JP2535251Y2 - Induction magnet - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction magnet such as a choke or a transformer in which a core is divided into a plurality of cores.

[0002]

Conventionally, as a high-frequency choke or a transformer, as shown in FIG. 9, a core 50 made of a soft magnetic material magnetized
There is a split-type core (hereinafter, referred to as a split-type core) that is divided into a plurality of sections by a division plane traversing the air circuit A. This split core
A choke or transformer with 50 is easier to insert into a coil by inserting each split core 51, 51 into a coil 52, 52 wound on a bobbin in advance, compared to one in which a closed magnetic circuit is formed by an undivided core. Since the cores 51, 51 can be attached to the 52, 52, there is an advantage that the cost is low.

[0003]

However, in the above-mentioned split type core, it is necessary to avoid air gaps due to the presence of minute irregularities and cracks in the contact surfaces 64, 65 between the split surfaces 54 of the core 50. Therefore, the magnetic permeability of the entire core decreases. Therefore, for example, if the dividing surface 54 in FIG. 9 is formed in a step shape so as not to be orthogonal to the magnetic circuit A, the dividing surface 54 becomes wider, so that the contact area between the divided cores 51, 51 becomes larger and the magnetoresistance becomes larger. Is expected to decrease. However, if the dividing surface 54 is stepped, it is difficult to polish the dividing surface 54, and it is difficult to secure the gap accuracy between the dividing surfaces 54, 54. This is necessary and disadvantageous in terms of cost. Therefore, it has been common sense that all of the divided surfaces 54 of the conventional split core 50 are formed on a plane orthogonal to the magnetic circuit A.

On the other hand, Japanese Utility Model Laid-Open No. 2-56424 discloses a structure in which a rust-preventive oil containing magnetic fine particles is interposed between the divided surfaces of a divided core. Is expected to be reduced to some extent. However, according to common sense, the split surface is formed by a plane orthogonal to the magnetic circuit, so that the contact area between the split cores does not increase, so that the magnetic resistance of the entire core does not sufficiently decrease. Therefore, if the effective magnetic permeability is increased in the divided core to obtain a large inductance with the same number of turns of the coil, the sectional area of the core must be increased, and the core becomes large.

The present invention has been made in view of the above-mentioned conventional problems. In an induction ceramic having a split core, the effective magnetic permeability of the induction ceramic is increased by increasing the contact area between the split cores. The purpose is to obtain a large inductance.

[0006]

In order to achieve the above object, according to the present invention, there is provided an induction magnet having a split type core, wherein at least a part of the split surface of the core is provided in a magnetic circuit passing through the core. Fine particles made of a ferromagnetic material having a particle diameter capable of forming a magnetic fluid are interposed between the two divided surfaces. The particle size of the fine particles,
It is usually 1 μm or less, for example, several tens to several hundreds of angstroms.

[0007]

According to the first aspect of the present invention, at least a part of the dividing surface of the core has a displacement portion which crosses or obliquely intersects with the magnetic circuit passing through the core, so that it is orthogonal to the magnetic circuit. The area is larger than in the conventional case where the surface is flat. In addition, since the ferromagnetic fine particles are interposed between the two divided surfaces, the ferromagnetic fine particles enter minute irregularities and cracks between the two divided surfaces to fill the air gap. Here, since the ferromagnetic fine particles have a small particle size, they do not widen the air gap. Therefore, the substantial contact area between the split cores increases.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. 1 to 3 show a choke according to a first embodiment of the present invention. In FIG. 1, a core 50 is a magnetic circuit.
It is composed of E-shaped split cores 51, 51 which are divided into two by a split plane that traverses A.
52, 52 are wound. The coils 52, 52 are wound in balance so that the magnetic fields generated by the current from the input source are in opposite directions. 2 split cores 5
1 and 51 are pressed against each other in the direction of arrow P by a compression spring (not shown). The split cores 51, 51 are formed in a step shape having a displacement portion (step portion) 18 parallel to the magnetic circuit A, and the split cores 51, 51 have the same shape. Since the split cores 51, 51 are not polished, they have a surface roughness of 20 to 100 μ.

As shown in the enlarged view of FIG.
Ferromagnetic fine particles 10 having a particle size sufficient to form a magnetic fluid are interposed between G between 1, 51 (hereinafter, referred to as “gap”). The two split cores 51, 51 in FIG.
The adhesive (fixing means) 11 made of an epoxy resin or a silicone resin is applied to several places on the outer periphery of the divided surface 54 in FIG.

Next, a method of manufacturing the above-mentioned chalk will be described. First, a coil 52 wound on a bobbin (not shown)
Is attached to the split core 51. On the other hand, the magnetic fluid 12 of FIG. 2 manufactured by, for example, a coprecipitation method is applied to each of the divided surfaces 54 and 54. After this application, the divided cores 51, 51 are lightly pressed against each other, and the divided cores 51, 51 are adhered to each other with the adhesive 11 at several places as shown in FIG. After this bonding, even if the dispersant (solvent) 14 in the magnetic fluid 12 in FIG. 2 evaporates with time, the fine particles 10 remain in the gap G in a state where they adhere to the surface of the gap G.

Here, the magnetic fluid 12 is a ferromagnetic fine particle 10 which is stably dispersed using a surfactant and is dispersed at a high concentration in the dispersant 14, and has magnetic properties. A substance that behaves as a fluid. As the magnetic fluid 12,
For example, oxide magnetic fluid containing 10 to 25% by volume of ferromagnetic fine particles 10 (for example, manganese zinc ferrite magnetic fluid), metal magnetic fluid such as nickel or cobalt,
An iron nitride magnetic fluid or the like can be used. As the dispersant 14 for the magnetic fluid 12, water or the like can be used in addition to petroleum-based kerosene and paraffin. The ferromagnetic fine particles 10 usually have a particle size of 1 μm or less.
A few hundred angstroms is preferred.

In the above configuration, since the dividing surfaces 54, 54 are stepped, a planar dividing surface orthogonal to the magnetic circuit A is provided.
Compared with 14 (broken line), the contact area between the split cores 51, 51 increases. Here, although the surface roughness of the divided surface 54 is high, the ferromagnetic fine particles 10 in the magnetic fluid 12 enter the cracks C and the irregularities H of the gap G between the divided surfaces 54, 54, and the gap G is reduced. fill in. Moreover, since the particle diameter of the fine particles 10 is small, the gap G does not widen. Therefore, the magnetic permeability of the gap G is significantly improved. That is, the magnetic resistance between the divided surfaces 54 greatly decreases. Actually, when the magnetic fluid 12 containing the iron nitride fine particles 10 is used, the magnetic permeability of the whole core 50 in FIG. 1 recovers to 99% when the relative magnetic permeability of the undivided core is about 10,000. did. On the other hand, when a magnetic fluid is inserted into the division surface 14 orthogonal to the magnetic circuit A, the magnetic permeability recovers to 80% to 85% at most.

The recovery of the magnetic permeability was obtained irrespective of the presence or absence of evaporation of the dispersant 14 (FIG. 2) in the magnetic fluid 12. As described above, the magnetic permeability of the entire core 50, that is, the effective magnetic permeability is restored, so that the magnetic resistance is reduced and the inductance is increased when the number of coil turns is the same. Therefore, the characteristics of the choke are improved. In addition, although the magnetic fluid is required, the division surface 54 is not polished, so that there is no possibility that the total cost will be significantly increased. Furthermore, two split cores 51,
Since 51 has the same shape, it is superior in mass productivity as compared with the case of different shapes.

In this embodiment, two divided cores 5
1, 51 are bonded to each other by the adhesive 11, but it is not always necessary to bond them. When the divided cores 51 and 51 are not adhered to each other, the magnetic permeability is slightly reduced when an impact force is applied to the core 50 after the dispersant 14 in the magnetic fluid 12 in FIG. 2 evaporates. This is because the impact force is applied to the core 50,
It is presumed that this is caused by a slight change in the state (shape) of the gap G (FIG. 2) as the two split cores 51, 51 are slightly displaced in the X direction or the Y direction in FIG. On the other hand, as shown in the embodiment of FIG.
When 1, 51 are fixed to each other, even if an impact force is applied,
Since there is no possibility that the two split cores 51 are displaced from each other, the magnetic permeability does not decrease. Therefore, when used in an environment that is susceptible to impact force, it is preferable that the two split cores 51, 51 be fixed to each other by fixing means (adhesive 11).

As a method for injecting the magnetic fluid 12 shown in FIG. 2 into the gap G, there is a method utilizing the capillary phenomenon described below, in addition to the method using the above-described coating. This method will be described with reference to FIG. After the magnetic fluid 12 is filled into the dropper S, when the tip opening S1 of the dropper S is pressed against the outer periphery of the dividing surface 54, the magnetic fluid 12 in the dropper S enters the gap G (FIG. 2) due to capillary action. invade. Further, when a direct current is applied to the coils 52, 52, the magnetic fluid 12 receives a magnetic force and completely enters cracks C and irregularities H in the gap G in FIG.

FIG. 4 shows a second embodiment of the present invention. In FIG. 4, the magnetic fluid 12 is interposed between the divided surfaces 54, 54. The outer periphery of the core 50 on the division surface 54 is closed by a sealing material 15 made of, for example, epoxy resin or silicone resin. Therefore, the dispersant 14 in the magnetic fluid 12 is sealed in the gap G of FIG. 2 so as not to evaporate. In this embodiment, since the magnetic fluid 12 is sealed in the gap G, even if an impact force is applied to the core 50 and the divided cores 51 and 51 are displaced from each other and the state of the gap G changes, Ferromagnetic fine particles 10 suspended in dispersant 14
Enters the changed gap G. Therefore, even if an impact is applied, the magnetic permeability does not decrease.

FIGS. 5 and 6 show a third embodiment of the present invention. As shown in FIG. 6, a filling adhesive 17 obtained by mixing ferromagnetic fine particles 10 into a resin 16 is interposed and solidified between the divided surfaces 54, 54 in FIG. Therefore, both split cores
51 and 51 are joined to each other by the cured resin 16.
As described above, as an example of a method of interposing and curing the filling adhesive 17 in the gap G, first, a ferromagnetic fine particle 10 is suspended in a monomer of a thermosetting resin 16 as a dispersant. A fluid (filling adhesive 17) is injected into the gap G. Next, the resin 16 is heated and solidified by a polymerization reaction.

In this embodiment, since the filling adhesive 17 obtained by mixing the ferromagnetic fine particles 10 into the resin 16 is interposed and solidified in the gap G, the divided cores 51 and 51 are solidified.
Mechanically firmly joined. Therefore, even when an impact force is applied to the core 50, the two split cores 51, 51 do not shift from each other. In addition, at the time of injection or application,
54 Ferromagnetic fine particles in the irregularities H and cracks C of 54
Since the resin 16 is solidified, the irregularities H
And crack C is maintained. Thus, in this embodiment, the misalignment between the split cores 51, 51 can be prevented, and the ferromagnetic fine particles 10 are kept in the same state as at the time of injection, so that the magnetic permeability may decrease over time. There is no.

In each of the above embodiments, as the ferromagnetic fine particles 10, in addition to manganese zinc-based ferrite and iron nitride powder, ferrite powder containing manganese, iron, nickel, copper, magnesium, etc., and iron A mixed powder of cobalt or the like can be used. In particular, the split core 51,
By using ferrite or iron nitride having a higher magnetic permeability than the ferromagnetic material constituting 51, it is possible to make the magnetic permeability of the entire core 50 close to the magnetic permeability of the undivided core. In particular, it is effective to use a magnetic fluid made of fine particles of iron nitride, and data that does not cause magnetic saturation up to a magnetic flux density of 2,000 gauss has been obtained. It has better magnetic properties than a ferrite magnetic fluid that saturates at a magnetic flux density of several hundred gauss. By concentrating the concentration of the fine particles of iron nitride more than the above-mentioned 10 to 25% by volume, the characteristics of the core which has not been divided can be further brought close to use at a high magnetic flux density.

The ferromagnetic fine particles 10 may be obtained by a chemical synthesis method such as the above-mentioned coprecipitation method, or may be obtained by pulverizing sintered ferrite into fine powder or a metal magnetic material prepared by a vapor phase method. Alternatively, an iron nitride magnetic fluid or the like can be used. Further, in each of the above embodiments, the coil 52 is wound in a balanced manner as shown in FIG. 1, but the number of the coil 52 may be one. Furthermore, while the above embodiments have described high-frequency chokes, the present invention is also applicable to transformers.

In each of the above embodiments, each of the divided cores 51 has an E-shape and the entire core is of the EE type. However, the shape of the entire core 50 is the EI type shown in FIG. 7
The present invention can be applied to the ring type shown in FIG. 7B or the UU type shown in FIG.

Further, the shape of the dividing surface 54 is not limited to a step-like shape, and may be of various types. For example, a quadrangular prism-shaped projection 18A as shown in FIG. 8A, or as shown in FIG. The protrusion 18B may be a triangular prism. In short, the shape of the dividing surface 54 is, as long as at least a part of the displacement portion 18, 18A, 18B intersects or obliquely intersects the magnetic circuit A, as compared with the shape orthogonal to the magnetic circuit A. This is effective because the contact area between them increases.

[0023]

As described above, according to the first aspect of the present invention, the contact area between the split cores 51 is increased without increasing the size of the induction magnet. As a result, the inductance can be increased with the same number of turns of the coil, thereby improving the characteristics of the induction magnet.

[Brief description of the drawings]

FIG. 1 is a perspective view of a choke showing a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view showing a gap of a division surface in FIG.

FIG. 3 is a perspective view showing a method of manufacturing a chalk.

FIG. 4 is a perspective view of a choke showing a second embodiment.

FIG. 5 is a perspective view of a choke showing a third embodiment.

FIG. 6 is an enlarged cross-sectional view showing a gap of the division surface in FIG. 5;

FIG. 7 is a front view showing another example of a core to which the present invention can be applied.

FIG. 8 is a front view of a core showing the fourth and fifth embodiments.

FIG. 9 is a perspective view showing a conventional split core type choke.

[Explanation of symbols]

10: ferromagnetic fine particles, 12: magnetic fluid, 17: filling adhesive, 18: displacement part, 50: core, 51: split (divided) core,
52: coil, 54: split surface, G: gap (between split surfaces), A: magnetic circuit.

Continuation of the front page (56) References Practical application Microfilm (JP, U) photographing the contents of the specification and drawings attached to the application form of Japanese Patent Application No. 63-135185 (Japanese Utility Model Application No. 2-56424)

Claims (1)

(57) [Scope of request for utility model registration] A core 50 around which a coil 52 is wound is a magnetic circuit
Divided cores 51, 51 divided into a plurality of parts by a dividing plane crossing A
In the induction magnet consisting of
Has at least a part thereof intersecting parallel or obliquely with the magnetic circuit A passing through the core 50, and has two divided surfaces 54, 54.
An induction magnet, characterized in that fine particles 10 made of a ferromagnetic material having a particle diameter capable of forming a magnetic fluid 12 are interposed therebetween.