Abstract: A multi-stage compressor for a turbocharger includes a compressor housing that defines an aperture for receiving a compressor wheel for successively compressing air in first and second stages. First- and second-stage inlets are fluidly connected to the aperture in opposite 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. First and second passages fluidly connect the first-stage volute to the second-stage inlet. The passages approach the second-stage inlet from opposite radially inward directions, and are asymmetric with respect to any pair of orthogonal axes having an origin lying on the turbocharger rotary axis as viewed on a transverse cross-section that is normal to the turbocharger axis.

Abstract: A multi-stage compressor for a turbocharger includes a compressor housing that defines an aperture for receiving a compressor wheel for successively compressing air in first and second stages. First- and second-stage inlets are fluidly connected to the aperture in opposite 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. First and second passages fluidly connect the first-stage volute to the second-stage inlet. The passages approach the second-stage inlet from opposite radially inward directions, and are asymmetric with respect to any pair of orthogonal axes having an origin lying on the turbocharger rotary axis as viewed on a transverse cross-section that is normal to the turbocharger axis.

Abstract: A turbocharger includes a two-stage serial compressor having first and second impellers, with a crossover duct for leading air from the first impeller into the second impeller for further compression. The compressor housing also defines a bypass duct from the crossover duct to the air discharge duct from the compressor, and a bypass valve disposed in the bypass duct. Under certain operating conditions (such as high-flow, low-pressure-ratio conditions) the bypass valve can be opened to bypass the second impeller, such that the compressor behaves like a single-stage compressor. At other operating conditions, the bypass valve is closed so that the compressor provides two-stage compression for higher pressure ratios.

Abstract: An assembly can include a first radial compressor wheel that has a rotational axis and that includes a hub surface that includes an annular ridge disposed at a radius measured from the rotational axis; a second radial compressor wheel that includes a hub surface; and an annular baffle disposed at least in part between the hub surfaces where the annular baffle includes an outer surface and an inner edge that defines an opening having a central axis where the outer surface includes a surface portion to one side of the inner edge that faces the hub surface of the first radial compressor wheel, where the surface portion includes an annular channel over a radial width measured from the central axis and where the radial width spans the radius of the annular ridge.

Abstract: A turbocharger includes a two-stage serial compressor having first and second impellers, with a crossover duct for leading air from the first impeller into the second impeller for further compression. The compressor housing also defines a bypass duct from the crossover duct to the air discharge duct from the compressor, and a bypass valve disposed in the bypass duct. Under certain operating conditions (such as high-flow, low-pressure-ratio conditions) the bypass valve can be opened to bypass the second impeller, such that the compressor behaves like a single-stage compressor. At other operating conditions, the bypass valve is closed so that the compressor provides two-stage compression for higher pressure ratios.

Abstract: An assembly can include a first radial compressor wheel that has a rotational axis and that includes a hub surface that includes an annular ridge disposed at a radius measured from the rotational axis; a second radial compressor wheel that includes a hub surface; and an annular baffle disposed at least in part between the hub surfaces where the annular baffle includes an outer surface and an inner edge that defines an opening having a central axis where the outer surface includes a surface portion to one side of the inner edge that faces the hub surface of the first radial compressor wheel, where the surface portion includes an annular channel over a radial width measured from the central axis and where the radial width spans the radius of the annular ridge.