Patent ID: 8307646

Claim:
An EGR system for an engine, the engine having an intake air manifold, an exhaust manifold, a turbocharger with an exhaust gas turbine that drives an intake air compressor, the exhaust gas manifold directing exhaust gas into the exhaust gas turbine and the intake air compressor directing compressed air into the intake air manifold, comprising: a supplemental compressor mechanically connected to the exhaust gas turbine to be driven by the exhaust gas turbine, the supplemental compressor having a supplemental compressor inlet for receiving a portion of the exhaust gas flow rate from an outlet of the exhaust gas turbine, the supplemental compressor compressing the portion of the exhaust gas flow rate; a control valve in fluid communication between the outlet of the exhaust gas turbine and the supplemental compressor inlet for controlling the portion of the exhaust gas flow rate into the supplemental compressor; the supplemental compressor having a supplemental compressor wheel for compressing the portion of the exhaust gas flow rate; a throttle valve located downstream of the supplemental compressor wheel to control the portion of the exhaust gas flow rate; and a path between the throttle valve and the intake air manifold, wherein the supplemental compressor wheel comprises a centrifugal compressor wheel and the throttle valve comprises a circular cylindrical sleeve movable to selectively cover or expose outlets between vanes of the centrifugal compressor wheel.