Patent ID: 7229243

Claim:
A compressor for compressing a gas, the compressor comprising: a housing defining an inlet and an outlet; an impeller wheel including a plurality of vanes rotatably mounted within the housing; the housing having an inner wall defining a surface located in close proximity to radially outer edges of impeller vanes which sweep across said surface as the impeller wheel rotates about its axis; wherein the inlet comprises: an outer tubular wall extending away from the impeller wheel in an upstream direction and forming a gas intake portion of the inlet; an inner tubular wall having an internal diameter D extending away from the impeller wheel in an upstream direction within the outer tubular wall and defining an inducer portion of the inlet; an annular gas flow passage defined between the inner and outer tubular walls and having an upstream end and a downstream end separated by a length L 1 measured along an annular gas flow passage axis, the upstream end of the annular passage communicating with the intake or inducer portions of the inlet through at least one upstream aperture; at least one downstream aperture communicating between a downstream portion of the annular flow passage and said surface of the housing swept by the impeller vanes; the inner tubular wall extending upstream of said at least one downstream aperture by a length L 2 measured along the annular gas flow passage axis, said internal diameter D being constant along substantially the entire length L 2 of the inner tubular wall; wherein L 1 /D>0.65 and/or L 2 /D>0.6.