JP2021132120A - Magnetic coupling inductor - Google Patents

Abstract

To provide a magnetic coupling inductor capable of attaining downsizing of an external dimension by having a 2-in-1 structure which is functioned substantially as two independent magnetic coupling inductors.SOLUTION: A magnetic coupling inductor comprises: first and second magnetic cores 1 and 2 including middle legs 11 and 21, outer legs 12 and 22 and connection parts 13 and 23; bobbins 4 and 5 through which the middle legs are inserted; first and second coil windings 6 and 7 wound around the respective bobbins; and an annular third magnetic core 3 to which the middle legs are fitted and inserted while being held between both the bobbins. The corresponding legs of the first and second magnetic cores are mutually abutted via gaps, and magnetic fluxes passing the third magnetic core 3 generated by currents passing the first and second coil windings are mutually in the same direction. When a thickness of the third magnetic core 3 is defined as (a) and a gap amount between the outer legs of the first and second magnetic cores is defined as (b), a condition of a≥b is established.SELECTED DRAWING: Figure 2

Description

The present invention relates to a magnetically coupled inductor having a configuration in which an annular core is sandwiched between a pair of PQ cores (including an E core and the like) and a coupling inductor having a 2-in-1 (2in1) structure is provided.

In recent years, a PFC magnetically coupled inductor that realizes a 2-in-1 structure that substantially functions as two independent high-voltage transformers as disclosed in Patent Document 1 below has been proposed, and the external dimensions of the product can be reduced. It is possible.
Further, Patent Document 2 below discloses a transformer configured to sandwich a ring core between a pair of PQ cores.

Patent No. 5062439 Tokusho 4-14487 Gazette

However, in the aspect of these patent documents, depending on the configuration of the combination of the pair of PQ cores and the magnetic core sandwiched between them, the cross-sectional area of the core becomes large in order to pass the synthesized magnetic flux, and the magnetic coupling inductor However, there is a risk that the size will not be sufficiently reduced.

The present invention has been made in view of the above circumstances, has a 2-in-1 structure that substantially functions as two independent magnetically coupled inductors, and optimizes the arrangement conditions related to the combination of each core. It is an object of the present invention to provide a magnetically coupled inductor capable of further reducing the external dimensions.

In order to solve the above problems, the magnetic coupling inductor of the present invention is used.
A first magnetic core and a second magnetic core having a middle leg portion, an outer leg portion located on at least both sides of the middle leg portion, and a connecting portion connecting the middle leg portion and the outer leg portion, respectively. When,
A bobbin through which the first magnetic core and the middle leg portion of the second magnetic core are inserted and arranged on the outside of each of the middle leg portions,
A first coil winding and a second coil winding wound around each of the bobbins,
It is provided with an annular third magnetic core into which the middle leg is fitted while being sandwiched between the two bobbins.
In the first and second magnetic cores, the corresponding legs are abutted against each other, and a gap is provided between each of the corresponding legs.
The magnetic fluxes passing through the third magnetic core generated by the respective currents passing through the first coil winding and the second coil winding are oriented in the same direction.
When the thickness of the third magnetic core is a and the gap amount between the outer legs of the first and second magnetic cores is b.
a ≧ b (1)
It is characterized in that it is configured so that the condition of is satisfied.

Here, when the thickness of the third magnetic core is a and the thickness of the connection portion of the first and second magnetic cores is c,
a ≧ c (2)
It is preferable that the above conditions are satisfied.

Further, it is preferable to provide a positioning fixing member for fixing the intermediate portion in the thickness direction of the third magnetic core at an intermediate position between the tip surfaces of the two middle leg portions.

Further, in the positioning fixing member, a vertical piece extending upward is erected in the center of a flat plate-shaped base portion, slit-shaped engaging grooves are formed on both sides of the inner side of the base portion, and the engaging grooves have slit-shaped engaging grooves. It is preferable that the extension portions of the two inner flange portions of the bobbin are configured so as to be engaged with each other.

According to the magnetic coupling inductor according to the present invention, a two-in-one structure that substantially functions as two independent magnetic coupling inductors is realized while reducing the external dimensions of the magnetic core assembly composed of a combination of a plurality of cores. It is possible. Further, by optimizing the arrangement conditions related to the combination of each core, the external dimensions can be further reduced and the mounting space can be reduced.

It is an overall perspective view of the magnetic coupling inductor which concerns on 1st Embodiment of this invention. It is an exploded perspective view of FIG. 1 excluding the tape. It is sectional drawing of the core part for demonstrating a magnetic loop. It is a partial plan view explaining the arrangement condition of a core structure. It is a partial plan view explaining other arrangement conditions of a core structure. It is sectional drawing for demonstrating the dimensional relationship of the core structure of 1st Embodiment. It is a front view of the core part which shows the other embodiment. It is a perspective view of FIG. 7a. It is a perspective view which shows by removing one PQ core of FIG. 7a. It is a perspective view which shows the combination of two bobbins and a positioning fixing member. It is a perspective view which shows the combined structure of two bobbins. It is a perspective view which shows the combined structure of one PQ core and a positioning fixing member. It is the central sectional front view of the main part. It is the whole perspective view which looked at the magnetic coupling inductor from above. It is a perspective view of the process of winding a coil around a bobbin. It is a perspective view of the process of fixing a positioning fixing member. It is a partial perspective view of the process of combining a core member and a bobbin. It is a bottom perspective view explaining the final bonding process.

Hereinafter, the configuration of the magnetically coupled inductor according to the embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is an external perspective view of the magnetic coupling inductor 100 as a product, and FIG. 2 is an exploded perspective view.

In the magnetic coupling inductor 100 of this embodiment, the first and second magnetic cores 1 and 2 by the PQ core, the third magnetic core 3 by the annular core (ring core), the two bobbins 4 and 5, and the first The second coil windings 6 and 7, two positioning fixing members 8 and 8, eight terminal pins 9 on both sides, and a fixing tape 10 wound around the outer circumference are provided.

The pair of PQ cores of the first magnetic core 1 and the second magnetic core 2 are made of, for example, a ferrite core and have the same external dimensions, and are located on both sides of the middle legs 11 and 21 and the middle legs 11 and 21. The first and second magnetic cores 1 and 2 have outer leg portions 12, 22 and flat plate-shaped connecting portions 13, 23 for connecting the middle leg portions 11, 21 and the outer leg portions 12, 22, respectively. 2 are arranged to face each other.

The middle legs 11 and 21 are columnar, and the length is approximately 1/2 of the distance between the connecting portions 13 and 23 facing each other. The outer legs 12 and 22 have an arcuate inner surface and an outer surface. It has a flat plate shape.

The third magnetic core 3 is made of, for example, a ferrite core and has an annular shape (disk shape) having a rectangular cross section.

The two bobbins 4 and 5 shown in FIG. 8 are made of insulating resin, and both bobbins 4 and 5 have a symmetrical shape, and are integrally combined as shown in FIG. It has terminal blocks 41 and 51, and each terminal block 41 and 51 is provided with four terminal pins 9 and 9, respectively.

The tubular portions 42 and 52 are arranged on the terminal blocks 41 and 51 so as to extend in the axial direction. A disk-shaped outer flange portion 43, 53 is provided at one end on the terminal block 41, 51 side of the tubular portions 42, 52, and a disk-shaped inner flange portion 44, 54 is provided at the opposite end. Positioning restricting members 8 and 8 described later are engaged with the extension portions 44a and 54a extending downward from the inner flange portions 44 and 54, and protrusions 44b and 54b are formed at the lower end portions (see FIG. 9). .. Further, butterfly-shaped protrusions 45 and 55 are provided on the upper and lower ends of the outer flange portions 43 and 53 of the bobbins 4 and 5, and the vertically inclined surfaces of the connecting portions 13 and 23 of the first and second magnetic cores 1 and 2 are provided. It is configured to come into contact with.

As described above, since the butterfly-shaped protrusions 45 and 55 are provided on the upper and lower ends of the outer flange portions 43 and 53 of the bobbins 4 and 5, the first and second coil windings 6 and 7 (including the lead wire) are provided. ) And the first and second magnetic cores 1 and 2, and the magnetic cores 1, 2 and 3 and the bobbins 4 and 5 can be stably fixed to each other.

The ends of the tubular portions 42 and 52 of the bobbins 4 and 5 are provided in a symmetrical concave-convex shape for engagement, and the concave portion 42b of one bobbin 4 is engaged with the convex portion 52a (see FIG. 8) of the other bobbin 5. , The axes of the two tubular portions 42 and 52 are aligned.

The continuous tubular portions 42 and 52 of the bobbins 4 and 5 have the middle leg portion 11 of the first magnetic core 1 from one end side and the middle leg portion 21 of the second magnetic core 2 from the other end side. By inserting each of them, the bobbins 4 and 5 are arranged on the outside of each of the middle legs 11 and 21.

Then, in the first and second magnetic cores 1 and 2, the corresponding middle legs 11 and 21 and the outer legs 12 and 22 on both sides are abutted against each other, and the corresponding legs are each abutted against each other. Gaps G1 and G2 are provided between them (see FIG. 3), and the size b (basically the same dimensions) of the gaps G1 and G2 is defined by the positioning fixing member 8 (so-called spacer) described later.

In the configuration of the bobbins 4 and 5, the first coil winding 6 is wound between the outer collar portion 43 and the inner collar portion 44 of one bobbin 4, and the outer collar portion 53 of the other bobbin 5 is wound. A second coil winding 7 is wound between the inner flange portions 54 (see FIG. 2). The terminal of the first coil winding 6 is connected to a predetermined terminal pin 9, and the terminal of the second coil winding 7 is connected to a predetermined terminal pin 9.

Further, an annular third magnetic core 3 is arranged between the inner flange portion 44 of one bobbin 4 and the inner flange portion 54 of the other bobbin 5. The third magnetic core 3 is sandwiched between the two bobbins 4 and 5, and most of the middle legs 11 and 21 of the first and second magnetic cores 1 and 2 are contained in the annulus. It is fitted and the gap G1 is arranged between the tip surfaces of the middle legs 11 and 21.

When assembling the first to third magnetic cores 1 to 3 and both bobbins 4 and 5, positioning fixing members 8 and 8 are arranged on both lower sides of both bobbins 4 and 5. As shown in FIGS. 8, 10 and 11, the positioning fixing members 8 and 8 have vertical pieces 82 and 82 extending upward in the center of the flat plate-shaped bases 81 and 81, and are inside the base 81. Slit-shaped engaging grooves 83, 83 are formed on both sides of the side.

Extensions 44a and 54a of the two inner flanges 44 and 54 of the bobbins 4 and 5 are engaged with the engaging grooves 83 and 83. Thereby, the axial positions of the inner flange portions 44 and 54 of the two bobbins 4 and 5 and the center positions thereof are defined.

Further, the vertical pieces 82, 82 are sandwiched between the tip surface of the outer leg portion 12 of the first magnetic core 1 and the tip surface of the outer leg portion 22 of the second magnetic core 2. The size of the dimension b of the gap gap G2 between the tip surfaces of the outer leg portions 12 and 22 of the first and second magnetic cores 1 and 2 is determined by the thickness of the vertical pieces 82 and 82 of the positioning fixing members 8 and 8. It is specified by the dimensions.

As shown in FIG. 10, the shapes of the vertical pieces 82 and 82 of the positioning and fixing members 8 and 8 are similar to the cross-sectional shapes of the outer leg portions 12 and 22, and are totally in contact with each other and are not biased. In addition, the vertical pieces 82 and 82 are formed with triangular openings 84 at the top and bottom, and are filled with an adhesive at the time of assembly, and are formed on the tip surfaces of the outer legs 12 and 22 of the first and second magnetic cores 1 and 2. It is fixed.

In this way, the positioning fixing members 8 and 8 and the third magnetic core 3 are combined between the first and second magnetic cores 1 and 2, so that they are wound around the bobbins 4 and 5. The gap G1 between the middle legs 11 and 21 can be accurately positioned at the intermediate position between the first and second coil windings 6 and 7, and in a 2-in-1 type magnetic coupling inductor, of each inductor It is possible to set the inductances equal to each other.

As a result, it is possible to eliminate the conventional inconvenience such that one of the inductors causes magnetic saturation due to the bias of the distance from each inductor to the magnetic gap.

Further, as shown in FIG. 9, the protrusions 44b and 54b formed at the lower ends of the inner flanges 44 and 54 of the two bobbins 4 and 5 are assembled by the tips of the protrusions 44b and 54b coming into contact with the substrate surface and the like. It functions to stabilize the posture during manufacturing in the process and the like.

As described above, the magnetic coupling inductor 100 of the embodiment has a third magnetic core 3 formed by an annular magnetic core between the first and second magnetic cores 1 and 2 and two bobbins 4 and 5 respectively assembled. It is configured to include a coupling inductor having a 2-in-1 (2in1) structure on the sandwich. Then, the magnetic fluxes passing through the third magnetic core 3 generated by the respective currents passing through the first coil winding 6 and the second coil winding 7 are in the same direction.

Specifically, as shown in FIG. 3, gaps G1 and G2 are formed between the first magnetic core 1 and the second magnetic core 2 between the middle legs 11 and 21 and the outer legs 12 and 22, respectively. Is separated. Therefore, in the first magnetic core 1, the magnetic fluxes passing through the connecting portions 13 and 13 from the outer leg portions 12 and 12 on both sides merge at the middle leg portion 11 and both toward the tip surface of the middle leg portion 11. Flows.

On the other hand, in the second magnetic core 2, the magnetic flux passing from the outer leg portions 22, 22 on both sides to the connecting portions 23, 23 merges at the middle leg portion 22, and both are on the tip surface of the middle leg portion 11. It flows toward. The magnetic fluxes flowing through these two middle leg portions 11 collide with each other at the tip surfaces of the middle leg portions 11, 21 and are separated into left and right, pass through the third magnetic core 3, and pass through the first and second magnetic cores 1, It reaches the outer legs 12 and 22 of 2.
As a result, magnetic loops L1 and L2 that circulate in the directions as shown in FIG. 3 are formed in the first and second magnetic cores 1 and 2 and the third magnetic core 3.

In the magnetic coupling inductor 100 of the above-described embodiment, as shown in FIG. 4, the thickness of the third magnetic core 3 is a, and the outer legs 12 of the first and second magnetic cores 1 and 2 are set. , When the gap amount of the gap G2 between 22 is b
a ≧ b (1)
It is configured so that the condition of is satisfied.

By configuring so that the above condition (1) is satisfied, the magnetic coupling inductor can be miniaturized.
That is, when a <b, the coupling coefficient, which is an important parameter of the coupling inductor, decreases. When the coupling coefficient decreases, a large current cannot be tolerated unless the coupling inductor is increased in size.
Therefore, it is preferable to reduce the size of the product by configuring it so as to satisfy the condition (1) in which a ≧ b.

Further, in the magnetic coupling inductor 100, as shown in FIG. 5, the thickness of the third magnetic core 3 is a, and the thickness of the connecting portions 13 and 23 of the first and second magnetic cores 1 and 2 is set. When c,
a ≧ c (2)
It is configured so that the condition of is satisfied.

By configuring so that the above condition (2) is satisfied, the magnetic coupling inductor can be miniaturized.
That is, when a <c, the normally circulating magnetic flux is not at the position related to c (positions of the connecting portions 13 and 23 of the first and second magnetic cores 1 and 2) but at positions related to a (first and first positions). Since it is saturated at the gap G1 position between the tip surfaces of the middle leg portions 11 and 21 of the magnetic cores 1 and 2 of 2, it becomes difficult to guarantee the function as a coupling inductor.

Further, when the duty (switching ON / OFF ratio) is set to a predetermined value, the magnetic fluxes flowing through the first and second magnetic cores 1 and 2 merge and flow into a (gap G1), and the third magnetism Since the core 3 is likely to be saturated, a is set to be c or more (the cross-sectional area of the third magnetic core 3 is equal to or larger than the cross-sectional areas of the connection portions 13 and 23) (output voltage). Vout / input voltage Vin ≥ 2).
Therefore, it is most preferable to configure the circuit so as to satisfy the condition (2) in which a = c to reduce the size of the product.
However, under the above condition (2), it has been confirmed that even if there is a tolerance of c (about ± 5%), the effect of reducing the size of the inductor is obtained. Therefore, the actual numerical range is as follows. The range in which the condition (2') is satisfied may be satisfied.
a ≧ 0.95c (2')

Further, in the magnetic coupling inductor 100, as shown in FIG. 6, the gap G1 between the middle leg portions 11 and 21 of the first and second magnetic cores 1 and 2 and the outer leg portions 12 and 22 on both sides are connected to each other. The sum of the gap amounts b of the two gaps G2 and G2 (basically 3b) and the gap amount between the inner peripheral surface of the annular core and the outer peripheral surfaces of the middle legs 11 and 21 in the third magnetic core 3 are f. Or, when the amount of gap between the outer peripheral surface of the annular core and the inner peripheral surfaces of the outer legs 12 and 22 in the third magnetic core 3 is g.
3b ≧ f (3)
or,
3b ≧ g (4)
It is configured so that the condition of is satisfied.

The magnetic coupling inductor can be miniaturized by configuring so that the above condition (3) or (4) is satisfied.
That is, when 3b <f and 3b <g, the coupling coefficient, which is an important parameter of the coupling inductor, decreases as in the case where the above condition (1) is not satisfied. When the coupling coefficient decreases, a large current cannot be tolerated unless the coupling inductor is increased in size.
Therefore, it is preferable to reduce the size of the product by configuring it so as to satisfy the condition (3) in which 3b ≧ f or the condition (4) in which 3b ≧ g is satisfied.

Although the fixing tape 10 is used for physically integrating the cores 1, 2, and 3 in the above embodiment, an adhesive, an adhesive tape, a tightening metal fitting, or the like may be used.

The current direction and coil winding direction flowing through the first coil winding 6 and the second coil winding 7 can be configured as follows, and if the following effects can be obtained. , Can be selected arbitrarily.
That is, when the two magnetic cores 1 and 2 are arranged so as to face each other as shown in FIG. 3, the outer legs 12 and 12 to the middle legs on both sides of the first magnetic core 1 by the first coil winding 6 are arranged. The magnetic flux passing through 11 and the magnetic flux passing through the middle leg portions 21 from the outer leg portions 22 and 22 on both sides of the second magnetic core 2 by the second coil winding 7 are formed between the tip surfaces of the middle leg portions 11 and 21. , It is a configuration formed so as to collide with each other in opposite directions.
As a result of such a configuration, in FIG. 3, the magnetic flux formed by the magnetic flux passing from the outer leg portions 12 and 12 on both sides of the first magnetic core 1 by the first coil winding 6 to the middle leg portion 11. The loop L1 and the magnetic flux loop L2 formed by the magnetic flux passing from the outer leg portions 22, 22 on both sides of the second magnetic core 2 by the second coil winding 7 to the middle leg portion 21, are the middle leg portions 11, 21. In this mode, the magnetic fluxes cancel each other out in opposite directions between the tip surfaces of the two, and a magnetic configuration (flow of magnetic flux) that can tolerate a large current is formed.

According to the present embodiment, the first magnetic coupling inductor portion is formed by the first coil winding 6 and the magnetic core portion around the first coil winding 6, and the second magnetic core portion is formed by the second coil winding 7 and the magnetic core portion around the second coil winding 7. The coupled inductors are configured in a state of being coupled to each other, and can have a magnetic configuration (flow of magnetic flux) that can tolerate a larger current than when the coupled inductors are composed of two independent inductors.

7a to 7c show another embodiment, and is an example in which a part of the outer circumference of the third magnetic core 31 is removed and the vertical dimension is reduced in the figure. That is, in the annular shape of the third magnetic core 31, the upper and lower bow-shaped portions that do not face the inner peripheral surfaces of the outer leg portions 12 and 22 of the first and second magnetic cores 1 and 2 are cut by the cut surface 3A. It has been removed (see FIGS. 7a and 7b).

In this case, the surface area of the arcuate surface 3B facing the arcuate inner surface of the outer leg portions 12 and 22 via the minute gap in the outer peripheral surface of the third magnetic core 31 is d, and the first or second magnetic force is used. When the surface area of the tip surfaces of the outer legs 12 and 22 of the cores 1 and 2 is e (see FIG. 7c),
d ≧ e (5)
It is preferable that the above conditions are satisfied.
By configuring so that the above condition (5) is satisfied, the magnetic coupling inductor can be miniaturized.

Since d of this condition (5) can be replaced with a of the above condition (2) and e of this condition (5) can be replaced with c of the above condition (2), d <e. As in the case where the above condition (2) and the like are not satisfied, the coupling coefficient, which is an important parameter of the coupling inductor, decreases.
That is, when the coupling coefficient decreases, a large current cannot be tolerated unless the coupling inductor is increased in size. Therefore, when d <e, it becomes difficult to reduce the size of the product.

Next, the manufacturing process of the magnetic coupling inductor 100 of the above embodiment will be described with reference to FIGS. 12a to 12e.

First, FIG. 12a shows the state of the finished product. When producing this, first, as shown in FIG. 12b, the second coil winding 7 is wound around the bobbin 5. Although not shown, the first coil winding 6 is similarly wound around the other bobbin 4. Then, the ends of the coil windings 6 and 7 are soldered and fixed to the predetermined terminal pins 9 of the terminal blocks 41 and 51, respectively.

Next, as shown in FIG. 12c, the positioning fixing members 8 and 8 are prepared, and the adhesive is filled and applied to each opening 84 of the vertical piece 82. Then, as shown in FIG. 12d, the bobbins 4 and 5 in which the coil windings 6 and 7 are wound are sandwiched between the two bobbins 4 and 5, and the third magnetic core 3 is sandwiched between the bobbins 4 and the bobbin 4. The end of the tubular portion 42 and the end of the other tubular portion 52 are assembled in a uniaxial shape so as to match the uneven shape (see FIG. 9).
At the same time, the positioning fixing members 8 and 8 are engaged on both sides, and the lower extension portions 44a and 55a of the inner flange portions 4 and 54 of the bobbin are engaged with the engaging grooves 83. The first magnetic core 1 and the second magnetic core 2 face each other at both ends, the middle legs 11 and 21 are inserted into the cylinders 42 and 52, respectively, and the outer legs 12 and 22 are bobbins 4 and 5. Assemble the bobbin so that it is located on the outer side (see FIGS. 8 and 9).

At that time, the positioning fixing members 8 and 8 are sandwiched between the tip surfaces of the outer legs 12 and 22 of both magnetic cores 1 and 2, and fixed with the adhesive previously applied. In FIG. 12d, the first magnetic core 1 is omitted.

Next, in a state where the first to third magnetic cores 1 to 3 are assembled to the bobbins 4 and 5 as described above, as shown in FIG. 12e, the fixing tape 10 is attached to the first and second magnetic cores 1. , 2 Fasten to the outer circumference and temporarily fix the whole. Further, on the bottom surface, an adhesive is applied to the contact portion P between the base 81 of the positioning fixing members 8 and 8 and the peripheral surface of the third magnetic core 3, and both are fixed and dried to complete the production. In this case, it is preferable to inspect the electrical characteristics before applying the adhesive.

Instead of the pair of PQ cores used in the above embodiment, an EE type core, an ER type core, and a pair of pot cores (those in which the outer leg portion surrounds the middle leg portion) and the like can also be used.
Further, various shapes can be adopted as the shape of the bobbin.

1 1st magnetic core 2 2nd magnetic core 3, 31 3rd magnetic core 4, 5 Bobbin 6 1st coil winding 7 2nd coil winding 8 Positioning fixing member 9 Terminal pin 10 Fixing tape 11 , 21 Middle leg 12,22 Outer leg 13,23 Connection 41,51 Terminal block 42,52 Cylinder 43,53 Outer flange 44,54 Inner flange 81 Base 82 Vertical piece 83 Engagement groove 100 Magnetic coupling Inductor G1, G2 gap

Claims (4)

A first magnetic core and a second magnetic core having a middle leg portion, an outer leg portion located on at least both sides of the middle leg portion, and a connecting portion connecting the middle leg portion and the outer leg portion, respectively. When,
A bobbin through which the first magnetic core and the middle leg portion of the second magnetic core are inserted and arranged on the outside of each of the middle leg portions,
A first coil winding and a second coil winding wound around each of the bobbins,
It is provided with an annular third magnetic core into which the middle leg is fitted while being sandwiched between the two bobbins.
In the first and second magnetic cores, the corresponding legs are abutted against each other, and a gap is provided between each of the corresponding legs.
The magnetic fluxes passing through the third magnetic core generated by the respective currents passing through the first coil winding and the second coil winding are oriented in the same direction.
When the thickness of the third magnetic core is a and the gap amount between the outer legs of the first and second magnetic cores is b.
a ≧ b (1)
A magnetically coupled inductor characterized in that the above conditions are satisfied. When the thickness of the third magnetic core is a and the thickness of the connection portion of the first and second magnetic cores is c,
a ≧ c (2)
The magnetic coupling inductor according to claim 1, wherein the conditions of the above are satisfied. The magnetic according to claim 1 or 2, further comprising a positioning fixing member for fixing the intermediate portion in the thickness direction of the third magnetic core at an intermediate position between the tip surfaces of the two middle leg portions. Coupled inductor. In the positioning fixing member, a vertical piece extending upward is erected in the center of a flat plate-shaped base portion, slit-shaped engaging grooves are formed on both sides of the inner side of the base portion, and the bobbin is formed in the engaging groove. The magnetic coupling inductor according to claim 3, wherein the extension portions of the two inner flange portions of the above are configured to be engaged with each other.

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