Patent ID: 7334562

Claim:
A method of operating an internal combustion engine having a combustion chamber with a piston, the internal combustion engine capable of injecting fuel into the combustion chamber multiple times during a cycle, the method comprising: performing a first fuel injection after approximately −25 crank angle degrees after top dead center and before approximately 15 crank angle degrees after top dead center; performing a second fuel injection at least 5 degrees after the start of the first fuel injection and less than approximately 25 crank angle degrees after the start of the first fuel injection; adjusting an amount of the second fuel injection relative to an amount of the first fuel injection as a level of noise generated by the engine varies; recirculating at least a portion of the exhaust gas produced by the engine, back into the combustion chamber via a recirculated exhaust gas cooler; and varying a level of cooling provided to the recirculated exhaust gas by the cooler responsive to the amount of the second fuel injection.