GB1570358A

GB1570358A - Vibration-damping support for a rotor

Info

Publication number: GB1570358A
Application number: GB1623777A
Authority: GB
Original assignee: Ultra Centrifuge Nederland NV
Current assignee: Ultra Centrifuge Nederland NV
Priority date: 1976-04-28
Filing date: 1977-04-19
Publication date: 1980-07-02
Also published as: JPS5741619B2; DE2718347A1; IN146751B; JPS52151478A; BR7701817A; NL7604505A

Description

(54) VIBRATION-DAMPING SUPPORT (71) We, ULTRA CENTRIFUGE NEDERLAND N.V., a Body Corporate organised and existing under the laws of the The Netherlands, of Scheveningseweg 44, The Hague, Netherlands, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a vibration-damping support for a rotor comprising a step bearing mounting on a damping element, the damping element being disposed in a damping vessel filled with a damping medium and connected to the bottom of the damping vessel by a resilient rod to permit radial displacement of the damping element with respect to the axis of rotation of the rotor.

In accordance with the invention, in a vibration-damping support of this kind, the damping element carries a flat metallic ring disposed perpendicular to the axis of rotation and means are provided to create a magnetic field perpendicular to the plane of the ring whereby the ring provides radial damping.

The radial damping then results in part from the eddy current in each ring during its motion across the magnetic field. Preferably the magnetic field is created across an annular gap in which the ring is disposed. As the ring moves substantially in its own plane only a small amount of play is required for the ring in the annular gap and flow of the damping medium from one side of the ring to the other is restricted by the small size of the gap.

In the preferred construction the damping element has a central cavity which is open at one end and in which is disposed a body fixed to the wall of the damping vessel, the body defining with the damping element an annular gap or damping slot. The damping medium in the central cavity is substantially separated from the damping medium around the outside of the damping element by the radical damping ring in its annular gap and thus highly efficient damping is produced both by the damping slot between the fixed body and the wall of the cavity and by the damping slot between the damping element and the wall of the damping vessel.

The former damping slot is preferably narrower than the latter.

With the damper described, it is easy to obtain adaptation to the frequency ranges in which damping is found to be required. In the first place, this can be accomplished by providing a separate damping ring for each frequency. It is also possible, however, to arrange along the periphery of one damping ring a number of slightly differently designed magnets, some magnets of which are suitable for one frequency and other magnets being adapted to the damping of subsequent frequencies.

The invention will be described in more detail with the aid of an example illustrated in the accompanying drawing, which shows a vertical section of one embodiment of a vibration-damping support in accordance with the invention.

Of the rotor, only the portion 1 is shown, the underside of which ends in a pivot 2.

This pivot is provided at its end with a pivot ball 3 which rests in the cavity of a bearing block 4. This bearing block is accommodated in a damping element 5 which has a cylindrical boundary surface on the outside.

The bearing bowl 7 in which the lubricant for lubricating the pivot bearing can circulate is bounded at its upper side by a cylindrical portion 8 which is rigidly fastened to the damping element 5. This cylindrical portion is fixed by a membrane 9 to the damper housing 10.

The membrane 9 can be designed with corrugations, as shown, but it can also be so manufactured as to be entirely flat. This membrane allows the damping element to perform oscillatory motions about the centre 11 of the membrane, in such a way that the point about which these oscillations take place retains its position with respect to the wall 12 of the damping vessel.

The damping element 5 is supported at its underside on a thin rod 13 which is fixed at both ends: at its top in the bottom 14 of the damping element 5, and at its lower end in the bottom 15 of the damping vessel. This thin rod is sufficiently resilient to allow the damping element 5 to perform lateral movements, while the distance to the bottom of the damping vessel is nevertheless kept constant.

An eddy-current disc 16 is rigidly clamped with a retaining ring 17 to the lower end 18 of the damping element 5. The underside of this damping element is provided with a hollow 20, inside which a fixed damping body 21 is arranged which is fixed to the bottom 15 of the damping vessel. A cylindrical damping slot 19 is formed between the body 21 and the wall 22 of the hollow 20.

At the lower end of the cylindrical wall 12 is an annular magnet 23, which in cross section has substantially the form of a horseshoe. Between the poles 24 and 25 thereon extends a magnetic field which passes transversely through the metallic plate 16. The slots 26 and 27 prevent to a very major extent the displacement of damping liquid from the damping slot 19 to the damping slot 28 and conversely.

In a special embodiment, of which no further details are shown, the body 21 can be adjusted axially. i.e. vertically in the case shown in the figure. This can be accomplished, for example, by replacing the central thin rod 13 by a number of separate thin rods which are fastened to the underside of the retaining ring 17 and fixed at their other end in the bottom 15 of the damping vessel.

According to another embodiment. the body 21 can be displaced upwards or downwards by mounting the central rod 13 rotatably about its longitudinal axis and by providing it with a screw thread inside the body 21, the latter being so mounted that it can move axially but cannot rotate. All these methods make it fundamentally possible to influence and regulate the damping ring externally.

WHAT WE CLAIM IS: 1. A vibration-damping support for a rotor comprising a step bearing mounted on a damping element, the damping element being disposed in a damping vessel filled with a damping medium and connected to the bottom of the damping vessel by a resilient rod to permit radical displacement of the damping element with respect to the axis of rotation of the rotor, wherein the damping element carries a flat metallic ring disposed perpendicular to the axis of rotation and means are provided to create a magnetic field perpendicular to the plane of the ring whereby the ring provides radial damping.

2. A vibration-damping support as claimed in claim 1 wherein the magnetic field is created across an annular gap in which the ring is disposed.

3. A vibration-damping support as claimed in claim 1 or 2 in which the damping element is supported by a flexible membrane whose periphery is fixed and whose centre is attached to the upper end of the damping element.

4. A vibration-damping support as claimed in any of claims 1 to 3 in which the damping element has a central cavity in which is disposed a body fixed to the wall of the damping vessel, the body being separated from the damping element by an annular gap or damping slot.

5. A vibration-damping support as claimed in claim 4 in which the damping slot between the said body and the damping element is narrower than the damping slot between the damping element and the peripheral wall of the vessel.

6. A vibration-damping support as claimed in any of the preceding claims in which the magnetic field strength varies around the ring to provide damping at different frequencies.

7. A vibration-damping support as claimed in any of claims 1 to 5 having several rings disposed in magnetic fields of different strengths to provide damping at different frequencies.

8. A vibration-damping support for a rotor substantially as described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. cylindrical boundary surface on the outside. The bearing bowl 7 in which the lubricant for lubricating the pivot bearing can circulate is bounded at its upper side by a cylindrical portion 8 which is rigidly fastened to the damping element 5. This cylindrical portion is fixed by a membrane 9 to the damper housing 10. The membrane 9 can be designed with corrugations, as shown, but it can also be so manufactured as to be entirely flat. This membrane allows the damping element to perform oscillatory motions about the centre 11 of the membrane, in such a way that the point about which these oscillations take place retains its position with respect to the wall 12 of the damping vessel. The damping element 5 is supported at its underside on a thin rod 13 which is fixed at both ends: at its top in the bottom 14 of the damping element 5, and at its lower end in the bottom 15 of the damping vessel. This thin rod is sufficiently resilient to allow the damping element 5 to perform lateral movements, while the distance to the bottom of the damping vessel is nevertheless kept constant. An eddy-current disc 16 is rigidly clamped with a retaining ring 17 to the lower end 18 of the damping element 5. The underside of this damping element is provided with a hollow 20, inside which a fixed damping body 21 is arranged which is fixed to the bottom 15 of the damping vessel. A cylindrical damping slot 19 is formed between the body 21 and the wall 22 of the hollow 20. At the lower end of the cylindrical wall 12 is an annular magnet 23, which in cross section has substantially the form of a horseshoe. Between the poles 24 and 25 thereon extends a magnetic field which passes transversely through the metallic plate 16. The slots 26 and 27 prevent to a very major extent the displacement of damping liquid from the damping slot 19 to the damping slot 28 and conversely. In a special embodiment, of which no further details are shown, the body 21 can be adjusted axially. i.e. vertically in the case shown in the figure. This can be accomplished, for example, by replacing the central thin rod 13 by a number of separate thin rods which are fastened to the underside of the retaining ring 17 and fixed at their other end in the bottom 15 of the damping vessel. According to another embodiment. the body 21 can be displaced upwards or downwards by mounting the central rod 13 rotatably about its longitudinal axis and by providing it with a screw thread inside the body 21, the latter being so mounted that it can move axially but cannot rotate. All these methods make it fundamentally possible to influence and regulate the damping ring externally. WHAT WE CLAIM IS:

1. A vibration-damping support for a rotor comprising a step bearing mounted on a damping element, the damping element being disposed in a damping vessel filled with a damping medium and connected to the bottom of the damping vessel by a resilient rod to permit radical displacement of the damping element with respect to the axis of rotation of the rotor, wherein the damping element carries a flat metallic ring disposed perpendicular to the axis of rotation and means are provided to create a magnetic field perpendicular to the plane of the ring whereby the ring provides radial damping.