Research On Integration And Matching Of EGR System And Supercharging System Of Miller Cycle Engine

Due to global energy shortages and environmental degradation,the development of hybrid engines has become one of the major technical solutions to deal with energy shortages and environmental crises in recent years.Compared with the traditional Alto cycle,the Miller cycle has the advantages of small pump loss and high effective thermal efficiency,so it has become an important thermal cycle of hybrid electric vehicles.This article is supported by the national key R & D project "Hybrid Engine Whole Machine Design and Integrated Development".This paper conducts an integrated optimization and matching study on the EGR system and the supercharging system of the Miller cycle engine.Thermal efficiency and torque are optimized.The research work helps to promote the design of high-efficiency domestic hybrid gasoline engines and improve the performance of the entire engine.Carrying out research on new energy electric vehicle powertrain systems has important academic value and engineering application value.In this paper,a domestic engine is used as the prototype engine for the thesis research.The mathematical model of the working process of each subsystem of the turbocharged gasoline engine is established.The simulation calculation model of the gasoline engine based on GT-POWER is compared with the test data to verify the model accuracy.Carried out a simulation study of the system characteristics of the Miller cycle engine,and analyzed the effect of the late intake valve closing Miller cycle on the engine ventilation process under the driving conditions of the hybrid vehicle.The effect of the angle of closure on the power and fuel economy of the engine was studied;the effect of the EGR system on the emissions,power and fuel economy of the Miller cycle engine was analyzed,and the backflow problem of the high-pressure EGR pipeline was studied;The influence of the opening of the bypass valve on the engine performance was studied,and the optimal performance of the opening of the bypass valve was optimized.The optimal opening of the bypass valve was obtained under full engine operating conditions,and the Miller cycle engine and the supercharger were rematched.The genetic algorithm is determined as the optimization algorithm in this study,and the problem of the multi-objective optimization model of the Miller cycle engine is mathematically described.Developed a coupling program of GT-Power and MATLAB / Simulink,designed the parameters of the genetic algorithm,and finally obtained the optimization results of the genetic algorithm.According to the optimization results,the MAP of the bypass valve opening,the EGR rate map,and the boost pressure were obtained.Pressure MAP and intake flow MAP.The integration and optimization of the Miller cycle engine EGR system and the supercharging system have been completed.There are 51 figures,7 tables and 78 references in this thesis.