Patent ID: 7540149

Claim:
A compressor in an exhaust gas turbo-charger for an internal combustion engine, including a compressor wheel ( 8 ) which is rotatably mounted in a compressor inlet duct ( 19 ) of the compressor ( 5 ) having a duct wall ( 30 ) defining a semi-axial inlet flow path to the compressor wheel ( 8 ), an exhaust gas turbine ( 3 ) with a turbine wheel for transmitting rotation between the turbine wheel and the compressor wheel ( 8 ) via a shaft ( 9 ) and an auxiliary turbine rotor wheel ( 10 ) rotatably supported upstream of, and coaxially with, the compressor wheel ( 8 ), the auxiliary turbine rotor wheel ( 8 ) being driven by intake air during low power engine operation and connectable to the compressor wheel ( 8 ), the auxiliary turbine rotor wheel ( 10 ) includes a guide vane structure ( 21 ) mounted on a contoured ring ( 22 ) arranged in an inlet flow passage for the auxiliary turbine rotor wheel ( 10 ), the auxiliary turbine rotor wheel ( 10 ) being axially adjustable between a coupled position with the compressor wheel ( 8 ) and a decoupled position where axial adjustment of the auxiliary turbine rotor wheel ( 10 ) varies the effective flow cross-section; wherein, in the coupled position, the compressor wheel ( 8 ) and the auxiliary rotor wheel ( 10 ) are rotationally connected without contact by means of a magnetic clutch ( 26 ) for driving the compressor wheel ( 8 ) and the auxiliary turbine rotor wheel ( 10 ) is moved into contact with the duct wall ( 30 ), thereby closing the semi-axial flow path to the compressor wheel ( 8 ) and directing the inlet flow to the compressor wheel ( 8 ) through the auxiliary turbine rotor wheel ( 10 ); and, in the decoupled position, the auxiliary turbine rotor wheel ( 10 ) is decoupled from the compressor wheel ( 8 ).