Research On Generation Mechanism And Key Technology Of Wet Brake Noise

Wet Multi-plate Disc Brake(WMDB) is widely used in the construction machinerybraking system, because of its small abrasion, long service life, strong anti-pollutionability, easy to adjust the brake torque, good heat dissipation and low cost ofrepair.Brake vibration and noise was generated during braking process will seriouslyaffect the performance of automobile, such as deteriorating the automobile brakingstability, reducing the life of some parts and affecting the passengers’ comfort. Theresearch subject is based on the scientific and technological key project of ChongqingDajiang Xinda Vehicle Corporation,“Research on the key technologies of the wet axle”.In this paper, the WMDB was studied according to the theory of the complex eigenvalue,the numerical analysis and the finite element analysis were used to analyze the brakingsystem, the real part of the complex eigenvalue was used a basis to judge whether thebraking system in stable and study the influencing rule of some vital parameters.The main research works as follows：(1) The wet vibration noise mathematical model of the wet brake system wasestablished according to the basic structure, the working principle of the WMDB andthe characteristics of the braking process in order to study the dynamic characteristics ofthe braking process nonlinear contact of the WMDB. Based on the complex eigenvaluetheory, the stability of the wet brake system was studied by using the numerical analysismethod. The state equation was built according to the mathematical model to obtain thecharacteristic value of matrix. The theory basis for study the influence of the brakingsystem parameters on the system stability and optimizing design was provided bymaking a quantitative analysis about the stability of the braking system.(2) The finite element model (FEM) of the WMDB system was established, andthe impact of oil medium on the braking systems stability was considered for simulatingthe actual situation. The modal characteristics of the braking system in the wet oil and inthe air two different environments are compared by modal analysis to get a result thatthe modal frequency of the brake in the oil is lower than in the air, which lay afoundation for getting truer simulation results in the future.(3) The wet modal analysis on the finite element model of the WMDB was used toobtain the complex modal of the wet brake system. The real part of the complexeigenvalue was used to judge whether the braking system was in unstable or not, and the imaginary part of the complex eigenvalue was used to judge the modal frequency ofthe brake system. Then the impact of friction coefficients on the complex characteristicroots and the influence rule of other important parameters on the system stability werediscussed.(4) Based on above researches, the vibration and noise control technology of thewet brake system was proposed. The optimal control parameters were set according tothe influence rule of the braking system key parameters on the brake vibration and noise,which shows that the optimal results reduces4orders unstable modal obviously. Finallythe specific measures to prevent vibration and noise were proposed.