Patent ID: 7540150

Claim:
An internal combustion engine comprising a high pressure turbocharger ( 2 ) close to the engine ( 1 ) and a low pressure turbocharger ( 3 ) further remote from the engine ( 1 ), the high pressure turbocharger ( 2 ) having a high pressure turbine ( 4 ) and a high pressure compressor ( 5 ) connected to the high pressure turbine ( 4 ) so as to be driven thereby and the low pressure turbocharger ( 3 ) having a low pressure turbine ( 7 ) and a low pressure compressor ( 8 ) connected to the low pressure turbine ( 7 ) to be driven thereby, an intake line ( 12 ) extending from the low pressure compressor ( 8 ) via the high pressure compressor ( 5 ) to the engine for supplying pressurized combustion air thereto, said internal combustion engine being divided into first and second sections ( 1 a, 1 b ), a first exhaust gas line ( 10 ) extending from the first section ( 1 a ) of the engine ( 1 ) via the high pressure turbine ( 4 ) to a first section ( 7 a ) of the low pressure turbine ( 7 ) which first section ( 7 a ) is provided with a variable turbine geometry ( 22 ) for controlling the pressure in the first exhaust gas line ( 10 ) and a second exhaust gas line ( 11 ) extending from the second section ( 1 b ) of the engine ( 1 ) directly to a second section ( 7 b ) of the low pressure exhaust turbine ( 7 ) providing for a low backpressure in the second exhaust gas line ( 11 ) of the second engine section ( 1 b ), and an exhaust gas recirculation line ( 16 ) branching off the first exhaust gas line ( 10 ) upstream of the high pressure turbine ( 4 ) and extending to the intake line ( 12 ) downstream of the high pressure compressor ( 5 ) for recirculating exhaust gas from the first section ( 1 a ) of the engine to the pressurized combustion air supplied to the engine ( 1 ) under a pressure. controllable by the variable turbine geometry ( 22 ) of the low pressure turbine ( 7 ).