A Study of an Energetically Enhanced Plasma Ignition System for Internal Combustion Engines

The effects of a plasma enhanced ignition system on the performance of a small, single cylinder, and four-stroke gasoline engine are examined. Dynamometer testing of the 33.5- cm³ engine at various operating speeds was performed with both the engine´s stock coil ignition system and a radio frequency (RF) plasma ignition system. The RF system is designed to provide a quasi-nonequilibrium plasma discharge that features a high voltage pulsar that provides 400 mJ of energy for each discharge and voltages of up to 30 kV. Tests show improvement of the engine´s combustion stability at all operating conditions and the extension of the engine´s lean flammability limit with the RF system. Particular attention is given to the improvements that the RF system provides while burning lean air fuel mixtures. In addition, gas analysis of the 33.5- cm³ engine´s exhaust and high speed images of the RF system taken in a separate 0.4-L optical engine are also presented.