汽车制动抖动机理及改善研究

Study on Mechanism and Improvement of Vehicle's Brake Juddering

为分析制动盘厚薄差(DTV)和悬架衬套刚度对制动抖动的影响,通过整车道路试验研究制动抖动时频特征,基于快速傅里叶变换对DTV数据进行频次分析,利用多体动力学方法计算悬架系统模态。研究表明:通过整车道路试验得到的汽车制动抖动的加速度频谱具有阶次特征;对DTV数据进行频次分析得到的频域成分以1次和2次DTV为主,这与制动抖动能量集中在1阶和2阶频带的特征吻合,降低频次DTV幅值对控制制动抖动的振源激励有重要作用;前悬纵向模态是制动激励被放大的原因,前下控制臂后点衬套侧向刚度越高,模态特征值越大,制动抖动程度越轻,合理匹配悬架衬套刚度能有效抑制制动抖动。

In order to understand the influence of disc thickness variation （DTV） and bushing stiffness of suspensions on brake juddering, the time-frequency characteristics of the brake juddering are studied through vehicle＇ s road test. The frequency analysis of DTV data is carried out based on FFT. And the suspension modals are calculated using multi-body dynamics program. The results show that the spectrum of vibration acceleration in vehicle road test has the order feature. The DTV data mainly consists of the first-order and second-order harmonic components, which is consistent with the phenomenon that the first two orders of tire rotational speed are the main contributions to the brake juddering. Decreasing the amplitude of the harmonic components is helpful for improving the brake juddering. The longitudinal mode of the front suspension is the reason of amplification of the braking excitation. The higher the bushing stiffness of the low control arm is, the bigger the suspension modal eigenvalue is and the lighter the brake juddering is. Therefore, brake juddering can be reduced if the stiffness of bushings is reasonably selected.