Swash plate type variable displacement compressor

Abstract

A swash plate type variable displacement compressor includes a crank chamber, a rotary shaft, a swash plate, a piston, a supply passage and first and second bleed passages. The supply passage connecting the crank chamber to a discharge pressure region is provided with a displacement control valve. The pressure in the crank chamber is varied by adjusting the opening of the displacement control valve. The first bleed passage connecting the crank chamber to the suction pressure region is provided with a valve. The second bleed passage constantly connecting the crank chamber to the suction pressure region is provided with a throttle. The valve operates to close the first bleed passage according to the magnitude of centrifugal force generated by the rotation of the rotary shaft.

1 . A swash plate type variable displacement compressor comprising:
 a housing including a cylinder block having a cylinder bore formed therein;   a crank chamber formed in the housing;   a rotary shaft extending through the crank chamber, the rotary shaft being rotatably supported by the housing;   a swash plate connected to the rotary shaft, the swash plate being integrally rotatable with and inclinable relative to the rotary shaft;   a piston received in the cylinder bore to be reciprocally movable;   a discharge pressure region for receiving discharge pressure gas;   a suction pressure region for receiving suction pressure gas;   a supply passage connecting the crank chamber to the discharge pressure region, the supply passage being provided with a displacement control valve, wherein the pressure in the crank chamber is varied by adjusting the opening of the displacement control valve to change the inclination angle of the swash plate thereby to control the displacement of the compressor, and   a first bleed passage connecting the crank chamber to the suction pressure region, the first bleed passage being provided with a valve,   a second bleed passage constantly connecting the crank chamber to the suction pressure region, the second bleed passage being provided with a throttle,   wherein the valve operates to close the first bleed passage according to the magnitude of centrifugal force generated by the rotation of the rotary shaft.   
   
   
       2 . The swash plate type variable displacement compressor according to  claim 1 , wherein the first bleed passage includes a passage hole extending in the rotary shaft along the center axis, one end of the passage hole is opened to the crank chamber, the valve is disposed at the other end of the passage hole. 
   
   
       3 . The swash plate type variable displacement compressor according to  claim 2 , wherein the second bleed passage is formed separately from the first bleed passage, wherein the throttle of the second bleed passage is a fixed throttle. 
   
   
       4 . The swash plate type variable displacement compressor according to  claim 2 , wherein the second bleed passage shares at least a part of the first bleed passage. 
   
   
       5 . The swash plate type variable displacement compressor according to  claim 4 , wherein the throttle of the second bleed passage is a fixed throttle provided on the rotary shaft. 
   
   
       6 . The swash plate type variable displacement compressor according to  claim 4 , wherein the valve has a valve body and a valve seat to contact with the valve body, the throttle of the second bleed passage is a groove which is formed on the valve seat. 
   
   
       7 . The swash plate type variable displacement compressor according to  claim 1 , wherein the valve includes a valve body, an urging member urging the valve body toward the opened position and a counterweight, wherein a centrifugal force generated by the rotation of the rotary shaft acts on the counterweight to move the valve body toward the closed position against the urging force of the urging member. 
   
   
       8 . The swash plate type variable displacement compressor according to  claim 6 , wherein a valve hole is formed on the rotary shaft in the radial direction of the rotary shaft, wherein the valve body of the valve is mounted on the rotary shaft to open and close the valve hole. 
   
   
       9 . The swash plate type variable displacement compressor according to  claim 7 , wherein the urging member is a coil spring. 
   
   
       10 . The swash plate type variable displacement compressor according to  claim 1 , wherein the displacement control valve is an electromagnetic valve.