利用扫气抑制增压直喷汽油机“超爆”的研究

Investigation on Suppressing Super-knock of Turbocharged GDI Engine by Scavenging

"超爆"是增压汽油机的一种异常燃烧模式,这种燃烧在火花塞点火之前自发着火,但又不同于HCCI(汽油机均质压燃)燃烧。结合"超爆"发生的条件,提出了利用扫气功能降低混合气温度,部分消除"超爆"发生的条件,并对比了不同配气正时策略下扫气功能抑制"超爆"的效果。试验结果表明,扫气能有效抑制"超爆",气门正时"进排气门都提前打开和关闭"控制策略相对"进排气门都滞后打开和关闭"控制策略抑制"超爆"效果更好。

Super-knock is an abnormal combustion mode of turbocharged gasoline engine. The abnormal combustion occurs spontaneously before spark ignition, but is different from homogeneous charge compression ignition （HCCI）. Based on the con- dition of super-knock, the method of removing super-knock condition partly by decreasing the temperature of mixed gas with scavenging was put forward. Furthermore, the effects of suppressing super-knock by scavenging were compared under different strategies of valve timing. The results show that scavenging can suppress the super-knock effectively. Compared with the late opening and closing control strategy of intake and exhaust valves, their early opening and closing strategy has a better effect on super-knock suppression.