利用内部高温残余废气加热新鲜充量是实现均质压燃(HCCI)的一种有效方式。设计了几种具有小持续角的特殊进、排气凸轮轴,以满足高内部残余废气率。在Ricardo Hydra 140单缸汽油机上,分别采用不同持续角的凸轮轴研究了进、排气门定时和升程等参数对汽油机HCCI燃烧的影响。试验结果表明,排气门定时对残余废气率和HCCI燃烧有着更强的控制作用。选择合适的气门升程可以拓展HCCI运行范围,升程大的凸轮轴将HCCI运行范围向高速大负荷方向拓展,而升程小的凸轮轴则有利于获得更低的HCCI运行负荷和转速。
Heating fresh intake charge by internal high temperature residual gases is an effective and feasible way to realize gasoline fuel HCCI combustion. Two kinds of camshafts with short duration angle and small lift cam profile were designed to meet the high residual gas rate. The effects of intake valve and exhaust valve's phasing and lifting on HCCI combustion were investigated in a Ricardo's gasoline engine. Experimental results showed that the exhaust valve closing timing has a strong influence on the residual gas rate and HCCI combustion compared to intake valve opening timing. The results also showed an influence of the valve's lift on HCCI operation region. A camshaft with high lift can extend HCCI to the high-load and/or high-speed operation regions, and a camshaft with low lift is favorable to extend HCCI to the lowdoad and/ or low-speed operation regions.