NO to NO2 conversion control in a compression injection engine by hydrocarbon injection during the expansion stroke

摘要

The invention is directed towards a method for adjusting the NO2 to NO content of a diesel engine's exhaust without affecting engine performance. The NO2 to NO ratio is adjusted by varying the amount and tinting of secondary hydrocarbon injection during the engine's expansion stroke. The appropriate amount of secondary injected hydrocarbon and the appropriate injection timing are determined from calibration values obtained by direct engine measurements and the desired NO2:NO ratio.