Piston for swash plate type compressor

Abstract

The object of the present invention is to offer not only a compressor which is compact and reduced in weight, but also its piston whose neck portion is increased in strength at a time. A single-headed piston for a swash plate type compressor has a hollow head portion, a pair of engaged portions engaged with a swash plate, and a neck portion connected to the pair of the engaged portions at the outer peripheral side of the swash plate. The pair of the engaged portions sandwiches both of the outer peripheral end surfaces of the swash plate through a pair of hemispherical shoes. A pair of concave portions having a pair of concave spherical surfaces is formed on the surfaces facing each other of the pair of the engaged portions so as to receive a convex spherical surfaces of shoes slidably. The pair of concave portions have a common spherical center. The spherical center is positioned on the plane which includes the central axis of the head portion and is parallel in the extending direction of the pair of the engaged portions, and is positioned deviatedly to the opposite side (to the radially inner side of the compressor) to the neck portion from the central axis of the head portion. It is desired that the spherical center is positioned deviatedly to the radially inner side of the compressor by equal to or greater than {fraction (1/30)} of the diameter of the head portion. The thickness of the neck portion is increased, and the bending strength of the neck portion is improved. In addition, the diameter of the swash plate is to be compact. Therefore, the compressor is reduced in weight, and is improved in its durability.

What is claimed is:  
     
         1 . A piston for use in a swash plate type compressor comprising: 
 a pair of engaged portions operatively engaged to both of the outer peripheral end surfaces of a swash plate through a shoe device, respectively;    a neck portion connected to both said pair of engaged portions at the outer peripheral side of the swash plate; and    a head portion disposed within a cylinder bore slidably, wherein the spherical center of a pair of concave spherical surfaces of engaged portions, which are engaged with convex spherical surfaces of said shoe device, is positioned deviatedly to the drive shaft from the central axis of said head portion.    
     
     
         2 . The piston for use in a swash plate type compressor according to    claim 1   , 
 wherein said spherical center is positioned deviatedly to the drive shaft from said central axis of said head portion by equal to or greater than {fraction (1/30)} of the diameter of said head portion.    
     
     
         3 . The piston for use in a swash plate type compressor according to    claim 1   , 
 wherein said pair of engaged portions and said neck portion have a single head portion.    
     
     
         4 . The piston for use in a swash plate type compressor according to    claim 1   , 
 wherein the pair of concave spherical surfaces of said engaged portions have a common spherical center.    
     
     
         5 . The piston for use in a swash plate type compressor according to    claim 1   , 
 wherein a back surface of said neck portion is positioned nearer to said central axis than an outer peripheral surface of said head portion of said piston.    
     
     
         6 . The piston for use in a swash plate type compressor according to    claim 1   , 
 wherein the end, being farther from said neck portion, of an engaged portion at said head portion side is positioned within an imaginary cylindrical surface extending to include an outer peripheral surface of said head portion.    
     
     
         7 . The piston for use in a swash plate type compressor according to    claim 1   , 
 wherein said neck portion has at least a rib extending in the axial direction on said back surface.    
     
     
         8 . A swash plate type compressor comprising: 
 a swash plate rotated so as to incline with respect to an axis of a drive shaft;    a housing having cylinder bores formed in parallel with and around the axis of the drive shaft;    a pair of engaged portions operatively engaged to both of the outer peripheral end surfaces of a swash plate through a shoe device, respectively;    a neck portion connected to both said pair of engaged portions at the outer peripheral side of the swash plate; and    a head portion disposed within a cylinder bore slidably, wherein the spherical center of a pair of concave spherical surfaces of engaged portions, which are engaged with convex spherical surfaces of said shoe device, is positioned deviatedly to the drive shaft from the central axis of said head portion.    
     
     
         9 . The swash plate type compressor according to    claim 8   , 
 wherein said shoe device is a pair of substantially hemispherical shoes including said convex spherical surfaces and the sliding surfaces which are substantially plane.    
     
     
         10 . The swash plate type compressor according to    claim 9   , further comprising a device for adjusting inclination angle of said swash plate, wherein the pair of concave spherical surfaces of said engaged portions has a common spherical center.  
     
     
         11 . The swash plate type compressor according to    claim 8   , further comprising a device for adjusting inclination angle of said swash plate, wherein the pair of concave spherical surfaces of said engaged portions has a common spherical center.