【作者】 孙新岳；

【导师】 卢剑伟；

【作者基本信息】 合肥工业大学 ， 车辆工程， 2010， 硕士

【摘要】 汽车摆振是指汽车在平坦的路面上直线行驶时,转向轮以一定的幅度和频率绕主销持续振动的现象。它恶化汽车的操纵性,影响行车安全,并使得汽车的动力性、经济性下降。它不仅危害大,而且很常见,因此引起国内外的普遍关注。影响汽车摆振的因素很多,如轮胎特性、车身结构参数等等,本课题组的前期工作表明,转向系统中转向梯形的运动副间隙因素对摆振系统动力学响应有很大影响。而间隙会引起较大的碰撞力,这将使得杆件产生不容忽视的弹性变形,对摆振系统动力学产生很大影响,所以研究间隙和弹性因素共同对摆振系统的影响很有必要。本文将转向梯形简化为平行于汽车坐标平面的四连杆机构,其中左转向节臂和转向横拉杆之间存在间隙,各杆件为弹性杆件,利用matlab/simulink软件建立了仿真模型,研究了杆件的间隙和弹性因素对摆振系统动力学造成的影响。同时分析了其他因素对摆振产生的影响,并提出了相应的减振措施。具体内容如下:建立了四连杆机构的动力学模型,分析了间隙因素对四连杆机构运动带来的影响,并得到了含间隙弹性四连杆机构的激励项;建立了含间隙弹性四连杆机构的有限元模型,利用matlab/simulink软件进行建模仿真,经比较发现考虑杆件弹性因素后系统的动力学响应有所改善,但是随着间隙的增大,系统最终还是进入了混沌运动状态。将转向梯形简化为四连杆机构,应用拉格朗日方程建立了含间隙刚性摆振系统的六自由度动力学模型,并结合含间隙弹性曲柄连杆机构的动力学模型,推出了含间隙弹性摆振系统的动力学模型。基于含间隙刚性、弹性摆振系统的动力学模型,利用matlab/simulink建立了相应的汽车摆振的模型,通过仿真分析,比较了刚性、弹性系统对汽车摆振带来的影响,发现:随着间隙的变化,弹性系统相对不容易使摆振进入混沌的运动状态,并给出了考虑弹性因素时间隙的取值范围。此外,本文还对车速,转向机的阻尼等相关的参数对摆振系统的影响进行了分析,并给出了相应的取值范围。更多还原

【Abstract】 Front wheel shimmy is defined as the phenomenon when the car driving in the flat straight road, the vibration of the steering wheel vibrating continually around Kingpin in a certain extent and frequency. It is not only harmful for the maneuverability and driving safety, but also performs negative influence on power performance and fuel economy performance. Because of the negative influence and widespread in many model, it cause the common concern in and out the sea.There are many factors which make impact on the wheel shimmy, such as the tire characteristics and body structure parameters. The previous studies of our team show that the clearance in the steering trapezoid of steering system has a great influence on the response of wheel shimmy. In fact, the impact forces caused by the clearance make the elastic deformation of the bar, the influence of that can not be ignored, so it is necessary to study the combined effect of clearance and flexibility factors made on the wheel shimmy.In this dissertation, the steering trapezoid set is simplified as a horizontal four-bar linkage, in which the clearance exists between the left steering knuckle arm and steering tie rod, and the bars are all the elastic rod. Simulation model is established using matlab/simulink software. On this basis, the influence of clearance and flexibility factors together on the wheel shimmy system is analyzed, other factors’impact are also studied, and the measures are given in response. Details are as follows.The dynamic model of rigid four-bar linkage which exist clearance is established, no only the influence of the clearance factor made on the linkage movement is analyzed, but also get the incentive forces of the elastic linkage. On the basis, the dynamic model of the elastic linkage is established using the finite element method, through comparison with the rigid system, the result shows that considering the flexibility the dynamic response of linkage improve, the impact force decrease much, and the clearance causing the chaos increase. But the system eventually comes into chaos status.The steering trapezoid set is simplified as a horizontal four-bar linkage, then establishing a 6-DOF dynamic model of rigid wheel shimmy considering the clearance, combined the model of elastic four-bar linkage, the 6-DOF dynamic model of elastic wheel shimmy is derived.According to the dynamic models of the rigid and elastic wheel shimmy system, the corresponding simulation model is established, through simulation and analysis, the comparison was made. The result shows the wheel shimmy system are more stable considering the flexibility factor, flexibility factor can inhibit the harmful impact of clearance, and the rang of clearance is given. The other factors’impact on the wheel shimmy is also studied, such as speed and steering damp, the corresponding range is given.更多还原