二次燃油喷射对自吸直喷汽油机低速性能影响的试验研究

Experimental Investigation into Influence of Split-Injection on Low-Speed Performance of Gasoline Direct Injection Engine

对一台自吸直喷汽油机采用不同的燃油喷射模式在2 000r/min全负荷工况进行试验,研究了二次喷射对发动机低速动力性和经济性的影响,并根据缸压参数、燃烧参数及排放物的变化规律对二次喷射影响发动机低速性能的机理进行了探讨。结果表明,相比单次喷射,通过优化二次喷射时刻可以使动力性提升5%,经济性提升约6%。二次喷射的优化机理主要是实现了燃烧室内油气浓度的不均匀分布,可提升燃烧速度,通过分层燃烧实现动力性和油耗的改善。

The influence of split-injection on the low-speed performance of gasoline direct injection （GDI） engine was researched experimentally w ith fu l l load at the operating point of 2 000 r /m in using a series of injection modules, focusing on the effect of split-injection on power and fuel economy. And the mechanism of the effect of split injection on the engine performance at low speed was investigated by analyzing thechanges of cylinder pressure, combustion and emissions. The result indicates the optimized split-injection generating the strat if ied stoichiometric mixture in the combustion chamber can accelerate the flamepropagation,and improve the power and fuel economy by 5 U and 6 U respectively.