喷油压力和EGR策略对柴油机瞬变性能的影响

Effects of EGR and Injection Strategies on Diesel Performance during Transient Conditions

分析了喷油压力和EGR策略对柴油机恒转速增转矩的瞬变工况下累积烟度和烟度峰值的影响。研究表明:分段轨压策略中,在490N·m负荷时,增加喷油压力,累积烟度和烟度峰值的下降幅度最大;在EGR率为5%时,全程原机喷油压力策略对瞬变过程中的烟度峰值影响较小;在EGR率为5%的20%~100%恒转速增转矩瞬变工况下,提高起始负荷和采用全程原机喷油压力策略,均能有效降低烟度峰值;在20%~100%恒转速增转矩的瞬变过程开始后的1.5s关闭EGR阀,能有效降低烟度峰值,结合分段轨压策略,能进一步降低烟度峰值。

The effects of EGR and injection strategies on the cumulative smoke density and smoke peak value of diesel during transient condition is analyzed.The results show that,as one of the strategies of"Sectional rail pressure",raising the pressure when the load is higher than 490 N·m can improve the cumulative and density peak value of smoke furthest.But when the EGR ratio is 5%,the strategy of injection pressure of original engine during the whole process has a little influence on the smoke peak value.The peek value of smoke density can be further reduced by raising the initial load as well as adopting the strategy of injection pressure of original engine during the whole process under the transient condition that the load is from 20%to 100%under constant speed while the EGR rate is 5%.The peak value of smoke density will be effectively improved when turning off the EGR valve 1.5 seconds after the transient condition begins,and will be further reduced while coupling the"Sectional rail pressure"strategies.