Research On Dynamics Of High-speed-ratio Planetary Gear Transmission Adopting Design Of Low-loss Gears

It is required to achieve high speed ratio in many gear transmission systems,such as coal mining machines and wind turbine gear transmission.NGWN(?)planetary gear transmission possesses high speed ratio ranging from 50 to 500,as well as advantage of compact structure and a low number of components and parts.However,the efficiency of this kind of gear transmission is low,which have hindered its widespread application.This project is the important component of 4th task of The National Major Basic Research Program of China(973 Program,Grant No.2014CB046304).Focusing on the NGWN(?)high-speed-ratio planetary gear transmission and on the basis of analyzing the current research situation at home and abroad,the main research work of this paper is as follows.(1)The pure torsion dynamic model of NGWN(II)planetary gear transmission is established by the lumped parameter method.Firstly,the inherent characteristics of NGWN(II)planetary gear transmission are studied.The natural frequencies and modes of the transmission system are obtained by solving the eigenvalue problem of undamped free vibration equations,and the vibration modal characteristics are summarized.Secondly,the dynamic response of the system under constant load is solved by numerical method,and the dynamic meshing force of meshing pairs is analyzed in time domain and frequency domain.Thirdly,the effects of operating parameters including input speed and input torque on the dynamic response of the system are analyzed,and the resonance characteristics and applicable working conditions are obtained.Finally,the dynamic responses of NGWN(II)and common NGW under the same working conditions are compared.It is found that the vibration of NGWN(II)is much severer than that of NGW when the working condition is consistent.(2)In view of the low efficiency of NGWN(II)planetary gear transmission,the reason for low efficiency is studied by element analysis method.The design method of low-loss gears is proposed to improve system efficiency.The methods to achieve low-loss gears are optimizing modification coefficients and addendum coefficients simultaneously in order to equalize recess-contact ratio and approach-contact ratio as well as obtain small contact ratio,resulting in remarkably improved efficiency of the meshing pair.It is explained that the design of low-loss gears should be adopted in the two pairs of internal meshing pairs in NGWN(II)planetary gear transmission,and the relation between the contact ratio and system efficiency is obtained.(3)It is studied that the dynamic characteristics of NGWN(II)planetary gear transmission using design of low-loss gears to improve efficiency with reduced contact ratio.Firstly,the influences of design parameters in low-loss gears on dynamic response are analyzed.After that,the relation between contact ratio of design of low-loss gears and dynamic performance of NGWN(II)is obtained.On this basis,the design method of NGWN(II)planetary gear transmission considering efficiency and dynamics is put forward.Finally,the range of contact ratio for design of low-loss gears in NGWN(II)planetary gear transmission is given.