Importance

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Abstract

Pilot fuel injection and/or ignition are controlled in a pilot ignited, gas-fueled, compression ignition engine so as to maintain a relationship Dp/Di of <1, where Dp is the duration of the pilot injection event and Di is the ignition delay period as measured from the start of initiation of pilot fuel injection (Tp) to the start of pilot fuel autoignition (Ti). Dp/Di is less than 1 when a mixing period Dm exists between the end of pilot fuel injection and the start of autoignition. This mixing period permits the injected pilot fuel to become thoroughly distributed through and mixed with the gaseous fuel/air charge in the combustion chamber and vaporized prior to ignition, resulting in improved premixed burning of a heterogeneous mixture of the pilot fuel, the gaseous fuel, and air and dramatically reduced NOx emissions. Dp/Di (or a characteristic of it such as Di or Dm) preferably is maintained within a predetermined range on a cycle-by-cycle, full speed and load range basis so as to maximize ignition intensity under all engine operating condition. The resultant maximization of pilot ignition intensity can generate instantaneous power on the order of 200 kW/l of engine displacement.

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First Claim