The Glacier Metal Company Limited

Ae Plc

Aeplc

Federal-mogul Engineering Limited

Nigel H New

John Black O'Rourke

A tilting pad thrust bearing arrangement (,), comprises a circular array of pads (,, . . . ) having tilt pivots (,, . . . ) and supported spaced from a carrier surface (,) by supporting springs (,) in the form of a stack of at least two annular, axially deflectable spring members (,). Each spring member (,and,) is spaced from an adjacent surface, the carrier surface (,) and spring member (,) respectively, by an array of deflection pivots (,, . . . ) disposed one pivot each between the tilt pivots of adjacent pads and acting as a fulcrum for spring deflection. The spring deflection pivots are in line axially so that upon axial loading of the bearing pads the spring (,) closest to the pads deflects at a first rate to contact the next spring (,) and the spring combination deflects at a second rate, at least until it contacts the carrier surface (,). Any number of springs may be stacked to give appropriate overall progressive deflection characterising.

Tilting pad thrust bearing arrangement

Thrust bearing arrangement

Vertical bearing assembly lubrication

Back-up bearing arrangement for a magnetic bearing

An electromagnetic axial shaft bearing 50 (FIG. 2 ) reduces rotational stresses on a ferromagnetic rotor 14' by reducing its radius and displacing inwardly the radially outer, axially extending part 51 of the stator core 15 containing an axial groove 18 and electromagnet coil 19 so that the outer stator pole 22 overlies the stator electromagnet coil.

Electromagnetic bearing arrangement

A back-up bearing (50, FIG. 1) is provided for a magnetic journal or thrust bearing by a source of pressurized fluid 52 (such as gas), channels 51 supplying the fluid to the suspension gap 30 between moving bearing armature 25 and stationary armature pole faces 28.sub.1, 29.sub.1, and magnet control means 56 responsive to a decrease in gap width at any point below an acceptable minimum to supply the fluid by way of the channel(s) to the gap to form a hydrostatic bearing between stationary and movable armatures to aid or replace the magnetic bearing support. In a journal bearing, (FIG. 3) in which coil-containing spaces (62) exist between radially extending armature limbs the spaces may be closed by an apertured bridging piece (64) extending between pole faces and fluid supplied via that space to provide both increased hydrostatic bearing area and a way of cooling the coil by a low pressure fluid bleed at all times. The armatures faces may be provided with low friction bearing material to permit rubbing contact at very low speeds or rest.

Magnetic bearing back-up

A magnetic bearing arrangement for a rotatable shaft 11 including electromagnetic journal bearings 20, 21 and electromagnetic thrust bearings 22, 23, is provided with back-up bearings provided as hydrostatic journal bearings 50, 51 and thrust bearings 52, 53. The hydrostatic bearings are energized by controls 63 responsive to detected failure of the magnetic bearing to support the shaft in any particular direction within a permitted range of displacements and supplied with fluid at such pressure to support the shaft on a fluid film at all speeds down to rest. Preferably the fluid is a gas.

Magnetic bearings with twisted laminations

Rotor and stator components for a magnetic bearing

An assembly in which a rotating shaft is supported by a magnetic bearing has a back-up bearing to support the shaft in the event of failure of the magnetic bearing, the back-up bearing comprising one or more coaxial bearing parts each including cylindrical rolling elements supported on a single raceway, or each part comprising a ball race with radially inner and outer raceways. If a radially outer raceway is provided it is secured to an anchorage, such as a housing. A layer of dry bearing material is secured to rotate with each raceway to be rotated by the shaft, the dry bearing material having a surface opposite to the shaft. After any failure of the magnetic bearing the shaft is contacted by the layer of dry bearing material, and the rolling elements are brought up to speed at a slower rate than otherwise would be the case, because of slipping of the shaft relative to the dry bearing material. By the time the back-up bearing is rotating at the same speed as the shaft, the back-up bearing is rotating at a speed not significantly greater than the maximum design speed for the rolling elements.

Low friction backup system for magnetic bearings

An assembly in which a rotating shaft is supported by a magnetic bearing has a backup bearing to support the shaft in the event of failure of the magnetic bearing. If the bearing portion of the backup bearing comprises a ball race, the radially outer raceway thereof is secured to an anchorage, such as a housing for the assembly. A low stiffness damper member in the form of an annular shaped body of resilient material also is included in the backup bearing, between the bearing portion thereof and the anchorage. Advantageously, when the magnetic bearing has failed, and the shaft is being brought to rest by being in contact with the backup bearing, the resilient body is in shear, and the body has a lower stiffness than otherwise would be the case. Thus, any tendency for the backup bearing, and/or the anchorage, to be damaged while the shaft is being brought to rest, is reduced, because the provision of the low stiffness damper causes the shaft to have a low natural frequency of oscillation.

Vibration isolated backup bearing for magnetic bearing

An assembly in which a rotating shaft is supported by a magnetic bearing has a back-up bearing to support the shaft in the event of failure of the magnetic bearing, the back-up bearing comprising a first layer of a dry bearing material, and with a surface opposite to a wear-resistant surface portion of a second layer. One layer is provided on a stationary part of the assembly, such as a housing, and the other layer is provided on the shaft. When the coefficient of friction between the first and second layers is either relatively low, or relatively high, heat can be dissipated from the back-up bearing at a low rate; or at a high rate. Heat dissipation may be enhanced by providing fins in good thermal contact with at least one of the two layers of the back-up bearing; and each such layer, advantageously, has a high thermal conductivity.

High-friction back-up bearing for magnetic bearings

A magnetic bearing assembly includes at least one electromagnet with a coil at least partially enclosed by a ferrogmagnetic core. Because of this arrangement, heat, inevitably generated within the coil in a conventional bearing, may cause the temperatures of the coil and adjacent parts of the electromagnet to rise to unacceptable values. These temperatures are reduced by placing a heat conducting member, say of copper, contiguous with the coil, and possibly inserted into the coil. Heat is conducted at a high rate to an exposed portion of the member, and is extracted efficiently therefrom by windage, or air flow, created within the apparatus having the magnetic bearing. Advantageously, the exposed portion of the heat conducting member has an extensive surface.

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Harrow, United Kingdom

Nigel H New