Radio Frequency Ignition System for Gasoline Direct Injection Engines
G. Bachmaier1, R. Baumgartner1, D. Evers1, R. Freitag1, Th. Hammer2, G. Lins2
1Siemens AG, Corporate Research and Technologies, Munich, Germany
2Siemens AG, Corporate Research and Technologies, Erlangen, Germany
Abstract— The application of pulsed rf-plasma systems for the ignition of high pressure gasoline direct injection engines was investigated in laboratory experiments performed in a high pressure test cell. The design of plasma actuator and pulsed power electronics was assisted by numerical modeling and simulation. Gas discharge breakdown simulation provided relations between electrode gap, pressure and voltage amplitude required for plasma initiation in air. Thermal equilibrium simulations resulted in a first guess of rf-power and pulse duration required for reliable ignition of a fuel-air mixture. Three generations of rf-plasma igniters were characterized with respect to plasma impedance, volume and temperature by means of imaging and spectroscopy. A spiker-sustainer design utilizing separate electrical circuits for plasma initiation and boosting the plasma power had the best performance. In single cylinder engine testing improved performance regarding ignition reliability, engine efficiency, and emissions was demonstrated for cylinder pressures up 2.5 MPa.
Keywords— rf-plasma, high pressure gasoline direct injection engine, ignition, gas discharge breakdown