带 EGR 的两段式 VVL 发动机点火策略仿真分析

Simulation and Analysis of Ignition Strategy for a Two Step Variable Valve Lift Engine with EGR

基于GT-Power软件构建两段式可变气门升程发动机性能仿真模型,并对模型进行标定。燃烧模型及外特性计算结果与实测数据吻合,验证了模型的有效性。基于该仿真模型,分析采用大、小两种不同进气门升程时点火提前角对发动机爆震、动力性、经济性及NOx排放特性的影响。无EGR时,使用小进气门升程时较大气门升程有更高的缸内峰值压力和最高缸内温度,更易爆震且NOx排放也更高;在各自爆震边界点火时,两者动力性及经济性相近;EGR增加后爆震趋势减弱。

A simulation model of a two -step variable valve lift engine based on GT -Power is established and calibrated. The combustion model and the external characteristic calculation results match well with the measured data, proving validity of the model. Based on this model, effect of ignition advance angle on engine knock, power performance, fuel economy and NOx emissions is investigated under both high and low intake valve lift. The results also indicate that, compared with the case of high valve lift, higher in-cylinder peak pressure and the maximum in-cylinder temperature are expected under the case of low valve lift, which is more vulnerable to engine knock and more NOx emissions at the same ignition timing. The same power performance and fuel economy are expected when the ignition timing is kept at each of their knock boundary conditions, and EGR offers a considerable potential to reduce the trend of post knock.