Scroll Fluid Machine

Abstract

Scroll fluid machine ( 1 ) in which the dislodgement of a slide bush ( 56 ) and a spring ( 61 ), which are provided in an eccentric bush ( 36 ), is prevented. Provided in receiving hole ( 58 ) of eccentric bush ( 36 ) are slide bush ( 56 ), which is movable in the direction of eccentricity, and spring ( 61 ), which biases slide bush ( 56 ) in a moving direction. A spring holding section ( 56 b ) and engagement projections ( 56 a ) are formed on slide bush ( 56 ). After slide bush ( 56 ) is placed in the receiving hole ( 58 ), engagement projections ( 56 a ) engage with eccentric bush ( 36 ) in a state in which slide bush ( 56 ) has been moved by the biasing force of spring ( 61 ), thus preventing slide bush ( 56 ) from falling off the receiving hole ( 58 ), and the spring holding section ( 56 b ) prevents the spring ( 61 ) from falling off the receiving hole ( 58 ).

1 . A scroll fluid machine comprising:
 a scroll unit which is composed of a fixed scroll and a movable scroll each having spiral wraps formed on base surfaces of base plates thereof, the spiral wraps opposing each other, and in which a working chamber of a working fluid is formed between the wraps of the fixed scroll and the movable scroll by an orbital motion of the movable scroll about an axis of the fixed scroll;   a frame having a pedestal which orbitably supports the movable scroll at an outer peripheral portion of a rear surface on the opposite side from the base surface of the movable scroll; and   a support mechanism which orbitably supports the movable scroll at a central portion of the rear surface of the movable scroll,   wherein the support mechanism includes:   a boss provided on the rear surface of the movable scroll;   an eccentric bush slidably and rotatably fitted in the boss;   a slide bush placed in a receiving hole formed in the eccentric bush such that the slide bush is movable in a direction of eccentricity of the eccentric bush;   a fixed shaft which is provided protruding from a bottom surface of the frame and which is slidably and rotatably inserted in an insertion hole formed in the slide bush; and   a spring which is interposed between the slide bush in the receiving hole and the eccentric bush and which biases the slide bush in a direction in which the slide bush moves,   a spring holding section and engagement projection which protrudes outward are formed on the slide bush, and   the engagement projection engages with the eccentric bush in a state in which the slide bush has been placed in the receiving hole and then moved by a biasing force of the spring, thereby preventing the slide bush from falling off the receiving hole, and the spring holding section prevents the spring from falling off the receiving hole.   
     
     
         2 . The scroll fluid machine according to  claim 1 , wherein
 the receiving hole is formed passing through the eccentric bush,   the engagement projections are formed on both end portions of the slide bush and   the engagement projections engage with both opening edge portions of the receiving hole of the eccentric bush in a state in which the slide bush has been moved by the biasing force of the spring.   
     
     
         3 . The scroll fluid machine according to  claim 1  or  2 , wherein
 the receiving hole is composed of a large-diameter section formed passing through the eccentric bush and a small-diameter section continuing from the large-diameter section in the direction of eccentricity, 
 the engagement projections are formed on peripheral edges at both ends of the slide bush, and 
 in a state in which the slide bush has been placed in the large-diameter section of the receiving hole and then the slide bush has been moved into the small-diameter section by the biasing force of the spring, the portions of the engagement projections positioned in the direction of the movement engage with both opening edge portions of the small-diameter section of the receiving hole, and the portions of the engagement projections positioned on the opposite side from the direction of the movement double as the spring holding section. 
 
     
     
         4 . The scroll fluid machine according to  claim 1 , wherein
 the receiving hole is formed passing through the eccentric bush,   the engagement projection is formed on the other end portion of the slide bush and engages with an opening edge portion of the receiving hole in a state in which the slide bush has been moved by the biasing force of the spring, and   one end portion of the slide bush is provided with a fastener for preventing the slide bush and the spring from falling off, the fastener being positioned outside the receiving hole.   
     
     
         5 . The scroll fluid machine according to  claim 1 , wherein the spring holding section has a sloping surface that inclines downward toward an opening direction of the receiving hole. 
     
     
         6 . The scroll fluid machine according to  claim 1 ,
 wherein the scroll unit includes:   an expansion section which expands a working fluid in an expansion chamber formed between the wraps of the fixed scroll and the movable scroll thereby to orbit the movable scroll to recover motive power; and   a compression section which compresses the working fluid by the motive power, which has been recovered by the expansion section, in a compression chamber formed between the wraps of the both scrolls.   
     
     
         7 . The scroll fluid machine according to  claim 1 , wherein carbon dioxide is used as the working fluid.