JPH0521232A - Inductance element - Google Patents

Abstract

PURPOSE:To provide an E-shaped inductance element which eliminates the waste of a magnetic substance at a part of low flux density and reduces hysterisis loss and extra heat generation. CONSTITUTION:One lower core 1A of a pair of cores forming a magnetic core is composed of a middle leg part 11, a middle leg side bottom part 12, a recessed bottom part 13, an outer side bottom part 14, a tilting part 15, an outer part 16, a bottom tilting part 17 and a bottom part 18. These planes form a concentric circle. The other upper core 1B is constituted similarly. In a conventional E-shaped core, a corner part of low flux density is cut off and the bottom tilting part 17 is provided and the tilting part 15 is formed as compensation thereof. A recessed bottom part 13 is formed to compensate for a size of a coil engagement space 19 which is reduced by formation of the tilting part 15. It is desirable to recess a lower part of the middle leg part 11 of the bottom part 18. Thereby, hysterisis loss in a part of a low flux density is reduced and heat generation is also reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inductance element used for a magnetic core (core), and in particular, as an E-type magnetic material for a switching power supply, the material thereof is reduced, loss is reduced, and heat generation is suppressed. The present invention relates to a magnetic core inductance element.

[0002]

2. Description of the Related Art Although various types of inductance elements are known as magnetic core inductance elements, when forming a highly efficient inductance element, a coil (winding) is used.
In many cases, two E-shaped (or pot-shaped) inductance elements having a shape of wrapping with a core are butted and integrated to form a magnetic core.

FIG. 6 shows a cross-sectional view of a conventional standard E-type core inductance element. This inductance element is integrally configured by combining a pair of lower inductance element 7A and upper inductance element 7B and fitting a coil (not shown) in the interior 78 thereof. One of the inductance elements, for example, the lower inductance element 7
A is integrally constituted by a base portion 72, a middle foot portion 71 standing upright at the center of the base portion 72, and an outer shell portion 73 standing upright on the outer shell of the base portion 72, and its cross-sectional area shape is the letter E of the alphabet. Since it is similar,
It is called an "inductance element for mold core". E shown in FIG.
In the type core inductance element, a coil is fitted in the lumen 74 defined by the pair of inductance elements 7A and 7B, and the magnetic flux passes through the inductance elements 7A and 7B as shown by the arrow in the figure.

[0004]

In the inductance element of FIG. 6, even if the magnetic path cross section of the same magnetic potential is taken, the magnetic flux density differs depending on the place. The magnetic flux density is high in a portion having a short magnetic path and a large magnetic resistance value, for example, in the magnetic path A inside the drawing, and in a portion having a long magnetic path and a small magnetic resistance value, for example, in the magnetic path B outside the drawing. It shows a low tendency. Particularly, a portion having a long magnetic path and a small magnetic resistance value, that is, outer corners 75 and 77 of the base portion 72, a connecting portion between the base portion 72 and the middle foot portion 71 on the inner cavity 74 side at positions symmetrical to these portions, Connection part 7 between base part 72 and outer shell part 73
In No. 8, the cross-sectional area is large, and the magnetic flux density in these parts is considerably low. This means that almost no magnetic flux passes through this low magnetic flux density portion, and the magnetic material in those portions is not being effectively used, which is a problem that the magnetic material is wasted. There is. From another perspective, this waste of magnetic material also means that the size of the inductance element is increased, and when this inductance element is applied to a switching power supply, the size of the switching power supply is large. This also causes the problem of being against the miniaturization of switching power supplies. Furthermore, the useless magnetic material increases the hysteresis loss, and the amount of heat generated by the entire magnetic core increases. Such a problem also causes a problem of increasing the ambient temperature of the switching power supply when the inductance element is applied to a transformer of the switching power supply. Therefore, it is an object of the present invention to solve the above problems, to provide an inductance element having a reduced size, which minimizes hysteresis loss and heat generation.

[0005]

In order to solve the above problems, in the present invention, a portion of the inductance element where substantially no magnetic flux passes is removed so that the magnetic flux density becomes uniform in the inductance element. .. That is, the inductance element of the present invention prevents the middle foot portion, the connection portion between the middle foot portion and the base portion, the base portion, the connection portion between the base portion and the outer shell portion, and the outer shell portion from having a low magnetic flux density. Are formed continuously, and the respective cross-sectional areas are formed to have substantially the same size.

[0006]

The magnetic flux density becomes substantially uniform when the one-cycle magnetic path of the inductance element forming the magnetic core is continuous without waste and the cross-sectional areas thereof are uniform. As a result, there is no wasted magnetic material portion, no extra hysteresis loss occurs, and extra heat generation is suppressed.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An E-type core inductance element according to a first embodiment of the present invention is shown in FIGS. Figure 1 (A) is (B)
2B is a cross-sectional view of the inductance element taken along line XX in FIG. 4B, and FIG. 6B is a plan view taken along line HH in FIG.
FIG. 2 is a partially enlarged view of FIG. The core inductance element 1 of the first embodiment is configured by combining a pair of lower inductance element 1A and upper inductance element 1B. The lower inductance element 1A and the upper inductance element 1B are symmetrical. A coil (not shown) is fitted in a coil fitting space 19 formed between the lower inductance element 1A and the upper inductance element 1B, and is used as a transformer of a switching power supply, for example.

The lower inductance element 1A includes a middle foot portion 1
1, middle foot side bottom 12, concave bottom 13 recessed from the central bottom 12, outer side bottom 14 having the same bottom surface as the center side bottom 12, inclined portion 15, outer portion 16, bottom inclined portion 17, bottom It has a section 18. Middle foot side bottom 12, concave bottom 13, outer shell side bottom 14, inclined portion 15, bottom inclined portion 1
7 and the bottom portion 18 form a base portion. As shown in the plane in FIG. 1B, the middle foot portion 11, the middle foot side bottom portion 12,
The recessed bottom portion 13, the outer side bottom portion 14, the inclined portion 15 and the outer side portion 16 are formed concentrically. However, it does not form a complete concentric circle, and the width becomes narrower from the periphery toward the midfoot part 11. This missing shape in the central portion is a shape resulting from the removal of an unnecessary portion of the magnetic material. if,
If necessary due to the size of the magnetic flux, the inductance element can be formed in a completely concentric shape.

A shape comparison between the conventional inductance element shown in FIG. 6 and the inductance element of FIG. 1 will be described with reference to FIGS. 1 (A) and 2. FIG. 2 is an enlarged view of the left half of the lower inductance element 1A of FIG. 1 (A). As shown by the broken line in FIG. 2, the inductance element shown in FIG. 6 has a corner 20 at the bottom of the outer shell 16, and the bottom surface of the base is defined by the bottom reference line 21 shown by the broken line. Was. On the other hand, in the inductance element of the present invention, the corner portion 20 is omitted and the bottom inclined portion 17 is formed. Then, the inclined portion 1 is formed by removing the corner portion 20.
5 is formed so as to project into the coil fitting space 19. The formation of the inclined portion 15 reduces the size of the coil fitting space 19 to reduce the cross-sectional area of the coil fitted therein, thereby preventing the generated magnetic flux from decreasing, and thus forming the recessed bottom portion 13. Has been done. Therefore, the coil is designed to enter the concave bottom portion 13. By forming the bottom sloped portion 17 by omitting the corner portion 20 and forming the sloped portion 15 parallel to the sloped portion 17, it becomes easier for the magnetic flux to pass near the sloped portion 15 and the magnetic flux on the short magnetic path side. The density is improved, and the magnetic flux density is improved as a whole of the inductance element 1A.

Since the inductance element 1A has a structure in which the magnetic flux density is improved as a whole, the cross-sectional area forming the magnetic path can be made small, and the size of the inductance element 1A can be made practically small. The cross-sectional area of the middle foot portion 11 and the cross-sectional area of the bottom portion which is continuous with the middle foot portion 12, the bottom portion of the middle foot 12, the recessed bottom portion 13, the outer bottom portion 14 and the bottom portion 18 are substantially equal and further inclined The cross-sectional area between the part 15 and the bottom inclined part 17 and the cross-sectional area of the outer shell part 16 are also equal to the cross-sectional area of the midfoot part 11. That is, the cross-sectional area of the magnetic path has a substantially uniform size. Further, as described above, the formation of the inclined portion 15 has a smaller volume than the lack of the corner portion 20, so that the volume (size) of the inductance element 1A can be reduced.

Since the magnetic circuit has a substantially uniform circular cross-sectional area, the magnetic flux density has a substantially uniform distribution in the magnetic path, and the above-mentioned inductance element in which the corner portion 20 is omitted and the concave bottom portion 13 is formed is conventionally used as a magnetic body. It exhibits the same performance as the inductance element of and does not deteriorate in performance. Ie, therefore,
When the coil is fitted in the coil fitting space 19, the magnetic flux generated in the coil is not reduced. On the other hand, since there is no unnecessary portion such as the corner portion 20, there is no hysteresis loss in that portion, and heat generation is reduced. Further, by removing the corner portion 20, it is possible to prevent the corner portion from being chipped. Usually, when manufacturing a magnetic core, the magnetic powder is enclosed in a mold, press-molded, then sintered, and finally butt-polished with the other core. Stress concentration occurs in the and often chipping occurs, and this chipping may increase. However, by omitting the corner portion 20 as described above, this problem disappears.

A modified example of the inductance element of the first embodiment is shown by a broken line in FIG. That is, the inner inclined portion 12a is formed in place of the middle foot side bottom portion 12, and the inner foot portion 11
The bottom part 18 of the lower part is recessed by the amount of the inner inclined part 12a formed. The distance d from the corner of the metatarsal bottom 12 before the inner inclined portion 12a is formed to the base portion 18 and the distance d1 from the inner inclined portion 12a to the concave surface of the bottom portion 18 are substantially equal to each other. There is no change in the cross-sectional area of the connection between 11 and the base. The concave portion of the bottom portion 18 is a portion having a low magnetic flux density as described with reference to FIG. Further, since the connecting portion of the middle foot side bottom portion 12 with the middle foot portion 11 has an angle of 90 degrees and the magnetic flux is hard to pass through, the magnetic flux density is low around it. Therefore, by removing the concave portion of the bottom portion 18 and forming the inner inclined portion 12a by that much, the distribution of the magnetic flux density of the short magnetic path is further improved, the hysteresis loss is reduced, and the heat generation is reduced. Further, by forming a recess (recess) in the bottom portion 18, for example, when this lower inductance element 1A is applied to a transformer of a switching power supply, for example, a protrusion to be inserted into this recess on a printed circuit board. By providing (not shown), it is possible to accurately position the switching power supply or the like on the printed circuit board or to firmly fix the switching power supply or the like.

FIG. 3 shows an inductance element according to the second embodiment of the present invention. 3 (A) and 3 (B) are respectively shown in FIG.
It corresponds to (A) and (B). This inductance element shows only the lower inductance element 3A. The lower inductance element 3A includes the middle foot portion 31, the middle foot side bottom portion 32, the inclined portion 33, the recessed bottom portion 34, the inclined portion 35, the outer shell side bottom portion 36, and the outer shell portion. 37, a bottom inclined portion 38, a bottom portion 39, and a bottom central recess 40. Centering around the middle foot portion 31, a middle foot side bottom portion 32, an inclined portion 33, a concave bottom portion 34, an inclined portion 35, an outer shell side bottom portion 36, and an outer shell portion 37 are concentrically formed. The inductance element of this embodiment is
This is a further improvement of the inductance element of the first embodiment, in which the middle foot portion 31, the base portion, and the outer portion 37 are continuously formed so that the flow of the magnetic flux becomes smooth, and the overall magnetic flux density becomes uniform. As you can see, the cross sections are almost the same.

The inductance element of the second embodiment is shown in FIG.
This is a shape in which the portion with a low magnetic flux density, which was pointed out with reference to, is almost eliminated. That is, a large concave portion is formed in the lower base portion of the middle foot portion 31 to define a bottom central concave portion 40, and a corner of the lower base portion of the outer shell portion 37 is also largely deleted to define a bottom inclined portion 38. ing. As a result, the magnetic flux density is distributed almost uniformly throughout the magnetic path. In addition, since there is no part with a low magnetic flux density, hysteresis loss is greatly reduced and extra heat generation due to hysteresis loss is also very small. When the lower inductance element 3A is applied to a transformer of a switching power supply, the bottom center recess 40 is used for positioning the switching power supply on the printed circuit board, or the bottom center recess 40 is disposed on the printed circuit board. It can be used to firmly fix the switching power supply by inserting the protrusion.

It should be noted that instead of connecting the connecting portion between the middle foot portion 31 and the middle foot side bottom portion 32 in FIG. 3 (A) at 90 degrees as shown in the figure, the inner slope shown by the broken line in FIG. 1 (A) By providing an inclined portion like the portion 12a, the continuity of the cross-sectional area can be improved.

FIG. 4 is a sectional view of the lower inductance element 4A according to the third embodiment of the present invention. The lower inductance element 4A has a shape close to the numeral "3" by further promoting the continuity of the E-shape shown in FIG. 3 and simplifying the shape. The lower inductance element 4A includes a middle foot portion 41, an inclined portion 42, a base portion upper surface 43, an inclined portion 44,
It is defined by the outer portion 45, the bottom inclined portion 46, the base bottom 47, and the bottom central recess 48. Also in this lower inductance element 4A, the portion with a low magnetic flux density is deleted,
It is formed in a continuous shape as a whole, and the cross-sectional areas are almost the same. Therefore, also in the lower inductance element 4A, the above-described effects can be obtained.

FIG. 5 shows a sectional view of a lower inductance element 5A according to a fourth embodiment of the present invention. The lower inductance element 5A has a middle foot portion 51, a base portion 52, an outer shell portion 53, and a corner portion 54 and a bottom center recessed portion 55 are removed. The lower inductance element 5A lacks continuity as compared with the one described above, but has a simple shape suitable for mold manufacturing. Since the corner portion 54 and the bottom center concave portion 55 are the portions having the lowest magnetic flux density, by removing these portions, the lower inductance element 5A also has the above-mentioned dimensional advantages, reduction of hysteresis loss, etc. The effect can be obtained.

In forming the inductance element of the present invention, in addition to the above-described shape, various modifications are taken in consideration of conditions such as the shape of the coil to be fitted and the magnitude of magnetic flux density. be able to. Moreover, the inductance element of the present invention is not limited to the application to the transformer of the switching power supply described above, but can be applied to various devices. For example, such an inductance element itself can be directly arranged on a printed circuit board and used as a transformer.

[0019]

As described above, the inductance element of the present invention eliminates the unnecessary portion having a low magnetic flux density to prevent waste of the magnetic material and reduce the hysteresis loss. There is an advantage that extra heat generation can be reduced with the reduction of loss. In addition, the inductance element of the present invention has an advantage in that the edge portion is cut off, so that no chipping occurs during press molding or the like. Further, by forming a recess at the bottom of the middle foot of the bottom of the base of the inductance element of the present invention, useless magnetic material can be reduced, and the recess can be used for positioning and the like. The effect is obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing an inductance element according to a first embodiment of the present invention, in which (A) is a sectional view taken along line XX of (B) and (B) is a line of (A). It is the top view seen from HH.

FIG. 2 is a partially enlarged view of FIG.

3A and 3B are diagrams showing an inductance element according to a second embodiment of the present invention, in which FIG. 3A is a sectional view taken along line XX in FIG. 3B, and FIG. 3B is line A in FIG. It is the top view seen from HH.

FIG. 4 is a sectional view of an inductance element according to a third embodiment of the present invention.

FIG. 5 is a sectional view of an inductance element according to a fourth embodiment of the present invention.

FIG. 6 is a cross-sectional view of a conventional inductance element.

[Explanation of symbols]

1 ... Inductance element, 1A ... Lower inductance element, 1B ... Upper inductance element, 11 ... Midfoot part, 1
2 ... Middle foot side bottom, 13 ... Recessed bottom part, 14 ... Outer shell bottom part, 15 ... Inclined part, 16 ... Outer shell part 17 ... Bottom sloped part, 18 ... Bottom part, 19 ... Coil fitting Mounting space, 20 ... Corner, 21 ... Bottom reference line, 3A ... Lower inductance element, 31 ... Midfoot, 3
2 ・ ・ Midfoot side bottom part, 33 ・ ・ Inclined part, 34 ・ ・ Recessed bottom part, 35 ・ ・ Inclined part,
36 ... Outer side bottom 37 ... Outer side, 38 ... Bottom sloping part, 39 ... Bottom part, 40 ... Bottom center recessed part.

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[Procedure amendment]

[Submission date] June 3, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

[Invention]

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inductance element using a magnetic core, and in particular, as a magnetic part such as a switching power supply, the material is reduced, loss is reduced, and heat generation is suppressed. The present invention relates to a magnetic core inductance element.

[0002]

2. Description of the Related Art Various shapes of inductance elements
Are known, the case of forming the inductance element of the high efficiency, the coil (winding) the wrapped with core shape E-type (or pot type) integrated magnetic core 2 butt to Lee
It is often used as a inductance element .

FIG. 6 shows a cross-sectional view of a conventional standard E-type core inductance element. This inductance element is formed integrally by combining a pair of lower core 7A and upper core 7B and fitting a coil (not shown) inside the core 78. One of the cores of the inductance element, for example, the lower core 7A, is integrally configured by a base portion 72, a middle foot portion 71 that stands up at the center of the base portion 72, and an outer shell portion 73 that stands up in the outer shell of the base portion 72. However, since its cross-sectional area shape is similar to the letter E of the alphabet, it is called “ E-type core ” below. The E type connector shown in FIG.
In the inductance element using the coil, a coil is fitted in the lumen 74 defined by the pair of cores 7A and 7B,
The magnetic flux passes through the cores 7A and 7B as shown by the arrows in the figure.

[0004]

In the inductance element of FIG. 6, even if the magnetic path cross section of the same magnetic potential is taken, the magnetic flux density differs depending on the place. The magnetic flux density is high in a portion where the magnetic path is short and the magnetic resistance value is small , for example, in the magnetic path A inside the drawing, and in a portion where the magnetic path is long and the magnetic resistance value is large , for example, in the magnetic path B outside the drawing. It shows a low tendency. Particularly, the portion having a long magnetic path and a large magnetic resistance value, that is, the outer corners 75 and 77 of the base portion 72, the base portion.
In 76, the cross-sectional area is also large , and the magnetic flux density in these parts is considerably low. This means that almost no magnetic flux passes through this low magnetic flux density portion, and the magnetic material in those portions is not being effectively used, which is a problem that the magnetic material is wasted. There is. From another perspective, this waste of magnetic material also means that the size of the inductance element is increased, and when this inductance element is applied to a switching power supply, the size of the switching power supply is large. This also causes the problem of being against the miniaturization of switching power supplies. Furthermore, the useless magnetic material increases the hysteresis loss, and the amount of heat generated by the entire magnetic core increases. Such a problem also causes a problem of increasing the ambient temperature of the switching power supply when the inductance element is applied to a transformer of the switching power supply. Therefore, it is an object of the present invention to solve the above problems, to provide an inductance element having a reduced size, which minimizes hysteresis loss and heat generation.

[0005]

In order to solve the above problems, in the present invention, a portion of the inductance element where substantially no magnetic flux passes is removed so that the magnetic flux density becomes uniform in the inductance element. .. That is, the inductance element of the present invention includes a middle foot portion, a connection portion between the middle foot portion and the base portion, a base portion, a connection portion between the base portion and the outer shell portion, and an outer shell portion in which the magnetic flux density is low and the portion is too high. Are formed continuously so as not to occur, and the respective cross-sectional areas are configured to have substantially the same size.

[0006]

The magnetic flux density becomes substantially uniform when the one-cycle magnetic path of the inductance element forming the magnetic core is continuous without waste and the cross-sectional areas thereof are uniform. As a result, there is no wasted magnetic material portion, no extra hysteresis loss occurs, and extra heat generation is suppressed.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An E-type core inductance element according to a first embodiment of the present invention is shown in FIGS. Figure 1 (A) is (B)
2B is a cross-sectional view of the inductance element taken along line XX in FIG. 4B, and FIG. 6B is a plan view taken along line HH in FIG.
FIG. 2 is a partially enlarged view of FIG. B of the first embodiment
The inductance element 1 is configured by combining a pair of lower core 1A and upper core 1B. Lower core 1A and upper core
It forms a symmetrical and A 1B. Lower core 1A and upper core
A coil (not shown) is fitted in the coil fitting space 19 formed between the 1A and 1B, and is used as a transformer of a switching power supply, for example.

The lower inductance element 1A includes a middle foot portion 1
1, middle foot side bottom 12, concave bottom 13 recessed from the central bottom 12, outer side bottom 14 having the same bottom surface as the center side bottom 12, inclined portion 15, outer portion 16, bottom inclined portion 17, bottom It has a section 18. Middle foot side bottom 12, concave bottom 13, outer shell side bottom 14, inclined portion 15, bottom inclined portion 1
7 and the bottom portion 18 form a base portion. As shown in the plane in FIG. 1B, the middle foot portion 11, the middle foot side bottom portion 12,
The recessed bottom portion 13, the outer side bottom portion 14, the inclined portion 15 and the outer side portion 16 are formed concentrically. However, it does not form a complete concentric circle, and the width becomes narrower from the periphery toward the midfoot part 11. This missing shape in the central portion is a shape resulting from the removal of an unnecessary portion of the magnetic material. if,
If necessary depending on the size of the magnetic flux, the inductance element can be formed in a nearly perfect concentric circle shape.

A shape comparison between the conventional inductance element shown in FIG. 6 and the inductance element of FIG. 1 will be described with reference to FIGS. 1 (A) and 2. FIG. 2 is an enlarged view of the left half of the lower inductance element 1A of FIG. 1 (A). As shown by the broken line in FIG. 2, the inductance element shown in FIG. 6 has a corner 20 at the bottom of the outer shell 16, and the bottom surface of the base is defined by the bottom reference line 21 shown by the broken line. Was. On the other hand, in the inductance element of the present invention, the corner portion 20 is omitted and the bottom inclined portion 17 is formed. Then, the inclined portion 1 is formed by removing the corner portion 20.
5 is formed so as to project into the coil fitting space 19. The formation of the inclined portion 15 reduces the size of the coil fitting space 19 to reduce the cross-sectional area of the coil fitted therein, thereby preventing the generated magnetic flux from decreasing, and thus forming the recessed bottom portion 13. Has been done. Therefore, the coil is designed to enter the concave bottom portion 13. By forming the bottom sloped portion 17 by omitting the corner portion 20 and forming the sloped portion 15 parallel to the sloped portion 17, it becomes easier for the magnetic flux to pass near the sloped portion 15 and the magnetic flux on the long magnetic path side. The density is improved, and the magnetic flux density is improved as a whole of the inductance element 1A.

The magnetic flux density of the core 1A becomes uniform as a whole .
With this structure, the cross-sectional area forming the magnetic path can be reduced, and the size of the core 1A can be actually reduced. The cross-sectional area of the middle foot portion 11 and the cross-sectional area of the bottom portion which is continuous with the middle foot portion 12, the bottom portion of the middle foot 12, the recessed bottom portion 13, the outer bottom portion 14 and the bottom portion 18 are substantially equal and further inclined The cross-sectional area between the part 15 and the bottom inclined part 17 and the cross-sectional area of the outer shell part 16 are also equal to the cross-sectional area of the midfoot part 11. That is, the cross-sectional area of the magnetic path has a substantially uniform size. Further, as described above, the formation of the slanted portion 15 is performed in the corner portion 2
Since the volume is smaller than the loss of 0, the inductance element
The volume (dimension) can be reduced.

Since the magnetic circuit has a substantially uniform circular cross-sectional area, the magnetic flux density has a substantially uniform distribution in the magnetic path, and the above-mentioned inductance element in which the corner portion 20 is omitted and the concave bottom portion 13 is formed is conventionally used as a magnetic body. It exhibits the same performance as the inductance element of and does not deteriorate in performance. Ie, therefore,
When the coil is fitted in the coil fitting space 19, the magnetic flux generated in the coil is not reduced. On the other hand, since there is no unnecessary portion such as the corner portion 20, there is no hysteresis loss in that portion, and heat generation is reduced. Further, by removing the corner portion 20, it is possible to prevent the corner portion from being chipped. Normally, when manufacturing a magnetic core, the magnetic powder is enclosed in a mold, press-molded, then sintered, and finally the abutting surface with the other core is polished. Occasionally, stress concentration occurs at the edge and chipping often occurs, and this chipping may increase. However, by omitting the corner portion 20 as described above, this problem disappears.

A modified example of the inductance element of the first embodiment is shown by a broken line in FIG. That is, the inner inclined portion 12a is formed in place of the middle foot side bottom portion 12, and the inner foot portion 11
The bottom part 18 of the lower part is recessed by the amount of the inner inclined part 12a formed. The distance d from the corner of the metatarsal bottom 12 before the inner inclined portion 12a is formed to the base portion 18 and the distance d1 from the inner inclined portion 12a to the concave surface of the bottom portion 18 are substantially equal to each other. There is no change in the cross-sectional area of the connection between 11 and the base. Recess of the base portion 18, Ru Oh in the lower part of the magnetic flux density as described with reference to FIG. Therefore , by removing the concave portion of the bottom portion 18 and forming the inner inclined portion 12a by that amount, the distribution of the magnetic flux density in the long magnetic path is further improved, the hysteresis loss is reduced, and the heat generation is reduced.
Further, by forming a recessed portion (recess) in the bottom portion 18, for example, when this lower core 1A is applied to a transformer of a switching power supply, for example, a protrusion (inserted into this recessed portion on a printed circuit board) (Not shown),
Precise position of the inductance element on the printed circuit board
It has the effect of being able to make a decision .

The core of the second embodiment of the present invention is shown in FIG.
FIGS. 3A and 3B correspond to FIGS. 1A and 1B, respectively. The inductance element shows only the lower cores 3A, the lower core 3A is midfoot 31, leg-side bottom 32, the inclined portion 33, recessed bottom 34, the inclined portion 35, the outer-side bottom portion 36, outer portion 37, Bottom inclined portion 38, bottom portion 3
9 and a bottom central recess 40. Centering around the middle foot portion 31, a middle foot side bottom portion 32, an inclined portion 33, a concave bottom portion 34, an inclined portion 35, an outer shell side bottom portion 36, and an outer shell portion 37 are concentrically formed. The inductance element of this embodiment is a further improvement of the inductance element of the first embodiment, and the middle foot portion 31, the base portion, and the outer portion 37 are continuously formed so that the flow of magnetic flux is smooth, These cross-sectional areas are almost the same so that the entire magnetic flux density is uniform.

The inductance element of the second embodiment is shown in FIG.
This is a shape in which the portion with a low magnetic flux density, which was pointed out with reference to, is almost eliminated. That is, a large concave portion is formed in the lower base portion of the middle foot portion 31 to define a bottom central concave portion 40, and a corner of the lower base portion of the outer shell portion 37 is also largely deleted to define a bottom inclined portion 38. ing. As a result, the magnetic flux density is distributed almost uniformly throughout the magnetic path. Therefore, the hysteresis loss is greatly reduced, and the extra heat generated by the hysteresis loss is also very small. When the lower core 3A is applied to a transformer of a switching power supply, the bottom center recess 40 is used for positioning an inductance element on the printed circuit board, or the bottom center recess 40 is provided with a protrusion disposed on the printed circuit board. Can be used to firmly fix the inductance element .

It should be noted that instead of connecting the connecting portion between the middle foot portion 31 and the middle foot side bottom portion 32 in FIG. 3 (A) at 90 degrees as shown in the figure, the inner slope shown by the broken line in FIG. 1 (A) By providing an inclined portion like the portion 12a, the continuity of the cross-sectional area can be improved.

FIG. 4 shows a lower core 4A according to the third embodiment of the present invention.
FIG. This lower inductance element 4A is
By further advancing the continuity of the E type shown in FIG. 3, the shape is simplified and the shape is approximated to the numeral “3”. The lower inductance element 4A is defined by the middle foot portion 41, the inclined portion 42, the base portion upper surface 43, the inclined portion 44, the outer portion 45, the bottom side inclined portion 46, the base portion bottom side 47, and the bottom side central recessed portion 48. In this lower core 4A as well, a portion having a low magnetic flux density is removed, and the lower core 4A is formed into a continuous shape as a whole, and has substantially the same cross-sectional area. Therefore, also in this lower core 4A, the above-mentioned effects can be obtained.

FIG. 5 shows a lower core 5A according to a fourth embodiment of the present invention.
FIG. The lower core 5A has a middle foot portion 51, a base portion 52, and an outer shell portion 53, and a corner portion 54 and a bottom center concave portion 55 are removed. Although the lower core 5A lacks continuity as compared with the one described above, it has a simple shape suitable for mold manufacturing. Since the corner portion 54 and the bottom center concave portion 55 have the lowest magnetic flux density, by removing these portions, the lower core 5A also has the above-mentioned dimensional advantages and the effect of reducing hysteresis loss. Can be obtained.

In forming the inductance element of the present invention, in addition to the above-described shape, various modifications are taken in consideration of conditions such as the shape of the coil to be fitted and the magnitude of magnetic flux density. be able to. Moreover, the inductance element of the present invention is not limited to the application to the transformer of the switching power supply described above, but can be applied to various devices.

[0019]

As described above, the inductance element of the present invention eliminates the unnecessary portion having a low magnetic flux density to prevent waste of the magnetic material and reduce the hysteresis loss. There is an advantage that extra heat generation can be reduced with the reduction of loss. In addition, the inductance element of the present invention has an advantage in that the edge portion is cut off, so that no chipping occurs during press molding or the like. Further, by forming a recess in the lower part of the middle foot of the bottom of the base of the core of the present invention, it is possible to reduce wasteful magnetic material and also use the recess for positioning or the like. The effect is obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a core of a first embodiment of the present invention,
(A) is a cross-sectional view taken along line XX of (B),
(B) is a plan view seen from the line HH of (A).

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a diagram showing a core of a second embodiment of the present invention,
(A) is a cross-sectional view taken along line XX of (B),
(B) is a plan view seen from the line HH of (A).

FIG. 4 is a sectional view of a core according to a third embodiment of the present invention.

FIG. 5 is a sectional view of a core according to a fourth embodiment of the present invention.

FIG. 6 is a cross-sectional view of a conventional core .

[Explanation of reference numerals] 1 ... Inductance element, 1A ... Lower core , 1B ... Upper core , 11 ... Midfoot part, 12 ... Midfoot side bottom part, 13 ... Recessed bottom part, 14 ... Outer shell side bottom part , 15 ・ ・ Inclined part, 16 ・ ・ Outer part 17 ・ ・ Inclined bottom part, 18 ・ ・ Bottom part, 19 ・ ・ Coil fitting space, 20 ・ ・ Corner part, 21 ・ ・ Base line, 3A ・ Lower part Core , 31..Midfoot part, 32..Midfoot side bottom part, 33..Inclined part, 34..Concave bottom part, 35..inclined part,
36 ... Outer side bottom 37 ... Outer side, 38 ... Bottom sloping part, 39 ... Bottom part, 40 ... Bottom center recessed part.

Claims (1)

Claim: What is claimed is: 1. An E-type inductance element having a base portion, a middle foot portion which is continuous at the center of the base portion and stands up there, and an outer portion which is continuous at the outer contour of the base portion and stands up there. In the above, the middle foot portion, the connection portion between the middle foot portion and the base portion, the base portion, the connection portion between the base portion and the outer shell portion, and the outer shell portion are continuous and have substantially equal cross-sectional areas. An inductance element characterized by being formed.