| Dual clutch automatic transmission has the advantages of high transmission efficiency,simple structure and cheap price of manual transmission.At the same time,it also overcomes the disadvantages of power interruption during manual gear shift,and has become a hot spot in the field of vehicle transmission research.This paper is based on the research task 2 "Research on the Dynamic Characteristics of DCT System under Internal and External Incentives" of the key project of the National Natural Science Foundation of China "DCT Intelligent Control and Evaluation Method Considering Dynamic Service Performance and Driving Behavior and Driving Environment",Combined with the research demand of the longitudinal dynamic performance of the DCT vehicle started and shifted by the powertrain mounting proposed by the enterprise,the research of this master’s thesis was carried out,and the DCT vehicle dynamic model considering the powertrain mounting was established.The longitudinal dynamics simulation analysis of DCT vehicle starting,shifting and typical working conditions is studied,and the influence of mounting stiffness and damping on the longitudinal dynamics of DCT vehicle is studied,which provides the relevant theoretical basis for the development of DCT vehicle.The main research work of this article are:(1)DCT vehicle dynamics modeling considering powertrain mounting.First,the engine numerical model was established based on the engine bench test data provided by the enterprise,and the dual clutch transmission model was established based on the DCT structure and clutch working principle.On the basis of the above model,a DCT vehicle dynamic model without mounting is established as a benchmark for comparing the DCT vehicle dynamic model with mounting;In view of the shortcomings of the existing research that did not consider the impact of mounting in the study of DCT vehicle start-up and shift performance,this paper established a three-degree-of-freedom model of the powertrain mounting system according to the layout position and method of mounting;By analyzing the interaction relationship between the powertrain mounting system and the DCT vehicle,a DCT vehicle dynamic model considering the powertrain mounting is established.(2)Research on the influence of powertrain mounting on DCT longitudinal dynamics when starting.On the basis of the established DCT vehicle dynamics model considering powertrain mounting,a dynamic analysis of the DCT vehicle starting process was carried out,based on the MATLAB/Simulink platform,the starting process of the two models(with mounting and without mounting)is simulated and compared.The results show that in the starting process,when considering the influence of mounting,the vehicle’s longitudinal acceleration will obviously generate additional harmonics.This result is in agreement with the experimental results of the vehicle enterprise,which verifies the correctness of the dynamic model.At the same time,the simulation analysis of the influence of the mounting stiffness and damping on the longitudinal acceleration of the vehicle at the start of the vehicle,the results show that:as the mounting stiffness increases,the additional harmonic frequency of longitudinal acceleration accelerates;as the mounting damping increases The amplitude of the additional harmonics of longitudinal acceleration is reduced;if the mounting stiffness and damping are increased at the same time,the longitudinal acceleration of the vehicle tends to be the same as when the mounting are not considered.(3)Research on the influence of powertrain mounting on DCT longitudinal dynamics when shifting.In the process of vehicle upshift and downshift,the dynamic analysis of the DCT vehicle dynamic model with mounting is carried out,and the simulation comparison analysis of the upshift and downshift processes with and without mounting dynamic model.The results show that when considering the influence of the powertrain mounting during the up and down gears between the first gear and the second gear,additional harmonics will be obviously generated in the longitudinal acceleration of the vehicle;In the upshift and downshift gear process between the middle and high gears,the mounting of the powertrain has little effect on the longitudinal acceleration of the vehicle.Simultaneously,the influence of mounting stiffness and damping on the longitudinal acceleration of the vehicle during the process of first gear up to second gear is simulated and analyzed.The results show that as the mounting stiffness increases,the additional harmonic frequency of longitudinal acceleration accelerates;as the mounting damping increases The amplitude of the additional harmonics of longitudinal acceleration is reduced;if the mounting stiffness and damping are increased at the same time,the longitudinal acceleration of the vehicle tends to be the same as when the mounting are not considered.(4)Research on the influence of powertrain mounting on DCT vehicle longitudinal dynamics under typical working conditions.The dynamic model considering mounting is used to simulate and analyze the acceleration,deceleration and Tip-in/Tip-out conditions of DCT vehicles,and the results are compared with those without mounting.The results show that under acceleration and deceleration conditions,the influence of the powertrain mounting on the longitudinal dynamics of the vehicle is small,and under Tip-in/Tip-out conditions,additional harmonics will be obviously generated in the longitudinal acceleration of the vehicle.Simultaneously,under the Tip-in working conditions,the influence of mounting stiffness and damping on the longitudinal acceleration of the vehicle is analyzed.The results show that as the mounting stiffness increases,the additional harmonic frequency of longitudinal acceleration accelerates;as the mounting damping increases The amplitude of the additional harmonics of longitudinal acceleration is reduced;if the mounting stiffness and damping are increased at the same time,the longitudinal acceleration of the vehicle tends to be the same as when the mounting are not considered. |
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