Abstract: A method for controlling an inlet-adjustment mechanism in an air inlet for a compressor so as to switch the mechanism in a binary fashion between two positions P1 and P2 for adjusting a flow area of the inlet. The method includes identifying a threshold line on a compressor map of pressure ratio versus corrected flow rate for the compressor. The threshold line is a line on which the pressure ratio and flow rate of the compressor are the same for the P1 and P2 positions of the inlet-adjustment mechanism at equal speeds. When the operating point of the compressor on the compressor map crosses the threshold line, the inlet-adjustment mechanism is switched from one of its binary positions to the other.

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: An assembly can include a compressor housing, an adjustable wall disposed within the compressor housing that defines an air inlet to an inducer portion of a compressor wheel, and an adjustment mechanism to adjust the wall and thereby adjust at least a diameter of the air inlet. Various other examples of devices, assemblies, systems, methods, etc., are also disclosed.

Abstract: A method for controlling an inlet-adjustment mechanism in an air inlet for a compressor so as to switch the mechanism in a binary fashion between two positions P1 and P2 for adjusting a flow area of the inlet. The method includes identifying a threshold line on a compressor map of pressure ratio versus corrected flow rate for the compressor. The threshold line is a line on which the pressure ratio and flow rate of the compressor are the same for the P1 and P2 positions of the inlet-adjustment mechanism at equal speeds. When the operating point of the compressor on the compressor map crosses the threshold line, the inlet-adjustment mechanism is switched from one of its binary positions to the other.

Abstract: A statorless axial turbine for a turbocharger has a turbine housing assembly defining a meridionally divided scroll extending circumferentially and surrounding the turbine wheel, the meridionally divided scroll defining a first scroll extending substantially fully about the turbine wheel and a separate second scroll extending substantially fully about the turbine wheel. The turbine housing assembly defines a separate inlet for each of the first and second scrolls through which a separate exhaust gas stream is received, and separate first and second outlets for each of the first and second scrolls, respectively, through which the respective exhaust gas streams are fed into an inlet side of the turbine wheel generally in an axial direction of the turbine wheel.

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: A statorless or nozzleless axial turbine for a turbocharger has an axial turbine wheel that receives a swirling flow of exhaust gas substantially in an axial direction. The turbine includes a sector-divided turbine housing defining a plurality of separate exhaust gas inlets each for receiving a separate exhaust gas stream from an internal combustion engine, the sector-divided turbine housing further defining a plurality of separate angular sector passageways each of which occupies a fractional part of a circumference surrounding the turbine wheel, each angular sector passageway being supplied with exhaust gas by a respective one of the plurality of exhaust gas inlets. The turbine housing assembly defines a separate sector outlet for each angular sector passageway. The turbine housing assembly can include a separately formed heat shroud, and the sector outlets can be formed at least in part by the heat shroud.

Abstract: A radial-radial compressor includes an inlet-adjustment mechanism in an air inlet for the compressor, operable to move between an open position and a closed position in the air inlet. The inlet-adjustment mechanism includes a tubular sleeve that is movable in the air inlet with an axial component of movement for adjusting a spacing distance of a trailing edge of the sleeve from an inducer portion of the wheel. In an “on” position the spacing distance is relatively greater, while in the “off” position the spacing distance is relatively smaller and the sleeve therefore reduces an effective inlet area into the inducer portion of the wheel, relative to the effective inlet area in the “on” position.

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 two-sided turbocharger compressor wheel and a housing forming a diffuser for the compressor. A first side and a second side of the compressor wheel are characterized by different values of a trim and of an annulus area. A first side of the diffuser surrounds the first side of the compressor wheel, and a second side of the diffuser surrounds the second side of the compressor wheel. The first and second sides of the diffuser are characterized by different annulus area ratios. The blades of the first and second sides of the compressor wheel are angularly offset from one another. The compressor wheel is configured for greater flow through the side of the compressor wheel that faces away from a related turbine wheel.

Abstract: A two-sided turbocharger compressor wheel and a housing forming a diffuser for the compressor. A first side and a second side of the compressor wheel are characterized by different values of a trim and of an annulus area. A first side of the diffuser surrounds the first side of the compressor wheel, and a second side of the diffuser surrounds the second side of the compressor wheel. The first and second sides of the diffuser are characterized by different annulus area ratios. The blades of the first and second sides of the compressor wheel are angularly offset from one another. The compressor wheel is configured for greater flow through the side of the compressor wheel that faces away from a related turbine wheel.

Abstract: An assembly can include a compressor housing, an adjustable wall disposed within the compressor housing that defines an air inlet to an inducer portion of a compressor wheel, and an adjustment mechanism to adjust the wall and thereby adjust at least a diameter of the air inlet. Various other examples of devices, assemblies, systems, methods, etc., are also disclosed.

Abstract: A statorless axial turbine for a turbocharger has a turbine housing assembly defining a meridionally divided scroll extending circumferentially and surrounding the turbine wheel, the meridionally divided scroll defining a first scroll extending substantially fully about the turbine wheel and a separate second scroll extending substantially fully about the turbine wheel. The turbine housing assembly defines a separate inlet for each of the first and second scrolls through which a separate exhaust gas stream is received, and separate first and second outlets for each of the first and second scrolls, respectively, through which the respective exhaust gas streams are fed into an inlet side of the turbine wheel generally in an axial direction of the turbine wheel.

Abstract: A statorless or nozzleless axial turbine for a turbocharger has an axial turbine wheel that receives a swirling flow of exhaust gas substantially in an axial direction. The turbine includes a sector-divided turbine housing defining a plurality of separate exhaust gas inlets each for receiving a separate exhaust gas stream from an internal combustion engine, the sector-divided turbine housing further defining a plurality of separate angular sector passageways each of which occupies a fractional part of a circumference surrounding the turbine wheel, each angular sector passageway being supplied with exhaust gas by a respective one of the plurality of exhaust gas inlets. The turbine housing assembly defines a separate sector outlet for each angular sector passageway. The turbine housing assembly can include a separately formed heat shroud, and the sector outlets can be formed at least in part by the heat shroud.

Abstract: A turbocharger including a turbine wheel having a hub-to-tip ratio of no more than 60% and blades with a high turning angle, a turbine housing forming an inwardly spiraling primary-scroll passageway that significantly converges to produce highly accelerated airflow into the turbine at high circumferential angles, and a two-sided parallel compressor. The compressor and turbine each produce substantially no axial force, allowing the use of minimal axial thrust bearings.

Abstract: A turbocharger including a turbine wheel having a hub-to-tip ratio of no more than 60% and blades with a high turning angle, a turbine housing forming an inwardly spiraling primary-scroll passageway that significantly converges to produce highly accelerated airflow into the turbine at high circumferential angles, and a two-sided parallel compressor. The compressor and turbine each produce substantially no axial force, allowing the use of minimal axial thrust bearings.