Patent ID: 7013879

Claim:
An exhaust gas recirculation (EGR) system comprising: an engine having an intake manifold and an exhaust manifold; a turbocharger with at least one compressor stage; a first exhaust gas bypass stream connected to receive exhaust gas upstream of the turbocharger; a first control valve connected in the first exhaust gas bypass stream to control the amount of exhaust gas received from the exhaust manifold; a second exhaust gas bypass stream connected to receive exhaust gas exiting the exhaust manifold through a turbine section of the turbocharger and combine the gas with an intake air stream to form an exhaust gas/air mixture that is directed into a first compressor stage of the turbocharger; a second control valve connected within the second exhaust gas bypass stream upstream of a connection point with the intake air stream for controlling a relative amount of air and exhaust gas in the exhaust gas/air mixture routed to the first compressor stage of the turbocharger; a second turbocharger operated in parallel with the turbocharger; a bypass for directing a partial flow of exhaust exiting the exhaust manifold into an inlet of a turbine section of the second turbocharger and a first synchronized control valve to control said partial flow; and a second synchronized control valve to control a relative amount of exhaust gas/air mixture entering compressor sections of the turbochargers; wherein exhaust gas exiting the turbine section of the second turbocharger forms a part of the second exhaust gas bypass stream and the pressurized exhaust gas/air mixture exiting the compressor sections of the turbochargers is combined with the first exhaust gas bypass stream before being introduced into the intake manifold.