Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1998-05-11
2000-09-12
Ramirez, Nestor
Electrical generator or motor structure
Dynamoelectric
Rotary
310 51, F16C 3906
Patent
active
061182001
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a magnetic bearing for contactless support of a movable, preferably rotating body in relation to a fixed part. Hereinafter the movable body is called "rotor" and the fixed part "stator". Rotor and stator are provided with magnetic zones, appropriately designated rotor and stator magnet respectively, which are disposed facing each other a short distance apart in at least one bearing gap of the magnetic bearing. The stator magnet is fixed to the stator in such a way that it can vibrate freely relative to the stator in substantially one plane, which is aligned parallel to the magnet faces of rotor and stator magnet facing each other in the bearing gap.
BACKGROUND OF THE INVENTION
Magnetic bearings of this type are known. In a magnetic bearing described by McHattie, see Review of Scientific Instruments, Vol. 12, pp. 429-435, 1941, with which small rapidly rotating steel cylinders are suspended contactlessly and which is equipped with axially active electromagnetic stabilization, radial vibrations of the suspended rotor are transmitted by contactless magnetic coupling to a radially movably mounted needle and damped by partial immersion of the needle in oil. Oil damping is also specified by J. W. Beams in "Double Magnetic Suspension", Review of Scientific Instruments, Vol. 34, pp. 1071-1074, 1963.
Disadvantages of this damping system are the necessary encapsulation of the movably mounted stator part to prevent oil losses, the additional assembly volume of the device necessitated by the encapsulation, and the associated relatively high manufacturing costs. As a component of mass-produced magnetic-bearing systems intended to compete directly with cost-optimized roller-bearing systems, especially in the use of such bearings for textile spindles and centrifuges, the oil damper appears to be unfavorable because of its manufacturing cost alone. Furthermore, because of circulation of part of the oil mass, the characteristics of an oil damper correspond only within limits to the characteristics of an ideal vibration damper with damping force proportional to speed, since mass acceleration forces caused by the oil circulation also become active in addition to the pure damping force.
SUMMARY OF THE INVENTION
The object of the invention is to equip a magnetic bearing with a damping system which leads to a small assembly volume and in which the circulation and coupled movement of considerable masses during damping can be largely reduced. It is also intended that the magnetic bearing will be inexpensive to manufacture.
This object is achieved in a magnetic bearing in accordance with the present invention. More specifically, a mechanical friction device is the vibrational movement of the stator magnet, which vibrates in a plane parallel to the magnet faces of the rotor and stator magnets. The friction device is preferably provided with two contact faces disposed in interlocking contact with each other, the normals to the faces thereof being oriented perpendicular to the plane of vibration of the stator magnet. During a deflection of the stator magnet, these contact faces slide along each other and damp the free vibrational movement of the stator magnet in proportion to the magnitude to which the frictional force, which controls the sliding of the contact faces over each other, is adjusted between the contact faces.
It is advantageous to provide one of the two contact faces with a smooth surface and the other with a rough surface. The smooth surface can be formed from rigid, especially metallic material, and the rough surface preferably from fabric, felt or other compliant material made from fibers.
For the purpose of adjusting a degree of damping to be made optimal for the respective application, the frictional force between the contact faces is adjustable. For this purpose, it is possible in particular to vary the pressing force between the contact faces.
It is provided in accordance with the invention that the rough surface is connected with the stator magnet, while a me
REFERENCES:
patent: 5521448 (1996-05-01), Tecza et al.
L.E. MacHattie, "The Production of High Rotational Speed", The Review of Scientific Instruments, vol. 12, No. 9 (Sep. 1941), pp. 429-435.
J.W. Beams, "Double Magnetic Suspension", The Review of Scientific Instruments, vol. 34, No. 10 (Oct. 1963), pp. 1071-74.
Fremerey Johan K.
Polachowski Stephan
Reiff Heinrich
Forschungszentrum Julich GmbH
Mullins Burton
Ramirez Nestor
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