噴射パターンの幅広い制御を伴うディーゼルPCCI燃焼の性能と排気

Abstract

In order to search an injection strategy for partially PCCI combustion implementing low NOx, low smoke, and low maximum pressure rise rate, a series of experiment was carried out using a single-cylinder diesel engine equipped with a dual injector system (DIS), which includes two sets of common-rail injection system. The DIS enables variable injection rate for each injection pulse and a wide-range dwell between injection pulses, including even negative injection dwell. The baseline injection strategy was three-stage equally divided injection. The effects of injection timings, ratio of injection quantities, and second-injection pressure were investigated under a condition of constant speed, constant load, and constant NOx emission concentration. The results show that significant reduction of smoke emission was obtained by using the three-stage equally divided injection, while maximum pressure rise rate increased. A combination of increasing second-injection quantity, reducing third-injection quantity, and lowered second-injection pressure reduced the maximum pressure rise rate, keeping thermal efficiency and low smoke emission.