基于分轴升力反馈的汽车高速稳定性研究

Study on High-speed Stability of Automobile Based on Feedback of Split-shaft Lift

目前,对汽车高速行驶时的气动升力进行研究时,仅将气动力作用于风压中心点,并不能真实可靠地反映出车辆行驶时的受力及车身动态。对此,文中以某款实际在用车型为对象,对气动升力前后轴分解后的车辆行驶稳定性进行了研究。通过前后轴升力计算公式,对HD-2风洞试验数据进行处理,分别得出车辆的前后轴升力,并将其作用于搭建的整车多体动力学模型,根据侧向位移、侧向加速度和横摆角速度3个指标分析车辆的稳定性。结果表明:将气动力分解至车辆前后轴之后,在变道工况下,车辆动态表现在工况后期变差;在紧急避障工况下,车身动态表现出明显的滞后性;在车辆稳态转向工况下,车辆呈现出转向不足现象,转弯半径增大,其中侧向加速度最大值减小了0.367 5 m/s^2,横摆角速度最大值减小了1.67 (°)/s。

At present, the aerodynamic force is only placed at the center of the wind pressure in the high-speed driving aerodynamic lift study of a vehicle, so it can not reflect reliably the real force and body dynamics of the running vehicle. In this paper, the driving stability of a vehicle in use is studied after its aerodynamic lift is decomposed to front and rear axles. Through the calculation formula of front and rear axles lift, the HD-2 wind tunnel test data are processed and the front and rear axles lift of the vehicle is obtained. Then the lift is forced on the vehicle multi-body dynamics model and the stability of the vehicle is analyzed according to the three indicators of lateral displacement, lateral acceleration and yaw velocity. The results show that after the aerodynamic lift is decomposed to the front and rear axles of the vehicle, the dynamic performance of the vehicle becomes worse in the late period of lane change condition;that the body dynamics lag obviously in the obstacle avoidance conditions;that under the steady-state steering condition steering of the vehicle is insufficient and the turning radius is increased. The maximum value of the lateral acceleration is decreased by 0.367 5 m/s^2 and the maximum value of the yaw velocity is reduced by 1.67(°)/s.