Displacement type compressor and method of forming coating film

Abstract

A scroll type compressor comprises a stationary scroll and a rotary scroll which is assembled with the stationary scroll so as to define a closed space, the outer surface of the rotary scroll 22 is formed thereon with a tin compound film containing a tin compound and having a thickness of 50 μm. Such a coating film is never peeled off from a member even after long time operation, and is excellent in sealability and conformability, in the displacement type compressor.

What is claimed is:  
     
         1 . A displacement type fluid compressor wherein a closed space defined between a stator and a rotor is gradually decreased in association with motion of the rotor so as to suck, compress and discharge fluid, characterized in that at least one of surfaces of parts where the stator and the rotor make contact with each other is formed thereon with a tin compound coating film containing a tin compound.  
     
     
         2 . A displacement type fluid compressor as set forth in  claim 1 , characterized in that the tin compound coating film has a thickness of not less than 20 μm.  
     
     
         3 . A displacement type fluid compressor as set forth in  claim 1 , characterized in that said tin compound is a compound of tin and metal from which the stator or the rotor is formed.  
     
     
         4 . A displacement type fluid compressor as set forth in  claim 1 , characterized in that each of the outer surfaces of the stator and the rotor is coated with the tin compound coating film.  
     
     
         5 . A displacement type fluid compressor as set forth in  claim 2 , characterized in that the tin compound is an iron group material and a compound of tin.  
     
     
         6 . A displacement type fluid compressor as set forth in any one of  claims 1  to  4 , characterized in that the tin compound coating film is formed in a mixed solution composed of stannate as a main component.  
     
     
         7 . A displacement type fluid compressor as set forth in  claim 5 , characterized in that the stannate is potassium stannate.  
     
     
         8 . An air-conditioning apparatus using the compressor as set forth in any one of  claims 1  to  7 .  
     
     
         9 . A method of forming a coating film containing a tin compound, on at least one of a stator and a rotor of a displacement type compressor in which a closed space defined between the stator and the rotor is gradually decreased in association with motion of the rotor so as to suck, compress and discharge fluid, characterized by the steps of alkaline-degreasing an objective member, washing thus alkaline-degreased objective member with pure water; oxidation-etching the objective member washed with pure water, dipping the objective member oxidation-etched in a mixed solution containing stannate as a main component, so as to form a tin compound coating film, washing the objective member formed with the tin compound coating film with pure water, and drying and baking the objective member washed with pure water.