烟度限制策略对柴油机瞬态性能的影响研究

Effects of Smoke Limit Strategy on Transient Performance of Diesel Engine

针对柴油机瞬态工况出现冒烟的问题,设计了一种基于扭矩协调的烟度限制控制策略,实现了柴油机瞬态工况下烟度的控制,系统研究了不同过量空气系数(Ф_(a))限值对柴油机瞬态工况下动力性能和排放的影响。结果表明:Ф_(a)限值可以限制柴油机瞬态过程中的循环喷油量,保证期望的过量空气系数,从而限制炭烟的排放。Ф_(a)限值为1.51时,烟度较低,与Ф_(a)限值1.01对比,1200 r/min和3200 r/min转速下烟度峰值降幅分别达到85%和88%;Ф_(a)限值为1.51时,瞬态动力响应较慢,与Ф_(a)限值1.01对比,1200 r/min和3200 r/min转速下瞬态响应分别延迟了58%和57%。为了确保柴油机满足瞬态工况下的动力性需求,防止瞬态过程过量空气系数过小而导致过高的烟度,应该标定合适的Ф_(a)限值。

Aiming at the problem of smoke under transient conditions, the control strategy of smoke limit based on torque coordination was designed to realize the smoke emission control of diesel engine under transient conditions. The effects of different excess air coefficient limits on the power performance and emission of diesel engine under transient conditions were systematically studied. The results show that the excess air coefficient limit can limit the cycle fuel injection of diesel engine during the transient process so that the expected excess air coefficient was acquired and the smoke emission is hence controlled. The smoke emission is less and the transient power response is slower at the excess air coefficient of 1.51. Compared with 1.01 excess air coefficient, the peak smoke decreases by 85% and 88% and the transient dynamic response delays by 58% and 57% at 1 200 r/min and 3 200 r/min respectively. In order to meet the power requirement and prevent the higher smoke emission due to a large excessive air coefficient under transient conditions, an appropriate excess air coefficient limit should be configured.