汽油机进气动态特性建模与仿真研究

Modeling and Simulation Study of Intake Manifold Air Flow Dynamic Characteristics for SI Engine

从汽油机实际工作过程出发,运用平均值建模方法构建了汽油机进气管内空气动态特性模型,并基于稳态试验数据对模型待定参数进行了辨识。通过引入转速修正项对模型结构进行了修正,特别是对节气门处空气质量流量的饱和非线性特性进行了补偿,解决了原节气门处空气质量流量子模型在较大节气门开度下误差较大的问题。台架试验和计算机仿真对比结果显示,在稳态工况下,进气压力模型仿真与实测值的最大相对误差不超过±2%,在节气门阶跃的瞬态工况下,最大误差不超过±3%。相关模型可直接用于基于模型的进气口空气流量预测、空燃比控制器设计,也可作为汽油机模型的一部分,为空燃比控制策略软硬件在环仿真提供条件。

An intake air dynamic characteristic average-value model was constructed, its parameters to be determined were identified based on steady test data. By introducing a speed correction term to modify the model structure, especially to compensate the saturated nonlinear characteristics of air mass flow at throttle, the excessive deviation problem of original throttle flow sub-model during wide opening was solved. The comparison of bench test data with numerical simulation results shows that values of intake pressure, air mass flow at throttle and intake port are all very consistent, indicating the model and the parameters have high accuracy. In steady conditions, the max. relative error of intake pressure is less than ±2%, and in transient state （unit-step）conditions, the max. relative error does not exceed ±3%. This model can be used directly in model-based intake port air mass flow prediction, air/fuel ratio controller design, and as a part of the engine model in software and hardware in-loop simulation for air/fuel ratio control strategy.