Variable Displacement Compressor

Abstract

A variable displacement compressor having a swash plate capable of being changed with inclination angle for converting the rotation of a drive shaft into the reciprocating motion of pistons comprises a plurality of urging means each having one end brought into contact with the swash plate and urging the swash plate in the direction of increasing an inclination angle of the swash plate, wherein the plurality of urging means are constructed so that the number of urgings is increased as the inclination angle of the swash plate is decreased. The freedom of adjustment of the urging force due to the urging means for increasing the inclination angle of the swash plate can be enlarged by a simple structure, and the urging force can be finely adjusted in accordance with the inclination angle of the swash plate. Consequently, the adjustment of the urging force due to the urging means for urging the swash plate in the inclination angle increasing direction can be optimized, and the swash plate can be allowed to perform a desirable operation near the minimum inclination angle.

1 . A variable displacement compressor having a housing in which a discharge chamber, a suction chamber, a crank chamber and cylinder bores are defined therein, pistons disposed in said cylinder bores, a drive shaft supported rotatably in said housing, and a converting mechanism including a swash plate capable of being changed with inclination angle for converting a rotation of said drive shaft into a reciprocating motion of said pistons, which adjusts strokes of said pistons by varying a pressure difference between said crank chamber and said suction chamber, compresses a fluid sucked from said suction chamber into said cylinder bores and discharges a compressed fluid into said discharge chamber, characterized in that a plurality of urging means each having one end brought into contact with said swash plate and urging said swash plate in a direction of increasing an inclination angle of said swash plate are provided, and said plurality of urging means are constructed so that a number of urgings is increased as said inclination angle of said swash plate is decreased. 
     
     
         2 . The variable displacement compressor according to  claim 1 , wherein each of said plurality of urging means is constructed so that an urging force is proportionally increased as said inclination angle of said swash plate is decreased, and by increasing said number of urgings, a gradient of increase of urging force due to said plurality of urging means is increased. 
     
     
         3 . The variable displacement compressor according to  claim 1 , wherein a connecting means is provided for connecting said plurality of urging means integrally. 
     
     
         4 . The variable displacement compressor according to  claim 3 , wherein a positioning structure for positioning said connecting means in an axial direction of said drive shaft is formed on said connecting means and said drive shaft, and at least two of said plurality of urging means are set so as to be different from each other with height in an axial direction from said connecting means. 
     
     
         5 . The variable displacement compressor according to  claim 3 , wherein said plurality of urging means are formed as flat springs, said flat springs are made from a flat spring forming material by pressing, and said connecting means is formed on a remaining part of said flat spring forming material other than said flat springs. 
     
     
         6 . The variable displacement compressor according to  claim 5 , wherein at least two of said plurality of urging means are set so that spring constants thereof are different from each other. 
     
     
         7 . The variable displacement compressor according to  claim 3 , wherein said connecting means and said plurality of urging means are formed so as to surround said drive shaft, said plurality of urging means are arranged at predetermined intervals, and respective tip portions thereof urge said swash plate in said inclination increasing direction and respective base portions thereof are connected integrally with said connecting means. 
     
     
         8 . The variable displacement compressor according to  claim 7 , wherein at least two of said plurality of urging means are set so that spring constants thereof are different from each other. 
     
     
         9 . The variable displacement compressor according to  claim 3 , wherein a minimum inclination angle regulating means for regulating a mechanical minimum inclination angle of said swash plate is provided, and said minimum inclination angle regulating means is connected integrally to said connecting means. 
     
     
         10 . The variable displacement compressor according to  claim 1 , wherein said fluid to be compressed is refrigerant. 
     
     
         11 . The variable displacement compressor according to  claim 1 , wherein said compressor is used in an air conditioning system for a vehicle.