Gasoline Engine Air-fuel Ratio Closed Loop Control And Monitoring System

Automotive exhaust emissions have been the main source of air pollution. With the intensification of people's consciousness of environmental protection and the more and stricter of emission regulation, reducing exhaust emissions has been the important content of environtnenta[ protection. In our country on-using automobiles have a high emission and pollute the air seriously. Most on-using automobiles adopt carburetor type gasoline engine, and in order to reduce those emissions, the effective measure is air-fuel ratio closed loop control working in three-way catalyst converter. The air-fuel ratio closed loop control adjusts the air-fuel ratio near the theoretical value by controlling the supplementary air of supplementary valve based on the signals of oxygen sensor, running speed and water temperature and which is necessary condition for three-way catalyst converter to work more efficiently. Among the arithmetic of air-fuel control, self-learning, self-adapting and self-correction can meet control demand but they also need on-line identifying of object model. They are complicated and need vast operation so they are difficult to realize and need lots of gantry experiments, taking time and hard sledding, which lead to their application success rate under people's expectation. In the past years fltzzy control has more wide application in control system. Fuzzy control does not need mathematical model, is a nonlinear control, has a good robust, and is not sensitive to the change of system parameters. So the system adopts fuzzy control, which is easy to realize, does not need vast experiments, and can reach better control effect. Based on the 15 operations regulated by GB14761?999, the control system was tested in some kinds of automotive. The result shows that air fuel ratio is controlled near the theoretical value under steady condition and exhaust emission is under the regulated value. The system is fit for the station of our country and the need of environmental protection It is easy to realize, has a low cost and a better control result, and is worth to spread.