空间长寿命轴承的润滑行为及摩擦力矩稳定性研究

Bearings in momentum wheel systems are used for the attitude control of space satellites are operated with long life, high precision, high reliability and stability. Fatigue failure of the bearings in momentum wheels does not occur substantially because of the low stress in the running process of the bearings. The failure of long-life bearings is the result of the transportation and loss of the lubricants under the conditions of high-low speeds, low pressure, low gravity and temperature range of 10-80℃ in bearing chambers. In the project, the lubricating behaviors of the bearings in bias momentum wheels and reaction momentum wheels are investigated for the long life need of space satellites. The mechanism of the transportation and loss of the lubricants in the porous mediums of bearing cages and oil storage rings due to the centrifugal capillary, seepage, crawling in the bearings with micro clearances and changing operating conditions are studied. Microscale and nanoscale solid lubricating films and the micro channel techniques for directional drive of lubricants based on the wetting gradient are developed. The failure mechanism of the solid lubricating films and the synergistic effect of solid-liquid lubrication under starved state of oil lubricants are researched. The analysis method for the bearing system from macroscale of bearings to microscale contact areas and micro-nanoscale delivery channels of lubricants is built. The tribological characteristics of the contact interfaces in bearings are analyzed. The wear mechanism of the bearing cages and the dynamic change law of friction moment of bearings are revealed. The long-life evaluation method and system for space bearings is built based on the loss of lubricants, wear of bearing cages and failure of solid lubricating films. The theories and methods of the study on bearing lubricating behaviors, tribological characteristics and life evaluation are ultimately used for achieving the long life and high reliability of the space moving parts. The requirement of bearings in bias momentum wheels for running more than 15 years with high reliability, and that of bearings in reaction momentum wheels for stable operation of 8-15 years with high precision will be achieved.

空间卫星姿态调控用动量轮轴承系统需要长寿命、高精度、高可靠稳定工作。动量轮轴承工作应力很小，基本不会发生疲劳失效，长寿命条件下的失效原因主要与轴承腔低气压、低重力、10-80℃温区环境及高、低转速工况下的润滑剂输送和损耗相关。项目针对空间长寿命需求下偏置动量轮高速轴承和反作用动量轮低速过零正反转轴承的润滑行为，探索微间隙变工况下轴承保持架和储油环多孔介质在离心、毛细、渗流、爬行等多种作用下的润滑油输送与耗散机理；发展微纳固体润滑涂层和润湿梯度定向驱动润滑油微通道技术，探索固体润滑损耗机制和乏油润滑状态下的固液复合润滑协同效应；构建从宏观轴承到微观接触界面和润滑剂微纳输送通道的跨尺度系统分析方法，获取轴承内部接触界面摩擦特性，阐明轴承保持架磨损机制和轴承摩擦力矩动态变化规律，建立基于润滑油耗、保持架磨损以及固体薄膜损耗的空间轴承长寿命评价方法体系。最终通过对轴承润滑行为、摩擦特性以及寿命评价的系统研究，为空间活动部件长寿命和高可靠性的实现提供理论和方法指导，以满足姿控高转速轴承15年以上高可靠的连续运转要求，以及低速正反转过零轴承高控制精度稳定运转8-15年要求。

随着我国空间飞行器攻防技术持续深入，控制系统需要在长服役寿命周期内实现高精度和高可靠性的稳定输出。作为空间飞行器姿态调控系统的核心零部件，动量轮轴承在长寿命条件的失效原因主要与空间环境、运转工况及其润滑输送与损耗直接相关。针对空间长寿命飞行器用高速偏置动量轮和反作用动量轮中轴承组件共性润滑科学技术难题，项目开展了如下研究工作：（1）构建了动量轮轴承聚酰亚胺多孔材料保持架三维孔隙结构数字化模型，分析了聚酰亚胺多孔保持架中润滑油吸附、渗流、脱附和耗散行为，揭示了多孔材料保持架和储油器润滑油供给与耗散机理；（2）建立了润滑油润湿仿真分析模型，分析了轴承材料及表面织构对润滑油润湿状态及转变作用机理，提出了基于润湿梯度的润滑油防爬行和导流方法，为润滑油定向输送和防爬行提供了设计思路；（3）提出了引导面织构改善轴承润滑性能的方法，从理论和试验研究了表面织构在动量轮轴承引导面上的润滑特性，可以有效降低轴承运转摩擦力矩，为轴承摩擦力矩稳定提供了解决途径；（4）建立了动量轮轴承动力学计算分析模型及其与混合润滑耦合分析模型，分析了稳态工况、启停过程、变速过程和低速正反转过程中轴承动态特性和保持架稳定性，探讨了轴承润滑状态及其转变规律，探索了保持架磨损对轴承摩擦力矩的影响规律，为动量轮轴承润滑状态分析和摩擦力矩稳定提供了理论支撑；（5）建立了膜基体系承载特性分析模型，揭示了固体润滑薄膜摩擦学特性和固液复合润滑协同作用，开发了滚动轴承固体润滑薄膜参数设计与寿命预测模型与方法，为轴承长寿命润滑设计和预测提供了有力保障；（6）研制了基于压电微喷的主动供油装置原理样机，形成了动量轮轴承润滑技术验证平台。本项目研究工作为动量轮轴承润滑综合设计提供了理论基础和技术支撑，对提升我国空间飞行器稳定性、长寿命和可靠性具有科学价值和工程应用价值。