Coupling Dynamics Of Planetary Gear Transmission System With Meshing Beyond Pitch Point And Experimental Verification

The planetary gear transmission system can effectively split power using multiple planetary gears. Its input shaft is concentric with output shaft. Such system has many advantages compared with the fixed axis gear train, such as bigger transmission ratio, higher load capability, higher transmission efficiency etc. Thus, it covers many important industrial applications. For the gear drive with meshing beyond pitch point, its actual mesh line is located in one side of the pitch point avoiding the shock vibration caused by the changing direction of friction, which leads to better vibration performance than ordinary gear train. For a more comprehensive understanding of dynamic characteristic of this planetary gear transmission system, this paper analysed its coupling dynamics, the specific contents are as follows:(1) The relationship between radical load and deformation for a ball bearing based on the Hertz contact theory was introduced. Then the formulas of time-varying support stiffness of bearings were derived from this relationship. The contact simulation of bearings was completed by using ANSYS Workbench, the simulation results and theoretical analysis solutions were compared.(2) The coupling relationship between the gear and the bearing was established according to the time-varying support stiffness, and then a more sophisticated dynamics model of planetary gear transmission with meshing beyond pitch point was established using the lumped-parameter method. The meshing stiffness, damp and friction were analyzed. The motion differential equations were derived depend on Newton's laws of motion and then the solution of the equations was discussed.(3) The dynamic responses of the system as well as time-varying stiffness of bearings were obtained by using Runge-Kutta method, and then the influence law of time-varying support stiffness on vibration characteristics of the system was discussed. For an intuitive grasp of the operational characteristics of the system, a motion simulation was completed by using ADAMS.(4) The verification experiment was completed on a 1000 k W mechanical power closed test rig. The testing scheme was adopted and the vibration signals were measured under different working conditions.The signals were analyzed based on the wavelet theory. The theorical anaysis was finally well verified by the denoised signals.