低压缸内直喷CNG发动机燃烧特性的影响因素

Influence Factors of Combustion Characteristics of a Low Pressure Direct Injection CNG Engine

自主研发了低压缸内直喷压缩天燃气(CNG)发动机,研究了过量空气系数、喷气时刻、点火能量、点火时刻等对发动机燃烧特性的影响.结果表明,喷气时刻对低压缸内直喷CNG发动机的燃烧性能有很大影响,对于给定的工况,发动机存在一个最佳喷气提前角;提高点火能量有助于改善CNG发动机的燃烧过程,增大点火提前角,可以在一定程度上弥补由于天然气燃料火焰传播速度慢所导致的热效率下降,从而改善发动机缸内的燃烧过程,使其功率增加,燃气消耗率降低.

A low pressure direct injection compressed natural gas（CNG） engine was developed based on a singlecylinder gasoline engine.The combustion characteristics of the CNG engine under various lambda,injection timing,ignition energy and ignition timing were investigated.The results show that CNG injection timing has a great influence on engine combustion performance.For a given engine operation condition,there exists an optimum injection timing.High ignition energy can improve the combustion process of the CNG engine.Increasing the spark advanced angle can prevent to some degree the dropping of thermal efficiency caused by slow flame propagation of natural gas,hence improving the combustion process,increasing the power and decreasing the gas comsumption of the CNG engine.