Coil component

Abstract

To reduce the electrostatic capacitance generated between a winding part of a first wire and a winding part of a second wire that are wound around each other around a winding core part in a coil component with two wires wound around it.SOLUTION: In a winding portion 29 of a first wire 27 and a winding portion 30 of a second wire 28, which are wound around a winding core part in a state where they are next to each other, insulation sheaths 33, 34 have a large diameter portion 35 and small diameter portions 37, 38 with a smaller outer diameter than the large diameter portion 35. Large diameter portions 35, 36 and the small diameter portions 37, 38 are distributed over multiple locations along a direction in which the wires 27, 28 extend. A gap 39 caused by a difference in radial dimension between the large diameter portions 35, 36 and the small diameter portions 37, 38 is formed between the first winding portion 29 and the second winding portion 30. The gap 39 contributes to reducing the electrostatic capacitance.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a coil component having a structure in which at least two wires are wound around a winding core portion provided on a bobbin, and in particular to the form of an insulating coating of the wires. [Background technology]

[0002] Coil components of interest to the present invention include, for example, those constituting a common mode choke coil or a transformer. The coil components constituting the common mode choke coil or the transformer include a bobbin having a winding core for winding a wire, and at least two wires including a first wire and a second wire each wound around the winding core.

[0003] Usually, the first wire and the second wire respectively constitute a first winding portion and a second winding portion that are wound around the winding core, except for both ends of each wire that are connected to terminal electrodes.

[0004] 9, the first wire 1 and the second wire 2 each have a central conductor 3 and 4 made of a highly conductive metal, and insulating coatings 5 ​​and 6 made of an electrically insulating resin that cover the circumferential surfaces of the central conductors 3 and 4. In the first and second winding portions described above, the cross sections of the first wire 1 and the second wire 2 are circular.

[0005] The first wire 1 and the second wire 2 are wound adjacent to each other around the winding core in their respective first and second winding portions as shown in Fig. 9. In this state, if a potential difference exists between the first wire 1 and the second wire 2, a capacitance is generated between the first wire 1 and the second wire 2. If the capacitance is large, it will adversely affect the electrical characteristics of the common mode choke coil or the transformer.

[0006] For this reason, it is desirable to reduce the electrostatic capacitance. For example, JP2017-537462A (Patent Document 1) describes a structure in which a tube section-shaped wall made of an electrically insulating material is disposed between a first wire wound on the inner layer side and a second wire wound on the outer layer side to reduce the electrostatic capacitance. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special Publication No. 2017-537462 Summary of the Invention [Problem to be solved by the invention]

[0008] In the structure described in Patent Document 1, the presence of the tube section-shaped wall prevents the coil component from being miniaturized, and the tube section-shaped wall must be prepared as a separate component, which poses the problem of complicating the manufacturing process for the coil component and increasing costs.

[0009] Therefore, an object of the present invention is to provide a coil component that can solve the above-mentioned problems, i.e., can suppress the generation of stray capacitance without requiring a separate component such as a tube section shaped wall. [Means for solving the problem]

[0010] The present invention is directed to a coil component comprising: a bobbin having a winding core portion; and at least two wires including a first wire and a second wire each wound around the winding core portion and each having a central conductor and an insulating coating made of an electrically insulating resin covering the circumferential surface of the central conductor.

[0011] In the coil component according to the present invention, the first wire and the second wire each have a first winding portion and a second winding portion wound adjacent to each other around a winding core, and in order to solve the above-mentioned technical problem, the insulating coating in at least one of the first winding portion and the second winding portion has a large diameter portion and a small diameter portion having an outer diameter smaller than that of the large diameter portion, and the large diameter portion and the small diameter portion are distributed at multiple points along the extending direction of the wire. Effect of the Invention

[0012] According to this invention, since the insulating coating of the wire has a mixture of large and small diameter portions, a gap is formed between the first and second winding portions due to the difference in radial dimension between the large and small diameter portions. This gap can be filled with air, which has a low dielectric constant, and therefore contributes to reducing the electrostatic capacitance generated between the first and second winding portions. [Brief description of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of a coil device 11 according to a first embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view taken along line AA in FIG. 1, which diagrammatically shows a first winding portion 29 of a first wire 27 and a second winding portion 30 of a second wire 28, which are wound adjacent to each other around a winding core portion in the coil device 11 shown in FIG. 1. [Diagram 3] 3 is a cross-sectional view of a first winding portion 29 of a first wire 27 and a second winding portion 30 of a second wire 28 taken along line BB in FIG. 2. [Figure 4] This is a cross-sectional view corresponding to Figure 2, illustrating a first winding portion 29 of a first wire 27 and a second winding portion 30 of a second wire 28, which are wound adjacent to each other around a winding core portion, for explaining a second embodiment of the present invention. [Diagram 5] 5 is a cross-sectional view of a first winding portion 29 of a first wire 27 and a second winding portion 30 of a second wire 28 taken along line CC in FIG. 4. FIG. [Figure 6] FIG. 10 is a cross-sectional view corresponding to FIG. 2, illustrating a wound portion 29 of a wire 27, for explaining a third embodiment of the present invention. [Figure 7] FIG. 10 is a cross-sectional view corresponding to FIG. 2, illustrating a wound portion 29 of a wire 27, for explaining a fourth embodiment of the present invention. [Figure 8] FIG. 10 is a cross-sectional view corresponding to FIG. 2, illustrating a wound portion 29 of a wire 27, for explaining a fifth embodiment of the present invention. [Figure 9] 1 is a cross-sectional view of a first winding portion of a first wire 1 and a second winding portion of a second wire 2 for explaining the background art of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] With reference to FIG. 1, a schematic configuration of a coil device 11 according to a first embodiment of the present invention will be described.

[0015] The coil component 11 constitutes, for example, a common mode choke coil. The coil component 11 includes a bobbin 12. The bobbin 12 includes a winding core portion 13, and a first flange portion 15 and a second flange portion 16 provided at opposite ends of the winding core portion 13 in the axial direction. The bobbin 12 is preferably made of ferrite. The bobbin 12 may be made of a non-conductive material other than ferrite, for example, a non-magnetic material such as alumina, a resin such as plastic, or a resin containing ferrite powder or metal magnetic powder.

[0016] The winding core 13 and the first and second flanges 15 and 16 of the bobbin 12 are, for example, in the shape of a quadrangular prism having a rectangular cross-sectional shape. Furthermore, the ridges of the quadrangular prism-shaped winding core 13 and the flanges 15 and 16 may be chamfered. The cross-sectional shape of the winding core 13 and the flanges 15 and 16 may be a polygon such as a hexagon, a circle, an ellipse, or a combination of these, in addition to a rectangle.

[0017] The first flange 15 has a bottom surface 17 that faces the mounting board side during mounting, and a top surface 19 that faces in the opposite direction from the bottom surface 17. The second flange 16 is similar to the first flange 15, and has a bottom surface 18 that faces the mounting board side during mounting, and a top surface 20 that faces in the opposite direction from the bottom surface 18.

[0018] Although not shown in detail, a first terminal electrode 21 and a third terminal electrode 23 are provided on a bottom surface 17 of the first flange 15, lined up in a direction perpendicular to the plane of the paper in Fig. 1 and spaced apart from each other. A second terminal electrode 22 and a fourth terminal electrode 24 are provided on a bottom surface 18 of the second flange 16, lined up in a direction perpendicular to the plane of the paper in Fig. 1 and spaced apart from each other. In Fig. 1, the first terminal electrode 21 and the second terminal electrode 22 are shown formed on the outer surfaces of the first flange 15 and the second flange 16, respectively, and the third terminal electrode 23 and the fourth terminal electrode 24 are shown in cross section together with parts of the first flange 15 and the second flange 16.

[0019] The coil component 11 further includes at least two wires each wound around the winding core 13. In this embodiment, the wires include a first wire 27 and a second wire 28. In FIG. 1, the first wire 27 is shaded in order to more clearly distinguish the first wire 27 from the second wire 28 on the drawing. The first wire 27 and the second wire 28 each have a first winding portion 29 and a second winding portion 30 wound around the winding core 13. The first wire 27 is wound so as to form an inner layer with the first winding portion 29, and the second wire 28 is wound so as to form an outer layer with the second winding portion 30. Although not shown, both ends of the first wire 27 are connected to the first terminal electrode 21 and the second terminal electrode 22, respectively, and both ends of the second wire 28 are connected to the third terminal electrode 23 and the fourth terminal electrode 24, respectively. For these connections, for example, thermocompression is applied.

[0020] Fig. 2 is a cross-sectional view taken along line AA in Fig. 1, and shows an enlarged schematic view of the first winding portion 29 of the first wire 27 and the second winding portion 30 of the second wire 28, which are wound around the winding core 13 shown in Fig. 1. As shown in Fig. 2, the first winding portion 29 of the first wire 27 and the second winding portion 30 of the second wire 28 are adjacent to each other. Fig. 3 is a further enlarged view than Fig. 2, and shows a cross-sectional view of the first winding portion 29 of the first wire 27 and the second winding portion 30 of the second wire 28 taken along line BB in Fig. 2.

[0021] 2 and 3, the first wire 27 and the second wire 28 each have a central conductor 31, 32 made of a highly conductive metal such as copper, silver, or gold, and insulating coatings 33, 34 made of an electrically insulating resin such as polyurethane, polyamideimide, or polyester that cover the circumferential surfaces of the central conductors 31, 32. In the first winding portion 29 and the second winding portion 30 described above, the central conductors 31, 32 have a circular cross section and have a substantially constant diameter along the extension direction of the wires 27 and 28.

[0022] On the other hand, the radial dimensions of insulating coatings 33 and 34 vary along the extension direction of wires 27 and 28. That is, insulating coating 33 of first winding portion 29 on the first wire 27 side has large diameter portion 35 and small diameter portion 37 whose outer diameter is smaller than large diameter portion 35. Insulating coating 34 of second winding portion 30 on the second wire 28 side has large diameter portion 36 and small diameter portion 38 whose outer diameter is smaller than large diameter portion 35.

[0023] The large diameter portions 35 and small diameter portions 37 in the insulating coating 33 of the first winding portion 29 are distributed over multiple locations along the extension direction of the first wire 27. The large diameter portions 36 and small diameter portions 38 in the insulating coating 34 of the second winding portion 30 are distributed over multiple locations along the extension direction of the second wire 28.

[0024] In this embodiment, the large diameter portions 35 and small diameter portions 37 on the first winding portion 29 side are alternately arranged at regular intervals along the extension direction of the first wire 27. Similarly, the large diameter portions 36 and small diameter portions 38 on the second winding portion 30 side are alternately arranged at regular intervals along the extension direction of the second wire 28.

[0025] In addition, in terms of the length measured in the direction in which first wire 27 and second wire 28 extend, large diameter portion 35 and large diameter portion 36 are equal to each other, and small diameter portion 37 and small diameter portion 38 are equal to each other.

[0026] The arrangement interval between the large diameter portion 35 and the small diameter portion 37 on the first winding portion 29 side is equal to the arrangement interval between the large diameter portion 36 and the small diameter portion 38 on the second winding portion 30 side. The large diameter portion 33 on the first winding portion 29 side faces the small diameter portion 38 on the second winding portion 30 side, and the small diameter portion 37 on the first winding portion 29 side faces the large diameter portion 36 on the second winding portion 30 side.

[0027] In each of the first winding portion 29 and the second winding portion 30, the thickness of the insulating coatings 33 and 34 in the large diameter portions 35 and 36 is preferably not more than twice the thickness of the insulating coatings 33 and 34 in the small diameter portions 37 and 38. In addition, the thickness of the insulating coatings 33 and 34 in the large diameter portions 35 and 36 is preferably not less than 1.1 times the thickness of the insulating coatings 33 and 34 in the small diameter portions 37 and 38.

[0028] In addition, in this embodiment, the thickness of the insulating coating 33 at the large diameter portion 35 in the first winding portion 29 is substantially equal to the thickness of the insulating coating 34 at the large diameter portion 36 in the second winding portion 30, and the thickness of the insulating coating 33 at the small diameter portion 37 in the first winding portion 29 is substantially equal to the thickness of the insulating coating 34 at the small diameter portion 38 in the second winding portion 30.

[0029] As described above, according to this embodiment, the insulating coatings 33 and 34 include a mixture of the large diameter portions 35 and 36 and the small diameter portions 37 and 38, so that a gap 39 is formed between the first winding portion 29 and the second winding portion 30 due to the difference in radial dimension between the large diameter portions 35 and 36 and the small diameter portions 37 and 38. This gap 39 is usually filled with air, which has a low dielectric constant, and therefore contributes to reducing the electrostatic capacitance generated between the first winding portion 29 and the second winding portion 30. In this embodiment, the gap 39 has a size equivalent to the difference in radial dimension between the large diameter portions 35 and 36 and the small diameter portions 37 and 38.

[0030] When the cross-sectional shape of the winding core is a polygon such as a rectangle, it is preferable that at least one large diameter portion is located on one side of the polygon, or at least one large diameter portion is located on at least one corner of the polygon. When the cross-sectional shape of the winding core is a circle or an ellipse, it is preferable that at least one large diameter portion is located within one revolution.

[0031] In this embodiment, the thickness is varied in two stages, that is, the large diameter portions 35 and 36 and the small diameter portions 3 and 38, but the thickness may be varied in three or more stages.

[0032] Next, a second embodiment of the present invention will be described with reference to Figures 4 and 5. Figure 4 is a cross-sectional view corresponding to Figure 2, and Figure 5 is a view corresponding to Figure 3. In Figures 4 and 5, elements corresponding to those shown in Figures 2 and 3 are given the same reference numerals, and duplicated explanations will be omitted.

[0033] In this embodiment, the large diameter portions 35 and small diameter portions 37 on the first winding portion 29 side are alternately arranged at irregular intervals along the extension direction of the first wire 27. Similarly, the large diameter portions 36 and small diameter portions 38 on the second winding portion 30 side are alternately arranged at irregular intervals along the extension direction of the second wire 28.

[0034] Therefore, there is no particular regularity between the large diameter portion 35 and the small diameter portion 37 on the first winding portion 29 side and the large diameter portion 36 and the small diameter portion 38 on the second winding portion 30 side.

[0035] As a result, some of the large diameter portions 35 on the first winding portion 29 side face the large diameter portion 36 on the second winding portion 30 side, and some of them face the small diameter portion 38 on the second winding portion 30 side. Similarly, some of the small diameter portions 37 on the first winding portion 29 side face the large diameter portion 36 on the second winding portion 30 side, and some of them face the small diameter portion 38 on the second winding portion 30 side.

[0036] As described above, in this embodiment as well, the insulating coatings 33 and 34 have a mixture of large diameter portions 35 and 36 and small diameter portions 37 and 38, so that a gap 40 is formed between the first wound portion 29 and the second wound portion 30 due to the difference in radial dimension between the large diameter portions 35 and 36 and the small diameter portions 37 and 38. In this embodiment, the gap 40 has a size equivalent to twice the difference in radial dimension between the large diameter portions 35 and 36 and the small diameter portions 37 and 38 at its widest point.

[0037] In the first and second embodiments described above, both the first winding portion 29 and the second winding portion 30, which are wound adjacent to each other around the winding core 13, have the large diameter portions 35 and 36 and the small diameter portions 37 and 38, but only one of the first winding portion and the second winding portion may have a large diameter portion and a small diameter portion. Even in this case, a gap can be formed between the first winding portion and the second winding portion due to the difference in radial dimension between the large diameter portion and the small diameter portion.

[0038] In the first and second embodiments, the large diameter portions 35 and 36 have a stepped shape rising from the small diameter portions 37 and 38 in a direction perpendicular to the extension direction of the wires 27 and 28, in other words, have a rectangular cross section, but the shape can be changed as desired.

[0039] 6 to 8 are for explaining still another embodiment of the present invention, and show modified examples of the large diameter portion. Of the first winding portion of the first wire and the second winding portion of the second wire wound adjacent to each other around the winding core, only the winding portion of one of the wires, for example, the first winding portion 29 of the first wire 27, is shown in Fig. 6 to 8. Therefore, in Fig. 6 to 8, the reference numerals related to the first winding portion 29 of the first wire 27 are the same as those used in Fig. 2, and duplicated explanations are omitted. Although not shown, the winding portion of the other wire may or may not have a large diameter portion and a small diameter portion.

[0040] In a third embodiment shown in FIG. 6, a large diameter portion 35 is provided which has a trapezoidal cross section.

[0041] In the fourth embodiment shown in FIG. 7, a large diameter portion 35 is provided which has a triangular cross section.

[0042] In the fifth embodiment shown in FIG. 8, a large diameter portion 35 is provided which has a semi-elliptical cross section.

[0043] As in the first to fifth embodiments described above, in order to vary the radial dimensions of the insulating coatings 33 and 34 along the extension direction of the wires 27 and 28, it is possible to employ a method of varying the amount of insulating coating raw material applied to the circumferential surfaces of the central conductors 31 and 32 to form the insulating coatings 33 and 34, or a method of forming the insulating coatings 33 and 34 to a uniform thickness and then physically removing part of the thickness of the insulating coatings 33 and 34 by locally irradiating them with laser light or applying a sharp rotary blade. Note that the method of peeling off part of the thickness of the insulating coatings 33 and 34 by irradiating them with laser light is preferably performed in parallel with the process of winding the wires 27 and 28 around the winding core 13.

[0044] Although the present invention has been described with reference to the illustrated embodiment, various other embodiments are possible within the scope of the present invention.

[0045] For example, while insulating coatings 33 and 34 are illustrated as having a uniform radial dimension in the circumferential direction, they may have a varying radial dimension in the circumferential direction or may have a varying radial dimension in both the direction of wire extension and the circumferential direction.

[0046] In addition, in the illustrated embodiment, a multi-layer winding is used in which the first wire and the second wire are wound around the winding core, one forming the inner layer and the other forming the outer layer. However, a bifilar winding in which the first wire and the second wire are adjacent to each other in the axial direction of the winding core, a winding in which the first wire and the second wire change their positional relationship and have a crossing structure in some parts, or a twisted winding in which the first wire and the second wire are twisted together and wound may also be used.

[0047] In addition, in this invention, since a gap is formed between the first winding part and the second winding part due to the difference in radial dimension between the large diameter part and the small diameter part due to the mixture of large diameter part and small diameter part in the insulating coating of the wire, and since the effect of reducing the capacitance is sought, it is preferable that the gap is filled with air having a low dielectric constant. However, even if the coil component is impregnated with, for example, resin and the gap is filled with resin, the effect of reducing the capacitance can be maintained as long as the relative dielectric constant of the resin is lower than that of the insulating coating.

[0048] Further, the above-described embodiment relates to a coil component constituting a common mode choke coil, but the coil component may also be one constituting another type of transformer or the like.

[0049] Furthermore, the above-described embodiments are merely illustrative, and partial substitution or combination of configurations is possible between different embodiments.

[0050] The embodiments of the present invention include the following.

[0051] <1> A bobbin having a winding core portion; At least two wires including a first wire and a second wire each wound around the winding core portion, each having a central conductor and an insulating coating made of an electrically insulating resin covering a circumferential surface of the central conductor; Equipped with the first wire and the second wire each have a first winding portion and a second winding portion wound adjacent to each other around the winding core; In at least one of the first winding portion and the second winding portion, the insulating coating has a large diameter portion and a small diameter portion having an outer diameter smaller than that of the large diameter portion, and the large diameter portion and the small diameter portion are distributed at a plurality of locations along the extending direction of the wire. Coil parts.

[0052] <2> The large diameter portions and the small diameter portions are alternately arranged at regular intervals along the extending direction of the wire. <1> The coil component according to claim 1.

[0053] <3> The large diameter portions and the small diameter portions are alternately arranged at irregular intervals along the extending direction of the wire. <1> The coil component according to claim 1.

[0054] <4> The thickness of the insulating coating at the large diameter portion is not more than twice the thickness of the insulating coating at the small diameter portion. <1> Or <3> 2. The coil component according to claim 1 .

[0055] <5> In both the first winding portion and the second winding portion, the first wire and the second wire have the large diameter portion and the small diameter portion. <1> Or <4> 2. The coil component according to claim 1 .

[0056] <6> The large diameter portion on the first winding portion side faces the large diameter portion on the second winding portion side. <5> The coil component according to claim 1.

[0057] <7> The large diameter portion on the first winding portion side faces the small diameter portion on the second winding portion side. <5> or <6> The coil component according to claim 1.

[0058] <8> The first wire and the second wire are wound around the winding core such that one forms an inner layer and the other forms an outer layer. <1> Or <7> 2. The coil component according to claim 1 .

[0059] <9> The coil component constitutes a common mode choke coil. <1> Or <8> 2. The coil component according to claim 1 .

[0060] <10> The coil component constitutes a transformer. <1> Or <8> 2. The coil component according to claim 1 . [Explanation of symbols]

[0061] 11 Coil parts 12 Bobbin 13 Winding core 27 First Wire 28 Second Wire 29 Volume 1 Part 30 Volume 2 Part 31,32 Center conductor 33,34 Insulating coating 35,36 Large diameter part 37,38 Small diameter part 39,40 Gap

Claims

1. A bobbin having a winding core portion; At least two wires including a first wire and a second wire each wound around the winding core portion, each having a central conductor and an insulating coating made of an electrically insulating resin covering a circumferential surface of the central conductor; Equipped with the first wire and the second wire each have a first winding portion and a second winding portion wound adjacent to each other around the winding core; In at least one of the first winding portion and the second winding portion, the insulating coating has a large diameter portion and a small diameter portion having an outer diameter smaller than that of the large diameter portion, and the large diameter portion and the small diameter portion are distributed at a plurality of locations along the extending direction of the wire. Coil parts.

2. The coil component according to claim 1 , wherein the large diameter portions and the small diameter portions are alternately arranged at regular intervals along an extending direction of the wire.

3. The coil component according to claim 1 , wherein the large diameter portions and the small diameter portions are alternately arranged at irregular intervals along an extending direction of the wire.

4. 2. The coil component according to claim 1, wherein a thickness of the insulating coating at the large diameter portion is not more than twice a thickness of the insulating coating at the small diameter portion.

5. The coil component according to claim 1 , wherein in both the first winding portion and the second winding portion, the first wire and the second wire have the large diameter portion and the small diameter portion.

6. The coil component according to claim 5 , wherein the large diameter portion on the first winding portion side includes a portion that faces the large diameter portion on the second winding portion side.

7. The coil component according to claim 5 , wherein the large diameter portion on the first winding portion side faces the small diameter portion on the second winding portion side.

8. The coil component according to claim 1 , wherein the first wire and the second wire are wound around the winding core such that one forms an inner layer and the other forms an outer layer.

9. The coil component according to claim 1 , which constitutes a common mode choke coil.

10. The coil component according to claim 1 , which constitutes a transformer.

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