Compressor housing for turbocharger and method for manufacturing the same

Abstract

A compressor housing for a turbocharger including a refrigerant flow path and a recirculation part, which is dividably composed of a scroll piece and a shroud piece. The refrigerant flow path is formed as an annular space that is defined by a first flow-path formation part of the scroll piece and a second flow-path formation part of the shroud piece that are fitted with each other. In the refrigerant flow path, a first press-fitting portion of the shroud piece is press-fitted into a first press-fitted portion of the scroll piece to form an inner circumferential seal part, and a second press-fitting portion of the shroud piece is press-fitted into a second press-fitted portion of the scroll piece to form an outer circumferential seal part. The recirculation part recirculates part of the air which has reached the shroud part to an upstream of the compressor impeller.

1 . A compressor housing for a turbocharger configured to house a compressor impeller, the compressor housing comprising:
 an intake port formation part that defines an intake port configured to suck in air toward the compressor impeller;   a shroud part that surrounds the compressor impeller in a circumferential direction and has a shroud surface facing the compressor impeller;   a diffuser part that is formed on an outer circumferential side of the compressor impeller in the circumferential direction and forms a diffuser passage configured to allow compressed air discharged from the compressor impeller to pass therethrough;   a scroll chamber formation part that forms a scroll chamber configured to guide the compressed air passing through the diffuser passage to outside;   a refrigerant flow path that is formed along the diffuser part in the circumferential direction, and allows a refrigerant for cooling the diffuser part to pass therethrough; and   a recirculation part configured to recirculate part of the air which has been sucked in from the intake port and reached the shroud part to an upstream of the compressor impeller,   wherein the compressor housing is dividably composed of a scroll piece including at least part of the intake port formation part and at least part of the scroll chamber formation part, and a shroud piece including at least part of the scroll chamber formation part, the diffuser part, and the shroud part, and being press-fitted into an inside of the scroll piece in a shaft direction,   wherein the refrigerant flow path is formed as an annular space that is defined by a first flow-path formation part of the scroll piece and a second flow-path formation part of the shroud piece, the first flow-path formation part and the second flow-path formation part being formed respectively at each opposing part of the scroll piece and the shroud piece which oppose each other,   wherein the first flow-path formation part and the second flow-path formation part are fitted with each other at an inner circumferential seal part configured to seal the refrigerant flow path on the inner circumferential side of the refrigerant flow path and at an outer circumferential seal part configured to seal the refrigerant flow path on the outer circumferential side of the refrigerant flow path,   wherein the inner circumferential seal part is formed by press-fitting a first press-fitting portion of the shroud piece into a first press-fitted portion of the scroll piece,   wherein the outer circumferential seal part is formed by press-fitting a second press-fitting portion of the shroud piece into a second press-fitted portion of the scroll piece, and   wherein the recirculation part includes: a recirculation chamber as a space that is defined by a first recirculation chamber formation part of the scroll piece and a second recirculation chamber formation part of the shroud piece, the first recirculation chamber formation part and the second recirculation chamber formation part being formed respectively at each opposing part of the scroll piece and the shroud piece which oppose each other; a communication part that is open at the shroud surface and is communicated with the recirculation chamber; and a blowout part that is open at the scroll piece, or in an upstream position of the compressor impeller of the shroud piece, and is communicated with the recirculation chamber.   
     
     
         2 . The compressor housing for a turbocharger according to  claim 1 , wherein the scroll piece and the shroud piece have in common a contact portion configured to perform positioning at the press-fitting by contacting the scroll piece and the shroud piece in a state of opposing in a shaft direction. 
     
     
         3 . A method for manufacturing the compressor housing for a turbocharger according to  claim 1 , the method comprising:
 molding the scroll piece and the shroud piece by die-casting;   forming the first and second press-fitted portions in the scroll piece, and the first and second press-fitting portions and the communication part in the shroud piece, respectively by machining; and   assembling the shroud piece into the scroll piece while forming the refrigerant flow path and the recirculation part by forming the inner circumferential seal part and the outer circumferential seal part, the inner circumferential seal part being formed by press-fitting the first press-fitting portion into the first press-fitted portion, and the outer circumferential seal part being formed by press-fitting the second press-fitting portion into the second press-fitted portion.   
     
     
         4 . A method for manufacturing the compressor housing for a turbocharger according to  claim 2 , the method comprising:
 molding the scroll piece and the shroud piece by die-casting;   forming the first and second press-fitted portions in the scroll piece, and the first and second press-fitting portions and the communication part in the shroud piece, respectively by machining; and   assembling the shroud piece into the scroll piece while forming the refrigerant flow path and the recirculation part by forming the inner circumferential seal part and the outer circumferential seal part, the inner circumferential seal part being formed by press-fitting the first press-fitting portion into the first press-fitted portion, and the outer circumferential seal part being formed by press-fitting the second press-fitting portion into the second press-fitted portion.