Patent ID: 7083379

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 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; at least one downstream aperture communicating between a downstream portion of the annular gas flow passage and said surface of the housing swept by the impeller vanes; at least one upstream aperture communicating between an upstream portion of the annular flow passage and the inducer or intake portions of the inlet; and a plurality of inlet guide vanes mounted within the inducer portion of the inlet downstream of said at least one upstream aperture to induce pre-swirl in gas flowing through the inducer portion of the inlet.