A Gasoline Fueled Pre-Chamber Jet Ignition Combustion System at Unthrottled Conditions 2012-01-0386

Turbulent Jet Ignition is an advanced spark-initiated pre-chamber combustion system for otherwise standard spark ignition engines. Combustion in the main chamber is initiated by jets of partially combusted (reacting) pre-chamber products which provide a high energy ignition source. The resultant widely distributed ignition sites allow relatively small flame travel distances enabling short combustion durations and high burn rates. Demonstrated benefits include ultra-lean operation (λ≻2) at part load and high-load knock improvement near stoichiometric conditions.

Although previous results of this combustion system have been very promising, the main hurdle of this system has been the need for a dual-fuel system, with liquid gasoline used in the main combustion chamber and small fractions of gaseous propane in the pre-chamber. The purpose of this paper is to demonstrate that this combustion system can operate robustly using a sole gasoline system, with vaporized gasoline found to be a successful substitute for the pre-chamber propane over all comparable conditions. With this concept, the test engine recorded a peak net thermal efficiency of 42.8% (190 g/kWh ISFCn) and single-digit engine-out NOx emissions. The pre-chamber jet ignition system was also examined at unthrottled stoichiometric conditions up to 5500 rev/min, with successful operation demonstrated up to 13.2 bar IMEPn. Additionally, jet ignition combustion was also examined in order to evaluate pressure rise rate limitations for potential future high-load powertrain applications.