| The main advantages of double helical gear transmission contain high transmission efficiency, compact structure, high loading capacity as well as low bearing axial load which make it widely used in aerospace, industrial and marine ships. The vibration and noise problems of the system are serious due to the complicate structural parameters and working conditons as well as the various forms of the internal excitations. And it will be difficult when considering tooth friction in the dynamic analysis of the double. Based on the above, launching the dynamic analysis of the double helical gear transmission considering tooth friction has great significance. This paper mainly works in four aspects: the analysis of tooth friction excitation, the dynamic analysis of the double helical gear pair, the establishment of the dynamic model of the double helical planetary gear as well as the dynamic analysis of the double helical planetary gear train.In the analysis of the tooth friction excitation, the difference of the coefficient of friction under different model has been compared. The result shows the coefficient of friction based on EHL theory is more close to the reality.The characteristics of the contact line are analyzed based on the meshing process analysis of the double helical gear pair. The meshing force and the friction force as well as the friction torque have been calculated by numerical integration(NI).In the analysis of the dynamic characteristics, a three-dimensional nonlinear dynamics model of the double helical with sixteen degrees has been established. The model takes the sliding friction, time-varying stiffness, gear backlashes as well as gear mesh errors into account. The dynamics equations of the system are established by Newton second law. The effects of tooth friction on the dynamics behaviors of the system are studied. The results show that the sliding friction can increase the vibration in the perpendicular direction to the line of action but suppress the vibration in the line of action. The bifurcation of the system becomes blurred at the high meshing frequency and chaotic motion appears earlier as well as infirmly due to effect of tooth friction.In the dynamic modeling of the double helical planetary gear sets, a new dynamic model of the double helical planetary sets considering the axial vibration of the gear is established. The transformation from the absolute coordinate to the relative coordinate has been implemented. The coordinate condition of elastic deformation between the meshing pair and the time-varying mesh stiffness as well as the tooth errors are analyzed. The dynamics equations of the system are derived by Newton second law.The operation of removing the rigid mode as well as the identical dimensionless are conducted to derive the identical dimensionless dynamics equations of the system.In the analysis of the dynamic characteristics of the double helical planetary gear sets, the effect of the tooth friction on the periodic vibration and the nonlinear vibration of the system are analyzed. The results showed that the bifurcation of the system becomes blurred at the high meshing frequency. And the tooth friction will increase the power loss of the system, which changes the vibration of system from chaotic state to periodic state. |
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