为克服低速早燃现象,以提高汽油机低速转矩,改善汽车的驾驶性和降低油耗,首先对一款采用米勒循环的增压汽油机低速早燃特性进行了参数敏感性试验分析,结果发现,降低冷却液和进气温度和加浓混合气,能在一定程度上抑制早燃,但作用有限,不能达到期望指标.接着采用光纤传感器监测燃烧过程,发现早燃主要发生在排气门附近,而CFD缸内流场分析表明此区域湍动能较弱,可能是早燃发生的主要原因.据此,通过改进缸盖进气道和导气屏,提升滚流比和湍动能,有效抑制了早燃,实现了期望目标.%For overcoming low-speed pre-ignition phenomenon to increase the low-speed torque of gasoline engine, improve the driveability and reduce the fuel consumption of vehicle, firstly an experimental parameter sensi-tivity analysis on the low-speed pre-ignition characteristics of a turbocharged gasoline engine with Miller cycle is con-ducted, and the results show that though lowering the temperatures of intake gas and coolant and using rich mixture can suppress pre-ignition to a certain degree, the effects are limited and so can not achieve desired indicators. Then monitoring combustion process by using optical fibre sensor finds that pre-ignition mainly occurs at the vicinity of ex-haust valve, and the CFD analysis on in-cylinder flow reveals that the weak turbulent kinetic energy in that area is probably the main cause of pre-ignition. On this basis, through the modification of gas guiding mask and intake port in cylinder head to increase the tumble ratio and turbulent kinetic energy, pre-ignition is effectively suppressed and the desired target is achieved.
展开▼
