Emergency rolling bearing that is insensitive to axial load
The emergency rolling bearing for a rotary machine having magnetic bearings includes at least first and second bearing members with radial clearance of value ε r /2 that is of the order of half the mean radial air gap ε r of the magnetic bearings being arranged between each of the bearing members and the rotor, and axial clearances ε a are provided on either side of the set of bearing members between said set and first and second axial abutment elements secured to the rotor. The first bearing member is mounted directly in a first intermediate support element coaxial with a stator element. The second bearing member is mounted in a second intermediate support element likewise coaxial with the stator element. The intermediate support elements present a plane of contact in a radial plane perpendicular to the axis of the bearing and they are united by a resilient pre-stressed element acting in the axial direction and allowing the intermediate support elements and the bearing members to expand or move apart in the axial direction. Damper means acting in the radial direction are interposed between the intermediate support elements and the stator element.
1. An emergency rolling bearing that is insensitive to axial load, for a rotary machine having magnetic bearings presenting a mean air gap relative to a rotor, the emergency bearing comprising at least first and second bearing members such that radial clearance of value ε r /2 that is of the order of half the mean radial air gap ε r of the magnetic bearings is provided between each of the first and second bearing members and the rotor, and axial clearances ε a are formed on either side of the first and second bearing members between said assembly and first and second axial abutment elements secured to the rotor, wherein:
the first bearing member is mounted directly in a first intermediate support element that is coaxial with a stator element;
the second bearing member is mounted in a second intermediate support element that is likewise coaxial with said stator element;
the first and second intermediate support elements present a plane of contact in a radial plane perpendicular to the axis of the bearing and are united by a resilient pre-stressed element acting in the axial direction and allowing the first and second intermediate support elements and the first and second bearing members to expand or move apart in the axial direction; and
damper means in the radial direction are interposed between firstly the first and second intermediate support elements and secondly the stator element.
2. An emergency bearing according to claim 1 , including two annular end plates presenting a very low coefficient of friction that are fastened to the stator element and between which the intermediate support elements are inserted with clearance.
3. An emergency bearing according to claim 1 , wherein the resilient pre-stressed element comprises a helical spring.
4. An emergency bearing according to claim 1 , wherein the damper means comprise a corrugated metal ribbon interposed between the facing cylindrical faces of the intermediate support elements and the stator element centered on the axis of the bearing.
5. An emergency bearing according to claim 1 , wherein the damper means comprise a visco-elastic ring interposed between the facing cylindrical faces of the intermediate support elements and the stator element centered on the axis of the bearing.
6. An emergency bearing according to claim 1 , including a central rotor and first and second bearing members disposed on the outside around said central rotor.
7. An emergency bearing according to claim 1 , including a peripheral rotor of tubular shape and first and second bearing members disposed on the inside facing the peripheral rotor.