| 摘要 |
<p>An assembly in which a rotating shaft (10) is supported by a magnetic bearing (11) has a back-up bearing (18), to support the shaft (10) in the event of failure of the magnetic bearing (11), the back-up bearing (18) comprising one or more constituent parts each including cylindrical rolling elements supported on a single raceway, or each part comprising a ball race with radially inner (26) and outer raceways (22). If a radially outer raceway (22) is provided it is secured to an anchorage, such as a housing (16). A layer of dry bearing material (24) is secured to rotate with the or each raceway (26) to be rotated by the shaft (10), the dry bearing material (24) having a surface (30) opposite to the shaft (10). After any failure of the magnetic bearing (11) the shaft (10) is contacted by the layer of dry bearing material (24), and the rolling elements (20) are brought up to speed at a slower rate than otherwise would be the case, because of slipping of the shaft (10) relative to the dry bearing material (24). It is arranged that, by the time the back-up bearing (18) is rotating at the same speed as the shaft (10), the back-up bearing (18) is rotating at a speed not significantly greater than the maximum design speed for the rolling elements (20). <IMAGE></p> |
