Research On Monitoring Method Of Engine Combustion And Emission Based On Model And Real-time Signal

The introduction of Real Drive Emission(RDE)regulations and pollutant emission limits in National VI regulations have brought huge challenges to the actual operation and control of traditional gasoline-powered vehicles.However,the monitoring signals in the current gasoline engine system are limited and cannot directly reflect key information such as combustion and emissions during operation.To solve this problem,this paper proposes a virtual cylinder pressure reconstruction method based on the combination of combustion prediction model and engine actual measurement information to obtain real-time combustion information such as cylinder pressure and temperature.Based on the in-cylinder temperature and pressure conditions,the engine transient pollutant emission model is developed,and the cycle-based emission prediction is realized,which can serve the transient combustion process monitoring and pollutant emission control in the actual operation of the gasoline engine.In this paper,based on the single-cylinder thermodynamic engine experimental platform,a semi-empirical engine heat release rule prediction model based on operating conditions is established.Through the use of high-resolution crank angle sensor photoelectric encoder combined with crankshaft dynamics,the local change of the crankshaft angular velocity signal is analyzed to obtain the actual maximum burst pressure phase in the cylinder,and then to correct the engine heat release law prediction model given The position and shape of the in-cylinder pressure curve change,so as to realize the reconstruction of the cylinder pressure curve in the transient engine operation.By checking with the measured data of the cylinder pressure sensor,under the 20verification conditions used,the instantaneous cylinder pressure curve is reconstructed based on the model and limited information,and the IMEP relative error is within 8%,and the maximum explosion pressure is within 10%.Based on the reconstructed instantaneous cylinder pressure information and a combination of mechanism and experience,the prediction models of the three main pollutants of engine NO_X,CO and HC were established for different emission characteristics.Among them,based on the use of reconstructed cylinder pressure information to derive the development process of the burned zone,the two-step carbon fuel oxidation mechanism and the simplified Zeldovich mechanism are used to construct the CO and NO_X emission mechanism;the two-zone assumption is used to construct the HC emission generation model.Experimental emission tests show that in steady-state conditions,the accuracy of the NO_X emission prediction model reaches85%,CO reaches 75%,and HC reaches 90%.Based on the model and limited real-time signals,this research preliminarily establishes a cycle-based combustion process and pollutant emission monitoring method,which provides basic information for RDE testing and optimization of engine transient operating conditions in practical applications.