Laser Ignition in Internal Combustion Engines- a Novel Approach Based on Advanced Lasers

Abstract

Laser ignition with its many potential advantages in comparison to conventional spark plug ignition has been investigated in detail. As ignition source several, to a certain extent exclusive prototype ns, Q-switched Nd:YAG lasers were used. Experiments were performed in a constant volume, high pressure/temperature combustion chamber and with two gasoline research engines. On one engine a mechanical & thermal robust, passive Q-switched, diode pumped Nd:YAG laser combined with special optimized optics was mounted directly on the research engine. Despite the harsh environment on the engine, the laser ignition system was able to operate the engine more than 10 hours. It turned out that the laser can ignite far leaner mixtures than with the conventional spark plug which means a significant reduction of NOx. Further on, the ignition delay and combustion time is shorter and the coefficient of variation (COV) of the induced mean effective pressure (IMEP) is significantly smaller.