增压直喷汽油机喷油策略对低速早燃的影响研究

Research on Low Speed Pre-Ignition with Fuel Injection Strategy for Turbocharged Gasoline Engine of Direct Injection

试验研究了喷油策略对增压直喷汽油机低速早燃的影响。研究结果表明：低速早燃现象在发动机正常运行过程中随机且非连续的发生,发生时最高燃烧压力显著上升并引发强烈的爆震;空燃比加浓（过量空气系数0.75～0.90）可以显著地降低低速早燃的发生频率;单次喷射的喷油开始时刻过于提前（330～300°CA BTDC）或者推后（250～210°CA BTDC）都将增大低速早燃的发生频率;采用高的喷油压力（15MPa）对于低速早燃的发生频率具有抑制的趋势;当第一次喷油开始时刻较为提前（330～300°CA BTDC）时,相比单次喷射策略,二次喷射策略能够较明显地降低低速早燃的发生频率。

The effect of fuel injection strategy on low speed pre-ignition（LSPI）of turbocharged gasoline engine of direct injection（T-GDI）was researched through experiment.The results show that LSPI happens occasionally,and peak pressure rises significantly and heavy knock is induced.The frequency of LSPI decreases with rich mixture（lambda=0.75～0.90）combustion,but increases when injection timing is much earlier（330～300°CA BTDC）or much later（250～210°CA BTDC）.Moreover,high fuel pressure（15MPa）can probably reduce LSPI.When the injection timing is earlier（SOI1=330～300°CA BTDC）,a split injection strategy has much better effect on reducing LSPI frequency than single injection.