Identification Analysis Of Powertrain Abnormal Vibration And Noise Of Vehicle With Longitudinal Engine

Automotive powertrain is the key part of the automobile, including the engine, transmission and so on. Powertrain’s vibration and noise is an important factor to influence the vibration and noise performance of the automobile. For improving vehicle NVH performance, it is an important premise to master the key technology of NVH analysis and optimization design of powertrain.The sound-vibration test was carried out aimed at identifying abnormal vibration noise of transmission system found in NVH performance test in a MPV with longitudinal engine. The method of order analysis based on noise and vibration tests was employed to identify the abnormal vibration and noise sources of powertrain system, and the mechanism of noise was also investigated. Based on the results, simulation models for parts that caused noise were established. A precise dynamic model for transmission that caused noise was established with ROMAX software, and the inherent characteristics and dynamic response characteristics are analyzed based on the model. A noval evaluation index for gear rattle was proposed. The input excitation of gear rattle was acquired by calculating the output torque fluctuation of engine. The torque fluctuation was got by taking advantage of actual engine cylinder pressure under various engine speeds, the index of different speeds was discussed and verified. Furthermore, from the angle of improving the transmission error of the gear, the macro parameters and microscopic practice parameters of the gear were optimized and analyzed. The analysis results are match to the experimental data. Based on ADAMS software platform, a dynamic model for mounting system was established, combined with experimental data, natural frequency, energy decoupling rate and the amplitude change of steady dynamic force of mounting system are analyzed. With the optimization objective of reasonable arrangement of natural frequency, promoting decoupling rate and the vibration isolation effect under specific speed, the structure parameters and stiffness parameters of mounting system were optimized. The correlation analysis results are in agreement with the experimental data.The results show that the identification analysis method of abnormal vibration noise of transmission system is reliable, which can provide reference for the NVH analysis of similar models.