Information
-
Patent Grant
-
6682314
-
Patent Number
6,682,314
-
Date Filed
Tuesday, January 22, 200222 years ago
-
Date Issued
Tuesday, January 27, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Tyler; Cheryl J.
- Liu; Han L
Agents
-
CPC
-
US Classifications
Field of Search
US
- 417 2222
- 417 53
- 417 269
- 417 2221
- 251 615
- 251 12902
- 251 12907
- 251 12908
- 251 12915
- 062 2281
- 062 2285
-
International Classifications
-
Abstract
A control valve has a valve housing and a valve chamber defined in the valve housing. A valve body is accommodated in the valve chamber for adjusting the opening degree of a supply passage. A pressure sensing chamber is defined in the valve housing. The pressure at a pressure monitoring point in a refrigerant circuit is applied to the pressure sensing chamber. A bellows is located in the pressure sensing chamber. The bellows has a movable end. A transmission rod is slidably supported by the valve housing. The transmission rod includes the valve body. A support spring is located between the inner wall of the pressure sensing chamber and the movable end of the bellows. The spring supports the movable end such that the movable end can be displaced. The movable end of the bellows includes a protrusion such that the spring and the movable end of the bellows are fitted to each other.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a control valve for a variable displacement compressor that is used in a refrigerant circuit of a vehicle air conditioner and changes the displacement in accordance with the pressure in a crank chamber.
The control valve includes, for example, a valve body, a bellows, and a transmission rod. The opening degree of the valve body is controlled in accordance with the pressure in a crank chamber. The movable end of the bellows is displaced in accordance with the pressure in a suction pressure zone of the refrigerant circuit. The transmission rod couples the valve body to the movable end of the bellows so that the valve body integrally moves with the movable end of the bellows. When the movable end of the bellows is displaced in accordance with the pressure in the suction pressure zone, the valve body moves by means of the transmission rod. The discharge displacement of the compressor is adjusted to cancel the variations of the pressure in the suction pressure zone in accordance with the position of the valve body.
If the movable end of the bellows simply contacts the transmission rod, a measurement error in the bellows during manufacturing may incline the axis of the bellows with respect to the axis of the valve housing. If the inclination of the bellows is great, the bellows contacts the inner wall of a sensing chamber, in which the bellows is accommodated. As a result, the fluctuations of pressure in the suction pressure zone are not reliably communicated to the valve body. That is, the control valve malfunctions.
To reduce the malfunction of the control valve, the following art has been proposed. That is, a recess is formed on the movable end of the bellows. The end of the transmission rod is fitted to the recess. The bellows is supported by a valve housing through the transmission rod. Therefore, the inclination of the bellows caused by a measurement error is corrected. However, due to the correction of the inclination, the elastic bellows generates stress in a direction that intersects the axis of the valve housing. The stress is applied to the transmission rod through the fitted portion. Therefore, the friction between the transmission rod and the valve housing increases due to the stress. As a result, the hysteresis in the operational characteristics of the control valve increases.
SUMMARY OF THE INVENTION
The objective of the present invention is to provide a control valve for a variable displacement compressor that suppresses the inclination of a bellows and prevents the transmission rod from being affected by forces applied by the bellows in a direction that intersects the axial direction.
To achieve the foregoing objective, the present invention provides a control valve used for a variable displacement compressor installed in a refrigerant circuit. The compressor varies the displacement in accordance with the pressure in a crank chamber. The compressor has a control passage, which connects the crank chamber to a pressure zone in which the pressure is different from the pressure of the crank chamber. The control valve includes a valve housing, a valve chamber, a valve body, a pressure sensing chamber, a bellows, a transmission rod, and an elastic member. The valve chamber is defined in the valve housing. The valve body is accommodated in the valve chamber for adjusting the opening degree of the control passage. The pressure sensing chamber is defined in the valve housing. The pressure at a pressure monitoring point in the refrigerant circuit is applied to the pressure sensing chamber. The bellows is located in the pressure sensing chamber. The bellows has a movable end. The transmission rod is slidably supported by the valve housing between the valve chamber and the pressure sensing chamber. The transmission rod moves the valve body in accordance with the displacement of the bellows. The bellows is displaced in accordance with the variations of the pressure in the pressure sensing chamber thereby moving the valve body such that the displacement of the compressor is adjusted to cancel the variations of the pressure in the pressure sensing chamber. The movable end of the bellows and the transmission rod contact each other and can be relatively displaced in a direction intersecting the axis of the valve housing. The elastic member is located between the inner wall of the pressure sensing chamber and the movable end of the bellows. The elastic member elastically supports the movable end such that the movable end can be displaced. One of the elastic member and the movable end of the bellows includes a recess and the other one includes a protrusion such that the elastic member and the movable end of the bellows are fitted to each other.
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
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:
FIG. 1
is a cross-sectional view illustrating a swash plate type variable displacement compressor according to a first embodiment of the present invention;
FIG. 2
is a cross-sectional view illustrating the control valve provided in the compressor shown in
FIG. 1
;
FIG. 2A
is an enlarged partial cross-sectional view illustrating the vicinity of the movable end of the bellows shown in
FIG. 2
;
FIG. 3
is an enlarged partial cross-sectional view illustrating a control valve according to a second embodiment of the present invention;
FIG. 4
is an enlarged partial cross-sectional view illustrating a control valve according to a third embodiment of the present invention;
FIG. 5
is an enlarged partial cross-sectional view illustrating a control valve according to a fourth embodiment of the present invention; and
FIG. 6
is an enlarged partial cross-sectional view illustrating a control valve according to a fifth embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A control valve CV according to a first embodiment of the present invention will now be described with reference to
FIGS. 1 and 2
. The control valve CV is used in a variable displacement swash plate type compressor located in a vehicle air conditioner.
As shown in
FIG. 1
, the compressor includes a cylinder block
1
, a front housing member
2
connected to the front end of the cylinder block
1
, and a rear housing member
4
connected to the rear end of the cylinder block
1
. A valve plate assembly
3
is located between the rear housing member
4
and the cylinder block
1
. The cylinder block
1
, the front housing member
2
, and the rear housing member
4
form the housing of the compressor.
A crank chamber
5
, in this embodiment, is defined between the cylinder block
1
and the front housing member
2
. A drive shaft
6
extends through the crank chamber
5
and is rotatably supported. The drive shaft
6
is connected to and driven by an external drive source, which is an engine E in this embodiment.
A lug plate
11
is fixed to the drive shaft
6
in the crank chamber
5
to rotate integrally with the drive shaft
6
. A drive plate, which is a swash plate
12
in this embodiment, is accommodated in the crank chamber
5
. The swash plate
12
slides along the drive shaft
6
and inclines with respect to the axis of the drive shaft
6
. A hinge mechanism
13
is provided between the lug plate
11
and the swash plate
12
. The hinge mechanism
13
and the lug plate
11
cause the swash plate
12
to move integrally with the drive shaft
6
.
Cylinder bores
1
a
(only one is shown in
FIG. 1
) are formed in the cylinder block
1
at constant angular intervals around the axis L of the drive shaft
6
. Each cylinder bore
1
a
accommodates a single headed piston
20
such that the piston
20
can reciprocate in the cylinder bore
1
a.
The opening of each cylinder bore
1
a
is closed by the valve plate assembly
3
and the corresponding piston
20
. A compression chamber, the volume of which varies in accordance with the reciprocation of the piston
20
, is defined in each cylinder bore
1
a.
The front end of each piston
20
is coupled to the periphery of the swash plate
12
through a pair of shoes
19
. The swash plate
12
is rotated as the drive shaft
6
rotates. Rotation of the swash plate
12
is converted into reciprocation of each piston
20
by the corresponding pair of shoes
19
.
A suction chamber
21
and a discharge chamber
22
are defined between the valve plate assembly
3
and the rear housing member
4
. The discharge chamber
22
is located about the suction chamber
21
. The valve plate assembly
3
has suction ports
23
, suction valve flaps
24
, discharge ports
25
, and discharge valve flaps
26
. Each set of the suction port
23
, the suction valve flap
24
, the discharge port
25
, and the discharge valve flap
26
corresponds to one of the cylinder bores
1
a.
When each piston
20
moves from the top dead center position to the bottom dead center position, refrigerant gas in the suction chamber
21
flows into the corresponding cylinder bore
1
a
via the corresponding suction port
23
and suction valve flap
24
. When each piston
20
moves from the bottom dead center position to the top dead center position, refrigerant gas in the corresponding cylinder bore
1
a
is compressed to a predetermined pressure and is discharged to the discharge chamber
22
via the corresponding discharge port
25
and discharge valve flap
26
.
A mechanism for controlling the pressure in the crank chamber
5
, or crank chamber pressure Pc, includes a bleed passage
27
, a supply passage
28
, and the control valve CV. The passages
27
,
28
are formed in the housing. The bleed passage
27
connects a zone that is exposed to a suction pressure Ps (suction pressure zone), or the suction chamber
21
, with the crank chamber
5
. The supply passage
28
connects a zone that is exposed to a discharge pressure Pd (discharge pressure zone), or the discharge chamber
22
, with the crank chamber
5
. The control valve CV is located in the supply passage
28
.
The control valve CV adjusts the opening of the supply passage
28
to adjust the flow rate of refrigerant gas from the discharge chamber
22
to the crank chamber
5
. The crank chamber pressure Pc is changed in accordance with the relationship between the flow rate of refrigerant gas flowing from the discharge chamber
22
to the crank chamber
5
and the flow rate of refrigerant gas flowing out from the crank chamber
5
to the suction chamber
21
through the bleed passage
27
. The difference between the crank chamber pressure Pc and the pressure in the cylinder bores
1
a
through the piston
20
is changed in accordance with the crank chamber pressure Pc, which varies the inclination angle of the swash plate
12
. This alters the stroke of each piston
20
and the compressor displacement.
The refrigerant circuit of the vehicular air-conditioner is made up of the compressor and an external refrigerant circuit
30
. The external refrigerant circuit
30
connects the discharge chamber
22
to the suction chamber
21
, and includes a condenser
31
, an expansion valve
32
, and an evaporator
33
. A downstream pipe
35
is located in a downstream portion of the external refrigerant circuit
30
. The downstream pipe
35
connects the outlet of the evaporator
33
with the suction chamber
21
of the compressor. An upstream pipe
36
is located in the upstream portion of the external refrigerant circuit
30
. The upstream pipe
36
connects the discharge chamber
22
of the compressor with the inlet of the condenser
31
.
The greater the flow rate of the refrigerant flowing in the refrigerant circuit is, the greater the pressure loss per unit length of the circuit or piping is. That is, the pressure loss (pressure difference) between pressure monitoring points P
1
, P
2
has a positive correlation with the flow rate of the refrigerant in the circuit. Detecting the pressure difference between the pressure monitoring points P
1
, P
2
permits the flow rate of refrigerant in the refrigerant circuit to be indirectly detected. Hereinafter, the pressure difference between the pressure monitoring points P
1
, P
2
will be referred to as pressure difference ΔPd.
As shown in
FIG. 2
, the first pressure monitoring point P
1
is located in the discharge chamber
22
, the pressure of which is equal to that of the most upstream section of the upstream pipe
36
. The second pressure monitoring point P
2
is set midway along the upstream pipe
36
at a position separated from the first pressure monitoring point P
1
by a predetermined distance. The pressure PdH at the first pressure monitoring point P
1
is applied to the displacement control valve CV through a first pressure introduction passage
37
. The pressure PdL at the second pressure monitoring point P
2
is applied to the displacement control valve CV through a second pressure introduction passage
38
.
The control valve CV has a supply control valve portion
59
and a solenoid
60
. The supply control valve portion
59
controls the opening (throttle amount) of the supply passage
28
, which connects the discharge chamber
22
with the crank chamber
5
. The solenoid
60
serves as an electromagnetic actuator for controlling a transmission rod
40
located in the control valve CV on the basis of an externally supplied electric current. Specifically, the solenoid
60
applies force to a bellows
54
, which will be described later, through the transmission rod
40
on the basis of an externally supplied electric current. The transmission rod
40
includes a distal end portion
41
, a coupler
42
, a valve body portion
43
, and a guide portion
44
. The valve body portion
43
is located at the substantial center of the transmission rod
40
and is a part of the guide portion
44
.
A valve housing
45
of the control valve CV has a plug
45
a,
an upper half body
45
b,
and a lower half body
45
c.
A valve chamber
46
and a communication passage
47
are defined in the upper half body
45
b.
A pressure sensing chamber
48
is defined between the upper half body
45
b
and the plug
45
a.
The transmission rod
40
moves in the axial direction L of the valve housing
45
in the valve chamber
46
and the communication passage
47
. The valve chamber
46
is selectively connected to and disconnected from the communication passage
47
in accordance with the axial position of the transmission rod
40
. The communication passage
47
is isolated from the pressure sensing chamber
48
by the distal end portion
41
of the transmission rod
40
, which is fitted to the communication passage
47
.
The upper end face of a stationary iron core
62
, which will be discussed below, serves as the bottom wall of the valve chamber
46
. A first valve port
51
, extending radially from the valve chamber
46
, connects the valve chamber
46
with the discharge chamber
22
through an upstream part of the supply passage
28
. A second valve port
52
, extending radially from the communication passage
47
, connects the communication passage
47
with the crank chamber
5
through a downstream part of the supply passage
28
. Thus, the first valve port
51
, the valve chamber
46
, the communication passage
47
, and the second valve port
52
serve as part of the control passage, or the supply passage
28
, which connects the discharge chamber
22
with the crank chamber
5
.
The valve body portion
43
of the transmission rod
40
is located in the valve chamber
46
. The step between the valve chamber
46
and the communication passage
47
functions as a valve seat
53
. When the transmission rod
40
moves from the position of
FIG. 2
(the lowest position) to the highest position, at which the valve body portion
43
contacts the valve seat
53
, the communication passage
47
is isolated. That is, the valve body portion
43
functions as a valve body that selectively opens and closes the supply passage
28
.
A bottomed cylindrical bellows
54
is located in the pressure sensing chamber
48
. The bellows
54
is formed of metal material. The bellows
54
is preferably made of alloy mainly made of copper. A fixed end
54
b
at the upper end of the bellows
54
is fixed to the plug
45
a
of the valve housing
45
by, for example, welding. The pressure sensing chamber
48
is divided into a first pressure chamber
55
and a second pressure chamber
56
by the bellows
54
.
As shown in
FIG. 2A
, a protrusion
68
is formed on a movable end
54
a,
which is the lower end of the bellows
54
, and faces the transmission rod
40
. The bellows
54
is installed in a compressed state. Therefore, a lower end surface
68
a
of the protrusion
68
is pressed against an upper end surface
41
a
of the distal end portion
41
by the downward force generated by the compression of the bellows
54
. The movable end
54
a,
or the bellows
54
, and the distal end portion
41
, or the transmission rod
40
, are relatively displaced in a direction intersecting the axis L of the valve housing
45
.
An elastic member, which is a support spring
69
formed of a coil spring in the first embodiment, is arranged between the inner bottom surface of the pressure sensing chamber
48
and the movable end
54
a
of the bellows
54
. The proximal end of the support spring
69
is fitted to a spring seat
48
a,
which is formed on the inner bottom surface of the pressure sensing chamber
48
. The distal end of the support spring
69
is fitted to the movable end
54
a
through a circumferential surface
68
b
of the protrusion
68
. The center space in the support spring
69
serves as a recess
69
a,
in which the protrusion
68
of the movable end
54
a
is fitted. As mentioned above, the movable end
54
a
of the bellows
54
is elastically supported by the valve housing
45
through the support spring
69
and the spring seat
48
a
to be displaced in the direction of axis L.
The first pressure chamber
55
is connected to the first pressure monitoring point P
1
, which is the discharge chamber
22
, through a P
1
port
57
formed in the plug
45
a,
and the first pressure introduction passage
37
. The second pressure chamber
56
is connected to the second pressure monitoring point P
2
through a P
2
port
58
, which is formed in the upper half body
45
b
of the valve housing
45
, and the second pressure introduction passage
38
. Therefore, the first pressure chamber
55
is exposed to the pressure PdH monitored at the first pressure monitoring point P
1
, and the second pressure chamber
56
is exposed to the pressure PdL monitored at the second pressure monitoring point P
2
.
The solenoid
60
includes an accommodating cup
61
. The stationary iron core
62
is fitted in the upper part of the accommodating cup
61
. A solenoid chamber
63
is defined in the accommodating cup
61
. A movable iron core
64
is accommodated in the solenoid chamber
63
to move along the axis of the valve housing
45
. An axially extending guide hole
65
is formed in the central portion of the stationary iron core
62
. The guide portion
44
of the transmission rod
40
is located to move axially in the guide hole
65
. The lower end of the guide portion
44
is fixed to the movable iron core
64
in the solenoid chamber
63
. Accordingly, the movable iron core
64
moves vertically and integrally with the transmission rod
40
.
In the solenoid chamber
63
, a coil spring
66
is located between the stationary iron core
62
and the movable iron core
64
. The spring
66
urges the movable iron core
64
away from the stationary iron core
62
and urges the transmission rod
40
, or the valve body portion
43
, downward as viewed in the drawing.
A coil
67
is wound about the stationary iron core
62
and the movable iron core
64
. The coil
67
is connected to a drive circuit
71
, and the drive circuit
71
is connected to a controller
70
. The controller
70
is connected to an external information detector
72
. The controller
70
receives external information (on-off state of the air conditioner, the temperature of the passenger compartment, and a target temperature) from the detector
72
. Based on the received information, the controller
70
commands the drive circuit
71
to supply a drive signal to the coil
67
. The coil
67
generates an electromagnetic force, the magnitude of which depends on the value of the supplied current, between the stationary iron core
62
and the movable iron core
64
. The value of the current supplied to the coil
67
is controlled by controlling the voltage applied to the coil
67
. In this embodiment, the voltage applied to the coil
67
is duty controlled.
The opening degree of the control valve CV is determined by the position of the transmission rod
40
.
As shown in
FIG. 2
, when no current is supplied to the coil
67
(duty ratio=0%), the downward force of the bellows
54
and the spring
66
is dominant in determining the position of the transmission rod
40
. As a result, the transmission rod
40
is moved to its lowermost position shown in FIG.
2
and causes the valve body portion
43
to fully open the communication passage
47
. Accordingly, the crank chamber pressure Pc is maximized. Therefore, the difference between the crank chamber pressure Pc and the pressure in the cylinder bores la through the piston
20
is increased, which minimizes the inclination angle of the swash plate
12
and the compressor displacement.
When the electric current corresponding to the minimum duty ratio (duty ratio>0%) within the range of duty ratios is supplied to the coil
67
, the upward electromagnetic force exceeds the downward force of the bellows
54
and the spring
66
, and the transmission rod
40
moves upward. In this state, the resultant of the upward electromagnetic force and the downward force of the spring
66
acts against the resultant of the forces of the bellows
54
and the force based on the pressure difference between the pressure monitoring points P
1
, P
2
(ΔPd=PdH−PdL) and the upward force of support spring
69
. The position of the valve body portion
43
of the transmission rod
40
relative to the valve seat
53
is determined such that upward and downward forces are balanced.
When the speed of the engine E is lowered, the flow rate of refrigerant in the refrigerant circuit is decreased. At this time, the downward force based on the pressure difference ΔPd is decreased and the transmission rod
40
(the valve body portion
43
) moves upward, which decreases the opening of the communication passage
47
. Accordingly, the crank chamber pressure Pc is decreased, and the difference between the crank chamber pressure Pc and the pressure in each cylinder bore
1
a
decreases. Thus, the inclination angle of the swash plate
12
increases, which increases the discharge displacement of the compressor. When the discharge displacement of the compressor increases, the flow rate of refrigerant in the refrigerant circuit increases, which increases the pressure difference ΔPd.
When the speed of the engine E is increased, the flow rate of refrigerant in the refrigerant circuit is increased. At this time, the downward force based on the pressure difference ΔPd is increased and the transmission rod
40
(the valve body portion
43
) moves downward, which increases the opening of the communication passage
47
. Accordingly, the crank chamber pressure Pc is increased and the difference between the crank chamber pressure Pc and the pressure in each cylinder bore
1
a
increases. Thus, the inclination angle of the swash plate
12
decreases, which decreases the discharge displacement of the compressor. When the discharge displacement of the compressor decreases, the flow rate of refrigerant in the refrigerant circuit decreases, which decreases the pressure difference ΔPd.
If the duty ratio to the coil
67
is increased to increase the upward electromagnetic force, the transmission rod
40
moves upward and the opening degree of the communication passage
47
is decreased. As a result, the compressor displacement is increased, and the pressure difference ΔPd is increased.
If the duty ratio to the coil
67
is decreased to decrease the upward electromagnetic force, the transmission rod
40
moves downward and the opening degree of the communication passage
47
is increased. As a result, the compressor displacement is decreased, and the pressure difference ΔPd is decreased.
As described above, the target value of the pressure difference ΔPd is determined by the duty ratio supplied to the coil
67
. The control valve CV automatically determines the position of the transmission rod
40
according to changes of the pressure difference ΔPd to maintain the pressure difference ΔPd to the target value. The target value of the pressure difference ΔPd is changed by adjusting the duty ratio to the coil
67
.
The embodiment of
FIGS. 1 and 2
has the following advantages.
The movable end
54
a
of the bellows
54
contacts the transmission rod
40
and relatively moves in a direction that intersects the axis L of the valve housing
45
. Therefore, the transmission rod
40
is prevented from being affected by the stress of the bellows
54
, which tends to elastically incline because of tolerances in a direction that intersects the axis L. Also the increase of the friction between the transmission rod
40
and the valve housing
45
caused by the stress is avoided. Thus, the hysteresis in the operational characteristics of the control valve CV is reduced.
The movable end
54
a
of the bellows
54
is supported by the valve housing
45
through the support spring
69
, which is fitted to the movable end
54
a.
Therefore, the inclination of the bellows
54
is corrected by the valve housing
45
through the support spring
69
.
The support spring
69
is located outside the protrusion
68
. Therefore, it is easy to apply a relatively large diameter coil spring for the support spring
69
. Thus, the flexibility of design is improved.
The coil spring is used as the support spring
69
. Since the coil spring has a center space, the space in the coil spring is used as the recess
69
a.
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.
FIG. 3
illustrates a second embodiment of the present invention. The second embodiment is a modification of the first embodiment. In the second embodiment, a recess
81
is formed on the movable end
54
a
of the bellows
54
and the distal end portion of the support spring
69
is fitted to the recess
81
. In this case, the recess
81
is formed in the internal space of the bellows
54
. Thus, the size of the control valve CV is minimized along the axis L. An inner end surface
81
a
of the recess
81
contacts an upper end surface
41
a
of the distal end portion
41
.
FIG. 4
illustrates a third embodiment of the present invention. The third embodiment is a modification of the first embodiment. In the third embodiment, the lower end surface
68
a
of the protrusion
68
is semispherical. In this case, the force corresponding to the displacement of the bellows
54
is reliably applied to the transmission rod
40
along the axis L even when the bellows
54
is inclined. Therefore, the control valve CV operates in a suitable manner. The upper end surface
41
a
of the distal end portion
41
may be semispherical.
FIG. 5
illustrates a fourth embodiment of the present invention. The fourth embodiment is a modification of the first embodiment. In the fourth embodiment, the support spring
69
is a conic coil spring. Since the conic coil spring is tough against the bending load, the inclination of the bellows
54
is more reliably corrected.
A disk spring may be used as the support spring
69
.
A rubber may be used as the elastic member.
FIG. 6
illustrates a fifth embodiment of the present invention. The fifth embodiment is a modification of the first embodiment. In the fifth embodiment, the first pressure monitoring point P
1
is located in the suction pressure zone, which includes the evaporator
33
and the suction chamber
21
. Specifically, the first pressure monitoring point P
1
is located in the downstream pipe
35
. The second pressure monitoring point P
2
is also located in the suction pressure zone and downstream of the first pressure monitoring point P
1
. Specifically, the second pressure monitoring point P
2
is located in the suction chamber
21
.
The first pressure monitoring point P
1
may be located in the discharge pressure zone, which includes the discharge chamber
22
and the condenser
31
, and the second pressure monitoring point P
2
may be located in the suction pressure zone, which includes the evaporator
33
and the suction chamber
21
.
The communication passage
47
may be connected to the discharge chamber
22
through the second valve port
52
of the control valve CV and the upstream part of the supply passage
28
, and the valve chamber
46
may be connected to the crank chamber
5
through the first valve port
51
of the control valve CV and the downstream part of the supply passage
28
.
The solenoid
60
, which is externally controlled, may be eliminated from the control valve CV and the control valve CV may be an internal control valve.
The pressure sensing member of the control valve CV may be operated in accordance with one of the suction pressure Ps, the crank chamber pressure Pc, or the discharge pressure Pd. For example, only one pressure monitoring point P
1
may be provided in the embodiments illustrated in
FIGS. 1
to
6
and the second pressure chamber
56
may be exposed to the atmosphere (constant pressure) or may be vacuumed.
The control valve CV may be used as a bleed control valve for controlling the crank chamber pressure Pc by controlling the opening of the bleed passage
27
instead of the supply passage
28
.
The present invention may be embodied in a control valve of a wobble type variable displacement compressor.
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.
Claims
- 1. A control valve used for a variable displacement compressor installed in a refrigerant circuit, wherein the compressor varies the displacement in accordance with the pressure in a crank chamber, wherein the compressor has a control passage, which connects the crank chamber to a pressure zone in which the pressure is different from the pressure of the crank chamber, the control valve comprising:a valve housing; a valve chamber defined in the valve housing; a valve body, which is accommodated in the valve chamber for adjusting the opening degree of the control passage; a pressure sensing chamber defined in the valve housing, wherein the pressure at a pressure monitoring point in the refrigerant circuit is applied to the pressure sensing chamber; a bellows, which is located in the pressure sensing chamber, wherein the bellows has a movable end; a transmission rod slidably supported by the valve housing between the valve chamber and the pressure sensing chamber, wherein the transmission rod moves the valve body in accordance with the displacement of the bellows, wherein the bellows is displaced in accordance with the variations of the pressure in the pressure sensing chamber thereby moving the valve body such that the displacement of the compressor is adjusted to cancel the variations of the pressure in the pressure sensing chamber, and wherein the movable end of the bellows and the transmission rod contact each other and can be relatively displaced in a direction intersecting the axis of the valve housing; and an elastic member located between the inner wall of the pressure sensing chamber and the movable end of the bellows, wherein the elastic member elastically supports the movable end such that the movable end can be displaced, and wherein one of the elastic member and the movable end of the bellows includes a recess and the other one includes a protrusion such that the elastic member and the movable end of the bellows are fitted to each other.
- 2. The control valve according to claim 1, wherein the recess is arranged on the elastic member, and the protrusion is arranged on the movable end of the bellows.
- 3. The control valve according to claim 1, wherein the protrusion is arranged on the elastic member, and the recess is arranged on the movable end of the bellows.
- 4. The control valve according to claim 1, wherein the elastic member is a coil spring.
- 5. The control valve according to claim 4, wherein the coil spring is conic.
- 6. The control valve according to claim 1, wherein the protrusion is semispherical.
- 7. The control valve according to claim 1, wherein the bellows define a first pressure chamber and a second pressure chamber in the pressure sensing chamber, and wherein the pressure at a first pressure monitoring point in the refrigerant circuit is applied to the first pressure chamber, and the pressure at a second pressure monitoring point, which is downstream of the first pressure monitoring point, is applied to the second pressure chamber.
- 8. The control valve according to claim 7, wherein the bellows is displaced in accordance with the variations of the pressure difference between the first pressure chamber and the second pressure chamber.
- 9. The control valve according to claim 7, wherein the refrigerant circuit has a discharge pressure zone, and wherein the first and the second pressure monitoring points are located in the discharge pressure zone.
- 10. The control valve according to claim 7, wherein the refrigerant circuit has a suction pressure zone, and wherein the first and the second pressure monitoring points are located in the suction pressure zone.
- 11. The control valve according to claim 7 further comprising an actuator for applying force to the bellows in accordance with an externally supplied electric current, wherein the force applied by the actuator reflects the target value of the pressure difference between the first pressure chamber and the second pressure chamber, and wherein the bellows moves the valve body such that the pressure difference seeks to the target value.
- 12. A control valve used for a variable displacement compressor installed in a refrigerant circuit, wherein the compressor varies the displacement in accordance with the pressure in a crank chamber, wherein the compressor has a control passage, which connects the crank chamber to a pressure zone in which the pressure is different from the pressure of the crank chamber, the control valve comprising:a valve housing; a valve chamber defined in the valve housing; a valve body, which is accommodated in the valve chamber for adjusting the opening degree of the control passage; a pressure sensing chamber defined in the valve housing, wherein the pressure at a pressure monitoring point in the refrigerant circuit is applied to the pressure sensing chamber; a bellows, which is located in the pressure sensing chamber, wherein the bellows has a movable end; a transmission rod slidably supported by the valve housing between the valve chamber and the pressure sensing chamber, wherein the transmission rod includes the valve body, and the bellows is displaced in accordance with the variations of the pressure in the pressure sensing chamber thereby moving the valve body such that the displacement of the compressor is adjusted to cancel the variations of the pressure in the pressure sensing chamber, and wherein the movable end of the bellows and the transmission rod contact each other and can be relatively displaced in a direction intersecting the axis of the valve housing; and an elastic member located between the inner wall of the pressure sensing chamber and the movable end of the bellows, wherein the elastic member directly contacts the inner wall of the pressure sensing chamber and the movable end of the bellows wherein the elastic member elastically supports the movable end such that the movable end can be displaced, and wherein the movable end of the bellows includes a protrusion and the elastic member includes a recess such that the elastic member and the movable end of the bellows are fitted to each other.
- 13. The control valve according to claim 12, wherein the elastic member is a coil spring.
- 14. The control valve according to claim 13, wherein the coil spring is conic.
- 15. The control valve according to claim 12, wherein the protrusion is semispherical.
- 16. The control valve according to claim 12, wherein the bellows define a first pressure chamber and a second pressure chamber in the pressure sensing chamber, and wherein the pressure at a first pressure monitoring point in the refrigerant circuit is applied to the first pressure chamber, and the pressure at a second pressure monitoring point, which is downstream of the first pressure monitoring point, is applied to the second pressure chamber.
- 17. The control valve according to claim 16, wherein the bellows is displaced in accordance with the variations of the pressure difference between the first pressure chamber and the second pressure chamber.
- 18. The control valve according to claim 16, wherein the refrigerant circuit has a discharge pressure zone, and wherein the first and the second pressure monitoring points are located in the discharge pressure zone.
- 19. The control valve according to claim 16, wherein the refrigerant circuit has a suction pressure zone, and wherein the first and the second pressure monitoring points are located in the suction pressure zone.
- 20. The control valve according to claim 16 further comprising an actuator for applying force to the bellows in accordance with an externally supplied electric current, wherein the force applied by the actuator reflects the target value of the pressure difference between the first pressure chamber and the second pressure chamber, and wherein the bellows moves the valve body such that the pressure difference seeks to the target value.
- 21. A control valve used for a variable displacement compressor installed in a refrigerant circuit, wherein the compressor varies the displacement in accordance with the pressure in a crank chamber, wherein the compressor has a control passage, which connects the crank chamber to a pressure zone in which the pressure is different from the pressure of the crank chamber, the control valve comprising:a valve housing; a valve chamber defined in the valve housing; a valve body, which is accommodated in the valve chamber for adjusting the opening degree of the control passage; a pressure sensing chamber defined in the valve housing, wherein the pressure at a pressure monitoring point in the refrigerant circuit is applied to the pressure sensing chamber; a bellows, which is located in the pressure sensing chamber, wherein the bellows has a movable end, wherein the bellows define a first pressure chamber and a second pressure chamber in the pressure sensing chamber, and wherein the pressure at a first pressure monitoring point in the refrigerant circuit is applied to the first pressure chamber, and the pressure at a second pressure monitoring point, which is downstream of the first pressure monitoring point, is applied to the second pressure chamber; a transmission rod slidably supported by the valve housing between the valve chamber and the pressure sensing chamber, wherein the transmission rod moves the valve body in accordance with the displacement of the bellows, wherein the bellows is displaced in accordance with the variations of the pressure in the pressure sensing chamber thereby moving the valve body such that the displacement of the compressor is adjusted to cancel the variations of the pressure in the pressure sensing chamber, and wherein the movable end of the bellows and the transmission rod contact each other and can be relatively displaced in a direction intersecting the axis of the valve housing; and an elastic member located between the inner wall of the pressure sensing chamber and the movable end of the bellows, wherein the elastic member elastically supports the movable end such that the movable end can be displaced, and wherein one of the elastic member and the movable end of the bellows includes a recess and the other one includes a protrusion such that the elastic member and the movable end of the bellows are fitted to each other.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2001-014615 |
Jan 2001 |
JP |
|
US Referenced Citations (7)
Number |
Name |
Date |
Kind |
6010312 |
Suitou et al. |
Jan 2000 |
A |
6146106 |
Suitou et al. |
Nov 2000 |
A |
6179572 |
Taguchi |
Jan 2001 |
B1 |
6217291 |
Ota et al. |
Apr 2001 |
B1 |
6234763 |
Ota et al. |
May 2001 |
B1 |
6361283 |
Ota et al. |
Mar 2002 |
B1 |
6398516 |
Kawaguchi et al. |
Jun 2002 |
B1 |
Foreign Referenced Citations (2)
Number |
Date |
Country |
0 953 766 |
Nov 1999 |
EP |
2001-12347 |
Jan 2001 |
JP |