Research On Electromagnetic Vibration And Noise Control Of Automobile Air-Conditioner Blower

In recent years,with the development of science and technology and the improvement of people's living standards,automobiles have become an important means of transportation,and the comfort of the automobile has been paid more and more attention.The noise of automobile airconditioning system is an important factor affecting the comfort of the automobile.In addition,the new energy vehicles such as pure electric vehicles and fuel cell electric vehicles that are currently developing rapidly so far,without the shielding effect of engine's vibration and noise,the noise of the air-conditioning system will be more prominent.The blower is the main noise source of the air-conditioning system,which not only present as the aerodynamic noise,but also the electromagnetic noise caused by the permanent magnet brushed DC motor.Therefore,the following work was carried out referring to the electromagnetic vibration and noise of automotive air-conditioning blowers:Firstly,the noise source of the automobile air-conditioning system is identified by the order analysis method and the coherent analysis method.The result shows that the permanent magnet brushed DC motor is one of the main noise sources,and the 12 th order and 60 th order noise are mainly noise.The transmission path of electromagnetic noise are analyzed by the shielding method.The result shows that the 12 th order and 60 th order electromagnetic noise radiate noise to the surrounding through the motor flange,and the 12 th order sound pressure level is much larger than the 60 th order,so the follow-up research aims to reduce the 12 th order noise.Secondly,a simplified three-dimensional finite element model is established based on the physical model of the motor,and its natural mode is calculated.The internal mode of permanent magnet brushed DC motor is measured by hammering method.The calculated results are in good agreement with the experimental results,and the accuracy of the 3D finite element model is verified.The modal analysis shows that the stator's vibration is mainly in the high frequency range above 2500 Hz,presenting as obvious elliptical mode,triangular mode and quadrilateral mode;the low frequency range below 1000 Hz is mainly composed of rotor and stator coupled vibration,and the coupling vibration of stator in the 614 Hz mode is large,one end of the stator is elliptical deformed,which provides an important basis for the subsequent study of the 12 th order(around 600Hz)electromagnetic vibration.Then,combined with Maxwell and Workbench motor magnetic-solid coupling method,the electromagnetic model of 2D permanent magnet DC motor is established with Maxwell,and the radial and tangential electromagnetic forces of the stator's inner surface are calculated.The 600 Hz harmonic component is dominant are both in the radial and tangential electromagnetic forces.The vibration response of the motor is calculated in Workbench.The experimental results and simulation results of electromagnetic vibration are compared to verify the accuracy of finite element simulation.It is found that the vibration velocity of the Z and Y points on the stator shell are the largest at 12 order(600 Hz).Finally,in view of the vibration response problem of the permanent magnet brushed DC motor's installed state in the blower,the 3D finite element model of the motor established above is combined with the vibration isolation pad,the flange and the flange cover to restore the motor's installation state in the blower and then calculate its vibration response.Combined with the vibration deformation of the motor installation state and the electromagnetic vibration and noise transmission path,three electromagnetic vibration and noise suppression schemes are proposed.And through the simulation comparison and experimental verification to obtain that smaller elasticity modulus of the vibration isolation,thicker flange and the change of mounting points' number can reduce the electromagnetic vibration of the permanent magnet brushed DC motor,thus reducing electromagnetic noise.In this paper,the characteristics of the natural mode,electromagnetic field and electromagnetic force,electromagnetic vibration and noise of permanent magnet brushed DC motor are studied by simulation and experiment.The installation state of the motor in the blower is restored and its vibration response is calculated.The effective vibration and noise suppression scheme is proposed on the transmission path of electromagnetic vibration and noise,which has important engineering significance.