基于EGR策略的重型柴油机瞬态空燃比优化控制

针对某些重型柴油机在进气中冷后加入足量的EGR较为困难,瞬态工况下EGR优化后的发动机排放性能恶化的问题,从精确控制EGR流量、优化空燃比、降低排放的目的出发,在一台CY6D180高压共轨重型柴油机上进行了大量的试验研究。基于排放优化原则,研究了利用节气阀配合EGR阀引入EGR后的发动机稳态特性,提出了一种两阀联合关开优化发动机瞬变排放性能的策略。进行了瞬态工况条件下的对比试验验证。结果表明:本文设计的瞬态空燃比控制方法在保证烟度排放值在3.5%限度内的情况下,NOx的排放量也不超过稳态工况点的10%。

Transient air-to-fuel ratio control on heavy duty diesel engine based on EGR technology

Aiming at the problem that adding sufficient quantities of EGR is difficult for heavy duty diesel engine after the intercooler of intake and emissions is deteriorated in transient operating conditions,a lot of experiments were carried out on a CY6D180 high pressure common rail diesel engine by controlling EGR flow accurately to optimize air-to-fuel ratio,so improving the emissions performance of engine.Based on emissions optimization principle,the steady-state characteristics of engine was studied under the condition of adding EGR after the EGR valve introducted by throttle.A new strategy of two valve turn off and turn on to optimize the engine transient emissions was proposed.The emissions effects under transient operating conditions were verified by experiments,the results show that the proposed strategy can reduce the smoke emission lower than 3.5% as well as NOx emission lower than 10% steady-state condition point.