利用预喷射降低柴油机低速全负荷黑烟排放

Study on Decreasing Smoke Emission of Diesel Engine under Low-Speed Full-Load Conditions by Using Pilot Injection

针对一台产品电控柴油机,分析了其低速全负荷工况下黑烟产生的原因,并针对黑烟产生的原理进行了降低其黑烟排放的研究工作,采用了增加喷射压力、改变喷油定时和采用预喷射等一系列方法。其中利用预喷射形成预混合燃烧降低了柴油机低速全负荷排气烟度,经过分析和试验达到了预期的效果。研究结果表明,部分预喷射柴油的充分蒸发和混合减少了产生黑烟的富混合气区域,同时,少量预喷射燃油的提前放热减少了主喷射燃烧时的温度梯度,这些因素都有效地减少了柴油机黑烟排放。但与优化的无预喷射方式相比,预喷射方式的燃油消耗略有升高。

In this paper, the reason of smoke emission of an electronically controlled diesel engine under low-speed full-load conditions was analyzed. The research work for reducing engine＇ s smoke emission have been conducted such as increasing injection pressure, changing injection timing, pilot injection etc. Among those methods, the pilot injection can produce the premixed charge combustion and give a satisfactory result on decreasing smoke emission of the diesel engine at low-speed full-load. The results show that the improvement in vaporization and mixing by using pilot injection can decrease the rich fuel area that is regarded to form the smoke. Meanwhile, early heat release of the pilot fuel reduces the temperature gradient during main combustion stage and decreases smoke emission. However, Comparing with the injection without pilot, fuel consumption shows a slight increase in the case of pilot injection.