Patent ID: 8172525

Claim:
A centrifugal compressor, comprising: a stationary housing; and an impeller of the compressor, the impeller being supported rotationally in the housing, the housing having an inlet passage of diameter larger than that of an annular inlet area of the impeller including a plurality of radially outwardly directed blades thereon, each blade including a leading edge, a trailing edge, and an outer tip, a plurality of slots being formed in a peripheral part of the inlet passage of the housing near the annular inlet area of the impeller between an annular ring supported by a plurality of struts extending axially inwardly from a surface of the peripheral part such that the plurality of slots are partitioned by the struts and arranged circumferentially concentrically with the center of rotation axis of the impeller, an end of each of the slots being opened to the inlet passage at the peripheral part thereof and the other end being open to gas flow space of the impeller at the outer tip near the leading edge via an annular slit behind the annular ring part, wherein four or more struts are provided to support the annular ring part such that all the struts except for only one strut are located at positions which are determined when all the struts are to be located at circumferentially equal spacing and said only one strut is located at a position shifted circumferentially from one of said equally spaced positions by a certain central angle.