventors: |
Inoue; Yoshinori;
(Kariya-shi, JP) ; Mesaki; Hirokazu; (Kariya-shi,
JP) ; Suzuki; Atsuhiro; (Kariya-shi, JP) ;
Kanai; Akinobu; (Kariya-shi, JP) |
Correspondence
Address: |
MORGAN & FINNEGAN, L.L.P.
3 WORLD FINANCIAL CENTER
NEW YORK
NY
10281-2101
US
|
Family ID: |
39015683 |
Appl. No.: |
11/983178 |
Filed: |
November 6, 2007 |
Current U.S.
Class: |
62/228.3 |
Current CPC
Class: |
F25B 49/022 20130101;
F25B 2700/13 20130101; F04B 2205/08 20130101; F04B 27/1804
20130101 |
Class at
Publication: |
62/228.3 |
International
Class: |
F25B 49/02 20060101
F25B049/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 15, 2006 |
JP |
2006-309265 |
Claims
1. A compressor connected to an external refrigerant circuit, the
compressor comprising: a housing; a passage forming member coupled
to an outer surface of the housing, the passage forming member
forming a part of a refrigerant passage connecting the interior of
the housing to the external refrigerant circuit, the refrigerant
passage being comparted into an upstream passage having a high
pressure and a downstream passage having a low pressure; and a
differential pressure type flow rate detector provided in the
passage forming member and obtaining the pressure in the upstream
passage and the pressure in the downstream passage to detect a
refrigerant flow rate within the refrigerant passage, the detector
being provided with an accommodation chamber, a partition body
accommodated within the accommodation chamber such that the
position of the partition body is displaceable, a spring member
urging the partition body, and a stroke defining body accommodated
in the accommodation chamber in such a manner as to define a
maximum stroke amount of the partition body, wherein the partition
body comparts the accommodation chamber into a high pressure
chamber connected to the upstream passage and a low pressure
chamber connected to the downstream passage, the spring member
urging the partition body from the low pressure chamber toward the
high pressure chamber, wherein the stroke defining body exists
closer to the passage forming member than a partition surface
partitioning the housing and the passage forming member, and is in
contact with the partition surface.
2. The compressor according to claim 1, wherein a gasket is
provided between the housing and the passage forming member, and
the partition surface is a seal surface of the gasket opposing to
the passage forming member.
3. The compressor according to claim 1, wherein the partition
surface is an outer surface of the housing.
4. The compressor according to claim 1, wherein the stroke defining
body is made of a synthetic resin, and is fitted to the
accommodation chamber.
5. The compressor according to claim 1, wherein the passage forming
member has a retainer recess, and the stroke defining body is made
of a synthetic resin, and has a retainer projection retained to the
retainer recess.
6. The compressor according to claim 1, wherein the stroke defining
body is made of a synthetic resin, and has an introduction port
passing through the stroke defining body in such a manner as to
connect the low pressure chamber to the downstream passage, and
wherein a filter is provided in the introduction port.
7. The compressor according to claim 1, wherein the stroke defining
body is a spring seat receiving a fixed end of the spring
member.
8. The compressor according to claims 1, the compressor being a
variable displacement compressor that is provided with the
discharge pressure zone, the suction pressure zone, a control
pressure chamber, a supply passage supplying the refrigerant from
the discharge pressure zone to the control pressure chamber, and a
discharge passage discharging the refrigerant from the control
pressure chamber to the suction pressure zone, wherein a
displacement of the compressor is controlled in correspondence to
the pressure within the control pressure chamber.
9. The compressor according to claim 1, wherein the passage forming
member has a restriction passage comparting the refrigerant passage
into the upstream passage and the downstream passage.
10. A compressor connected to an external refrigerant circuit, the
compressor comprising: a housing; a passage forming member coupled
to an outer surface of the housing, the passage forming member
forming a part of a refrigerant passage connecting the interior of
the housing to the external refrigerant circuit, the refrigerant
passage being comparted into an upstream passage having a high
pressure and a downstream passage having a low pressure; a
differential pressure type flow rate detector provided in the
passage forming member and obtaining the pressure in the upstream
passage and the pressure in the downstream passage to detect a
refrigerant flow rate within the refrigerant passage, the detector
being provided with an accommodation chamber, a partition body
accommodated within the accommodation chamber such that the
position of the partition body is displaceable, a spring member
urging the partition body, and a synthetic resin spring seat fitted
to the accommodation chamber in such a manner as to define a
maximum stroke amount of the partition body, wherein the partition
body comparts the accommodation chamber into a high pressure
chamber connected to the upstream passage and a low pressure
chamber connected to the downstream passage, the spring member
urging the partition body from the low pressure chamber toward the
high pressure chamber, wherein the spring member has a fixed end
received by the spring seat; and a gasket provided between the
housing and the passage forming member, the gasket having a seal
surface opposing to the passage forming member, wherein the spring
seat exists closer to the passage forming member than the seal
surface, and is in contact with the seal surface.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a structure for sensing a
flow rate of refrigerant in a compressor.
[0002] Among variable displacement compressors as disclosed in
Japanese Laid-Open Patent Publication No. 2004-197679, there is a
type having a displacement control valve the opening degree of
which is controlled by detecting whether a refrigerant flow rate
flowing through a passage provided within the compressor is proper.
The opening degree of the displacement control valve is changed on
the basis of a differential pressure between both sides of a
restriction in a passage for the refrigerant in the compressor. In
this displacement control valve, a force based on the differential
pressure acts against an electromagnetic force generated by a
current application to a solenoid within the displacement control
valve via a valve body, and the opening degree of the valve is
determined by arranging the valve body at a position where these
two opposing forces are balanced.
[0003] The more the refrigerant flow rate increases, the higher the
differential pressure between both sides of the restriction
becomes. The differential pressure reflects the refrigerant flow
rate, and the opening degree of the displacement control valve is
increased when the differential pressure is increased. If the
refrigerant flow rate becomes more than a proper flow rate, the
opening degree of the displacement control valve is increased, and
the amount of the refrigerant supplied to a crank chamber from a
discharge chamber via a valve hole is increased. Accordingly, the
pressure in the crank chamber is increased, the inclination angle
of a swash plate is decreased, and the refrigerant flow rate is
decreased to be converged into the proper flow rate. If the
refrigerant flow rate becomes smaller than the proper flow rate,
the opening degree becomes small, and the amount of the refrigerant
supplied to the crank chamber from the discharge chamber via the
valve hole is decreased. Accordingly, the pressure in the crank
chamber is decreased, the inclination angle of the swash plate is
increased, and the refrigerant flow rate is increased to be
converged into the proper flow rate.
[0004] In the case that the compressor obtains a driving force from
a vehicle engine, it is necessary to execute an output control of
the engine to achieve an output capable of providing a necessary
torque for driving the compressor. Since the refrigerant flow rate
reflects the torque of the compressor, the torque of the compressor
can be estimated by detecting the refrigerant flow rate. Although
the differential pressure between both sides of the restriction
reflects the refrigerant flow rate, the refrigerant flow rate is
not actually detected. Accordingly, an estimation of the
refrigerant flow rate (that is, the torque of the compressor) is
executed on the basis of a magnitude of an electric current
supplied to the solenoid of the displacement control valve.
[0005] At a time of starting the compressor, an operation control
for setting the displacement to 100% is executed. However, since a
liquid refrigerant in the crank chamber reserved during a stop of
the operation of the compressor is vaporized with the start of the
compressor, the pressure in the crank chamber becomes high, and the
compressor maintains the operation while keeping the inclination
angle of the swash plate small. A state in which the inclination
angle of the swash plate is small corresponds to a state in which
the torque of the compressor is small, that is, a state in which
the refrigerant flow rate is small. On the other hand, the
refrigerant flow rate estimated from the electric current supplied
to the solenoid is large. Accordingly, even though the torque of
the compressor is actually small, the operation of the vehicle
engine is controlled on the assumption that the torque of the
compressor is large. This causes an energy loss.
[0006] Accordingly, it is desirable to detect a refrigerant flow
rate discharged from the compressor by using a differential
pressure type flow rate detector as disclosed in Japanese Laid-Open
Utility Model Publication No. 63-177715. The flow rate detector
outputs an electric signal in correspondence to the differential
pressures on both sides of a restriction. In FIG. 2 of the
publication, the pressures on both sides of the restriction are
opposed to each other via a bellofram (a partition body), and a
force on the basis of the differential pressures opposes to a
spring force of a coil spring. The bellofram is arranged at a
position at which the differential pressures and the spring force
are balanced, and an electric signal in correspondence to the
position of a permanent magnet integrally displaced with the
bellofram is output from a hall element.
[0007] It is desirable that the flow rate detector be provided not
in a compressor housing, but in a passage forming member coupled to
the compressor housing in such a manner as to form a part of the
refrigerant passage. If the flow rate detector is provided in the
passage forming member, it is possible to regulate and calibrate
the flow rate detector in a state in which the passage forming
member is detached from the compressor housing. Accordingly, it is
possible to easily regulate and calibrate the flow rate detector in
comparison with the case that the flow rate detector is provided
within the compressor housing.
[0008] In the case that the passage forming member is detached from
the compressor housing for regulating and calibrating the flow rate
detector, it is necessary to prevent the partition body, the coil
spring, the permanent magnet, which are components of the flow rate
detector from falling off an accommodation chamber accommodating
these components. The components are prevented from falling off,
for example, by fastening a spring seat for the coil spring to the
passage forming member by press fitting the spring seat for the
coil spring to the accommodation chamber in such a manner as to
confine the partition body, the coil spring, the permanent magnet
or the like in the accommodation chamber.
[0009] In the case that a coil spring having a large wire diameter
and a large spring constant is employed for the flow rate detector,
the minimum length (a length which cannot be compressed any more)
of the coil spring becomes enlarged. Accordingly, in order to
secure a contraction and expansion amount (that is, the maximum
stroke of the partition body and the permanent magnet) of the coil
spring within the accommodation chamber large, it is necessary to
enlarge the free length of the coil spring. In order to enlarge the
free length of the coil spring, it is necessary to enlarge the
length of an accommodating space accommodating the coil spring, the
partition body and the permanent magnet, that is, the size of the
accommodating space in a contracting and expanding direction of the
coil spring. Therefore, it is preferable to make the thickness of
the spring seat in the contracting and expanding direction of the
coil spring small. However, in the case of reducing the thickness
of the spring seat, a press fitting margin needs to be created
between the spring seat and a wall surface of the accommodation
chamber to obtain a necessary fastening force. If the press fitting
margin is set large, the wall surface of the accommodation chamber
may be largely deformed.
SUMMARY OF THE INVENTION
[0010] Accordingly, it is an objective of the present invention to
enlarge the length of an accommodation space of a spring member
without hindrance in a compressor provided with a differential
pressure type flow rate detector in a passage forming body coupled
to an outer surface of the compressor.
[0011] In order to achieve the object mentioned above, in
accordance with an aspect of the present invention, a compressor
connected to an external refrigerant circuit is provided. The
compressor includes a housing, a passage forming member, and a
differential pressure type flow rate detector. The passage forming
member is coupled to an outer surface of the housing. The passage
forming member forms a part of a refrigerant passage that connects
the interior of the housing to the external refrigerant circuit.
The refrigerant passage is comparted into an upstream passage
having a high pressure and a downstream passage having a low
pressure. The differential pressure type flow rate detector is
provided in the passage forming member and obtains the pressure in
the upstream passage and the pressure in the downstream passage to
detect a refrigerant flow rate within the refrigerant passage. The
detector is provided with an accommodation chamber, a partition
body accommodated within the accommodation chamber such that the
position of the partition body is displaceable, a spring member
that urges the partition body, and a stroke defining body
accommodated in the accommodation chamber in such a manner as to
define a maximum stroke amount of the partition body. The partition
body comparts the accommodation chamber into a high pressure
chamber connected to the upstream passage and a low pressure
chamber connected to the downstream passage. The spring member
urges the partition body from the low pressure chamber toward the
high pressure chamber. The stroke defining body exists closer to
the passage forming member than a partition surface that partitions
the housing and the passage forming member, and is in contact with
the partition surface.
[0012] Other aspects and advantages of the present invention will
become apparent from the following description, taken in
conjunction with the accompanying drawings, illustrating by way of
example the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] 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:
[0014] FIG. 1 is a cross-sectional side view of a whole of a
variable displacement compressor in accordance with a first
embodiment of the present invention;
[0015] FIG. 2A is a partially enlarged cross-sectional side view of
the compressor in FIG. 1;
[0016] FIG. 2B is a view showing a portion surrounded by a circle
2B in FIG. 2A in a further enlarged manner;
[0017] FIG. 3 is a cross-sectional view taken along line 3-3 in
FIG. 1;
[0018] FIG. 4 is a cross-sectional view taken along line 4-4 in
FIG. 2A;
[0019] FIG. 5 is a cross-sectional view taken along line 5-5 in
FIG. 2A;
[0020] FIG. 6 is a cross-sectional view taken along line 6-6 in
FIG. 2A;
[0021] FIG. 7A is a partially cross-sectional side view of a
compressor in accordance with a second embodiment of the present
invention;
[0022] FIG. 7B is a partially enlarged cross-sectional side view of
FIG. 7A; and
[0023] FIG. 8 is a partially cross-sectional side view of a
compressor in accordance with a third embodiment of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] A description will be given of a first embodiment obtained
by embodying the present invention with reference to FIGS. 1 to
8.
[0025] As shown in FIG. 1, a housing of a variable displacement
compressor 10 is provided with a cylinder block 11, a front housing
member 12 connected to a front end of the cylinder block 11, and a
rear housing member 13 connected to a rear end of the cylinder
block 11 via a valve plate 14, valve forming plates 15 and 16 and a
retainer forming plate 17. The cylinder block 11, the front housing
member 12, and the rear housing member 13 construct the housing of
the compressor 10.
[0026] The front housing member 12 and the cylinder block 11 form a
control pressure chamber 121. A rotary shaft 18 is rotatably
supported to the front housing member 12 and the cylinder block 11
respectively via radial bearings 19 and 20. The rotary shaft 18
protrudes to the outside from the control pressure chamber 121, and
obtains a driving force from a vehicle engine E serving as an
external driving source.
[0027] A rotary support 21 is fixed to the rotary shaft 18, and a
swash plate 22 is supported thereto so as to be slidable in an
axial direction and tiltable. A guide pin 23 provided in the swash
plate 22 is slidably fitted to a guide hole 211 formed in the
rotary support 21. The swash plate 22 is movable in the axial
direction of the rotary shaft 18 while being tilted and is
integrally rotatable with the rotary shaft 18, on the basis of the
link between the guide hole 211 and the guide pin 23. The tilting
motion of the swash plate 22 is generated by a sliding motion of
the guide pin 23 with respect to the guide hole 211 and a sliding
motion of the swash plate 22 with respect to the rotary shaft
18.
[0028] If a radial center of the swash plate 22 is moved toward the
rotary support 21, the inclination angle of the swash plate 22 is
increased. The maximum inclination angle of the swash plate 22 is
regulated by contact between the rotary support 21 and the swash
plate 22. The swash plate 22 shown by a solid line in FIG. 1 is
under a state of the maximum inclination angle, and the swash plate
22 shown by a chain line is under a state of the minimum
inclination angle.
[0029] A piston 24 is accommodated within each of a plurality of
cylinder bores 111 formed through the cylinder block 11. Rotation
of the swash plate 22 is converted into reciprocation of the
pistons 24 by means of shoes 25, and the pistons 24 reciprocate
within the cylinder bores 111.
[0030] A suction chamber 131 and a discharge chamber 132 are
defined within the rear housing member 13. The suction chamber 131
corresponds to a suction pressure zone, and the discharge chamber
132 corresponds to a discharge pressure zone. Suction ports 141 are
formed in the valve plate 14, the valve forming plate 16, and the
retainer forming plate 17 in such a manner as to correspond to the
respective cylinder bores 111. Discharge ports 142 are formed in
the valve plate 14 and the valve forming plate 15 in such a manner
as to correspond to the respective cylinder bores 111. Suction
valve flaps 151 are formed in the valve forming plate 15 in such a
manner as to correspond to the respective suction ports 141, and
discharge valve flaps 161 are formed in the valve forming plate 16
in such a manner as to correspond to the respective discharge ports
142. Refrigerant within the suction chamber 131 pushes each suction
valve flap 151 through the corresponding suction port 141 by a
movement from the top dead center toward the bottom dead center of
the associated piston 24 (the movement from right to left in FIG.
1), and flows into the cylinder bore 111. The refrigerant gas
flowing into the cylinder bore 111 pushes each discharge valve flap
161 through the corresponding discharge port 142 by a movement from
the bottom dead center toward the top dead center of the associated
piston 24 (the movement from left to right in FIG. 1), and is
discharged to the discharge chamber 132. The opening degree of each
discharge valve flap 161 is regulated by contact of the discharge
valve flap 161 with a retainer 171 on the retainer forming plate
17.
[0031] An electromagnetic type displacement control valve 26 is
assembled in the rear housing member 13. The displacement control
valve 26 is provided on a supply passage 27 connecting the
discharge chamber 132 and the control pressure chamber 121. The
opening degree of the displacement control valve 26 is adjusted in
correspondence to the pressure of the suction chamber 131 and a
duty ratio of a current applied to an electromagnetic solenoid (not
shown) of the displacement control valve 26. When a valve hole of
the displacement control valve 26 is closed, the refrigerant within
the discharge chamber 132 is not fed to the control pressure
chamber 121.
[0032] The control pressure chamber 121 is connected to the suction
chamber 131 via a discharge passage 28, and the refrigerant within
the control pressure chamber 121 flows out to the suction chamber
131 via the discharge passage 28. If the opening degree of the
displacement control valve 26 becomes large, the amount of the
refrigerant flowing into the control pressure chamber 121 from the
discharge chamber 132 via the supply passage 27 is increased, and
the pressure in the control pressure chamber 121 is increased.
Accordingly, the inclination angle of the swash plate 22 is
decreased, and the displacement of the compressor is decreased. If
the opening degree of the displacement control valve 26 becomes
small, the amount of the refrigerant flowing into the control
pressure chamber 121 from the discharge chamber 132 via the supply
passage 27 is decreased, and the pressure in the control pressure
chamber 121 is decreased. Accordingly, the inclination angle of the
swash plate 22 is increased, and the displacement of the compressor
is increased.
[0033] A protruding pedestal 29 is integrally formed in an upper
portion of an outer circumferential surface 110 of the cylinder
block 11. As shown in FIG. 2A, an upper end 291 of the pedestal 29,
that is, an outer surface of the cylinder block 11 is flat, and a
muffler forming member 30 serving as a passage forming member is
coupled to the upper end 291 of the pedestal 29 with a tabular
sealing gasket 31. The gasket 31 is structured by rubber layers 312
and 313 baked on both surfaces of a metal plate 311, which is a
core material (refer to FIG. 2B). The gasket 31 prevents
refrigerant leakage from a portion between the pedestal 29 and the
muffler forming member 30. As shown in FIG. 3, the muffler forming
member 30 and the gasket 31 are both fixed to the pedestal 29 by a
screw 32.
[0034] A muffler chamber 33 and an accommodation chamber 34 are
formed in the muffler forming member 30, and a partition body 35 is
slidably accommodated in the accommodation chamber 34, which is
open toward the pedestal 29. That is, the position of the partition
body 35 is displaceable within the accommodation chamber 34. The
partition body 35 comparts the accommodation chamber 34 into a high
pressure chamber 341 and a low pressure chamber 342. A spring seat
36 made of a synthetic resin is fitted to an opening of the
accommodation chamber 34, and a coil spring 37 serving as a spring
member is arranged between the partition body 35 and the
ring-shaped spring seat 36. The coil spring 37 urges the partition
body 35 from the low pressure chamber 342 toward the high pressure
chamber 341.
[0035] The spring seat 36 serving as a stroke defining body is
provided with a disc-shaped base portion 45 and a cylindrical
portion 46, and a fixed end 371 of the coil spring 37 comes into
contact with the base portion 45. A back surface 451 of the base
portion 45 comes into contact with a surface of the rubber layer
312, that is, a seal surface 310. Introduction ports 461 are formed
in the cylindrical portion 46. An annular communication groove 343
is formed in a peripheral wall surface 344 of the accommodation
chamber 34. The introduction port 461 connects an internal space of
the cylindrical portion 46, specifically the low pressure chamber
342, with the communication groove 343. The introduction port 461
is covered by an annular filter 53 surrounding an outer peripheral
portion of the cylindrical portion 46. The spring seat 36 is
insert-molded in a state in which the filter 53 is put into the
mold.
[0036] The low pressure chamber 342 communicates with the muffler
chamber 33 via the introduction port 461 and the communication
groove 343. The pressure within the muffler chamber 33 is applied
to the low pressure chamber 342.
[0037] A permanent magnet 351 is fixed to the partition body 35,
and a magnetic detector 38 is provided on an outer surface of the
muffler forming member 30. The magnetic detector 38 detects a
magnetic flux density of the permanent magnet 351. Information
about the magnetic flux density detected by the magnetic detector
38 is transmitted to a displacement control computer C1 shown in
FIG. 1.
[0038] As shown in FIG. 2A, an oil separator 39 is installed in the
rear housing member 13. The oil separator 39 is provided with a
housing 40. A refrigerant swirling cylinder 41 is fitted into the
housing 40 and fixed inside the housing 40. The cylinder 41
comparts the housing 40 into an oil separating chamber 42 and a
passing chamber 43, and the oil separating chamber 42 is connected
to the discharge chamber 132 via an introduction passage 44. The
refrigerant within the discharge chamber 132 flows into the oil
separating chamber 42 via the introduction passage 44. The
refrigerant flowing into the oil separating chamber 42 from the
introduction passage 44 is swirled along an outer circumferential
surface of the cylinder 41 around the cylinder 41. The refrigerant
swirling around the cylinder 41 flows out to the passing chamber 43
via an internal space 411 of the cylinder 41.
[0039] A passage 47 passing through the valve plate 14 and the
gasket 31 is formed in the muffler forming member 30, the cylinder
block 11, and the rear housing member 13. The muffler chamber 33 is
connected to the passage 47 within the muffler forming member 30
via the restriction passage 50, and the passage 47 is connected to
the passing chamber 43. FIG. 4 shows the passage 47 formed in the
cylinder block 11, FIG. 5 shows the passage 47 provided in a
penetrating manner in the gasket 31, and FIG. 6 shows the passage
47 and the restriction passage 50 formed in the muffler forming
member 30.
[0040] As shown in FIGS. 2A and 3, an oil reservoir chamber 48 is
formed within the pedestal 29. The oil reservoir chamber 48 is
isolated from the muffler chamber 33 and an accommodation chamber
34 by the gasket 31. As shown in FIG. 2A, the oil reservoir chamber
48 is connected to the oil separating chamber 42 via a passage 49
formed in the cylinder block 11, the valve plate 14 and the rear
housing member 13.
[0041] The refrigerant within the discharge chamber 132 shown in
FIG. 1 flows out to an external refrigerant circuit 51 via the
introduction passage 44, the interior of the oil separator 39, the
passage 47, restriction passage 50, and the muffler chamber 33. The
refrigerant flowing out to the external refrigerant circuit 51 is
circulated to the suction chamber 131. On the external refrigerant
circuit 51, there are provided a heat exchanger 54 for absorbing
heat from the refrigerant, an expansion valve 55, and a heat
exchanger 56 for transferring the surrounding heat to the
refrigerant. The expansion valve 55 controls a refrigerant flow
rate in correspondence to fluctuations of the gas temperature in an
outlet side of the heat exchanger 56. Oil exists in a circuit
comprising the variable displacement compressor 10 and the external
refrigerant circuit 51, and the oil flows with the refrigerant.
[0042] The refrigerant flowing into the oil separating chamber 42
from the discharge chamber 132 via the introduction passage 44
shown in FIG. 2A swirls along the outer circumferential surface of
the cylinder 41 around the cylinder 41. Accordingly, mist-like oil
contained in the refrigerant is separated from the refrigerant
within the oil separating chamber 42. The refrigerant swirling
around the cylinder 41 flows into an internal space 411 of the
cylinder 41, and the oil separated from the refrigerant flows into
the oil reservoir chamber 48 via the passage 49. The oil within the
oil reservoir chamber 48 flows out to the control pressure chamber
121 via a return passage 57 open to a bottom portion of the oil
reservoir chamber 48. The oil within the control pressure chamber
121 is used for lubricating a sliding portion within the control
pressure chamber 121.
[0043] The restriction passage 50 generates a difference between
the pressure within the passage 47 and the pressure within the
muffler chamber 33. The pressure within the muffler chamber 33 is
lower than the pressure within the passage 47. The introduction
passage 44, the oil separating chamber 42, the passing chamber 43,
the passage 47, the restriction passage 50, and the muffler chamber
33 construct a refrigerant passage 52 through which the refrigerant
discharged out of the housing from the interior of the housing of
the variable displacement compressor 10 passes. The refrigerant
passage 52 is comparted into an upstream passage 58 including the
introduction passage 44, the oil separating chamber 42, the passing
chamber 43 and the passage 47, and the muffler chamber 33 serving
as a downstream passage, by the restriction passage 50.
[0044] The pressure within the upstream passage 58 is applied to
the high pressure chamber 341 via a high pressure introduction
passage 59 formed in the muffler forming member 30, and the
pressure within the muffler chamber 33 serving as the downstream
passage is applied to the low pressure chamber 342 via the
communication groove 343 and an introduction port 461. The pressure
within the high pressure chamber 341 and the pressure within the
low pressure chamber 342 oppose to each other with the partition
body 35 in between. The differential pressure between the pressure
within the high pressure chamber 341 and the pressure within the
low pressure chamber 342 acts against the spring force of the coil
spring 37, and the partition body 35 is arranged at a position at
which the force based on the differential pressure and the spring
force of the coil spring 37 are balanced. The permanent magnet 351
fixed to the partition body 35 is separated away from the magnetic
detector 38 as the differential pressure between the pressure
within the high pressure chamber 341 and the pressure within the
low pressure chamber 342 increases. In the case that the
differential pressure does not exist between the high pressure
chamber 341 and the low pressure chamber 342, the coil spring 37 is
in a state close to the free length, and the partition body 35
comes into contact with the bottom 340 of the accommodation chamber
34.
[0045] If the flow rate of the refrigerant flowing through the
refrigerant passage 52 is increased, the differential pressure is
increased, and the partition body 35 is displaced from the high
pressure chamber 341 toward the low pressure chamber 342. If the
flow rate of the refrigerant flowing through the refrigerant
passage 52 is decreased, the differential pressure is decreased,
and the partition body 35 is displaced from the low pressure
chamber 342 toward the high pressure chamber 341. The position of
the partition body 35 is reflected to the magnetic flux density
detected by the magnetic detector 38. The magnetic flux density
detected by the magnetic detector 38 reflects the position of the
partition body 35, that is, the flow rate of the refrigerant
flowing through the refrigerant passage 52.
[0046] The accommodation chamber 34, the partition body 35, the
coil spring 37, the spring seat 36, and the magnetic detector 38
form a differential pressure type flow rate detector 60 that
obtains the pressure in the upstream passage 58 and the pressure in
the downstream passage (the muffler chamber 33), thereby detecting
the flow rate of the refrigerant within the refrigerant passage
52.
[0047] As shown in FIG. 1, a room temperature setting device 61 and
a room temperature detector 62 are connected to the displacement
control computer C1. The displacement control computer C1 controls
a current supplied to the electromagnetic solenoid of the
displacement control valve 26 on the basis of the magnetic flux
density information obtained by the magnetic detector 38 in such a
manner that the room temperature detected by the room temperature
detector 62 is converged into a target room temperature set by the
room temperature setting device 61. That is, the displacement
control computer C1 executes a feedback control for controlling the
flow rate of the refrigerant to achieve a proper value on the basis
of the magnetic flux density information obtained by the magnetic
detector 38.
[0048] The displacement control computer C1 transmits the torque
information of the variable displacement compressor 10 to an engine
control computer C2 on the basis of the magnetic flux density
information obtained from the magnetic detector 38. The engine
control computer C2 executes a proper control of the speed of the
vehicle engine E on the basis of the torque information obtained
from the displacement control computer C1.
[0049] The present embodiment in detail mentioned above has the
following advantages.
[0050] (1) It is possible to regulate and calibrate the
differential pressure type flow rate detector 60 assembled in the
muffler forming member 30 in a state in which the muffler forming
member 30 is detached from the housing (specifically, from the
cylinder block 11) of the variable displacement compressor 10. In
this case, the structure is made such as to prevent the position of
the spring seat 36 from being changed by using a jig.
[0051] In the case of moving the muffler forming member 30 detached
form the cylinder block 11 to a place for regulating and
calibrating, it is necessary to prevent the spring seat 36, the
partition body 35 and the coil spring 37 from falling off the
accommodation chamber 34. In a state in which the partition body 35
is in contact with the bottom 340 of the accommodation chamber 34,
the coil spring 37 is in a state close to the free length, and the
spring force of the coil spring 37 applied to the spring seat 36 is
small. Accordingly, in a state in which the muffler forming member
30 is away from the cylinder block 11, it is possible to make the
fastening force to the spring seat 36 necessary for preventing the
spring seat 36 from falling off the muffler forming member 30,
(that is, the force for fastening and holding the spring seat 36 at
a time of fitting the spring seat 36 to the accommodation chamber
34) small.
[0052] In the state in which the muffler forming member 30 is
fastened to the cylinder block 11, the spring seat 36 exists at the
position of being in contact with the gasket 31. Accordingly, it is
possible to utilize the space within the accommodation chamber 34
as an accommodation space for the partition body 35 and the coil
spring 37 to the maximum. In other words, it is possible to enlarge
without hindrance the length of the accommodation space for the
coil spring 37, that is, the size of the accommodation space in the
contracting and expanding direction of the coil spring 37, without
employing the structure for strongly press fitting the spring seat
36 to the accommodation chamber 34 so as to cause a deformation of
the peripheral wall surface 344 of the accommodation chamber 34. In
other words, it is possible to enlarge the maximum stroke amount of
the partition body 35 without hindrance.
[0053] (2) Since the spring seat 36 is in contact with the gasket
31, the spring seat 36 is hardly deformed by the pressure of the
refrigerant and the spring force of the coil spring 37.
Accordingly, it is possible to reduce the thickness of the base
portion 45 of the spring seat 36, and it is possible to utilize the
space within the accommodation chamber 34 as the accommodation
space for the partition body 35 and the coil spring 37 to the
maximum.
[0054] (3) The gasket 31 partitions the cylinder block 11 and the
muffler forming member 30, and the seal surface 310 of the gasket
31 is a partition surface partitioning the cylinder block 11 and
the muffler forming member 30. The gasket 31, which ensures a
sealing performance between the cylinder block 11 and the muffler
forming member 30 and partitions the cylinder block 11 and the
muffler forming member 30, is a suitable member for receiving and
holding the spring seat 36 so as to secure the length of the
accommodation space of the coil spring 37.
[0055] (4) The fastening force utilizing the elastic deforming
force of the synthetic resin is suitable for generating a weak
fastening force which does not generate deformation of the
peripheral wall surface 344 of the accommodation chamber 34. In
other words, it is preferable for obtaining the weak fastening
force to form the spring seat 36 by the synthetic resin, and it is
preferable for saving weight of the spring seat 36.
[0056] (5) Since the spring seat 36 is not displaced on the basis
of the contact with the gasket 31, the detection accuracy is not
lowered due to the displacement of the spring seat 36.
[0057] (6) If foreign matter enters a portion between the partition
body 35 and the peripheral wall surface 344 of the accommodation
chamber 34, a portion between the partition body 35 and the
peripheral wall surface 344 of the accommodation chamber 34 is
damaged. The filter 53, which removes such foreign matter can be
easily provided in the spring seat 36 by insert molding the spring
seat 36 made of the synthetic resin.
[0058] (7) The pressure in the muffler chamber 33 is introduced to
the low pressure chamber 342 connected to the muffler chamber 33.
The passage structure for connecting the low pressure chamber 342
to the muffler chamber 33 is simple, and the structure in which the
muffler chamber 33 is formed as the downstream passage of the
refrigerant passage 52 simplifies the passage structure for
introducing the pressure in the downstream passage to the
differential pressure type flow rate detector 60 provided in the
muffler forming member 30.
[0059] Next, a description will be given of a second embodiment
according to the present invention with reference to FIG. 7. Some
of the reference numerals used in the previous description will be
used below, and a description of the common structure will be
omitted. Description will be given only of the modified
portions.
[0060] In the second embodiment, the oil separator 39 and the oil
reservoir chamber 48 in the first embodiment are not provided.
Further, the spring seat 36 made of the synthetic resin is in
contact with an upper end 291 of the pedestal 29. A retainer
projection 462 is integrally formed in an outer circumferential
surface of the cylindrical portion 46 of the spring seat 36, and a
retainer recess 345 is formed in the peripheral wall surface 344 of
the accommodation chamber 34. At a time when the spring seat 36 is
fitted to the accommodation chamber 34, the retainer projection 462
enters into a position of the retainer recess 345 while being
elastically deformed, and the retainer projection 462 is retained
to the retainer recess 345.
[0061] Since the retainer projection 462 can be molded at the same
time of molding the spring seat 36 made of the synthetic resin
which can be molded into a complex shape, it is possible to easily
mold the retainer projection 462. The force required for
elastically deforming the retainer projection 462 is comparatively
small, and does not deform the peripheral wall surface 344 of the
accommodation chamber 34.
[0062] The base portion 45 of the spring seat 36 is in contact with
the cylinder block 11, and the outer surface of the cylinder block
11 (the upper end 291 of the pedestal 29) serves as a partition
surface partitioning the cylinder block 11 and the muffler forming
member 30. In the structure in which the outer surface of the
cylinder block 11 is formed as the partition surface, it is
possible to elongate the length of the accommodation space of the
coil spring 37 by the amount corresponding to the thickness of the
gasket 31, in comparison with the structure in which the seal
surface 310 of the gasket 31 is formed as the partition
surface.
[0063] Next, a description will be given of a third embodiment
according to the present invention with reference to FIG. 8. Some
of the reference numerals used in the previous description will be
used below, and a description of the common structure will be
omitted. Description will be given only of the modified
portions.
[0064] A partition body 35B of a differential pressure type flow
rate detector 60B comparts an accommodation chamber 34B into a high
pressure chamber 341B and a low pressure chamber 342B, and a coil
spring 37B serving as a spring member is accommodated in the low
pressure chamber 342B. A positioning seat 63 serving as the stroke
defining body is fitted to the accommodation chamber 34B, and the
coil spring 37B urges the partition body 35B toward the positioning
seat 63. The positioning seat 63 made of the synthetic resin is
fitted to the accommodation chamber 34B and is in contact with the
gasket 31.
[0065] The high pressure chamber 341B is connected to a passage 47B
via an introduction port 631 formed in the positioning seat 63, the
communication groove 343, the muffler forming member 30, and the
passage 64 formed in the gasket 31. The low pressure chamber 342B
is connected to the muffler chamber 33 via the low pressure
introduction passage 301 formed in the muffler forming member 30.
The muffler chamber 33 is connected to the passage 47B via the
restriction 65 formed in the gasket 31. The introduction port 631
is covered by the filter 53.
[0066] The restriction 65 comparts the refrigerant passage 52B into
the upstream passage and the downstream passage, and generates a
differential pressure between the pressure within the passage 47B
and the pressure within the muffler chamber 33. The pressure within
the passage 47B is applied to the high pressure chamber 341B, and
the pressure within the muffler chamber 33 is applied to the low
pressure chamber 342B. The permanent magnet 351 fastened to the
partition body 35B comes closer to the magnetic detector 38 as the
differential pressure between the pressure within the high pressure
chamber 341B and the pressure within the low pressure chamber 342B
increases. In the case that the differential pressure does not
exist between the high pressure chamber 341B and the low pressure
chamber 342B, the partition body 35B comes into contact with the
positioning seat 63.
[0067] In accordance with the third embodiment mentioned above, it
is possible to obtain the same advantages as the advantages (1) to
(7) of the first embodiment mentioned above.
[0068] Each of the embodiments mentioned above may be modified as
follows.
[0069] In the first to third embodiments mentioned above, the
muffler forming member 30 is coupled to the pedestal 29 of the
cylinder block 11 via the gasket 31. However, the muffler forming
member 30 may be coupled to the outer circumferential surface of
the front housing member 12 or the outer circumferential surface of
the rear housing member 13. Alternatively, the muffler forming
member 30 may be coupled to an outer circumferential surface which
is astride two members or more in the cylinder block 11, the front
housing member 12 and the rear housing member 13.
[0070] A bellows may be used as the partition body in the
differential pressure type flow rate detector.
[0071] A diaphragm may be used as the partition body in the
differential pressure type flow rate detector.
[0072] The structure may be made such that a passage forming member
is provided between the external refrigerant circuit 51 and the
suction chamber 131, a gasket is provided between the housing of
the variable displacement compressor and the passage forming
member, and a differential pressure type flow rate detector is
provided in the passage forming member. The differential pressure
type flow rate detector in this case detects the refrigerant flow
rate flowing into the suction chamber 131 from the external
refrigerant circuit 51.
[0073] The present invention may be applied to a fixed displacement
type compressor.
[0074] It should be apparent to those skilled in the art that the
present invention may be embodied in many other specific forms
without departing from the spirit or scope of the invention.
Particularly, it should be understood that the invention may be
embodied in the following forms.
[0075] The present examples and embodiments are to be considered as
illustrative and not restrictive and the invention is not to be
limited to the details given herein, but may be modified within the
scope and equivalence of the appended claims.
* * * * *