Variable displacement swash plate type compressor

Abstract

A variable displacement swash plate type compressor includes a displacement control valve. The displacement control valve includes a drive force transmitting member, a valve member having a first valve body, a valve chamber, which accommodates the first valve body, an accommodating chamber, which communicates with a control pressure chamber, a pressure sensing mechanism, which adjusts the valve opening degree of the first valve body, a communicating chamber, which is located on the opposite side of the pressure sensing mechanism from the valve chamber, and a second valve body, which is located in the pressure sensing mechanism and selectively opens and closes the communicating chamber. When the current supply to the electromagnetic solenoid is stopped and the pressure in the suction pressure zone in the communicating chamber is higher than a predetermined pressure, the pressure sensing mechanism contracts to open the second valve body.

1 . A variable displacement swash plate type compressor comprising:
 a housing having a crank chamber;   a swash plate accommodated in the crank chamber, wherein the swash plate receives a drive force from a rotary shaft to rotate and is capable of changing its inclination angle relative to the rotary shaft;   a piston engaged with the swash plate;   a movable body, which is coupled to the swash plate and changes the inclination angle of the swash plate;   a control pressure chamber defined in the housing by the movable body, wherein pressure in the control pressure chamber is changed by introducing control gas therein so that the movable body is moved in the axial direction of the rotary shaft; and   a displacement control valve that controls the pressure in the control pressure chamber, wherein   the piston is reciprocated by a stroke that corresponds to the inclination angle of the swash plate,   the displacement control valve includes:
 a drive force transmitting member, which is driven by an electromagnetic solenoid; 
 a valve member having a first valve body, wherein the first valve body adjusts an opening degree of discharge passage that extends from the control pressure chamber to a suction pressure zone; 
 a valve chamber, which accommodates the first valve body and communicates with the suction pressure zone; 
 an accommodating chamber, which communicates with the control pressure chamber; 
 a pressure sensing mechanism, which is accommodated in the accommodating chamber and integrated with the valve member, wherein, by sensing a pressure in the suction pressure zone that acts on the valve member, the pressure sensing mechanism extends or contracts in the moving direction of the drive force transmitting member, thereby adjusting the valve opening degree of the first valve body; 
 a communicating chamber, which is located on the opposite side of the pressure sensing mechanism from the valve chamber and communicates with the suction pressure zone; and 
 a second valve body, which is located in the pressure sensing mechanism and selectively opens and closes the communicating chamber, and 
   when a current supply to the electromagnetic solenoid is stopped and the pressure in the suction pressure zone in the communicating chamber is higher than a predetermined pressure, the pressure sensing mechanism contracts in the moving direction of the drive force transmitting member, thereby opening the second valve body.   
     
     
         2 . The variable displacement swash plate type compressor according to  claim 1 , further comprising a valve opening spring, which is provided in the communicating chamber and urges the pressure sensing mechanism and the valve member toward the electromagnetic solenoid. 
     
     
         3 . The variable displacement swash plate type compressor according to  claim 1 , wherein the displacement control valve further includes:
 a valve housing; and   a valve seat member, which is formed separately from the valve housing, wherein the valve seat member has a valve seat, on which the first valve body is seated.   
     
     
         4 . The variable displacement swash plate type compressor according to  claim 3 , further comprising an urging spring, which is provided in the accommodating chamber and urges the valve seat member toward the first valve body. 
     
     
         5 . The variable displacement swash plate type compressor according to  claim 1 , wherein the communicating chamber is open on the side opposite to the accommodating chamber and communicates with the suction pressure zone. 
     
     
         6 . The variable displacement swash plate type compressor according to  claim 1 , wherein a contraction allowance of the pressure sensing mechanism in the moving direction of the drive force transmitting member is set to be smaller than a movable range of the drive force transmitting member. 
     
     
         7 . The variable displacement swash plate type compressor according to  claim 1 , wherein the piston is a double-headed piston. 
     
     
         8 . The variable displacement swash plate type compressor according to  claim 1 , wherein the rotary shaft receives drive force from an external drive source via the power transmission mechanism, which is a clutchless mechanism.