Compressor housing for supercharger and producing method of the same

Abstract

A compressor housing of a supercharger includes: a housing body housing an impeller therein, and having an inner circumferential recess in a recessed shape on an annular inner circumferential surface along an outer circumference of the impeller; and a sliding member in an annular shape disposed in the inner circumferential recess, an inner circumferential surface of the sliding member having a shroud surface that faces the impeller. The housing body includes a diffuser surface that is disposed circumferentially outward of the shroud surface in a manner as to be continued to the shroud surface. Joint portions in which the housing body and the sliding member are joined through a friction stir welding are provided at a boundary between an outer circumferential end of the sliding member and an inner circumferential end of the diffuser surface of the housing body.

What is claimed is: 
     
         1 . A compressor housing for a supercharger, the compressor housing comprising:
 a housing body housing an impeller, and having an inner circumferential recess in a recessed shape on an annular inner circumferential surface along an outer circumference of the impeller; and   a sliding member having an annular shape, being disposed in the inner circumferential recess, and an inner circumferential surface of the sliding member having a shroud surface that faces the impeller;   wherein the housing body includes a diffuser surface that is disposed circumferentially outward of the shroud surface in a manner as to be continued to the shroud surface, and   joint portions are provided at a boundary between an outer circumferential end of the sliding member and an inner circumferential end of the diffuser surface of the housing body, the housing body and the sliding member being joined through a friction stir welding in the joint portions.   
     
     
         2 . The compressor housing according to  claim 1 , wherein
 each of the joint portions is disposed in a part of the boundary, and   a center of each of the joint portion in a radial direction of the housing body is located circumferentially outward of the boundary.   
     
     
         3 . A producing method of the compressor housing for a supercharger according to  claim 1 , the method comprising:
 an assembling step of assembling the sliding member into the inner circumferential recess of the housing body;   a friction stir welding step of carrying out the friction stir welding at the boundary between the outer circumference end of the sliding member and the inner circumferential end of the diffuser surface of the housing body, and providing each of the joint portion; and   a cutting step of cutting the sliding member and the housing body so as to provide the shroud surface and the diffuser surface, and cutting a surface of each of the joint portion so as to smoothen the surface to be continued to the diffuser surface and the shroud surface.   
     
     
         4 . The producing method according to  claim 3 , wherein
 in the friction stir welding step, the friction stir welding is carried out such that a center of a rotating tool is located circumferentially outward of the boundary when the rotating tool is pushed against a processing target at the boundary.