Abstract: The invention relates to a compressor provided with an impeller having a rotating shaft for the purpose of compressing air, and an air inlet having a circular cross-section centered on the rotating shaft so as to provide air for the impeller. Further provided are a plurality of movable vanes respectively pivoted in the inlet near the outer circumference of the circular cross-section, a mechanism for tilting these vanes, and a mechanism for causing a specific movable vane to project further downstream than the other movable vanes. When a circular flow is set up in the air inlet by the movable vanes, Karman vortices are produced from the rear ends of the vanes, and when the phases of these vortices combine together, noise is generated. A specific movable vane, the rear end of which projects further downstream than those of the other vanes, disrupts and interferes with the phase combination of the Karman vortices produced by the other vanes, and thereby prevents noise.

Abstract: A shaft seal arrangement of a turbocharger for an internal combustion engine having a throttle valve disposed upstream of a compressor of the turbocharger. The shaft seal arrangement is comprised of first and second seal rings fitted on a cylindrical thrust spacer mounted on a rotatable shaft on which turbine and compresser wheels are mounted. The first and second rings are located spaced from each other and positioned between the compressor and bearings for the rotatable shaft. An annular air chamber is formed between the first and second seal rings and supplied with atmospheric air through an air supply passage.