Abstract: A compression ignition engine comprising at least one combustion chamber, an air intake system, a fuel system, an exhaust system and an exhaust gas recirculation system. The air intake system conveys air to the chamber. The exhaust system conveys exhaust gases from the combustion chamber. The exhaust gas recirculation system is capable of recirculating a portion of the exhaust gases into air intake system. The exhaust gas recirculation system comprises a cooler package and a valve. The valve controls the amount of air flow through the cooler package. The cooler package includes a first portion, a second portion and a control valve. The control valve of the cooler package is configured to control whether the air that flows through the cooler package flows only through one of the first or the second portion or through both of the first portion and the second portion in parallel.

Abstract: A preferred embodiment EGR valve permits exhaust gas to be induced into the intake line downstream of the compressor, while minimizing the need to reduce the size of the turbocharger. The preferred embodiment EGR valve exploits variations around the mean pressure in the EGR passage created by the engine cycle by selectively opening when the pressure in the EGR valve exceeds the pressure in the intake line. Thus, exhaust gas is recirculated even when the engine is running near torque peak. The preferred embodiment EGR valve also exploits the higher mean pressure in the exhaust line relative to the intake line at higher engine speeds by remaining open, in order to minimize the energy consumed in opening and closing the EGR valve.