JPH06124833A - Magnetizing device for magnet - Google Patents

Abstract

PURPOSE:To prevent occurrence of loss caused by uneven magnetic flux density by evenly magnetizing a disk, used for large magnetic bearings, etc., in annular. CONSTITUTION:A magnetizing device for a magnet consisting of a mechanism that rotates a disk body or annular body, which is a magnetized object 1, around its center axis 2, and an electromagnet which generates a magnetic field by cutting a portion of rotational place of the disk body or annular body from both sides of the rotational plane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a method for magnetizing a large magnet, particularly a magnet used in a magnetic bearing in combination with an oxide superconducting material.

[0002]

2. Description of the Related Art Recently, magnetic bearings utilizing magnetic flux pinning of oxide bulk superconducting materials have been studied. This magnetic bearing is characterized in that one of them is levitated and rotated by a magnetic interaction generated between the magnet and the oxide superconducting bulk. Since this method does not require mechanical contact, extremely low loss rotation can be obtained. Utilizing this fact, a superconducting flywheel that rotates a large disk and stores electric energy as kinetic energy of rotation has been studied.

In order for an object magnetically levitated by utilizing the magnetic flux pinning phenomenon to rotate smoothly, at least one of the magnet and the superconductor must create a uniform magnetic field in the rotating direction. With the current technology, the size of oxide superconductors that can withstand use is limited, and the size of magnets that can be magnetized is also limited. In order to rotate a large annular object with a magnetic bearing, small members are used side by side. In other words, by arranging multiple magnets so that they are spread concentrically, a uniform magnetic field is created in the direction of rotation, and oxide superconductors are arranged along this concentric orbit. The method of letting is taken. However, there is a problem that rotation loss occurs due to non-uniformity of the surface magnetic flux density at the magnet body or the joint portion of the magnet due to the shape and the magnetizing method.

[0004]

SUMMARY OF THE INVENTION The present invention provides a magnetizing device for a large magnet for a magnetic bearing having a concentric circular surface magnetic field distribution in the direction of rotation, which is improved from the above problems of the prior art. The purpose is to

[0005]

Means for Solving the Problems The present invention is to solve the above problems, and is a mechanism for rotating a disk-shaped body or an annular body, which is a magnetized body, around its central axis, and the disk-shaped body. Alternatively, the magnetizing device is characterized in that the magnetizing device comprises an electromagnet for generating a magnetic field by cutting a part of the rotating surface of the annular body from both sides of the rotating surface. It is also characterized in that a translational movement mechanism for the central axis of the disk-shaped body or the annular body is provided.

[0006]

In the present invention, as shown in the principle of FIG. 1, the magnetic poles 3A and 3B of the electromagnet are arranged with a part of the rotating surface of the magnetized object 1 to be magnetized which is to be magnetized sandwiching the rotating surface. A magnetic field 5 is generated by means of which a means for gradually applying a magnetic field while rotating it about the central axis 2 of the axisymmetric magnetized body to be magnetized and continuously passing through the magnetic poles is provided. . Further, by performing parallel movement 4 of the rotation axis of the magnetized body to be magnetized to the above-mentioned device as shown in FIG. 1, it is possible to magnetize the magnet having concentric surface magnetic field distributions with different radii. Is. In this case, the purpose can be achieved by moving the magnet, but it is easier to move the rotating shaft of the magnetized body.

By the means described above, it is possible to continuously and concentrically magnetize a large magnet which could not be magnetized at once. It is desirable to gradually apply the magnetic field of the electromagnet in order to reduce the rotational resistance of the magnetized body during magnetization. By reversing the polarity of the electromagnet, concentric magnetization with different radii is possible.

FIG. 2 shows the magnetic poles of a magnet magnetized by the device of the present invention. FIG. 3 is a schematic diagram when a similar magnetic pole is provided by a conventional method. That is,
In the conventional method, a seam of the magnet is generated in the circumferential direction, and for example, when the magnet tries to rotate on the superconductor, a rotation loss occurs due to uneven surface magnetic flux density at the seam. On the other hand, since the magnet magnetized by the magnetizing device of the present invention is seamless, the unevenness of the surface magnetic flux density with respect to the rotation direction can be reduced, and the rotation loss can be reduced accordingly.

[0009]

EXAMPLE As shown in FIG. 4, a magnetizing device having a Weiss type electromagnet 12 and a mechanism for supporting and rotating a magnetized body 1 having a concentric circle outside the magnetic pole was produced. The central axis 2 of the magnetized body of this device is connected to a synchronous motor by a drive belt and can rotate. Further, translational movement 11 is possible in the vertical direction. That is, 6 in FIG.
Is a pole piece, 7 is a yoke, and 8 is a coil, which constitutes an electromagnet 12. Reference numeral 9 is a support member that supports the central axis 2 of the magnetized body 1, and is vertically movable by a mechanism (not shown). Further, a pulley 10 is attached to the central shaft 2 and a drive belt (not shown) is hung on and rotated.

Application Example 1 Diameter 30 cm and thickness 1 rolled by using the above apparatus
An unmagnetized Pr-based rare earth magnet having a size of 10 cm was installed in the apparatus shown in FIG. 4 and rotated at 100 rpm. A portion having a radius of 12.5 cm of the magnet passed through the center of the magnetic pole. After this,
The electromagnet was started, and 0.1 T / min. At the speed of 1.5
It was excited to T, the magnetic field was kept at 1.5 T for 1 minute, and then demagnetized. The magnet magnetized in this manner was removed from the apparatus, and the surface magnetic field distribution was measured. As a result, it was magnetized in an annular shape with a radius of 12.5 cm. Radius 12.5
The average value of the magnetic field in the direction perpendicular to the disk on the magnet surface of 0.3 cm is 0.3.
The non-uniformity of the magnetic field at T was within ± 0.008T.

Application Example 2 After the magnetization described in Application Example 1, the magnet is moved in parallel so that a portion having a radius of 7.5 cm of the magnet passes through the center of the magnetic pole,
It was rotated at 100 rpm and magnetized under the same conditions as in Application Example 1. However, the current applied to the electromagnet was excited with the polarity reversed from that in the first application example. As a result, the magnet was magnetized so as to have surface magnetic flux densities having different polarities in an annular shape having a radius of 12.5 cm and a radius of 7.5 cm. The average values of the magnetic field in the disk vertical direction on the magnet surface with a radius of 12.5 cm and 7.5 cm are 0.3 T and -0.3 T, respectively.
Therefore, the non-uniformity of the magnetic field was within ± 0.008T.

[0012]

As described above, the magnetizing device of the present invention has made it possible to magnetize a magnet having a concentric circular surface magnetic field distribution in the circumferential direction. This magnet is useful as a magnet for a magnetic bearing with less rotation loss, and this magnetizing device is particularly useful as a magnetizing device for a large magnet for a magnetic bearing used in an energy storage flywheel.

[Brief description of drawings]

FIG. 1 is a diagram showing the principle of a magnetizing device of the present invention.

FIG. 2 is a diagram showing an example of a surface magnetic flux density distribution of a magnet magnetized by the magnetizing device of the present invention.

FIG. 3 is a diagram showing a structure of a magnet when a magnet similar to that shown in FIG. 2 is to be manufactured by a conventional method.

FIG. 4 is a diagram showing an embodiment of a magnetizing device of the present invention.

[Explanation of symbols]

 1 magnetized body 2 central axis 3, 3A, 3B magnetic pole

Claims (2)

[Claims] 1. A mechanism for rotating a disk-shaped body or a ring-shaped body, which is a magnetized body, around its central axis, and a part of the rotation surface of the disk-shaped body or the ring-shaped body is rotated from both sides of the rotation surface. A magnet magnetizing device comprising an electromagnet that cuts a surface to generate a magnetic field. 2. The magnetizing device according to claim 1, further comprising a translational movement mechanism of a central axis of the disk-shaped body or the annular body.