Piston for fluid machine and the fluid machine having the same

Abstract

A piston is used in a fluid machine. The fluid machine has a drive shaft and a cam plate operatively connected to the drive shaft. The drive shaft integrally rotates with the cam plate in a housing. The piston has a head portion, a neck portion, a receiving wall and a guide wall. The head portion is accommodated in a cylinder bore in the housing. The neck portion is operatively connected to the cam plate. The receiving wall integrally connects the head portion and the neck portion on the drive shaft side. The receiving wall is formed substantially on a preceding side in a rotating direction of the cam plate. The guide wall integrally connects the head portion and the neck portion on an opposite side of the drive shaft side. The guide wall is formed substantially on a following side in the rotating direction of the cam plate.

What is claimed is:  
     
         1 . A piston to be used in a fluid machine, the fluid machine having a drive shaft and a cam plate operatively connected to the drive shaft, the drive shaft integrally rotating with the cam plate in a housing, the piston comprising: 
 a head portion accommodated in a cylinder bore formed in the housing;    a neck portion operatively connected to the cam plate through a pair of shoes;    a receiving wall integrally connecting the head portion and the neck portion on the drive shaft side, the receiving wall being formed substantially on a preceding side in a rotating direction of the cam plate; and    a guide wall integrally connecting the head portion and the neck portion on an opposite side of the drive shaft side, the guide wall being formed substantially on a following side in the rotating direction of the cam plate.    
     
     
         2 . The piston according to  claim 1  wherein the piston is integrally molded as a whole by a die unit that includes a movable die, which is movable only in a direction.  
     
     
         3 . The piston according to  claim 1  further comprising a reinforcement for connecting the receiving wall to the guide wall.  
     
     
         4 . The piston according to  claim 3  wherein the receiving wall, the guide wall and the reinforcement substantially define a shape of S in a cross section along a plane perpendicular to a longitudinal axis of the piston.  
     
     
         5 . The piston according to  claim 1  wherein the piston is viewed in a cross section along a plane perpendicular to the axial direction of the drive shaft in a such manner that the drive shaft is rotated clockwise, an outer circumferential surface of the receiving wall being formed at least over a range of 4 o'clock to 6 o'clock, an outer circumferential surface of the guide wall being formed at least over a range of 10 o'clock to 12 o'clock, the 12 o'clock being located at the top of the cross section.  
     
     
         6 . The piston according to  claim 5  wherein the outer circumferential surface of the receiving wall is formed substantially over a range of 3 o'clock to 6 o'clock, the outer circumferential surface of the guide wall being formed substantially over a range of 9 o'clock to 12 o'clock.  
     
     
         7 . The piston according to  claim 6  further comprising a reinforcement for connecting the receiving wall at the position of 3 o'clock to the guide wall at the position of 9 o'clock.  
     
     
         8 . The piston according to  claim 6  further comprising a reinforcement for connecting the receiving wall at the position of 6 o'clock to the guide wall at the position of 12 o'clock.  
     
     
         9 . The piston according to  claim 1 , wherein the receiving wall and the guide wall are formed substantially symmetrically with respect to a longitudinal axis of the piston.  
     
     
         10 . The piston according to  claim 1 , wherein an outer circumferential surface of the receiving wall and the guide wall is slidable relative to an inner circumferential surface of the cylinder bore.  
     
     
         11 . The piston according to  claim 1  wherein the piston as a whole is made of aluminum.  
     
     
         12 . A fluid machine comprising: 
 a housing;    a drive shaft rotatably supported in the housing; and    a piston operatively connected to the drive shaft for exerting pressure on fluid, the piston further including; 
 a head portion accommodated in a cylinder bore formed in the housing;  
 a neck portion operatively connected to the drive shaft;  
 a receiving wall connecting the head portion and the neck portion on the drive shaft side, the receiving wall being formed substantially on a preceding side in a rotating direction of the drive shaft; and  
 a guide wall connecting the head portion and the neck portion on an opposite side of the drive shaft side, the guide wall being formed substantially on a following side in the rotating direction of the drive shaft.  
   
     
     
         13 . The piston according to  claim 12  wherein the piston is integrally molded as a whole by a die unit that includes a movable die, which is movable only in a direction.  
     
     
         14 . The piston according to  claim 12  further comprising a reinforcement for connecting the receiving wall to the guide wall.  
     
     
         15 . The piston according to  claim 14  wherein the receiving wall, the guide wall and the reinforcement substantially define a shape of S in a cross section along a plane perpendicular to a longitudinal axis of the piston.  
     
     
         16 . The piston according to  claim 12  wherein the piston is viewed in a cross section along a plane perpendicular to the axial direction of the drive shaft in a such manner that the drive shaft is rotated clockwise, an outer circumferential surface of the receiving wall being formed at least over a range of 4 o'clock to 6 o'clock, an outer circumferential surface of the guide wall being formed at least over a range of 10 o'clock to 12 o'clock, the 12 o'clock being located at the top of the cross section.  
     
     
         17 . The piston according to  claim 12  wherein the piston as a whole is made of aluminum.  
     
     
         18 . A piston type compressor comprising: 
 a housing;    a drive shaft rotatably supported in the housing;    a cam plate supported by the drive shaft, the cam plate being rotated by the rotation of the drive shaft; and    a plurality of pistons operatively connected to the cam plate for compressing refrigerant gas, the rotation of the cam plate being converted into a reciprocating movement of the piston, the piston further including, 
 a head portion accommodated in a cylinder bore formed in the housing;  
 a neck portion operatively connected to the cam plate;  
 a receiving wall connecting the head portion and the neck portion on the drive shaft side, the receiving wall being formed substantially on a preceding side in a rotating direction of the cam plate; and  
 a guide wall connecting the head portion and the neck portion on an opposite side of the drive shaft side, the guide wall being formed substantially on a following side in the rotating direction of the cam plate.  
   
     
     
         19 . The piston according to  claim 18  wherein the piston is as a whole integrally molded by a die unit that includes a movable die, which is movable only in a direction.  
     
     
         20 . The piston according to  claim 18  further comprising a reinforcement for connecting the receiving wall to the guide wall.  
     
     
         21 . The piston according to  claim 20  wherein the receiving wall, the guide wall and the reinforcement substantially define a shape of S in a cross section along a plane perpendicular to a longitudinal axis of the piston.  
     
     
         22 . The piston according to  claim 18  wherein the piston is viewed in a cross section along a plane perpendicular to the axial direction of the drive shaft in a such manner that the drive shaft is rotated clockwise, an outer circumferential surface of the receiving wall being formed at least over a range of 4 o'clock to 6 o'clock, an outer circumferential surface of the guide wall being formed at least over a range of 10 o'clock to 12 o'clock, the 12 o'clock being located at the top of the cross section.  
     
     
         23 . The piston according to  claim 22  wherein the outer circumferential surface of the receiving wall is formed substantially over a range of 3 o'clock to 6 o'clock, the outer circumferential surface of the guide wall being formed substantially over a range of 9 o'clock to 12 o'clock.  
     
     
         24 . The piston according to  claim 23  further comprising a reinforcement for connecting the receiving wall at the position of 3 o'clock to the guide wall at the position of 9 o'clock.  
     
     
         25 . The piston according to  claim 23  further comprising a reinforcement for connecting the receiving wall at the position of 6 o'clock to the guide wall at the position of 12 o'clock.  
     
     
         26 . The piston according to  claim 18  wherein the piston as a whole is made of aluminum.