Improvement on Energy Efficiency of the Spark Ignition System

Future clean combustion engines tend to increase the cylinder charge to achieve better fuel economy and lower exhaust emissions. The increase of the cylinder charge is often associated with either excessive air admission or exhaust gas recirculation, which leads to unfavorable ignition conditions at the ignition point. Advanced ignition methods and systems have progressed rapidly in recent years in order to suffice the current and future engine development, and a simple increase of energy of the inductive ignition system does not often provide the desired results from a cost-benefit point of view. Proper design of the ignition system circuit is required to achieve certain spark performances. In this paper, inductive coils with different primary and secondary inductances as well as turning ratios were tested to investigate the effect of inductive ignition system parameters on spark discharge characteristics under different control parameter such as charging voltage and charging duration. Based on the results from the electrical measurement, a simplified circuit model was then employed to perform a systematic study in order to improve the performance of the inductive ignition system. Furthermore, different ignition strategies based on inductive coil system including multi-coil discharge strategy, repetitive discharge strategy and dual coil discharge strategy were studied, and energy transfer efficiency was compared with traditional single spark strategy. Special attention was paid to energy losses inside the electrical path of the ignition system, and energy transfer efficiency from the primary coil to the spark gap was analyzed.