| With the rapid development of my country’s automobile industry and the improvement of people’s requirements for the convenience of life,motorcycles are favored by many people because of their small size,convenient driving and high economy.However,due to the relatively backward technology in related fields in my country,many technologies and performances of motorcycles have not been fully explored.At the same time,due to the related impact of the global energy crisis and the epidemic,my country has a strong demand for independent mastery of core technologies.Combined with the current situation and people’s needs,it is necessary and urgent to optimize the performance of motorcycles and their related components,especially the engine as the "heart" of motorcycles,the improvement of its performance is the most important thing.This paper takes a high-speed motorcycle gasoline engine as the research object,and uses the engine professional software GT-POWER to build a one-dimensional simulation model of the engine.On the premise of ensuring the accuracy and reliability of the model,the model is used to simulate part of the structure and adjustable parameters of the engine,and the influence of each parameter on the performance is analyzed.Finally,using the coupling of Isight and GT-POWER,the dynamic performance and economic indicators of the model are multi-objective optimization work,and the optimization values of adjustable parameters under different loads and speeds are solved to make a MAP map for subsequent optimization.and research work to provide a certain reference role.The contents of this study mainly include:(1)Building a one-dimensional thermodynamic simulation model of the engine,and use the data obtained in the previous bench test to verify the accuracy to ensure that the one-dimensional model can accurately simulate the actual engine performance and serve as the basis for subsequent simulation research.(2)The dynamic performance and economy of the engine are simulated and analyzed by using the calibrated model.Due to the strict sequence relationship between the design parameters of the engine and the adjustable parameters,that is,the compression ratio of the engine and the parameters of the intake and exhaust systems are the design parameters of the engine,and the relationship between them and performance needs to be analyzed in detail at the early stage of design,while Adjustable parameters need to be analyzed on the basis of determining the design parameters,so as to provide an important reference for the calibration and optimization of the engine.Among the many parameters of the intake and exhaust structure,the length of the intake pipe(A),the length of the exhaust pipe(B)and the diameter of the exhaust pipe(C)are the three parameters that have obvious effects on the engine performance.Analyze the impact of these parameters on engine power and economy.Secondly,some adjustable parameters of the engine are simulated and analyzed,including excess air coefficient(lamba),intake valve opening angle(inangle)and exhaust valve opening angle(exangle),and finally the influence law of each parameter is summarized and analyzed.(3)The goal of this research is to improve the power and economy of the engine,and the specific indicators are engine power and effective fuel consumption.Due to the mutual constraints between the two,this paper uses the professional optimization software Isight and GT-POWER co-simulation,and uses the NSGA-Ⅱ multi-objective genetic algorithm to optimize its performance.According to the analysis in(2),the optimization in this paper is divided into two stages:The first is to optimize the engine structure,including the improvement of the compression ratio of the engine and the optimization of the structure of the intake and exhaust pipes.First,the compression ratio is determined to be 12.The length(B)and the diameter of the exhaust pipe(C)are determined according to the actual installation position and space of the engine.The second is to optimize some of the adjustable parameters of the engine after determining the compression ratio and structure,including excess air ratio(lamba),intake valve opening angle(inangle)and exhaust valve opening angle(exangle),and for different The optimal adjustable parameters under the working conditions are solved,and the relevant MAP map is made to provide a reference for the optimal parameters of the engine under different working conditions.(4)In order to compare the performance of the engine before and after the optimization,in the final stage,by simulating the performance before and after the two optimizations under full load conditions,it is found that under the external characteristics,when the speed is from 3000 rpm to 9000 rpm,the performance of the engine is all the same.It has been improved to a certain extent.Among them,in the structural optimization stage,the power is increased the most at 8500 rpm,which is 10.41%,and the effective fuel consumption rate is the most optimized at 9000 rpm,which is 9.31%.Finally,after two optimizations,the maximum power at 9000 rpm is increased by 14.86%,and the effective fuel consumption rate is reduced by a maximum of 9.34%. |
