Research On The Influence Of Multi-Pulse Discharge To The HCCI Combustion Process

HCCI combustion (CAI) can reduce the fuel consumption and the emission of NOx in part of the gasoline engine operation range. The spark ignition can stabilize combustion process on the boundary of HCCI combustion and enlarge operation range further more. In this paper, we investigate the influence of discharge parameters to the HCCI combustion process with the multi-pulse spark-assisted. Also we investigate the feasibility of enhancing the quality of spark-assisted HCCI combustion and expanding the operating range.In this paper, we developed a multi-pulse ignition system which can ignite several times in every cycle. Both pulses times (most is five) and pulses interval are changeable.Engine testing show: in the region of low load boundary that CAI cannot work, we can reliably control the process of the HCCI combustion and expand the low load range with the multi-pulse spark-assisted. In the region of low load boundary that CAI can reliably work, the multi-pulse discharge can shorten the combustion duration and reduce COVimep and then enhance the IMEP and reduce the ISFC. The concentrated discharge is better than the certain interval multi-pulse discharge in the same energy. In the region that near the heavy load boundary, the maximum pressure and the maximum rates of pressure rise are increased by once spark-assisted. But we can mitigate the adverse impacts by the multi-pulse ignition system to the same as the unsupported HCCI. So it is better not to use the way of spark-assisted in this region. In the region of heavy load boundary that CAI cannot work (because of knocking), the interval multi-pulse discharge can reduce the maximum pressure and the maximum rates of pressure rise, effectively suppress the trend of knocking. The heavy load boundary is expanded.