Optimal Design Of The Powertrain Mount System In Medium Electric Bus

When dealing with the battery, motor, electronic control system, charging infrastructure and other problems of electric vehicles, we also need to improve the NVH performance of vehicles. Since the drive motor replaces the engine, the “masking effect” of the engine disappears, which has brought new challenges to the noise control of electric vehicles. The powertrain mount system is an important subsystem of the electric vehicle vibration system, whose vibration transfer characteristics have a great impact on the ride comfort and noise quality of an electric vehicle. Therefore, this paper combines with the school-enterprise cooperation project “Medium electric bus design and development”, mainly aimed at designing and optimizing the powertrain mount system of the electric bus.First, the basic theory of isolating vibration and the basic principles of mount system design are introduced, the operating characteristics of suspension elements are then analyzed, on this basis, combined with the actual arrangement space and working environment of the motor powertrain, the initial layout plan of the electric bus motor powertrain mount system is made. Also, the incentives of the system are analyzed.Second, the 6-DOF rigid body dynamics model of the motor powertrain mount system is established, through the Lagrange Equation, the differential equations of the mount system are deduced. The parameters of the mount system are then measured and determined. With the use of software ADAMS, the virtual prototype model of the motor powertrain mount system is built.Then, based on the analysis of the incentives, the simulations on modal, frequency response, time domain response of the motor powertrain mount system are conducted by ADAMS. From the analysis results of the simulations, it is found that the energy decoupling rate of the mount system needs to be improved and transient impact load of the suspension elements is uneven, which indicates that it is necessary to conduct the optimal design of the mount system.Finally, the motor powertrain mount system is optimized by integrating software Isight and MATLAB. The weighting sum of energy decoupling rate in six degrees of freedom is chosen as optimization goal, the spindle stiffness values of the respective suspension elements are set as design variables, the reasonable distribution of system natural frequency and the upper and lower boundaries of design variables are set as design constraints. The lower-sensitivity variables are excluded by sensitivity analysis. The design variables are optimized with MIGA, the contrast analysis is conducted between the original and optimized design, results show that the optimized design has achieved the effect of vibration and noise reduction. The robustness test is implemented in the certainly optimized mount system by Monte Carlo method, whose results show that the robustness of the optimized mount system is enhanced to meet the engineering requirements.