Abstract: With the continuous increase of power and torque of the power system, the problem of second-order jitter of the cross universal-joint transmission shaft becomes more and more prominent. According to the calculation formula of the additional bending moment of the transmission shaft, the larger the angle of the universal joint, the larger the additional bending moment, the larger the vehicle jitter. In this paper, the second-order vibration of the transmission shaft under the condition of large throttle acceleration at the start of a vehicle is taken as the research object. The real test and analysis of the larger vibration location are the second middle support of the transmission shaft and the main reducer housing of the rear axle. Further analysis shows that the angle between the transmission shaft α3 and α4 are larger. According to the analysis results, two optimization schemes are proposed, such as adjusting the angle of the transmission shaft and reforming the constant velocity universal joint, and the optimization effect of the whole vehicle is obvious. The research content has strong engineering significance for optimizing the second order jitter problem of the transmission shaft.

Key words: cross universal joint; transmission shaft; second-order jitter; additional bending moment

摘要： 随着动力系统功率扭矩不断提升，十字万向节传动轴 2 阶抖动问题更加凸显，研究该 问题对提升后驱车型乘坐舒适性意义重大。根据传动轴附加弯矩计算公式得出，万向节夹角 越大附加弯矩越大，整车抖动越大。文章以某车型起步大油门加速工况的传动轴 2 阶抖动为 研究对象，实车测试分析振动较大位置为传动轴第二中间支撑和后桥主减壳体，进一步分析 得知传动轴夹角 α3 和 α4 较大。根据分析结果提出了调整传动轴夹角和等速万向节改制等两种 优化方案，并且整车验证优化效果明显。该研究内容对优化传动轴 2 阶抖动问题具有较强的 工程意义。

关键词: 十字万向节；传动轴；2 阶抖动；附加弯矩