Study On Parameter Identification Of Fuel Film Model For Gasoline Engine

It is the efficient way to reduce the engine emission by using 3-way catalyst converter,which is offen used to satifyed the strick emission regulation.The reaserch has showed that the engine emission includes CO, HC and NO X ,which are the most contaminative source to the air. Under stoichiometric air fuel ratio condition The NO X emission is very high,while CO, HC emossions are low, 3-way catalyst converter can oxidate and deoxidize exhaust emission efficiently with the stoichiometric air fuel ratio,which is the way to get the best depurative efficiency and the goal of air fuel ratio control. But during the transient process when the fuel is intrduced into the intake manifold,The fuel film formed on the manifold wall because of the fuel flow dynamics ,which affect the control precision of air fuel ratio.Above all,Solving the problem of air fuel ratio control during the transcient process to make the 3-way catalyst converter working in the ideal condition is the important way to reduce the emission during the transient process.Accounting for the fuel film problem during engine transient process and making the the 3-way catalyst converter work under the biggest converting efficiency and reduing the engine emmsion , based on the Item"Study and Demonstration of Key Technology for the Low-emission Electronic controlled Gasoline Vehicles Whose Weight are below 3.5 Ton"in this thesis the fuel film model was built and the two parameters were calculated.Base on the fuel film model, the simulation and transient experiment were researched.The main work in this thesis includes:1) Computer data acquisition system has been designed in this thesis in order to satisfy the need of high speed of data acquisition ,which is based on Labview . The data acquisition system guarantees the veracity and synchronization of data acquisition. The acquired data can also be diplayed in the form of graph, which made the experimenter undstand and grasp the course of the experiment in time.2) The theory of fuel film model and fuel film compensator has been expatiated in detail in this thesis,furthermore the way for calculating the fuel film parameter and the least-squares estimation were introduced.3) Accounting for the factors influenting the two parameters this thesis hat designed the project of datas acquisition, the datas acquired from engine experiment were to calculate the fuel film model parameter X andτthrough least-squares estimation.furthermore analyze the rule of parameter。4) The Mean-Value Engine Model was built in the Matlab/Simulink module to validate the parameters'correctness,which are calculated through least-squares estimation.