Control valve for compressor

Abstract

To improve the pressure resistance strength of a pressure-sensing section of a control valve for a internal variable control compressor. In the control valve, a stack of snap-acting discs is disposed on a side of a diaphragm forming the pressure-sensing section opposite from a transmitting member. With this arrangement, even if the diaphragm receives large suction pressure Ps, since the snap-acting disc receives suction pressure Ps from the opposite side, the diaphragm is prevented from being broken or deformed. This makes it possible to improve the pressure resistance strength of the pressure-sensing section. As a result, even if the control valve is applied to a refrigeration cycle in which suction pressure Ps becomes high, such as one using carbon dioxide as refrigerant, it is possible to secure sufficient pressure resistance strength.

1 . A control valve for a compressor that varies displacement of the compressor, comprising:
 a body that has a refrigerant passage formed therein;   a valve element that moves to and away from a valve seat formed in said body in order to adjust a flow rate of refrigerant when causing part of discharge refrigerant of said compressor to flow into a control chamber; and   a power element that transmits a driving force which varies according to suction pressure of refrigerant sucked into a suction chamber of said compressor to said valve element via a transmitting member,   wherein said power element comprises a diaphragm that senses said suction pressure to be displaced in an axial direction, and at least one snap-acting disc disposed to support said diaphragm while being in contact with said diaphragm from a side of said diaphragm opposite from a side where said valve element is disposed.   
   
   
       2 . The control valve according to  claim 1 , wherein said transmitting member is slidably inserted into a guide hole formed in said body to be axially supported therein, and at the same time has one end thereof supporting said valve element, and the other end thereof directly or indirectly connected to said diaphragm. 
   
   
       3 . The control valve according to  claim 1 , wherein said snap-acting disc has a central part having a shape convex toward said valve element, and is deformable by having a direction in which said central part is convex inverted using a periphery of said snap-acting disc as a support. 
   
   
       4 . The control valve according to  claim 3 , wherein said power element is formed such that said thin-film diaphragm is sandwiched between an upper housing and a lower housing,
 and wherein said snap-acting disc is disposed in a region surrounded by said upper housing and said diaphragm, and is brought into contact with a side wall of said upper housing such that an edge of a periphery of said snap-acting disc forms the support, thereby being supported thereon.   
   
   
       5 . The control valve according to  claim 4 , wherein a contact surface of said upper housing in contact with said edge of said snap-acting disc is formed to have a tapered shape, and said support is hardly changed in position by an axial displacement of said snap-acting disc. 
   
   
       6 . The control valve according to  claim 5 , wherein said upper housing has an inner wall formed such that said inner wall has a shape substantially matching a shape of said snap-acting disc when said snap-acting disc is deformed by inversion. 
   
   
       7 . The control valve according to  claim 4 , wherein an auxiliary spring is disposed within said upper housing, for urging said snap-acting disc in a valve-opening direction from a side opposite from said diaphragm. 
   
   
       8 . The control valve according to  claim 7 , including a load adjusting structure for adjusting load of said auxiliary spring. 
   
   
       9 . The control valve according to  claim 1 , wherein said power element comprises a plurality of said snap-acting discs, and wherein said snap-acting discs are stacked one upon another by a predetermined number according to a magnitude of suction pressure to be received by said diaphragm. 
   
   
       10 . The control valve according to  claim 9 , wherein a thin film is disposed between said diaphragm and said snap-acting disc, or between said snap-acting discs stacked one upon another by said predetermined number. 
   
   
       11 . The control valve according to  claim 1 , further comprising an another spring that urges said valve element in a valve-closing direction from a side opposite from a side where said power element is disposed,
 a spring-receiving member for supporting said another spring from the side opposite from the side where said valve element is disposed and for adjusting the load of said another spring by being fixed after having being adjusted in position.   
   
   
       12 . A control valve for a compressor that varies displacement of the compressor, comprising:
 a body that has a refrigerant passage formed therein;   a valve element that moves to and away from a valve seat formed in said body in order to adjust a flow rate of refrigerant when causing part of discharge refrigerant of said compressor to flow into a control chamber; and   a power element that transmits a driving force which varies according to suction pressure of refrigerant sucked into a suction chamber of said compressor to said valve element via a transmitting member,   wherein said power element is formed by disposing at least one thin-film snap-acting disc between an upper housing and a lower housing such that said thin-film snap-acting disc is sandwiched between said upper housing and said lower housing, and performing circumferential welding of peripheries thereof, and is configured such that an axial displacement of said snap-acting disc caused by sensing the suction pressure at a central part thereof gives a driving force transmitted to said valve element via said transmitting member.   
   
   
       13 . The control valve according to  claim 12 , wherein said transmitting member is slidably inserted into a guide hole formed in said body to be axially supported therein, and at the same time has one end thereof supporting said valve element, and the other end thereof directly or indirectly connected to said snap-acting disc. 
   
   
       14 . The control valve according to  claim 12 , wherein said snap-acting disc has a central part having a shape convex toward said valve element, and wherein said upper housing has an inner wall having a shape substantially matching a shape of said snap-acting disc when said snap-acting disc is deformed in a direction opposite from a direction in which the central part of said snap-acting disc is convex, using the vicinity of a periphery of said snap-acting disc as a support.