Study On Compound Control Method Of Gasoline Engine Transient Air Fuel Ratio Based On Emproved PID And Fuzzy Algorithm

In recent years,with the total emissions of atmospheric pollutants remain high,air pollution has become China’s first major environmental pollution problems.In view of the increasing use of automobile as a vehicle,the impact of gasoline engine emissions on atmospheric environment is increasing.The gasoline engine transient air-fuel ratio control of low precision and large amount of pollutant emissions,therefore,the research on the control of the transient air-fuel ratio of gasoline engine has important theoretical and practical significance to reduce the emission of gasoline engine.In order to solve the problem of the transient air-fuel ratio of gasoline engine due to the feedback delay and the dynamic effect of oil film,based on the Matlab software and Gasoline engine bench test platform,the transient air fuel ratio model of gasoline engine was established and the accuracy of the model is verified.The traditional PID control algorithm is improved by analyzing the time delay in the air-fuel ratio control of gasoline engine,which reduces the influence of the air-fuel ratio of gasoline engine.the paper summarizes the dynamic law of oil film in transient condition,and designs a kind of fuzzy oil film compensator to reduce the fluctuation of air fuel ratio caused by the dynamic effect of oil film based on the simulation and experimental data.Finally,the adaptive control method based on PID and fuzzy algorithm is proposed and the transient air-fuel ratio adaptive composite control model is established to improve the transient air-fuel ratio of gasoline engine.The simulation results show that,when the classical PID algorithm is used to control the air fuel ratio,the peak value of the air fuel ratio is 15.2,and then there is a large amplitude oscillation.The error correction can reduce the peak delay and reduce the fluctuation of oil film;fuzzy compensator is designed in this paper can significantly weaken the phenomenon of the transient air fuel ratio continues to increase and decrease;the parameter adaptive fuzzy PID compound control method,further reduce the fluctuation of the peak transient air fuel ratio,the air-fuel ratio of the amplitude of corresponding reduced opening to stability in the solar term door,the air-fuel ratio can quickly return to the stable value of about 14.7.