直喷比例对双喷射汽油机燃烧和排放影响的试验研究

An Experimental Study on the Effect of Direct-injection Ratio on the Combustion and Emission of Dual-injection Gasoline Engine

在一台装有双喷射系统的汽油机上进行试验,研究不同负荷时化学计量比混合气状态下直喷比例rDI对双喷射汽油机燃烧和排放的影响,结果表明:随着rDI的增加,当rDI低于40%时,缸压和缸内温度基本保持不变,当rDI大于40%时,缸压和缸内温度明显降低;CO先增加后减少,THC先减少后增加,NOx不断降低;微粒粒径由单峰分布转变为双峰分布,微粒排放总数量先降低后增加,积聚态微粒不断增加,而核态微粒变化规律则与负荷相关,且存在最佳的rDI,使微粒排放数量最少;当负荷增加时,NOx会增加,但其它气体和微粒的排放均降低。

The test on a gasoline engine equipped with dual-injection system is conducted to investigate the effects of direct-injection ratio rDIon the combustion and emission of that engine with stoichiometric mixture under different load conditions. The results show that with the increase of rDI,the pressure and temperature in cylinder are almost kept unchanged when rDIis less than 40%,and they obviously fall when rDIis more than 40%; CO emission increases first and then decreases,and the trend of THC emission is just the opposite,while NOxemission constantly lowers. With the increase of rDI,the distribution of particle size changes from single peak to double peaks,and the total particle emission rises first then falls,the emission of accumulation mode particle constantly raises,while that of nucleation mode particle depends on load,and there is an optimal rDIto make it minimum. With the increase of load,all the emissions of particle and pollutant gases fall except NOx,which rises with load going up.