【摘要】 为了优化低负荷下甲醇发动机的燃烧及性能，将空气辅助喷射系统应用于甲醇发动机，并研究了喷气时刻、点火提前角和喷气脉宽对甲醇发动机燃烧特性的影响，结果表明：推迟喷气时刻至进气门开启之后有利于加快燃烧速度，提高发动机燃烧稳定性，尤其是在稀薄燃烧时的影响更明显，最佳的喷气时刻为300°CA BTDC．增大点火提前角可以缩短发动机的急燃期，提高燃烧稳定性，但是当喷气时刻推迟时，为了获得更好的动力性，最佳点火提前角也要推迟．增大喷气脉宽能优化发动机燃烧质量，提升发动机动力性和稳定性，但是当喷气时刻较早(闭阀喷射)或过晚时，喷气脉宽大于4 ms后动力性和燃烧稳定性增加不明显．并且在喷气时刻300°CA BTDC、喷气脉宽7 ms时，发动机的动力性和燃烧稳定性达到最佳．更多还原

【Abstract】 In order to optimize the combustion and performance of a methanol engine under low load,the airassisted injection system was applied to the methanol engine. The effect of injection timing,spark timing and mixture injection pulse width on the combustion characteristics and performance was studied. The results showed that delaying the injection timing until the intake valve opens is beneficial to accelerating the combustion speed and improving the combustion stability,especially during lean combustion. The best injection time is 300°CA BTDC.Advancing the spark timing can shorten the rapid combustion period of the engine and improve the combustion stability,but when the injection timing is delayed,in order to obtain a better power performance,the spark timing should also be delayed. Increasing the mixture injection pulse width can optimize the engine combustion quality and improve its power and stability. However,when the injection timing is too early(before the intake valve opens)or too late,the power performance and combustion stability will not be improved significantly after the mixture injection pulse width is greater than 4 ms. When the injection time is 300°CA BTDC and the jet pulse width is 7 ms,the engine will achieve the best power and combustion stability.更多还原