Research And Simulation Of Some Technology About Compressed Nature Gas Engine

The gasoline and diesel engine must be changed and use the alternative fuel in order to save energy and reduce pollution due to the shortage of the global petroleum resource and the serious air pollution problems.The research of alternative fuel engine tends to be an incrementally important discipline of engine techniques.As an ideal clean alternative fuel for diesel or gasoline, the natural gas has been concerned extentively in the world. Thus, compressed nature gas (CNG) engine will have extensive application for its high efficiency and low emission. The study of the techniques of learning burn for CNG engine is an important discipline, the development of the high-powered electronic controlled system has been a hotspot of CNG engine.The engeering of purging air has been starting, In order to promote the development of the natural gas vehicle techniques in our country, the research on the basic theory and the experiments on the electronic controlled CNG engine should be carried out.The following works has been fulfilled in the dissertation:development and the status quo of CNG engine is summarized, electronic controlled system of CNG engine is schemed. Based on these work, research and simulation of some technology about compressed nature gas engine have been lucubrated.As the ignition advanced angle, the air-fuel ratio and engine power, economical and emissions performance are closely related, so it is very necessary to study the control strategy of the air-fuel ratio and the ignition advanced angle. The traditional control methods are map enquirying methods by which it can control some variant related to performance, such as the ignition advanced angle, the air-fuel ratio, and so on. As these methods have some inherent limitation and there are always some errors in the control system, control accuracy will be affected. In the dissertation, a new control strategy of the air-fuel ratio and the ignition advanced angle are approached to replace the traditional method of map by using an artificial neural network (ANN).The feasibility and reliability of this ANN are analysed and studied. The characteristics of this ANN and system error are also simulated in MATLAB programes.In the dissertation,the fuzzy control theory is applied to the idle speed control.In order to combine the celerity of fuzzy control with the accuracy of PID control,a new method——fuzzy PID control is used.In MATLAB/Simulink simulation environment, the engine idling fuzzy control system model is built and the system tracking features and interference features are simulated too. The simulation shows that using this method in idle speed control system can greatly enhance the accuracy and respond speed, and it also has a strong anti-interference characteristic.