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 mum. 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.

Description

[0001] The present invention relates to a displacement type compressor, and in particular to surface treatment preferable for enhancing the efficiency of a scroll compressor used in an air-conditioning unit, a refrigerator and an air compressor unit.RELATED ART[0002] Conventionally, various surface treatment methods have been proposed for a displacement type compressor in which 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, and in particular, for a scroll type compressor in which a pair of scrolls (laps) angularly shifted from each other and meshed with each other are subjected to circular motion, relative to each other so as to move a closed space defined between both laps toward the center part while the volume thereof is compressed to discharge the compressed fluid from the center part. The purpose of the surface treatment is to decrease leakage of fluid to be compress...

AI Technical Summary

Benefits of technology

[0013] Since this stannate compound coating film is formed not by coating the member with a material different from that of the member as a plated coating film, but by forming a compound with the member, it is possible to prevent peel-off of the coating film from the member or the like. In this arrangement, although sufficient sealability and conformability can be obtained only by coating either one of the stator and the rotor with the stannate coating film, but the similar characteristic can be obtained by coating both of them. This stannate compound coating film is particularly preferable for the member made of a material selected from an iron group including cast iron and carbon steel. In this case, the compound is Fe--Sn compound which exhibits excellent conformability.

Problems solved by technology

In such a case-that a slidable part of a scroll type compressor is formed on its surface with a coating film such-as a plating coating film, made of a material different from the material of the member, the temperature and the pressure increase during compression stroke, various conditions such that a temperature difference and a pressure differential are caused between the outer peripheral part and the center part, change, and accordingly, repetitive stress is applied to the coating film which therefore cracks in long time use so that the coating film peels off.

In the most worst case, fragments of the peeled-off coating film would cause eccentric abrasion.

However, the phosphate manganese coating film (leubrite coating film) has a relatively high hardness and high surface roughness.

Accordingly, a relatively long time is required until the slidable parts become conformable against each other during assembly of the scroll type compressor, thereby the productivity thereof has been inferior.

This deformation, in particular, the deformation of the rotary scroll in the lap-heightwise direction, causes the gap between the rotary scroll and the stationary scroll associated with the former to increase, and as a result, leakage increases so that the efficiency of the compressor is greatly lowered.

Thus, unless this part is worn by operating the compressor for a long time, the gap cannot become narrow, and accordingly, the efficiency cannot be increased.

Thus, it is difficult to enhance the efficiency of the compressor.

Further, should it be higher than 95 deg. C., the reaction within the mixed solution would be promoted before the reaction with the member, thereby it is difficult to stably form the compound with the member.

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