Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1994-02-08
1998-09-01
Budd, Mark O.
Electrical generator or motor structure
Dynamoelectric
Rotary
H02K 709
Patent
active
058014691
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to superconducting bearing devices, for example, for use in hydraulic machines and machine tools which require high-speed rotation, power storage apparatus for storing excessive electric power as converted to kinetic energy of a flywheel, or gyroscopes.
BACKGROUND ART
In recent years, superconducting bearing devices capable of supporting a rotary body in a noncontact state have been developed as bearing devices permitting high-speed rotation of the rotary body and having high rigidity.
It is thought that such superconducting bearing devices comprise, for example, an annular permanent magnet disposed concentrically with a rotary body and having axially opposite ends magnetized to polarities opposite to each other, and an annular superconductor opposed to the end face of the magnet and spaced apart therefrom axially of the rotary body.
However, the superconducting bearing device has the problem of being insufficient in rigidity with respect to the direction of the rotation axis and in load capacity. Another problem encountered is that the device is unable to support the rotary body in a noncontact state with good stability because the axis of the rotary body deflects owing to insufficient rigidity.
These problems are thought attributable to the following reason. The magnetic field strength H and magnetic flux density B of the permanent magnet are in inverse proportion to the distance from the magnet and decrease with an increase in the distance. Suppose the distance between the superconductor and the permanent magnet is Z, the apparent magnetic susceptibility of the superconductor is M, the field strength of the permanent magnet is H and the flux density of the magnet is B. The force of magnetic repulsion between the superconductor and the permanent magnet is in proportion to the product of the susceptibility M and the gradient of field strength dH/dZ or to the product of the susceptibility M and the gradient of flux density dB/dZ. The rigidity is proportional to the product of the susceptibility M and d.sup.2 B/dZ.sup.2. However, the gradient of field strength dH/dZ or the gradient of flux density dB/dZ of the annular permanent magnet is not great sufficiently, hence insufficient rigidity and load capacity.
An object of the present invention is to overcome the foregoing problems and to provide a superconducting bearing device capable of supporting a rotary body in a noncontact state with good stability by preventing the deflection of the axis of the rotary body.
DISCLOSURE OF THE INVENTION
The present invention provides a superconducting bearing device which comprises an annular permanent magnet portion disposed concentrically with a rotary body, and a superconductor opposed to an end face of the permanent magnet portion and spaced apart therefrom axially of the rotary body, the permanent magnet portion comprising a disk fixedly mounted on the rotary body, and a plurality of annular permanent magnets arranged on the disk at a spacing radially of the rotary body, each of the permanent magnets having axially opposite ends magnetized to polarities opposite to each other, the permanent magnets adjacent to each other being magnetized to polarities opposite to each other at their ends positioned toward the same axial direction.
Preferably, the spacing between the annular permanent magnets is 0.2 to 10 times the width of the magnets as measured radially thereof.
The present invention further provides a superconducting bearing device which comprises an annular permanent magnet portion disposed concentrically with a rotary body, and a superconductor opposed to the outer periphery of the permanent magnet portion and spaced apart therefrom radially of the rotary body, the permanent magnet portion comprising a disk fixedly mounted on the rotary body, and a plurality of annular permanent magnets arranged on the disk at a spacing axially of the rotary body, each of the permanent magnets having radially opposite sides magnetized to polarities opposite to each other, the
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Shibayama Motoaki
Takahata Ryoichi
Takaichi Hiroshi
Budd Mark O.
Koyo Seiko Co., Ltd
Shikoku Research Institute Inc.
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