JPH0845743A - Inductor - Google Patents

Abstract

PURPOSE:To obtain a high-inductance inductor, which is thin, small-sized and suitable for a booster circuit or the like. CONSTITUTION:A main core 11 and coupled cores 12 and 13 are formed of a laminated material consisting of an iron material and can be also subjected to punching by a press process. The main core 11 and the cores 12 and 13 are vertically superposed, are surface-made contact with each other and a magnetic circuit from the core 11 to go through the cores 12 and 13 is formed. Gap materials 14 and 15, such as polyimide films, are interposed between the surface-making contact parts of the core 11 with the cores 12 and 13 and the cores 12 and 13 and gaps (g) for avoiding a magnetic saturation are respectively formed between the core 11 and the cores 12 and 13. As the core 11 surface- makes contact with the cores 12 and 13 and the interval between the gaps is formed of the sheet or film-shaped gap materials 14 and 15, a setting of the distance between the gaps and an adjustment of the distance between the gaps are easy. Moreover, it is possible to set an inductor in a high inductance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact and high-inductance inductor suitable for a booster circuit or the like.

[0002]

2. Description of the Related Art FIG. 10 (A) is a perspective view showing an inductor used in various conventional circuits, and FIG. 10 (B) is a longitudinal sectional view thereof. In this inductor, a winding 2 is provided on a drum-shaped core 1 made of ferrite. The core 1 has flange portions 1a and 1b on the lower and upper portions, and the core 1 is housed in a cylindrical pot 3. Like the core 1, the pot 3 is made of ferrite. In this inductor, when a current is applied to the winding 2, a magnetic path that goes from the core 1 to the pot 3 is formed. Further, in this type of inductor, a gap g of a nonmagnetic region is formed between the periphery of the lower flange 1a of the core 1 and the inner peripheral surface of the opening (lower end) of the pot 3. By providing this gap g, magnetic saturation in the magnetic path is avoided and the saturation magnetic field is increased.

[0003]

However, the conventional inductor shown in FIG. 10 has the following problems. (1) Since it is a tall structure and it is difficult to make it thin, it is difficult to use it in the circuit of thin products. (2) Since the shape of the core 1 and the pot 2 is complicated and these members are made of ferrite, the workability is poor and the cost is high. (3) Since the magnetic saturation is influenced by the gap g, it is necessary to adjust the gap g during manufacturing. However, the gap g is formed in a cylindrical shape around the flange 1a of the core 1. Therefore, it is difficult to set and adjust the gap g.

The present invention solves the above-mentioned conventional problems, and an object thereof is to provide an inductor which is thin, has good workability, is easy to adjust the gap, and can obtain a high inductance.

[0005]

According to the present invention, there is provided a main core provided with a winding wire and a connecting core provided between end portions of the main core. Are superposed and are in surface contact with each other.

The connecting cores can be provided so as to overlap only one surface of the main core, but it is preferable to provide a pair of the connecting cores with the main core interposed therebetween.

The planar shape of the main core is, for example, L-shaped or U-shaped.

Further, it is preferable that the main core and the connecting core are formed of a laminated body of an iron-based material. In this case, the surface layers of the main core and the connecting core are in surface contact with each other.

In the above, it is preferable that a non-magnetic gap material is interposed between the main core and the connecting core. This gap material is, for example, a resin film or resin sheet such as polyimide.

Further, when a pair of connecting cores are provided on both sides of the main core, an extension portion is integrally provided on a collar portion that regulates both ends of the winding, and both connecting cores are provided at a portion where the main core is absent. It is possible to have a structure in which the extension portion is interposed between the connecting cores to maintain the distance between the connecting cores.

[0011]

In the above means, the main core has, for example, a rectangular cross section and a shape that spreads in a plane, for example, an L-shape or a U-shape, and the winding is provided on the main core. A connecting core is provided between both ends of the main core, and the connecting core is superposed on the end of the main core to be in surface contact with each other, and the surface contact portion serves as a gap for avoiding magnetic saturation. Since the main core has a structure that expands in a plane, the entire structure can be made thin.
Further, in the case where the main core and the connecting core, or at least the main core is a laminated body of an iron-based material, it is also possible to punch the L-shaped or U-shaped planar shape by pressing. It has excellent mass productivity and can be manufactured at low cost.

Connection cores are stacked on both ends of the main core,
For example, the surface layers of a stack of iron-based materials are overlapped and are in surface contact, and a gap is formed in this surface contact portion to avoid magnetic saturation of the magnetic path passing through the main core and the connecting core. ing. Since the main core and the connecting core are overlapped and are in surface contact with each other, the contact state between the main core and the connecting core is stable, so that the gap can be easily formed, and the contact between the main core and the connecting core is easy. It is easy to adjust the area and the gap between the main core and the connecting core. In particular, if a gap member made of a film or sheet of a non-magnetic material is interposed between the surface contact portions of the main core and the connecting core, the gap between the gaps can be set freely depending on the thickness of the film or sheet. In other words, the main core and the connecting core are brought into surface contact with each other, and a film-like or sheet-like gap material is interposed in this surface contact portion, whereby the gap can be set very easily, or individual products can be set. The size of the gap can be standardized, the variation in the size of the gap between products can be eliminated, and the magnetic characteristics can be standardized.

If a pair of connecting cores are provided and a gap is formed between the main core and each connecting core, it is easy to set the magnetic characteristics by adjusting the gaps. For example, one gap is fixed and the other is fixed. By adjusting the gap of, it becomes easier to adjust the magnetic characteristics of the inductor.

Further, when a pair of connecting cores is used, an extension portion of the collar portion for controlling the end portion of the winding provided on the main core is interposed between the connecting cores, so that the connecting cores are connected to each other. The distance can be kept constant, and the support of the connecting core is stable.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a perspective view showing an inductor according to a first embodiment of the present invention, and FIG. 2 is an exploded perspective view thereof. The cross section of the main core 11 has a rectangular shape with a thickness t1 and a width dimension w1. The planar shape of the main core 11 is L-shaped. The dimension of the long side of the L-shape is indicated by A, and the dimension of the short side is indicated by B. The main core 11 is a laminated body in which iron-based materials are laminated in the t1 direction. By forming the iron-based material as a laminated body, deterioration of magnetic characteristics due to eddy current loss and the like is prevented. The thickness of one layer of iron-based material is 12 ~
It is about 25 μm. Permalloy (F
e-Ni-based alloy), Fe-Si-B-based amorphous material, or Fe-M-B-based microcrystalline alloy (where M is
Metals such as Zr and Nb) having an average crystal grain size of 20 nm or less are preferably used.

The thickness t1 of the main core 11 is, for example, 0.5 m.
m, the width dimension w1 is, for example, 0.5 mm, the long side dimension A is, for example, 6 to 4 mm, and the short side dimension B is, for example, about 4 to 2 mm. As described above, the main core 11 has a shape that extends in an L shape in a plan view and has a thickness t1 of about 0.5 mm. Therefore, it is possible to perform punching and molding from a plate material at low cost. Mass production is possible. Main core 11
The lower connecting core 12 is provided on the lower side, and the upper connecting core 13 is provided on the upper side. Each connecting core 12 and 13
Is a laminated body of the same iron-based material as the main core 11, and for example, permalloy (Fe) having a thickness of 12 to 25 μm.
-Ni-based alloy), Fe-Si-B-based amorphous material, or Fe-M-B-based microcrystalline alloy (where M is
Metals such as Zr and Nb) having an average crystal grain size of 20 nm or less are preferably used. Each connecting core 12 and 13
Is a rectangular cross-section having a thickness t2 of 0.25 mm and a width dimension w1 of 0.5 mm, for example.
It is possible to perform punching and forming by pressing similarly to.

The connecting cores 12 and 13 extend in a plane and have the same L shape as the main core 11. The long side dimension A of the L shape is, for example, 6 to 4 mm, and the short side dimension B is, for example, about 4 to 2 mm. The connecting cores 12 and 13 connect the both ends of the main core 11. The lower surface (A) of both ends of the main core 11, that is, the surface layer portion on the lower surface side of the laminated body of the main core 11 is a flat surface, and the upper surfaces (B) of both ends of the lower coupling core 12, that is, the laminated body of the coupling core 12. The surface layer portion on the upper surface side is also a flat surface, and the upper surface (b) is superposed on the lower surface (a) so that they are in surface contact with each other. Similarly, the upper surfaces (C) of both ends of the main core 11 are also planar, and the lower surfaces (D) of both ends of the upper coupling core 13 are also flat, and the lower surfaces (D) are superposed on the upper surface (C). They are in surface contact.

The lower surfaces (A) of both ends of the main core 11 and the upper surfaces (B) of both ends of the connecting core 12 are brought into surface contact with each other, and the upper surfaces (C) of both ends of the main core 11 are connected. Core 13
By the surface contact with the lower surface (d) of both end portions of G, a gap g is formed between the main core 11 and each of the connecting cores 12 and 13. In order to set the gap (gap length) of the gap g, the gap material 1 is provided between the main core 11 and the connecting core 12.
4 is interposed as necessary, and the main core 11 and the connecting core 13
The gap material 15 is interposed between the and. The gap members 14 and 15 are sheets or films of a non-magnetic material, and in the embodiment, polyimide films are used as the gap members 14 and 15. Gap material 14
And 15 are selected from different thicknesses and used,
The thickness is, for example, 12.5 μm, 25 μm, 50 μm or the like. Then, the L-shaped long side portion 11 of the main core 11
A winding 16 is provided on a. The winding is a coated copper wire or a coated conductive wire such as soft iron. For example, a soft iron coated conductive wire having a diameter of 50 μm wound about 500 turns is used.

The inductor shown in FIG. 1 is a thin type having an overall thickness T of about 1 mm, and has a small planar shape with a maximum size A × B of about 6 × 4 mm. Therefore, it is suitable for a thin and small product, for example, a step-up chopper circuit for driving electroluminescence of a wristwatch. The path (magnetic path) of the magnetic flux generated when the winding 16 is energized is such that the main core 11 and the upper and lower connecting cores 12,
The route is to return to the main core 11 via 13
And the upper and lower connecting cores 12 and 13 are in contact with each other with a gap g.
Is formed, magnetic saturation in the magnetic path is avoided and the saturation magnetic field is increased.

The main core 11 and the connecting cores 12 and 13 are
High inductance can be obtained by forming a material having a high magnetic permeability such as permalloy, and properly providing the gap g to avoid magnetic saturation.
= 6 mm, B = 4 mm, and the number of windings of the winding 16 is 500, the inductance can be increased to about 10 mH. As described above, this inductor is provided in, for example, a boost chopper circuit for driving electroluminescence. An AC voltage of about 100V is required in the electroluminescence drive circuit, but an AC electromotive force of about 100V can be induced in the inductor of the above embodiment. The voltage generated by this electromotive force is different when the connecting core is provided only on one side of the main core 11 and when the connecting cores 12 and 13 are provided on both sides of the main core 11, and in each case, the gap The gap (gap length) of g is adjusted by adjusting the thickness of the gap material 14 or 15.

Tables 1 and 2 below show the results of examining the generated voltage that can be induced by the inductor shown in FIG. The main core 11 and the connecting cores 12 and 13 of the inductor are formed by a laminated body of permalloy having a thickness of 12 μm, and the dimensions are t1 = 0.5 mm, t2 = 0.25 mm, w1 = 0.5.
mm, A = 6 mm, and B = 4 mm. The winding 16 is made of soft iron coated wire with a diameter of 50 μm and the number of turns is 500.
It was a turn. The values shown in Table 1 and Table 2 are obtained by applying an alternating current under the same conditions to the winding 16 and measuring the maximum value of the induced voltage. First, the connecting cores 12 and 13
The highest voltage in Table 1 shows the generated voltage obtained in the state where both ends of the main core 11 are not connected without being provided. The generated voltage at this time is 87.2 to 88.8V. The second column to the bottom column of Table 1 show the generated voltage when only one connecting core is provided. The gap length “0” means the main cores 11 and 1
The case where the gap material 14 is not interposed between the individual connecting cores 12 is shown, and the gap lengths of "12.5", "25", and "5" are shown.
0 ”has a thickness of 12.5 μm, 25 μm, and 50, respectively.
The case where the gap material 14 of μm is interposed is shown.
The maximum voltage is generated when the gap material is not interposed, and the maximum value is 96.8V.

[0022]

[Table 1]

Next, Table 2 shows the voltage induced when the connecting cores 12 and 13 are provided on both upper and lower sides of the main core 11. The measurement is made when the gap material 14 is not interposed between the one connecting core 12 and the main core 11 (gap length (1)
Is “0”), and a gap material 14 having a thickness of 12.5 μm is interposed between the one connecting core 12 and the main core 11 (gap length (1) is “12.5”), one connecting A gap member 1 having a thickness of 25 μm between the core 12 and the main core 11
4 was carried out (gap length (1) was "25"). In each of these cases,
The gap material 1 is provided between the other connecting core 13 and the main core 11.
When 5 is not inserted (gap length (2) is “0”),
When the gap material 15 having a thickness of 12.5 μm is interposed (gap length (2) is “12.5”), when the gap material 15 having a thickness of 25 μm is interposed (gap length (2) is “25”) ), And the gap material 15 having a thickness of 50 μm was interposed (the gap length (2) was “50”), the maximum value of the induced voltage was measured.

[0024]

[Table 2]

Comparing Table 1 and Table 2, first, Table 1
From the case where no connecting core is provided in the main core 11
It can be seen that the generated voltage is higher when one connection core is provided. Further, it can be seen from Table 2 that the generated voltage is further increased by providing the pair of connecting cores 12 and 13 on both sides of the main core 11.

In Table 1, it can be seen that when only one of the connecting cores is provided, the generated voltage varies depending on the gap g, and the generated voltage becomes the highest when the gap material is not provided. Also in Table 2, it can be seen that when the connecting cores 12 and 13 are provided on both sides of the main core 11, the generated voltage varies due to the change in the gap g on both sides of the main core 11. In Table 2, the generated voltage is high when the gap material is not provided in one of the gaps (leftmost column) and when the gap material having a thickness of 12.5 μm is interposed in the one gap (middle column). It turns out that it exceeds 100V. Further, in the leftmost column and the middle column of Table 2, adjustment of the generated voltage (adjustment of inductance) is made to some extent by fixing the gap interval on one side to 0 or 12.5 μm and changing the thickness of the gap material on the other side. It has been shown that it can be done in a wide range. In Tables 1 and 2, the fact that the gap length is described as "0" does not mean that the gap at the surface contact portion between the main core and the connecting core is completely eliminated, and Without interposing gap material,
This means that the minimum gap distance (gap length) results from the roughness of the surface of the main core and the connecting core.

From the above, it can be seen that by providing one or more connecting cores connecting both ends of the main core 11, a high inductance can be obtained and the voltage generated by self-induction becomes high, and further, both sides of the main core 11 can be obtained. Connecting cores 12 and 13
It can be seen that by providing the, the higher voltage can be obtained and the generated voltage can be increased. Moreover, when the connecting cores 12 and 13 are provided on both sides of the main core 11, the gap between one connecting core and the main core 11 is fixed and the other connecting core and the main core 11 are fixed. By changing the thickness of the gap material between them, it becomes possible to adjust the voltage generated by the inductance and self-induction in a wide range to some extent. When fixing the gap between one of the connecting cores and the main core 11, it is preferable not to insert a gap material between the main core 11 and the connecting core or to insert a gap material of about 12.5 μm. .

FIG. 3 is a perspective view showing a second embodiment of the inductor of the present invention, and FIG. 4 is a perspective view showing a main core used in this inductor. The inductor shown in FIG. 3 has the same structure as that shown in FIG.
2 and 13, gap members 14 and 15, and windings 16, and the materials and dimensions of these components are the same as those of the embodiment shown in FIGS. 1 and 2. However, this second
In the embodiment, as shown in FIG. 4, a pair of flange members 17 and 18 are fitted to the long side portion 11a of the main core 11 with a space therebetween. Each of the collar members 17 and 18 has a main core 1
Rectangular holes 17a and 18a corresponding to the cross section of 1 are formed,
In addition, the notch 17 continuous with the rectangular holes 17a and 18a
b, 18b are formed. The collar members 17 and 18 are made of a non-magnetic material having a little elasticity, and the notches 17b and 18b are passed through the long side portion 11a so that the collar members 17 and 18 are attached to the main core 11. It can be fitted.

The collar members 17 and 18 are fitted to the main core 11 in a step before the winding 16 is formed. Then, a wire is wound between the collar members 17 and 18 to form the winding 16. By providing the one brim member 17, it is possible to prevent the wire rod being wound around the corner (e) of the main core 11 from being damaged or cut. Further, by providing the other brim member 18, it is possible to prevent the winding 16 from collapsing. Further, the collar members 17 and 18 are the long side portions 11 a of the main core 11.
Since it can be attached by fitting it on, assembly work is also easy.

FIG. 5 is a perspective view of an inductor according to a third embodiment of the present invention, and FIG. 6 is an exploded perspective view thereof. The main core 11, the connecting cores 12 and 13, which constitute the inductor of this embodiment,
The gap members 14 and 15 are shown in FIGS. 1 and 2 and FIGS. 3 and 4.
They are formed in the same shape with the same materials as those of the embodiments shown in FIGS. In the third embodiment, the bobbin 21 is provided. The bobbin 21 is made of a non-magnetic material, and the winding 16 is formed on the body portion 21a. A rectangular hole 21b having the same shape as the cross section of the main core 11 is formed in the center of the body portion 21a, and the long side portion 11a of the main core 11 is inserted into the rectangular hole 21b, whereby the winding 16 Are provided in the main core 11.

Collar portions 21c and 2 are provided on both sides of the bobbin 21.
1d is formed, and the winding 16 has the flange portions 21c and 2
It is wound in 1d. Extension parts 2 are provided on the collar parts 21c and 21d.
1e and 21f are integrally formed. As shown in FIG. 5, when the inductor is assembled, the extension portion 21e is
And 21f between the upper and lower connecting cores 12 and 13 (if the gap members 14 and 15 are provided, both gap members 14
Between the upper and lower connecting cores 12 and 13 (the portion without the main core) is supported by the extension portions 21e and 21f.

The main core 11 has a plane L-shape, and each connecting core 1
When 2 and 13 are L-shaped in a plane, the support state of the connecting cores 12 and 13 joined only to both ends of the main core 11 is unstable, but as shown in FIG. The central portion of 13 without the main core is supported by the extension portions 21e and 21f, so that the support state of the connecting cores 12 and 13 is stabilized. In addition, this extension 21e for stability,
By forming 21f integrally with the bobbin 21, the number of parts does not increase extremely. In the embodiment shown in FIGS. 3 and 4, an extension portion may be provided integrally with the collar members 17 and 18, and the extension portions may support the central portions of the connecting cores 12 and 13. In addition, the connecting core 12,
When the core 13 and the main core 31 are firmly adhered to each other, the bobbin 21 may not be provided with the extensions 21e and 21f.

FIG. 7 is a perspective view showing a fourth embodiment of the inductor of the present invention, and FIG. 8 is an exploded perspective view thereof. In this inductor, the planar shape of the main core 31 is a U shape or a U shape. The main core 31 is formed of a laminated body of the same iron-based material as the main core 11 of the embodiment shown in FIGS. 1 and 2, and the thickness dimension t1 and the width dimension w1 are those shown in FIGS. The same, for example 0.5 mm each. The main core 31 is different from the main core 11 shown in FIG.
The portion indicated by is an extended shape. The dimension A of the long side and the dimension B of the short side of the main core 31 correspond to the respective dimensions of the main core shown in FIGS.

Connecting cores 12, 1 in the embodiment of FIGS. 7 and 8
3 is the same as that shown in FIGS. 1 and 2 and has a thickness t2.
Is, for example, 0.25 mm, and the width dimension w1 is, for example, 0.5 mm
The planar shape is L-shaped. The gap members 14 and 15 are formed of a polyimide film having a thickness of 12.5 μm, 25 μm or 50 μm. In the inductor assembled as shown in FIG. 7, the portion (g) at the short side end of the connecting cores 12 and 13 is the main core 31.
The long side portions of the connecting cores 12 and 13 are superposed on the upper and lower surfaces of the main core 31 (to) portion. When the gap material 14 and / or 15 is interposed, the overlapping portion of the (he) is entirely provided with the gap g, and the gap material 14 and / or 15 is provided on the entire surface of the (he).

In this embodiment, as shown in FIG. 7, since the long side portions of the connecting cores 12 and 13 are overlapped with the (to) portion of the main core 31, the supporting of the connecting cores 12 and 13 is stable. To do. Further, in the portion (), the main core 31 and the connecting cores 12 and 13 are surface-joined with each other over a wide area to form a gap g. Therefore, when a predetermined gap distance (gap length) is formed by the gap material, even if the main core 31 and the connecting core 12 or 13 are displaced in a plane, for example, the facing area is large, and thus the plane is large. Errors such as inductance due to the positional displacement are reduced. Therefore, even if the assembly work is a little rough,
The characteristics of the inductor can be made uniform. In addition,
In the embodiment of FIGS. 7 and 8, only one of the connecting cores 12 and 13 may be provided.

FIG. 9 is a perspective view showing an inductor according to the fifth embodiment of the present invention. In this inductor, the main core 32 is formed in a U shape by a laminated body of an iron-based material, and the winding 16 is provided in the connecting portion 32a. Then, the I-shaped connecting cores 33 and 34 are surface-bonded above and below both open ends of the main core 32, and a predetermined thickness of a polyimide film or the like is provided between the main core 32 and the connecting cores 33 and 34 as needed. The gap materials 35 and 36 are inserted.

In the embodiment shown in FIG. 9, the connecting cores 33 and 3 are
4 can be reduced in size, and the overall size can be reduced. However, since the winding 16 is provided in the connecting portion 32a of the main core 32, the bobbin provided with the winding cannot be easily inserted through the main core to be attached. In order to easily mount the bobbin on which the winding is wound, it is preferable to make the main core L-shaped as shown in FIG. Also,
In each of the above-mentioned embodiments, one winding 16 is provided in the main core, which is of the self-induction type. However, both the primary side and the secondary side are provided as windings, and a mutual induction type inductor is provided. May be configured.

[0038]

As described above, in the inductor of the present invention,
Since the connecting core is superposed on the L-shaped or U-shaped main core so as to be in surface contact with each other, it is thin and small, and high inductance can be obtained.

By constructing the main core and the connecting core by a laminated body of an iron-based material, it is possible to perform punching by press working or the like, and it is possible to achieve mass production at low cost.

Since the main core and the connecting core are in surface contact with each other to form a gap, it is easy to set and adjust the area of the gap and the gap. For example, by using a sheet or film gap material, The gap distance between the main core and the connecting core can be set with high accuracy.

Further, if an extension portion is provided from the brim portion that regulates both ends of the winding and the extension core portion supports both connecting cores, the interval between the connecting cores can be maintained with high accuracy and the connecting cores The support can be stabilized.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of an inductor of the present invention,

FIG. 2 is an exploded perspective view of the inductor shown in FIG.

FIG. 3 is a perspective view showing an inductor according to a second embodiment of the present invention,

4 is a perspective view showing a main core and a collar member of the inductor shown in FIG.

FIG. 5 is a perspective view showing a third embodiment of the inductor of the present invention,

6 is an exploded perspective view of the inductor shown in FIG. 5,

FIG. 7 is a perspective view showing a fourth embodiment of the inductor of the present invention,

8 is an exploded perspective view of the inductor shown in FIG. 7,

FIG. 9 is a perspective view showing a fifth embodiment of the inductor of the present invention,

FIG. 10A is a perspective view of a conventional inductor, and FIG.
Is a vertical sectional view of a conventional inductor,

[Explanation of symbols]

 11, 31, 32 Main core 12, 13, 33, 34 Connection core 14, 15, 35, 36 Gap material 16 Winding 17, 18 Collar member 21 Bobbin 21c, 21d Collar portion 21e, 21f Extension portion

Claims (6)

[Claims] 1. A main core having a winding, and a connecting core provided between end portions of the main core, wherein both end portions of the main core and the connecting core are superposed on each other and are in surface contact with each other. Inductor characterized by being. 2. The inductor according to claim 1, wherein a pair of connecting cores are provided with the main core interposed therebetween. 3. The inductor according to claim 1, wherein the main core has an L-shaped or U-shaped planar shape. 4. The inductor according to claim 1, wherein the main core and the connecting core are a laminated body of an iron-based material, and the surface layers of the main core and the connecting core are in surface contact with each other. 5. The inductor according to claim 1, wherein a non-magnetic gap material is interposed between the main core and the connecting core. 6. An extension portion is integrally provided on a collar portion that regulates both end portions of the winding, and the extension portion is interposed between both connecting cores in a portion where there is no main core, so that the connecting cores The inductor according to claim 2, wherein the spacing is maintained.