The Research Of Single-cylinder Four-stroke Engine Idle Speed Control Strategy

With the increase of car ownership, urban traffic congestion is getting more and moreintensive. According to statistics, about 30% of the automobile engine fuel is consumed inthe idle condition, while 1/3 of the exhaust emissions from idle condition. At thelow-speed idle condition, the HC、CO and other pollutant emission is increasingsignificantly, but fuel consumption is increasing at the high-speed condition. Therefore,control strategy is particularly important to keep the engine speed stable at idle condition,as well as to alleviate the increasing serious environmental pollution and energy depletion.In this paper, Honda CB-125 engine is taken as the subject based on the test datausing the mean-value method. The model of engine at idle speed in Matlab/Simulink isconstructed to confirm the target parameters of the engine calibration. Pulse graphs ofengine injection and rotate speed response curves are obtained and the validity of themodel in different situations is proved.Widely used traditional PID control system, Variable- arguments PID control systemcontrol and flexible fuzzy-PID good at the nonlinear, time-varying, uncertaintiesconditions in idle speed are studied. Step responses of these three control systems aresimulated and compared. It shows that fuzzy-PID is better in strong anti-interference androbustness than the other two systems.The overall engine idle speed control strategy is designed, and idle speed stability ofthree systems are simulated and compared using the mean-value modle in the of HondaCB-125 engine. The results show that the fuzzy-PID control system is more suitable thanthe other two systems for nonlinear, time-variation and uncertainty of engine idle speedcontrol system in this paper.