Patent ID: 7137379

Claim:
A method for controlling fuel injection to provide a rich combustion mixture for periodically regenerating a lean NO X trap disposed in the exhaust system of a diesel engine in which exhaust gas is recirculated and fuel is injected by pilot and main injections during each combustion cycle, said method comprising: sensing engine speed; sensing an operating parameter correlative of engine load; providing a map of the engine operating regime; delimiting a region of the engine operating regime in which low temperature combustion is desired to provide a fuel rich combustion mixture; increasing exhaust gas recirculation when the engine is operating in said delimited region; reducing intake air when the engine is operating in said delimited region; increasing the volume of fuel injected during the main fuel injection of the combustion cycle when the engine is operating in said delimited region; advancing the timing of fuel injected during main fuel injection when the engine is operating in said delimited region; decreasing exhaust gas recirculation when the engine is operating outside of said delimited region; reducing intake air when the engine is operating outside of said delimited region; increasing the volume of fuel injected during main fuel injection when the engine is operating outside of said delimited region; and, retarding the timing of fuel injected during main fuel injection when the engine is operating outside of said delimited region.