Control valve for variable displacement type compressor

Information

  • Patent Grant
  • 6682314
  • Patent Number
    6,682,314
  • Date Filed
    Tuesday, January 22, 2002
    22 years ago
  • Date Issued
    Tuesday, January 27, 2004
    20 years ago
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