Timing of the combustion event in an homogenous-charge compression-ignition engine is controlled by adjusting the reactivity of the fuel, or of the fuel/air mixture inducted into the combustion chamber of the engine, thereby providing a means of controlling the combustion phasing. When the mixture is made more reactive, combustion occurs earlier in the cycle, and when the mixture reactivity is decreased, the reaction phasing is retarded. In the present invention, the reactivity of the intake charge is regulated in one embodiment by using a catalytic reaction in the intake system to partially, oxidize the intake mixture. In another embodiment, fuel reactivity is adjusted by passing a portion of the fuel through a catalyst or a non-thermal plasma generator prior to injection into the engine. In still another illustrated embodiment, an additive is controllably added to the fuel prior to injection into the engine to increase or decrease fuel reactivity.
Rudolf H. Stanglmaier; Charles E. Roberts Jr.; Daniel W. Stewart