Hollow head piston and compressor having the same

Abstract

A piston includes an engaging portion for engaging with a piston drive mechanism for reciprocating the piston, a hollow head portion with an opening at its one end, and a disc-shaped end plate for closing the opening of the hollow head portion. The piston further includes a central axial protrusion extending in the axial direction. The protrusion is formed integrally with the hollow head portion. The end plate is connected to the central axial protrusion of the hollow head portion. The end plate also has a protrusion protruding towards the central axial protrusion of the hollow head. One of the protrusions has a fitting hole to which the other is press-fitted, thereby connecting the hollow head portion to the end plate to close the opening of the hollow head portion. A diameter of the disc-shaped end plate is smaller than an outer diameter of the cylindrical hollow head portion. Accordingly, the hollow head portion of the piston slides in a cylinder bore of the compressor without any contact between the end plate and the cylinder bore.

What is claimed is:  
     
         1 . A hollow head piston for use in a compressor comprising: 
 a hollow head portion to be slidably fitted in a cylinder bore of the compressor, said hollow head portion having an opening at its end;    an engaging portion for engaging with a piston drive mechanism for reciprocating said head portion in the cylinder bore, said engaging portion being formed at the other end of said head portion opposite to the opening;    an end portion attached to said hollow head portion to close the opening; and    a connecting portion axially extending within said hollow head portion and connecting said hollow head portion to said end portion.    
     
     
         2 . The piston according to  claim 1 , wherein said hollow head portion has a bottom wall and a cylindrical wall extending from the bottom wall, and wherein said connecting portion protrudes from the bottom wall of said hollow head portion.  
     
     
         3 . The piston according to  claim 2 , wherein at least one of the cylindrical wall and the bottom wall has a through hole which connects inside the hollow head portion to outside.  
     
     
         4 . The piston according to  claim 2 , wherein the cylindrical wall of said hollow head portion is coated on its outer surface.  
     
     
         5 . The piston according to  claim 2 , wherein said end portion has a disc having a diameter slightly smaller than an outer diameter of the cylindrical wall of said hollow head portion.  
     
     
         6 . The piston according to  claim 2 , wherein said connecting portion is formed integrally with the bottom wall, said connecting portion having a distal end press-fitted in a fitting hole said end portion has.  
     
     
         7 . The piston according to  claim 6 , wherein the press-fitting connection is accompanied by adhering.  
     
     
         8 . The piston according to  claim 2 , wherein said connecting portion has a tipped fitting hole in which a screwed protrusion provided on said end portion is threaded.  
     
     
         9 . The piston according to  claim 1 , wherein said connecting portion protrudes from said end portion.  
     
     
         10 . The piston according to  claim 1 , wherein said connecting portion comprises protrusions extending from both the bottom wall of said hollow head portion and said end portion, one of the protrusions having u fitting hole the other is fitted in.  
     
     
         11 . A compressor having a hollow head piston, the compressor comprising: 
 a housing having a cylinder bore therein;    a drive shaft rotatably supported by said housing;    a swash plate mounted on said drive shaft; and    a hollow head piston slidably fitted in the cylinder bore of said housing, said piston having a hollow head portion with an opening at its one end, an engaging portion engaged with said swash plate, an end portion closing the opening of the hollow head portion and a connecting portion axially extending within the hollow head portion and coupling the hollow head portion with the end portion.    
     
     
         12 . The compressor according to  claim 11 , wherein said hollow head portion has a bottom wall and a cylindrical wall extending from the bottom wall, and wherein said connecting portion protrudes from the bottom wall of said hollow head portion.  
     
     
         13 . The compressor according to  claim 12 , wherein at least one of the cylindrical wall and the bottom wall has a through hole which connects inside the hollow head portion to outside.  
     
     
         14 . The compressor according to  claim 12 , wherein the cylindrical wall of said hollow head portion is coated on its outer surface.  
     
     
         15 . The compressor according to  claim 12 , wherein said end portion has a disc having a diameter slightly smaller than an outer diameter of the cylindrical wall of said hollow head portion.  
     
     
         16 . The compressor according to  claim 12 , wherein said connecting portion is formed integrally with the bottom wall, said connecting portion having a distal end press-fitted in a fitting hole said end portion has.