【作者】 陈艳；

【导师】 王晓光；

【作者基本信息】 武汉理工大学 ， 机械工程， 2013， 硕士

【摘要】 摩擦存在于人们的生产、生活各个方面,在人类的文明建设中它有着十分重要的作用。在机械工程领域内,人类研究摩擦除了利用摩擦外,最重要的还是研究避免摩擦,减少磨损,最大限度地发挥机械效能。磁力轴承具有非接触、无磨损、无须润滑、适合高速运动等特点,具有广泛的应用前景。尽管如此,磁力轴承虽无机械摩擦,但仍存在“电磁摩擦”和“气体摩擦”。这种“摩擦”的特点体现在能量的损耗和对运动的阻力方面,因而可类似于机械的摩擦。本文首先在对磁力轴承工作原理及发展历程做简要介绍后,将从磁悬浮转子转矩平衡的角度分析研究磁悬浮支承条件下的摩擦学问题,同时也会从传统摩擦角度对磁力轴承摩擦特性做相关定义。其次,借助Ansys软件,以径向磁力轴承为对象,对旋转电磁场进行有限元分析,得到转子转速变化对磁场分布以及气隙磁通密度大小的影响规律。然后,按照等效摩擦力以及力矩的定义,建立起转子自由减速时的转矩平衡方程。接着,进行五自由度磁悬浮转子rundown实验,获取了转子自由减速的规律以及转子减速的实测值,求得了不同转速下的等效摩擦力矩变化规律。从结果来看,磁力轴承等效摩擦力矩及等效摩擦力的大小与速度有关,表现为随转速的升高而升高,其升高趋势逐渐减弱。从磁场角度解释为：当转子从静止到开始转动时,其切割磁力线的数量逐渐增加,涡流损耗以及磁滞损耗也逐渐增大,电磁阻力相应增大；由于材料有电阻,当转子转速升到某一数值时,转子表面涡流达到一恒定值,速度再增加时对其影响明显减小,导致其等效摩擦力矩及等效摩擦力有升高并且升高趋势逐渐减弱的现象。更多还原

【Abstract】 Friction, which plays a very important role in human civilization, exists in all aspects of the people’s production and life. In addition to using friction, Human studies friction to avoid friction, reduce wear and maximize mechanical performance in the field of mechanical engineering.Magnetic bearings, with non-contact, no wear, no lubrication, suitable for high-speed movement and other characteristics, has broad application prospects. In the magnetic bearings, there is still "the electromagnetic friction" and "gas friction" regardless of no mechanical friction. This "friction" is reflected in the loss of energy and the resistance to motion, which may be similar to the mechanical friction.Firstly, after a brief introduction on the working principle and the course of development of magnetic bearings, the author analyses Magnetic bearings tribological conditions from the perspective of magnetic levitation rotor torque balance, and gives some definitions on electromagnetic friction from the traditional friction angle. Secondly, the paper writer makes the finite element analysis of rotating electromagnetic field on the radial magnetic bearings by using ANSYS software, and finds that the rotor speed changes the magnetic field distribution and flux density in the air gap. Thirdly, the author establishes free deceleration equilibrium equation of the rotor torque in accordance with the definition of equivalent friction torque. Then, writer conducts a five-degree-of-freedom magnetic suspension rotor rundown experiment to get the law of the rotor free deceleration and the measured speed values. At last, we obtain different equivalent friction torque values within different segments of speed.From the results, the equivalent friction torque values of the magnetic bearing relates to its speed. As its speed gradually increasing, the equivalent friction torque values would increase, and the increasing trend is gradually weakened. From the magnetic field angle,the result is interpreted as follows: When the rotor starts to rotate from standstill, the number of lines of magnetic force which are affected by rotor’s rotational motion gradually increase, and the eddy current loss and hysteresis loss also increase, leading to a corresponding increase in the electromagnetic resistance; because of the material’s resistance, when the rotor rotational speed rises to a certain value, the rotor surface eddy current reaches a constant value. If the speed is further increased, the impact is significantly reduced, resulting in the equivalent friction torque values increased and the increasing trend gradually weakened.更多还原