Variable displacement type swash plate compressor

Abstract

A variable displacement swash plate type compressor includes a crank chamber, a suction chamber, a drive shaft, a swash plate, and a bleeding passage connecting the crank chamber and the suction chamber. The bleeding passage has an axial passage and first and second radial passages in the drive shaft. The second radial passage opens on an outer peripheral surface of the drive shaft at a position that is closer to the swash plate than the first radial passage. The first radial passage is in constant communication with the crank chamber. The drive shaft has a valve member that is movable in the axial direction with the swash plate. The second radial passage is connected to the crank chamber when the swash plate is at maximum or minimum inclination angles and disconnected from the crank chamber by the valve member when the swash plate is at an intermediate inclination angle.

What is claimed is: 
     
         1 . A variable displacement swash plate type compressor comprising:
 a housing having a discharge chamber, a suction chamber, a crank chamber, and a cylinder bore;   a drive shaft rotatably supported in the crank chamber;   a swash plate disposed in the crank chamber and supported on the drive shaft for rotation with the drive shaft;   a piston reciprocally movable in the cylinder bore with a stroke length depending on an inclination angle of the swash plate, the piston forming a compression chamber in the cylinder bore; and   a control mechanism configured to change the inclination angle of the swash plate between a maximum inclination angle and a minimum inclination angle by a pressure within the crank chamber, the control mechanism having a feeding passage connecting the discharge chamber and the crank chamber, a bleeding passage connecting the crank chamber and the suction chamber, and a displacement control valve configured to adjust at least one of an opening degree of the feeding passage and the bleeding passage, wherein   the bleeding passage includes:
 an axial passage formed in the drive shaft and extending in an axial direction of the drive shaft; 
 a first radial passage formed in the drive shaft, communicating with the axial passage, and extending in a radial direction of the drive shaft to open on an outer peripheral surface of the drive shaft in the crank chamber; and 
 at least one second radial passage formed in the drive shaft, communicating with the axial passage, and extending in the radial direction of the drive shaft to open on the outer peripheral surface of the drive shaft at a position that is closer to the swash plate than the first radial passage is to the swash plate, and 
   a valve member is disposed on the drive shaft, the valve member is movable in the axial direction of the drive shaft with the swash plate,   the first radial passage is in constant communication with the crank chamber, and   the valve member is configured to connect the second radial passage to the crank chamber when the swash plate is at the maximum inclination angle or the minimum inclination angle,  and  to disconnect the second radial passage from the crank chamber when the swash plate is at an intermediate inclination angle that is smaller than the maximum inclination angle and greater than the minimum inclination angle.   
     
     
         2 . The variable displacement swash plate type compressor according to  claim 1 , wherein the first radial passage opens on the outer peripheral surface of the drive shaft in the crank chamber at a position that is closer to the cylinder bore than the second radial passage is to the cylinder bore. 
     
     
         3 . The variable displacement swash plate type compressor according to  claim 1 , wherein
 the housing includes a cylinder block having the cylinder bore and a first housing member cooperating with the cylinder block to define the crank chamber,   the first housing member has a sealing member holding the drive shaft to be rotatable and sealing off the crank chamber from the outside of the first housing member,   the crank chamber accommodates a lug member disposed on the drive shaft and facing the swash plate,   the bleeding passage has a third radial passage formed in the drive shaft, communicating with the axial passage and extending in the radial direction of the drive shaft to open on the outer peripheral surface of the drive shaft between the sealing member and the lug member, and   the third radial passage is in constant communication with the crank chamber.   
     
     
         4 . The variable displacement swash plate type compressor according to  claim 1 , wherein
 the second radial passage includes a plurality of second radial passages, and   the second radial passages open on the outer peripheral surface of the drive shaft at intervals in a circumferential direction of the drive shaft.   
     
     
         5 . The variable displacement swash plate type compressor according to  claim 1 , wherein
 the crank chamber accommodates a lug member disposed on the drive shaft and facing the swash plate,   the swash plate includes a swash plate arm that is configured to transmit a rotary movement of the drive shaft from the lug member to the swash plate,   the swash plate has an insertion hole for receiving the drive shaft and an abutment portion abutting on the outer peripheral surface of the drive shaft in the insertion hole, wherein the abutment portion is disposed opposite to the swash plate arm across an axis of the drive shaft, and   the second radial passage opens on the outer peripheral surface of the drive shaft at a position that is located away from the abutment portion in a circumferential direction of the drive shaft.