Research On The Effect And Mechanism Of Magnetic Field On Friction Noise Of Automobile Disc Brake

The friction noise of the brake exists in all kinds of vehicles.It seriously affects the performance of NVH and the comfort of the vehicle.It has brought noise pollution to the city.It has become an urgent problem to be solved in the whole automobile industry.The tribological study shows that the microscopic characteristics of the friction pair are one of the main causes of the friction noise.The magnetic field can change the microscopic characteristics of the friction pair and reduce the friction noise significantly.However,there are few studies on the effect of magnetic field on the friction noise of the brake,and the study of the effect of magnetic field on the friction noise of disc brake is lacking.Therefore,the study of the influence law and mechanism of magnetic field on the friction noise of automobile disc brake is of great theoretical and practical value for improving the performance of NVH and reducing the pollution of friction noise.At the same time,it can also provide reference for the treatment of friction noise in other fields.In this paper,taking the automobile disc brake as the research object and taking the active suppression of the friction noise of the brake as the research target,the influence law and mechanism of the magnetic field on the friction noise of the brake are studied through experimental exploration and theoretical analysis.Firstly,the magnetic field environment of disc brake is set up,the disc brake acoustic vibration test-bed is remade,and the measurement system of the brake friction noise is designed,which provides the necessary test means for the study of the friction noise of the brake.Secondly,the parameter set of brake friction noise is put forward,and a large number of brake acoustic vibration tests are carried out.The influence rules of brake pressure and initial speed on braking friction noise are mastered,and the mechanism of braking friction noise is studied.The results show that the incidence of braking friction noise and the sound pressure level are higher under low braking speed and high braking pressure.The fluctuation of friction force is the direct cause of brake noise,and the violent wear of the friction disc is the fundamental cause of the braking friction noise.Thirdly,the influence of magnetic induction intensity and magnetic field frequency on noise is studied by conducting the brake friction acoustic vibration test under magnetic field.The results show that the magnetic field has the effect of reducing the noise,the greater the magnetic induction intensity is,the more obvious the effect of the suppression of the friction noise;the low frequency magnetic field reduces the braking noise and the high frequency magnetic field enhances the braking noise.Finally,with the help of OM,SEM and EDS micro analysis experiments,the inhibition mechanism of magnetic field on brake friction noise is studied based on the magnetic field tribology mechanism.The results show that the effect of reducing friction and stabilizing the friction of magnetic field is the main reason for reducing friction noise.Magnetic field attraction and refinement can also reduce friction noise;magnetic field adsorbs oxygen atoms to form an oxide film with lubrication,which increases the stability of the friction system and reduces the friction noise in a certain range.Through the above research,this paper has mastered the effect of magnetic field on the friction noise of automobile disc brake and its inhibition mechanism,which provides a theoretical support for the development of noise reduction strategy based on magnetic field.