JP3194436B2 - Magnetic core - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic core suitable for constructing a coil device such as a small-sized and large-capacity switching power supply transformer.

[0002]

2. Description of the Related Art In recent years, computers and their terminal devices,
With the progress of office equipment and the like, a small, lightweight, thin, and large-capacity switching power supply is required. The most important point in reducing the size and weight of the switching power supply is to make the transformer occupying a large space and weight, especially to reduce the weight and size of the magnetic core constituting the transformer. FIG. 13 is a plan view of a conventional magnetic core known from Japanese Utility Model Laid-Open No. 57-44505, and FIG. 14 is a front view of the same.
The middle leg portion 2 erected on one surface of the bottom plate portion 1 and outer leg portions 31 and 32 erected along the outer peripheral edge of the bottom plate portion so as to surround the middle leg portion 2 are integrated. It is connected to. The middle leg 2 has a circular or square cross section, and is arranged so that the outer peripheral surface thereof is in contact with the side end surface 11 of the bottom plate 1. The outer leg portions 31 and 32 are separated from each other by a notch 33 provided on a side surface opposite to the side end surface 11 with which the outer peripheral surface of the middle leg portion 2 contacts.

In order to construct a switching power supply transformer or the like using the above-mentioned magnetic core, for example, as shown in FIGS. 15 and 16, two magnetic cores A and B having the above structure are used, and Then, the coil 4 is butt-fitted and assembled with the coil bobbin 5 on which the coil 4 is wound. Reference numeral 51 denotes a winding frame portion around which the coil 4 is wound, 52 and 53 are terminal blocks, 54 and 55 are flange portions, and 6 is a terminal implanted on the coil bobbin 5.

[0004]

However, the conventional magnetic core has the following problems. (A) When the cross-sectional shape of the middle leg 2 is circular, the coil 4
Becomes larger, making it difficult to meet the demands for thinning and miniaturization. (B) When the cross-sectional shape of the middle leg 2 is quadrangular, the bobbin 51 of the coil bobbin 5 also has a quadrangular shape, and the coil 4 is wound while being bent at the four corners. For this reason, the winding operation of the coil 4 does not proceed smoothly, and the distance between the coil frame 51 of the coil bobbin 5 and, in turn, the middle leg 2 of the core and the coil 4 increases. It causes deterioration. (C) Since the outer leg portions 31 and 32 are separated from each other by the notch 33 provided on the side surface facing the side end surface 11 with which the outer peripheral surface of the middle leg portion 2 contacts, the flow of the magnetic flux is prevented by the notch 33. There were also problems such as the fact that the shielding effect was reduced.

Accordingly, an object of the present invention is to provide a magnetic core which solves the above-mentioned conventional problems, is suitable for thinning and miniaturization, is easy to wind a coil, has a high shielding effect, and has excellent characteristics. It is to be.

[0006]

In order to solve the above-mentioned problems , a magnetic core according to the present invention comprises a bottom plate portion, a middle leg portion erected on one surface of the bottom plate portion, and a portion on the one surface of the bottom plate portion. And an outer leg portion erected along the outer peripheral edge. The outer leg portion is continuous on both sides located on both sides of the middle leg portion and on one side between the two sides, and an open end is a side end surface of the bottom plate portion.
And an end face located on the same plane as the end face. In the middle leg portion, the directions of the both sides are the major axis direction, both outer peripheral surfaces in the major axis direction are arcuate surfaces, and both the minor axis directions orthogonal to the major axis direction are provided.
It is flat on the side. Appear on both sides in the short axis direction
One of the two planes is a side end surface of the bottom plate portion.
And the other plane is a surface of the bottom plate portion.
Standing up inside . In another aspect, the outer leg
The end face recedes at an angle θ from the side end face of the bottom plate portion.
It may be an inclined surface. In yet another embodiment
The side end faces of the bottom plate are provided on both sides of the middle leg.
Tilting toward the open end of the outer leg.
It may have a slope.

[0007]

[Function] Since the outer leg is continuous on both sides located on both sides of the middle leg and on one side between the two sides, the outer leg portion continuously surrounds the middle leg from three directions. Become. For this reason, the flow of the magnetic flux becomes smooth, and the shielding effect on the coil mounted on the middle leg is enhanced. Outer leg
The open end is flush with the side end surface of the bottom plate.
Thin and compact because of the end face
Can be.

The middle leg has a long-axis direction on both sides and a short-axis direction perpendicular to the long-axis direction. Therefore, the short-axis direction coincides with the height direction, thereby achieving a reduction in thickness and size. be able to. The middle leg is in the short axis direction, which is orthogonal to the long axis direction.
Two flat sides, appearing on both sides in the short axis direction
One of the planes is flush with the side end face of the bottom plate.
Position the middle leg in the plane of the bottom.
Therefore, it is possible to achieve a reduction in thickness and size. The other plane is the bottom plate
Up in the plane of the part, secure the coil winding space.
Can be maintained.

[0009] Since the outer peripheral surfaces in the long axis direction of the middle leg portion are arcuate surfaces, when the coil is wound, it can be smoothly wound without sharp bending. For this reason, the coil winding operation becomes easy, and the separation distance between the coil and the middle leg is reduced, so that excellent characteristics can be obtained. End of outer leg
Is an inclined surface that recedes at an angle θ from the side end surface of the bottom plate
In the case of the embodiment, in combination with the coil bobbin,
Escape of angle θ occurs. For this reason, the magnetic core and coil bobbin
Between the bobbin and the coil bobbin.
So that the magnetic core can be smoothly inserted and fitted
Become. Also, make sure that the side edges of the bottom plate
The slope that recedes toward the open end of the outer leg.
If you have, also incline in combination with the coil bobbin
Surface escape occurs. For this reason, the magnetic core and coil bobbin
Between the bobbin and the coil bobbin.
So that the magnetic core can be smoothly inserted and fitted
Become.

[0010]

1 is a plan view of a magnetic core according to the present invention, and FIG. 2 is a front view of the same. 13 and FIG.
The same reference numerals as those shown above indicate identical components.
The outer leg portion 3 is continuous on both sides located on both sides of the middle leg portion 2 and on one side 12 between both sides. On both sides located on both sides of the middle leg 2, open ends 301 and 302 are opened on the side end surface 11 of the bottom plate 1. Therefore,
The outer periphery 3 continuously surrounds the middle leg 2 from three directions. For this reason, the flow of the magnetic flux becomes smooth, and the shielding effect on the coil (see FIGS. 15 and 16) mounted on the middle leg 2 is enhanced.

The middle leg 2 has an open end 301 of the outer leg 3,
The direction of both sides where 302 is located is the major axis direction X, and the direction orthogonal thereto is the minor axis direction Y. Therefore, the short-axis direction Y can be made to coincide with the height direction, and a reduction in thickness and size can be achieved. In the drawing, both sides in the short-axis direction Y are arc-shaped surfaces 21, 2.
The planes 23 and 24 are continuous with each other. Short axis direction Y
Of the two planes 23 and 24, the plane 23 on the side end face 11 side is located on the same plane as the side end face 11. With such a structure, the overall height becomes a height based on the flat surface 23, so that the thickness is further reduced.

The middle leg 2 has arcuate surfaces 21 and 22 on both sides in the major axis direction X. With such a structure,
When the coil is wound (see FIGS. 15 and 16), the coil can be wound smoothly without sharp bending. For this reason, the coil winding work becomes easy, and the separation distance between the coil and the middle leg 2 is reduced, so that excellent characteristics are obtained.

FIG. 3 is a plan view of another embodiment of the magnetic core according to the present invention, and FIG. 4 is a front view of the same. Middle leg 2
Are arcuate surfaces 21 and 22 on both sides of the open ends 301 and 302 of the outer leg 3 in the long axis direction X, and arcuate surfaces on both sides in the short axis direction Y orthogonal to the long axis direction X. Since the planes 23 and 24 cut out the virtual extensions E1 and E2 of the parts 21 and 22, when winding the coil (see FIG. 15), the coil can be smoothly wound without a sharp bend. For this reason, the coil winding work becomes easy, and the separation distance between the coil and the middle leg 2 is reduced, so that excellent characteristics are obtained.

FIG. 5 is a plan view of another embodiment of the magnetic core according to the present invention, and FIG. 6 is a front view of the same, in which chamfered portions a and b are provided at the edge of the side end surface 11 of the bottom plate 1. . With such chamfered portions a and b, when molding is performed using a ferrite material, mold release of the molded product from the press die is improved, and the occurrence of chipping or breakage at the corner portion is prevented. . In addition, since the chamfered portions a and b receive the press molding pressure on the surface, the press molding pressure is sufficiently distributed,
The pressing pressure and the packing density are made uniform. For this reason, variations in the magnetic characteristics of the bottom plate portion 1 indicating an important position as a magnetic path are prevented, and the performance and yield are improved. Furthermore, Sharp. Since the edge portion disappears and becomes an obtuse edge, the coil end is not damaged at the edge portion, and the performance and yield of the product are improved. Further, damage to the press die is prevented, and the life of the die is prolonged.

FIG. 7 is a plan view of another embodiment of the magnetic core according to the present invention, and FIG. 8 is a front view of the same, in which the middle leg 2 is in the longitudinal direction X of the open ends 301 and 302 of the outer leg 3. Are formed on both sides in the short-axis direction Y, and the planes 23 and 24 are formed by cutting out the virtual extensions E1 and E2 of the arc surfaces 21 and 22 on both sides in the short axis direction Y. An example in which chamfered portions a and b are provided at the edge of the side end surface 11 is shown.

FIG. 9 is a plan view of another embodiment of the magnetic core according to the present invention, and FIG. 10 is a front view of the same. In FIG. The example shown in FIG. With such a structure, an escape of the angle θ occurs in combination with the coil bobbin. For this reason, it is possible to prevent the magnetic core and the coil bobbin from being hooked, and to smoothly insert and fit the magnetic core inside the coil bobbin.

FIG. 11 is a plan view of another embodiment of the magnetic core according to the present invention, and FIG.
Are arcuate surfaces 21 and 22 on both sides of the open ends 301 and 302 of the outer leg 3 in the long axis direction X, and imaginary extensions E1 and E2 of the arcuate surfaces 21 and 22 on both sides in the short axis direction Y. In the shape of the cut-out planes 23 and 24, of the side end surface 11 of the bottom plate 1, both sides of the middle leg 2 are inclined surfaces 111 and 112 that recede at an angle θ.

[0018]

As described above, according to the present invention, the following effects can be obtained. (A) Since the outer leg portion is continuous on both sides located on both sides of the middle leg portion and on one side between both sides, the flow of magnetic flux is smooth, and the outer leg portion has a high shielding effect on the coil mounted on the middle leg portion. Can provide a magnetic core. (B) The center leg has a long axis direction on both sides and a short axis direction in a direction perpendicular to the long axis direction. Therefore, it is possible to provide a magnetic core suitable for reduction in thickness and size. (C) Since the outer peripheral surfaces in the major axis direction of the middle leg portion are arcuate surfaces, coil winding work is easy, and the separation distance between the coil and the middle leg portion is small, and the characteristics are excellent. Can provide a magnetic core.

[Brief description of the drawings]

FIG. 1 is a plan view of a magnetic core according to the present invention.

FIG. 2 is a front view of a magnetic core according to the present invention.

FIG. 3 is a plan view of another embodiment of the magnetic core according to the present invention.

FIG. 4 is a front view of the magnetic core according to the present invention shown in FIG. 3;

FIG. 5 is a plan view of still another embodiment of the magnetic core according to the present invention.

FIG. 6 is a plan view of still another embodiment of the magnetic core according to the present invention.

FIG. 7 is a plan view of still another embodiment of the magnetic core according to the present invention.

FIG. 8 is a front view of the magnetic core according to the present invention shown in FIG. 7;

FIG. 9 is a plan view of still another embodiment of the magnetic core according to the present invention.

FIG. 10 is a front view of the magnetic core according to the present invention shown in FIG. 9;

FIG. 11 is a plan view of still another embodiment of the magnetic core according to the present invention.

FIG. 12 is a front view of the magnetic core according to the present invention shown in FIG. 11;

FIG. 13 is a plan view of a conventional magnetic core.

FIG. 14 is a front view of a conventional magnetic core.

FIG. 15 is a cross-sectional view of the coil device using the conventional magnetic core shown in FIGS. 11 and 12.

16 is a cross-sectional view taken along line C1-C1 of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bottom plate part 2 Middle leg part 3 Outer leg part 21 and 22 Arc surface 23 and 24 Plane

Claims (2)

(57) [Claims] A magnetic core having a bottom plate, a middle leg erected on one surface of the bottom plate, and an outer leg erected along an outer peripheral edge on the one surface of the bottom plate. The outer leg portion has an end surface which is continuous on both sides located on both sides of the middle leg portion and one side between the two sides, and whose open end is located on the same plane as a side end surface of the bottom plate portion. In the middle leg portion, the directions of the both sides are the major axis direction, both outer peripheral surfaces in the major axis direction are arcuate surfaces, and both sides in the minor axis direction orthogonal to the major axis direction are planes. And two planes appearing on both sides in the short axis direction, one plane is located on the same plane as the side end face of the bottom plate part, and the end face of the outer leg part is the end face of the bottom plate part. A magnetic core that is an inclined surface that recedes at an angle θ from the side end surface. 2. A magnetic core having a bottom plate, a middle leg erected on one surface of the bottom plate, and an outer leg erected along an outer peripheral edge on the one surface of the bottom plate. The outer leg portion has an end surface which is continuous on both sides located on both sides of the middle leg portion and one side between the two sides, and whose open end is located on the same plane as a side end surface of the bottom plate portion. In the middle leg portion, the directions of the both sides are the major axis direction, both outer peripheral surfaces in the major axis direction are arcuate surfaces, and both sides in the minor axis direction orthogonal to the major axis direction are planes. And two planes appearing on both sides in the short axis direction, one of which is located on the same plane as the side end face of the bottom plate part, and the side end face of the bottom plate part is on both sides of the middle leg part. The magnetic core having an inclined surface that recedes toward an open end of the outer leg.