Application of high energy ignition systems to engines

Spark ignition engines are critically dependent on repeatable, reliable ignition to produce good performance and low pollutant emissions. Pollutant regulations and available three-way catalytic converter control technology determine that most engines are run with a nearly stoichiometric mixture. For stoichiometric gasoline-air engines, current transistor-switched coil spark discharge systems provide adequate ignition energy and are very reliable. However, lean burning engines are desirable for their better fuel economy. New catalytic converter technology may allow development of lean burning, high compression ratio engines which meet tight emission standards while providing better fuel economy. However, lean mixture engines (phi < 0.7) generally require much higher ignition energy to ensure reliable ignition. Other engine developments requiring high energy ignition systems include natural gas engines and cold-starting applications of diesel and methanol fuelled engines. This paper reviews progress on alternative ignition systems that supply higher energy sparks and sparks where the energy is more efficiently transferred to the gas mixture. Recent developments and demonstrations include high energy breakdown ignition systems, plasma jet igniters, and rail igniters. In addition, progress towards distributed ignition through prompt exhaust gas recirculation or prechamber torch,jet ignitions is covered. (C) 1997 Elsevier Science Ltd.