Analyse And Control On Air-Fel Ratio Consistency Of Two-Stroke Multi-Cylinder Piston Engine

Air-fuel ratio consistency between the cylinder control of multi-cylinder engine has significant effect on improving power performance,the efficiency,vibration noise of the engine,as well as the requirements of fault diagnosis.The existing hardware system can support injectors drove alone,on the software a variable for each fuel injector set simply,which provided the basic conditions for the implementation of individual cylinder control.This paper researched a two-stroke opposed two-cylinder engine,the air-fuel ratio inconsistency was studied,the electronic control system of the engine was designed,and bench test of air-fuel ratio consistency control strategy was established.The main work was as follow:(1)Air-fuel ratio inconsistent influence factors and its sources of two-cylinder engine were analyzed,starting from the reason of the difference,GT-power engine numerical calculation model of cylinder inconsistencies was set,the simulation results compared with the experiment,and the causes of air-fuel ratio inconsistencies between cylinder were analyzed.The main reasons are the inconsistent of inlet air and fuel injection of each cylinder;(2)According to the characteristic of the engine,individual cylinder fuel compensated air-fuel ratio control strategy based on deviation was put forward.Two-cylinder engine air-fuel ratio consistency control model was established by MATLAB/Simulink,the dynamic effect of Universal Exhaust Gas Oxygen sensor was considered while establishing the model,and coupled with the GT-power engine model for closed loop control of air-fuel ratio consistency between the cylinders;(3)The engine electronic control system was redesign.MC9S12DP512 was selected as the microcontroller,signal processing circuit and actuators drive circuits and so on were designed,the software program of electronic control unit(ECU)was written,and fuel compensate control program was written based on the proposed control strategy,while anti-interference measures were taken on the hardware and software.(4)The ECU Simulation experiment was accomplished,the validity of the control program was verified and the designed ECU can reach the desired functions.To verify the correctness of control strategy,the engine bench test was conducted.The result show that the control strategy can increase the air-fuel ratio consistency between cylinders.