Study On Control Model And Simulation Of Wiebe-based Equation Of Marine High Pressure Common Rail Diesel Engine

According to the difference between the target speed and the actual speed,the conventional high pressure common rail electronic control injection system has fuzzy control of the fuel injection volume,so that the speed,torque and other parameters can roughly meet the current demand.This method has poor control accuracy,resulting in high fuel waste and emission level,which requires higher precise control strategy of fuel injection.The real-time combustion process control model based on the Wiebe equation has a good potential to simultaneously save energy and reduce emissions,and with the development of the engine control unit(ECU),its computing capacity can meet the requirements of model-based control computing.In this paper,the Wiebe equation parameters of TBD620 single-cylinder diesel engine were calculated and analyzed.The control model was established by using 50% of Mass Fraction Burned and Indicated Mean Effective Pressure.The thermodynamic process in the cylinder was analyzed by using one-dimension and three-dimensional simulation software,and the control model and the Wiebe equation parameter calculation method were simulated and verified.The main research contents are:(1)The heat release rate curve and the Indicated Mean Effective Pressure(IMEP)were calculated by using the parameters obtained from the TBD620 high pressure common rail single cylinder diesel engine test,and then the cumulative heat release and the burned fraction curves were obtained.(2)According to the heat release rate curve and the burned fraction curve obtained by calculation,the Wiebe equation parameters under various working conditions were calculated and analyzed,and 50% of Mass Fraction Burned(MFB50)was obtained according to the Wiebe equation.According to MFB50 and IMEP control model theory,the fuel injection control model strategy of diesel engine based on Wiebe equation was determined.(3)The one-dimensional simulation model was established according to the TBD620single-cylinder machine structure,and the coupling control model was established according to the MFB50 and IMEP control model theory,and the steady-state and transient simulation operations were carried out for the one-dimensional simulation model.The results show that MFB50 and IMEP control modules can accurately and real-time control the fuel injection starting point and the fuel injection volume,the steady-state adjustment rate is less than 2%,the steady-state adjustment time is within 5s after the steady-state adjustment,the speed regulation is accurate under the transient condition,and each parameter changes steadily.(4)A three-dimensional simulation model was established according to the in-cylinder structure of TBD620 single cylinder machine.The thermodynamic parameters and emission parameters of in-cylinder combustion process were obtained through simulation calculation and analyzed.The parameter calculation method of Wiebe equation was verified by the cylinder pressure curve.The results show that the combustion process is consistent with that of the Wiebe equation,and the parameter calculation method of the Wiebe equation is accurate and reasonable.