Coil device

Abstract

To provide a coil device which can be reduced in size while ensuring leakage.SOLUTION: Provided is a coil device 1 including: a bobbin 10; a first wire 70 having a first coil 74 that is wound on the bobbin 10; a second wire 80 having a second coil 84 that is wound on the bobbin 10; and cores 60a, 60b attached to the bobbin 10. Main middle legs 64a, 64b of the respective cores 60a,60b are arranged inside the first coil 74 and the second coil 84, respectively. First sub middle legs 66a1, 66b1 of the respective cores 60a, 60b are arranged outside the second coil 84 and inside the first coil 74. Second sub middle legs 66a2, 66b2 of the respective cores 60a, 60b are arranged inside the second coil 84 and outside the first coil 74.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a coil device suitably used, for example, as a leakage transformer.

Background Art

[0002] A leakage transformer is used as a composite transformer having a function of a choke coil in addition to the function of a transformer. In a leakage transformer, since the leakage serves as a function of a choke coil, there is an advantage that the structure of the choke coil can be omitted, contributing to miniaturization of the transformer.

[0003] Patent Document 1 discloses a horizontal leakage transformer in which a secondary coil is disposed inside a primary coil, and a vertical leakage transformer in which a primary coil and a secondary coil are wound coaxially and disposed vertically.

[0004] However, in any transformer, a certain distance must be provided between the primary coil and the secondary coil to ensure leakage, making it difficult to miniaturize the transformer.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In view of such a situation, the present invention has been made, and an object thereof is to provide a coil device capable of ensuring leakage and being miniaturized.

Means for Solving the Problems

[0007] To achieve the above object, a coil device according to the present invention includes a bobbin, A first wire having a first coil portion wound around the bobbin, A second wire having a second coil portion wound around the bobbin, A coil device having a core attached to the bobbin, wherein The core has A base portion extending in a first axial direction, A main middle leg portion disposed substantially at the center of the base portion in the first axial direction, A first sub-middle leg portion disposed on one side of the main middle leg portion in the first axial direction in the base portion, A second sub-middle leg portion disposed on the other side of the base portion in the first axial direction, and the main middle leg portion is disposed inside the first coil portion and the second coil portion, The first sub-middle leg portion is disposed inside the first coil portion and outside the second coil portion, The second sub-middle leg portion is disposed inside the second coil portion and outside the first coil portion.

[0008] By configuring in this way, even if the respective coils are close to each other, leakage flux is generated through the sub-middle leg portions, leakage can be ensured, and miniaturization of the coil device can be realized. Further, by configuring in this way, the AC resistance can be suppressed and an increase in copper loss can be suppressed.

[0009] Furthermore, according to this configuration, it is also easy to adjust the turns ratio between the primary coil and the secondary coil. For example, in a conventional horizontal leakage transformer, when the turns ratio of each coil is set to 1:1 to make the inductances uniform, it has been difficult to ensure leakage while keeping the size small. However, according to the above-described configuration, even when the turns ratio of each coil is set to 1:1 and the inductances of the respective coils are made uniform, leakage can be easily ensured.

[0010] Preferably, the core has a first outer leg portion and a second outer leg portion disposed on the base portion. The first sub-middle leg portion is disposed between the first outer leg portion and the main middle leg portion, and the second sub-middle leg portion is disposed between the second outer leg portion and the main middle leg portion. The first outer leg portion is disposed outside the first coil portion, and the second outer leg portion is disposed outside the second coil portion. By configuring in this way, each coil portion is accommodated between the outer leg portions, and miniaturization of the coil device can be achieved.

[0011] Preferably, the core has a first core portion including at least a first base portion which is a part of the base portion, and a second core portion including at least a second base portion which is another part of the base portion and is substantially parallel to the first base portion. The first core portion and the second core portion sandwich the first coil portion and the second coil portion along the winding axis of the first coil portion. By configuring in this way, each coil is accommodated between the base portions, and miniaturization of the coil device can be achieved.

[0012] Preferably, the bobbin has a first winding portion around which the first coil portion is wound, a second winding portion around which the second coil portion is wound, and a winding partition flange separating the first winding portion and the second winding portion. In the first winding portion, a first main through hole in which the main middle leg portion is disposed and a first sub-through hole in which the first sub-middle leg portion is disposed are formed. In the second winding portion, a second main through hole in which the main middle leg portion is disposed and a second sub-through hole in which the second sub-middle leg portion is disposed are formed. The first main through hole and the second main through hole communicate with each other. With such a configuration, the first wire and the second wire can be insulated, and each wire and the core can be surely insulated.

[0013] [[ID=I2]]Preferably, the cross-sectional area of the main middle leg portion is substantially the same as the sum of the cross-sectional areas of the first outer leg portion and the second outer leg portion. More preferably, the cross-sectional area of the main middle leg portion is larger than the cross-sectional area of the first sub-middle leg portion.

[0014] Preferably, the core is symmetric with respect to a symmetry axis orthogonal to the first axial direction. By configuring in this way, it is easy to set the turn ratio of the first coil part and the second coil part to 1:1 and further to equalize the inductance of each coil.

[0015] In addition, a first gap may be formed in the first sub-middle leg portion. The leakage can be adjusted by the first gap. Also, a second gap may be formed in the main middle leg portion, and preferably, the distance of the first gap is longer than the distance of the second gap. These gaps can prevent the legs from cracking.

[0016] Preferably, the first core portion and the second core portion are symmetric along the winding axis of the first coil portion. Note that the core may be divided along the first axis and a second axis perpendicular to the winding axis of the first coil portion.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2A

Figure 2B

Figure 2C

Figure 3

Figure 4A

Figure 4B

Figure 4C

Figure 4D

Figure 4E

Figure 5A

Figure 5B

Figure 6

Figure 7

[0018] Hereinafter, the present invention will be described based on the embodiments shown in the drawings.

[0019] As shown in FIG. 1, the transformer 1 as the coil device according to the present embodiment is used, for example, as a leakage transformer or the like, and is used in an in-vehicle charger for an electric vehicle, a general-purpose power supply, or the like.

[0020] As shown in FIG. 1, the transformer 1 includes a first wire 70 and a second wire 80, a bobbin 10 around which the wires are wound, cores 60a and 60b that sandwich the bobbin 10 along the Z axis, and a case 90 that houses these components. In the drawings, the X axis, the Y axis, and the Z axis are perpendicular to each other, and the Z axis corresponds to the height (thickness) of the transformer 1. In the present embodiment, the lower side in the Z-axis direction of the transformer 1 is the installation surface of the transformer 1. Further, the X axis coincides with the direction in which the base portion 62b of the core 60b extends. Furthermore, the Y axis is made to coincide with the direction in which the split cores 61b and 61b of the core 60b are arranged.

[0021] In the specification, the direction in which the core 60b is arranged may be expressed as "upward", and the direction in which the core 60a is arranged may be expressed as "downward". In the specification, the side closer to the center of the transformer 1 may be expressed as "inner side", and the side farther from the center may be expressed as "outer side".

[0022] In this embodiment, as shown in FIG. 7, the case 90 is formed of a plate-like member, is open upward in the Z-axis direction, and a bottom plate 92 is formed below in the Z-axis direction. Fixing portions 91 are formed at the four corners of the bottom plate 92. The case 90 is preferably made of a metal such as aluminum copper or iron with excellent heat dissipation properties, but may also be made of PPS, PET, PBT, etc. Since the lower end surface of the core 60a in the Z-axis direction, which will be described later, comes into contact with the bottom plate 92, the bottom plate 92 is preferably made of a material with excellent heat dissipation properties. Below the case 90, a cooling device such as a cooling pipe or cooling fins may be attached via the bottom plate 92 or directly.

[0023] The inside of the case 90 may be filled with a heat-dissipating resin. The heat-dissipating resin is not particularly limited, but for example, a resin with excellent heat dissipation properties having a thermal conductivity of 0.5 to 5, preferably 1 to 3 W / m·K is preferable. Examples of resins with excellent heat dissipation properties include silicone-based resins, urethane-based resins, and epoxy-based resins.

[0024] In addition, the heat-dissipating resin of this embodiment preferably absorbs the deformation even if the cores 60a and 60b or the bobbin 10 are deformed by heat and does not generate excessive stress on the cores 60a and 60b. Examples of such resins include potting resins.

[0025] As shown in FIG. 1, in this embodiment, the core 60a has a base portion 62a that becomes the first core portion shown in FIG. 5A. The base portion 62a is arranged below the bobbin 10 in the Z-axis direction. The core 60b has a base portion 62b that becomes the second core portion. The base portion 62b is arranged above the bobbin 10 in the Z-axis direction. In this embodiment, the material of each of the cores 60a and 60b includes soft magnetic materials such as metal and ferrite, but is not particularly limited.

[0026] The cores 60a and 60b are symmetrical along the Z-axis. As shown in FIG. 5A, the core 60a can be separated into two split cores 61a and 61a with the same shape by split surfaces 611a respectively. The core 60b can be separated into two split cores 61b and 61b with the same shape by split surfaces 611b respectively. In this embodiment, all of the split cores 61a, 61a and 61b, 61b have the same shape.

[0027] Hereinafter, the split core 61a will be described, and the description of the split core 61b will be omitted unless otherwise specified. The split core 61a is symmetrical with respect to a symmetry axis (Z-axis) orthogonal to the X-axis direction.

[0028] As shown in FIG. 5A, the base portion 62a of the split core 61a extends along the X-axis. Inclined surfaces 63a1 and 63a1 are formed outside the center of the base portion 62a in the Y-axis direction and toward the center of the X-axis.

[0029] A main middle leg portion 64a protruding upward in the Z-axis direction is formed on the base portion 62a. The main middle leg portion 64a is disposed substantially at the center of the base portion 62a in the X-axis direction.

[0030] In addition, a first outer leg portion 68a1 and a second outer leg portion 68a2 protruding upward in the Z-axis direction are formed on the base portion 62a. The first outer leg portion 68a1 is disposed at one end of the base portion 62a in the X-axis direction, and the second outer leg portion 68a2 is disposed at the other end of the base portion 62a in the X-axis direction.

[0031] In addition, a first sub-middle leg portion 66a1 and a second sub-middle leg portion 66a2 protruding upward in the Z-axis direction are formed on the base portion 62a. The first sub-middle leg portion 66a1 is disposed between the first outer leg portion 68a1 and the main middle leg portion 64a. The second sub-middle leg portion 66a2 is disposed between the second outer leg portion 68a2 and the main middle leg portion 64a.

[0032] As shown in FIG. 1, the split core 61a is disposed below the bobbin 10 in the Z-axis direction, and the split core 61b is disposed below the bobbin 10 in the Z-axis direction. As shown in FIG. 5B, the end faces 69a1 and 69b1 of the first outer leg portions 68a1 and 68b1 are respectively joined along the Z-axis, and the end faces 69a2 and 69b2 of the second outer leg portions 68a2 and 68b2 are respectively joined along the Z-axis.

[0033] As shown in FIG. 5B, a gap 100a (first gap) with a distance T1 is formed between the end face 67a1 along the Z-axis of the first sub-middle leg portion 66a1 and the end face 67b1 along the Z-axis of the first sub-middle leg portion 66b1. A gap 100b (first gap) with a distance T1 is formed between the end face 67a2 along the Z-axis of the second sub-middle leg portion 66a2 and the end face 67b2 along the Z-axis of the second sub-middle leg portion 66b2.

[0034] A gap 101 (second gap) with a distance T2 is formed between the end face 65a along the Z-axis of the main middle leg portion 64a and the end face 65b along the Z-axis of the main middle leg portion 64b. As shown in FIG. 5B, T1 is configured to be longer than T2.

[0035] In the present embodiment, the cross-sectional area S1 along the Z-axis of the main middle leg portion 64a shown in FIG. 3 is configured to be larger than the cross-sectional area S2 along the Z-axis of the first sub-middle leg portion 66a1 and the second sub-middle leg portion 66a2. Further, the cross-sectional area S1 along the Z-axis of the main middle leg portion 64a is substantially the same as the total S3 of the cross-sectional areas along the Z-axis of the first outer leg portion 68a1 and the second outer leg portion 68a2.

[0036] As shown in FIG. 4C, the bobbin 10 has a first end partition flange 30, a second end partition flange 32, and a winding partition flange 34. A first winding portion 40 serving as the main body of the bobbin is formed between the first end partition flange 30 and the winding partition flange 34. A second winding portion 50 serving as the main body of the bobbin is formed between the second end partition flange 32 and the winding partition flange 34. The bobbin 10 is made of, for example, a plastic such as PPS, PET, PBT, LCP, nylon, etc., but may be made of other insulating members.

[0037] As shown in FIG. 4A, the first end partition flange 30 is disposed above the first winding portion 40 in the Z-axis direction. Outside the center of the first end partition flange 30 along the Y-axis, a first lead extraction table 12 is formed. Inside the first lead extraction table 12 along the Y-axis, tapered surfaces 12a, 12a inclined toward the center of the X-axis are formed. The tapered surfaces 12a, 12a are formed so as to contact inclined surfaces 63b1, 63b1 outside the center of the base portion 62b of one of the split cores 60b shown in FIG. 5A along the Y-axis.

[0038] As shown in FIG. 4A, the first lead extraction table 12 is formed with first passage portions 16a, 16b extending along the Z-axis, and a separation convex portion 13 is formed between the first passage portions 16a, 16b. Outside the center of the first lead extraction table 12 in the Y-axis direction, first lead placement portions 14a, 14b are formed. The first lead placement portions 14a, 14b are formed with first groove portions 14a1, 14b1 extending outside the center in the Y-axis direction. The inside of the first groove portions 14a1, 14b1 in the Y-axis direction is connected to the upper side of the first passage portions 16a, 16b in the Z-axis direction.

[0039] As shown in FIG. 4A, a second lead extraction table 22 is formed on the first end partition flange 30. The second lead extraction table 22 is disposed outside the center in the Y-axis direction opposite to the first lead extraction table 12.

[0040] Inside the second lead extraction table 22 along the Y-axis, tapered surfaces 22a, 22a inclined toward the center of the X-axis are formed. The tapered surfaces 22a, 22a are formed so as to contact inclined surfaces 63b2, 63b2 outside the center of the base portion 62b of the other split core 60b shown in FIG. 5A along the Y-axis.

[0041] As shown in FIG. 4A, the second lead extraction table 22 is formed with a second passage portion 26 extending along the Z-axis. Outside the center of the second lead extraction table 22 in the Y-axis direction, second lead placement portions 24a, 24b are formed.

[0042] As shown in FIG. 4B, second lead placement portions 24a and 24b are formed with second groove portions 24a1 and 24b1. The second groove portion 24a1 is L-shaped having a first portion along the X-axis and a second portion along the Y-axis. The first portion of the second groove portion 24a1 is connected to the second passage portion 26, and the second portion of the second groove portion 24a1 extends outward from the center in the Y-axis direction. The first portion of the second groove portion 24b1 is connected to the upper side in the Z-axis direction of the second passage portion 26.

[0043] The first end partition flange 30 is formed with a first insertion hole 31. The first insertion hole 31 corresponds to the shape of the second sub-middle leg portions 66b2 and 66b2 shown in FIG. 5A. The first insertion hole 31 is arranged to overlap with the second sub-through hole 54. The second sub-middle leg portion 66b2 is inserted into the first insertion hole 31.

[0044] As shown in FIG. 4C, the first winding portion 40 extends along the Z-axis. The central axis O1 of the first winding portion 40 (the winding axis of the first coil portion 74 shown in FIG. 2B) is arranged outside along the X-axis with respect to the central axis O of the first main through hole 42. Along the peripheral surface 41 of the first winding portion 40, the first coil portion 74 shown in FIG. 2B is formed. Note that the central axis O1 and the central axis O are parallel to the Z-axis.

[0045] As shown in FIG. 4D, the first winding portion 40 has a first main through hole 42. As shown in FIG. 2C, the first main through hole 42 communicates with the second main through hole 52. The first main through hole 42 corresponds to the shape of the main middle leg portions 64b and 64b shown in FIG. 5A. As shown in FIG. 4D, split pieces 47 and 47 are formed in the first main through hole 42. The split pieces 47 and 47 abut against the split surfaces 611b of the main middle leg portions 64b and 64b shown in FIG. 5A, and split the split cores 61b and 61b along the Y-axis.

[0046] As shown in FIG. 4D, the first winding portion 40 has a first sub-through hole 44. As shown in FIG. 2C, the first sub-through hole 44 is connected to the winding partition flange 34. The first sub-through hole 44 corresponds to the shape of the first sub-middle leg portions 66b1, 66b1 shown in FIG. 5A. As shown in FIG. 4D, a split piece 48 is formed in the first sub-through hole 44. The split piece 48 abuts against the split surface 611b of the first sub-middle leg portions 66b1, 66b1 shown in FIG. 5A, and splits the split cores 61b, 61b along the Y axis.

[0047] As shown in FIG. 4D, a first insulating wall 46 is formed between the first main through hole 42 and the first sub-through hole 44. The first insulating wall 46 is disposed between the main middle leg portions 64b, 64b and the first sub-middle leg portions 66b1, 66b1 shown in FIG. 5A, and insulates the main middle leg portions and the first sub-middle leg portions.

[0048] As shown in FIG. 4C, a winding partition flange 34 is formed below the first winding portion 40 in the Z-axis direction. A notch 35 is formed in the winding partition flange 34 at a position corresponding to the lower part of the second passage portion 26 in the Z-axis direction. That is, the notch 35 is disposed offset to the outside from the center in the X-axis direction. As shown in FIG. 2B, the second lead portions 82a, 82b are drawn out upward in the Z-axis direction from the second coil portion 84 through the notch 35 and the second passage portion 26.

[0049] As shown in FIG. 4C, the second winding portion 50 extends along the Z axis. The central axis O2 of the second winding portion 50 (the winding axis of the second coil portion 84 shown in FIG. 2B) is disposed outside along the X axis with respect to the center line O of the second main through hole 52 (the central axis O of the main through hole 42 shown in FIG. 4A). Note that the central axis O2 is parallel to the Z axis.

[0050] In the present embodiment, the second winding portion 50 has a shape corresponding to that of the first winding portion 40. With the center line Lx passing through the central axis O shown in FIGS. 4D and 4E and parallel to the X axis as the axis of symmetry, the first winding portion 40 and the second winding portion 50 are symmetric respectively.

[0051] As shown in FIG. 4E, the second winding portion 50 has a second main through hole 52. As shown in FIG. 2C, the second main through hole 52 corresponds to the shape of the main middle leg portions 64a, 64a shown in FIG. 5A. As shown in FIG. 4E, split pieces 57, 57 are formed in the second main through hole 52. The split pieces 57, 57 abut against the split surfaces 611a of the main middle leg portions 64a, 64a shown in FIG. 5A, and split the split cores 61a, 61a along the Y-axis.

[0052] As shown in FIG. 4E, the second winding portion 50 has a second sub through hole 54. As shown in FIG. 2C, the second sub through hole 54 is connected to the winding partition flange 34. The second sub through hole 54 corresponds to the shape of the second sub middle leg portions 66a2, 66a2 shown in FIG. 5A. As shown in FIG. 4E, a split piece 58 is formed in the second sub through hole 54. The split piece 58 abuts against the split surfaces 611a of the second sub middle leg portions 66a2, 66a2 shown in FIG. 5A, and splits the split cores 61a, 61a along the Y-axis.

[0053] As shown in FIG. 4E, a second insulating wall 56 is formed between the second main through hole 52 and the second sub through hole 54. The second insulating wall 56 is disposed between the main middle leg portions 64a, 64a and the second sub middle leg portions 66a1, 66a1 shown in FIG. 5A, and insulates the main middle leg portions and the second sub middle leg portions.

[0054] As shown in FIG. 4A, the second end partition flange 32 is disposed below the second winding portion 50 in the Z-axis direction. Convex portions 32a, 32b are formed on both outer sides with respect to the center of the second end partition flange 32 along the Y-axis.

[0055] On the inner sides of the convex portions 32a, 32b along the Y-axis, tapered surfaces 32a1, 32b1 that are inclined toward the center of the X-axis in the same manner as the tapered surfaces 12a, 12a are formed. The tapered surface 32a1 is formed so as to contact the inclined surface 63a1 outside the center along the Y-axis of the base portion 62a of the split core 61a shown in FIG. 5A. The tapered surface 32a2 is formed so as to contact the inclined surface 63a2.

[0056] The second end partition flange 32 is formed with a second insertion hole 33. The second insertion hole 33 corresponds to the shapes of the first sub-middle leg portions 66a1, 66a1 shown in FIG. 5A. The second insertion hole 33 is arranged so as to overlap with the first sub-through hole 44. The first sub-middle leg portion 66a1 is inserted into the second insertion hole 33.

[0057] As shown in FIGS. 2A and 2B, a first wire 70 and a second wire 80 are wound around a bobbin 10. Each of the wires 70, 80 may be made of the same material or different materials. The outer diameters of the respective wires 70, 80 are not particularly limited, but are preferably in the range of 1.0 to 4.0 mm. Further, it is preferable that an insulating coating is formed on each of the wires 70, 80.

[0058] The first wire 70 has a first coil portion 74 wound around the first winding portion 40 of the bobbin 10, and the second wire 80 has a second coil portion 84 wound around the second winding portion 50 of the bobbin 10. As shown in FIG. 2C, the first coil portion 74 is arranged between the first end partition flange 30 and the winding partition flange 34. The second coil portion 84 is arranged between the second end partition flange 32 and the winding partition flange 34.

[0059] As shown in FIGS. 2A and 2B, the winding axis O1 of the first coil portion 74 is displaced to one side along the X axis from the center line O of the transformer (the central axis O of the first main through hole 42 and the second main through hole 52 shown in FIG. 4A). Further, the winding axis O2 of the second coil portion 84 is displaced to the opposite side of the winding axis O1 of the first coil portion 74 along the X axis from the center line O. The winding axis O1 of the first coil portion 74 and the winding axis O2 of the second coil portion 84 are aligned in the Z-axis direction.

[0060] As shown in FIG. 3, the first coil portion 74 has a first coil outer portion 76 arranged outside the center along the X axis with respect to a center line L1 passing through the winding axis O1 and along the Y axis, and a first coil inner portion 78 arranged inside the center along the X axis with respect to the center line L1.

[0061] As shown in FIG. 2C, the outer portion 76 of the first coil passes between the first outer leg portion 68b1 and the first sub-middle leg portion 66b1. Also, the inner portion 78 of the first coil passes between the main middle leg portion 64b and the second sub-middle leg portion 66b2.

[0062] As shown in FIG. 6, the first wire 70 has first lead portions 72a and 72b drawn from the first coil portion 74. Connection terminals 73, which are formed of, for example, metal terminals, are electrically connected to each end of the first lead portions 72a and 72b by soldering or the like.

[0063] As shown in FIG. 2A, the first lead portion 72a is drawn upward in the Z-axis direction toward the first passage portion 16a. The first lead portion 72a passes through the first groove portion 14a1 and is drawn outward from the center in the Y-axis direction.

[0064] As shown in FIG. 2A, the first lead portion 72b is drawn upward in the Z-axis direction toward the first passage portion 16b. The first lead portion 72b passes through the first groove portion 14b1 and is drawn outward from the center in the Y-axis direction.

[0065] As shown in FIG. 3, the second coil portion 84 has a second coil outer portion 86 disposed outside along the X-axis from the center line L2 along the Y-axis passing through the winding axis O2, and a second coil inner portion 88 disposed inside along the X-axis from the center line L2.

[0066] As shown in FIG. 2C, the second coil outer portion 86 passes between the second outer leg portion 68a2 and the second sub-middle leg portion 66a2. Also, the second coil inner portion 88 passes between the main middle leg portion 64a and the first sub-middle leg portion 66a1.

[0067] As shown in FIG. 6, the second wire 80 has second lead portions 82a and 82b drawn from the second coil portion 84. Connection terminals 83, which are formed of, for example, metal terminals, are electrically connected to each end of the second lead portions 82a and 82b by soldering or the like.

[0068] As shown in FIG. 2B, the second lead portions 82a and 82b are drawn upward in the Z-axis direction through the notch 35 and toward the second passage portion 26. The second lead portion 82a is drawn from the second passage portion 26 through the first portion of the second groove portion 24a1 and the second portion of the second groove portion 24a1 shown in FIG. 4B and outward from the center in the Y-axis direction. By configuring in this way, the second lead portion 82a is drawn out while maintaining insulation from the first coil portion 74.

[0069] As shown in FIG. 2B, the second lead portion 82b is drawn upward in the Z-axis direction toward the second passage portion 26b. The second lead portion 82b is drawn through the second groove portion 24b1 and outward from the center in the Y-axis direction.

[0070] In the present embodiment, as shown in FIG. 2C, the first coil portion 74 is wound around the first winding portion 40, and the second coil portion 84 is wound around the second winding portion 50. The first winding portion 40 and the second winding portion 50 are separated by the winding partition flange 34, and insulation between the first coil portion 74 and the second coil portion 84 is ensured.

[0071] In the first winding portion 40, a first main through hole 42 in which the main middle leg portion 64b is disposed and a first sub through hole 44 in which the first sub middle leg portion 66b1 is disposed are formed. Therefore, the main middle leg portion 64b and the first sub middle leg portion 66b1 are disposed inside the first coil portion 74, and insulation between the first coil portion 74 and the core 60b is ensured.

[0072] In the second winding portion 50, a second main through hole 52 in which the main middle leg portion 64a is disposed and a second sub through hole 54 in which the second sub middle leg portion 66a2 is disposed are formed. Therefore, the main middle leg portion 64a and the second sub middle leg portion 66a2 are disposed inside the second coil portion 84, and insulation between the second coil portion 84 and the core 60a is ensured.

[0073] The second sub-middle leg portion 66b2 of the core 60b is disposed between the second outer leg portion 68b2 of the core 60b and the first coil inner portion 78 of the first coil portion 74. That is, the second sub-middle leg portion 66b2 is disposed outside the first coil portion 74. Also, the first sub-middle leg portion 66a1 of the core 60a is disposed between the first outer leg portion 68a1 of the core 60a and the second coil inner portion 88 of the second coil portion 84. That is, the first sub-middle leg portion 66a1 is disposed outside the second coil portion 84.

[0074] With the coil and the sub-middle leg portion arranged in this way, even if the distance between the coils is not increased significantly, leakage magnetic flux is generated in the sub-middle leg portion, ensuring leakage, and the structure of the choke coil can be omitted, realizing miniaturization of the transformer 1. Also, the transformer 1 has a reduced AC resistance and can achieve low copper loss.

[0075] In this embodiment, as shown in FIG. 5A, the core 60a can be divided into divided cores 61a, 61a, and the divided cores 61a, 61a are symmetric with each other. The core 60b can be divided into divided cores 61b, 61b, and the divided cores 61b, 61b are symmetric with each other. Such a configuration facilitates attaching the core to the bobbin.

[0076] Also, the divided core 61a and the divided core 61b are symmetric with each other, and each divided core has a symmetric structure with respect to the Z axis. Therefore, the divided cores can be interchanged and still function in the same way, reducing the manufacturing cost.

[0077] In this embodiment, as shown in FIG. 3, the winding axis O1 of the first coil portion 74 and the winding axis O2 of the second coil portion 84 are a horizontal leakage transformer shifted along the X axis. However, as shown in FIGS. 4D and 4E, the first winding portion 40 and the second winding portion 50 have corresponding shapes of the same size. Therefore, as shown in FIG. 2C, by setting the turns ratio of the first coil portion 74 and the second coil portion to 1:1, it is easy to equalize the inductances of each. According to such a transformer 1, switching loss can be prevented.

[0078] In this embodiment, as shown in FIG. 2C, a base portion 62a disposed below in the Z-axis direction and extending in the X-axis direction and a base portion 62b disposed above in the Z-axis direction and extending in the X-axis direction sandwich the first coil portion 74 and the second coil portion 84. Further, a first outer leg portion and a second outer leg portion extending along the Z-axis sandwich the first coil portion 74 and the second coil portion 84 from both sides in the X-axis direction. By configuring in this way, the first coil portion 74 and the second coil portion 84 can be accommodated between the cores 60a and 60b, and a small transformer having a substantially rectangular parallelepiped outer shape can be manufactured.

[0079] In this embodiment, as shown in FIG. 5B, a gap 100a with a distance T1 is formed between the first sub-middle leg portions 66a1 and 66b1, and a gap 100b with a distance T1 is formed between the second sub-middle leg portions 66a2 and 66b2. Further, a gap 101 with a distance T2 is formed between the main middle leg portion 64a and the main middle leg portion 64b. The distance T1 is configured to be longer than the distance T2. The transformer 1 can adjust leakage through these gaps, and further can prevent cracking of the leg portions. Note that the distances of these gaps can be changed as needed, and it can function as a leakage transformer even without providing the gaps.

[0080] Note that the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention.

[0081] In the above-described embodiment, as shown in FIG. 5A, the cores 60a and 60b are both E-shaped cores having five legs, but either one of the cores may be an I-shaped core having no legs. In this case, the legs of the E-shaped core are butted against the I-shaped core.

Explanation of Reference Numerals

[0082] 1... Transformer 10... Bobbin 12... First lead-out table 13... Separation convex portion 14a, 14b… First lead placement part 14a1, 14b1… First groove part 16a, 16b… First passage part 22… Second lead extraction table 24a, 24b… Second lead placement part 24a1, 24b1… Second groove part 26… Second passage part 30… First end part partition flange 31… First insertion hole 32… Second end part partition flange 32a, 32b… Convex part 33… Second insertion hole 34… Winding partition flange 35… Notch 40… First winding part 41… Peripheral surface 42… First main through hole 44… First sub-through hole 46… First insulating wall 47, 48… Dividing piece 50… Second winding part 51… Peripheral surface 52… Second main through hole 54… Second sub-through hole 56… Second insulating wall 57, 58… Dividing piece 60a, 60b… Core 61a, 61b… Split core 611a, 611b… Split surface 62a… Base part (first part of core) 62b… Base part (second part of core) 63a1, 63a2, 63b1, 63b2… Inclined surface 64a, 64b… Main middle leg part 65a, 65b… End face 66a1, 66b1… First sub-middle leg part 66a2, 66b2… Second sub-middle leg part 67a1, 67b1… End face 67a2, 67b2… End face 68a1, 68b1… First outer leg part 68a2, 68b2… Second outer leg part 69a1, 69b1… End face 69a2, 69b2… end faces 70… first wire 72a, 72b… first lead portions 73… connection terminal 74… first coil portion 76… first coil outer portion 78… first coil inner portion 80… second wire 82a, 82b… second lead portions 83… connection terminal 84… second coil portion 86… second coil outer portion 88… second coil inner portion 90… case 91… fixing portion 92… bottom plate 100a, 100b… gap (first gap) 101… gap (second gap)

Claims

1. A bobbin, a first wire having a first coil portion wound around the bobbin, a second wire having a second coil portion wound around the bobbin, and a core attached to the bobbin, wherein the coil device the core has a base portion extending in a first axial direction, a main middle leg portion disposed substantially at the center of the base portion in the first axial direction, a first sub-middle leg portion disposed on one side of the main middle leg portion in the first axial direction in the base portion, and a second sub-middle leg portion disposed on the other side of the main middle leg portion in the first axial direction in the base portion, the main middle leg portion is disposed inside the first coil portion and the second coil portion, the first sub-middle leg portion is disposed inside the first coil portion and outside the second coil portion, the second sub-middle leg portion is disposed inside the second coil portion and outside the first coil portion, the core has a first core portion including at least a first base portion that is a part of the base portion, and a second core portion including at least a second base portion that is another part of the base portion and is substantially parallel to the first base portion, the first core portion and the second core portion sandwich the first coil portion and the second coil portion along the winding axis of the first coil portion, a first gap is formed in the first sub-middle leg portion, and a second gap is not provided in the main middle leg portion.

2. A bobbin, a first wire having a first coil portion wound around the bobbin, a second wire having a second coil portion wound around the bobbin, and a core attached to the bobbin, wherein the coil device the core has a base portion extending in a first axial direction, a main middle leg portion disposed substantially at the center of the base portion in the first axial direction, a first sub-middle leg portion disposed on one side of the main middle leg portion in the first axial direction in the base portion, and a second sub-middle leg portion disposed on the other side of the main middle leg portion in the first axial direction in the base portion, the main middle leg portion is disposed inside the first coil portion and the second coil portion, the first sub-middle leg portion is disposed inside the first coil portion and outside the second coil portion, the second sub-middle leg portion is disposed inside the second coil portion and outside the first coil portion, The core includes at least a first core portion including a first base portion that is a part of the base portion, and a second core portion including at least a second base portion that is another part of the base portion and is substantially parallel to the first base portion. The first core portion and the second core portion sandwich the first coil portion and the second coil portion along the winding axis of the first coil portion. No first gap is provided in the first sub-middle leg portion. A coil device in which a second gap is formed in the main middle leg portion.

3. A bobbin, A first wire having a first coil portion wound around the bobbin, A second wire having a second coil portion wound around the bobbin, A core attached to the bobbin, the coil device having: The core is A base portion extending in a first axial direction, A main middle leg portion disposed substantially at the center of the base portion in the first axial direction, A first sub-middle leg portion disposed on one side of the main middle leg portion in the first axial direction in the base portion, A second sub-middle leg portion disposed on the other side of the main middle leg portion in the first axial direction in the base portion, and The main middle leg portion is disposed inside the first coil portion and the second coil portion. The first sub-middle leg portion is disposed inside the first coil portion and outside the second coil portion. The second sub-middle leg portion is disposed inside the second coil portion and outside the first coil portion. The core includes at least a first core portion including a first base portion that is a part of the base portion, and a second core portion including at least a second base portion that is another part of the base portion and is substantially parallel to the first base portion. The first core portion and the second core portion sandwich the first coil portion and the second coil portion along the winding axis of the first coil portion. A first gap is formed in the first sub-middle leg portion. A second gap is formed in the main middle leg portion. A coil device in which the distances of the first gap and the second gap are determined to adjust leakage.

4. The core has a first outer leg portion and a second outer leg portion disposed on the base portion. The first sub-middle leg portion is disposed between the first outer leg portion and the main middle leg portion. The second sub-middle leg portion is disposed between the second outer leg portion and the main middle leg portion. The first outer leg portion is disposed outside the first coil portion. The coil device according to any one of claims 1 to 3, wherein the second outer leg portion is disposed outside the second coil portion.

5. The coil device according to claim 4, wherein the cross-sectional area of the main middle leg portion is substantially the same as the sum of the cross-sectional areas of the first outer leg portion and the second outer leg portion.

6. The coil device according to any one of claims 1 to 5, wherein the cross-sectional area of the main middle leg portion is larger than the cross-sectional area of the first sub-middle leg portion.

7. The coil device according to any one of claims 1 to 6, wherein the core is symmetric with respect to a symmetry axis orthogonal to the first axial direction.

8. The coil device according to any one of claims 1 to 7, wherein the first core portion and the second core portion are symmetric along the winding axis of the first coil portion.

9. The coil device according to any one of claims 1 to 8, wherein the core is divided along a second axis perpendicular to the first axis and the winding axis of the first coil portion.

10. The bobbin has a first winding portion around which the first coil portion is wound, a second winding portion around which the second coil portion is wound, and a winding partition flange that separates the first winding portion and the second winding portion. In the first winding portion, a first main through-hole in which the main middle leg portion is disposed and a first sub-through-hole in which the first sub-middle leg portion is disposed are formed. In the second winding portion, a second main through-hole in which the main middle leg portion is disposed and a second sub-through-hole in which the second sub-middle leg portion is disposed are formed. The coil device according to any one of claims 1 to 9, wherein the first main through-hole and the second main through-hole communicate with each other.

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