JPH0487539A - Superconducting magnetic bearing motor - Google Patents

Abstract

PURPOSE:To obtain a miniature magnetic bearing motor having high performance by employing a high temperature superconductor and a magnetic bearing constituted of a doughnut type permanent magnet having N and S poles in the axial direction and fixing a driving permanent magnet while spacing apart the superconductor. CONSTITUTION:A disc type high temperature superconductor 2 to be cooled by liquid nitrogen LN is arranged in a liquid nitrogen vessel 1 and a doughnut type levitation bearing permanent magnet 3 is disposed above the center of the superconductor 2. A rod type rotation driving permanent magnet 5 having projecting N and S poles at the opposite ends is fitted to the upper end of an annular rotor shaft body 4 having lower end fitted to the magnet 3. Rotation driving solenoids 6, 7, 8 generating rotational fields are disposed at the upper end of the rotor shaft body 4. A rotor 9 is constituted of the levitation bearing permanent magnet 3, the rotor shaft body 4 and the rotation driving permanent magnet 5. The rotor 9 is pressed against the high temperature superconductor 2 thus stably rotating the rotor shaft body 4 of the rotor 9.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application: The present invention relates to a motor having a superconducting magnetic bearing.

:Prior art= Conventionally, as a magnetic bearing, a type that is electrically controlled by a complicated fliJm feedback circuit, which is used in a vacuum turbo molecular pump, etc., has been used.

On the other hand, as a motor that utilizes the Meissner effect of high-temperature superconductors, a cantilever type motor uses a rotor in which north and south poles are arranged alternately in the circumferential direction (US Pat. No. 48928
No. 63).

: Invention or problem to be solved [However, the former is not used for very small devices due to its complicated control circuit, and the latter uses the same magnet for rotational drive as the magnet for levitation. High-speed rotation was difficult because the magnetic flux moved through the superconductor due to changes in magnetic flux density as it rotated, creating resistance.

In this respect, it is an object of the present invention to provide a small motor capable of rotating at high speed using a magnetic bearing with a simple structure that does not require a complicated control feedback circuit.

Means for Solving Two Problems] The above problems are achieved by the present invention adopting the following characteristic configuration means.

The features of the present invention include a superconductor cooled to a high temperature, a levitation bearing set on the high temperature superconductor and having N5ffl in the axial direction, a donut-shaped permanent magnet, and a toroidal permanent magnet attached to the levitation bearing. The rotor is composed of a rotor shaft body fitted at one end, a driving permanent magnet attached to the @ end of the rotor shaft body, and a rotating magnetic field is generated by disposing the rotor around the driving permanent magnet. A superconducting magnetic bearing comprising at least three drive solenoids that act as a motor.

2 Functions: The present invention takes the above-mentioned measures and installs a donut-shaped permanent magnet having an NS pole in the axial direction for levitation and a permanent magnet for driving, which constitute a magnetic bearing, respectively, on the rotor shaft body. Provided at both ends.

In the present invention, N54I! The reason why the levitation bearing has a magnetic bearing constituted by a donut-shaped permanent magnet and the drive magnet is provided as a shield from the donut-shaped permanent magnet is explained below.

When a permanent magnet is placed on top of a yttrium-based high-temperature superconductor cooled by liquid nitrogen, the permanent magnet is repelled by the high-temperature superconductor due to the Meissner effect. At this time, when a permanent magnet is pressed against a high-temperature superconductor, the magnetic flux is trapped, and the permanent magnet is stably held at a point in the air. At this time, the motion of the permanent magnet that does not change the spatial distribution of magnetic flux passing through the superconductor is not resisted, that is, N
In the case of a permanent magnet that is rotationally symmetrical with respect to the axis that connects the south pole, a donut-shaped permanent magnet with north and south poles in the axial direction, which is not subject to resistance to rotational movement around the opposite axis, is used as a bearing. When used as a magnet, as mentioned above, there is no resistance force from the superconductor against rotation in the circumferential direction, and by making it into a donut shape, the area receiving the repulsion force increases, making the rotor shaft body The fixation of the rotor shaft body is automatically done by pressing the rotor against the superconductor, and there is no need for Flk adjustment or sub-legs. In the case of a rotor with N3[r arranged in the circumferential direction so that the same magnet can be shared, the magnetic flux distribution changes with rotation, so the resistance to the movement of the magnetic flux in the superconductor is large and the rotor does not rotate smoothly. By attaching the rotational drive magnet at a distance from the superconductor, it is possible to prevent it from receiving resistance due to changes in magnetic flux distribution due to rotation. In this way, the bearing, which is a feature of the present invention, uses a donut-shaped permanent magnet with NS poles in the axial direction as a magnet, and the magnet for rotational drive is mounted away from the superconductor, thereby achieving a superconducting magnetic bearing. The motor is provided with a superconducting magnetic bearing that maximizes the features of the motor.

= Example code Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic perspective view of this embodiment.

In the figure, A is the motor of this embodiment, 1 is a cylindrical liquid nitrogen container containing liquid nitrogen LN, 2 is a disc-shaped high temperature superconductor installed in the liquid nitrogen container 1 and cooled by the liquid nitrogen LN, 3 is a donut-shaped floating bearing mounted on the center of the high temperature superconductor 2, which is a permanent magnet; 4, the lower end of which is a levitating bearing, is a rotor shaft body fitted with the permanent magnet 3; and 5, a rotor shaft body. 4
Around the upper end of the rotor shaft body 4, a rod-shaped permanent magnet for rotational drive is attached in the upper end in the diametrical direction and has S and N poles protruding from both ends. 9 is a rotor consisting of a permanent magnet 3 for a floating bearing, a rotor shaft body 4, and a permanent magnet 5 for rotational drive.

(Application example 1) Y B a 2 Cu 30. calcined in oxygen at 920° C. for 12 hours. High temperature superconductor powder diameter 6
ae, thickness 1 > 4. Near 1i, 940”C
, sintered in oxygen for 100 hours to produce bulk high temperature superconductor 2
was created. This high temperature superconductor 2 is cooled in liquid nitrogen LN to a superconducting state and has an outer diameter of 2°8mm.

When a donut-shaped rare earth permanent magnet 3 having an inner diameter of 1°2 and a N of 0.2ao was levitated, a flying height of 1.2 was obtained. As shown in FIG. 1, this donut-shaped permanent magnet 3 is fixed to one end of the rotor shaft body 4, and a driving permanent magnet 5 is attached to the other end.
The superconducting magnetic bearing was installed as the rotor 9 of motor A.

By pressing this rotor 9 against the high temperature superconductor 2, the stability of the rotor shaft body 4 of the rotor 9 was improved and the rotor was rotated. At this time, the flying height of the rotor 9 was 0.4. was configured. Solenoids 6, 7, and 8 each have a phase of 90°
The rotor 9 was driven by flowing a shifted sine wave to generate a rotating magnetic field. When the frequency of the sine wave was changed in the range of 20 to 460 kHz, the rotation speed was 500 to 11 QQ rpm.

(Application Example 2) A superconducting magnetic bearing having the same configuration as Application Example 1 was used to rotate motor A in a vacuum chamber. The degree of vacuum in the vacuum chamber was 5 mtorr, and the bulk high temperature superconductor 2 was cooled by heat transfer from liquid nitrogen LN contained in a liquid nitrogen container 1 provided below the high temperature superconductor 2. The temperature of the upper surface of the high temperature superconductor 2 is 84, and the flying height of the rotor 9 after pressing the rotor 9 against the high temperature superconductor 2 is 0.3.
It was a country. The maximum rotation speed was 2850 rpm.

2. Effects of the Invention As explained above, according to the present invention, a magnetic bearing composed of a high-temperature superconductor and a donut-shaped permanent magnet having NSi in the axial direction is used to superimpose a permanent magnet for rotational drive. By mounting C separately from the conductor, a high performance compact magnetic bearing can easily be used to construct a motor. This motor does not require any complicated control such as fine adjustment of the magnetic bearing, and it has the advantage that it can be configured to perform even better in a vacuum than in air. These small, high-speed rotation type motors have excellent effects, such as contributing to the miniaturization of devices when used in gyros, etc.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing an embodiment of the present invention. A...Superconducting magnetic bearing is motor LN...Liquid nitrogen 1...Liquid nitrogen container 2.
・・High-temperature superconductor 3 ・・Leaving bearing uses permanent magnet 4 ・Rotor shaft body 5 ・Permanent magnet for rotational drive 6.7.8 ・Solenoid for rotational drive 9 ・Rotation Child figure 1

Claims (1)

[Claims] 1. A cooled high-temperature superconductor, a donut-shaped levitation bearing permanent magnet set on the high-temperature superconductor and having an NS pole in the axial direction, and a rotating magnet whose one end is fitted to the levitation bearing permanent magnet. A rotor consisting of a child shaft body and a permanent magnet for rotational drive attached to the other end of the rotor shaft body, and at least three magnets arranged around the permanent magnet for rotational drive to generate a rotating magnetic field. A superconducting magnetic bearing motor characterized by comprising a rotary drive solenoid.