Housing Fastening Method

Abstract

An object of the present invention is to provide, by contriving a housing structure, a housing fastening method and turbocharger capable of keeping down a reduction in fastening force applied by a G-coupling even when housings are exposed to high temperature. The present invention provides a turbocharger comprising a turbine 1 including a bladed rotor 1 a rotated by a fluid supplied thereto, a compressor 2 including an impeller 2 a for drawing in air, connected with the bladed rotor 1 a by a rotating shaft 3 a , a turbine housing 1 b constituting an outer shape of the turbine 1 , and a bearing housing 3 rotatably supporting the rotating shaft 3 a , a projecting portion 3 b of the bearing housing 3 being inserted in a recessed portion 1 c of the turbine housing 1 b such that an end face 3 c of the projecting portion 3 b butts against a step portion 1 d of the recessed portion 1 c serving as a stopper face, a flange portion 1 e around the recessed portion 1 c and a flange portion 3 d around the projecting portion 3 b being fastened together by an annular fastener positioned outside, wherein the shapes of the recessed portion 1 c and the projecting portion 3 b are determined by regulating the axial position of the stopper face of the step portion 1 d.

1 . A housing fastening method comprising steps of inserting a projecting portion of a housing in a recessed portion of another housing so that an end face of the projecting position butts against a step portion of the recessed portion serving as a stopper face and that a flange portion around the recessed portion and a flange portion around the projecting portion face each other, and thereafter, fastening the flange portions together by an annular fastener with a grooved portion on its inside adapted to receive the flange portions facing each other, wherein the axial position of the stopper face of the step portion and the shapes of the recessed portion and the projecting portion are determined to ensure that a gap produced between the grooved portion of the fastener and the flange portions does not exceed a specified size even when the housings and the fastener experience thermal expansion during use. 
     
     
         2 . The housing fastener method according to  claim 1 , wherein the axial position of the stopper face of the step portion is set within the axial projected width of the fastener. 
     
     
         3 . The housing fastening method according to  claim 1 , wherein the shape of the projecting portion is determined taking account of the thickness of a thin sheet held between the stopper face of the step portion and the end face of the projecting portion. 
     
     
         4 . The housing fastening method according to  claim 1 , wherein when the housings are likely to experience different degrees of thermal expansion during use, the flange portion of the housing which is likely to experience a smaller degree of thermal expansion is formed to be greater in outside diameter than the flange portion of the housing which is likely to experience a greater degree of thermal expansion. 
     
     
         5 . The housing fastening method according to  claim 1 , wherein an axial distance Az from a contact position at which the fastener contacts the flange portion around the recess portion to the stopper face of the step portion and an axial distance Bz from a contact position at which the fastener contacts the flange portion around the projecting portion to the end face of the projecting portions are determined to meet the condition 0≦Cg−C≦allowable limit k, where C is an axial distance between the contact positions on the flange portions defined by an expression C=t+Bz−Az, on the basis of said axial distances Az and Bz, and Cg is an axial distance between the contact positions on the fastener. 
     
     
         6 . The housing fastening method according to  claim 5 , wherein the allowable limit k is set on the basis of the allowable size for a gap produced between the fastener and the contact position on the flange portion at a specified temperature. 
     
     
         7 . The housing fastening method according to  claim 5 , wherein the allowable limit k is set to meet the condition 0≦k<0.0388/cos(θ/2), where θ is an angle of divergence of a pair of support portions of the fastener. 
     
     
         8 . A turbocharger comprising a turbine including a bladed rotor rotated by a fluid supplied thereto, a compressor including an impeller for drawing in air, connected with the bladed rotor by a rotating shaft, a turbine housing constituting an outer shape of the turbine, and a bearing housing rotatably supporting the rotating shaft, a projecting portion of the bearing housing being inserted in a recessed portion of the turbine housing such that an end face of the projecting position butts against a step portion of the recessed portion serving as a stopper face and that a flange portion around the recessed portion and a flange portion around the projecting portion face each other, the flange portions being fastened together by an annular fastener with a grooved portion on its inside adapted to receive the flange portions facing each other, wherein
 the bearing housing and the turbine housing are fastened together by the fastener by employing the housing fastening method according to  claim 1 .