汽车制动抖动机理及改善研究

为分析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了制动抖动时频特征，基于快速傅里叶变换对DTV数据进行了频次分析，利用多体动力学方法计算了悬架系统模态。研究表明：制动抖动整车道路试验的振动加速度频谱具有阶次特征；DTV数据频次分析的频域成分以一次和二次DTV为主，这与制动抖动能量集中在一阶和二阶频带的特征吻合，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，模态特征值越高，制动抖动程度越轻，合理匹配悬架衬套刚度能有效改善制动抖动。

Study on Mechanism and Improvement of Vehicle’s Brake Juddering

In order to study the influence of Disc Thickness Variation (DTV) and bushing stiffness of suspension on brake judder, in this paper, the time-frequency characteristics of brake judder were studied through vehicle road test. The frequency analysis of DTV data was carried out based on FFT, while the suspension modes were calculated using multi-body dynamics program. The results show that the spectrum of vibration acceleration under vehicle road test has 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 of brake judder, it is helpful to improve brake judder by decreased amplitude of harmonic components. The longitudinal mode is the reason of brake vibration is strongly excited, the higher bushing stiffness of low control arm, the bigger suspension modal eigenvalue and the lighter brake judder. Therefore, brake judder can be reduced if the stiffness of bushings are reasonably calibrated.