The Analysis And Strategy Research Of Brake Wheel Judder On Automobile

Brake wheel judder on automobile belongs to lowfrequency vibration when the brakehappens. Wheel judder seriously impacts the vehicle ride performance, the driver is thedirect victim, increases the possibility of the driver fatigue and mistake,impacts the vehiclestability and handling performance; aslo,increases the vibration intensity of other parts,increases the fatigue damage of related components, reduces the automobile reliability.The project cooperates with the enterprise focusing in the serious problem of brakewheel judder on automobile. from the view of vibration, many factors of the mechanismare studied through analysis/testing and simulation research. First of all,in the aspect ofvibration sources,do series of road reappearance tests/analysis of the many factors of braketorque variation and statistical analysis of the disc DTV; secondly, according to thecomplex transfer paths, carry series of modal test analysis and frequency responsefunction test of the braking system/car body/subframe/steering system and so on;Finally,carry suspension frequency test and sensitivity analysis of suspension parameters.The main conclusions are as follows：(1) The brake vibration frequency has orderrelationship with the tire speed， the first order is the most important, and thecorresponding frequency range is10-18Hz. The amplitude of second order/third order andfourth order is small，the rest higher orders are so small that can be ignored.(2) Brake discDTV is the leading cause of brake wheel judder, the first order braking torque variationcaused by DTV is the brake judder vibration source.(3) The brake-steering systemresonance frequency (24Hz) is close to the second order vibration source(20Hz～36Hz),The natural frequency12Hz of suspension system is the resonant frequency of the brakesteering wheel judder, the damping in rotation direction of suspension system is thesensitive factor of the transfer path.(4) controlling vibration sources and minimizingvibration amplification of transfer path are two effective ways to reduce brake vibration.In the aspect of transfer paths, the key point is changing the transfer characteristic betweensuspension system and steering system, the most direct way is changing the suspensiontype, such as change double wishbone independent suspension into McPherson suspension.As to controlling vibration sources, effective measures can be concluded from some ways,such as design, manufacture, assembly protection and so on.