Research And Control Of Brake Noise Of Automobile Disc Brake

Noise has great harm to the human body.Noise pollution is also one of the three major pollutions that have plagued humans for a long time.People have been working to suppress and eliminate noise problems long time ago.As one of the main noise sources in urban life,the problem of car noise seriously affects people's normal life.As an important component of car noise,brake noise is more and more taken seriously by car manufacturers and consumers,therefore,it is necessary to make detailed analysis and research on the mechanism and influencing factors of the car's brake noise,so as to effectively suppress or eliminate the brake noise before the brake noise occurs.This paper takes a disc brake as the research object,mainly studies the mechanism of the high-frequency noise of braking,describes its braking torque equation and braking motion equation.By combining transient analysis method,complex modal analysis method and boundary element radiation noise method.research how the friction coefficient,brake pressure,brake block structure,brake disc elastic modulus and brake pad elastic influence the vibration noise of the brake.According to the research results,optimize the brake block structure and the brake noise of the car is well controlled.Then the vibration active control model is established,and the vibration of the brake disc was reduced by combining control of PID and active force control.The specific work content has the following four aspects:(1)The vibration characteristics finite element model of a disk brake is established.Calculate the normal vibration state of the brake block by the transient analysis method.Research the influence of different friction coefficients on the normal acceleration of the brake pad.Results show that the greater the friction coefficient is,the more violent the brake block vibration is and the the average level of acceleration is higher.(2)High frequency noise prediction of the brake based on complex modal analysis method.The complex modal analysis method is used to predict the high-frequency noise of the braking system,and the unstable frequency of the system is predicted from the real part of the complex mode.Calculate the real part value of the complex modal respectively by changing the magnitude of the friction coefficient,the elastic modulus of the brake pad and the brake disc,and so on.Results show that the friction coefficient and elastic modulus have an important influence on the brake whistle.The effect of restraining the brake whistle can be achieved by reasonably changing these parameters.(3)Analysis of brake radiation noise based on boundary element method.The boundary element radiation noise method is used to calculate the radiation noise during the operation of the brake,and compare the radiated acoustic power under different parameters.Thus the influence of various parameters on the high-frequency noise of the brake is intuitively understood,and it provides a theoretical basis for improving the brake structure.(4)Research on active control method of the brake vibration.An active vibration control model of the brake was established,and the vibration amplitude and acceleration of the brake disc were controlled by combining with PID control and active force control.The inherent disturbances of the system itself are compensated by the force of an implementing agency,the vibration of the brake disc is effectively reduced.