Influence Of Clearance On Bearing Load And Analysis Of Bearing Life Of CRH Traction Motor

With the increasing speed of high-speed trains,the requirements for safe operation of traction motors has become increasing higher.As the supporting part of the traction motor,the reliability of the bearing directly determines the safety of the traction motor in operation.At present,the domestic emu adopts the mode of five-level repair.In the process of the train returning to the factory for advanced repair,the bearing of the motor can only be replaced completely due to the lack of accurate estimation of the health state of traction motor bearing.The early replacement of healthy bearing is bound to reduce the use efficiency of bearing.Bearing clearance is a mechanical parameter that can be easily measured during motor maintenance,this thesis explores bearing failure mechanism from the perspective of bearing clearance and establishes an algorithl for bearing life prediction based on this,then builds a corresponding software platform to improve the timing maintenance mechanism of traction motor and realize the intelligent maintenance mode of bearing.Firstly,the factors that affecting bearing life are analyzed.Bearing clearance will affect the load distribution,and thus affect the fatigue life of the bearing.The phenomenon of rotor eccentricity will occur in the traction motor When the positive clearance occurs,which will lead to the generation of eccentric magnetic tension.The eccentricity load caused by bearing clearance is considered in the analysis of bearing fatigue life,and the components of eccentricity magnetic pull force are analyzed by means of magnetic circuit analysis and series expansion based on the derivation of air gap magnetomotive force and magnetic permeability of traction motor,then the calculation formulas of eccentricity magnetic pull force are obtained.After that,the finite element software Ansys was used to build the traction motor model of the emu,the rotor eccentricity was simulated to calculate the magnetic density distribution and eccentric force between air gaps.The simulation results agree well with the analytical results,which verifies the correctness of the analytical model.In the process of establishing the bearing life prediction algorithm,this thesis discusses the basic principles and different adaptive situations of the bearing life theories,such as L-P theory,modified L-P theory,ISO standard algorithl and I-H theory.Then,the statics module in the Workbench platform was used to analyze the load distribution in bearing operation,and the modified L-P theory which adapted to the prediction of bearing life of traction motor was selected as the calculation method.Combined with electromagnetic load and mechanical load,an algorithm was established to calculate the bearing life of traction motor by using rated parameters of motor and bearing.At the same time,considering the particularity of traction motor bearing manufacturing and running,this thesis modifies the fatigue life by using the parameters of lubrication and pollution grade,which makes the calculated life universal.Finally,this thesis has compiled a calculation software of traction motor bearing life under the MATLAB platform,and the sample motor and bearing was calculated.The fatigue life calculation software can calculate the fatigue life of the bearing in real time and draw the fatigue life curve to guide the maintenance plan of the traction motor of the CRH.