Research On Dynamics Of Herringbone Planetary Gear Based On Tooth Surface Friction

The subject comes from the National Natural Science Foundation of China ’s project’ Research on Transient Contact Characteristics and Anti-gluing Loading of Human Planetary Gear Transmission(project approval number:51975078)and the subproject of the National Key Research and Development Plan ’s project ’ Degradation Mechanism and Life Prediction of Gear Service Performance(project approval number:2018YFB2001302).As a new type of high power density transmission system,herringbone planetary gear transmission has higher load-bearing performance and lower axial impact load than spur and helical planetary transmission,and has the characteristics of smooth transmission and compact structure,is used in major transmission equipment fields such as mining equipment,aviation,ship transmission and so on.However,due to the complicated structural design of the herringbone planetary gear transmission system,the time-varying and non-linear internal excitation,and the variability and complexity of the service conditions,the system produces inevitable problems such as vibration and noise during operation.If the influence of non-linear tooth surface sliding friction excitation is considered,the dynamic characteristics of the transmission system will be more difficult to predict.This paper is based on the scientific research tasks of the National Natural Science Foundation of China and the National Key R&D Project undertaken by the research group,and aims to achieve the long-term service,high loadbearing capacity and low noise of the herringbone planetary gear system.The dynamic characteristics and coupling friction characteristics of the herringbone planetary gear transmission are studied,and the influence mechanism of the sliding friction excitation of the tooth surface and different working conditions on the above characteristics is analyzed.It provides a theoretical reference for the optimization and improvement of the herringbone planetary gear transmission system and engineering applications.The specific research content is as follows:(1)According to the structural characteristics of the herringbone gear pair,the two sides of the herringbone gear pair are divided into several slices along the tooth width direction respectively,and they are regarded as a series of staggered spur gears without considering the elastic coupling.Then,the time-varying meshing stiffness of the entire single-sided internal and external gear pair is obtained by integrating along the surface width.The calculation formula of the time-varying meshing stiffness of the inner and outer meshing pair is analyzed and deduced.The numerical simulation solution is compared with the finite element simulation solution to prove the reliability and accuracy of the stiffness model in this chapter.The influence mechanism of time-varying stiffness of external meshing gear pair.(2)Under the premise of considering different input torque,input speed and tooth surface micro-shape,based on the theory of hybrid elastohydrodynamic lubrication,the herringbone planetary gear is modeled and analyzed,and the time-varying contact line,dynamic friction coefficient,dynamic friction coefficient of the herringbone gear pair are analyzed and deduced.Calculation formulas for dynamic friction force and dynamic friction torque.The hybrid elastohydrodynamic lubrication model of the herringbone planetary gear is simulated and analyzed by the multi-grid method,and compared with the results of related literatures,so as to verify the correctness of the hybrid elastohydrodynamic lubrication model in this paper.The experimental test on the rough surface of the gear teeth has passed many tests.A group of experiments fit different tooth surface roughness,and optimized the empirical formula of the center oil film thickness to make it suitable for gear teeth with different microscopic appearances.Finally,the change mechanism of different input torque,input speed and tooth surface roughness on dynamic friction coefficient,single-tooth friction,single-tooth friction torque,three-tooth friction and three-tooth friction torque along the meshing line is discussed.(3)Considering time-varying meshing stiffness excitation,sliding friction excitation,meshing phase of internal and external meshing pairs,tooth profile error,etc.,based on the lumped parameter method,the dynamic modeling of the herringbone planetary gear dynamics model,each component in the model has a total of 60 degrees of freedom(Translational vibration,vertical vibration,axial vibration,axial torsion).The RungeKutta method is used to solve the numerical simulation of the herringbone planetary gear system,and then the vibration characteristics of the sun gear,the ring gear,the planet gear and the planet carrier in each degree of freedom are obtained.And study the influence of different sliding friction excitations on the dynamic characteristics of the system from the two angles of time domain and frequency domain.(4)Firstly,the hybrid elastohydrodynamic lubrication model and the herringbone planetary gear dynamics model are integrated,and then the friction-herringbone planetary gear dynamic model containing dynamic coupling characteristics is obtained.Secondly,the dynamic characteristic response of the herringbone planetary gear friction dynamics model is jointly iterated.Solve.Finally,the meshing frequency is used to scan the dynamic characteristics of the system under different parameters in the frequency domain,and then the influence of different parameters(tooth surface roughness,input torque and input speed)on the dynamic characteristics and friction characteristics of the system dynamics model is studied,which is a herringbone Planetary gears provide theoretical reference for vibration and noise reduction under variable service conditions.