JPS5846163B2 - Continuous magnetic field variable device using permanent magnets - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a yoke made of a magnetic material having a closed magnetic circuit with a mouth-shaped interior, and a large number of cylindrical permanent magnets magnetized in the diametrical direction along each of two opposing sides of the inside of the yoke. The magnets are arranged in a row, a plate (shim) made of a magnetic material is provided inside the magnet in contact with the permanent magnets, and the permanent magnets arranged in the -row are rotated so that they face the same direction of magnetization, The idea is to continuously change the magnetic field inside the yoke.

Variable magnetic field generators are used to generate a constant magnetic field or to change the traveling direction of the electron beam, such as high-energy electron beam generators that apply a magnetic field to charged particles such as electrons.

As shown in Fig. 1, a conventional magnetic field generator uses an electromagnet in which a magnetic pole 2 is provided at opposing positions inside a yoke 1 with a closed magnetic path, and a winding 3 is provided surrounding the magnetic pole 2. .

When a current is supplied to the winding 3 from the power supply 4, a magnetic field is generated between the two magnetic poles 2.

The electric current is also controlled to change the strength of the magnetic field.

However, since this type of electromagnet passes current through the windings, Joule heat is generated in the windings, and a cooling device is required to cool the Joule heat.

In addition, a stabilized power source is required to obtain a stable magnetic field, and a variable power source is required to obtain a variable magnetic field.

The conventional method requires equipment such as a cooling device and a power source as described above, and has the disadvantage of being expensive.

In order to eliminate these drawbacks, the present invention uses a permanent magnet, which eliminates the need for energy from other sources such as a power supply, and by rotating the permanent magnet, a continuously variable magnetic field is obtained. The purpose is to obtain a variable magnetic field generating device.

As shown in FIG. 2, the present invention has a closed magnetic circuit yoke 5, which is made of a soft magnetic material with high magnetic permeability such as iron, and has a cylindrical shape such as a rare earth magnet along the inner surfaces 5A and 5B. Permanent magnet groups 6A and 6B are arranged facing each other.

These permanent magnet groups 6A. 6B is magnetized in the diametrical direction of the shaft as shown by the arrow.

In addition, in order to obtain a uniform magnetic field in the opposing air gaps 8 in the permanent magnet groups 6A and 6B, a plate (shim) 1 made of a magnetic material with high magnetic permeability such as iron or permalloy is attached to the permanent magnet group 5A.
, 6B, respectively.

Here, in order to change the magnetic field within the air gap 8, the entire permanent magnet group 6A, the entire permanent magnet group 6B, or 6A.

Both 6B and 6B are interlocked as a whole so that the magnetization directions of the individual permanent magnets are the same, and each permanent magnet rotates around its central axis.

Operation of this mechanism may be manual or automatic.

FIG. 3 shows an embodiment of the present invention, and a cylindrical rare earth permanent magnet Lanthanet (trademark of Tohoku Metals) LM22 is magnetized in the diametrical direction on the inner surface of a closed magnetic circuit yoke 5 made of a soft magnetic material.
Groups 6A and 6B were arranged in an upper row and a lower row with four pieces each.

Furthermore, a soft magnetic plate 7 was provided on the gap 8 side of the upper and lower magnets 6A and 6B.

At this time, the upper and lower magnet groups 6A and 6B are rotated in conjunction so that their magnetization directions become parallel to each other.

The relative value % of the strength of the magnetic field with respect to the distance in the Z direction from the center of the air gap of the device obtained in this way is
FIG. 4 shows the results of measurement with respect to changes in the rotation angle of the magnetization direction of B.

In the figure, a uniform magnetic field is obtained over a wide range in the gap between magnet groups 6A and 6B, and magnet group 5A.

It can be seen that a continuously variable magnetic field can be obtained by rotating 6B.

Although only the magnetic field distribution in the Z direction has been described in the figure, the magnetic field distribution is similarly continuously varied in the Z direction (perpendicular to the plane of the paper), that is, in the Z-Y plane.

As explained above, since the magnetic field generator of the present invention uses a permanent magnet, it does not require external energy such as a stabilizing power supply or a cooling device, and is smaller and lower in cost than conventional ones that use electromagnetic force. It has the advantage of being able to uniformly and continuously change the magnetic field within the air gap over a wide range at a low cost.

[Brief explanation of the drawing]

FIG. 1 is a front view showing the configuration of a device using a conventional electromagnet, FIG. 2 is a front view showing the configuration of a device according to the present invention, and FIG.
The figure is a configuration diagram showing one embodiment of the device of the present invention, and FIG.
A characteristic diagram showing the magnetic field distribution of the device shown in the figure is shown. In the figure, 5: closed magnetic path yoke, 5A, 5B: inner surface of yoke, 6A, 6B: permanent magnet group, 7: magnetic plate (shim), 8: air gap.

Claims (1)

[Claims] 1. A large number of diametrically magnetized cylindrical permanent magnet groups arranged in a row with gaps between them along the opposing inner surfaces of a magnetic yoke forming a closed magnetic path, and a magnet on the gap side in contact with the permanent magnet groups. A continuously variable magnetic field display using permanent magnets, characterized in that a plate made of a thin magnetic material is provided on the cylindrical magnet, and a group of permanent magnets is rotated around the axis of each cylindrical magnet.