Diesel engine exhaust gas recirculation (EGR) system and method

Apparatus for and method of exhaust gas recirculation in an internal combustion engine that operates with charge air boost. An EGR valve has an inlet port communicated to the engine exhaust system upstream of a throttle valve in the tailpipe and an outlet port communicated to the engine intake system. The throttle valve is controlled to selectively restrict exhaust gas flow through the tailpipe so as to maintain the difference between pressure at the EGR valve inlet and pressure at the EGR valve outlet substantially unaffected by changes in pressure in the intake system and in the exhaust system. The invention is particularly suited for a turbocharged diesel engine.