Abstract
A newly developed small-sized IES (inductive energy storage) circuit with a semiconductor switch at turn-off action was successfully applied to an ignition system. This IES circuit can generate repetitive nanosecond pulse discharges. An ignition system using repetitive nanosecond pulse discharges was investigated as an alternative to conventional spark ignition systems in the previous paper(1)(2). The ignition system using repetitive nanosecond pulse discharges was found to improve the inflammability of lean combustible mixtures, such as extended flammability limits, shorted ignition delay time, with increasing the number of pulses. In this paper, we examined the ignition characteristics under diluted condition considering EGR. In addition, the authors sought for the mechanisms for improving the inflammability in more detail using conventional ignition plug. Moreover, an application of this ignition system to a SI engine was conducted and the diluted limit was investigated. The result shows that the diluted limit is extended from 17.5 % to 22.5 % in EGR ratio and that thermal efficiency is improved by 5% by replacing the ignition system from a conventional one.
