汽车起步颤振的时频分析

摘要

汽车以不同的挡位和节气门开度在平路和坡路上起步时，出现的颤振，并会伴隨传动系剧烈的扭转振动现象。这种失稳现象从产生到减缓的全过程中，其振动加速度信号的频率分量和振幅具有显著的时变特征。由此，在采用短时付里叶变换、Wigner-Ville分布及连续小波变换三种时频分析方法的基础上，选择合适的方法对实车坡道M2档小油门工况下车上不同位置的颤振加速度信号进行分析，得到怠速、颤振和平稳行驶三个阶段的振动时频特性，并结合FFT频域分析方法，深入研究三个阶段的频率特性，及其颤振的原因和控制传递路径的有效手段。%Vehicle’s launch shudder is an unstable phenomenon of severe torsional vibration of driveline under different gear and throttle opening while launching in different road conditions. The phenomenon undergoes three stages, i.e. vehicle’s launching, severe shudder and smooth riding. In this procedure, frequency components and amplitudes of the vibration acceleration signal have significant time-varying characteristics. In this paper, three methods of time-frequency analysis, i.e. short time Fourier transform, Wigner-Ville distribution and continuous wavelet transform, were introduced. On this basis, the appropriate time-frequency method was chosen to analyze the acceleration signal at different positions in the car under the conditions of M2 gear and small throttle opening. Then, the vibration time-frequency characteristics of the three stages were revealed. Finally, the frequency characteristics of the three stages combined with the FFT analysis, the cause of launch shudder and control of its transmission path were studied.