JPS5927603Y2 - Composite mold magnetic core - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a ferrite magnetic core used in choke coils, transformers, etc., and particularly relates to a ferrite core whose surface is coated with molded ferrite.

Conventionally, ferrite magnetic cores have been used as magnetic cores for high-frequency choke coils, transformers, etc., but as their range of applications has expanded, products that are close to the low frequency range and complex shapes are increasingly required. .

Generally, sintered ferrite is manufactured through pressure forming and firing processes, and is large enough to meet the above requirements.
In the case of a corner object with an uneven shape (for example, a drum-shaped core), it is extremely difficult to form it and it is difficult to meet the requirements, so it is necessary to use a silicon steel plate material or a simple shape that is easy to form even if the same ferrite core material is used. Alternatively, the ferrite core can be machined to obtain the desired shape, or the ferrite that has been fired is powdered and mixed with a binding material such as resin and molded into the desired shape to create a so-called resin. We have responded to these demands with products such as ferrite, molded ferrite, and powder magnetic cores.

However, the above conventional means have drawbacks such as limited frequency range, increased manufacturing man-hours such as assembly and processing, and deterioration of magnetic properties such as μ, so none of them completely satisfies the requirements in terms of price, performance, etc. was not obtained.

This invention effectively solves the above-mentioned problems, and aims to provide a composite molded magnetic core that is large in size, can be adapted to various magnetic core shapes, and has excellent electromagnetic properties.

In other words, the gist of this invention is that a cylindrical sintered ferrite magnetic core is arranged in the core, and that at least a part of the surface of the sintered ferrite magnetic core is formed so that the mixing ratio of sintered ferrite powder and resin is set at a predetermined level. The present invention relates to a composite molded magnetic core, characterized in that a drum is formed by being coated with a molded ferrite made of a mixture of the above molded ferrite and provided with a flange portion serving as a coil winding recess so that the wire can be directly wound on the molded ferrite. It is something.

Examples of this invention will be described below with reference to the drawings.

FIG. 1 shows a cross-sectional view of the first embodiment of this invention, showing a magnetic core having a drum-shaped outer shape. A cylindrical sintered ferrite magnetic core is used.

A molded ferrite 2 is formed on at least a part of the surface of the ferrite magnetic core 1.

This molded ferrite 2 is made by mixing a predetermined amount of resin 2a and sintered ferrite powder 2b, for example, at a ratio of 1:3 by weight, and is injection molded through, for example, a heating cylinder (screw) (not shown).

A coil (winding wire) is wound around the flange portion formed by molded ferrite in this manner.

3 shows a winding when used as an inductor.

The structural feature of this device is that the main body of the magnetic core is a ferrite having excellent magnetic performance, such as a cylindrical sintered ferrite magnetic core 1, and is formed into a desired external shape, such as a drum shape. The outer surface of the sintered ferrite magnetic core 1 is coated with a mixed material of resin 2a such as acrylic and sintered ferrite powder 2b, which is easy to mold and has excellent machining adaptability. The purpose is to obtain a composite molded magnetic core 4 having a desired shape by integrally press-bonding or injection molding.

By applying a winding 3 and the like to this magnetic core 4, a desired coil or transformer can be obtained.

Next, FIGS. 2a and 2b are cross-sectional views of the second embodiment of this invention,
A perspective view is shown in which a composite molded magnetic core 4 of this invention is attached to a predetermined portion of a molded ferrite 2 formed in the same manner as in the first embodiment, for example, for attaching and fixing it to another substrate (not shown). The molded ferrite 2 is molded so that a mounting part 6 with a screw hole 6a etc. is formed in the molded ferrite 2 itself, and in addition to the above-mentioned effects, it has a particularly large magnetic core that makes it difficult to use materials such as mounting brackets. Costs are saved.

FIG. 3a shows a sectional view of a third embodiment of this invention, in which a threaded means 7a is simultaneously formed on a part of the molded ferrite 2 during molding, and a cylindrical composite molded magnetic core 8 is formed. The separately prepared disk-shaped composite molded magnetic core 9 provided with the screwing means 7b corresponding to the screwing means 7a is used in combination, and even if the means of this invention shown above is used. Furthermore, it is suitable for realizing ultra-large composite molded magnetic cores that are difficult to perform simultaneous molding operations in one go, and also facilitates partial processing and assembly.

FIG. 3 shows a partial cross-sectional view of a fourth embodiment of this invention, in which a cylindrical composite molded magnetic core 10 having a screwing means 7a formed in the central hole is formed in a part of the molded ferrite 2. The inductance can be adjusted by using a separately prepared bar-shaped composite molded magnetic core 11 provided with a screwing means 7b corresponding to the screwing means 7a as a trimmer core, which is more significant than the conventional trimmer inductor. The structure is effectively simplified, the two screwing means are made of the same material and have the same temperature coefficient, the screwing precision is high, the cost is high, the reliability is high, and the inductance changes smoothly.

FIG. 4 shows a sectional view of a fifth embodiment of this invention, in which a predetermined portion of the molded ferrite 2, for example, an end portion 1 is shown.
Ferrite powder 2 in mold ferrite 2 in 2
The heating cylinder (
The sintered ferrite powder 2b added to the screw) is stopped, and only the resin 2a is introduced in the middle of molding, and the end portion 12
An electrical connection terminal 14 connected to the winding 3 is attached to the coil 3, and the good insulation properties of the resin 2a in the molded ferrite 2 and the ease of implanting the terminal 14 are effective.

Moreover, it is possible to prevent magnetic coupling with other parts.

As is clear from the above examples, the effect obtained by this invention is that a sintered ferrite magnetic core in a single quasi-shape such as a cylinder or cylinder, which is relatively easy to mold, is arranged in the core, and A composite molded magnetic core with excellent mechanical and electromagnetic properties can be obtained by integrally pressuring or injection molding the outer shape of the magnetic core with a molding material made of a mixture of a binder such as a resin and ferrite powder. In particular, magnetic cores with large and complex shapes can be obtained at low cost and with good performance.

Moreover, when attempting to obtain a sintered ferrite core in the conventional drum shape, etc., due to the complexity of its shape, it is difficult to prepare a complicated mold, adjust pressure, or require cutting work. However, it has been recognized that with this invention, it is possible to obtain a magnetic core with a desired external shape by injection molding, for example, with the same ease as using a general resin mold, and that it is also possible to obtain a magnetic core with high dimensional accuracy. It was done.

Also, because the outer surface of the composite molded magnetic core obtained in this way is coated with molded ferrite, mechanical damage such as chips and cracks, which are disadvantages of ordinary sintered ferrite magnetic cores, does not occur. It has excellent insulation properties without damaging the windings, and has much better magnetic properties such as μ than those made entirely of resin ferrite.

As described above, this invention is a useful invention that can provide a composite molded magnetic core having many advantages, and is also an invention that will greatly contribute to the electronic component industry.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the first embodiment of this invention, Figure 2 a, l
) is a sectional view and perspective view of the second embodiment of this invention, FIG. 3a is a sectional view of the third embodiment, FIG. 3 is a partial sectional view of the fourth embodiment, and FIG. Similarly, it is a sectional view of the fifth embodiment. FIG. 4 is a sectional view of the fifth embodiment. 1... Ferrite magnetic core, 2... Molded ferrite, 2a... Resin, 2b...
・Ferrite powder, 4.8゜9.10.11...
・Composite mold magnetic core, 6...Mounting part, 7a, 7
b... Screwing means, 12... End portion, 14
・・・・・・Electrical connection terminal.

Claims (5)

[Scope of utility model registration request] (1) A cylindrical sintered ferrite magnetic core is arranged in the core, and at least a part of the surface of the sintered ferrite magnetic core is mixed with a predetermined mixing ratio of sintered ferrite powder and resin. 1. A composite molded magnetic core characterized in that a drum is formed by being coated with a molded ferrite consisting of a body and having a flange portion serving as a coil winding recess so that a wire can be directly wound on the molded ferrite. (2) The composite molded magnetic core according to claim 1, wherein the molded ferrite is partially formed with a mounting portion having a screw hole. (3) The composite molded magnetic core according to claim 1, wherein the molded ferrite is partially formed in combination with corresponding screwing means prepared separately. (4) The molded ferrite is formed such that the average mixing ratio of ferrite powder and resin in a predetermined part thereof is different from that in other parts. Composite mold magnetic core. (5) The mixing ratio of the ferrite powder to the resin in the predetermined portion is extremely low (including zero), and the predetermined portion is provided with an electrical connection terminal. Composite molded magnetic core according to item 4.