Instantaneous Mesh Excitation Modelling And Dynamic Response Study Of Planetary Gears With Eccentricity Error

Planetary gears are widely used in automobiles,ships,wind power,aerospace,and other fields due to their advantages such as compact structure and high-power density.With the development of science and technology,strict requirements such as high speed,large load,low vibration,and long service life are put forward for planetary gears.However,factors such as the eccentricity error generated during the machining and installation of the planetary gears and the deformation of the gear support bearings of the transmission system during the loading process and other factors will change the spatial position of the central components of the planetary gears,which will deteriorate the load sharing condition between the planets under heavy load and high-speed conditions,and then induce the tooth surface failure,reduces the service life of the system and aggravates the vibration and noise of the system.It affects the product quality and service performance,and increases the difficulty of the design and development of the high-performance gear transmission system.Therefore,the study of dynamic modelling of planetary gears under eccentricity error,the analysis of the mapping relationship between eccentricity error and meshing excitation,and the investigation of vibration characteristics and load sharing characteristics under eccentricity error can provide theoretical reference for the design of high-performance and high-quality planetary gear transmission system,which has significant science value and engineering significance to ensure the safe operation and fault diagnosis of mechanical systems.Aiming at the problem of instantaneous meshing excitation modelling and dynamic response analysis of planetary gears under eccentricity error,this project starts with the influence mechanism of gear tooth deformation,eccentricity error and bearing radial deformation,carries out the instantaneous meshing excitation and dynamic modelling of planetary gears under eccentricity error,and analyze the influence mechanism of eccentric error,supporting bearing radial deformation and other factors on the meshing excitation and dynamic response of planetary gears,and investigate the vibration and load-sharing characteristics of planetary gears under eccentricity errors.The main work of the thesis includes:1.Aiming at the problem of complex load sharing between tooth pairs and tooth deformation induced by the interaction between tooth deformation and the instantaneous meshing position of the gear pair,an iterative method of vector displacement under the action of the gear tooth deformation is proposed based on the idea that the load affects the interaction between the instantaneous meshing position and the tooth deformation.The instantaneous meshing position and the equations of the tooth pair separation distance,load sharing mechanism and deformation coordination at the instantaneous meshing position are deduced based on the above iterative method Then a mesh stiffness calculation model based on the coupling effect between the instantaneous meshing position and tooth deformation is proposed,which improves the calculation accuracy of mesh stiffness,breaks the shortcomings of the traditional stiffness model to study the corner contact of the planetary gears and further provides a basis for accurately analyzing the dynamic response of planetary gears under different service conditions.2.Aiming at the problem that the change of the relative geometric position relationship of the components under the eccentricity error of the planetary gears induces the corner contact and the change of meshing phase,and further affects the mesh excitation,the analytical expressions of the instantaneous meshing position,the tooth pair separation distance and the meshing phase of planetary gears are derived based on the relative geometric position relationship and motion relationship of the components under eccentricity errors.Then the mesh excitation model of planetary gears with eccentricity errors is established considering the effects of the corner contact and the meshing phase,which reveals the effect mechanisms of eccentricity errors and pinhole position errors on the mesh excitation and load sharing characteristics,and further provides a theoretical reference for accurately predicting the dynamic characteristics of planetary gears under eccentricity errors.3.Aiming at the problem of mesh excitation modelling caused by the change of the central component spatial position of the planetary gears caused by the bearing radial deformation during the operation of the planetary gear transmission system,the geometric relationship and meshing law of the planetary gears before and after the bearing radial deformation are analyzed.Then,the analytical expressions of the instantaneous meshing position and the tooth pair separation distance after bearing radial deformation are deduced.The change characteristics of mesh stiffness under the coupling effect between bearing radial deformation and instantaneous meshing position are investigated based on a numerical iterative algorithm,and the influence of bearing support stiffness on the tooth pair separation distance,mesh excitation and load sharing characteristics of planetary gears are revealed.4.For the prediction problem of the dynamic response of planetary gears considering the coupling effect between the gear dynamic meshing force,the bearing radial deformation and the instantaneous meshing excitation,an iterative algorithm,which can predict the dynamic response and the instantaneous meshing excitation of planetary gears,is proposed.In this iterative algorithm,the dynamic model of planetary gears is established based on the instantaneous meshing excitation,which is deduced by the change of the central component spatial position caused by the gear dynamic meshing force,eccentricity errors and bearing radial deformation.The nonlinear dynamic equations of translation-torsion of planetary gears are derived by the force condition analysis of each component of the planetary gears.Then,the effects of eccentricity error,bearing support stiffness and dynamic response of planetary gears are studied.5.By building a planetary gear eccentricity error experimental bench,the vibration characteristics of planetary gears with eccentricity errors were measured at different speeds,and the effect of eccentricity error of planets on the vibration characteristics of planetary gears was analyzed.The validity and correctness of the dynamic model of planetary gears based on instantaneous meshing excitation were verified by comparing the experimental results with the theoretical results.