| Transmission is an important part of the automotive driveline, whose structure affects the vehicle dynamics, fuel economy, riding quality and efficiency directly.In recent years, with the high-torque and high-speed designing of automotive engines, more and more requirements were given on the capacity and reliability of the transmission. Being one of the most important indicators of the performance, transmission structural vibration and noise are taken more and more attention. So how to reduce the noise and improve the gear strength has become an important research subject currently. Comparing to involute gear, the fine-pitch gear is one of small modulus and large addendum coefficient to make the gear tooth thinner and higher. So using fine-pitch gear is the most effective way to attain high strength and low noise.In this paper, the gear’s strength, life and natural frequency will be obtained by analysing the TY fine-pitch gear transmission which is primary and secondary box combined, and the analysis is verified by experiment.The main work of the thesis is as follows:1) Multi-body dynamics theory of gear is analysed, and on this basis, the fine-pitch gear transmission model is build by Romax Designer software. Because only one range or synchronous can be set one time in the simulation of Romax, it’s impossible to hang two gears in the main and vice box at the same time. So it is need two model to enable the transmission change the range from1to10, which only differ about the transmission line.2) Steady-state analysis of transmission model is carried out. The results of the fatigue life of simulation can simulate the results of the fatigue life of experiment well, which is also verified by formula. A new simulation with normal torque and time is worked based on results above, and the results indicate the transmission is safe. In addition, by modifying the tooth profile, the load per unit on the tooth surface decrease and the gear life increase.3) The mode of the fine-pitch gear transmission is also analysed in this paper, and the results of natural frequency between hammering test and simulation are almost the same. And then using the spectrum validates the correctness of the results above when the input speed is1300r/min. It also analyses the inherent characteristics when the input speed is2200r/min, and predict the potential frequency and block under which the vibration may occur. Finally, by analysing the Campbell diagram, the potential frequency and block causing vibration in the entire speed range of the transmission is obtained. |
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