机外净化技术对 GDI 发动机颗粒排放的影响

通过缸内直喷汽油机颗粒测量试验，研究了怠速工况、最大扭矩工况及常用工况下三效催化器（TWC）和汽油机用颗粒捕集器（GPF）对发动机尾气中颗粒数量浓度及质量浓度的处理效率。结果表明：在低转速小负荷工况，三效催化器与颗粒捕集器对颗粒具有较高的处理效率；随着转速与负荷的增加，两者的处理效率均下降，三效催化器对颗粒处理能力明显降低，而颗粒捕集器整体保持较高的捕集效率；当二者联合工作时，在常用行驶工况下对颗粒的捕集效率达到80％以上。在高转速大负荷工况，由于尾气空速增加，颗粒捕集器捕集效率下降导致整个后处理系统对颗粒的处理效率降低。

Influence of External Purification Technology on Particulate Emission of GDI Engine

The purification efficiencies of three‐way catalyst (TWC) and gasoline particulate filter (GPF) on particulate emis‐sion number concentration and mass concentration under the conditions of idle ,maximum torque and common running speed were researched on a GDI engine bench .The results showed that TWC and GPF had higher processing efficiency at low load and low speed .Their purification efficiency decreased with the increase of speed and load ,but GPF remained a relative higher effi‐ciency than TWC .The joint operation of TWC and GPF could lead to 80% purification efficiency in common running operation conditions .At high load and high speed ,the purification efficiency of the whole aftertreatment system decreased due to the de‐crease of GPF efficiency led by the increase of exhaust velocity .