Abstract: A turbocharger with a two-stage compressor having first- and second-stage impellers mounted on a common shaft in a back-to-back configuration. The first-stage impeller has a boreless configuration, defining an unthreaded pilot hole receiving an unthreaded end of the shaft so as to establish a coaxial relationship between the impeller and the shaft. The first impeller further defines a hollow cylindrical pilot member that projects from the back of the impeller and is received in a portion of the bore through the second-stage impeller to position the impellers coaxially with each other. The shaft passes through the pilot member and is externally threaded for engaging threads on the inner surface of the pilot member to secure the impellers to the shaft. The bore of the second impeller has a second portion that engages an outer cylindrical surface of the shaft to establish a coaxial relationship between the shaft and impeller.

Abstract: A two-stage radial compressor having a ported second-stage shroud, forming a passive surge control system. Thus, some proportion of the fluid is allowed to flow between the second-stage of the compressor in the vicinity of the impeller blade tips, through a port in the shroud into an upstream portion of the compressor flow path that leads into the second-stage impeller inlet. The fluid is allowed to flow in either direction, depending on the pressure difference existing between the two locations. Surge margin at higher pressure ratios is significantly increased by the ported second-stage shroud.

Abstract: A multi-stage compressor and associated compressor housing and method are provided. The housing defines an aperture for receiving a compressor wheel for successively compressing a gas in first and second stages. First- and second-stage inlets are fluidly connected to the aperture in generally axial directions, and first- and second-stage volutes extend at least partially annularly therearound so that each volute is configured to receive gas flowing generally radially outward from the compressor wheel. In addition, first and second passages fluidly connect the first-stage volute to the second-stage inlet. Each passage extends from the first-stage volute to a position radially outward of the second-stage volute and therefrom to the second-stage inlet at an axial position opposite the second-stage volute from the first-stage volute.

Abstract: Butterfly valves of this invention generally comprise a flapper element that is rotatably disposed within an annular bore of a valve housing. The valve may be configured to provide an improved degree of gas flow control sensitivity from a closed to a partially opened position through the use of projections that extend radially inwardly from the housing bore, are positioned at diametrically opposed positions within the bore, and that are specifically configured to provide a gradual increase in gas flow across the valve as the flapper is moved from a closed position to a partially opened position. The butterfly valve may be configured having further projections that extend radially inwardly a distance therein, that are positioned at diametrically opposed positions in the bore, and that include faces that are sized and shaped to cooperate with respective opposed surfaces of the flapper to seal off gas flow within the bore when the flapper is placed into a closed position.