2009 Volume 40 Issue 5 Pages 1223-1228
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). Experiments were conducted using spherically expanding flame condiguration for CH4 and C3H8-air mixtures under various conditions. 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, the authors seek for the mechanisms for improving the inflammability in more detail to optimize the ignition system for a real engine use. Moreover, an application of this ignition system to a SI engine was conducted. As a result, the lean limit was extended from 20 to 23 in A/F at IMEP 440kPa by replacing the ignition system from a conventional one, and indicated thermal efficiency was improved by 11%.
