磁悬浮转子的主被动一体式保护轴承研究

Auxiliary bearings are used to support the high speed rotor and protect the active magnetic bearing system (AMBs) from damage in case of the AMBs fails. But because of the clearance between the rotor and the auxiliary bearing, some troubles about the AMBs have been occurred since the auxiliary bearing damaged by the huge impact force produced after the rotor drop. In this project, a centripetal thrust auxiliary bearing with the function of automatically eliminate and restore the radial and axial protect clearance is proposed. And this function not only can be accomplished by the control system, but also can be automatically achieved by this auxiliary bearing if the control system is completely failed. The main work in this project includes: (1) establishing the kinematics, statics and dynamics models of the rotor and the auxiliary bearing; (2)obtaining the matching design theory between the rotor and the auxiliary bearing; (3)exploring the key factors that influences the time of eliminating clearance and discussing the influences of that time on the service life of the auxiliary bearing, then obtaining the optimum time of eliminating clearance; (4)studying on the rotor drop experiments; (5)optimizing the design of the auxiliary bearing based on the theoretical and experimental results, and proposing the design criterions of the auxiliary bearing. The researches of this project can provide comprehensive protection to the rotor and enhance the reliability of AMBs as well as guide the design of the optimum time of the auxiliary bearing eliminating clearance. This project makes the AMBs have much wider foreground in industrial fields.

磁悬浮轴承系统需要一套保护轴承在系统失效后临时支承高速旋转的转子，保护系统设备不受损坏。由于保护轴承与转子之间存在间隙，转子跌落产生的巨大冲击力致使保护轴承损坏而导致设备受损的事故时常发生。本项目提出一种能够同时消除径向和轴向保护间隙的向心推力保护轴承，并且这种消除间隙的功能可以由控制系统主动完成，也可以在控制系统完全失效时由保护轴承自行被动完成。主要研究内容包括建立转子与保护轴承系统的运动学、静力学以及动力学模型；得到转子与保护轴承的匹配设计理论；探讨影响间隙消除时间的关键因素；研究间隙消除时间对滚动轴承寿命的影响，得到最佳消除间隙时间；进行高速跌落试验研究；根据理论和试验研究结果优化保护轴承的设计，提出保护轴承的设计准则。本项目的研究能够在磁悬浮轴承失效后对转子提供全面的保护，提高磁悬浮轴承的可靠性使其在工业应用中具有广阔的前景，同时为自消除间隙保护轴承消除间隙的最佳时间提供设计依据。

针对高速磁悬浮轴承转子跌落后保护轴承无法承受剧烈的碰撞导致磁悬浮轴承系统遭受损坏这一工程实际问题，提出了“磁悬浮转子的主被动一体式保护轴承研究”课题。项目执行期间成功研发了主被动一体式保护轴承装置并且申报了国家发明专利；完成了保护轴承装置控制系统与磁悬浮轴承控制系统的集成、保护轴承的静力学和运动学以及5自由度磁悬浮转子跌落至此保护轴承的动力学模型的建立；通过模拟仿真，对转子跌落后转子的轨迹、振动位移、转子转速、振动频率、滚动轴承的碰撞力、间隙消除时间等方面进行了理论研究；搭建了磁悬浮转子全尺寸试验台，进行转子最高转速为30000转/分时的转子跌落试验验证。仿真和试验结果均显示了主被动一体式保护轴承能够在转子跌落后不到1 s内快速消除原先的保护间隙；间隙消除后，转子维持在约为30μm的幅值范围内稳定旋转，同时滚动轴承也只需承受稳定的转子重力和离心力作用；另外，通过对转子振动频率进行分析可得此保护轴承消除了转子跌落后进入全间隙涡动的可能。.通过本课题的研究证明主被动一体式保护轴承能够实现在磁悬浮转子跌落后消除间隙的功能，基本消除了转子对滚动轴承的冲击，使得滚动轴承能够在稳定的工况下高速运行，大大地提高了其可靠性和寿命，同时提高了磁悬浮轴承系统的可靠性。本课题的研究结果对磁悬浮轴承的保护轴承设计以及实际应用提供了指导意义。