Abstract: A liquid primary fuel is ignited by HCCI with the assistance of the early injection of a liquid pilot fuel. Pilot fuel injection and/or ignition are preferably controlled so as to permit the injected pilot fuel to become thoroughly distributed through and mixed with the primary fuel/air charge in the combustion chamber and vaporized prior to ignition. Pilot fuel having a lower autoignition temperature will be ignited by compression ignition, followed by the ignition of the homogeneous mixture of the primary fuel and air. HCCI combustion of the primary fuel is facilitated by 1) selection of the properties of the primary and pilot fuels and 2) obtaining a homogenous mixture of primary fuel and air by injecting primary fuel into the engine's intake air stream in the form of finely atomized droplets having a mean diameter in the micron range.

Abstract: An EGR equipped internal combustion engine is controlled to maximize the beneficial effects and minimize the detrimental effects of EGR on engine operation. Specifically, at least one parameter indicative of the O2 concentration in the intake mixture and/or at least one parameter indicative of the H2O concentration in the intake mixture is monitored, and the monitored parameter is relied on to control one or more aspects of engine operation by open loop adjustment of other control strategies and/or by a separate closed loop control strategy. These controls are applicable to virtually any engine, and are particularly beneficial to lean burn engines such as diesel (compression ignition) engines, spark ignited natural gas engines, and dual fuel or other compression ignited natural gas engines. The engine may be equipped with either actively controllable EGR or passive and uncontrolled EGR.

Abstract: A liquid primary fuel is ignited by HCCI with the assistance of the early injection of a liquid pilot fuel. Pilot fuel injection and/or ignition are preferably controlled so as to permit the injected pilot fuel to become thoroughly distributed through and mixed with the primary fuel/air charge in the combustion chamber and vaporized prior to ignition. Pilot fuel having a lower autoignition temperature will be ignited by compression ignition, followed by the ignition of the homogeneous mixture of the primary fuel and air. HCCI combustion of the primary fuel is facilitated by 1) selection of the properties of the primary and pilot fuels and 2) obtaining a homogenous mixture of primary fuel and air by injecting primary fuel into the engine's intake air stream in the form of finely atomized droplets having a mean diameter in the micron range.