JPH0442906A - Inductor - Google Patents

Abstract

PURPOSE:To enable production to be simple, productivity to be improved, and characteristics to be improved by filling and placing a ferromagnetic body powder around a coil with a ferromagnetic body core material at a hollow core part and then forming a closed magnetic circuit between this powder and the core material. CONSTITUTION:A ferromagnetic body core material 3 is inserted and fixed into a hollow core part of an insulation bobbin 1 which is coil-stranded 2. At this time, an outer-periphery surface of the coil is protected by winding an insulation tape while both end faces of the core material are maintained to be bare. The coil thus constituted is charged into a case 4 which is made of plastic, metal, etc., and a ferromagnetic body powder 5 if filled into a space which is formed between the case 4 and the coil so that the entire coil is surrounded. Finally, an opening of the case is sealed with resin etc. Thus, by using powder as a yoke material, the space part which is formed between these due to flow behavior of the powder can be filled irrespective of the shapes, dimensions and conditions of the core and the case, which is extremely convenient for forming a closed magnetic circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an inductor suitable for use in a low-pass filter for a noise filter or a choke for high-frequency rectification and smoothing.

(Prior Art) Inductors are used as low-pass filters in combination with capacitors to remove noise, and also as chokes for high-frequency rectification and smoothing.

Such inductors usually have a core wrapped around a conducting wire such as a copper wire, and the core shapes vary;
Typical examples include ring-shaped toroidal cores, pot-shaped pot cores, EE cocoa, and EI cocoa, which have a shape that forms a so-called closed magnetic path that confines most of the magnetic flux generated in the coil inside the core. It has a structure.

In terms of materials, there are metal powder-based dust cores, oxide-based soft ferrite cores, and amorphous ribbon-based amorphous cores, which can be used depending on the purpose by taking advantage of the characteristics of each. It is being

Regarding noise, it is necessary to consider both the prevention of noise generation and noise intrusion prevention, and this applies to fields such as switching power supplies, light control equipment, heat control equipment, speed control equipment, microcomputers, various measuring equipment, and audio/communication equipment. Various noise prevention measures have been taken.

Here, the core shape of the inductor will be specifically explained. ) The loidal type, EE type, and El type are already well known, so their explanation will be omitted, and the urn-shaped pot core will be explained. In the past, the type shown in Figure 2 was often used. However, in recent years, dust type cores and T
The number of mold cores having the shape shown in FIG. 3 (for example, Japanese Utility Model Application Laid-Open No. 60-61708) is rapidly increasing.

Another known technology related to inductors is to mix ferromagnetic powder into an adhesive so that, for example, an E type with a coil attached and a mating T type, a T type also equipped with a coil and a mating C type. A type in which split cores such as
No. 5), or by preforming magnetic powder to obtain a plurality of core pieces, winding a coil around one of the core pieces, then assembling these pieces, and applying more force to the final molding. (Japanese Unexamined Patent Publication No. 59-63809).

In addition, there are those in which a coil is fitted into a mold or case, a mixture of magnetic powder and thermosetting resin powder is poured thereon, and the mixture is heated and cured (Japanese Patent Laid-Open No. 13994/1983); After coil winding is applied to the powder magnetic core with a gap formed therein, direct current is passed through the winding to attract raw magnetic powder of the same quality as the powder magnetic core into this gap, and further impregnated with insulating resin and solidified. (Japanese Patent Publication No. 57-32495), and furthermore, iron powder with insulated particle surfaces is sealed in an annularly shaped insulating resin case to form a closed magnetic path. A toroidal coil (Japanese Unexamined Patent Application Publication No. 1983-1983) is formed by filling the case with a ring-shaped core and winding copper wire in a toroidal shape from the outside of the case.
-20562) and the like are known.

(Problem to be solved by the invention) However, for example, the above-mentioned Utility Model Application Publication No. 60-61708
In the publication, in the inductor manufacturing process, it is necessary to mold two types of cores, C-type and T-type, and in addition, it is necessary to finish the mating surfaces with high precision in order to obtain a good contact condition when assembling. Problems remained in the complicated manufacturing process.

Furthermore, Japanese Patent Application Laid-Open No. 59-63809 similarly had a problem in that the manufacturing process was complicated.

In addition, Utility Model Application Publication No. 59-171315 and Japanese Unexamined Patent Publication No. 54-
When adhesives or resin materials are used as in Publication No. 13994, even though magnetic powder is mixed, the density of the magnetic material in this region is low, so there is a problem that the overall characteristics deteriorate. there were.

The present invention advantageously solves the above-mentioned problems, and aims to propose an inductor that is easy to manufacture, has high productivity, and has good characteristics.

(Means for Solving the Problems) That is, in the present invention, ferromagnetic powder is filled and arranged around a coil having a ferromagnetic core material in a hollow core portion, and a gap between the powder and the core material is This is an inductor that forms a closed magnetic path.

A preferred manufacturing process for such an inductor is as follows.

1. Insert and fix the ferromagnetic core material into the hollow core of the insulating bobbin with the coil wound. At this time, the outer peripheral surface of the coil is
While protecting it by wrapping it with insulating tape, keep both ends of the core material bare.

2. The coil thus constructed is placed in a case made of plastic or metal, and the space formed between the case and the coil is filled with ferromagnetic powder so as to enclose the entire coil.

36 Finally, the opening of the case is sealed with resin or the like. At that time, all necessary measures for the inductor shall be taken, such as drawing out the coil lead wires and embedding fixing pins for attaching the inductor to the board.

In this way, the present invention is characterized in that the periphery of a coil having a ferromagnetic core material that does not form a closed magnetic path is filled with ferromagnetic powder so as to form a closed magnetic path, and a yoke is constructed using this powder. It has characteristics.

This invention will be specifically explained below.

FIG. 1 shows a preferred example of the inductor according to the present invention in longitudinal section, in which number 1 is an insulating bobbin, 2 is a coil winding,
3 is a ferromagnetic core material (hereinafter simply referred to as core), 4 is a case, 5 is ferromagnetic powder, 6 is a sealing part, 7 is a coil lead wire, and 8 is a bare end face of the core. It is.

Although omitted in FIG. 1, it goes without saying that in addition to this, a fixing bin for mounting the inductor and a protective coating on the outer periphery of the coil winding (performed with tape or the like) are required.

Now, in the case shown in Figure 1, it is sufficient to use an ordinary plastic bobbin as the insulating bobbin 1, but if heat generation of the core becomes a problem, use a heat-resistant bobbin 1. is necessary for winding, but core 3
Q: It is also possible to directly apply an insulating coating or to wrap an insulating tape, and then wind a coil on top of that. Furthermore, in the case of an essentially insulating material such as a ferrite core, winding may be applied directly onto the core 3. However, with this bobbin 1, not only is it easier to wind the wire, but the core preparation and coil winding can proceed in parallel, and the process can be shortened by assembling the bobbin and core at the end.
“Manufacture” – convenient. Furthermore, if this insulating bobbin 1 is used, there is no need for insulating coating on the core 3, which eliminates the occurrence of defective products due to coating.
Another advantage is that the core yield is improved. Of course, it goes without saying that the coil winding can be automated by using the bobbin 1.

As the core 3, any material may be used, including a dust core of a metallic powder magnetic core, a soft ferrite fired magnetic core, and a metallic wire-wound magnetic core such as an amorphous ribbon or a crystalline ribbon. , is a ferromagnetic material, and both end surfaces 8 are insulated.1. Any item that is naked and not exposed is suitable. Moreover, this end surface does not necessarily have to be a flat surface, and may be an uneven surface or a curved surface. Further, the shape of the core is not particularly limited, and may be prismatic, cylindrical, cylindrical, or any other shape. However, it goes without saying that cylindrical or disc-shaped ones are usually easier to use, and the magnetic path length and cross-sectional area of the core can be taken into account when determining force, = size, and shape.

Next, the outer case 4 may be made of metal, plastic, or any other material, and its material and shape do not matter. If insulation must be considered, it is desirable to examine the material accordingly. Of course, plastic is usually sufficient.

The inductor of the present invention is magnetically sealed with ferromagnetic powder, so even if a plastic case is used, there will be no loss due to sensitivity to nearby conductive objects.

The material of the ferromagnetic powder 5 to be filled next can also be selected arbitrarily. That is, any ferromagnetic powder such as iron powder, alloy powder such as sendust or permalloy, amorphous alloy powder, and soft ferrite powder may be used. Furthermore, the particle shape, particle size, etc. are not particularly limited and can be used over a wide range of applications.7 When filling the ferromagnetic powder 5, it is desirable to increase the degree of filling by tapping or the like.

(Function) The greatest feature of this invention is that a closed magnetic path is formed by connecting both end surfaces of the core using ferromagnetic powder. By using powder as the yoke material in this way, no matter what the shape, size, or condition of the core or case (e.g. occurrence of cracks or chips), the fluidity of the powder will prevent the formation of particles between them. This is extremely convenient for forming the intended closed magnetic circuit, and this is an important point.

Another advantage of using powder is that, for example, if we take an iron powder-based Dasure core, in this case it is not necessary to use iron powder as the powder, but rather soft Ferrite I. Using powder not only improves the step and inductance, but also because soft ferrite powder is originally an insulator, there is no need to insulate the wire and fixing bottle, and the filling powder itself This is advantageous in that it can be used in any combination with the core material.In other words, it has another significance in that it allows a greater degree of freedom in the product when manufacturing inductors.

It should be noted that different types of powder may be mixed and used as needed, and therefore the degree of freedom is increased.

In this regard, in the aforementioned Utility Model Application Publication No. 60-61708,
It is necessary to mold both the C-shaped core and the T-shaped core, and when combining the two, precision of the fitting surface is required, so a rough solution as in the present invention cannot be expected.

Note that this invention is not applicable only to pot-shaped pot cores, but as long as the requirements of this invention are satisfied, that is, ferromagnetic powder is used as a yoke to form a closed magnetic circuit. It can also be applied to other cores including type cores.

(Example) m = outer diameter: 13. Omn+, inner diameter: 8. Om+a, height: 8.3 a+a+.

The inner and outer surfaces of an iron powder-based toroidal dust core with a density of 6.3 g/cm" are coated with epoxy resin to a thickness of 0.35 m, and the outer periphery of this core is coated with a diameter of 0.35 m.
After winding 10 turns of copper wire with a length of 100 m, insulation tape was wrapped around the outside of the winding. Next, after insulating the lead wire part with a vinyl tube, this coil was installed with inner dimensions: 19+
After loading it into the center of a plastic cylindrical container of smφ, 15 md with the axial direction aligned, the surrounding area was filled with iron powder, and then a plastic lid was placed to seal the lead wire extraction part. Sealed.

When the inductance of the thus obtained inductor was measured at IV and 1 kHz using an impedance analyzer, a value of 11.1 μH was obtained.

In this example, the inner diameter side of the core was also filled with iron powder, but this does not have a particularly important meaning.

For reference, the entire outer peripheral surface of an iron powder-based toroidal dust core in exactly the same condition as that used in Example 1 was coated with epoxy resin to a thickness of 0.35 m, and a 0.35 mφ copper wire was coated on this. It was wound in a normal toroidal shape for 10 turns.

The inductance of this coil was measured using the same measuring device and under the same conditions as in Example 1, and found to be 5.9 μH.

As is clear from the comparison between Example 1 and Comparative Example 1 above,
Despite using cores of the same size, density, and material, the inductor of the present invention exhibited higher inductance.

In Example 1, the iron powder filled around the core was removed and the inductance was measured in the same manner as in Example 1, and was found to be 3.2 μH.

Thus, it can be seen that the inductance is low in the core that does not form a closed magnetic path.

The inductance of the inductor manufactured in the same manner as in Example 1 except that the copper wire was dispersioned in 16 turns was 27.9 μH, which was the same as in the case of a normal toroidal core. It was proportional to the square of the number of windings.

In Example 1, the ferromagnetic powder to be filled was Mn.
- When the inductance of an inductor produced was changed to Zn-based soft ferrite powder and all other conditions were the same as in Example 1, it was found to be 13.8 μH.

In this way, the inductance changes depending on the type of filling powder, and soft ferrite powder was found to be particularly effective.

An insulating tape was wrapped around the outer circumferential surface of an iron powder-based doublet-shaped dust core having an outer diameter of 11.3 mm, a height of 11.7 Il+m, and a density of 6.3 g/cm', and a 0.0 mm insulating tape was placed on top of it. A coil was created by winding 20 turns of 6-diameter copper wire and then wrapping insulating tape on top of it. This coil was placed in a plastic container with inner dimensions: 22 + ymφ and 25 mmH with the axial direction aligned, and then iron powder was filled around it, and the lid was then closed in the same manner as in Example 1. An inductor was manufactured using the following steps.

The inductance of the obtained inductor was measured under the same conditions as in Example I, and a value of 51.9 μH was obtained.

Note that the magnetic path cross-sectional area of the dust core portion constituting this inductor is ICII+''.

Stop comparison outer diameter: 31.5mm, inner diameter 718.5++uw, height: 16. Oa+m.

The entire outer peripheral surface of an iron powder-based toroidal dust core having a density of 6.3 g/ctn3 was coated with epoxy resin 17 to a thickness of 0.35 m1, and then coated with epoxy resin 0.6 m as in Example 4.
An inductor was manufactured by winding a copper wire of 20 turns in a triangular shape.

When the inductance of the obtained inductor was measured under the same conditions as in Example 4, it was found that although the magnetic path cross-sectional area of this toroidal coil was the same IC as in Example 4, the inductance was 46. It showed a value of 3 μm1, which was actually lower than that of Example 4.

Example 41 - Mutual - In Example 4, the ferromagnetic powder to be filled was changed from iron powder to MnZn-based soft ferrite powder, although all other conditions were the same as in Example 4. , 60° showed an inductance of 4 μH.

X beauty-example outer diameter = 51. Wrap insulating tape around the outer periphery of the cylindrical part, excluding both end faces, of the Mn-Zn soft ferrite core with a height of near au+.
After winding 0 turns, this coil has inner dimensions: 10Iφ
, 15 mail (with the same axial direction), and then the space formed by the coil and the container was filled with iron powder so as to surround the coil.The coil winding surface was Then, an insulating tape was rolled up to protect it.Then, the bottom surface was sealed in the same manner as in Example 1 to produce an inductor.

When the inductance of the obtained inductor was measured under the same conditions as in Example 1, it was found to be 22.1 μH.

In this embodiment, both of the two lead wires are drawn out from the bottom of the container, but there is no problem in drawing them out from the upper and lower surfaces of the container, depending on the purpose and necessity.

In Example 6, the ferromagnetic powder to be filled was changed from iron powder to Mn-Zn soft ferrite powder, and although all other conditions were the same as in Example 6, the inductance was It became 36.0 μH.

As can be seen from the comparison between Example 6 and Example 7 above,
The characteristics also change depending on the type of filler powder used to form the yoke. This phenomenon is similar to the case of the comparison between Example 1 and Example 3 described above, but the effect of the soft ferrite core is greater than that of the iron powder dust core.

12, fl↓ In Example 6, the filled iron powder was removed and a closed magnetic path was formed.1. When the inductance was measured under the same conditions as in Example 6, it was found to be only 5.4 μH.

This also shows how important the presence of ferromagnetic powder as a yoke material for forming a closed magnetic path is.

Note that in Examples 1 to 6, a bobbin was not used for the coil winding portion due to experimental reasons, but it goes without saying that manufacturing is easier if a bobbin is used from an industrial perspective. We also examined the frequency characteristics, and found that the trends were the same as those of ordinary toroidal coils.

(Effects of the Invention) As described above, the inductor according to the present invention not only has better characteristics than conventional inductors, but can also be easily miniaturized if necessary.

Further, in its production, it is possible to automate and shorten the process, and therefore, a significant improvement in productivity can be expected.

Furthermore, it goes without saying that the inductor of the present invention can be used not only as a noise filter but also as a smoothing choke coil, and its applications and uses are wide-ranging.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a preferred inductor according to the present invention, FIGS. 2(a) and 2(b) are longitudinal sectional views and contact surfaces of a conventional pot core, respectively, and FIG. 3(a) ,(
B) is a separate vertical cross-sectional view and a diagram illustrating a fitted state of a conventional pot core, respectively. 1... Insulated bobbin 2... Coil winding 3...
・Ferromagnetic core material 4...Case 5...Ferromagnetic powder 6...Sealing part 7...Coil lead wire 8...Same as bare core end face

Claims (1)

[Claims] 1. An inductor in which a coil having a ferromagnetic core material in a hollow core is filled with ferromagnetic powder, and a closed magnetic path is formed between the powder and the core material.