二次喷射时刻对 GDI 汽油机颗粒物排放的影响

研究了缸内直喷汽油机在不同二次喷射时刻条件下的颗粒物粒径分布特性。试验工况为最大扭矩转速2000 r／min工况，负荷率分别为10％，30％，60％。试验结果表明：不同二次喷射时刻下，缸内直喷汽油机颗粒物粒径呈单峰分布，低负荷数量峰值在对应的积聚模态70 nm附近。低负荷下，合理优化二次喷油时刻可以降低颗粒物排放；中等负荷时，单次喷射的颗粒物排放远低于二次喷射。

Effects of Secondary Fuel Injection Timing on Particle Emission of GDI Engine

The characteristics of particle size distribution under different secondary injection timings were researched under the 10% ,30% and 60% load conditions at the maximum torque speed (2 000 r/min) of GDI engine .The results indicate that the particle size of secondary injection timing shows unimodal distribution with the number peak of low load around 70 nm accumu‐lation mode .At low load ,the reasonable optimization of secondary fuel injection timing can reduce particle emission .At medi‐um load ,the particle emission of single injection is far less than that of secondary fuel injection .