JP7373119B2 - magnetically coupled inductor - Google Patents

Description

The present invention relates to a magnetically coupled inductor configured to include a 2-in-1 coupled inductor with an annular core sandwiched between a pair of PQ cores (including an E core, etc.).

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

Patent No. 5062439 Special Publication No. 4-14487

However, in the aspects of these patent documents, depending on the configuration of the combination of a pair of PQ cores and a magnetic core sandwiched between them, the cross-sectional area of the core becomes large in order to pass the combined magnetic flux, resulting in a magnetically coupled inductor. There is a risk that the size of the device will increase and that miniaturization will not be achieved sufficiently.

The present invention has been made in view of the above circumstances, and has a 2-in-1 structure that essentially functions as two independent magnetically coupled inductors, and aims to optimize the arrangement conditions related to the combination of each core. Accordingly, it is an object of the present invention to provide a magnetically coupled inductor whose external dimensions can be further reduced.

In order to solve the above problems, the magnetically coupled inductor of the present invention has the following features:
A first magnetic core and a second magnetic core each having a middle leg part, an outer leg part located on at least both sides of the middle leg part, and a connecting part connecting the middle leg part and the outer leg part. and,
a bobbin through which the middle leg portions of the first magnetic core and 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;
a third annular magnetic core into which the middle leg is inserted while being held between the two bobbins;
In the first and second magnetic cores, corresponding leg portions are butted against each other, and a gap is provided between each of the corresponding leg portions,
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 in the same direction,
When the thickness of the third magnetic core is a, and the amount of gap 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 following conditions are satisfied.

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

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

Further, in the positioning and fixing member, a vertical piece extending upward is provided at the center of a flat base, and a slit-shaped engagement groove is formed on both sides of the inner side of the base. Preferably, the extensions of the two inner flanges of the bobbin are configured to be engaged with each other.

According to the magnetically coupled inductor according to the present invention, it is possible to realize a 2-in-1 structure that substantially functions as two independent magnetically coupled inductors while reducing the external dimensions of a magnetic core assembly consisting of a combination of multiple cores. Is possible. In addition, by optimizing the arrangement conditions related to the combination of each core, the external dimensions can be further reduced, and the mounting space can also be reduced.

FIG. 1 is an overall perspective view of a magnetically coupled inductor according to a first embodiment of the present invention. FIG. 2 is an exploded perspective view of FIG. 1 excluding the tape. It is a sectional view of a core part for explaining a magnetic loop. FIG. 3 is a partial plan view illustrating the arrangement conditions of the core structure. FIG. 7 is a partial plan view illustrating other arrangement conditions of the core structure. FIG. 3 is a cross-sectional view for explaining the dimensional relationship of the core structure of the first embodiment. FIG. 7 is a front view of a core portion showing another embodiment. Figure 7a is a perspective view of Figure 7a; FIG. 7a is a perspective view with one PQ core removed from FIG. 7a; FIG. 3 is a perspective view showing a combination of two bobbins and a positioning and fixing member. It is a perspective view showing the combination structure of two bobbins. FIG. 3 is a perspective view showing a combined structure of one PQ core and a positioning and fixing member. FIG. 3 is a central cross-sectional front view of the main part. FIG. 2 is an overall perspective view of a magnetically coupled inductor viewed 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 adhesion process.

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

The magnetically coupled inductor 100 of this embodiment includes first and second magnetic cores 1 and 2 made of PQ cores, a third magnetic core 3 made of an annular core (ring core), two bobbins 4 and 5, and a first It also includes second coil windings 6, 7, two positioning and fixing members 8, 8, eight terminal pins 9 on both sides, and a fixing tape 10 wrapped around the outer periphery.

A pair of PQ cores, the first magnetic core 1 and the second magnetic core 2, are made of, for example, ferrite cores, have the same external dimensions, and are located on the middle legs 11, 21 and on both sides of the middle legs 11, 21. It has outer leg parts 12, 22 and flat connecting parts 13, 23 that connect the middle leg parts 11, 21 and the outer leg parts 12, 22, respectively, and the first and second magnetic cores 1, 2 are arranged facing each other.

The middle legs 11, 21 have a cylindrical shape, and the length is approximately 1/2 of the distance between the opposing connecting parts 13, 23, and the outer legs 12, 22 have an arcuate inner surface and an arcuate 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 (disc-like) shape with a rectangular cross section.

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

Cylindrical portions 42 and 52 are arranged above the terminal blocks 41 and 51 to extend in the axial direction. A disk-shaped outer flange portion 43, 53 is provided at one end of the cylindrical portion 42, 52 on the terminal block 41, 51 side, and a disk-shaped inner flange portion 44, 54 is provided at the opposite end. Positioning regulating members 8, 8, which will be described later, are engaged with downwardly extending extensions 44a, 54a of the inner flanges 44, 54, and protrusions 44b, 54b are formed at the lower ends (see FIG. 9). . Further, butterfly-shaped projections 45, 55 are provided at the upper and lower ends of the outer flanges 43, 53 of the bobbins 4, 5, and the upper and lower inclined surfaces of the connecting parts 13, 23 of the first and second magnetic cores 1, 2 are provided. It is configured to come into contact with.

In this way, by providing the butterfly-shaped protrusions 45, 55 at the upper and lower ends of the outer flanges 43, 53 of the bobbins 4, 5, the first and second coil windings 6, 7 (including the lead wires ) and the first and second magnetic cores 1, 2 are improved, and each magnetic core 1, 2, 3 and each bobbin 4, 5 can be stably fixed to each other.

The ends of the cylindrical parts 42, 52 of the bobbins 4, 5 are provided in a symmetrical uneven shape for engagement, and the concave part 42b of one bobbin 4 engages the convex part 52a (see FIG. 8) of the other bobbin 5. , the axes of both cylindrical portions 42 and 52 are made to coincide with each other.

The middle leg part 11 of the first magnetic core 1 is connected to the continuous cylindrical parts 42 and 52 of the bobbins 4 and 5 from one end, and the middle leg part 21 of the second magnetic core 2 is connected to the continuous cylindrical parts 42 and 52 of the bobbins 4 and 5 from the other end. By being inserted through each, the bobbins 4 and 5 are arranged on the outside of each of the middle leg parts 11 and 21.

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 butted against each other, and each of the corresponding legs is Gaps G1 and G2 are provided between them (see FIG. 3), and the size b (basically the same size) of these gaps G1 and G2 is defined by a positioning and fixing member 8 (so-called spacer), which will be described later.

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

Furthermore, an annular third magnetic core 3 is disposed between the inner flange 44 of one bobbin 4 and the inner flange 54 of the other bobbin 5. The third magnetic core 3 is held 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 located within the ring. The gap G1 is disposed between the distal end 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 and fixing members 8 and 8 are disposed on both sides of the lower portions of both bobbins 4 and 5. As shown in FIGS. 8, 10, and 11, the positioning and fixing members 8, 8 are provided with vertical pieces 82, 82 that extend upwardly at the center of the flat bases 81, 81, and the inside of the base 81. Slit-shaped engagement grooves 83, 83 are formed on both sides of the sides.

Extension portions 44a and 54a of the two inner flanges 44 and 54 of the bobbins 4 and 5 are engaged with the engagement grooves 83 and 83, respectively. Thereby, the axial positions of the inner flanges 44, 54 of the two bobbins 4, 5 and their center positions are defined.

Further, the vertical pieces 82, 82 are sandwiched between the distal end surface of the outer leg portion 12 of the first magnetic core 1 and the distal end surface of the outer leg portion 22 of the second magnetic core 2. The size b of the clearance 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 and fixing members 8 and 8. It is defined by dimensions.

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

In this way, by combining the positioning and fixing members 8, 8 and the third magnetic core 3 between the first and second magnetic cores 1, 2, winding on each bobbin 4, 5 is possible. The gap G1 between the middle leg portions 11 and 21 can be accurately positioned at the intermediate position between the first and second coil windings 6 and 7. It is possible to set the inductances equal to each other.

This makes it possible to eliminate the conventional disadvantages such as magnetic saturation occurring in one of the inductors due to uneven distances 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 touching the substrate surface etc. with their tips. It functions to stabilize the posture during manufacturing process etc.

As described above, the magnetically coupled inductor 100 of the embodiment has the third magnetic core 3 formed by the annular magnetic core between the two bobbins 4 and 5 assembled with the first and second magnetic cores 1 and 2, respectively. It has a configuration in which a coupled inductor of a 2-in-1 (2-in-1) structure is provided on both sides. 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 middle legs 11 and 21 and the outer legs 12 and 22 of the first magnetic core 1 and the second magnetic core 2, respectively. separated. Therefore, in the first magnetic core 1, the magnetic fluxes passing through the connecting parts 13, 13 from the outer legs 12, 12 on both sides merge at the middle leg 11, and both flow toward the distal end surface of the middle leg 11. It flows.

On the other hand, in the second magnetic core 2, the magnetic fluxes passing through the connecting parts 23, 23 from the outer legs 22, 22 on both sides merge at the middle leg 22, and both reach the tip surface of the middle leg 11. flowing towards. The magnetic fluxes flowing through these two middle leg parts 11 collide with each other at the tip surfaces of the middle leg parts 11 and 21, are divided into left and right sides, pass through the third magnetic core 3, and then pass through the first and second magnetic cores 1, The outer legs 12 and 22 of No. 2 are reached.
As a result, magnetic loops L1 and L2 circulating in the directions as shown in FIG. 3 are formed in each of the first and second magnetic cores 1 and 2 and the third magnetic core 3.

In the magnetically coupled inductor 100 of the embodiment described above, as shown in FIG. , 22, when the gap amount of the gap G2 between them is b,
a≧b (1)
The system is configured so that the following conditions are satisfied.

By configuring the magnetically coupled inductor so that the above condition (1) is satisfied, it is possible to downsize the magnetically coupled inductor.
That is, when a<b, the coupling coefficient, which is an important parameter of the coupled inductor, decreases. If the coupling coefficient decreases, a large current cannot be tolerated unless the coupled inductor is made larger.
Therefore, it is preferable to reduce the size of the product by configuring it to satisfy the condition (1) that a≧b.

Further, in the magnetically coupled inductor 100, as shown in FIG. When c,
a≧c (2)
The system is configured so that the following conditions are satisfied.

By configuring the magnetically coupled inductor so that the above condition (2) is satisfied, it is possible to downsize the magnetically coupled inductor.
In other words, when a<c, the normally circulating magnetic flux is not located at the position associated with c (the position of the connecting portions 13 and 23 of the first and second magnetic cores 1 and 2), but is located at the position associated with a (the first and second magnetic cores 1 and 2). Since the gap G1 between the end surfaces of the middle leg portions 11 and 21 of the magnetic cores 1 and 2 of 2 is saturated, it becomes difficult to ensure the function as a coupled inductor.

Furthermore, 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 magnetic Since the core 3 is likely to be saturated, a is set to be greater than or equal to c (the cross-sectional area of the third magnetic core 3 is greater than or equal to the cross-sectional area of the connecting portions 13 and 23). Vout/input voltage Vin≧2).
Therefore, it is most preferable to configure the circuit so as to satisfy the condition (2) that a=c to reduce the size of the product.
However, under condition (2) above, it has been confirmed that even if there is a tolerance of c (approximately ±5%), the effect of miniaturizing the inductor can be achieved, so the actual numerical range is as follows. There is no problem as a range in which condition (2') is satisfied.
a≧0.95c (2')

Furthermore, in the magnetically coupled inductor 100, as shown in FIG. The sum of the gap amounts b of the two gaps G2 and G2 (basically 3b) and the gap amount between the inner circumferential surface of the annular core and the outer circumferential surface of the middle leg portions 11 and 21 in the third magnetic core 3 are f. Or, when the amount of gap between the outer circumferential surface of the annular core in the third magnetic core 3 and the inner circumferential surface of the outer leg portions 12 and 22 is g,
3b≧f (3)
or
3b≧g (4)
The system is configured so that the following conditions are satisfied.

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

Although the cores 1, 2, and 3 are physically integrated using the fixing tape 10 in the embodiment described above, adhesives, adhesive tapes, fastening metal fittings, etc. may also be used.

If the current direction flowing through the first coil winding 6 and the second coil winding 7 and the coil winding direction can be configured as shown below, and the following effects can be achieved, then , can be arbitrarily selected.
That is, when the two magnetic cores 1 and 2 are arranged to face each other as shown in FIG. 11 and the magnetic flux passing from the outer legs 22, 22 on both sides of the second magnetic core 2 formed by the second coil winding 7 to the middle leg 21 between the tip surfaces of the middle legs 11, 21. , are formed so that they collide in opposite directions.
As a result of such a configuration, as shown in FIG. The loop L1 and the magnetic flux loop L2 formed by the magnetic flux passing through the middle leg part 21 from the outer leg parts 22, 22 on both sides of the second magnetic core 2 by the second coil winding 7 are connected to the middle leg part 11, 21. This mode has the effect of forming a magnetic configuration (flow of magnetic flux) that can tolerate a large current by forming a relationship between the tip surfaces of the magnetic fluxes in opposite directions and canceling each other out.

According to the present embodiment, the first magnetic coupling inductor section is formed by the first coil winding 6 and the magnetic core portion around it, and the second magnetic coupling inductor section is formed by the second coil winding 7 and the magnetic core portion around it. Since the coupled inductor sections are configured in a state where they are coupled to each other, a magnetic configuration (flow of magnetic flux) that can tolerate a larger current than when configured with two independent inductors can be achieved.

FIGS. 7a to 7c show another embodiment, in which a part of the outer periphery of the third magnetic core 31 is removed to reduce the size in the vertical direction in the figures. That is, in the annular shape of the third magnetic core 31, the upper and lower arcuate 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. (see Figures 7a and 7b).

In this case, the surface area of the arcuate surface 3B facing the arcuate inner surface of the outer legs 12, 22 through a minute gap on the outer circumferential surface of the third magnetic core 31 is d, and the first or second magnetic 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 configuration is such that the following conditions are satisfied.
By configuring the magnetically coupled inductor so that the above condition (5) is satisfied, it is possible to downsize the magnetically coupled inductor.

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

Next, the manufacturing process of the magnetically coupled inductor 100 of the above embodiment will be explained with reference to FIGS. 12a to 12e.

First, FIG. 12a shows 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 predetermined terminal pins 9 of the terminal blocks 41 and 51, respectively.

Next, as shown in FIG. 12c, the positioning and fixing members 8, 8 are prepared, and each opening 84 of the vertical piece 82 is filled with an adhesive. Then, as shown in FIG. 12d, the bobbins 4 and 5 on which the coil windings 6 and 7 are respectively wound are placed, while the third magnetic core 3 is held between both bobbins 4 and 5. The end of the cylindrical portion 42 and the end of the other cylindrical portion 52 are assembled uniaxially so that the concave and convex shapes match (see FIG. 9).
At the same time, the positioning fixing members 8, 8 are engaged on both sides, the lower extensions 44a, 55a of the inner flanges 4, 54 of the bobbin are engaged with the engagement grooves 83, and the assembled bobbins 4, 5 are The middle legs 11 and 21 are inserted into the cylindrical parts 42 and 52, respectively, with the first magnetic core 1 and the second magnetic core 2 facing each other at both ends, and the outer legs 12 and 22 are inserted into the bobbins 4 and 5. (See Figures 8 and 9).

At this time, the positioning and fixing members 8, 8 are held between the distal end surfaces of the outer leg parts 12, 22 of both magnetic cores 1, 2, and fixed with the adhesive previously applied. Note that the first magnetic core 1 is omitted in FIG. 12d.

Next, with the first to third magnetic cores 1 to 3 assembled to the bobbins 4 and 5 as described above, the fixing tape 10 is attached to the first and second magnetic cores 1 as shown in FIG. 12e. , 2 to temporarily fix the whole. Furthermore, on the bottom surface, adhesive is applied to the contact portion P between the base 81 of the positioning and fixing members 8, 8 and the circumferential surface of the third magnetic core 3 to fix both, and then drying to complete the production. In this case, it is preferable to test the electrical characteristics before applying the adhesive.

Instead of the pair of PQ cores used in the above embodiments, an EE type core, an EER type core, or even a pair of pot cores (in which the outer leg surrounds the middle leg) can also be used.
Moreover, various shapes can be adopted as the shape of the bobbin.

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

Claims (4)

A first magnetic core and a second magnetic core each having a middle leg part, an outer leg part located on at least both sides of the middle leg part, and a connecting part connecting the middle leg part and the outer leg part. and,
a bobbin through which the middle leg portions of the first magnetic core and 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;
a third annular magnetic core into which the middle leg is inserted while being held between the two bobbins;
In the first and second magnetic cores, corresponding leg portions are butted against each other, and a gap is provided between each of the corresponding leg portions,
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 in the same direction,
When the thickness of the third magnetic core is a, and the amount of gap between the outer legs of the first and second magnetic cores is b,
a≧b (1)
A magnetically coupled inductor characterized in that it is configured so that the following conditions are satisfied. When the thickness of the third magnetic core is a, and the thickness of the connecting portion of the first and second magnetic cores is c,
a≧c (2)
2. The magnetically coupled inductor according to claim 1, wherein the magnetically coupled inductor is configured such that the following conditions are satisfied. The magnetism according to claim 1 or 2, further comprising a positioning and fixing member that fixes the thicknesswise intermediate portion of the third magnetic core at an intermediate position between the tip surfaces of the two middle leg portions. coupled inductor. The positioning and fixing member has a vertical piece extending upwardly in the center of a flat base, and a slit-shaped engagement groove is formed on both sides of the inner side of the base, and the bobbin is inserted into the engagement groove. 4. The magnetically coupled inductor according to claim 3, wherein the extensions of the two inner flanges are configured to be engaged with each other.

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