采用两次喷油策略降低直喷增压汽油机爆震和碳烟排放及改善冷起动特性的研究

Improvement of Knocking,Smoke and HC Emissions in Cold Starting by Two Stage Injection for Turbocharged GDI Engine

在某款增压直喷汽油机上,分别在爆震工况及冷起动工况采用燃油两次喷油策略和单次喷油策略,通过对比两种喷油策略的结果发现:在爆震工况,采用合适的两次喷油策略可使CA50提前3.3°CA,抑制发动机爆震倾向,并使碳烟排放从0.59FSN降低到0.45FSN;在冷起动工况,采用合适的两次喷油策略有利于改善着火性能和提高燃烧稳定性,使得最迟点火提前角比单次喷油推迟47°CA,可以提高排气温度,使三元催化器快速起燃,降低HC排放。

To solve problems in gasoline direct iniection engine downsizing with boosting, VVT etc. , such as knocking and soot emission in high load condition and high unburned HC emissions in cold starting condition, both single and two stage injection strategies were experimentally investigated under these conditions in a turboeharged gasoline direct-injection engine. It is found that by using optimized two stage injection strategy,in knocking condition the CA50 timing advances by 3. 3℃A and the knocking trend is suppressed, engine soot emission decreases from 0.59 FSN to 0.45 FSN,and in cold starting, fuel ignition and combustion stability are improved,the ignition timing can retard by about 47℃A at most compared to single injection,thus accelerating the catalytic converter warming up,benefitial to HC emission reduction.