控制力矩陀螺轴承组件摩擦力矩特性研究

控制力矩陀螺轴承组件是空间飞行器姿态控制系统的核心部件，其轴承的性能直接影响着空间飞行器姿态控制系统的控制精度和使用寿命，甚至危及空间飞行器安全.对于控制力矩陀螺轴承组件，轴承摩擦力矩大小及其波动性是轴承的关键性能指标，针对空间飞行器控制力矩陀螺轴承组件，在滚动轴承摩擦学和动力学基础上，建立六自由度控制力矩陀螺轴承组件非线性动力学微分方程组，并采用预估 校正的GSTIFF(Gear stiff)变步长积分算法进行求解，对其在有/无重力的工作环境、公 自转工况、轴承预紧力以及保持架兜孔间隙对轴承摩擦力矩幅值及其波动性的影响进行分析.分析结果表明：预紧力对轴承组件摩擦力矩影响显著，预紧力过大或过小都不利于降低摩擦力矩及其波动性，对于本文分析的轴承组件最佳预紧力为50~55N；保持架稳定性受重力影响显著，无重力时自转工况下保持架较稳定；过小的兜孔间隙会使摩擦力矩增大，过大的兜孔间隙会使摩擦力矩波动性增大，存在最优兜孔间隙使得摩擦力矩及其波动性都较小，针对本文分析型号的轴承组件，间隙比应控制在0.6~0.8之间.

Friction Torque Characteristics of Control Moment Gyros Bearing Unit

Control moment gyros bearing unit is a core component of spacecraft attitude control system. Its performance directly affects the control accuracy and life of spacecraft attitude control system, even endangers the safety of spacecraft. The friction torque and its fluctuation are the key performance indexes of the bearing for control moment gyros bearing unit. Based on the tribology and dynamics of rolling bearing, the nonlinear dynamic differential equations of the control moment gyros bearing unit with six degrees of freedom are established. GSTIFF (gear stiff) integration algorithm with variable step is used to solve the dynamic differential equations. The influences of different working environment that with/without gravity, working conditions that revolution and rotation, the axial preload and cage pocket clearance on the amplitude and fluctuation of bearing friction torque are analyzed. The analysis results show that: the preload has a significant effect on the friction torque of flywheel bearing unit, too large or too small preload is not conducive to reducing the friction torque and its fluctuation. For the flywheel bearing unit analyzed in this paper, the optimal preload is 50~55N; the cage stability is significantly affected by gravity,and the cage is more stable under the condition without gravity; too small pocket clearance will increase the friction torque, and too large pocket clearance will increase the friction torque fluctuation. For the flywheel bearing unit analyzed in this paper, the clearance ratio should be controlled between 0.6 and 0.8.