Research On Reduction Of Electromagnetic Vibration Of Generator End Cover By Vibration Isolation Material

The vehicle alternator is one of the main sources of vibration noise of the whole vehicle.The electromagnetic noise in the low-speed section of the motor is particularly prominent,which has a great influence on the starting?idle speed and parking of the vehicle.The generator produced by a certain motor production company has outstanding electromagnetic noise problems.The company improved the electromagnetic noise problem by adding vibration isolation material between the stator and the end cover.It is imperative for the generator to carry out electromagnetic vibration damping research.In this paper,the RA-type alternator is taken as the research object,and the vibration generation mechanism and the inherent characteristics of the structure are analyzed.The modal test,motor electromagnetic vibration noise experiment and finite element simulation are combined to study the influence law of RA-type alternator electromagnetic vibration by changing the hardness of vibration isolation material.The modal frequency and mode shape of the RA-type alternator parts and the whole machine are obtained by the hammer stroke modal test.The test results provide a reference for the motor finite element model and lay the foundation for suppressing the electromagnetic noise of this type alternator.A three-dimensional model of RA-type alternator is established by Solidworks.The modal simulation analysis of the parts and the whole machine are carried out in Ansys.The correctness of the finite element model is verified by comparison with the modal test results.The experiment of RA-type alternator steady-state full-load electromagnetic vibration in the middle and low speed show that the frequency at the maximum amplitude of the electromagnetic vibration corresponds to 36 times the fundamental frequency of the motor;the electromagnetic force of the RA-type alternator is calculated in Ansoft Maxwell.The electromagnetic force of the motor at 3600 rpm is loaded into the finite element model of the RA-type alternator for electromagnetic vibration simulation calculation,and the simulation results are compared with the experimental results of the electromagnetic vibration of the motor.Verify that simulation model of the electromagnetic vibration of the RA-type alternator is correct.The electromagnetic vibration response results show that the electromagnetic excitation force frequency is close to the modal natural frequency of the rear end cover and the front end cover at 1500 Hz and 2100 Hz,respectively,causing structural resonance.The resonance peak of the electromagnetic vibration of the motor is suppressed by added the vibration isolation material between the end covers and stator.Based on the Mooney-Rivlin super-elastic law to describe the nonlinear elasticity of the vibration isolation material,the influence of the vibration isolation material hardness at different positions of the RA-type alternator on the electromagnetic vibration of the end cover is studied.The research results show that the vibration of the vibration-proof material between the front cover and the stator is the minimum amplitude of the electromagnetic vibration of the end cover when the Shore A hardness is 30 degrees,and the hardness of the vibration isolation pad here is increased or decreased by 10 degrees,which will cause the electromagnetic vibration amplitude of the end cover increased by more than 20%.The amplitude of the electromagnetic vibration of the end cap reduced as the hardness of the vibration isolating material between the rear end cover and stator decreases.When the hardness of the vibration isolation pad here is Shore A(30-50)degrees,the end cover of electromagnetic vibration amplitude is reduced within 5%.Considering the comprehensive vibration reduction and mechanical strength,the hardness of the vibration isolation pad is selected to be Shore A hardness of 50 degrees.In this paper,the vibration of the RA-type alternator transmitted to the end cover is studied by changing the hardness of the vibration isolating material at different positions between the end cover and stator,and the influence of vibration isolating material hardness on the vibration of the end cover is obtained.It has guiding significance for the technological measures in the project.