| The requirements for its stability are also gradually improved with the continuous improvement of the speed of high-speed EMU train(high-speed railway).Gearbox is the main factor affecting the train stability,as the core transmission component of EMU train.Helical gear is widely used in EMU train gearbox,because the large coincidence degree,the load acting on each pair of gear teeth is relatively reduced.the phenomenon of tooth rattling will directly affect the stable operation of high-speed EMU train,due to the influence of tooth backlash,in the actual meshing process of helical gear of high-speed EMU train.In order to explore its causes and its impact on the stability of helical gear transmission,this dissertation studies as follows.Firstly,the multi-state meshing characteristics of helical gear pair are studied by the meshing principle of helical gear pair.The complete 3-2-3-2-3 meshing process of helical gear driving wheel is analyzed from tooth root to tooth top.Secondly,the time-varying meshing stiffness of helical gear pair is solved by using the cumulative potential energy method,and the time-varying load distribution rate is solved by solving the ratio of each pair of tooth contact lines to the total contact lines in the meshing plane.Thirdly,the torsional vibration equation of helical gear pair and five multi-state dynamic models are established along the meshing line under the joint action of coincidence degree and tooth backlash.The dynamic characteristic transition process of the system(cover the torque,error,frequency,backlash)is analyzed.According to bifurcation diagram,phase portrait,Poincaré map and top Lyapunov exponent(TLE)diagram base on the calculation of these parameters by fourth-order lung Kutta method.The relationship between meshing force and meshing state is analyzed during the transition of helical gear motion state by the time history diagram of meshing forceThe research results of this dissertation can provide a theoretical basis for revealing the dynamic transition behavior of helical gear pair considering multi-state meshing characteristics,and can also provide a theoretical basis for the design and selection of helical gear parameters. |
