可变增量的EGR控制策略对柴油机瞬态排放的影响

Incremental Variable EGR Strategy for Optimizing Transient Emissions of Turbo-Charged Diesel Engines

针对涡轮增压柴油发动机在瞬态工况下因涡轮延迟现象所导致的碳氢化合物(THC)和颗粒物(PM)排放相对较高的问题,研究瞬态工况下废气再循环(EGR)变化率与发动机动力性能和排放性能之间的变化规律,搭建基于AVLPUMA系统的柴油发动机瞬态排放测试平台,监测瞬态工况下EGR变化率、进气质量流量与NOx、PM和THC排放物之间的变化关系,在此基础上提出一种可变增量的EGR控制策略.结果表明:通过该策略能够快速有效地降低发动机的喷油量,提高新鲜空气进入气缸的质量流量,提高瞬态空燃比,改善燃烧,最大程度地降低涡轮延迟现象对发动机造成的不利影响;在试验工况条件下,使用该策略可使累计颗粒物排放最高降低83.5%,.

Turbo-lag is an important factor to bring THC and particulate emission spikes under transient operating conditions. An incremental variable EGR reduction strategy was developed and investigated to improve the transient performance and emissions of a commercial turbo-charged diesel engine. The diesel engine used in this experiment was controlled by an AVL PUMA control system. Both gaseous and particulate emissions were measured by various fast response diagnostic analyzers. Results show that the incremental variable EGR reduction strategy effectively im- proves intake air mass flow rates during acceleration transient periods. With the improvement of fuel injection quantity, instantaneous AFR and engine combustion, this novel transient strategy can significantly reduce particulate number by up to 83.5% under the constant speed acceleration transient condition.