JPH04340209A - Coil and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide the title coil capable of being easily formed into a core taking various shapes as well as the manufacturing method thereof. CONSTITUTION:In the title coil 26 provided with windings 16, 18 and a core 30 arranged in the central parts of the windings 16, 18, the core 30 is composed of magnetic body particles. In such a constitution, the magnetic body particles can be formed into various shapes.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coil and a method of manufacturing the same, and more particularly to a coil comprising a winding and a core disposed at least at the center of the winding, and a method of manufacturing the same.

0002

2. Description of the Related Art Conventionally, a coil has a winding formed by winding an electric wire around a bobbin, and a central core made of a magnetic material that is inserted through the center of the winding. In addition, field cores made of magnetic materials to close magnetic circuits depending on the purpose, etc.
There are also coils that are provided with a casing, and on the other hand, there are coils that do not have a bobbin in the winding. The central core and field core are formed by processing a core material made of a stack of rods or plates made of hard magnetic material (for example, iron or ferrite).

0003

[Problems to be Solved by the Invention] However, the above-mentioned conventional coils have the following problems. Since the core is formed by processing a core material made of a stack of rods and plates made of hard magnetic material, there is a problem in that processing is time-consuming. In particular, for example, if the place where the coil is installed is a space with a complex shape and the core needs to be shaped in a special shape to accommodate the coil in the space, or the magnetic circuit has a special configuration. If the core needs to have a special shape in order to have a special configuration, it is necessary to process the core into a special shape. Such processing is often difficult, and there are problems in that it hinders improvement in coil productivity and causes an increase in production costs. Therefore, an object of the present invention is to provide a coil whose core can be easily formed and which can be formed into various shapes, and a method of manufacturing the same.

0004

[Means for Solving the Problems] In order to solve the above problems, the present invention has the following configuration. That is, in a coil comprising a winding and a core disposed at least at the center of the winding, the core is made of magnetic powder. Further, in this coil, the core may include a magnetic powder mixed with a binder for solidifying the magnetic powder. On the other hand, a method for manufacturing such a coil is characterized by comprising a step of forming a winding wire, and a step of putting magnetic powder into at least the center of the winding wire to form a core.

[0005]

[Action] The action will be explained. Since the core is made of magnetic powder, it can be formed into any shape. In particular, when the core is formed by mixing magnetic powder with a binder for solidifying the magnetic powder, no means for maintaining the shape of the core is required. In addition, in the case of a manufacturing method that includes a step of forming a winding wire and a step of forming a core by putting magnetic powder into at least the center of the winding wire, since the magnetic powder has fluidity, it is easy to The core can be formed into a desired shape.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In this embodiment, an iron core type transformer incorporating a coil according to the present invention will be described as an example. In FIG. 1, 10 is an inner bobbin, which is made of synthetic resin (for example, epoxy resin). The shape of the inner bobbin 10 is shown in FIG. 2(a). Four terminal pins 12 made of a conductive material are integrally provided at the lower end of the inner bobbin 10. Also, inner bobbin 1
A center hole 14, which is a through hole, is bored in the center of 0. Note that for the terminal pins 12, terminals that can be surface mounted may also be used. 16 and 18 are windings (primary coil and secondary coil), and electric wire (magnet wire) 2
0 is wound between the flanges 24 of the inner bobbin 10. The windings 16 and 18 are each wound around the inner bobbin 10 a predesigned number of times, and each end of the wire 20 is connected to the terminal pin 12. FIG. 2B shows a state in which the electric wire 20 is wound around the inner bobbin 10 to form the windings 16 and 18. 22 is an outer bobbin, which is made of synthetic resin (for example, epoxy resin). The outer bobbin 22 is fitted onto the windings 16 and 18 (the state shown in FIG. 2(b)) formed by winding the electric wire 20 around the inner bobbin 10, and protects the windings 16 and 18 to form a coil body 26. ing. FIG. 2C shows the coil body 26 formed by fitting the outer bobbin 22 into the state shown in FIG. 2B. Note that the outer bobbin 22 may be made of metal (for example, iron). In particular, when it is made of metal, which is a magnetic material, it can function as a field core for closing a magnetic circuit.

A casing 28 is made of metal (eg iron) or synthetic resin (eg epoxy resin). The casing 28 is formed into a cup shape, and can accommodate the coil body 26 therein in a loosely fitted state. The appearance of the casing 28 is shown in FIG. 30 is a core, which is a material (core material) that is made of a mixture of magnetic powder (e.g. iron) and a binder (e.g. epoxy adhesive) for solidifying the magnetic powder, which has fluidity before solidification. Consists of. In this example, the weight ratio of the magnetic material and the binder is 97.
However, this weight ratio can be set as appropriate by taking into account the type of magnetic material used, the purpose of the coil, the required characteristics, etc. In this embodiment, as clearly shown in FIG. 1, the core 30 is formed to cover the inside of the center hole 14 of the inner bobbin 10 and the entire outer periphery of the coil body 26.
It forms both the central core and the field core. Generally, the core must be formed at least within the center of the windings of the coil. To form the core 30, first, the coil body 26 is positioned at a predetermined position inside the casing 28 with the open lower end thereof facing up, using a jig or the like. Next, core material is poured into the casing 28. The core material is placed in an amount sufficient to cover the center hole 14 of the inner bobbin 10 and the entire outer circumference of the coil body 26. After pouring the core material, a lid 32 for closing the open lower end surface of the casing 28 is attached and fixed using a known appropriate method (for example, adhesive or caulking).

Like the casing 28, the lid 32 is made of synthetic resin or metal, and has four through holes 34 at predetermined positions through which the terminal pins 12 of the coil body 26 are inserted. Note that if the lid 32 can be fixed by the action of the binder contained in the core material, there is no need to use special means to fix it. After forming the transformer as described above, the magnetic powder contained in the core material is solidified with a binder. Depending on the type of binder, the magnetic material is solidified by natural drying, heat drying, etc. In the case of heat drying, use a temperature that does not dissolve the synthetic resin used for the bobbin etc.
It is necessary to perform the heat treatment at a temperature of preferably 200 degrees Celsius or less). One embodiment of the coil according to the present invention has been described above, and next, another embodiment will be described. For the magnetic material that constitutes the main component of the core material, in addition to the above-mentioned iron, powders of all magnetic materials such as ferrite can be used as long as they can meet the characteristics required for the coil or the product using the coil. It is. As the binder, in addition to the above-mentioned epoxy adhesive, an ultraviolet curing type adhesive may be used. In that case, after the core material is poured, it is irradiated with ultraviolet rays to solidify it. Alternatively, thermosetting resin powder may be mixed with magnetic powder and heated to solidify the core material. In other words, as long as the binder can solidify magnetic powder, any means may be used as long as there is no problem with the coil or the product using the coil.

Up to this point, a mixture of magnetic powder and a binder has been used as the core material, but a binder is not necessarily required as the core material. For example, in the example of FIG.
If the seal between the terminal pin 12, etc. inserted into the through hole 34 is perfectly sealed, it is possible to prevent the core material from flowing out, so there is no need to mix a binder with the core material, and even magnetic powder alone can prevent the core material from flowing out. It can demonstrate its core functions. In addition, apart from the example shown in Figure 1, if a bag-shaped or cylindrical filling body is provided at the center of the winding wire or around the winding wire, and magnetic powder is poured into the filling body and sealed, a binder is not required. . When using a filler, there is an advantage that the filler can be easily formed even if there are complicated restrictions on the shape of the core, as long as the filler can be easily deformed. Next, another embodiment of the core forming procedure will be described. In the above example,
The coil body 26 was placed in the casing 28, and then the core material was poured and the core 30 was solidified, but the casing 28 may not be necessary depending on the coil. In that case, if the filling body is used, the filling body should be placed at the center of the winding and/or
Alternatively, the core may be formed into a desired shape by placing it around the core and pouring (filling) the core material (magnetic powder alone or a material containing a binder) into the filler. Furthermore, as a method for forming the core, a mold can be used, such as resin molding. A pre-formed winding is placed in a mold, similar to insert molding in resin molding, and then the core material is poured into the mold, and the magnetic powder is solidified with a binder to form a core with the desired shape. Form. After the core is formed, the coil is completed by releasing the mold. The shape of the core can be formed into any shape, regardless of whether it is a central core or a field core. moreover,
If the shape is simple, the core material (including a binder) can be filled and/or coated inside and/or around the winding wire and solidified to form a core without taking any special measures. In this case, the core material should have a relatively high viscosity because it will be easier to form the core.

Although various preferred embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments. For example, the winding may be of a type without a bobbin. Of course, many more modifications can be made without departing from the spirit of the invention.

[0011]

[Effects of the Invention] By using the coil and its manufacturing method according to the present invention, since the core is made of magnetic powder, it is possible to form the core into any shape without sintering the powder. Therefore, there are cases where there are restrictions on the shape of the core,
When it is desired to make the magnetic circuit into a desired circuit configuration, it becomes possible to easily match the shape of the core. When the core is formed by mixing the magnetic powder with a binder for solidifying the magnetic powder, there is no need for a means to maintain the shape of the core after the coil is completed. In addition, when the core manufacturing method includes a step of forming a winding wire and a step of forming a core by putting magnetic powder at least in the center of the winding wire, since the magnetic powder has fluidity, This has remarkable effects such as being able to easily form the core into a desired shape.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view of an embodiment of a transformer using a coil according to the present invention.

FIG. 2 is a perspective view showing the appearance of each part of the coil body.

FIG. 3 is an exploded perspective view of the transformer.

[Explanation of symbols]

10 Inner bobbin 14 Center hole 16 Winding wire 18 Winding wire 20 Electric wire 22 Outer bobbin 26 Coil body 28 Casing 30 core

Claims (3)

[Claims] 1. A coil comprising a winding and a core disposed at least at the center of the winding, wherein the core is made of magnetic powder. 2. The coil according to claim 1, wherein the core is made of magnetic powder mixed with a binder for solidifying the magnetic powder. 3. A method for manufacturing a coil, comprising the steps of forming a winding, and forming a core by putting magnetic powder into at least the center of the winding.