JPH11176655A - Coil having magnetic core - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coil comprising a magnetic core that is formed by bending and laminating a magnetic metallic plate so that the soil can be made smaller and thinner that those molded from powder, has a laminate structure, and has less eddy-current loss than those with a single layer magnetic metallic core. SOLUTION: A magnetic core 1 is formed by bending and laminating a magnetic metallic plate copper having an insulating layer on the surface such as permalloy and silicone. A coil having a magnetic core is obtained by applying a winding 2 to this magnetic core. The plate is made about 0.05 to 0.15 mm thick so that a plurality of layers are laminated to make the magnetic core thick enough to gain the required magnetic flux. Owing to the thinness of the plate, the eddy-current loss decreases. A C-shaped magnetic core made by bending a grain-oriented silicon steel can reduce hysteresis loss because the whole magnetic path has the same direction as the rolling direction. The magnetic core can be manufactured efficiently by progressive presswork.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a choke coil such as a booster circuit of an EL drive circuit, and a cored coil such as a transformer.

[0002]

2. Description of the Related Art A few examples of a conventional coil with a magnetic core are shown in FIG. 5. In FIG. 5, a coil having a magnetic core 1 provided with flanges 3 at both ends is manufactured by molding a ferrite powder magnetic material. ,
The winding 2 is wound around this. FIG. 6 is a diagram in which a winding 2 is wound around an I-shaped magnetic core 1 obtained by pressing a metal magnetic material plate such as a permalloy or a silicon steel plate. FIG. 7 shows a coil for a spindle motor. In order to reduce eddy current loss, the magnetic core 1 is formed by laminating a plurality of silicon steel magnetic plates 4 having a thickness of about 0.3 to 0.5 mm. A winding 2 is applied to this, and 5 is a pin provided by half-punching the magnetic plate 4 of each layer, and the half-punch pin 5 is inserted into a half-punched hole of the magnetic plate 4 overlapping above or below. All the magnetic plates 4 are arranged. FIG. 8 also shows a magnetic plate 4 made of a permalloy or silicon steel plate.
Is a coil with a magnetic core in which a winding wire 2 is wound around a magnetic core 1 in which C is laminated, and the shape of the magnetic core is C-shaped.

[0003]

The above-mentioned conventional cored coils have the following problems. That is, in FIG. 5 in which the magnetic core 1 is made of a ferrite-based powder magnetic material, since the magnetic flux density of the powder magnetic material is lower than that of the metal magnetic material, the volume must be increased in order to obtain the same magnetic flux as the magnetic core of the metal magnetic material. And miniaturization is hindered. Also, the production cost of powder molding is higher than pressing a metal plate.

[0006] The magnetic core 1 formed by pressing a metal magnetic material plate as shown in FIG.
However, it is disadvantageous in terms of eddy current loss as described below. The eddy current loss We of the magnetic substance per unit time and unit volume is expressed by the following equation. We = σt ² f ² B ² where σ is a proportionality constant, t is the plate thickness, f is the frequency of the magnetic field,
B is the maximum magnetic flux density. According to this equation, the eddy current loss increases rapidly as the plate thickness increases, and it is effective to reduce the plate thickness to suppress this. Therefore, in the motor coil shown in FIG. 7, the magnetic core 1 is formed by laminating one magnetic plate 4 of a thin silicon steel plate whose surface is insulated. There is a limit in reducing the plate thickness because the magnetic plates are connected to each other, so that the thickness cannot be reduced to 0.3 to 0.5 mm or less as described above, and further thinning, miniaturization, and high performance are difficult. Met. The present invention is directed to overcoming these problems with respect to cored coils.

[0005]

According to the present invention, in a coil containing a magnetic core, a metal magnetic material plate such as permalloy or silicon steel plate whose surface has been subjected to insulation treatment is bent and superimposed on each other so as to have a thickness capable of obtaining a required magnetic flux. Make the core a core. Since this is an integrated structure in which each magnetic plate is connected by a bent part, there is no need to provide a half punch pin on each plate to align separate plates as described above, and the plate thickness is significantly thinner than before. Thus, eddy current loss of the magnetic core can be reduced. Efficiency can be produced by progressive press die in processing.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. Note that the same reference numerals are used for the same kind of parts and parts including the above description. FIG.
Is an embodiment of a cored coil according to the present invention, in which a winding is partially cut out. The magnetic core 1 is a bar-shaped I-shape similar to that of FIG. 6, but it is not a single piece as shown in FIG. 6, but a three-layered magnetic material sheet such as permalloy or silicon steel sheet whose surface is insulated is bent. Is laminated on
The winding 2 is applied to this. The thickness of the magnetic material plate is 0.
It is about 0.05 to 015 mm, and in some cases, it can be smaller. This is much thinner than the conventional 0.3-0.5 mm.

The expanded shape of the magnetic core 1 is as shown in FIG.
There are connecting portions 6 and 7 of each layer on both sides, and the bending lines 8 and 9 are bent in opposite directions. This is a shape in which the I-shape is connected side by side, but as can be easily understood, the development shape of the I-shape magnetic core is, for example, a shape in which the I-shape is vertically stacked, and the boundary of the stack is a bent portion. It is also possible to provide a connection between the layers at a part of the contour of the magnetic core.

In the magnetic core 1 having such a structure, the individual magnetic plates 4 are thin and insulated from each other even if the overall thickness is somewhat large, so that the eddy current loss calculated by the above formula is small. Become. Usually, the surface of the magnetic material plate is oxidized in the process of manufacturing the material to form an insulating layer. However, to ensure reliability, the surface is treated to form an insulating film.

FIG. 3 shows a second embodiment of the present invention, in which the winding is also partially cut away, and the magnetic core 1 is shown in FIG.
The shape of the magnetic core 1 is also a C-shaped one, but the magnetic core 1 is also formed by laminating a magnetic thin plate material into three layers of a magnetic plate 4 and curving both ends into a C-shape to form a winding 2.
Has been given. The developed shape of the magnetic core 1 is as shown in FIG. 4, and there are connecting portions 6 and 7 of each layer at the center, and the bending lines 8 and 9 are bent in opposite directions.

In the case of such a C-shaped magnetic core, the one obtained by bending a thin plate material into the magnetic core 1 according to the present invention has the following advantages in addition to the reduction of the eddy current loss. When the magnetic core material is a grain-oriented silicon steel sheet, the magnetic properties are directional and non-uniform, and when a magnetic field is applied parallel to the rolling direction, the relative magnetic permeability is highest and the hysteresis loss is small. Therefore, for example, in the prior art shown in FIG. 8, if the relationship between the C-shape of the magnetic core 1 punched out of the silicon steel sheet and the rolling direction 10 is as shown in the figure, the core part including the winding part and the void on the opposite side is formed. Although the magnetic path is parallel to the rolling direction 10 and is good, the magnetic path is undesirably perpendicular to the rolling direction at the portion connecting both sides. Even if the improvement is intended, the C-shaped arrangement is inclined at an angle of 45 ° to the rolling direction to average the characteristics.

However, in the case of the present invention, if the length of the developed shape of the magnetic core 1 in FIG. 4 is oriented in the rolling direction 10 of the silicon steel sheet, the C-shaped magnetic path in the completed shape in FIG. The magnetic core has the best magnetic properties. The reduction of the eddy current loss and the reduction of the above-mentioned hysteresis loss due to the reduction in the thickness of the plate can provide a magnetic core which minimizes the iron loss.

The motor coil shown in FIG. 7 is also omitted from the drawing. However, if it is considered that the magnetic plate 4 is provided with a connecting portion with an adjacent layer on a part of the outer periphery thereof and is developed in a chain, it is folded. It can be understood that the stacked cores can be obtained as a whole without using the half blanking pins 5. In order to manufacture the magnetic core of each of the above embodiments, it is of course possible to punch a blank having a developed shape as shown in FIGS. 2 and 4 from a magnetic material plate and to bend it into a completed shape. If a progressive press die is used, a magnetic core of a completed shape can be obtained directly from the strip, and it can be manufactured with extremely high productivity.

[0013]

As described above, the coil with a magnetic core of the present invention has a magnetic core obtained by bending and laminating a plate made of a metallic magnetic material, and is smaller and thinner than a powder-molded coil. Since it is possible and has a laminated structure, the current loss is smaller than that of a single core made of a metallic magnetic material. Compared with the laminated magnetic plate obtained by pressing, there is no need to provide half-punched pins in the magnetic core, so the plate thickness can be made smaller than before, the eddy current loss is smaller, and the magnetic path is curved. In this case, the total length of the magnetic path can be adjusted to the rolling direction of the material, and iron loss is reduced. The cored coil of the present invention is suitable for being manufactured by a progressive press die, whereby a small-sized, high-performance cored coil can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a perspective view of a part of a cored coil according to the present invention.

FIG. 2 is a development view of a magnetic core of the cored coil of FIG. 1;

FIG. 3 is a perspective view of a part of another coil with a magnetic core according to the present invention.

FIG. 4 is a developed view of a magnetic core of the cored coil of FIG. 3;

FIG. 5 is a perspective view of a conventional coil with a magnetic core.

FIG. 6 is a perspective view of another conventional coil with a magnetic core.

FIG. 7 is a perspective view of a conventional motor coil.

FIG. 8 is a perspective view of another conventional coil with a magnetic core.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic core 2 Winding 4 Magnetic plate 5 Half blanking pin 6,7 Connecting part 8,9 Folding line 10 Rolling direction

Claims (4)

[Claims] 1. A coil with a magnetic core having a winding wound on a magnetic core, wherein the magnetic core is formed by bending and laminating a metal magnetic material plate whose surface is insulated. 2. The coil with a magnetic core according to claim 1, wherein the magnetic core is provided with a connection portion between layers at a part of the contour. 3. The coil with a magnetic core according to claim 2, wherein the magnetic core has a rod-like shape, and a connection portion between layers is provided at an end portion. 4. The coil with a magnetic core according to claim 2, wherein the magnetic core has a curved shape at both ends, and a connection portion between layers is provided at a substantially central portion.