冷起动首循环瞬态HC排放与进气道燃料输运特性的关系

Transient HC Emissions and Fuel Transport in the Intake Port of the First Firing Cycle During Cold Start

从循环控制的角度,详细研究了液化石油气(LPG)点燃式发动机冷起动首循环瞬态HC排放和进气道燃料输运特性.研究结果表明,有一定比例的气态LPG燃料不能进入缸内,残留在进气道内.进气道残留的HC体积分数随首循环混合气空燃比的增加而增大,而残留比例随首循环混合气空燃比的增加而减少;进气道残留HC体积分数和比例随节气门开度的增加而降低;喷射相同燃料时,喷射时刻对残留HC体积分数和比例没有影响,但如果喷射发生在进气门开启之后,将导致燃烧的恶化.

Based on the analysis of engine＇s first firing cycle （FFC）, this paper presents the transient HC emission characteristics during cold-start in a small electronic fuel injected （EFI） SI engine fuelled with liquid petrol gas（LPG）. The results show that some fuel still remained in the intake pert even if the gaseous LPG was used in the tests. The residual hydrocarbon concentration in the intake port increased with fuel injection, while its proportion decreased. The residual ~n concentration and the ratio both decreased with the increasing of the throttle-opening angle. For the same fuel injection, injection time had little effect on the residual HC concentration and proportion. But the combustion in the cylinder became worse when the injection happened after the opening of the intake valve.