中文摘要：

磁悬浮轴承系统通常采用滚动轴承作为保护轴承。基于传热学、滚动轴承摩擦学以及转子动力学等理论,建立一种用两个滚动轴承组成的双层保护轴承（Double-decker auxiliary bearing,DDAB）的热学模型,通过建立热传递方程,计算轴承的摩擦热和温度分布,研究DDAB的热学特性。研究内容如下：建立双层滚动轴承（Double-decker rolling bearing,DDRB）的热传递模型,推导热传递阻抗和热传递方程,计算DDRB在普通运转条件下达到热平衡时的温度分布;研究不同结构、载荷、转速、润滑剂粘度、材料属性等参数对轴承温升的影响,并对比其与普通轴承在相同工况下的热学特性;建立试验台,实际测量轴承的温升,研究不同结构形式和润滑参数条件对于轴承热学特性的影响,探讨可以降低发热的主要措施。研究结果表明：DDRB的径向载荷和内圈转速直接影响轴承摩擦力矩的大小进而影响轴承的发热,在相同工况下DDRB比普通滚动轴承的内圈温升要小5%～20%,外圈温升要小10%～30%;结构、润滑剂粘度、材料的热学性能对轴承内外圈温度分布影响较大,润滑剂的填装量在轴承空间的1/3,采用Z形结构、铝制中圈、陶瓷滚动体等可以使轴承在高速运转下获得较好的热学特性和较低的温升。

英文摘要：

Rolling-element bearings are commonly used to protect the magnetic bearing system as auxiliary bearings.On the basis of the thermal transfer theory,tribology of rolling-element bearing and rotor dynamics,a new thermal structure of double-decker auxiliary bearing（DDAB） is established,and then the thermal characteristics are analyzed through building the heat transfer equations and computing the friction heat and temperature.Details of studies are as follows： after the establishment of the heat transfer model of double-decker rolling bearing（DDRB） and the derivation of heat transfer resistance and equations,the temperature rising of DDRB is analyzed under normal conditions when gets heat balance.The effects on temperature rise of DDRB concerning various structures,loads,speeds,viscosities of lubricant as well as material properties are discussed.And the calculation results are compared with those of the traditional bearings under the same operation conditions.Test rig is built to measure the temperature rises for different structures and lubricant conditions,and then the main measures to reduce heat generation are illustrated.The following results can be obtained： The radial load and the rotational speed of inner race directly influence the bearing friction torque which ulteriorly influence the heat generation,and the temperature rising of the inner race of DDRB is 5%-20% smaller than that of traditional bearings and 10%-30% smaller of the outer race;Viscosities of lubricant and thermal properties of material have great influence on the temperature distribution of inner and outer race.1/3 lubrication amount of the space of the bearing,Z-structure,aluminum middle ring,ceramics balls can make the bearing obtain better thermal characteristics and a lower temperature rise under high speed.