Swash plate type compressor

Abstract

A swash plate type compressor including; a rotary drive shaft having an axis of rotation; a swash plate supported by the drive shaft such that the swash plate is inclined or tiltable with respect to a plane perpendicular to the axis of rotation of the shaft; a housing which supports the drive shaft such that the drive shaft is rotatable and axially immovable relative to the housing, which has a plurality of cylinder bores which are located at respective circumferential portions radially spaced from the axis of rotation of the drive shaft and which extend in a direction parallel to the drive shaft; a plurality of pistons each including a head portion slidably engaging a corresponding one of the cylinder bores, and an engaging portion engaging a radially outer portion of opposite surfaces of the swash plate, each piston being reciprocated by the swash plate rotated with the drive shaft; and a plurality of shoes each of which is disposed between one of the opposite surfaces of the swash plate and the engaging portion of each piston for sliding on both of the swash plate and each piston; and wherein the swash plate is formed of a ferrous material and has lubricating films formed on sliding surfaces thereof which slide on the shoes; and wherein each of at least one of the plurality of shoes is a nitrided shoe which is formed of a ferrous material and which has been subjected to a soft nitriding treatment on at least a sliding surface thereof which slides on the swash plate.

What is claimed is:  
     
         1 . A swash plate type compressor including; 
 a rotary drive shaft having an axis of rotation;    a swash plate supported by said rotary drive shaft such that said swash plate is inclined or tiltable with respect to a plane perpendicular to said axis of rotation of said rotary drive shaft;    a housing which supports said rotary drive shaft such that said rotary drive shaft is rotatable and axially immovable relative to said housing, which has a plurality of cylinder bores which are located at respective circumferential portions radially spaced from said axis of rotation of said rotary drive shaft and which extend in a direction parallel to said rotary drive shaft;    a plurality of pistons each including a head portion slidably engaging a corresponding one of said cylinder bores, and an engaging portion engaging a radially outer portion of opposite surfaces of said swash plate, each piston being reciprocated by said swash plate rotated with said rotary drive shaft; and    a plurality of shoes each of which is disposed between one of said opposite surfaces of said swash plate and said engaging portion of said each piston for sliding on both of said swash plate and said each piston;    and wherein said swash plate is formed of a ferrous material and has lubricating films formed on sliding surfaces thereof which slide on said plurality of shoes;    and wherein each of at least one of said plurality of shoes is a nitrided shoe which is formed of a ferrous material and which has been subjected to a soft nitriding treatment on at least a sliding surface thereof which slides on said swash plate.    
     
     
         2 . A swash plate type compressor according to  claim 1 , wherein all of said plurality of shoes are the nitrided shoes.  
     
     
         3 . A swash plate type compressor according to  claim 1 , wherein each of said plurality of pistons is a single-headed piston, and said plurality of shoes engaging said engaging portion of said single-headed piston consist of a pair of shoes which are respectively disposed between said opposite surfaces of said swash plate and said engaging portion of said single-headed piston, and wherein at least the shoe which slides on one of said opposite surfaces of said swash plate on the side of said head portion of said single-headed piston is said nitrided shoe.  
     
     
         4 . A swash plate type compressor according to  claim 1 , wherein said nitrided shoe is formed of a medium-carbon steel or a high-carbon steel.  
     
     
         5 . A swash plate type compressor according to  claim 1 , wherein said nitrided shoe is formed of a high-carbon chrome bearing steel.  
     
     
         6 . A swash plate type compressor according to  claim 1 , wherein said nitrided shoe is formed of a stainless steel.  
     
     
         7 . A swash plate type compressor according to  claim 1 , wherein said soft nitriding treatment is effected according to a salt bath method.  
     
     
         8 . A swash plate type compressor according to  claim 1 , wherein said nitrided shoe has a compound layer formed on a surface thereof by said soft nitriding treatment and having a thickness value in a range of not smaller than 5 μm and not larger than 20 μm.  
     
     
         9 . A swash plate type compressor according to  claim 1 , wherein said nitrided shoe is formed by a forging operation, said soft nitriding treatment being effected after said forging operation.  
     
     
         10 . A swash plate type compressor according to  claim 1 , wherein said swash plate is formed of a spheroidal graphite cast iron.  
     
     
         11 . A swash plate type compressor according to  claim 1 , wherein said lubricating films comprise a solid lubricant and a synthetic resin as a binder.  
     
     
         12 . A swash plate type compressor according to  claim 11 , wherein said solid lubricant includes at least one of molybdenum disulfide (MoS 2 ), boron nitride (BN), tungsten disulfide (WS 2 ), grahite, and polytetrafluoroethylene (PTFE).  
     
     
         13 . A swash plate type compressor according to  claim 11 , wherein said synthetic resin includes at least one of polyamidimide, epoxy resin, polyether ketone, and phenol resin.  
     
     
         14 . A swash plate type compressor according to  claim 1 , wherein said swash plate includes, on at least said sliding surfaces thereof which slides on said shoes, metal sprayed films formed of a material selected from the group consisting of aluminum, copper, an aluminum alloy, and a copper alloy, each of said lubricating films being formed on each of said metal sprayed films.  
     
     
         15 . A swash plate type compressor according to  claim 1 , wherein said swash plate is subjected to a quenching treatment on at least said sliding surfaces thereof which slide on said shoes.  
     
     
         16 . A swash plate type compressor according to  claim 1 , further including a swash plate inclination angle changing device for changing an inclination angle of said swash plate.