Variable displacement compressor

Abstract

A variable displacement compressor includes a compressor housing, a rotary shaft, a lug plate, a swash plate, a hinge mechanism, a supply passage and a bleed passage. The compressor housing includes a pressure control chamber having a front region which extends between the swash plate and the lug plate, and a rear region on the opposite side of the swash plate as viewed from the lug plate. The rotary shaft has an axial bleed passage which forms part of the bleed passage and an inlet which is in communication with the axial bleed passage and opened to the front region of the pressure control chamber. At least one of the swash plate and the rotary shaft has a communication passage. The front region and the rear region of the pressure control chamber are in communication with each other through the communication passage.

1 . A variable displacement compressor comprising:
 a compressor housing having a pressure control chamber, a discharge pressure region and a suction pressure region;   a rotary shaft having a front end and a rear end, wherein the rotary shaft is rotatably supported at the front end by a front portion of the compressor housing and at the rear end by a rear portion of the compressor housing, respectively;   a lug plate fixed on the rotary shaft in the pressure control chamber;   a swash plate accommodated in the pressure control chamber;   a hinge mechanism provided between the lug plate and the swash plate, wherein the swash plate is directly supported by the rotary shaft and connected to the lug plate through the hinge mechanism so that the swash plate is rotatable in synchronization with the rotary shaft and the lug plate while inclination angle of the swash plate is variable;   a supply passage communicating with the discharge pressure region and the pressure control chamber; and   a bleed passage communicating with the suction pressure region and the pressure control chamber;   wherein pressure in the pressure control chamber is adjusted by supplying refrigerant gas in the discharge pressure region to the pressure control chamber through the supply passage and releasing the refrigerant gas in the pressure control chamber to the suction pressure region through the bleed passage, thereby to change the inclination angle of the swash plate, whereby displacement of the compressor is controlled,   wherein the pressure control chamber has a front region which extends between the swash plate and the lug plate, and a rear region on the opposite side of the swash plate as viewed from the lug plate,   wherein the rotary shaft has an axial bleed passage which forms part of the bleed passage and an inlet which is in communication with the axial bleed passage and opened to the front region of the pressure control chamber, and   wherein at least one of the swash plate and the rotary shaft has a communication passage, the front region and the rear region of the pressure control chamber being in communication with each other through the communication passage.   
   
   
       2 . The variable displacement compressor according to  claim 1 , wherein the communication passage is formed so as to pass through the swash plate in the direction of thickness thereof. 
   
   
       3 . The variable displacement compressor according to  claim 1 , wherein the communication passage has a circular cross section and its diameter is substantially the same as that of the inlet. 
   
   
       4 . The variable displacement compressor according to  claim 1 , wherein the swash plate has an insertion hole through which the rotary shaft is inserted, wherein the communication passage is provided by a groove, which is formed in an inner peripheral surface of the insertion hole of the swash plate so as to extend through the swash plate in the direction of thickness thereof. 
   
   
       5 . The variable displacement compressor according to  claim 1 , wherein the communication passage is provided by a groove, which is formed in an outer circumferential surface of the rotary shaft and communicates with the inlet. 
   
   
       6 . The variable displacement compressor according to  claim 1 , wherein the rotary shaft has an axial supply passage and an exit passage which is in communication with the axial supply passage and opened in facing relation to the front portion of the compressor housing, wherein the axial supply passage and the exit passage form part of the supply passage. 
   
   
       7 . The variable displacement compressor according to  claim 1 , wherein the compressor housing has a cylinder block and a front housing which define the pressure control chamber, wherein the cylinder block has therethrough a passage which communicates with the pressure control chamber, wherein the passage forms part of the supply passage. 
   
   
       8 . The variable displacement compressor according to  claim 1 , wherein the rotary shaft further comprises:
 a cutout portion adjacent to the inlet extending in the direction of an axis of the rotary shaft, wherein the cutout portion is formed deeper toward the inlet;   a collision portion formed adjacent to the inlet for allowing the refrigerant gas and lubricating oil contained in the refrigerant gas to collide thereagainst; and   a collecting portion also formed adjacent to the inlet, wherein the collecting portion extends so as to intersect with a rotational direction of the rotary shaft and connected to the collision portion.   
   
   
       9 . The variable displacement compressor according to  claim 1 , wherein a maximum inclination angle restricting portion extends from the swash plate, wherein maximum inclination angle of the swash plate is restricted by contact of the maximum inclination angle restricting portion with the lug plate, wherein an opening of the communication passage opened to the front region is located between the maximum inclination angle restricting portion and the hinge mechanism. 
   
   
       10 . The variable displacement compressor according to  claim 9 , wherein the opening of the communication passage is located between the maximum inclination angle restricting portion and the rotary shaft.