Vibration Analysis Of Electric Vehicle Twospeed Automatic Transmission Under High Speed Condition

As a key component in the transmission system of electric vehicles,transmissions have always been a research hotspot in the industry for the vibration and noise generated during their operation.For electric vehicle transmissions,due to the high integration and high speed of the system,obvious NVH problems are prone to occur under certain working conditions,which seriously affects the driving comfort of the driver.In the early stage of the development of the industry,due to different technical requirements,the operating conditions of traditional fuel vehicles are generally lowto-medium speeds.This has led to the current research on transmission vibration and noise issues mostly under low-to-medium speeds.However,there are few studies under high speed conditions.Therefore,this subject conducts in-depth research on the vibration characteristics of a brand of electric vehicle two-speed automatic transmission under high-speed operating conditions.The main research work of this paper is as follows:(1)According to the working principle of the transmission,the transmission diagram was drawn,and the three-dimensional model of the transmission was constructed by PREO software.Then,the dynamics simulation analysis of the transmission system was carried out by ADAMS software.At the same time,in order to ensure the accuracy of the simulation data,the internal shafting structure of the transmission system was processed flexiblily.Thus,the rigid-flexible coupling dynamics model of the transmission system was constructed.The simulation results obtained the dynamic meshing forces of each gear tooth in the transmission system and the dynamic supporting reaction forces of each bearing point,which provided data support for the subsequent dynamic response analysis and vibration test of the transmission box.(2)The dynamic characteristics of helical gear meshing under the action of rodent impact were analyzed.According to the mechanism of rodent impact,the impact velocity and impact force generated in the impact process were deduced,and the curve of its change with time,speed and load was plotted,and the bending-torsion-axial coupling dynamics model of single-stage helical gear transmission was built.The vibration response of the system under different speed excitation is obtained.(3)The modal analysis of the transmission was carried out through modal simulation technology,and the natural frequency and mode shape of the transmission were obtained by solving the solution.At the same time,the transient dynamics analysis was carried out on the box body of the transmission,and the dynamic support reaction force of each bearing point was regarded as the exciting force and applied to the box housing.The dynamic response of vibration acceleration,vibration velocity and vibration displacement of each test point in the gearbox body is obtained.(4)through the study of the vibration test of the transmission experiment,obtained the gearbox housing surface vibration acceleration response of each test point by comparing the experimental data and simulation data and found errors are within 10%,the test results and simulation results have good consistency,the finite element model to verify the accuracy and reliability of simulation results.At the same time,the vibration tests of the gearbox under different speed conditions were carried out.The results show that when the speed exceeds 7000 rmp,the amplitude of vibration acceleration increases significantly,which will have a great impact on the stability of the system.At the same time,this conclusion also has important engineering application value for vibration analysis,structural design and lightweight research of transmission.