| Planetary gear transmission is widely used on the transmission mechanism of various high-speed heavy equipment because of its large carrying capacity, high transmission efficiency, high transmission ratio, etc. Closed differential planetary gear drive is a common structure form of multi-stage planetary gear drive. Compared with general planetary gear drive, the structure of closed differential planetary gear drive is more compact. Therefore, the carrying capacity of closed differential planetary gear drive is larger. Products of closed differential planetary gear reducer designed by our country are not found on the market currently. In order to break the foreign monopoly on large high-speed heavy transmission equipment and improve the competitiveness of China’s machinery products, closed differential planetary gear reducer is studied in this paper. Based on a lot of relevant literature reading and theoretical study, preliminary structural design and simulation research are conducted using traditional design methods and modern analytical tools. Main work contents of this paper are as follows:(1) Structure parameters of main components in the closed differential planetary gear reducer are calculated by the use of traditional design theory. Strength check of tooth surface contact and tooth root bending are conducted for tooth surface and tooth root which are easily damaged in gear meshing. Besides, strength check is also conducted for flexpin which is the core component in the system. Finally, a three-dimensional model of the planetary gear reducer is established according to the calculated structure parameters.(2) Using multi-body dynamics analysis software ADAMS, kinematics analysis is conducted on the imported three-dimensional model of planetary gear reducer. The transmission ratio obtained by simulation is compared with the theoretical value. The two values are the same. Multi-rigid-body dynamics analysis is conducted after constraints are modified. The obtained meshing forces of gear meshing pairs are compared with the theoretical value. Fluctuations can be seen on the simulation results. They are caused by different meshing force on different meshing position and the impact of meshing. (3) Static finite element analysis of flexpin on second-stage planetary gear transmission, which carries larger load, is conducted using finite element analysis software ANSYS. Besides, three-dimensional finite element contact analysis of planetary gear and sun gear meshing pair on the first-stage, whose stress value is large in theoretical calculations, is conducted. All the simulation results can meet the corresponding strength requirements.(4) The elastic deformation of flexipin, which is the key component of the system, is considered based on the multi-rigid-body dynamics analysis. Flexible processing is conducted using finite element analysis software ANSYS. The modal neutral file obtained is imported into ADAMS for rigid-flexible coupling dynamics simulation. Flexible body stress nephogram of flexpin is obtained. The maximum stress is slightly larger than that of static finite element simulation but still much smaller than the allowable stress. Results of meshing force in rigid-flexible coupling dynamics simulation are compared with results of multi-rigid-body dynamics simulation. Fluctuations of meshing force using rigid-flexible coupling model are much smaller than fluctuations of meshing force using multi-rigid-body model.The peak load of gear contact is effectively reduced because the integrated flexpin bearing is used in closed differential planetary gear reducer. Compared with the general planetary gear reducer, the carrying capacity of closed differential planetary gear reducer is larger. The design and simulation methods of closed differential planetary gear reducer are introduced taking performance parameters of planetary gear reducer which is widely used in the heavy equipment at home and abroad as an example. A foundation is laid for further study and actual production of this kind of products. |
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