摘要:汽车发动机的燃料供给及其控制系统可以说是整机的心脏,其工作状况极大程度 地影响着发动机的动力性、燃料经济性、有害物排放量、以及怠速稳定性、加速平顺 性等运行性能。
本文通过调研国内外先进的电控技术,对四缸汽油发动机电子控制系统进行了研 究和设计。主要内容包括:制定合理的空燃比控制策略;在 Matlab/Simulink 环境中 建立电控系统仿真模型,通过综合仿真验证控制策略和控制算法的可行性;建立发动 机仿真标定模型,并进行仿真标定获得喷油初始MAP。
本文的主要结论和创新点如下:
1)采用参数模糊自整定PID控制算法控制怠速转速的稳定性,是一种较好的方案;本文通过仿真验证了其可行性和优越性。
2)通过对发动机模型进行改进和添加燃油蒸发与动态油膜模型使其可以模拟稳 态也可以模拟瞬态;利用一反正切函数来模拟氧传感器的输出特性,从而使发动机模 型可以实现空燃比闭环控制的模拟;控制器模型的模块化建立方法为控制软件的模块 化设计提供了理论基础。
3)建立了发动机仿真标定模型,并利用仿真标定的方法替代部分的实机试验获得 初始MAP数据。在对初始 MAP 数据的优化处理中引入线性插值法,通过对比和理论分析,表明其是一种较好的方法。
关键词:汽油发动机,电控系统,控制策略,ECU,仿真标定
Abstract:Electronic fuel supply system is regarded as the most significant element in the engine .It has a serious influence to reducethe exhaust emissions and improve the power and economy performance.
Based on tracking of the domestic and foreign advanced electronic controltechnology, the electronic control system was researched and developed for four-cylinder gasoline engines in this dissertation.Primary conclusion includes following items. First, the reasonable control strategy and algorithm were established. Second, the simulative model of electric control system was set up in Matlab/Simulink environment, in which the feasible control strategy and algorithm were confirmed by integrated simulation. Then the simulative model of engine calibration was built, by which the original MAP of fuel injection was obtained.In this dissertation, the main innovations and conclusions are as
follows:
1)Using Fuzzy self-adative PID control algorithm to control the idle speed was a preferable way. And its feasibility and advantages were confirmed by simulative experiments afterward.
2) An improved 4-cylinder 4-stroke gasoline engine model, the air/fuelratio and ignition controller models which were relevant to the control strategy were established. By appending fuel dynamic evaporation model to make the engine model be able to simulate both stable state and transient state. An arctangent function transform was improved to simulate the output characteristic of oxygenic sensor, which made the closed loop control for the air/fuel ratio be simulated in the engine model. The modularized method was adopted in controller's upbuilding, which could be the reference for control software's design.
3) Engine simulative calibration model was established, in which the simulated calibration experiment was done and the primal oil MAP data was obtained.And Least square method, which can increase the efficiency to get the original MAP data, was advanced by comparison and theory analysis.
Keyword:Gasoline engine, Electronic control system, Control strategy, ECU, Simulative calibration