JPS638090Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field The present invention relates to a magnetic device using an anisotropic magnet, and in particular, a combination shape of an anisotropic magnet molded product and a shield plate to improve the magnetic performance. It is related to.

BACKGROUND OF THE INVENTION 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. 1st
The figure shows an example in which four poles are provided on a flat surface, with N on the surface 3 opposite to the surface where the magnet 1 and the shield plate 2 touch.
A pole and a south pole are provided. Figure 2 shows the case where there is no shield plate, and the magnetic flux Φ ₀ that gathers at the N and S poles of the magnet 4 is combined with the magnetic flux Φ ₁ that passes through the magnet, passes through the magnet, passes through the atmosphere, and returns again. It is the sum of the magnetic flux Φ ₂ passing through the magnet.
The effect of the shield plate is to increase the amount of excited magnetic flux Φ ₂ 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, whose performance as magnets differ depending on the direction, are dispersed in resin and used as magnets. In a molded product oriented in the functional direction, the magnetic flux Φ ₁ passing through the interior decreases compared to an isotropic product, and Φ ₂ increases instead (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. Nevertheless, BH _nax
The surface magnetic flux density obtained with a 1.0MGOe anisotropic ferrite resin magnet is approximately 1000 Gauss.

Generally, the attraction force of a magnet is 2 times the surface magnetic flux density.
Since it is proportional to the power of the surface magnetic flux density, efforts are being made to increase the surface magnetic flux density. A typical example is the field part of a loudspeaker. FIG. 5 shows a sectional view of the field part of the speaker, showing a pole piece 9 in contact with the bottom surface of the magnet 8 made of ring-shaped isotropic ferrite, 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 necessary that the gap l between the magnet 8 and the axis of the pole piece 9 be maintained to some extent, and it is required to be at least wider than the gap 11 that concentrates the magnetic flux. This is to suppress leakage magnetic flux generated between the axis of the pole piece 9 and the inner surface of the magnet 8 as much as possible.

Problems to be Solved by the Invention However, providing the gaps as described above takes time and effort in manufacturing, and means must be taken to maintain the overall positional relationship.

Therefore, the present invention provides a magnetic device that can be easily integrated and manufactured while solving the essential problem of increasing the surface magnetic flux density.

Means for Solving the Problems In order to solve the above problems, the magnetic device using the anisotropic resin magnet of the present invention has a magnetic device on one of the surfaces intersecting the orientation direction of the oriented anisotropic resin magnet. Highly shielded members are placed closely together,
This magnetic shielding member has a portion cut and raised, and the cut and raised portion is integrated into an anisotropic resin magnet along the orientation direction.

By using these means, the shield member and the anisotropic resin magnet can be easily integrated because in addition to the magnetic bonding force, a mechanical bonding force is applied due to the contraction force of the resin magnet against the cut and raised portion. In addition, since the cut and raised portion approaches the other plane intersecting the orientation direction, the magnetic flux is concentrated there, making it possible to improve the magnetic flux density.

That is, FIG. 4 is a model representation of the magnetic circuit of the magnetic device of the present invention, and 5 is a resin magnet, which is oriented and magnetized in the N-S direction. Reference numeral 7 denotes a magnetic shielding member, which is in close contact with one of the surfaces of the resin magnet 5 that intersects with the orientation direction. Reference numeral 6 denotes a member with high shielding properties, which corresponds to a cut-and-raised portion. From FIG. 4, it can be seen that the lines of magnetic force coming out of the resin magnet are concentrated at the cut and raised portion.

Embodiment Hereinafter, an embodiment of the present invention will be described based on the drawings.

FIG. 6 is a cross-sectional view showing one embodiment of the present invention, in which the shield plate 13 is partially cut and raised at a portion 14.
is provided and integrally molded with the resin magnet 12. 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 13 and the magnet 12. Cut and raise part 1
The tip of No. 4 is slightly lower than the magnet surface to avoid damaging the mold during integral molding, but the resulting surface magnetic flux density decreases little, and the surface magnetic flux density obtained is higher than that obtained with only a resin magnet. It will be done.

The material of the shield plate 13 is SPCC (cold rolled steel plate)
etc., and press working is suitable as a means for making the cut and raised portions 16.

As a resin magnet, a nylon resin magnet containing 60% by volume of anisotropic ferrite powder is generally used, but resins such as EVA and PE can also be used.

Effect of invention The advantages of the present invention are as follows.

(a) High magnetic flux density can be obtained.

(b) It is easy to integrate the magnet and shield material.

(c) Features such as ease of molding of anisotropic resin magnets can be effectively utilized.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing a conventional example of a magnet equipped with a shield plate, Fig. 2 is a cross-sectional view of a magnet without a shield plate, Fig. 3 is a cross-sectional view showing the characteristics of an anisotropic magnet, and Fig. 4 is a cross-sectional view showing the characteristics of an anisotropic magnet. FIG. 5 is a cross-sectional view showing a model of the magnetic circuit of the magnetic device of the present invention, FIG. 5 is a cross-sectional view of a speaker field section used as a conventional example, and FIG. 6 is a cross-sectional view showing an embodiment of the present invention. 12... Anisotropic magnet molded product, 13... Shield member, 14... Cut-and-raised part.

Claims (1)

[Scope of utility model registration request] A magnetic shielding member with high magnetic shielding properties is provided in close contact with one of the surfaces intersecting the orientation direction of the oriented anisotropic resin magnet, and the magnetic shielding member has a cut-and-raised part formed by cutting and raising a part of the magnetic shielding member. and a magnetic device using an anisotropic magnet in which the cut and raised portion is integrated into an anisotropic resin magnet along the alignment direction.