Scroll type compressor

Abstract

A scroll type compressor includes a housing, fixed and orbiting scroll members, a rotary shaft, a drive bushing, a plain bearing, a boss, a drive mechanism accommodation space and a compression chamber. The rotary shaft includes an eccentric pin on which the drive bushing is rotatably fitted. The boss is formed in the orbiting scroll member. The drive bushing is slidably inserted in the boss. In the drive mechanism accommodation space formed by the housing, the eccentric pin, the drive bushing and the bearing are disposed and upstream and downstream spaces are defined by the bearing. The compression chamber is formed by the fixed and the orbiting scroll members. A clearance is formed facing the sliding surface of the bearing. A communication passage is formed in the orbiting scroll member for communication between the compression chamber and the upstream space or the clearance and is opened toward the bearing.

What is claimed: 
     
         1 . A scroll type compressor comprising:
 a housing;   a fixed scroll member joined to the housing   an orbiting scroll member adapted to make an orbital motion, and a rotary shaft including an eccentric pin extending toward the orbiting scroll member, the rotary shaft supported in the housing;   a drive bushing rotatably fitted on the eccentric pin;   a boss formed in the orbiting scroll member, the boss in which the drive bushing is slidably inserted;   a bearing formed of a plain bearing, the bearing including a sliding surface, the bearing by which the drive bushing is rotatably supported in the boss;   a drive mechanism accommodation space formed by the housing, the drive mechanism accommodation space in which the eccentric pin, the drive bushing and the bearing are disposed;   an upstream space and a downstream space defined in the drive mechanism accommodation space by the bearing;   a compression chamber formed by the fixed scroll member and the orbiting scroll member;   a clearance formed facing the sliding surface of the bearing for communication between the upstream space and the downstream space; and   a communication passage formed in the orbiting scroll member for communication between the compression chamber and the upstream space or between the compression chamber and the clearance and the communication passage is opened toward the bearing.   
     
     
         2 . The scroll type compressor according to  claim 1 , wherein the communication passage communicates between the compression chamber and the upstream space. 
     
     
         3 . The scroll type compressor according to  claim 2 , wherein the drive bushing has a outer peripheral surface, the bearing includes a first plain bearing located on the outer peripheral surface of the drive bushing and having a tubular shape and a second plain bearing interposed between the first plain bearing and the drive bushing in the radial direction of the eccentric pin and having a tubular shape. 
     
     
         4 . The scroll type compressor according to  claim 1 , wherein the bearing is formed of a single tubular plain bearing and at least one of the outer peripheral surface of the bearing or the inner peripheral surface of the bearing serves as the sliding surface of the bearing. 
     
     
         5 . The scroll type compressor according to  claim 1 , wherein the rotary shaft is driven to rotate in conjunction with a vehicle external drive source. 
     
     
         6 . The scroll type compressor according to  claim 1 , wherein the drive bushing includes a first projecting portion extending in the upstream space toward an end of the orbiting scroll member. 
     
     
         7 . The scroll type compressor according to  claim 1 , wherein the drive bushing includes a second projecting portion extending in the downstream space toward a proximal end of the eccentric pin. 
     
     
         8 . The scroll type compressor according to  claim 1 , wherein the boss includes an end surface extending in the downstream space.