大型高速电机油封泄漏的改造

Oil seal reconstruction for high speed large motor

大型高速电动机转速高、主轴直径大、油封密封接触位置的线速度高,对密封材料耐磨性能要求高。电机绕组采用风叶送风冷却,风叶转动时在轴承箱内形成负压,将轴承箱内的油雾吸入转子内侧,这要求油封密封严密,对油滴和油雾要有很好的隔离作用。电机原来采用油毡密封和聚四氟乙烯浮动迷宫环密封组成的组合密封,其材料耐磨性能差,密封不严,且没有补偿性。为使油封能无泄漏长周期使用,需对密封的材料和结构进行改造:采用两道接触式密封和一道蜂窝密封,接触密封的材料选用特殊高分子复合材料,能在线速度100 m/s以下使用。接触密封做成四等分圆弧结构,圆弧之间的切口为搭接形式,每一等分可径向前后自由移动,这使密封环既密封严密,又有补偿能力;两道接触式之间连通大气;接触式密封与蜂窝密封间通入正压氮气有效地隔离负压。

Because of high speed and big main shaft, large motor＇s oil seal has high line velocity, sealing materials need to be wearable. Motor＇s winding need to be cooled by the blast of fan, when the fan is working, negative pressure is formed in the bearing housing which will inhale oil mist into the internal side of motor, so oil seal need to be seal tightly, not only for oil droplet but also for oil mist. Original, a combined sealing consist of oil felt seal and PTFE floating labyrinth seal was used, this type of material＇s wear ability is poor, and the construction is not tight and compensatory. In order to make oil seal can operate without leakage in long period, material and construction must be changed： two contacting seals and one cellular seal are adopted, special macromolecular material is used in contacting seal, which can withstand 100m/s line velocity. Each contacting seal ring is split into four equal arcs, cuts between arcs are step-cut seal, each arcs can move freely in radial direction, all these make sealing ring can seal tightly and has compensatory function. Space between two contacting seal is ventilation, and pressurizing nitrogen connected to the space between contacting seal and cellular seal, which avoid negative pressure in the bearing housing,