Multi-stage compressor and method of manufacturing a multi-stage compressor

Abstract

A multi-stage compressor includes a first bore for a primary compression and a second bore for a secondary compression. A first piston is accommodated in the first bore and a second piston is accommodated in the second bore. A piston ring is attached to the first piston and a second piston ring is attached to the second piston. The inner diameters of the bores, the outer diameters of the pistons, and the outer diameters of the piston rings are equal to each other respectively. Thus, the bores are easily formed. Since only one type of piston and one type of piston ring are required to be manufactured, the manufacture of the above mentioned products is simplified. As a result, manufacture of the compressor becomes easy and the manufacturing cost is reduced.

1 . A multi-stage compressor for compressing fluid in multiple stages, comprising: 
 a plurality of bores for compression at multiple stages; and    a plurality of pistons, each of which is accommodated in one of the bores, wherein the multi-stage compressor is characterized in that the outer diameters of the pistons for compression of at least two different stages are the same.    
     
     
         2 . The multi-stage compressor according to  claim 1 , characterized in that the outer diameters of all pistons for compression at multiple stages are the same.  
     
     
         3 . The multi-stage compressor according to claims  1  or  2 , characterized by a drive chamber accommodating a driving body for driving the pistons, wherein a piston ring is attached at least to one of the pistons corresponding to one of the bores that has the greatest difference between the internal pressure and the pressure of the drive chamber.  
     
     
         4 . The multi-stage compressor according to claims  1  or  2 , characterized in that a piston ring is attached at least to one of the pistons corresponding to one of the bores that has the greatest internal pressure.  
     
     
         5 . The multi-stage compressor according to claims  1  or  2 , characterized in that a piston ring is attached at least to one of the pistons corresponding to one of the bores that has the lowest internal pressure.  
     
     
         6 . The multi-stage compressor according to any one of  claims 1  to  5 , characterized in that the fluid is carbon dioxide.