Patent ID: 7014418

Claim:
A turbocharger, comprising: a center housing defining a bore extending therethrough in an axial direction, with bearings mounted in the bore and a rotatable shaft supported in the bearings, the shaft having opposite ends, the center housing having axially opposite sides; a compressor wheel mounted on one end of the shaft; a turbine wheel mounted on the other end of the shaft; a compressor housing enclosing the compressor wheel and having opposite first and second sides, the second side mounted to one of the sides of the center housing; a turbine housing mounted to the other side of the center housing enclosing the turbine wheel, the turbine housing defining an annular chamber surrounding the turbine wheel for receiving exhaust gas and directing the exhaust gas radially inwardly into the turbine wheel, the turbine housing defining an outlet for the exhaust gas extending in the axial direction away from the center housing; the compressor wheel having a first-stage impeller and a second-stage impeller arranged back-to-back; the compressor housing defining a first-stage inlet extending in the axial direction into the first side of the compressor housing for supplying air into the first-stage impeller, and defining a second-stage inlet extending opposite to the axial direction into the second side of the compressor housing for supplying air into the second-stage impeller; the compressor housing defining a generally annular first-stage volute surrounding the first-stage impeller for receiving air discharged therefrom, a generally annular second-stage volute surrounding the second-stage impeller for receiving air discharged therefrom, and an outlet conduit connected to the second-stage volute and extending generally tangentially outward therefrom; and the compressor housing defining two separate passages connecting the first-stage volute to the second-stage inlet, each of the passages extending radially outward of the second-stage volute.