Research On Matching Design Technology Of Powertrain Mount System Of Commercial Vehicle

Engine is one of the main vibration excitation source in commercial vehicle, which has significant influence of NVH performance. Besides, NVH performance of the powertrain mounting system is regarded as an important part of NVH performance of commercial vehicles. Reasonable matching of the powertrain mounting systems of commercial vehicle not only can reduce the vehicle vibration and noise, and also can improve the ride comfort and the service life of the parts, components and vehicle, at the same time which has become a key problem during the process of the development of high speed and lightweight. Focusing on the research of the matching design techniques in commercial vehicle's powertrain mounting system,I conclude as the following work:Firstly, it illustrates some vibration frequencies that are the most common ones in engine, which has established the range of natural frequencies in powertrain mounting system by combining with engine operation features. According to different incentives due to the variety of cylinders' quantities and engine categories, it has analyzed in incentives of four-cylinder and six-cylinder engine. In addition, Mount arrangement and number is discussed, and the reasonable matching principles of inherent frequency along with energy decoupling theory are also concluded, which is capable of providing the theory basis for establishing the powertrain mounting system models of commercial vehicles and NVH performance matching designs.Secondly, evaluation of the dynamic response of powertrain mounting system with reasonable frequency, decoupling ratio and support reaction force, the six-DOF dynamic model of powertrain mounting system has been established by software ADAMS/View, used for modal and decoupling analysis and tested for MATLAB. Because the vibration isolation performance of the system cannot meet the design requirements, the optimization of powertrain mounting system views the stiffness parameters of powertrain mount system as design variable, and the reasonable matching of natural frequency as constraints, and the energy decoupling as objective. Through the integration of Isight with Adams/View, the powertrain mount system is optimized and analyzed. The result showed vibration isolation performance of the powertrain mount system was significantly improved. By comparing before and after NVH performance of the optimization of the powertrain mount system, it verifies the correctness of the deterministic optimization.Thirdly, in that the mounts' stiffness fluctuation is easily affected by rubber materials, amount of interferences and so forth, it discusses its impacts to NVH performance of the powertrain mount system. According to the robust optimization theory, considering the influence of powertrain mount(e.g., materials, manufacturing, processing, measurement, etc.) to NVH performance, it gives a robustness analysis to the optimized system. In order to improve the robustness and reliability of the system, stiffness as normal distribution random variables, the reliability and robustness of the system are greatly improved, thereby which reducing failure probability of the system.Finally, this thesis introduces the method of nonlinear mounts' stiffness, combined with practical engineering case, for a six-point powertrain mount system of heavy truck, whose nonlinear stiffness curve is designed, in the ADAMS software to establish the simulation model, using GMW14116 standard condition for the corresponding conditions of load, and then the displacement of center of gravity of powertrain meets the design requirements. In the last, it is obtained the mount load and displacement at the same time, in order to be further used for checking the strength of the mount bracket and fatigue analysis provided the basis.