Research On Analysis And Control Technology Of Car Steering Wheel Oscillation Induced By Braking

In recent years, our car was being developed as a rapid pace. Especially in 2009,it had broken through ten millions and became one of the country which produced more than ten millions cars. Car had already walked into people's lives,entered innumberable families,became the tool of transport instead of walk, meanwhile people put forward higher request on the ride comfort. the vehicle vibration and noise had became one of the Influencing Factor of ride comfort and the focus of the car enterprises.The vehicle company had puted a lot of manpower and material resources to research auto vibration and noise problems. The steering wheel buffeting induced by car on brake seriously affected the driver's comfortableness, and make drivers feel more tired,so studying the steering wheel buffeting is necessary.This paper is based on manufacture-learning-research cooperation project :"the NVH characteristic of chassis parts",to study the experiment and simulation of steering wheel Oscillation.Main content of this paper is as follows:firstly, Through reading the domestic and foreign relevant paper, Reviews the domestic and foreign research progress and status of steering wheel Oscillation induced by braking.Describing the vehicle stress when braking, introducing the structure of brake. Then, using Finite element and multibody dynamics method to establish the Rigid-elastic Coupling car, Including flexible steering system and other rigid systems.The input was braking torque and braking original speed, the output was steering wheel acceleration. Comparing with car road test and the Rigid-elastic Coupling car ,including steering wheel tangential and vertical acceleration with the speed, steering wheel tangential and vertical acceleration frequency spectrum,it shows that: the result of Rigid-elastic Coupling car model is similar to the result of experiment,which verifies the Rigid-elastic Coupling car model is effective.Then, the vehicle experiment of bake Oscillation was analysed. Via analyzing the time domain characteristics of steering wheel Oscillation, the steering wheel acceleration signal were small– big- small in the whole braking process. Analysising the initial brake speed and braking clutch state on the impact of steering wheel Oscillation, the conclusion is that the braking original speed and braking clutch state have a little effect to steering wheel Oscillation. Analysising the relation of steering wheel acceleration and wheel rotating speed,there is a obvious order relation between steering wheel acceleration and wheel rotating speed ,mainly in Second-order component. Analyzing data of the bench test of Brake,it showed the relationship of brake disc thickness difference, braking torque, brake pressure.Finally,this article mentioned the method to reduce the steering wheel buffeting, namely through putting rubber bushing and torsional vibration damper in the transmission path .Do orthogonal experiment of rubber bushing ,select stiffness and damping of rubber bushing as the factor,the minimum peak value of steering wheel tangential acceleration as the test objects. The optimization test results show that program 21 has the minimal peak value of steering wheel tangential acceleration.So set the bushing parameters of program 21 as optimized bushing parameters. Using the optimized rubber bushing, under the condition of brake force 35N and brake speed 120km/h, steering wheel tangential and vertical peak acceleration decreaseed 19.92%,45.49% respectively, root mean square decreaseed 29.36%,29.71% respectively; under the condition of brake force 20N and brake speed 120km/h, steering wheel tangential and vertical peak acceleration decreaseed 18.91%,40.86% respectively, root mean square decreased 36.03%,30.08% respectively. simplifying the torsional vibration damper,defining the stiffness 22152.33 and damping 0.1 ,under the condition of brake force 35N and brake speed 120km/h, steering wheel tangential and vertical peak acceleration decreaseed 67.39%,65.79% respectively, root mean square decreaseed 73.71%,56.92% respectively; under the condition of brake force 20N and brake speed 120km/h, steering wheel tangential and vertical peak acceleration decreaseed 55.79%,60.37% respectively, root mean square decreased 64.20%,58.14% respectively.