GB1573250A - Vibration damper for attenuating axial and radial vibrations - Google Patents

Description

(54) VIBRATION DAMPER FOR ATTENUATING AXIAL AND RADIAL VIBRATIONS (71) We, ULTRA CENTRIFUGE NEDERlAND N.V., a Body Corporate organised and existing under the laws of The Netherlands, of Schevenigseweg 44, The Hague, The 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 damper comprising a bearing for supporting a rotor, a damping element carrying the bearing and mounted in a damping vessel filled with damping medium and closed by a flexible membrane which connects the damping element with the damping vessel and a resilient rod connected at a first end to the damping element and at a second end to the bottom of the damping vessel.

In accordance with the invention a diaphragm is interposed in the connection at one end of the resilient rod to allow limited axial displacement of the bearing, the diaphragm bounding a closed chamber which is on the side of the diaphragm remote from the rod.

The interposed diaphragm contributes to greater axial elasticity, which is an advantage, since vibrations not only with radial deflections but also with axial deflections must be attenuated. Such a diaphragm furthermore allows a highly accurate influence to be exerted on the elasticity thereof, so that the axial resilience of the damper can be adjusted to the operational values of the rotor.

According to a practical embodiment, such a vibration damper is so constructed that the diaphragm is fixed in the centre, transversely to the plane of the diaphragm, to a rod end, while being fastened along its periphery. This membrane can be arranged both in the damping element and in the wall of the damping vessel.

According to a variant, the chamber is so designed that the volume thereof is adjustable. This allows influencing the measure of resilience of the diaphragm so as to adjust the diaphragm in such a way that certain vibrations can be neutralized. This is accomplished, for example, by filling the chamber with a compressible substance or medium. This can be constituted by a gas under pressure, a liquid, a liquid with an amount of gas above it, or a compressible substance such as rubber or foam rubber.

The pressure which prevails in the aforementioned substances or medium can be influenced by designing the damper in such a way that the chamber is bounded on the other side by a second diaphragm which can be depressed to a greater or lesser extent with the aid of a control member.

According to a special embodiment, this purpose is reached with the use of a construction in which both diaphragms are each rigidly connected, preferably in the centre, to at- least one magnet, in such a way that like magnet poles of these magnets face each other.

The application of pressure to one of the diaphragms with the use of an adjustable control member, such as a screw, causes the magnet which is fixed on this diaphragm to move with respect to the other magnet.

Under the action of the repellent forces between these magnets, the second diaphragm is likewise subjected to the influence thereof.

Two examples of embodiment of the invention will now be further explained on the basis of the following figures, where: Fig. 1 is a vertical transverse section through a vibration damper according to the invention; Fig. 2 is a variant of Fig. 1, likewise in a vertical transverse section.

In Fig. 1, the number 1 indicates a rapidly rotating unit of which only the lower end is shown. This unit is supported with the aid of a pivot 2 and a pivot ball 3 in a footstep 4. The latter is accommodated in a damping element 5, which is surrounded by a damping slot 6. This damping slot is provided inside a damping vessel 7, of which only the inside boundary 8 is shown. The space of the damping slot 6 is closed on the upper side by an elastic membrane 9. Under the action of this membrane, the damping element 5 is hinged, as it were, to the centre 10 of the membrane 9, which centre 10 is not capable of horizontal displacement.

Under the action of a set of springs 11, the damping element 5 is constantly subjected to forces which press it back to the central position. On the lower side, a diaphragm 12 is fitted which rests upon a thin elastic rod 13, which is fixed in the bottom 14 of the damping vessel. The diaphragm 12 is secured in position with a ring 15 which is so designed as to allow the formation of a narrow damping slot 16 between the underside of the ring 15 and the upper side of the bottom of the damping vessel. On the upper side of the diaphragm 12 is a chamber 17.

Fig. 2 illustrates, likewise in a vertical transverse section, a variant of the vibration damper according to Fig. 1. The damping element 18 is here constituted by a faintly conical body, which is again surrounded by a damping slot 19, filled with a damping medium. The thin elastic rod 20 is fixed in position at its upper end in the foot of the damping element 18, its lower end being secured to the upper side of a diaphragm 21. This diaphragm is provided on its underside with a magnet 22 positioned opposite another magnet 23, which is fastened on a second diaphragm 24. The magnets 22 and 23 face each other with like magnet poles.

A set screw 25 makes it possible to press the diaphragm 24 upwards to a greater or lesser extent. Since this allows the magnets 22 and 23 to approach each other, the diaphragm 21 will likewise be subjected to the influence thereof.

WHAT WE CLAIM IS: - 1. A vibration damper comprising a bearing for supporting a rotor, a damping element carrying the bearing and mounted in a damping vessel filled with damping medium and closed by a flexible membrane which connects the damping element with the damping vessel, a resilient rod connected at a first end to the damping element and at a second end to the bottom of the damping vessel, and a diaphragm interposed in the connection at one end of the resilient rod to allow limited axial displacement of the bearing, the diaphragm bounding a closed chamber which is on the side of the diaphragm remote from the rod.

2. A vibration damper as claimed in claim 1 wherein the diaphragm connects the first end of the rod to the damping element, the said chamber being formed in the damping element.

3. A vibration damper as claimed in claim 1 or 2 in which springs are disposed between the damping element and the damping vessel to provide a radial restoring force.

4. A vibration damper as claimed in claim 1 wherein the volume of the chamber is adjustable.

5. A vibration damper as claimed in claim 4 in which the chamber is bounded on the opposite side by a second diaphragm which can be depressed to a greater or lesser extent with the aid of a control member.

6. A vibration damper as claimed in claim 5 in which each of the two diaphragms carries at its centre at least one magnet, the magnets being arranged with like poles facing each other.

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

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. rapidly rotating unit of which only the lower end is shown. This unit is supported with the aid of a pivot 2 and a pivot ball 3 in a footstep 4. The latter is accommodated in a damping element 5, which is surrounded by a damping slot 6. This damping slot is provided inside a damping vessel 7, of which only the inside boundary 8 is shown. The space of the damping slot 6 is closed on the upper side by an elastic membrane 9. Under the action of this membrane, the damping element 5 is hinged, as it were, to the centre 10 of the membrane 9, which centre 10 is not capable of horizontal displacement. Under the action of a set of springs 11, the damping element 5 is constantly subjected to forces which press it back to the central position. On the lower side, a diaphragm 12 is fitted which rests upon a thin elastic rod 13, which is fixed in the bottom 14 of the damping vessel. The diaphragm 12 is secured in position with a ring 15 which is so designed as to allow the formation of a narrow damping slot 16 between the underside of the ring 15 and the upper side of the bottom of the damping vessel. On the upper side of the diaphragm 12 is a chamber 17. Fig. 2 illustrates, likewise in a vertical transverse section, a variant of the vibration damper according to Fig. 1. The damping element 18 is here constituted by a faintly conical body, which is again surrounded by a damping slot 19, filled with a damping medium. The thin elastic rod 20 is fixed in position at its upper end in the foot of the damping element 18, its lower end being secured to the upper side of a diaphragm 21. This diaphragm is provided on its underside with a magnet 22 positioned opposite another magnet 23, which is fastened on a second diaphragm 24. The magnets 22 and 23 face each other with like magnet poles. A set screw 25 makes it possible to press the diaphragm 24 upwards to a greater or lesser extent. Since this allows the magnets 22 and 23 to approach each other, the diaphragm 21 will likewise be subjected to the influence thereof. WHAT WE CLAIM IS: -

1. A vibration damper comprising a bearing for supporting a rotor, a damping element carrying the bearing and mounted in a damping vessel filled with damping medium and closed by a flexible membrane which connects the damping element with the damping vessel, a resilient rod connected at a first end to the damping element and at a second end to the bottom of the damping vessel, and a diaphragm interposed in the connection at one end of the resilient rod to allow limited axial displacement of the bearing, the diaphragm bounding a closed chamber which is on the side of the diaphragm remote from the rod.

2. A vibration damper as claimed in claim 1 wherein the diaphragm connects the first end of the rod to the damping element, the said chamber being formed in the damping element.

3. A vibration damper as claimed in claim 1 or 2 in which springs are disposed between the damping element and the damping vessel to provide a radial restoring force.

4. A vibration damper as claimed in claim 1 wherein the volume of the chamber is adjustable.

5. A vibration damper as claimed in claim 4 in which the chamber is bounded on the opposite side by a second diaphragm which can be depressed to a greater or lesser extent with the aid of a control member.

6. A vibration damper as claimed in claim 5 in which each of the two diaphragms carries at its centre at least one magnet, the magnets being arranged with like poles facing each other.