Combustion Optimization Of Hybrid Dedicated Engine And Vehicle Matching

As energy and environmental issues become increasingly prominent,fuel and emission regulations in the automotive industry are becoming more stringent.efficient and clean combustion technology of engine and hybrid technology have become the focus of current research and development in the automotive industry.Hybrid vehicles show huge advantages in energy conservation and emission reduction.In order to further improve the economics of the vehicle,it is an important means to optimize the combustion of the hybrid dedicated engine,improve the combustion performance,and achieve its efficient combustion.The RCCI combustion mode based on dual fuel injection can effectively improve the engine thermal efficiency,reduce pollutant emissions,and has good control of the combustion phase,but the mode still has certain problems in the expansion of large-load operating conditions.Compared traditional engines with hybrid dedicated engines,the operating conditions of hybrid dedicated engines are narrow,and mainly concentrated in the high-efficiency medium and high load areas,which are suitable for the load conditions of the RCCI combustion mode's stable operation.Aiming at the specific working point of the hybrid dedicated engine,this paper optimizes its combustion by RCCI combustion mode.Combining the vehicle matching and performance simulation,the paper explores the potential of further improving the economy of the vehicle and reducing the emission of original machine pollutants.This paper uses the extended range hybrid vehicle as the research model,and modifie a commercial truck to hybrid vehicle.According to the original vehicle performance design index,the vehicle power system components are matched with parameters.Aiming at the hybrid dedicated engine,this paper adopts the dual operating point constant power control strategy,and selectes the dual target operating point of engine according to the power demand of the vehicle.The operating point A which at medium and high loads uses the RCCI combustion mode for combustion optimization.The optimized performance parameters are used for vehicle matching and performance simulation.The operating point B which under heavy load adopts the traditional compression ignition mode,and its performance parameters are consistent with the original machine.Base on the original engine,this paper designe and develope the engine dual fuel injection system,and built the test and research bench.Aiming at the target operating point A,this work carrys out an experimental study of the RCCI combustion mode based on gasoline/diesel dual fuel injection,and study the effects of three main combustion control parameters,gasoline ratio,diesel injection timing and EGR rate,on engine combustion and emission performance.Under the condition of fixed EGR rate,cross-test the target optimization area of gasoline ratio and diesel injection timing,and find the best matching result of gasoline ratio and diesel injection timing through nonlinear programming optimization.Finally,the target operating point the performance after combustion optimization was compared with the original performance.The research results show that by adjusting the combustion control parameters,the combustion process can take the form of a two-stage combustion.The two-stage combustion is beneficial to shorten the combustion duration and improve the combustion constant volume on the basis of ensuring the combustion stability,which can effectively improve the combustion thermal efficiency;Reasonable combustion control parameters can reduce NOx and particulate emissions at the same time under the premise of ensuring higher thermal efficiency.According to the optimization results of the combustion control parameters,at a fixed 30% EGR rate,set the target working point gasoline ratio to 65%,When the diesel fuel injection time is 14°CA BTDC,the indicated thermal efficiency of the engine reaches 52.5%,which is 7.8% higher than the original engine,12.1% lower than the fuel consumption,and the NOx emission level is reduced to 1/3 of the original engine.The mass concentration emissions are reduced by half compared to the original machine,while the HC and CO emissions are increased due to wall quenching and clearance effects.Based on the vehicle parameter matching results,the vehicle and vehicle control models were built by Cruise and Simulink software,and the performance of the hybrid vehicle after matching the engine operating point optimization was simulated and analyzed.The simulation calculation results verify the rationality of the vehicle parameter matching results;compared to the pure fuel vehicle before the modification,the equivalent fuel consumption of the vehicle under different cycle test conditions can be improved by more than 20%,compared to the target engine work Before the ignition optimization,the equivalent fuel consumption of the vehicle in the C-WTVC cycle test mode extended range mode was improved by 6.66%.