Displacement control valve for clutchless type variable displacement compressor

Abstract

A displacement control valve includes a reciprocation body which has a valve body. The reciprocation body includes a first shaft portion that has the valve body and a second shaft portion that is coaxial with the first shaft portion and inserted in a valve hole. The first shaft portion is located adjacent to a solenoid. The second shaft portion is connected to a pressure sensing mechanism. The second shaft portion and the valve hole define a flow path in which refrigerant freely flows. A throttle portion is formed between the first and second shaft portions and coaxial with the first and second shaft portions. Diameter of an end of the throttle portion adjacent to the second shaft portion is set larger than that of the second shaft portion adjacent to the throttle. Flow rate of the refrigerant in the flow path is suppressed by the throttle portion.

1 . A displacement control valve for a clutchless type variable displacement compressor connected to an external refrigerant circuit, the compressor having a control pressure chamber, the compressor and the external refrigerant circuit having a discharge pressure region, the displacement control valve comprising: 
 a first port in communication with the discharge pressure region;    a second port in communication with the control pressure chamber;    a refrigerant passage connecting the first port to the second port;    a valve hole provided in the refrigerant passage;    a reciprocation body having a valve body for opening and closing the valve hole, the reciprocation body including a first shaft portion that has the valve body and a second shaft portion that is coaxial with the first shaft portion and inserted in the valve hole;    a pressure sensing mechanism for moving the reciprocation body in a direction that causes the valve hole to be opened in accordance with pressure in the discharge pressure region; and    a solenoid for urging the reciprocation body in a direction that causes the valve hole to be closed,    wherein the first shaft portion is located adjacent to the solenoid, the second shaft portion being connected to the pressure sensing mechanism, the second shaft portion and the valve hole defining a flow path in which refrigerant freely flows, a throttle portion being formed between the first and second shaft portions and coaxial with the first and second shaft portions, diameter of an end of the throttle portion adjacent to the second shaft portion being set larger than that of the second shaft portion adjacent to the throttle, flow rate of the refrigerant in the flow path being suppressed by the throttle portion.    
   
   
       2 . The displacement control valve according to  claim 1 , wherein the throttle portion has a tapered surface that is tapered from the first shaft portion toward the second shaft portion.  
   
   
       3 . The displacement control valve according to  claim 1 , wherein the throttle portion has a circumferential surface that is parallel to a direction of movement of the reciprocation body.  
   
   
       4 . The displacement control valve according to  claim 1 , wherein the first and second shaft portions and the throttle portion are formed integrally with each other.  
   
   
       5 . The displacement control valve according to  claim 1 , wherein an axial length of the throttle portion is set to be shorter than a maximum distance of movement of the reciprocation body.  
   
   
       6 . The displacement control valve according to  claim 1 , wherein the refrigerant is carbon dioxide.  
   
   
       7 . The displacement control valve according to  claim 1 , wherein the refrigerant is fluorocarbon-based gas.