Energy and environmental problems are becoming increasingly serious, and new energy vehicles have attracted much attention. Electric vehicles have become the focus of research in various countries because of their advantages of zero emissions, low noise, extensive power sources and so on. There are many similarities between electric vehicles and fuel vehicles in body structure, but there are significant differences in the structural form of power transmission system and service environment. The transmission system of electric vehicle omits torque converter, clutch and other torsional vibration damping components, and the system is an underdamped system; At the same time, the transmission system adopts the structural form of multi-stage deceleration and few gears, which makes the power transmission path shorter and the number of cycles significantly increased. These new characteristics of electric vehicle transmission system have brought new theoretical and technical problems. Among them, the life prediction and system reliability of transmission system are the bottlenecks that restrict the further improvement of its performance.
Taking the high-speed cylindrical gear of an electric vehicle with a fixed transmission ratio as the research object, the control model of the vehicle permanent magnet synchronous motor is established, and the dynamic output torque of the motor under the cycle condition is obtained by simulating the model based on the cycle condition (UDDS); Taking the dynamic torque of the motor as the driving torque of the cylindrical gear, the contact stress spectrum of the cylindrical gear pair under cyclic conditions is obtained; The rain flow counting method is used to count the contact stress spectrum of cylindrical gears, and the amplitude frequency relationship of contact stress of high-speed cylindrical gears under cyclic conditions is obtained.
Based on the dynamic control model of vehicle permanent magnet synchronous motor and cycle driving conditions, the contact stress spectrum of cylindrical gear under cycle conditions is obtained by computer simulation, and the rain flow counting method is used for counting and statistical analysis, and a more accurate distribution law of contact stress of cylindrical gear is obtained, which overcomes the defect of low calculation accuracy caused by the empirical assumption of load distribution law, The accuracy of system reliability calculation is improved, which provides a basis for further establishing the dynamic reliability model of electric vehicle transmission system.