U.S. patent application number 10/728346 was filed with the patent office on 2004-08-26 for displacement varying structure of variable displacement compressor.
Invention is credited to Hashimoto, Yuji, Hirose, Tatsuya, Matsubara, Ryo, Suzuki, Junya, Umemura, Satoshi.
Application Number | 20040165994 10/728346 |
Document ID | / |
Family ID | 32322052 |
Filed Date | 2004-08-26 |
United States Patent
Application |
20040165994 |
Kind Code |
A1 |
Umemura, Satoshi ; et
al. |
August 26, 2004 |
Displacement varying structure of variable displacement
compressor
Abstract
A control valve includes a separation portion, which is part of
a rod, blocks a through hole that connects a valve chamber and a
second chamber with each other. Therefore, the pressure of the
second chamber is not directly affected by changes in the opening
degree of the control valve. The second chamber and a valve hole
forming a part of the through hole are both connected to a second
pressure zone through an upstream section of a supply passage. This
prevents creation of pressure difference between the valve hole and
the second chamber, and thus prevents entry of foreign particles in
sliding portions between the through hole and the rod.
Inventors: |
Umemura, Satoshi;
(Kariya-shi, JP) ; Hirose, Tatsuya; (Kariya-shi,
JP) ; Hashimoto, Yuji; (Kariya-shi, JP) ;
Matsubara, Ryo; (Kariya-shi, JP) ; Suzuki, Junya;
(Kariya-shi, JP) |
Correspondence
Address: |
WOODCOCK WASHBURN LLP
ONE LIBERTY PLACE, 46TH FLOOR
1650 MARKET STREET
PHILADELPHIA
PA
19103
US
|
Family ID: |
32322052 |
Appl. No.: |
10/728346 |
Filed: |
December 4, 2003 |
Current U.S.
Class: |
417/222.2 |
Current CPC
Class: |
F04B 2027/1831 20130101;
F04B 27/1804 20130101 |
Class at
Publication: |
417/222.2 |
International
Class: |
F04B 001/26 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 12, 2002 |
JP |
2002-355593 |
Claims
1. A displacement varying structure of a variable displacement
compressor that is installed in a refrigerant circuit, wherein the
refrigerant circuit has a discharge pressure zone and a suction
pressure zone, wherein the variable displacement compressor has a
crank chamber, and wherein the displacement varying structure is
capable of varying a displacement of the variable displacement
compressor by changing a pressure of the crank chamber, the
displacement varying structure comprising: a supply passage for
connecting the crank chamber with the discharge pressure zone; a
bleed passage for connecting the crank chamber with the suction
pressure zone; and a control valve located in a control passage,
the control passage being one of the supply passage and the bleed
passage, wherein the control valve includes: a valve housing
defining a valve chamber, a valve hole, and a pressure sensing
chamber, wherein the valve chamber and the valve hole form a part
of the control passage; a valve body accommodated in the valve
chamber, wherein the valve body is capable of being displaced, and
wherein the valve body adjusts an opening degree of the valve hole
in accordance with the position of the valve body in the valve
chamber; a pressure sensing member accommodated in the pressure
sensing chamber, wherein the pressure sensing member divides the
pressure sensing chamber into a first chamber and a second chamber,
and wherein the pressure sensing member is capable of being
displaced in accordance with a pressure difference between the
first chamber and the second chamber; a separation wall that
separates in the valve housing the valve chamber and the pressure
sensing chamber from each other, wherein the separation wall has a
through hole for connecting the valve chamber and the second
chamber with each other; a rod that extends through the through
hole and connects the pressure sensing member and the vale body
with each other, wherein the rod has a separation portion that
blocks connection between the valve chamber and the second chamber
through the through hole; and an adjacent zone that is adjacent to
the second chamber with the separation portion in between, wherein,
if a part of the through hole that is closer to the valve chamber
than the separation portion and opens to the valve chamber forms
the valve hole, the valve hole is the adjacent zone, and if the
valve hole is located at the opposite side of the valve chamber
with respect to the second chamber, the valve chamber is the
adjacent zone, and wherein the adjacent zone and the second chamber
are connected to a common pressure zone in the refrigerant
circuit.
2. The displacement varying structure according to claim 1, wherein
the control passage is the supply passage, and the discharge
pressure zone includes a first pressure zone and a second pressure
zone, wherein the pressure of the first pressure zone is higher
than the pressure of the second pressure zone, and wherein the
first chamber is connected to one of the first and second pressure
zones, and the second chamber and the adjacent zone are connected
to the other one of the first and second pressure zones.
3. The displacement varying structure according to claim 2, wherein
a restrictor is provided in the discharge pressure zone, and
wherein a section of the discharge pressure zone that is upstream
of the restrictor comprises the first pressure zone, and a section
of the discharge pressure zone that is downstream of the restrictor
comprises the second pressure zone.
4. The displacement varying structure according to claim 1, wherein
the control passage is the bleed passage, and the suction pressure
zone includes a first pressure zone and a second pressure zone,
wherein the pressure of the first pressure zone is higher than the
pressure of the second pressure zone, and wherein the first chamber
is connected to one of the first and second pressure zones, and the
second chamber and the adjacent zone are connected to the other one
of the first and second pressure zones.
5. The displacement varying structure according to claim 4, wherein
a restrictor is provided in the suction pressure zone, and wherein
a section of the suction pressure zone that is upstream of the
restrictor comprises the first pressure zone, and a section of the
suction pressure zone that is downstream of the restrictor
comprises the second pressure zone.
6. The displacement varying structure according to claim 1, wherein
the compressor has a compressor housing in which an accommodation
recess is formed, wherein the control valve is inserted in the
accommodation recess, and wherein the second chamber and the
adjacent zone are connected to each other through a space defined
between an inner surface of the accommodation recess and an outer
surface of the valve housing.
7. The displacement varying structure according to claim 1, wherein
a connecting passage for connecting the second chamber to the
adjacent zone is formed in the valve housing.
8. The displacement varying structure according to claim 1, wherein
the control valve has an actuator, and wherein, based on an
external command, the actuator changes a force applied to the valve
body.
9. A refrigerant-circuit containing a variable displacement
compressor, wherein the variable displacement compressor has a
crank chamber, and a displacement of the variable displacement
compressor is varied by changing a pressure of the crank chamber,
the refrigerant circuit comprising: a discharge pressure zone; a
suction pressure zone; a supply passage for connecting the crank
chamber with the discharge pressure zone; a bleed passage for
connecting the crank chamber with the suction pressure zone; and a
control valve located in a control passage, the control passage
being one of the supply passage and the bleed passage, wherein the
control valve includes: a valve housing defining a valve chamber, a
valve hole, and a pressure sensing chamber, wherein the valve
chamber and the valve hole form a part of the control passage; a
valve body accommodated in the valve chamber, wherein the valve
body is capable of being displaced, and wherein the valve body
adjusts an opening degree of the valve hole in accordance with the
position of the valve body in the valve chamber; a pressure sensing
member accommodated in the pressure sensing chamber, wherein the
pressure sensing member divides the pressure sensing chamber into a
first chamber and a second chamber, and wherein the pressure
sensing member is capable of being displaced in accordance with a
pressure difference between the first chamber and the second
chamber; a separation wall that separates in the valve housing the
valve chamber and the pressure sensing chamber from each other,
wherein the separation wall has a through hole for connecting the
valve chamber and the second chamber with each other; and a rod
that extends through the through hole and connects the pressure
sensing member and the vale body with each other, wherein the rod
has a separation portion that blocks connection between the valve
chamber and the second chamber through the through hole, wherein a
part of the through hole that is closer to the valve chamber than
the separation portion and opens to the valve chamber forms the
valve hole, and wherein the valve hole and the second chamber are
connected to a common pressure zone in the refrigerant circuit.
10. The refrigerant circuit according to claim 9, wherein the
control passage is the supply passage, and the discharge pressure
zone includes a first pressure zone and a second pressure zone,
wherein the pressure of the first pressure zone is higher than the
pressure of the second pressure zone, and wherein the first chamber
is connected to one of the first and second pressure zones, and the
second chamber and the valve hole are connected to the other one of
the first and second pressure zones.
11. The refrigerant circuit according to claim 10, wherein a
restrictor is provided in the discharge pressure zone, and wherein
a section of the discharge pressure zone that is upstream of the
restrictor comprises the first pressure zone, and a section of the
discharge pressure zone that is downstream of the restrictor
comprises the second pressure zone.
12. The refrigerant circuit according to claim 9, wherein the
control passage is the bleed passage, and the suction pressure zone
includes a first pressure zone and a second pressure zone, wherein
the pressure of the first pressure zone is higher than the pressure
of the second pressure zone, and wherein the first chamber is
connected to one of the first and second pressure zones, and the
second chamber and the valve hole are connected to the other one of
the first and second pressure zones.
13. The refrigerant circuit according to claim 12, wherein a
restrictor is provided in the suction pressure zone, and wherein a
section of the suction pressure zone that is upstream of the
restrictor comprises the first pressure zone, and a section of the
suction pressure zone that is downstream of the restrictor
comprises the second pressure zone.
14. The refrigerant circuit according to claim 9, wherein the
compressor has a compressor housing in which an accommodation
recess is formed, wherein the control valve is inserted in the
accommodation recess, and wherein the second chamber and the valve
hole are connected to each other through a space defined between an
inner surface of the accommodation recess and an outer surface of
the valve housing.
15. The refrigerant circuit according to claim 9, wherein a
connecting passage for connecting the second chamber to the valve
hole is formed in the valve housing.
16. The refrigerant circuit according to claim 9, wherein the
control valve has an actuator, and wherein, based on an external
command, the actuator changes a force applied to the valve body.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a displacement varying
structure of a variable displacement compressor. A typical variable
displacement compressor is installed in a refrigerant circuit of a
vehicle air conditioning system and changes the displacement based
on the pressure in a crank chamber. A displacement varying
structure controls the pressure in the crank chamber of the
variable displacement compressor.
[0002] Some variable displacement compressor have a control valve
called pressure sensing valve (for example, refer to Japanese
Laid-Open Patent Publication No. 2001-173556).
[0003] As shown in FIG. 6, a supply passage 113 connects a crank
chamber 111 with a discharge chamber 112 of a variable displacement
compressor. A valve chamber 102, which forms part of the supply
passage 113, is defined in a housing 101 of the control valve. The
valve chamber 102 is connected to the crank chamber 111 by a
downstream section of the supply passage 113. The valve chamber 102
accommodates a valve body portion 103a of a rod 103. The valve body
portion 103a can be displaced in the valve chamber 102. In
accordance with its position in the valve chamber 102, the valve
body portion 103a adjusts the opening degree of the supply passage
113.
[0004] A pressure sensing chamber 104 is defined in the valve
housing 101. A pressure sensing member 105, which is a bellows, is
located in the pressure sensing chamber 104. The pressure sensing
member 105 divides the interior of the pressure sensing chamber 104
into a first chamber 104a and a second chamber 104b.
[0005] A separation wall 106 is provided in the valve housing 101.
The separation wall 106 separates the second chamber 104b from the
valve chamber 102. A through hole 107 is formed in the separation
wall 106. The through hole 107 extends between the valve chamber
102 and the second chamber 104b. The rod 103 extends through the
through hole 107 and is coupled to the pressure sensing member
105.
[0006] The rod 103 has a separation portion 103b that is provided
at the end adjacent to the pressure sensing chamber 104. The
separation portion 103b disconnects the valve chamber 102 from the
second chamber 104b. The rod 103 also has a coupler portion 103c,
that couples the separation portion 103b with the valve body
portion 103a. The diameter of the coupler portion 103c is less than
the diameter of the through hole 107. Therefore, this section of
the through hole 107 functions as a valve hole 107a that forms part
of the supply passage 113.
[0007] A fixed restrictor 114 is in the refrigerant circuit.
Specifically, the fixed restrictor 114 is located in a discharge
pressure zone. The first chamber 104a of the control valve is
connected to the discharge pressure zone at a position upstream of
the fixed restrictor 114. The second chamber 104b of the control
valve is connected to the discharge pressure zone at a position
downstream of the fixed restrictor 114. The pressure difference
between a section upstream of the fixed restrictor 114 and a
section downstream of the fixed restrictor 114 represents the flow
rate of refrigerant in the refrigerant circuit. Therefore, the
pressure sensing member 105 is displaced according to changes of
the refrigerant flow rate in the refrigerant circuit. The position
of the rod 103 (the valve body portion 103a) is determined such
that the displacement of the variable displacement compressor is
changed to cancel the changes in the refrigerant flow rate.
[0008] However, the valve hole 107a of the control valve is
connected to the discharge pressure zone (discharge chamber 112) of
the refrigerant circuit at a position upstream of the fixed
restrictor 114 through an upstream section of the supply passage
113. That is, the valve hole 107a is connected to a section of the
discharge pressure zone that is the same as the first chamber 104a
and different from the second chamber 104b.
[0009] Therefore, the pressures in the valve hole 107a and the
second chamber 104b, which are adjacent to each other with the
separation portion 103b of the rod 103 in between, are different.
This pressure difference can cause foreign particles to enter the
sliding sections of the through hole 107 and the rod 103 (the
separation portion 103b). Foreign particles between the through
hole 107 and the rod 103 can cause the rod 103 to malfunction.
[0010] To eliminate such a drawback, Japanese Laid-Open Patent
Publication No. 2001-173556 discloses another structure shown in
FIG. 7 that is different from the structure shown in FIG. 6. In the
control valve shown in FIG. 7, the rod 103 has no structure
corresponding to the separation portion 103b. Further, the second
chamber 104b is used as part of the supply passage 113. The space
between the through hole 107 and the rod 103 (the coupler portion
103c) functions as part of the supply passage 113 and is always
open to the second chamber 104b. However, in this case, at the
instant at which the valve body portion 103a is displaced to change
the valve opening degree, the pressure in the second chamber 104b
is directly influenced by the change in the valve opening degree
and is changed. This prevents the pressure sensing member 105 from
accurately determining the position of the valve body portion 103a,
which adversely affects the control of the displacement.
[0011] Particularly, the compressor shown in FIG. 7 is a "variable
target pressure difference" type, in which position of the rod 103
(the valve body portion 103a) is determined by the equilibrium of
the force of the pressure sensing member 105 and electromagnetic
force of an electromagnetic actuator (not shown). This worsens the
controllability of the displacement of the compressor shown in FIG.
7. Specifically, the electromagnetic force of the electromagnetic
actuator is sometimes changed abruptly by an excessive degree. In
such a case, the valve body portion 103a is displaced abruptly by
an excessive degree. This creates a sudden and excessive change in
the pressure in the second chamber 104b.
SUMMARY OF THE INVENTION
[0012] Accordingly, it is an objective of the present invention to
provide a displacement varying structure of a variable displacement
compressor, which structure prevents a rod from malfunctioning and
the controllability of the displacement from deteriorating.
[0013] To achieve the above objective, the present invention
provides a displacement varying structure of a variable
displacement compressor. The compressor is installed in a
refrigerant circuit. The refrigerant circuit has a discharge
pressure zone and a suction pressure zone. The variable
displacement compressor has a crank chamber The displacement
varying structure is capable of varying a displacement of the
variable displacement compressor by changing a pressure of the
crank chamber. The displacement varying structure includes a supply
passage for connecting the crank chamber with the discharge
pressure zone. A bleed passage connects the crank chamber with the
suction pressure zone. A control valve is located in a control
passage. The control passage is one of the supply passage and the
bleed passage. The control valve includes a valve housing defining
a valve chamber, a valve hole, and a pressure sensing chamber. The
valve chamber and the valve hole form a part of the control
passage. A valve body is accommodated in the valve chamber. The
valve body is capable of being displaced. The valve body adjusts an
opening degree of the valve hole in accordance with the position of
the valve body in the valve chamber. A pressure sensing member is
accommodated in the pressure sensing chamber. The pressure sensing
member divides the pressure sensing chamber into a first chamber
and a second chamber. The pressure sensing member is capable of
being displaced in accordance with a pressure difference between
the first chamber and the second chamber. A separation wall
separates in the valve housing the valve chamber and the pressure
sensing chamber from each other. The separation wall has a through
hole for connecting the valve chamber and the second chamber with
each other. A rod extends through the through hole and connects the
pressure sensing member and the vale body with each other. The rod
has a separation portion that blocks connection between the valve
chamber and the second chamber through the through hole. An
adjacent zone is adjacent to the second chamber with the separation
portion in between. If a part of the through hole that is closer to
the valve chamber than the separation portion and opens to the
valve chamber forms the valve hole, the valve hole is the adjacent
zone. If the valve hole is located at the opposite side of the
valve chamber with respect to the second chamber, the valve chamber
is the adjacent zone. The adjacent zone and the second chamber are
connected to a common pressure zone in the refrigerant circuit.
[0014] 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
[0015] 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:
[0016] FIG. 1 is a cross-sectional view illustrating a swash plate
type variable displacement compressor according to one embodiment
of the present invention;
[0017] FIG. 2 is a cross-sectional view illustrating the control
valve installed in the compressor shown in FIG. 1;
[0018] FIG. 3 is a partial cross-sectional view illustrating a
control valve according to a second embodiment of the present
invention;
[0019] FIG. 4 is a partial cross-sectional view illustrating a
control valve according to a third embodiment of the present
invention;
[0020] FIG. 5 is a cross-sectional view illustrating a control
valve according to a fourth embodiment of the present
invention;
[0021] FIG. 6 is a partial cross-sectional view illustrating a
prior art control valve; and
[0022] FIG. 7 is a partial cross-sectional view illustrating
another prior art control valve.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] First to fourth embodiments of a displacement control
structure used in a variable displacement swash plate type
compressor C will now be described. The compressor is installed in
a refrigerant circuit of a vehicle air conditioner. In the second
to fourth embodiments, only the parts different from the first
embodiment are explained. Like members are given the like numbers
and detailed explanations are omitted. The first embodiment will
now be described.
Variable Displacement Swash Plate Type Compressor
[0024] As shown in FIG. 1, the compressor C has a housing. The
compressor housing includes a cylinder block 11, a front housing
member 12, a valve assembly 13, and a rear housing member 14. The
front housing member 12 is secured to the front end (left end as
viewed in FIG. 1) of the cylinder block 11. The rear housing member
14 is secured to the rear end (right end as viewed in FIG. 1) of
the cylinder block 11 with the valve assembly 13 in between.
[0025] The cylinder block 11 and the front housing member 12 define
a crank chamber 15 in between. A drive shaft 16 is rotatably
supported in the crank chamber 15. The drive shaft 16 is coupled to
a vehicle engine E, which functions as an external drive source. A
lug plate 17 is coupled to the drive shaft 16 and is located in the
crank chamber 15. The lug plate 17 rotates integrally with the
drive shaft 16.
[0026] A cam plate, which is a swash plate 18 in the first
embodiment, is housed in the crank chamber 15. The swash plate 18
slides along and inclines with respect to the drive shaft 16. A
hinge mechanism 19 is located between the lug plate 17 and the
swash plate 18. The hinge mechanism 19 causes the swash plate 18
rotate integrally with the lug plate 17 and the drive shaft 16, and
permits the swash plate 18 to incline with respect to the drive
shaft 16, while sliding on the drive shaft 16 along the axis of the
drive shaft 16. The inclination angle of the swash plate 18 is
represented by an angle formed by the swash plate 18 and a plane
perpendicular to the axis of the drive shaft 16.
[0027] Cylinder bores 11a (only one is shown in the drawing) are
formed in the cylinder block 11 to surround the drive shaft 16.
Each cylinder bore 11a extends through the cylinder block 11 along
the axis of the drive shaft 16. A single headed piston 20 is
accommodated in each cylinder bore 11a. The piston 20 reciprocates
inside the cylinder bore 11a. The openings of each cylinder bore
11a are closed by the valve assembly 13 and the corresponding
piston 20. A compression chamber 21 is defined inside each cylinder
bore 11a. The volume of each compression chamber 21 changes as the
corresponding piston 20 reciprocates. Each piston 20 is coupled to
the peripheral portion of the swash plate 18 by a pair of shoes 22.
The shoes 22 convert rotation of the swash plate 18, which rotates
with the drive shaft 16, to reciprocation of the pistons 20.
[0028] A suction chamber 23 and a discharge chamber 24 are defined
between the valve assembly 13 and the rear housing member 14. The
valve assembly 13 has suction ports 25, suction valve flaps 26,
discharge ports 27, and discharge valve flaps 28. Each suction port
25, each suction valve flap 26, each discharge port 27, and each
discharge valve flap 28 correspond to one of the cylinder bores
11a. As each piston 20 moves from the top dead center to the bottom
dead center, refrigerant gas in the suction chamber 23 is drawn
into the corresponding compression chamber 21 through the
corresponding suction port 25 while flexing the suction valve flap
26 to an open position. Refrigerant gas that is drawn into the
compression chamber 21 is compressed to a predetermined pressure as
the piston 20 is moved from the bottom dead center to the top dead
center. Then, the gas is discharged to the discharge chamber 24
through the corresponding discharge port 27 while flexing the
discharge valve flap 28 to an open position.
Displacement Varying Structure
[0029] The pressure of the crank chamber 15 contributes to control
of the inclination angle of the swash plate 18 and is controlled by
a displacement varying structure. The displacement varying
structure includes a bleed passage 29, a supply passage 30, and a
control valve CV1, which are provided in the compressor housing
shown in FIG. 1. The bleed passage 29 connects the crank chamber 15
with the suction chamber 23, which forms part of a suction pressure
zone of the refrigerant circuit. The supply passage 30 connects a
discharge pressure zone Pd of the refrigerant circuit with the
crank chamber 15. The supply passage 30 is regulated by the control
valve CV1. The control valve CV1 is inserted in and fixed to an
accommodation recess 35 formed in the rear housing member 14.
[0030] Adjusting the opening degree of the control valve CV1
controls the ratio between the flow rate of highly pressurized gas
supplied to the crank chamber 15 from the discharge pressure zone
Pd through the supply passage 30 and the flow rate of refrigerant
gas conducted from the crank chamber 15 to the suction chamber 23
through the bleed passage 29. The pressure of the crank chamber 15
is determined, accordingly. The difference between the pressure in
the crank chamber 15 and the pressure in the compression chambers
21 with the pistons 20 in between is changed according to changes
in the pressure of the crank chamber 15. This alters the
inclination angle of the swash plate 18. As a result, the stroke of
each piston 20, that is, the displacement of the compressor C, is
controlled.
Refrigerant Circuit
[0031] As shown in FIG. 1, the refrigerant circuit of the vehicle
air conditioner includes the compressor C and an external
refrigerant circuit G. The external refrigerant circuit G includes
a condenser (gas cooler) 31, an expansion valve 32, and an
evaporator 33. A section of the refrigerant circuit from the
discharge chamber 24 to the inlet of the condenser 31 form the
discharge pressure zone Pd.
[0032] A fixed restrictor 34 is provided in the discharge pressure
zone Pd. As the flow rate of refrigerant in the refrigerant circuit
increases, the pressure difference between a section upstream of
the fixed restrictor 34 and a section downstream of the fixed
restrictor 34 is increased. This pressure difference will be
referred to as a two-point pressure difference. That is, the
two-point pressure difference corresponds to the pressure loss
between the section upstream of the fixed restrictor 34 and the
section downstream of the fixed restrictor 34, and positively
correlates with the flow rate in the refrigerant circuit.
Therefore, detecting the two-point pressure difference permits the
flow rate of the refrigerant circuit to be indirectly detected.
[0033] The discharge pressure zone Pd of the refrigerant circuit
includes a first pressure zone PdH and a second pressure zone PdL.
The first pressure zone PdH is located upstream of the fixed
restrictor 34, or at the side corresponding to the discharge
chamber 24. The second pressure zone PdL is located downstream of
the fixed restrictor 34, or at the side corresponding to the
condenser 31. The pressure of the first pressure zone PdH is higher
than the pressure of the second pressure zone PdL. The pressure of
the first pressure zone PdH and the pressure of the second pressure
zone PdL are each introduced to the control valve CV1. The supply
passage 30 includes an upstream section 30a upstream of the
accommodation recess 35 and a downstream section 30b downstream of
the accommodation recess 35. The upstream section 30a is connected
to the second pressure zone PdL.
Control Valve
[0034] As shown in FIG. 2, the control valve CV1 includes an inlet
valve portion and a solenoid 60. The inlet valve portion is
arranged in an upper portion of the valve CV1, while the solenoid
60 is arranged in a lower portion of the valve CV1. The inlet valve
portion adjusts the opening degree (throttle amount) of the supply
passage 30. The solenoid 60 is an electromagnetic actuator for
urging a rod 40 located in the control valve CV1 based on a current
supplied from an outside source. The rod 40 includes a separation
portion 41, a coupler portion 42, a valve body portion 43, and a
guide portion 44. The separation portion 41 is at the distal end of
the rod 40. The diameter of the coupler portion 42 is less than
that of the separation portion 41. The valve body portion 43 is
located at a middle portion of the rod 40. The guide portion 44 is
located at the proximal end of the rod 40. The valve body portion
43 forms part of the guide portion 44.
[0035] The control valve CV1 has a valve housing 45. The housing 45
includes a plug 45a and an upper portion 45b and a lower portion
45c. The upper portion 45b defines the shape of the inlet valve
portion. The lower portion 45c defines the shape of the solenoid
60. A valve chamber 46 is defined in the upper portion 45b of the
valve housing 45. A pressure sensing chamber 48 is defined between
the upper portion 45b and the plug 45a, which is press fitted to
the top portion of the upper portion 45b. The upper portion 45b
includes a separation wall 49 located between the valve chamber 46
and the pressure sensing chamber 48. A through hole 47 is formed in
the separation wall 49. The through hole 47 extends between the
valve chamber 46 and the pressure sensing chamber 48.
[0036] The rod 40 extends through the valve chamber 46 and the
through hole 47. The rod 40 moves in the axial direction of the
control valve CV1, or in the vertical direction as viewed in FIG.
2. The separation portion 41 of the rod 40 is slidably inserted in
the through hole 47 and separates the through hole 47 from the
pressure sensing chamber 48. The diameter of the coupler portion 42
of the rod 40 is less than that of the through hole 47 and permits
the valve chamber 46 to communicate with the through hole 47.
[0037] A space 50 is defined between an outer surface 45d of the
upper portion 45b and an inner surface 35a of the accommodation
recess 35 of the rear housing member 14. The space 50 is divided
into a first connecting chamber 50a and a second connecting chamber
50b by a first seal member 68 provided about the upper portion 45b.
The second connecting chamber 50b is closer to the opening of the
accommodation recess 35 than the first connecting chamber 50a. That
is, the second connecting chamber 50b is located below the first
connecting chamber 50a as viewed in FIG. 2. The second connecting
chamber 50b is disconnected from the outside air by a second seal
member 69 provided about the lower portion 45c.
[0038] The bottom of the valve chamber 46 is formed by the upper
surface of a fixed iron core 62. A radially extending first port 51
is formed in the wall surrounding the valve chamber 46 of the upper
portion 45b. The first port 51 connects the second connecting
chamber 50b with the valve chamber 46. Therefore, the valve chamber
46 is connected to the crank chamber 15 through the first port 51,
the second connecting chamber 50b, and the downstream section 30b
of the supply passage 30.
[0039] A radially extending second port 52 is formed in the
separation wall 49 surrounding the through hole 47 of the upper
portion 45b. The second port 52 connects the first connecting
chamber 50a with a portion 47a of the through hole 47 that is close
to the valve chamber 46. Therefore, the portion 47a of the through
hole 47 closer to the valve chamber 46 is connected to the second
pressure zone PdL through the second port 52, the first connecting
chamber 50a, and the upstream section 30a of the supply passage
30.
[0040] That is, the first port 51, the valve chamber 46, the
through hole 47, and the second port 52 function as an internal
passage of the control valve CV1 and as part of the supply passage
30 connecting the second pressure zone PdL and the crank chamber
15.
[0041] The valve body portion 43 of the rod 40 is located in the
valve chamber 46. A step defined between the valve chamber 46 and
the through hole 47 forms a valve seat 53. A portion 47a of the
through hole 47 adjacent to the valve chamber 46 functions as a
valve hole. The rod 40 shown in FIG. 2 is located at the lowermost
position. When the rod 40 is moved from the lowermost position to
the uppermost position, where the valve body portion 43 contacts
the valve seat 53, the valve hole 47a is closed. The valve body
portion 43 of the rod 40 is an inlet valve body that controls the
opening degree of the supply passage 30.
[0042] A pressure sensing member 54, which is a bellows, is located
in the pressure sensing chamber 48. The upper end of the pressure
sensing member 54 is fixed to the plug 45a of the valve housing 45.
The pressure sensing member 54 is shaped as a cylinder with a
closed end. The pressure sensing member 54 divides the pressure
sensing chamber 48 into a first chamber 55, which is the interior
of the pressure sensing member 54, and a second chamber 56, which
is the exterior of the pressure sensing member 54. The second
chamber 56 is located closer to the valve chamber 46 compared to
the first chamber 55 and is connected to the valve chamber 46 by
the through hole 47. The second chamber 56 is adjacent to the valve
hole 47a with the separation portion 41 of the rod 40 in between.
The lower end of the pressure sensing member 54 is displaced in
accordance with the pressure difference between the first chamber
55 and the second chamber 56. A recess is formed at the lower end
of the pressure sensing member 54. The recess functions as a rod
receiving portion 54a. The separation portion 41 of the rod 40 is
inserted in and press fitted to the rod receiving portion 54a.
[0043] The first chamber 55 is connected to the discharge chamber
24 through a third port 57 formed in the plug 45a, and a pressure
introduction passage 37 formed in the rear housing member 14. The
discharge chamber 24 forms a part of the first pressure zone PdH. A
fourth port 58 is formed in a circumferential wall of the upper
portion 45b of the valve housing 45 that surrounds the first
chamber 55. The second chamber 56 is connected to the second
pressure zone PdL through the fourth port 58, the first connecting
chamber 50a, and the upstream section 30a of the supply passage 30.
Therefore, the pressure difference between the first chamber 55 and
the second chamber 56 is equal to the two-point pressure difference
in the refrigerant circuit, which is the pressure difference
between the first pressure zone PdH and the second pressure zone
PdL.
[0044] The first connecting chamber 50a connects the second port 52
with the fourth port 58. That is, the passage from the second
pressure zone PdL to the control valve CV1 branches at the first
connecting chamber 50a. The branched portions are connected to the
second chamber 56 and the valve hole 47a. In other words, part of
the passage connecting the second chamber 56 to the second pressure
zone PdL and part of the passage connecting the valve hole 47a to
the second pressure zone PdL both include the upstream section 30a
of the supply passage 30 and the first connecting chamber 50a.
[0045] That is, if one of the valve hole 47a and the valve chamber
46 that is adjacent to the second chamber 56 with the separation
portion 41 in between is defined as an adjacent zone, the adjacent
zone is the valve hole 47a in this embodiment. The second chamber
56 and the valve hole 47a are both connected to a common pressure
zone in the refrigerant circuit, or to the second pressure zone
PdL.
[0046] The solenoid 60 includes an accommodation cylinder 61 that
has a closed end. The fixed iron core 62 is fitted to the upper
portion of the accommodation cylinder 61. Accordingly, a solenoid
chamber 63 is defined in a lower portion of the accommodation
cylinder 61. A movable iron core 64 is located in the solenoid
chamber 63. The movable iron core 64 is movable along the axial
direction of the control valve CV1. A guide hole 62a is formed in
the center of the fixed iron core 62. The guide hole 62a extends
along the axial direction of the control valve CV1. The guide
portion 44 of the rod 40 is received by the guide hole 62a. The
guide portion 44 is movable in the axial direction of the control
valve CV1. The lower end of the guide portion 44 abuts against the
movable iron core 64 in the solenoid chamber 63.
[0047] A valve body urging spring 66 is accommodated in the
solenoid chamber 63. The valve body urging spring 66 urges the
movable iron core 64 toward the fixed iron core 62, thereby urging
the rod 40 (the valve body portion 43) upward as viewed in the
drawing. Therefore, the movable iron core 64 and the rod 40
integrally move vertically.
[0048] A coil 67 is wound about the fixed iron core 62 and the
movable iron core 64. The coil 67 receives drive signals based on
commands that are sent from an air conditioner ECU (not shown)
according to parameters such as thermal load. The coil 67 generates
an electromagnetic attraction force (electromagnetic urging force)
between the movable iron core 64 and the fixed iron core 62. The
magnitude of the generated force corresponds to the value of the
supplied current per unit time.
[0049] A target value sought in a control of the two-point pressure
difference, or a target pressure difference as an operation
reference, is determined by the amount of current supplied to the
coil 67. The pressure sensing member 54 automatically determines
the axial position of the rod 40 (the valve body portion 43)
according to the two-point pressure difference such that the target
pressure difference is maintained.
[0050] For example, if the flow rate of the refrigerant in the
refrigerant circuit is decreased due to a decrease in the rotation
speed of the engine E, that is, if the two-point pressure
difference is decreased from the target pressure difference, the
downward force applied to the rod 40 by the pressure sensing member
54 based on the two-point pressure difference decreases. If the
upward electromagnetic force of the solenoid 60 is not changed from
the value at the time, the upward and downward forces acting on the
rod 40 are not balanced. Thus, the rod 40 (the valve body portion
43) moves upward to decrease the opening degree of the valve hole
47a, which lowers the pressure in the crank chamber 15.
Accordingly, the inclination angle of the swash plate 18 is
increased, and the displacement of the compressor C is increased.
The increase in the displacement of the compressor C increases the
flow rate of refrigerant in the refrigerant circuit. This increases
the two-point pressure difference in the refrigerant circuit so
that the pressure difference seeks the target pressure
difference.
[0051] If the flow rate of the refrigerant in the refrigerant
circuit is increased due to an increase in the rotation speed of
the engine E, that is, if the two-point pressure difference is
increased from the target pressure difference, the downward force
applied to the rod 40 by the pressure sensing member 54 based on
the two-point pressure difference increases. If the upward
electromagnetic force of the solenoid 60 is not changed from the
value at the time, the upward and downward forces acting on the rod
40 are not balanced. Thus, the rod 40 (the valve body portion 43)
moves downward to increase the opening degree of the valve hole
47a, which raises the pressure in the crank chamber 15.
Accordingly, the inclination angle of the swash plate 18 is
decreased, and the displacement of the compressor C is decreased.
The decrease in the displacement of the compressor C decreases the
flow rate of refrigerant in the refrigerant circuit. This decreases
the two-point pressure difference in the refrigerant circuit so
that the pressure difference seeks the target pressure
difference.
[0052] The target pressure difference can be externally changed by
adjusting the amount of electricity supplied to the coil 67. For
example, if the amount of electricity supplied to the coil 67 is
increased, the upward electromagnetic force applied to the rod 40
by the solenoid 60 is increased. In this case, if the force of the
pressure sensing member 54 based on the two-point pressure
difference is not changed, the upward force and the downward force
acting on the rod 40 are not balanced. Accordingly, the rod 40 (the
valve body portion 43) is moved upward to decrease the opening
degree of the valve hole 47a, and the displacement of the
compressor C is increased. As a result, the flow rate of
refrigerant in the refrigerant circuit increases. This increases
the two-point pressure difference in the refrigerant circuit. That
is, increasing the amount of electricity supplied to the coil 67
increases the target pressure difference.
[0053] If the amount of electricity supplied to the coil 67 is
decreased, the upward electromagnetic force applied to the rod 40
by the solenoid 60 is decreased. In this case, if the force of the
pressure sensing member 54 based on the two-point pressure
difference is not changed, the upward force and the downward force
acting on the rod 40 are not balanced. Accordingly, the rod 40 (the
valve body portion 43) is moved downward to increase the opening
degree of the valve hole 47a, and the displacement of the
compressor C is decreased. As a result, the flow rate of
refrigerant in the refrigerant circuit decreases. This decreases
the two-point pressure difference in the refrigerant circuit. That
is, decreasing the amount of electricity supplied to the coil 67
decreases the target pressure difference.
[0054] The present embodiment has the following advantages.
[0055] (1) In the control valve CV1, the separation portion 41 of
the rod 40 disconnects the valve chamber 46 from the second chamber
56 through the through hole 47. Therefore, the pressure of the
second chamber 56 is not directly affected by changes in the
opening degree of the valve body portion 43. This prevents the
pressure in the second chamber 56 from being fluctuated by changes
in the valve opening degree. Thus, the pressure sensing member 54
accurately determines the position of the rod 40 (the valve body
portion 43) without being affected by changes in the valve opening
degree. Accordingly, the pressure displacement is accurately
controlled.
[0056] The second chamber 56 of the control valve CV1 and the valve
hole 47a, which is adjacent to the second chamber 56 with the
separation portion 41 in between, are both connected to the second
pressure zone PdL. This configuration prevents the pressure of the
valve hole 47a and the pressure of the second chamber 56 from
differing from each other. Therefore, the entry of foreign
particles to the sliding portions of the through hole 47 and the
rod 40 (the separation portion 41) due to the pressure difference
between the valve hole 47a and the second chamber 56 is prevented.
The rod 40 is therefore prevented from malfunctioning due to
foreign particles.
[0057] As described above, this embodiment prevents the rod 40 from
malfunctioning and also prevents the controllability of the
compressor displacement from deteriorating.
[0058] (2) The fixed restrictor 34 is provided in the discharge
pressure zone Pd. The section upstream of the fixed restrictor 34
is the first pressure zone PdH, and the section downstream of the
fixed restrictor 34 is the second pressure zone PdL. The two-point
pressure difference, which is the pressure difference between the
section upstream of the fixed restrictor 34 and the section
downstream of the fixed restrictor 34, is greater than a pressure
difference caused by the passage resistance in a passage having no
restrictor. Therefore, the control valve CV1, which operates by
detecting the two-point pressure difference, accurately reflects
changes in the refrigerant flow rate when determining the position
of the rod 40 (the valve body portion 43). The control valve CV1
thus accurately controls the displacement of the compressor C.
[0059] Although the pressure in the section upstream of the fixed
restrictor 34 and the pressure in the section downstream of the
fixed restrictor 34 are pressures in the discharge pressure zone
Pd, these two pressures upstream and downstream of the restrictor
34 are greatly different from each other in some cases. Therefore,
connecting the second chamber 56 and the valve hole 47a, which are
adjacent to each other with the separation portion 41 in between,
to the second pressure zone PdL, or to the section downstream of
the fixed restrictor 34, is particularly advantageous to provide
the above advantage (prevention of malfunction of the rod 40).
[0060] (3) The valve housing 45 of the control valve CV1 is
inserted in the accommodation recess 35 formed in the rear housing
member 14. The second chamber 56 is connected to the valve hole 47a
through the first connecting chamber 50a, which is a space defined
between the inner surface 35a of the accommodation recess 35 and
the outer surface 45d of the valve housing 45. Therefore, only one
passage is required for connecting the second pressure zone PdL
with the first connecting chamber 50a. Thus, for example, compared
to a case in which the second chamber 56 and the valve hole 47a are
each connected to the second pressure zone PdL through an
independent passage, respectively, the structure is simplified.
[0061] The first connecting chamber 50a has a relatively large
volume. This lessens the influences of pressure fluctuations caused
by changes in the valve opening degree of the valve hole 47a to the
second chamber 56. Further, the second chamber 56 is connected to
the valve hole 47a through the first connecting chamber 50a located
outside of the valve housing 45. This structure extends the length
of the passage between the second chamber 56 and the valve hole
47a. This configuration reliably prevents the pressure of the
second chamber 56 from being directly influenced by changes in the
valve opening degree.
[0062] (4) The control valve CV1 has the solenoid 60, which is an
electromagnetic actuator. As stated in the prior art section, in a
control valve having an electromagnetic actuator, adopting a
structure that completely opens the entire through hole 47 as a
part of the supply passage 30 worsens the controllability of the
displacement. Thus, in the control valve CV1 having the solenoid
60, blocking the connection between the valve chamber 46 and the
second chamber 56 through the through hole 47 with the separation
portion 41 of the rod 40 is particularly advantageous to improve
the controllability of the displacement.
[0063] A second embodiment of the present invention will now be
described. As shown in FIG. 3, a control valve CV2 of the second
embodiment is the same as the control valve CV1 of the first
embodiment except for that the fourth port 58 is omitted. The
second chamber 56 is connected to the second port 52 through a hole
71 formed in the separation wall 49. Therefore, the pressure of the
second pressure zone PdL is introduced to the second chamber 56
through the second port 52 and the hole 71. That is, the second
port 52 and the hole 71 form a connecting passage. The connecting
passage (the second port 52 and the hole 71) connects the second
chamber 56 with the valve hole 47a within the valve housing 45.
[0064] The second embodiment provides the same advantages as (1),
(2) and (4) of the first embodiment. Other than these advantages,
the second embodiment has the following advantages. That is, the
second chamber 56 and the valve hole 47a are connected to each
other within the valve housing 45 through the connecting passage
(the second port 52 and the hole 71). Thus, only one passage, which
is connected to the valve hole 47a, is required for connecting the
second pressure zone PdL to the control valve CV2. Thus, for
example, compared to a case in which the second chamber 56 and the
valve hole 47a are each connected to the second pressure zone PdL
through an independent passage, respectively, the structure is
simplified.
[0065] For example, compared to the first embodiment, in which the
second chamber 56 and the valve hole 47a are connected to each
other through the space defined by the inner surface 35a of the
accommodation recess 35 and the outer surface 45d of the valve
housing 45, that is the first connecting chamber 50a, no great
space needs to be created between the inner surface 35a of the
accommodation recess 35 and the outer surface 45d of the valve
housing 45. Therefore, the inner surface 35a of the accommodation
recess 35 are brought into close contact with the outer surface 45d
of the valve housing 45 in a relatively large area. This permits
the rear housing member 14 of the compressor C to stably support
the control valve CV2.
[0066] A third embodiment of the present invention will now be
described. As shown in FIG. 4, a control valve CV3 of the third
embodiment is the same as the control valve CV1 of the first
embodiment except for that the opening degree of the bleed passage
29, not the opening degree of the supply passage 30, is adjusted.
The supply passage 30 is always open. The control valve CV3 adjusts
the opening degree of the bleed passage 29, thereby changing the
flow rate of refrigerant gas conducted to the suction chamber 23
from the crank chamber 15 through the bleed passage 29. As a
result, the pressure of the crank chamber 15 is adjusted, and the
displacement of the compressor C is controlled, accordingly.
[0067] Unlike the control valve CV1 of the first embodiment, the
first chamber 55 and the second chamber 56 forming the pressure
sensing chamber 48 of the control valve CV3 according to the third
embodiment are connected to a suction pressure zone Ps of the
refrigerant circuit.
[0068] A section of the refrigerant circuit from the outlet of the
evaporator 33 to the suction chamber 23 of the compressor forms the
suction pressure zone Ps. A fixed restrictor 91 is provided in the
suction pressure zone Ps. The suction pressure zone Ps includes a
first pressure zone PsH and a second pressure zone PsL. The first
pressure zone PsH is located upstream of the fixed restrictor 91,
or at the side corresponding to the evaporator 33. The second
pressure zone PsL is located downstream of the fixed restrictor 91,
or at the side corresponding to the suction chamber 23. The
pressure of the first pressure zone PsH is higher than the pressure
of the second pressure zone PsL. The pressure of the first pressure
zone PsH is introduced to the first chamber 55 through a pressure
introduction passage 92 formed in the rear housing member 14 and
the third port 57. The bleed passage 29 includes an upstream
section 29a upstream of the accommodation recess 35 and a
downstream section 29b downstream of the accommodation recess 35.
The suction chamber 23 forms a part of the second pressure zone
PsL. The pressure of the suction chamber 23 is introduced to the
second chamber 56 through the downstream section 29b, the first
connecting chamber 50a, and the fourth port 58.
[0069] An inner connecting chamber 94 and a valve accommodating
hole 95 are defined in the upper portion 45b of the control valve
CV3. The valve accommodating hole 95 functions as a valve chamber
and a through hole. The inner connecting chamber 94 and the valve
accommodating hole 95 are connected to each other by a connecting
passage 96 that has a smaller cross-sectional area than the valve
accommodating hole 95. The rod 40 is movably provided in the inner
connecting chamber 94, the connecting passage 96, and the valve
accommodating hole 95. The separation portion 41 of the rod 40 is
slidably inserted in the valve accommodating hole 95 and separates
the valve accommodating hole 95 from the pressure sensing chamber
48. The diameter of the coupler portion 42 of the rod 40 is less
than that of the connecting passage 96 and permits the inner
connecting chamber 94 to communicate with the valve accommodating
hole 95.
[0070] In this embodiment, the valve body portion 43 forms part of
the separation portion 41. The valve body portion 43 is located in
the valve accommodating hole 95. A step defined between the valve
accommodating hole 95 and the connecting passage 96 forms the valve
seat 53. The connecting passage 96 functions as a valve hole.
[0071] The inner connecting chamber 94 is connected to the crank
chamber 15 through the first port 51, the second connecting chamber
50b, and the upstream section 29a of the bleed passage 29. Part of
the valve accommodating hole 95 that is closer to the inner
connecting chamber 94 will be referred to a valve body
accommodating portion 95a. The valve body accommodating portion 95a
is adjacent to second chamber 56 with the separation portion 41 in
between. The valve body accommodating portion 95a is connected to
the suction chamber 23 through the second port 52, the first
connecting chamber 50a, and the downstream section 29b of the bleed
passage 29. That is, the second chamber 56 and the valve body
accommodating portion 95a of the valve accommodating hole 95 are
both connected to a common pressure zone in the refrigerant
circuit, or to the second pressure zone PsL.
[0072] As the flow rate of refrigerant in the refrigerant circuit
increases, the difference between a section upstream of the fixed
restrictor 91 and a section downstream of the fixed restrictor 91,
or the two-point pressure difference, is increased. That is, the
two-point pressure difference corresponds to the pressure loss
between the section upstream of the fixed restrictor 91 and the
section downstream of the fixed restrictor 34, and positively
correlates with the flow rate in the refrigerant circuit.
Therefore, the control valve CV3 of this embodiment operates in the
same manner as the control valve CV1 of the first embodiment. That
is, the control valve CV3 adjusts the opening degree of the bleed
passage 29 such that the displacement of the compressor is changed
to cancel fluctuations of the refrigerant flow rate.
[0073] The third embodiment provides the same advantages as (1) to
(4) of the first embodiment.
[0074] A fourth embodiment of the present invention will now be
described. As shown in FIG. 5, a control valve CV4 of the fourth
embodiment is the same as the control valve CV1 of the first
embodiment except for that the solenoid 60 is omitted. Further, the
control valve CV4 controls the opening degree of the bleed passage
29, but not the opening degree of the supply passage 30.
[0075] That is, in the fourth embodiment, the valve chamber 46 is a
part of the bleed passage 29 that is located in the control valve
CV4. The valve chamber 46 accommodates a valve body 75 attached to
the rod 40. The valve body 75 can be displaced in the valve chamber
46. The pressure sensing member 54 and the valve body 75 are
coupled to each other with the rod 40. A valve hole 76, which forms
part of the bleed passage 29, is spaced apart from the through hole
47. Specifically, the valve hole 76 is connected to the valve
chamber 46 at a part opposite from the part corresponding to the
through hole 47 with respect to the valve body 75.
[0076] The second chamber 56 of the control valve CV4 is connected
to the suction chamber 23 through a port 80 formed in the valve
housing 45, and a pressure introducing passage 77 formed in the
rear housing member 14. The first chamber 55 is either exposed to
the atmosphere or is in a vacuum. That is, the internal pressure of
the first chamber 55 is maintained to a substantially constant
reference pressure. The valve chamber 46 is connected to the
suction chamber 23 through a port 81 formed in the valve housing
45, and the downstream section 29b of the bleed passage 29. The
valve hole 76 is connected to the crank chamber 15 through a port
82 formed in the valve housing 45, and the upstream section 29a of
the bleed passage 29. That is, the second chamber 56 and the valve
chamber 46, which are adjacent to each other with the separation
portion 41 of the rod 40 in between, are both exposed to the
pressure of the suction chamber 23, which forms part of the suction
pressure zone.
[0077] In other words, in the fourth embodiment, the valve chamber
46 is the adjacent zone, which is adjacent to the second chamber 56
with the separation portion 41 in between. The second chamber 56
and the valve hole 47a are both connected to a common pressure zone
in the refrigerant circuit, or to the suction chamber 23.
[0078] The downstream section 29b of the bleed passage 29 and the
pressure introducing passage 77 may be separately formed or have a
common section. As in the first embodiment, the space 50 may be
defined between the outer surface 45d of the valve housing 45 and
the inner surface of the accommodation recess 35, and the valve
chamber 46 may be connected to the second chamber 56 through the
space 50 (see FIG. 2). Alternatively, as in the second embodiment,
the hole 71 may be formed in the separation wall 49, and the valve
chamber 46 and the second chamber 56 may be connected to each other
through the hole 71 within the valve housing 45 (see FIG. 3).
[0079] In the compressor of fourth embodiment, highly pressurized
discharge refrigerant gas is supplied from the discharge chamber 24
to the crank chamber 15 through the supply passage 30. On the other
hand, to maintain the pressure of the suction chamber 23 at a
constant level, the pressure sensing member 54 of the control valve
CV4 is displaced in accordance with the difference between the
pressure of the suction chamber 23, which is introduced to the
second chamber 56 through the pressure introducing passage 77, and
the reference pressure in the first chamber 55 to determine the
axial position of the valve body 75. Accordingly, the opening
degree of the valve hole 76 is adjusted. The control valve CV4
adjusts the opening degree of the bleed passage 29, thereby
changing the flow rate of refrigerant gas conducted to the suction
chamber 23 from the crank chamber 15 through the bleed passage 29.
As a result, the pressure of the crank chamber 15 is adjusted, and
the displacement of the compressor C is controlled,
accordingly.
[0080] For example, when the temperature of the passenger
compartment increases, the cooling load increases. This increases
the pressure in the suction chamber 23. Accordingly, the pressure
difference between the second chamber 56 and the first chamber 55
in the control valve CV4 is increased. Therefore, the pressure
sensing member 54 is displaced downward as viewed in the drawing
against the reference pressure of the first chamber 55 and the
force of the urging spring 78, which is located in the pressure
sensing member 54 and urges the valve body 75 toward the valve seat
53 through the rod 40. Accordingly, the valve body 75 is displaced
to increase the valve opening, and the pressure in the crank
chamber 15 is lowered. Accordingly the displacement of the
compressor C is increased. The increase in the compressor
displacement lowers the suction pressure in the suction chamber
23.
[0081] When the temperature of the passenger compartment decreases,
the cooling load decreases. This decreases the suction pressure in
the suction chamber 23. Accordingly, the pressure difference
between the second chamber 56 and the first chamber 55 in the
control valve CV4 is decreased. Therefore, the pressure sensing
member 54 is displaced upward as viewed in the drawing by the
reference pressure of the first chamber 55 and the force of the
urging spring 78. Accordingly, the valve body 75 is displaced to
decrease the valve opening, and the pressure in the crank chamber
15 is raised. Accordingly the displacement of the compressor C is
decreased. The decrease in the compressor displacement raises the
suction pressure in the suction chamber 23.
[0082] The fourth embodiment provides the same advantage as (1) of
the first embodiment.
[0083] The present invention may be embodied in the following forms
without departing from the spirit or scope of the invention.
[0084] In the first to third embodiments, the solenoid 60 may be
omitted from the control valves CV1 to CV3 so that the control
valves CV1 to CV3 are simple pressure sensing valves that are not
capable of being externally controlled.
[0085] In the fourth embodiment, a solenoid may be added to the
control valve CV4, so that the control valve CV4 is a pressure
sensing valve that is capable of being externally controlled. In
this case, the pressure sensing member 54 of the control valve CV4
is automatically displaced according to fluctuations in the suction
pressure to determine the axial position of the valve body 75, such
that a target value of the suction pressure, which is determined by
the amount of electricity supplied to the solenoid, is maintained.
That is, the pressure sensing member 54 is displaced such that the
target suction pressure as the operation reference is maintained.
The target suction pressure can be externally changed by adjusting
the amount of electricity supplied to the solenoid.
[0086] In the control valves CV1 and CV2 of the first and second
embodiments, the first chamber 55 is exposed to the pressure of the
first pressure zone PdH, which is a higher pressure section of the
discharge pressure zone Pd, and the second chamber 56 and the valve
hole 47a are each exposed to the pressure of the second pressure
zone PdL, which is a lower pressure section of the discharge
pressure zone Pd. In the control valve CV3 of the third embodiment,
the first chamber 55 is exposed to the pressure of the first
pressure zone PsH, which is a higher pressure section of the
suction pressure zone Ps, and the second chamber 56 and the valve
body accommodating portion 95a, which is a valve chamber, are each
exposed to the pressure of the second pressure zone PsL, which is a
lower pressure section of the suction pressure zone Ps. That is, in
the first to third embodiments, the pressure of the first chamber
55 is higher than those of the second chamber 56 and the adjacent
zone (the valve hole 47a and the valve body accommodating portion
95a). However, the pressure of the first chamber 55 may be lower
than those of the second chamber and the adjacent zone. That is,
the first chamber 55 of the control valves may be exposed to the
pressure of the second pressure zone, and the second chamber 56 and
the adjacent zone may be exposed to the pressure of the first
pressure zone.
[0087] In the control valves CV1 to CV3 of the first to third
embodiments, setting the pressure of the first chamber higher than
the pressure of the second chamber reverses the direction of
displacement of the pressure sensing member 54 based on the
pressure difference between the first chamber 55 and the second
chamber 56. Therefore, in the modifications of the first and second
embodiments, the arrangement of the valve hole and the valve
chamber with respect to the pressure sensing chamber 48 needs to be
inverted so that an increase in the pressure difference between the
first and second chambers 55, 56 displaces the valve body portion
43 to increase the valve opening degree. That is, the second
chamber 56 and the valve chamber 46 are arranged to be adjacent to
each other with the separation portion 41 in between. In the
modification of the third embodiment, the arrangement of the valve
hole and the valve chamber with respect to the pressure sensing
chamber 48 needs to be inverted so that an increase in the pressure
difference between the first and second chambers 55, 56 displaces
the valve body to decrease the valve opening degree. That is, the
second chamber 56 and the valve hole are arranged to be adjacent to
each other with the separation portion 41 in between.
[0088] 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 and equivalence of the appended claims.
* * * * *