JPS5924524B2 - Magnetic circuit using anisotropic magnet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnet product using an anisotropic magnet, and relates to a combination shape of an anisotropic magnet molded product and a cider plate for improving its magnetic performance.

An object of the present invention is to increase the magnetic flux density obtained at the magnet surface.

Another object of the present invention is to obtain an integrated structure of a magnet and a shield plate.

In the case of a magnet having a plurality of poles on the same surface, it is known to increase the efficiency of the magnet by providing a shield plate, such as an iron plate, on the opposite surface from which the poles are provided.

Figure 1 shows an example in which four poles are provided on a plane, with magnet 1
An N pole and an S pole are provided on the surface 3 opposite to the surface in contact with the shield plate 2. FIG. 2 shows the case where there is no shield plate, and the magnetic flux Φ gathers at the N and S poles provided on the magnet 4. is the magnetic flux φ1” that passes through the magnet, and the magnetic flux Φ that passes through the magnet, passes through the atmosphere, and passes through the magnet again.
It becomes the sum of 2. The effect of the shield plate is to increase the amount of excited magnetic flux Φ2 by providing a material with high magnetic permeability near the magnet, which increases the surface magnetic flux density of the pole. In addition, powders such as anisotropic ferrite magnets, anisotropic manganese aluminum magnets, and anisotropic rare earth magnets, which have different magnetic performance depending on the direction, are dispersed in resin and function as magnets. In a molded product oriented in the direction in which the magnetic flux is oriented, the magnetic flux Φ1 passing through the interior decreases compared to an isotropic product, and instead, the magnetic flux Φ2 increases (see FIG. 3).

Therefore, the effect of the shield plate becomes even greater. Furthermore, by increasing the thickness of the magnet to a certain limit, the surface magnetic flux density obtained increases. This is already known, and various efforts have been made. Despite this, the surface magnetic flux density obtained with an anisotropic ferrite resin magnet with a BHmm of 1.0 MG0e is approximately 1000 Gauss. The present invention provides a structure that increases magnetic efficiency and obtains a high magnetic flux density that cannot be achieved with conventional methods, while providing an integral structure with a shield plate. In other words, concentration of magnetic flux can be achieved by providing a shield material on a surface perpendicular to the orientation direction and a surface parallel to the orientation direction of the anisotropic magnet molded product, and magnetically connecting both shield materials. This is the basis of the present invention.

To explain using an example, FIG. 4 is a cross-sectional view showing an example of a magnetic circuit structure implementing the present invention, in which an anisotropic magnet 5 is oriented in the S-N direction, (Rolled steel plate) It wraps around a shield piece 6 with a thickness of 16TW1.

The shield plate 7 is also made of SPCC, and is in contact with a surface perpendicular to the orientation direction of the magnets, and is also in contact with the shield piece 6.
The magnet is a nylon resin magnet containing 60% by volume of anisotropic ferrite powder, and its magnetic properties are BHwrml. It is lMGOe. The dimensions of the magnet are 8wn thick. In this magnetic circuit, the magnetic flux density at the surface of the shield piece 6 (indicated by N pole) is 1500 Gauss. The surface magnetic flux density using a magnet made of similar material and having the same thickness is about 350 Gauss in a uniformly oriented state, and the magnetic flux concentration by partially forming poles by magnetization is about 1000 Gauss. Conventionally, such a structure has been considered to have problems with the magnetic circuit. Fifth
The figure shows a cross-sectional view of the field part of a speaker as a conventional example, and shows a pole piece 9 in contact with the bottom surface of a ring-shaped isotropic ferrite magnet 8 and a disk-shaped magnetic body 10 in contact with the top surface of the magnet 8. The magnetic flux is concentrated in the gap 11 between the pole piece 9 and the magnetic body 10. In such an example, it is essential that the gap t between the magnet 8 and the axis of the pole piece 9 be maintained to some extent, and it must be at least wider than the gap 11 that concentrates the magnetic flux. This is the axis of pole piece 9 and magnet 8
This is to suppress leakage magnetic flux generated between the inner surface and the inner surface as much as possible. However, the structure of the present invention is extremely effective when applied to anisotropic magnets.

The reason for this is that since the directions in which the lines of magnetic force can easily pass are limited, there is little leakage magnetic flux generated in planes parallel to the orientation direction. Furthermore, as shown in Figure 4, since the shield piece 6 forming the N pole and the surface of the magnet 5 forming the S pole are extremely close to each other, the permeance coefficient of the space where magnetic flux is generated increases, resulting in a high magnetic flux density. This is one of the reasons for obtaining FIG. 6 is a partial sectional view showing another embodiment of the present invention, in which the magnetic body 13 inserted into a plurality of holes provided in the magnet 12 on the disc is provided in contact with the bottom surface of the magnet 12. It is in contact with the shield plate 14.

Naturally, the orientation direction of the magnet 12 is the axial direction of the disk.
When providing such multiple poles, a resin magnet with excellent workability is effective, and the more complex the shape of the magnetic body 13 forming the pole, the more effective the resin magnet becomes. FIG. 7 also shows another embodiment of the present invention, in which the shield plate 15 is partially cut and raised 16, and the resin magnet 1
7 and is integrally molded.

The cut and raised portion generates a strong holding force with the resin due to the contraction of the resin, and plays the role of joining the shield plate 15 and the magnet 17. The tip of the cut-out 16 is slightly lower than the magnet surface so as not to damage the mold during integral molding.
The decrease in the surface magnetic flux density obtained is small, and a level higher than the surface magnetic flux density obtained when using only a resin magnet is obtained. FIG. 8 is also an application example of the present invention, in which a fan-shaped anisotropic magnet 18 oriented in the direction of the arrow in the figure is attached to the shield plate 1.
9 and a shield piece 20 are assembled in advance and attached to a case. With this structure, it is possible to manufacture large items that cannot be integrally molded. FIG. 9 shows another embodiment of the present invention, in which projections 22, 23, 2 are provided on the shield plate 21.
4 are provided, separated by protrusions, and magnets 25
, 26, 27, 28 are provided, and magnets 25, 26
The N pole is in contact with the shield plate, and the magnets 27 and 28 are S
The pole is in contact with the shield plate.

In the magnetic circuit constructed in this way, the protrusion 22 becomes the N pole, and the protrusion 2
3 is non-polar, the protrusion 24 is an S pole, and alternate poles can be provided on the long side of the magnet. Figures 10 and 11 show application examples of the present invention, and show that the surface from which the magnetic flux is obtained as described above is not limited to a flat surface, but can also be a curved surface. Anisotropic magnets 31 provided between protrusions 30 provided radially on 29 are oriented in the radial direction.

Further, FIG. 11 shows an example in which poles are provided on the inner surface of a cylindrical shape, and a shield piece 3 provided on a ring-shaped shield case 32 is shown.
An anisotropic magnet 34 is attached between the cylinders 3 and 3, and the anisotropic magnet 34 is oriented in the radial direction of the cylinder. The shielding material referred to in the present invention is not limited to ordinary iron or iron-based alloys, but may also be a resin composition containing powder of a material with high magnetic permeability. The anisotropic magnet 12 without the body 13 and the shield plate 14 is loaded into a mold, and the resin composition containing the above-mentioned highly permeable powder is pressure-molded to form the magnetic body 13,
It is also possible to integrally mold a molded body to replace the shield plate 14.

As is clear from the above description, the present invention provides a member having shielding properties on a plane perpendicular to the orientation direction of an anisotropic magnetic molded product and a plane parallel to the orientation direction, and a shielding member provided on the parallel plane. is characterized in that it is used as a magnetic pole, and is not restricted in any way to the form of the above-described embodiment.

Furthermore, any type of anisotropic magnet may be used.
The advantages of the invention are as follows.

High magnetic flux density can be obtained.

It is easy to integrate the opening 1 magnet and the shield material.

one·). Features such as workability of anisotropic resin magnets can be effectively utilized.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing a conventional example of a magnet equipped with a shield plate, Fig. 2 is a sectional view of a magnet without a shield plate, Fig. 3 is a sectional view showing the characteristics of an anisotropic magnet, and Fig. 4 is a sectional view showing the characteristics of an anisotropic magnet.
The figure is a sectional view showing one embodiment of the present invention, FIG. 5 is a sectional view of a speaker field section used as an example, FIG. 8 is a cross-sectional view showing an example of application of the present invention, FIG. 9 is a sectional view showing another embodiment of the present invention, and FIG. An overhead view showing an example of application of the invention; FIG. 11 is also an overhead view showing an example of application of the invention. 5...Anisotropic magnetic molded product, 6,7...
...shielding material.

Claims (1)

[Claims] 1. For an anisotropic magnetic molded product, members with high magnetic seedling properties are provided in close contact with surfaces parallel and perpendicular to the orientation direction of the magnet molded product, respectively, and the cider material provided on the parallel surfaces is One end and the cider material provided on the perpendicular surface are magnetically connected, the other end of the cider material provided on the parallel surface is used as one of the magnetic poles, and the magnetic molded product or other cider material A magnetic circuit using an anisotropic magnet with the other magnetic pole.