气门正时对柴油燃料HCCI燃烧影响的初步实验研究

Initial Experimental Study on the Influence of Valve Timing on Diesel-Fueled HCCI

开发了变进排气正时控制机构,实现气门正时的调节.采用在进气上止点前进行柴油燃料的喷射,利用缸内残余高温废气余热加速燃油蒸发,实现了柴油燃料的HCC I燃烧.同时,研究了不同气门重叠期下HCC I燃烧的燃烧特性,不同负荷的工作稳定性和排放特性.结果表明,对于低温自燃性好的柴油燃料,排气门早关和进气门晚开引起的缸内温度升高比由此引起的残余废气增加对工质的稀释效果更大,使HCC I燃烧的着火始点提前,易引起大负荷工况HCC I燃烧的工作粗暴,但有利于小负荷工况HCC I燃烧的工作稳定性.

The designed VVT （variable valve timing） system can change the valve timing in running condition. Diesel-fueled homogeneous charge compression ignition （HCCI） is achieved by direct fuel injection before TDC of intake stroke. The residual gas in the cylinder of high temperature facilitates fuel vaporization and mixing. The combustion performance, operation stability at high and low load limits. The emission performance were studied at different negative valve overlaps. The results show that with easy self-ignition for the diesel fuel, the temperature rise effect of residual gas is more dominating than the dilution effect. The increase of negative valve overlap advance the start of combustion, and easily roughen HCCI combustion at high load, but benefits the operation stability at low load.