Rotor recentering after decoupling

1. A recentering device for a rotor shaft for recentering a rotor shaft relative to an axis X of a stator structure in an event of a decoupling caused by excessive imbalance, said shaft, in an absence of said decoupling, lying on the axis X and being radially supported by a bearing support disposed in a bore of the axis X in said stator structure, said bearing support having an outside diameter that is smaller than a diameter of said bore, to enable said bearing support to orbit about the axis X in the event of said decoupling, said bearing support being connected to the stator structure by radially fusible elements, said device comprising:

means for recentering the bearing support after said decoupling,

wherein the recentering means of the bearing support comprises means for generating a movement in precession by said bearing support in a direction contrary to a direction of said bearing support's orbits traveled after said decoupling, and a plurality of devices for decreasing permitted clearance of said bearing support relative to the axis X, said devices for decreasing permitted clearance being arranged regularly around the axes of two parts constituted by the stator structure and the bearing support, and each part including a first ramp provided on one of said two parts and a protuberance provided on the other of said two parts, said protuberance being, in the absence of said decoupling, radially spaced apart apart from said first ramp and configured to come into contact with said first ramp during the movement in precession of said bearing support.

2. A device according to claim 1 , wherein all the protuberances are configured to be in contact with the first ramps at a same time.

3. A device according to claim 1 , wherein each first ramp has a profile of an involute to a circle, and two adjacent first ramps are connected by a radial shoulder.

4. A device according to claim 3 , wherein each first ramp has a profile of an Archimedes spiral.

5. A device according to claim 1 , wherein the protuberances are made in a form of blocks.

6. A device according to claim 1 , wherein each protuberance is formed by an end portion of a second ramp, said second ramp having a second profile similar to a first profile of an associated first ramp.

7. A device according to claim 6 , wherein each first ramp is made of elastomer and the second ramp is made of metal and can roll on the first ramp, without sliding, after said decoupling, to generate the movement in precession.

8. A device according to claim 1 , wherein each first ramp and the protuberance are made of metal.

9. A device according to claim 8 , wherein each protuberance is located, in the absence of said decoupling, in a position radially spaced apart from an associated first ramp by a distance that is greater than an expected radial displacement of the bearing support during said decoupling.

10. A device according to claim 1 , wherein the means for generating the movement in precession comprises an elastomer ring secured to the stator structure, said elastomer ring surrounding the bearing support and being in permanent contact therewith so that the bearing support can roll without sliding in the bore of said elastomer ring after said decoupling.

11. A device according to claim 10 , wherein said elastomer ring is disposed in the bore of the stator structure.

12. A device according to claim 10 , wherein said elastomer ring is rigid and is connected to the stator structure by a flexible metal support.

13. A device according to claim 1 , comprising three first ramps and three protuberances.