In recent years, the accuracy of test equipment has been improved continuously, and the development of simulation software is becoming more mature. The research on transmission vibration and noise in China is more in-depth. The noise is reduced by using the method of Guo Xiaoquan and Shi Yuehui. Liu zufei took the fluctuation of transmission error and tooth surface load as the standard, combined with genetic algorithm to modify and optimize the transmission gear, and finally determined that this method had better performance in reducing transmission gear noise. Wang Zhonghou, Zhang Zhengkai and Zhang Liping used Kato equation to calculate the noise level of meshing gear. At the same time, the sound power of transmission gear under different sound sources was studied and analyzed, which provided reference for noise suppression of gear system of transmission. Pan Haibo established the meshing vibration model of the gear when he studied the transmission gear. By using the model, the error was associated with the modification scheme, and the modification curve of the top and root of the gear was finally established, and the impact of the gear meshing was reduced by this method. Through romax software, sun Feiyang analyzed and studied the howling and knocking vibration of transmission gears. Taking the first gear as an example, he optimized the transmission performance of the transmission system. Finally, it proved that the gear modification has a positive impact on the meshing performance and vibration of the transmission gear system.
In addition to gear modification, the research on test and simulation has also made some achievements. With the gradual improvement of test scheme and simulation software, on the one hand, the combination of simulation and test has become one of the important research means, on the other hand, the research on the causes of transmission noise has become more and more mature. On the basis of building the transmission test-bed, Yang Yi and Li Zhiyuan used the order tracking technology to collect the vibration signal of the transmission, and then found the noise source by analyzing the data, which did not provide the basis for subsequent optimization. Lin Juguang and Hu bo used sound field measurement method to test and analyze the vibration and noise of 14 gear transmission of an automobile. Finally, through improving the gear tooth surface defects, the noise source was found and the vibration and noise of the transmission system was suppressed. Liu Zhengjiang, Chen Huan and Li Xinmin put forward the transmission box structure design scheme and mass imbalance theoretical model when they carried out fault diagnosis test on the transmission, and then analyzed the frequency spectrum of the test data to find out the causes of vibration and noise.
Transmission is a mechanical structure composed of many parts. Besides gear and shaft system, the influence ofbox and bearing on assembly noise can not be ignored. When Yu Yinxin, yuan Huiqun, Zhang Liang and Lu Bingwu of Northeast University analyzed the gear transmission system and assembly of a transmission under three gear conditions, according to the modal theory, the time-varying meshing stiffness, transmission error and gear impact of were used as excitation, and the structural mathematical model, damping unit and coupling matrix of the transmission were correlated to obtain the dynamic response model At the same time, in addition to the frequency division, frequency multiplication and modulation frequency, it also shows nonlinear characteristics. This conclusion provides an effective method for the research and analysis of vibration and noise in transmission. When Zhang Jing and others studied the rear bearing of a transmission auxiliary shaft, under different preloads, the dynamic changes of transmission error excitation, meshing force and bearing force were investigated. Combined with the test, it was found that the preload has an important impact on increasing the bearing stiffness and reducing the vibration and noise of the transmission. Liao Fang, Gao Weimin, Wang Cheng and Li Junpeng proposed a new vibration identification technology for transmission case based on modal extension technology, and improved the sound radiation area, and obtained ideal results.
With the gradual improvement of relevant national test standards, automobile manufacturers and research institutions pay more and more attention to transmission vibration and noise. At present, a large number of domestic enterprises have set up vibration and noise related research institutions and departments. Among them, FAW and FAW started the research on vehicle NVH earlier, and their noise test laboratory and noise related research institutions were established earlier. In addition, in 2006, Chongqing introduced head acoustic testing equipment and set up a vehicle laboratory; Foton, Germany, built a vibration and noise test and evaluation system based on LMS related test plates in China. In addition, more and more research institutions have been established through school enterprise cooperation, among which the most representative include the noise and vibration engineering center of Tongji University and SAIC, the vibration and noise Laboratory of Hefei University of technology and Chery.
In general, with the improvement of the test equipment, the degree of combination of test and research is also increasing. Although the research time of local institutions on vibration and noise is shorter than that of foreign countries, it has made great progress in the vibration and noise of transmission, and has gained a lot of valuable experience. At present, for the control of transmission vibration and noise, while the transmission gear modification technology continues to be in-depth research, researchers also began to pay attention to the bearing, housing and new materials.