主动预燃室式直喷汽油机稀薄燃烧性能研究

为明晰不同点火方式对汽油机稀薄燃烧特性的影响规律，在一款排量为0.5L的研究型单缸机上试验研究了传统火花塞和主动预燃室两种不同点火方式下发动机燃烧及排放特性，探索主动预燃室拓展稀薄燃烧极限的多种影响因素。研究结果表明，稀薄燃烧可有效降低油耗，提高发动机热效率。传统点火线圈的稀燃极限处于过量空气系数1.5附近，最高指示热效率为45.0%，而采用主动预燃室系统后，稀燃极限可进一步拓展，过量空气系数可达2.0，指示热效率提升至46.5%，氮氧化物排放比采用传统火花塞点火技术时降低约88%；主动预燃室匹配高压缩比14.80的燃烧系统，可进一步拓展稀燃极限至过量空气系数2.1，指示热效率可达48.0%，氮氧化物排放继续降低，在过量空气系数采用2.1时NOx排放最低可达58×10-6。

The Lean Combustion and Emission Performance of a GasolineDirect Injection Engine with Active Pre-chamber

In order to clarify the effect of ignition system on lean burn characteristics, experiments were carried out with conventional spark plug ignition and active pre-chamber on a 0.5L single cylinder research engine(SCRE). The ways to extend the lean burn limitation were also investigated. The results show that, lean burn can effectively reduce the fuel consumption and increase the thermal efficiency of a gasoline engine. Adopting traditional spark plug system can extend the lean burn limit to excess air ratio of 1.5 with the gross indicated thermal efficiency of 45.0% limited by unstable combustion, while resembling active pre-chamber system can achieve gross indicated thermal efficiency(GITE) of 46.5% with the excess air ratio of 2.0 and the help of much more stable combustion. Active pre-chamber system can be reduced by 88% compared with conventional spark plug system. Increasing the compression ratio to 14.80 can further increase the GITE to 48.0% and reduce the NOx emission to the minimum 58×10-6 with the excess air ratio of 2.1.