Patent ID: 7594398

Claim:
An internal combustion engine comprising: a crankcase that includes a plurality of cylinders; an exhaust system in fluid communication with the plurality of cylinders, wherein the exhaust system includes a turbine in operable association with a compressor; an intake system in fluid communication with the plurality of cylinders and the compressor; a first exhaust gas recirculation (EGR) cooler in fluid communication with the exhaust system through an inlet passage that is connected to the exhaust system between the plurality of cylinders and the turbine; a second EGR cooler in fluid communication with the intake system through an outlet passage that is connected to the intake system between the plurality of cylinders and the compressor, wherein the second EGR cooler is in fluid communication with the first EGR cooler, and wherein the second EGR cooler is connected to the first EGR cooler in a series configuration; a transfer passage disposed between the first EGR cooler and the second EGR cooler; an EGR valve, disposed within the transfer passage, having a predetermined maximum temperature limit, that is arranged and constructed to control a flow of fluid through the transfer passage while the internal combustion engine operates; and wherein the first EGR cooler cools the flow of exhaust passing through it from a first temperature that exceeds the condensation temperature of the exhaust and the maximum temperature limit for the EGR valve to a second temperature that still exceeds the condensation temperature of the exhaust but not the maximum temperature limit for the EGR valve as the exhaust passes through the transfer passage, and the second EGR cooler further cools the exhaust passing through it to a third temperature within a range that includes the condensation temperature of the exhaust.