JPS5919377Y2 - ring magnet - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a ring-shaped magnet that shields one of the outer diameters of the inner hole of the magnet body whose inner and outer diameter surfaces are magnetized to obtain a high magnetic flux density on the other surface.

Conventional ring-shaped magnets have been developed in which either the inner or outer diameter of the ring-shaped magnet body is magnetized, and a shield layer made of a magnetic material such as iron is provided on the non-magnetized side. has been done.

For example, if the inner diameter surface of the magnet body is magnetized, a magnetic flux of 800 Gauss will be obtained on the inner diameter surface and 100 Gauss on the outer diameter surface, and if a shield layer is formed on this outer diameter surface, the magnetic flux density on the inner diameter surface will be 850 Gauss. had improved.

However, with this configuration, the effective magnetic flux density on one side was only slightly improved, and could not be said to be fully satisfactory.

The present invention eliminates the above-mentioned drawbacks of the prior art.

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3.

First, in FIG. 1, 1 is formed into a ring shape from a mixture of ferrite powder and rubber, ferrite powder and synthetic resin, or ferrite powder, rubber, and synthetic resin;
The magnet main body 1 is magnetized on its inner and outer diameter surfaces, and a shield layer 2 made of a magnetic material such as iron is formed on the inner diameter surface of the magnet main body 1 to form a ring-shaped magnet.

Furthermore, the magnet shown in FIG. 2 has a shield layer 2 formed on the outer diameter surface of a magnet main body 1 whose inner and outer diameter surfaces are magnetized.

Assuming that the magnetic flux when both the inner and outer diameter surfaces of the magnet body 1 are magnetized with the above configuration is 800 Gauss, the effective magnetic flux density will be lower, although it varies depending on the thickness of the magnet body 1, that is, the difference in dimensions between the inner and outer diameters. It will look like a table.

As a result, when the thickness of the magnet body 1 becomes 8 mm or more, the effect of magnetizing both the inner and outer diameter surfaces is almost eliminated.

Next, the magnet body 1 is obtained by magnetically molding a mixture of ferrite powder and rubber or ferrite powder and synthetic resin in a molding machine equipped with a magnetizing yoke that provides the necessary magnetic field in a molding die, and then demagnetizing the mixture. As shown in FIG. 3, a ring-shaped magnet main body 1 is arranged between a plurality of magnetizing yokes 4 and 5 arranged at regular intervals so as to face each other with a space in which the magnet main body 1 of a magnetizer 3 is fitted. It is formed by being magnetized.

In this way, the ring-shaped Yama magnet main body 1 magnetized on both the inner and outer diameters is effectively magnetized on both the inner and outer diameters, so it becomes a ferromagnetic magnet having the same magnetic flux density on the inner and outer diameters.

When using the magnetic force on the outer diameter surface as shown in FIG. 1, the flow of magnetic flux when the shield layer 2 is formed on the inner diameter surface will be explained with reference to FIG. 4.

As shown in the figure, from the magnetic pole 6 on the inner diameter surface to the magneto main body 1
The magnetic flux that should be radiated toward the center of the magnet passes through the inside of the shield layer 2 as a magnetic flux 7 using the shield layer 2 as a magnetic path, reaches the adjacent demagnetizing poles 8 and 9, passes through the magnet body 1, and reaches the inner diameter surface. It is radiated to the outside from magnetic poles 10 and 11, which are the same magnetic pole as the magnetic pole 6.

The magnetic force on the inner diameter surface via this shield layer is combined with the magnetic force on the outer diameter surface after magnetization, resulting in a magnet having stronger magnetic force on the outer diameter surface.

As shown in the table above, the value of this magnetic flux density varies depending on the thickness of the magnet body 1 because of the distance A from the magnetic pole on the inner diameter surface to the outer diameter surface, and the attenuation of the magnetic flux density depends on the magnetic properties. This is because it is proportional to the square of the distance.

As described above, the magnetic force was limited by the magnetizing force and the magnet material, but by utilizing the material throughout the magnet thickness direction, it is now possible to provide a magnet with stronger magnetic force.

In the case of the embodiment shown in FIG. 2, until magnetization, both the inner and outer diameters are effectively magnetized in the same manner as described above, and by forming the shield layer 2 on the outer diameter surface, the magnetic flux on the outer diameter surface is transferred to the inner diameter surface. The magnetic flux is combined with the magnetic flux and radiated from the inner diameter surface, and the same effect can be obtained.

In this way, the ring-shaped magnet of the present invention has a simple structure and a high effective magnetic flux density through the same manufacturing process, so it can be made smaller and thinner, and has great practical value. .

[Brief explanation of drawings]

Fig. 1 is a front view showing one embodiment of the ring-shaped magnet of the present invention, Fig. 2 is a front view of another embodiment, Fig. 3 is an explanatory diagram showing the magnetization process of the magnet body, Fig. 4 is a partially enlarged front view illustrating the flow of magnetic flux of the same magnet. 1... Ring-shaped magnet body, 2...
...Shield layer.

Claims (1)

[Scope of utility model registration request] A ring-shaped magnet made of a mixture of ferrite powder, rubber, and/or synthetic resin, with a ring-shaped magnet body magnetized on its inner and outer diameter surfaces, and a shield layer of a magnetic material provided on one of the inner and outer diameter surfaces.