Powertrain's Vibration Isolation Design And NVH Optimization Of A SUV

With the progress of science and technology and improvement of people's living condition, vehicle NVH(Noise?Vibration and Harshness)performance attract more and more attention, which become one of evaluation indexes when customers buy a car.How to reduce vibration and noise effectively become a important in design of automobile. Therefore, designing automobile powertrain mount system reasonably has important engineering and practical value. It can not only improve the performance of auto NVH but also avoid damage in other parts of suspension system resulting from unreasonable powertrain system, prolong the service life of the engine. This paper focus on matching and optimization design of powertrain mount system for a SUV. NVH testing and analysis are also conducted for the whole vehicle.Matching design of stiffness for a SUV powertrain mount system in development are conducted, results show that the decoupling rate of powertrain mount system of mule car is generally low. In order to get the best performance of vibration isolation, based on energy decoupling method combined with multi-body dynamics and genetic optimization algorithm, dynamics model of powertrain mount system is established in the Adams, stiffness is selected to be variable parameters, natural frequency distribution are taken as design constraint, decoupling rate in 6 DOF is assigned as the optimizing objective. Integrated Isight with Adams, stiffness parameters of the powertrain mount system is optimized to meet the requirements of the vehicle noise reduction and vibration isolation.The working condition of the powertrain mount system are analyzed by using GM 28 working standard, load at each powertrain point is obtained by si mulation, which is input condition to check bracket's strength design. Model analysis and static strength analysis is undertaked for the 4 mount bracket to check modal frequency and strength whether meet the design requirements by using abaqus. Put forward the corresponding optimization suggestions for mount bracket that don't meet the requirements according to the simulation results, and finite element analysis is conducted for optimized mount bracket.In order to verify performance of vibration isolation of powertrain mount system after the parameters matching and optimization, test on powertrain vibration and vibration isolation rate of powertrain mount system of vehicle with OTS sample is carried on. In 800 ~ 3100 rpm speed and frequency range of 0 ~ 200 hz conditions, vibration in the mount bracket side,in the engine side and vibration isolation rate is analyzed. According to the results of test and analysis, the mount is optimized. The NVH property of vehicle with optimized powertrain mount system is tested. The consequence is compared with state before the optimization to check NVH performance of optimized system.