Coil device

Abstract

To provide a coil device capable of preventing a core from being damaged.SOLUTION: The coil device 1 includes a main core 10 and an auxiliary core 20. The main core 10 includes a first winding core portion 11 around which the first coil 31 is wound, a second winding core portion 12 that is disposed substantially parallel to the first winding core portion 11 and around which the second coil 32 is wound, a first flange portion 13 to which one end of the first winding core portion 11 in the axial direction and one end of the second winding core portion 12 in the axial direction are connected, and a second flange portion 14 to which the other end of the first winding core portion 11 in the axial direction and the other end of the second winding core portion 12 in the axial direction are connected. The auxiliary core 20 is fixed to the main core 10 on the side opposite to the mounting surface so as to straddle the first flange part 13 and the second flange part 14.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a coil device that is suitable for use as a filter or the like. [Background technology]

[0002] In recent years, various technologies related to coil devices have been proposed. Among various coil devices used as filters and the like, there is one that has an annular core, as shown in Patent Document 1. In the coil device shown in Patent Document 1, a first coil and a second coil can be wound around a first winding core and a second winding core, respectively. In addition, the coil device can be mounted on a mounting board via a plurality of terminal electrodes provided on the first flange and the second flange.

[0003] However, external forces may be applied to the mounting substrate due to various factors, which may cause the mounting substrate to twist. In this case, stress caused by the twist of the mounting substrate acts on the coil device mounted on the mounting substrate, which may cause a problem of core damage, particularly near the boundaries between each winding core portion and each flange portion. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-004874 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a coil device capable of preventing damage to the core. [Means for solving the problem]

[0006] In order to achieve the above object, a coil device according to the present invention comprises: a first winding core around which the first coil is wound; a second winding core portion disposed substantially parallel to the first winding core portion and around which a second coil is wound; a first flange portion at which one axial end of the first winding core portion and one axial end of the second winding core portion are connected; a main core including a second flange portion that connects the other axial end of the first winding core portion and the other axial end of the second winding core portion; The rotor further includes an auxiliary core fixed to the main core on the side opposite to the mounting surface so as to straddle the first flange and the second flange.

[0007] In the coil device according to the present invention, the auxiliary core can be fixed to the main core on the side opposite the mounting surface so as to straddle the first flange and the second flange. By fixing the auxiliary core to the main core in this manner, even if stress acts on the main core due to twisting of the mounting board or the like, the stress can be dispersed to the auxiliary core. In other words, the stress acting on the main core can be absorbed by the auxiliary core, preventing stress concentration on the main core. As a result, the stress acting on the main core is reduced, particularly near the boundaries between each winding core portion and each flange, effectively preventing damage to the main core.

[0008] The auxiliary core may have a main body having a rectangular parallelepiped shape and first and second outer legs formed on the main body at a predetermined interval and extending substantially parallel to each other. The first outer leg may be fixed to the first and second flanges along the first winding core so as to straddle the first and second flanges, and the second outer leg may be fixed to the first and second flanges along the second winding core so as to straddle the first and second flanges. With this configuration, when stress occurs in the main core due to torsion of the mounting board or the like, the stress is transmitted from the main core to the auxiliary core via the first and second outer legs. Therefore, even with the above configuration, stress generated in the main core can be dispersed to the auxiliary core, effectively preventing damage to the main core.

[0009] In addition, by forming the first outer leg and the second outer leg on the auxiliary core, when the auxiliary core is fixed to the first flange and the second flange, it is possible to form a gap between the main body and the first flange and between the main body and the second flange. For example, by connecting the lead of the first coil or the lead of the second coil to a terminal electrode inside such a gap, it is possible to save space in the coil device and thereby make the coil device smaller and thinner.

[0010] Preferably, the auxiliary core has a center leg formed on the main body portion and extending between the first outer leg portion and the second outer leg portion and generally parallel to the first outer leg portion and the second outer leg portion, and the center leg portion is fixed to the first flange portion and the second flange portion between the first winding core portion and the second winding core portion so as to straddle the first flange portion and the second flange portion. With this configuration, when stress occurs in the main core due to torsion of the mounting board or the like, the stress is transmitted from the main core to the auxiliary core not only through the first outer leg portion and the second outer leg portion but also through the center leg portion. This improves the auxiliary core's ability to disperse (absorb) stress, effectively preventing damage to the main core.

[0011] Preferably, the coil further comprises a first terminal electrode provided on the first flange and connected to one lead portion of the first coil, a second terminal electrode provided on the first flange and connected to one lead portion of the second coil, a third terminal electrode provided on the second flange and connected to the other lead portion of the first coil, and a fourth terminal electrode provided on the second flange and connected to the other lead portion of the second coil, wherein the first terminal electrode and the third terminal electrode are located between the first outer leg and the center leg, and the second terminal electrode and the fourth terminal electrode are located between the second outer leg and the center leg.

[0012] With this configuration, one lead portion of the first coil can be connected to the first terminal electrode and one lead portion of the second coil can be connected to the second terminal electrode by utilizing the gap between the main body and the first flange. Similarly, the other lead portion of the first coil can be connected to the third terminal electrode and the other lead portion of the second coil can be connected to the fourth terminal electrode by utilizing the gap between the main body and the second flange. This eliminates the need to secure additional space for connecting each lead portion to each terminal electrode, thereby enabling the coil device to be made smaller and thinner. Furthermore, since center legs are disposed between the lead portions of the first coil and the lead portions of the second coil, these lead portions can be effectively insulated via the center legs.

[0013] The auxiliary core may have a main body having a rectangular parallelepiped shape, a first leg formed at a first corner of the main body, a second leg formed at a second corner of the main body, a third leg formed at a third corner of the main body, and a fourth leg formed at a fourth corner of the main body, the first leg and the second leg being fixed to the first flange at a predetermined interval, and the third leg and the fourth leg being fixed to the second flange at a predetermined interval. In this way, by forming the first to fourth legs locally (spot-wise) at the four corners of the main body, it is possible to prevent the first coil and the second coil from interfering with the first to fourth legs when the auxiliary core is fixed to the main core.

[0014] The auxiliary core may have a main body portion having a rectangular parallelepiped shape, with one end of the main body portion abutting against the surface opposite the mounting surface of the first flange portion and the other end of the main body portion abutting against the surface opposite the mounting surface of the second flange portion. With this configuration, the main body portion directly abuts against the surfaces of the first flange portion and the second flange portion, allowing the auxiliary core to contact the main core over a relatively large contact area. Therefore, when stress occurs in the main core due to twisting of the mounting board, for example, the stress can be efficiently transmitted from the main core to the auxiliary core, effectively enhancing the auxiliary core's ability to dissipate (absorb) the stress.

[0015] The auxiliary core may have a main body portion having a rectangular parallelepiped shape and first and second outer legs formed on the main body portion at a predetermined interval and extending substantially parallel to each other, the first outer leg abutting against a surface opposite the mounting surface of the first flange, and the second outer leg abutting against a surface opposite the mounting surface of the second flange, the opposing direction of the first outer leg and the second outer leg substantially matching the opposing direction of the first flange and the second flange. This configuration allows a large portion of the first outer leg to abut against the surface of the first flange, ensuring a sufficient contact area therebetween and enhancing the integrity of the first outer leg and the first flange. Furthermore, a large portion of the second outer leg can abut against the surface of the second flange, ensuring a sufficient contact area therebetween and enhancing the integrity of the second outer leg and the second flange. As a result, the ability of the auxiliary core to disperse (absorb) stress can be effectively improved.

[0016] Preferably, the coil assembly further comprises a first terminal electrode provided on the first flange and connected to one lead portion of the first coil, a second terminal electrode provided on the first flange and connected to one lead portion of the second coil, a third terminal electrode provided on the second flange and connected to the other lead portion of the first coil, and a fourth terminal electrode provided on the second flange and connected to the other lead portion of the second coil, wherein one lead portion of the first coil is connected to the first terminal electrode on the mounting surface of the first flange, one lead portion of the second coil is connected to the second terminal electrode on the mounting surface of the first flange, the other lead portion of the first coil is connected to the third terminal electrode on the mounting surface of the second flange, and the other lead portion of the second coil is connected to the fourth terminal electrode on the mounting surface of the second flange. With this configuration, the auxiliary core can be fixed to the surface of the first flange opposite the mounting surface and the surface of the second flange opposite the mounting surface without being obstructed by the lead portions.

[0017] Preferably, the auxiliary core is made of a non-magnetic material. With this configuration, when the auxiliary core is fixed to the main core, it is possible to prevent the magnetic fields generated by the first coil and the second coil from passing through the auxiliary core. Therefore, particularly when the coil device according to the present invention is used as a common mode filter, it is possible to prevent the performance from being affected. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a perspective view of a coil device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view of a main core of the coil device shown in FIG. [Figure 3] FIG. 3 is a cross-sectional view of the coil device shown in FIG. 1 taken along line III-III. [Figure 4] FIG. 4 is a perspective view of the coil device shown in FIG. 1 with an auxiliary core removed. [Figure 5] FIG. 5 is a perspective view of a terminal electrode of the coil device shown in FIG. [Figure 6] 6 is a perspective view of an auxiliary core of the coil device shown in FIG. [Figure 7] FIG. 7 is a perspective view of a coil device according to a second embodiment of the present invention. [Figure 8] FIG. 8 is a perspective view of the main core of the coil device shown in FIG. [Figure 9] FIG. 9 is a cross-sectional view taken along line IX-IX of the coil device shown in FIG. [Figure 10] FIG. 10 is a side view of the coil device shown in FIG. [Figure 11A] FIG. 11A is a diagram showing the results of a simulation of the distribution of stress applied to the main core of the coil device shown in FIG. [Figure 11B] FIG. 11B is a view of the main core shown in FIG. 11A as seen from the opposite side to the mounting surface. [Figure 12A] FIG. 12A is a diagram showing the results of a simulation of the distribution of stress applied to the main core of a conventional coil device. [Figure 12B] FIG. 12B is a view of the main core shown in FIG. 12A as seen from the opposite side to the mounting surface. [Figure 13] FIG. 13 is a diagram showing the conditions of the simulation. [Figure 14] FIG. 14 is a perspective view of a coil device according to a third embodiment of the present invention. [Figure 15] 15 is a perspective view of an auxiliary core of the coil device shown in FIG. [Figure 16] FIG. 16 is a perspective view of a coil device according to a fourth embodiment of the present invention. [Figure 17] FIG. 17 is a perspective view of an auxiliary core of a coil device according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, the present invention will be described based on the embodiments shown in the drawings.

[0020] First embodiment 1 functions as various filters such as a common mode filter or a common mode choke coil, and is mounted in the power supply circuits of EVs (Electric Vehicles) and household or industrial electrical equipment. The size of the coil device 1 is not particularly limited, but the width of the coil device 1 in the X-axis direction is preferably 1.0 to 10 mm, the width of the coil device 1 in the Y-axis direction is preferably 1.0 to 10 mm, and the width of the coil device 1 in the Z-axis direction is preferably 0.5 to 8.0 mm.

[0021] In the following description, the positive Z-axis direction is referred to as the upper side, and the negative Z-axis direction is referred to as the lower side. The Z-axis direction corresponds to the thickness direction of the coil device 1, and the Y-axis direction corresponds to the width direction of the coil device 1. The side toward the center of the coil device 1 is referred to as the inside, and the side away from the center of the coil device 1 is referred to as the outside. The mounting surface of the coil device 1 is the lower surface of the coil device 1.

[0022] The coil device 1 has a main core 10 and an auxiliary core 20. In addition to these components, the coil device 1 also has a first coil 31, a second coil 32, and terminal electrodes 41 to 44 (see FIG. 4).

[0023] 2, the main core 10 is annular and has a first winding core portion 11, a second winding core portion 12, a first flange portion 13, and a fourth flange portion 14. These members are integrally connected so that a central hole 15 is formed inside.

[0024] The main core 10 is formed from a material containing a magnetic material and a resin. Examples of the magnetic material forming the main core 10 include ferrite particles or metal magnetic particles. Examples of ferrite particles include Ni-Zn ferrite and Mn-Zn ferrite. Examples of the metal magnetic particles include, but are not limited to, Fe-Ni alloy powder, Fe-Si alloy powder, Fe-Si-Cr alloy powder, Fe-Co alloy powder, Fe-Si-Al alloy powder, and amorphous iron. Examples of the resin forming the core 20 include, but are not limited to, epoxy resin, phenolic resin, polyester resin, polyurethane resin, polyimide resin, other synthetic resins, and other non-magnetic materials. The main core 10 may also be a sintered metal magnetic body.

[0025] First flange 13 has a generally rectangular parallelepiped shape with its longitudinal direction in the Y-axis direction. Outer recesses 131 and 132 are formed on outer end surface 13c of first flange 13. Outer recesses 131 and 132 are each recessed to a predetermined depth in the X-axis direction and extend at a constant width along outer end surface 13c from upper surface 13a to lower surface 13b of first flange 13.

[0026] The outer recess 131 is formed on the negative side of the outer end surface 13c in the Y-axis direction, and the outer recess 132 is formed on the positive side of the outer end surface 13c in the Y-axis direction. The outer recess 131 and the outer recess 132 are formed at a predetermined interval in the Y-axis direction, and terminal electrodes 41 and 42 ( FIG. 4 ) can be installed in the outer recesses 131 and 132, respectively. When the outer recesses 131 and 132 are formed on the outer end surface 13c in this manner, when the terminal electrodes 41 and 42 are installed on the first flange 13, the surfaces of the terminal electrodes 41 and 42 and the outer end surface 13c of the first flange 13 are approximately flush with each other. This prevents the terminal electrodes 41 and 42 from unnecessarily protruding outward in the X-axis direction from the outer end surface 13c of the first flange 13.

[0027] Steps 133 and 134 are formed on the lower surface 13b of the first flange 13. Step 133 is formed at the end of the lower surface 13b on the negative Y-axis direction side. Step 134 is formed at the end of the lower surface 13b on the positive Y-axis direction side. The lower surface 13b of the first flange 13, together with the lower surface 14b of the second flange 14, constitutes the mounting surface of the coil device 1.

[0028] By forming step portion 133 on lower surface 13b, the thickness of the end portion on the negative Y-axis direction of first flange portion 13 is smaller than the thickness of the central portion of first flange portion 13 in the Y-axis direction. Furthermore, by forming step portion 134 on lower surface 13b, the thickness of the end portion on the positive Y-axis direction of first flange portion 13 is smaller than the thickness of the central portion of first flange portion 13 in the Y-axis direction. Therefore, by forming step portions 133 and 134 on first flange portion 13, it is possible to reduce the size and weight of first flange portion 13. Furthermore, when coil device 1 is mounted on a mounting board, it is possible to prevent each end portion in the Y-axis direction of lower surface 13b of first flange portion 13 from contacting the mounting board.

[0029] Step portion 133 has tapered portion 133a, and step portion 134 has tapered portion 134a. Tapered portions 133a and 134a are each inclined upward as they extend outward in the Y-axis direction. The inclination angles of tapered portions 133a and 133b are preferably determined taking into consideration the contact area between terminal electrode 41 and lower surface 13b of first flange portion 13, or the contact area between terminal electrode 42 and lower surface 13b of first flange portion 13, as shown in FIG.

[0030] That is, since tapered portion 133a extends to the contact portion between terminal electrode 41 and lower surface 13b, it is preferable to determine the inclination angle of tapered portion 133a so that the contact area (contact length along the Y-axis direction) of the contact portion can be appropriately secured. Also, since tapered portion 134a extends to the contact portion between terminal electrode 42 and lower surface 13b, it is preferable to determine the inclination angle of tapered portion 134a so that the contact area (contact length along the Y-axis direction) of the contact portion can be appropriately secured.

[0031] From the viewpoint of ensuring stability when terminal electrode 41 is attached to first flange portion 13, it is preferable that at least half of the width in the Y-axis direction of terminal electrode 41 abuts against lower surface 13b. Similarly, it is preferable that at least half of the width in the Y-axis direction of terminal electrode 42 abuts against lower surface 13b.

[0032] 2, an inner recess 15 is formed on the inner end surface 13d of the first flange portion 13. The inner recess 15 is a recess that is recessed to a predetermined depth in the X-axis direction, and is formed in the center of the inner end surface 13d in the Y-axis direction (a position between the first winding core portion 11 and the second winding core portion 12). By forming the inner recess 15 on the inner end surface 13d in this way, it is possible to reduce the size and weight of the first flange portion 13, and also to adjust the magnetic characteristics of the coil device 1.

[0033] Second flange 14 is disposed opposite first flange 13 along the X-axis direction. Second flange 14 is disposed parallel to first flange 13 (the longitudinal direction of second flange 14 coincides with the longitudinal direction of first flange 13). Since second flange 14 has a similar shape to first flange 13, detailed description of second flange 14 will be omitted. Terminal electrode 43 (FIG. 4) is disposed in outer recess 141 of second flange 14, and terminal electrode 44 (FIG. 4) is disposed in outer recess 142.

[0034] The first winding core 11 has a columnar shape (approximately rectangular parallelepiped shape), and the axial direction of the first winding core 11 coincides with the X-axis direction. The width of the first winding core 11 in the Y-axis direction is smaller than half the length of the width of the first flange 13 in the Y-axis direction. A first coil 31 (FIG. 4) is wound around the first winding core 11. As shown in FIG. 4, the first coil 31 is formed of a round wire, such as a copper wire covered with an insulating coating. The wire (first wire) forming the first coil 31 is not limited to a round wire and may be a square wire or a Litz wire. The first coil 31 is formed in one layer in the radial direction, but may be formed in two or more layers. The same applies to the second coil 32 and the wire (second wire) forming it.

[0035] As shown in Figure 2, one axial end of the first winding core portion 11 is connected to the inner end surface 13d of the first flange portion 13, and the other axial end of the first winding core portion 11 is connected to the inner end surface 14d of the second flange portion 14.

[0036] An upward tapered portion 110 is formed on the upper surface of one axial end portion of the first winding core 11. Similarly, an upward tapered portion 110 is formed on the upper surface of the other axial end portion of the first winding core 11.

[0037] By forming an upward tapered portion 110 at one axial end of the first winding core portion 11, the upper surface of the first winding core portion 11 and the upper surface 13a of the first flange portion 13 are smoothly connected. Furthermore, by forming an upward tapered portion 110 at the other axial end of the first winding core portion 11, the upper surface of the first winding core portion 11 and the upper surface 14a of the second flange portion 14 are smoothly connected. Therefore, as shown in FIG. 4 , the lead portion 31a of the first coil 31 can be drawn from the first winding core portion 11 toward the first flange portion 13 along the surface of the main core 10, and the lead portion 31b of the first coil 31 can be drawn from the first winding core portion 11 toward the second flange portion 14 along the surface of the main core 10.

[0038] As shown in FIG. 2, the second winding core 12 has a similar shape to the first winding core 11 and is disposed approximately parallel to the first winding core 11. The width of the second winding core 12 in the Y-axis direction is smaller than half the length of the width of the first flange 13 in the Y-axis direction. A second coil 32 (FIG. 4) is wound around the second winding core 12. One axial end of the second winding core 12 is connected to the inner end surface 13d of the first flange 13, and the other axial end of the second winding core 12 is connected to the inner end surface 14d of the second flange 14.

[0039] An upward tapered portion 120 is formed on the upper surface of one axial end portion of the second winding core portion 12. Similarly, an upward tapered portion 120 is formed on the upper surface of the other axial end portion of the second winding core portion 12. The upward tapered portion 120 has the same function as the upward tapered portion 110, and enables the lead portion 32a (or lead portion 32b) of the second coil 32 to be drawn from the second winding core portion 12 toward the first flange portion 13 (or second flange portion 14) along the surface of the main core 10.

[0040] The first winding core 11 is connected at a relatively high position to the inner end surface 13d of the first flange 13 and the inner end surface 14d of the second flange 14. Therefore, the upper part of the first winding core 11 protrudes above the upper surface 13a of the first flange 13 and the upper surface 14a of the second flange 14. The same is true for the second winding core 12.

[0041] In this way, by arranging the first winding core portion 11 and the second winding core portion 12 relatively higher, it is possible to arrange the first coil 31 and the second coil 32 at a position sufficiently above the lower surface 13b (mounting surface) of the first flange portion 13, as shown in Fig. 3. Therefore, even if the number of turns of the first coil 31 and the second coil 32 is increased, it is possible to prevent problems such as the first coil 31 and the second coil 32 coming into contact with the mounting board.

[0042] 5, the terminal electrodes 41 to 44 are formed of conductive terminals such as metal, and are configured to be attachable to the first flange 13 or the second flange 14 (FIG. 2). Note that the terminal electrodes 41 to 44 may also be formed by forming a conductive member such as a plating film on the first flange 13 or the second flange 14.

[0043] The terminal electrode 41 has a generally C-shape overall and includes a mounting portion 410, a connecting portion 411, a linking portion 412, and a pair of clamping portions 413a and 413b. The mounting portion 410 has a surface that is generally parallel to the lower surface 13b of the first flange portion 13 (FIG. 4), and extends inward in the X-axis direction. The mounting portion 410 is fixed to the lower surface 13b of the first flange portion 13. Note that, as shown in FIG. 3, a portion of the mounting portion 410, at the position of the tapered portion 133a, does not come into contact with the lower surface 13b.

[0044] As shown in FIG. 5, the connecting portion 411 has a surface that is approximately parallel to the upper surface 13a of the first flange 13 (FIG. 4) and extends inward in the X-axis direction. The mounting portion 410 is fixed to the upper surface 13a of the first flange 13. The clamping portions 413a and 413b are connected to the respective ends of the connecting portion 411 in the Y-axis direction and extend upward. The clamping portions 413a and 413b are bent in directions that approach each other, allowing them to clamp the lead portion 31a of the first coil 31. The tip ends of the clamping portions 413a and 413b are bent so as to be approximately parallel to the XY plane.

[0045] The connecting portion 412 connects the mounting portion 410 and the connecting portion 411. The connecting portion 412 has a surface that is approximately parallel to the outer end surface 13c (FIG. 4) of the first flange portion 13, and extends along the Z-axis direction. The connecting portion 412 is fixed to the outer end surface 13c of the first flange portion 13.

[0046] 4, the terminal electrode 41 is fixed to the first flange 13 so that the upper surface 13a and the lower surface 13b of the first flange 13 are sandwiched between the mounting portion 410 and the connecting portion 411. The terminal electrode 41 is firmly fixed to the first flange 13 by an adhesive or the like.

[0047] 5, terminal electrode 42 has a mounting portion 420, a connecting portion 421, a linking portion 422, and a pair of clamping portions 423a and 423b. Terminal electrode 42 is disposed at a predetermined distance in the Y-axis direction relative to terminal electrode 41. The configuration of terminal electrode 42 is the same as the configuration of terminal electrode 41, and therefore a detailed description thereof will be omitted. Note that clamping portions 423a and 423b clamp lead portion 32a (FIG. 4) of second coil 32.

[0048] The terminal electrode 43 has a mounting portion 430, a connecting portion 431, a linking portion 432, and a pair of clamping portions 433a and 433b. The configuration of the terminal electrode 43 is the same as the configuration of the terminal electrode 41, so a detailed description thereof will be omitted. The clamping portions 433a and 433b clamp the lead portion 31b (FIG. 4) of the first coil 31. The terminal electrode 43 is firmly fixed to the second flange portion 14 by an adhesive or the like.

[0049] The terminal electrode 44 has a mounting portion 440, a connecting portion 441, a linking portion 442, and a pair of clamping portions 443a and 443b. The terminal electrode 44 is disposed at a predetermined distance in the Y-axis direction relative to the terminal electrode 43. The configuration of the terminal electrode 44 is the same as the configuration of the terminal electrode 43, and therefore a detailed description thereof will be omitted. The clamping portions 443a and 443b clamp the lead portion 32b of the second coil 32.

[0050] 4, lead portions 31a and 31b of first coil 31 are firmly connected to terminal electrodes 41 and 43, respectively, by connecting members 50 made of solder, conductive adhesive, etc. Furthermore, lead portions 32a and 32b of second coil 32 are firmly connected to terminal electrodes 42 and 44, respectively, by connecting members 50 made of solder, conductive adhesive, etc.

[0051] As shown in FIG. 6, the auxiliary core 20 is an E-shaped core and has a main body 21, a first outer leg 22a, a second outer leg 22b, and a center leg 23. The main body 21 has a rectangular parallelepiped shape. The widths of the main body 21 in the X-axis direction and the Y-axis direction are approximately the same as the widths of the main core 10 (FIG. 2) in the X-axis direction and the Y-axis direction, but may be larger. The main body 21 is disposed above the first winding core 11 and the second winding core 12 so as to cover the central hole 15 (FIG. 1) of the main core 10.

[0052] The first outer leg 22a and the second outer leg 22b are formed at a predetermined interval in the Y-axis direction on the lower surface of the main body 21 (the surface on which the main core 10 is disposed). The first outer leg 22a and the second outer leg 22b protrude downward toward where the main core 10 is located. The first outer leg 22a and the second outer leg 22b extend substantially parallel to each other along the X-axis direction from one end to the other end of the main body 21 in the X-axis direction. The first outer leg 22a and the second outer leg 22b do not necessarily have to be formed at the ends of the main body 21 in the Y-axis direction, but may be formed at positions spaced a predetermined distance inward in the Y-axis direction from one end and the other end of the main body 21 in the Y-axis direction, respectively.

[0053] The center leg 23 is formed on the underside of the main body 21 and is located between the first outer leg 22a and the second outer leg 22b in the Y-axis direction (the center of the main body 21 in the Y-axis direction). The center leg 23 protrudes downward toward where the main core 10 is located. The center leg 23 extends along the X-axis direction substantially parallel to the first outer leg 22a and the second outer leg 22b.

[0054] As shown in Fig. 1, the auxiliary core 20 is fixed to the main core 10 on the side opposite the mounting surface so as to straddle the first flange 13 and the second flange 14. More specifically, as shown in Figs. 1 and 2, the first outer leg 22a is fixed to the first flange 13 and the second flange 14 along the first winding core 11 so as to straddle the first flange 13 and the second flange 14. Furthermore, the second outer leg 22b is fixed to the first flange 13 and the second flange 14 along the second winding core 12 so as to straddle the first flange 13 and the second flange 14. In addition, the center leg portion 23 is fixed to the first flange portion 13 and the second flange portion 14 between the first winding core portion 11 and the second winding core portion 12 (above the central hole 15) so as to straddle the first flange portion 13 and the second flange portion 14.

[0055] 3, the first outer leg portion 22a is fixed to the first flange portion 13 (and the first flange portion 14) on the outer side in the Y-axis direction of the first winding core portion 11. The second outer leg portion 22b is fixed to the first flange portion 13 (and the first flange portion 14) on the outer side in the Y-axis direction of the second winding core portion 12.

[0056] The first outer leg 22a, the second outer leg 22b, and the center leg 23 are firmly connected to the upper surface 13a of the first flange 13 and the upper surface 14a of the second flange 14 with an adhesive or the like. To ensure sufficient connection strength between them and to prevent the auxiliary core 20 from coming off the main core 10, the resin used to bond them is preferably an epoxy resin. When the auxiliary core 20 is fixed to the main core 10 with such a resin, the auxiliary core 20 is attached to the main core 10 in an undetachable manner.

[0057] When the auxiliary core 20 is fixed to the main core 10, as shown in FIG. 3, gaps G1 and G2 are formed between the main body 21 and the first flange 13 (and between the main body 21 and the second flange 14). The heights of the gaps G1 and G2 correspond to the lengths of the first outer leg 22a and other components in the Z-axis direction. The upper portions of the first winding core 11 and the first coil 31 are disposed in the gap G1. The upper portions of the second winding core 12 and the second coil 32 are disposed in the gap G2. The gaps G1 and G2 have appropriate heights, which prevents the upper portions of the first coil 31 and the second coil 32 from interfering with the underside of the main body 21. It is preferable to appropriately adjust the number of layers of the first coil 31 in the radial direction within a range that allows the upper portion of the first coil 31 to fit into the gap G1. Furthermore, it is preferable to adjust the number of layers of the second coil 32 in the radial direction as appropriate within a range that allows the upper portion of the second coil 32 to fit into the gap G2.

[0058] As shown in FIG. 1, when the auxiliary core 20 is fixed to the main core 10, the terminal electrode 41 (connection portion 411) is located in the gap G1 between the first outer leg 22a and the center leg 23. Although not shown in detail, the same applies to the terminal electrode 43 (connection portion 431). Furthermore, the terminal electrode 42 (connection portion 421) is located in the gap G2 between the second outer leg 22b and the center leg 23. Although not shown in detail, the same applies to the terminal electrode 44 (connection portion 441).

[0059] Furthermore, a connecting member 50 is disposed in the gap G1 to reinforce the connection between the lead portion 31a (FIG. 4) of the first coil 31 and the terminal electrode 41. Although not shown in detail, a connecting member 50 is disposed in the gap G1 on the negative X-axis side of the coil device 1 to reinforce the connection between the lead portion 31b (FIG. 4) of the first coil 31 and the terminal electrode 43. Furthermore, a connecting member 50 is disposed in the gap G2 to reinforce the connection between the lead portion 32a (FIG. 4) of the second coil 32 and the terminal electrode 42. Although not shown in detail, a connecting member 50 is disposed in the gap G2 on the negative X-axis side of the coil device 1 to reinforce the connection between the lead portion 32b (FIG. 4) of the second coil 32 and the terminal electrode 44.

[0060] In this way, by connecting the lead portions 31a and 31b of the first coil 31 to the terminal electrodes 41 and 43, respectively, inside the gap G1, it is possible to reduce the space required for the coil device 1. Furthermore, by connecting the lead portions 32a and 32b of the second coil 32 to the terminal electrodes 42 and 44, respectively, inside the gap G2, it is possible to reduce the space required for the coil device 1.

[0061] Furthermore, there is no need to secure additional space for connecting the lead portions 31a and the like to the terminal electrodes 41 and the like, and the above connections can be made by utilizing the gaps G1 and G2 that are inevitably formed between the main body 21 and the first flange 13 and the second flange 14, respectively, thereby making it possible to reduce the size and height of the coil device 1. Furthermore, since the center leg 23 is disposed between the lead portions 31a and 32a (FIG. 4), the center leg 23 can effectively insulate the lead portions 31a and 32a from each other. Similarly, the center leg 23 can effectively insulate the lead portions 31b and 32b from each other.

[0062] In this embodiment, the auxiliary core 20 has the function of absorbing stress acting on the main core 10. That is, by fixing the auxiliary core 20 to the main core 10 in the manner shown in Fig. 1, when stress acts on the main core 10 due to twisting of the mounting board or the like, the stress can be dispersed to the auxiliary core 20, preventing the stress from concentrating on the main core 10.

[0063] From the viewpoint of enhancing the effect of dispersing stress from the main core 10 to the auxiliary core 20, the auxiliary core 20 is preferably formed of a material harder than, for example, plastic. The auxiliary core 20 is also preferably formed of a material harder than the main core 10. In other words, the rigidity (Young's modulus) of the auxiliary core 20 is preferably higher than the rigidity (Young's modulus) of the main core 10. The longitudinal modulus of elasticity of the auxiliary core 20 is preferably 1.0×10 5 N / mm 2 ~2.0×10 5 N / mm 2is.

[0064] Furthermore, the yield strength of the auxiliary core 20 is preferably greater than the yield strength of the main core 10. The yield strength of the auxiliary core 20 is preferably 250 N / mm 2 ~400N / mm 2 is.

[0065] Furthermore, from the viewpoint of enhancing the effect of dispersing stress from main core 10 to auxiliary core 20, it is preferable that auxiliary core 20 be relatively thick. The thickness of auxiliary core 20 is preferably 0.7 mm or more, and more preferably 1.0 mm or more.

[0066] 3, for example, the thickness of main body 21 in the Z-axis direction is preferably greater than the lengths in the Z-axis direction of first outer leg 22a, second outer leg 22b, and center leg 23. The thickness of main body 21 in the Z-axis direction is preferably greater than the thicknesses in the Z-axis direction of first winding core 11 and second winding core 12, and is further preferably greater than the thicknesses in the Z-axis direction (maximum thicknesses) of first flange 13 and second flange 14.

[0067] In addition, from the viewpoint of enhancing the effect of dispersing stress from the main core 10 to the auxiliary core 20, it is preferable that the contact area between the auxiliary core 20 and the main core 10 is relatively large. In FIG. 3, the width W1 in the Y-axis direction of the first outer leg 22a is smaller than the length L1 between the end of the first winding core 11 on the positive side of the Y-axis and the end of the first flange 13 on the positive side of the Y-axis, but it may be approximately the same. In addition, the width W1 in the Y-axis direction of the second outer leg 22b is smaller than the length L1 between the end of the second winding core 12 on the negative side of the Y-axis and the end of the first flange 13 on the negative side of the Y-axis, but it may be approximately the same. In addition, the width W2 in the Y-axis direction of the center leg 23 is smaller than the length L2 between the first winding core 11 and the second winding core 12, but it may be approximately the same. With this configuration, the contact area between the auxiliary core 20 and the main core 10 can be relatively large. In this embodiment, W2>W1, but W2=W1 may also be satisfied. <W1でもよい。

[0068] Furthermore, the width W1 in the Y-axis direction of first outer leg 22a may be approximately the same as the length L3 between the end of terminal electrode 41 on the negative side of the Y-axis and the end of first flange 13 on the negative side of the Y-axis, as shown in FIG. 4. The width W1 in the Y-axis direction of second outer leg 22b may be approximately the same as the length L3 between the end of terminal electrode 42 on the positive side of the Y-axis and the end of first flange 13 on the positive side of the Y-axis, as shown in FIG. 4. The width W2 in the Y-axis direction of center leg 23 may be approximately the same as the length L4 between terminal electrode 41 and terminal electrode 42. With this configuration, the contact area between auxiliary core 20 and main core 10 can be relatively increased.

[0069] In addition, by adhesively fixing the auxiliary core 20 to the main core 10 with an epoxy-based resin at all contact points between the auxiliary core 20 and the main core 10, the auxiliary core 20 and the main core 10 are integrally connected, thereby improving the effect of dispersing stress from the main core 10 to the auxiliary core 20.

[0070] The auxiliary core 20 is made of a material different from that of the main core 10. The auxiliary core 20 is preferably made of a non-magnetic material. Examples of non-magnetic materials that can be used to form the auxiliary core 20 include ceramics. By making the auxiliary core 20 of a non-magnetic material in this way, when the auxiliary core 20 is fixed to the main core 10 as shown in FIG. 1, it is possible to prevent the magnetic fields generated by the first coil 31 and the second coil 32 from passing through the inside of the auxiliary core 20 (i.e., to prevent the magnetic characteristics of the coil device 1 from changing). This prevents the performance of the coil device 1 from being affected when it is used as a common mode filter.

[0071] Next, a method for manufacturing the coil device 1 will be described. First, the components shown in FIG. 1 are prepared. Terminal electrodes 41 to 44 shown in FIG. 5 are attached to the main core 10 in the manner shown in FIG. 4. At this time, if necessary, the fixation of the terminal electrodes 41 to 44 to the main core 10 is reinforced with an adhesive (for example, an epoxy resin). Next, as shown in FIG. 4, the first coil 31 is wound around the first winding core 11, and the second coil 32 is wound around the second winding core 12.

[0072] Next, the lead portion 31a of the first coil 31 is sandwiched between the clamping portions 413a and 413b of the terminal electrode 41 and temporarily fixed. The lead portion 31b of the first coil 31 is sandwiched between the clamping portions 433a and 433b of the terminal electrode 43 and temporarily fixed. The lead portion 32a of the second coil 32 is sandwiched between the clamping portions 423a and 423b of the terminal electrode 42 and temporarily fixed. The lead portion 32b of the second coil 32 is sandwiched between the clamping portions 443a and 443b of the terminal electrode 44 and temporarily fixed.

[0073] Next, the lead portion 31a temporarily fixed to the terminal electrode 41 is connected with a connecting member 50. The connecting member 50 can be formed by various techniques, such as applying solder or a conductive adhesive, or laser welding. Similarly, the lead portion 31b temporarily fixed to the terminal electrode 43 is connected with the connecting member 50, the lead portion 32a temporarily fixed to the terminal electrode 42 is connected with the connecting member 50, and the lead portion 32b temporarily fixed to the terminal electrode 44 is connected with the connecting member 50.

[0074] Next, the auxiliary core 20 shown in Fig. 6 is fixed to the main core 10 shown in Fig. 4. Specifically, as shown in Fig. 1, the first outer leg 22a, the second outer leg 22b, and the center leg 23 of the auxiliary core 20 are adhered and fixed with an adhesive or the like to the surface of the main core 10 opposite the mounting surface (the upper surface 13a of the first flange 13 and the upper surface 14a of the second flange 14) so ​​as to connect the first flange 13 and the second flange 14 via the main body 21 (forming a bridge between the first flange 13 and the second flange 14). In this manner, the coil device 1 can be manufactured.

[0075] 1 due to twisting of the mounting board or the like, the stress is transmitted from the main core 10 to the auxiliary core 20 via the first outer leg 22a, the second outer leg 22b, and the center leg 23. This makes it possible to distribute the stress generated in the main core 10 to the auxiliary core 20, and reduces the stress applied to the main core 10 particularly near the boundaries between the winding core portions (first winding core portion 11 and second winding core portion 12) and the flange portions (first flange portion 13 and second flange portion 14), effectively preventing damage to the main core 10.

[0076] Second embodiment A coil device 1A according to a second embodiment of the present invention shown in Fig. 7 has the same configuration as the coil device 1 according to the first embodiment, except for the following points: In Fig. 7, members that overlap with those of the coil device 1 according to the first embodiment are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0077] As shown in Fig. 7, the coil device 1A has a main core 10A, an auxiliary core 20A, and terminal electrodes 41A to 44A. As shown in Fig. 8, the main core 10A has a first winding core portion 11A and a second winding core portion 12A. As is clear from comparing Fig. 8 with Fig. 2, one end of each of the first winding core portion 11A and the second winding core portion 12A is connected to approximately the center in the Z-axis direction of the inner end surface 13d of the first flange portion 13. The other end of each of the first winding core portion 11A and the second winding core portion 12A is connected to approximately the center in the Z-axis direction of the inner end surface 14d of the second flange portion 14.

[0078] Therefore, the upper part of first winding core 11A does not protrude above upper surface 13a of first flange 13 or upper surface 14a of second flange 14, but is located below upper surfaces 13a and 14a. In addition, the upper part of second winding core 12A does not protrude above upper surface 13a of first flange 13 or upper surface 14a of second flange 14, but is located below upper surfaces 13a and 14a.

[0079] 7, the terminal electrodes 41A to 44A have a substantially L-shape. That is, the terminal electrodes 41A to 44A can be regarded as terminals obtained by omitting the connecting portions 411 to 441, the sandwiching portions 413a to 443a, and the sandwiching portions 413b to 443b from the terminal electrodes 41 to 44 of the first embodiment shown in FIG.

[0080] As shown in FIG. 9, the lead portion 31a of the first coil 31 is connected to the bottom surface (surface connected to the mounting board) of the mounting portion 410 of the terminal electrode 41A. Furthermore, the lead portion 32a of the second coil 32 is connected to the bottom surface (surface connected to the mounting board) of the mounting portion 410 of the terminal electrode 42A. Furthermore, as shown in FIG. 10, the lead portion 32b of the second coil 32 is connected to the bottom surface of the mounting portion 440 of the terminal electrode 44A. Although not shown in detail, the lead portion 31b of the first coil 31 is also connected to the bottom surface of the mounting portion 430. That is, in this embodiment, the lead portions 31a and 32a are connected to the bottom surface 13b of the first flange 13, not the top surface 13a. Furthermore, the lead portions 31b and 32b are connected to the bottom surface 14b of the second flange 14, not the top surface 14a.

[0081] Therefore, as shown in Fig. 7, the auxiliary core 20A can be stably installed on the upper surface 13a of the first flange 13 and the upper surface 14a of the second flange 14. The auxiliary core 20A in this embodiment has only a main body 21 having a rectangular parallelepiped shape, and does not have any of the first outer leg 22a, the second outer leg 22b, or the center leg 23 (Fig. 6). In other words, the auxiliary core 20A is a flat (I-shaped) core. Therefore, the main body 21 directly abuts on the upper surface 13a of the first flange 13 and the upper surface 14a of the second flange 14.

[0082] When auxiliary core 20A is fixed to main core 10A, the entire upper surface 13a of first flange 13 abuts against the bottom surface (lower surface) of main body 21 at one end of main body 21 in the X-axis direction. Furthermore, the entire upper surface 14a of second flange 14 abuts against the bottom surface of main body 21 at the other end of main body 21 in the X-axis direction. Therefore, the contact area between the bottom surface of main body 21 and upper surface 13a is approximately equal to the area of ​​upper surface 13a, and the contact area between the bottom surface of main body 21 and upper surface 14a is approximately equal to the area of ​​upper surface 14a.

[0083] This embodiment also achieves the same effects as the first embodiment. In particular, in this embodiment, the auxiliary core 20A is fixed in close contact with the main core 10A without any gaps between the main body 21 and the upper surface 13a of the first flange 13 or between the main body 21 and the upper surface 14a of the second flange 14. This allows the auxiliary core 20A to be in contact with the main core 10A over a relatively large contact area. This allows the main core 10A to efficiently transmit stress to the auxiliary core 20A when stress is generated in the main core 10A due to twisting of the mounting board, for example, and effectively enhances the auxiliary core 20A's ability to dissipate (absorb) stress.

[0084] Furthermore, in this embodiment, the auxiliary core 20A does not include the first outer leg portion 22a or the like, so the thickness of the main body portion 21 can be made relatively thick. Although the thickness of the main body portion 21 shown in Fig. 7 is smaller than the thickness of the first flange portion 13, as shown in Fig. 13, the thickness of the main body portion 21 may be larger than the thickness of the first flange portion 13. In this case, the volume of the auxiliary core 20A can be increased significantly, and the ability of the auxiliary core 20A to disperse (absorb) stress can be further effectively improved.

[0085] Furthermore, in this embodiment, because the lead portions 31a of the first coil 31 and the lead portions 32a of the second coil 32 are arranged on the mounting surface of the first flange 13, the auxiliary core 20A can be fixed to the surface opposite the mounting surface of the first flange 13 without being obstructed by these portions. Furthermore, because the lead portions 31b of the first coil 31 and the lead portions 32b of the second coil 32 are arranged on the mounting surface of the second flange 14, the auxiliary core 20A can be fixed to the surface opposite the mounting surface of the second flange 14 without being obstructed by these portions.

[0086] 11A and 11B are diagrams obtained by simulation of the distribution of stress applied to the main core 10A in the coil device 1A shown in Fig. 7. Fig. 11A is a diagram of the main core 10A viewed from the mounting surface side, and Fig. 11B is a diagram of the main core 10A viewed from the opposite side to the mounting surface. Note that in this simulation, the first coil 31 and the second coil 32 are not provided on the first winding core part 11A and the second winding core part 12A.

[0087] 12A and 12B are diagrams obtained by simulation of the distribution of stress applied to the main core 10 shown in FIG. 2. FIG. 12A is a view of the main core 10 from the mounting surface side, and FIG. 12B is a view of the main core 10 from the opposite side to the mounting surface. Terminal electrodes 41 to 44 shown in FIG. 5 are attached to the main core 10, and the auxiliary core 20 is not fixed. Furthermore, the first coil 31 and the second coil 32 are not provided on the first winding core portion 11 and the second winding core portion 12.

[0088] In this simulation, the mounting surface of main core 10 or main core 10A is fixed to a mounting substrate having a flattened rectangular parallelepiped shape as shown in FIG. 13. In this state, an external force (torsion) is applied to the mounting substrate so that each of its four corners is displaced in the direction indicated by the arrows in the figure. In FIGS. 11A and 11B, the distribution of stress applied to main core 10A at this time is indicated by the density of dots. In FIGS. 11A and 11B, areas with high density dots are subjected to relatively large stresses, and areas with low density dots are subjected to relatively small stresses. The same is true for FIGS. 12A and 12B.

[0089] As shown in Figures 11A and 11B, when the auxiliary core 20A is fixed to the main core 10A, it can be seen that the stress applied to the core 10A is relatively small, particularly near the boundaries between each winding core portion (first winding core portion 11A and second winding core portion 12A) and each flange portion (first flange portion 13 and second flange portion 14).

[0090] 12A and 12B, when the auxiliary core 20 is not fixed to the main core 10, the stress acting on the core 10 is relatively large, particularly near the boundaries between the winding core portions (first winding core portion 11 and second winding core portion 12) and the flange portions (first flange portion 13 and second flange portion 14). Simulations revealed that stresses of 120 N / mm or more are acting on these portions, exceeding the 100 N / mm threshold at which the main core 10 is damaged.

[0091] As described above, the simulation results also confirmed that fixing auxiliary core 20A to main core 10A provides a high stress dispersion effect and protects main core 10A from stress.

[0092] Third embodiment The coil device 1B according to the third embodiment of the present invention shown in Fig. 14 has the same configuration as the coil device 1 according to the first embodiment, except for the following points: In Fig. 14, the same members as those of the coil device 1 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0093] As shown in Fig. 14, the coil device 1B has an auxiliary core 20B. As is clear from comparing Fig. 15 with Fig. 6, in the auxiliary core 20B of this embodiment, the center leg 23 is not formed on the main body 21, and only the first outer leg 22a and the second outer leg 22b are formed on the main body 21. In other words, the auxiliary core 20B is a substantially U-shaped core.

[0094] 14, below the main body 21 (between the main body 21 and the main core 10), a gap G3 is formed, which is defined by the lower surface of the main body 21 and the first and second outer legs 22a and 22b. Unlike the gaps G1 and G2 shown in FIG. 1, the gap G3 extends in the Y-axis direction from the position of the first outer leg 22a to the position of the second outer leg 22b.

[0095] The same effects as those of the first embodiment can be obtained in this embodiment. In particular, in this embodiment, when the auxiliary core 20B is fixed to the side opposite the mounting surface of the main core 10, the center leg portion 23 is not disposed between the terminal electrodes 41 and 42 (between the terminal electrodes 43 and 44) ​​or between the first winding core portion 11 and the second winding core portion 12. This makes it possible to ensure a sufficient spatial volume for the gap G3, and increases the degree of freedom in designing the coil device 1B, such as by increasing the number of layers of the first coil 31 and the second coil 32.

[0096] Fourth embodiment A coil device 1C according to a fourth embodiment of the present invention shown in Fig. 16 has the same configuration as the coil device 1A according to the second embodiment, except for the following points: In Fig. 16, members that overlap with those of the coil device 1A according to the second embodiment are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0097] 16, the coil device 1C has the main core 10A of the second embodiment and the auxiliary core 20B of the third embodiment. In this embodiment, when the auxiliary core 20B is fixed to the main core 10A, the orientation of the auxiliary core 20B is different from that of the coil device 1B of the third embodiment. That is, in this embodiment, the auxiliary core 20B is fixed to the main core 10A so that the opposing direction (X-axis direction) of the first outer leg portion 22a and the second outer leg portion 22b substantially coincides with the opposing direction (X-axis direction) of the first flange portion 13 (inner end surface 13d) and the second flange portion 14 (inner end surface 14d).

[0098] Therefore, the entire bottom surface of the first outer leg 22a abuts against the upper surface 13a of the first flange 13. Also, the entire bottom surface of the second outer leg 22b abuts against the upper surface 14a of the second flange 14. In this manner, in this embodiment, most of the first outer leg 22a can be brought into contact with the upper surface 13a of the first flange 13, thereby ensuring a sufficient contact area therebetween and enhancing the unity between the first outer leg 22a and the first flange 13. Also, most of the second outer leg 22b can be brought into contact with the upper surface 14a of the second flange 14, thereby ensuring a sufficient contact area therebetween and enhancing the unity between the second outer leg 22b and the second flange 14. As a result, the ability of the auxiliary core 20B to disperse (absorb) stress can be effectively improved.

[0099] From the viewpoint of enhancing the effect of dispersing stress from main core 10A to auxiliary core 20B, it is preferable that the widths in the X-axis direction of first outer leg 22a and second outer leg 22b are approximately equal to the widths in the X-axis direction of first flange 13 and second flange 14, respectively. This ensures a sufficiently large stress dispersion path, enhancing the above-mentioned stress dispersion effect.

[0100] Fifth embodiment A coil device 1D according to a fifth embodiment of the present invention shown in Fig. 17 has the same configuration as the coil device 1 according to the first embodiment, except for the following points. In Fig. 17, members other than the auxiliary core 20D are not shown. In Fig. 17, members that overlap with those of the coil device 1 according to the first embodiment are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0101] 17, the auxiliary core 20D has, in addition to the main body 21, first legs 24a to 24d that protrude downward from the bottom surface of the main body 21. The first legs 24a to 24d are formed at the four corners of the main body 21. The first leg 24a is formed at the first corner 21a of the main body 21, the second leg 24b is formed at the second corner 21b of the main body 21, the third leg 24c is formed at the third corner 21c of the main body 21, and the fourth leg 24d is formed at the fourth corner 21d of the main body 21.

[0102] The first legs 24a to 24d have a columnar shape (rectangular parallelepiped shape). However, the shape of the first legs 24a to 24d is not limited to the shape shown in the figure, and may be a cylindrical shape, a triangular prism shape, or any other polygonal prism shape.

[0103] Although four first legs 24a to 24d are formed on main body 21, the number of legs is not limited to this. For example, another leg (fifth leg) may be formed at an intermediate position between first leg 24a and second leg 24b. Also, another leg (sixth leg) may be formed at an intermediate position between third leg 24c and fourth leg 24d.

[0104] The first leg 24a and the second leg 24b are fixed to the upper surface 13a of the first flange 13 shown in Fig. 2 at a predetermined interval in the Y-axis direction. The third leg 24c and the fourth leg 24d are fixed to the upper surface 14a of the second flange 14 shown in Fig. 2 at a predetermined interval in the Y-axis direction. When the fifth and sixth legs described above are formed on the main body 21, the fifth leg is fixed to the upper surface 13a of the first flange 13 between the terminal electrodes 41 and 42 shown in Fig. 4, and the sixth leg is fixed to the upper surface 14a of the second flange 14 between the terminal electrodes 43 and 44 shown in Fig. 4.

[0105] The widths of the first leg portion 24a to the fourth leg portion 24d in the X-axis direction are smaller than the widths of the first flange portion 13 and the second flange portion 14 shown in FIG. 2, but from the viewpoint of enhancing the effect of dispersing stress from the main core 10 to the auxiliary core 20D, it is preferable that they are approximately equal.

[0106] This embodiment can also achieve the same effects as the first embodiment. In particular, in this embodiment, the first to fourth leg portions 24a to 24d are formed locally (spot-like) at the four corners of the main body portion 21. Therefore, when the auxiliary core 20D is fixed to the main core 10 shown in Fig. 4, a gap extending in the X-axis direction is formed between the first leg portion 24a and the third leg portion 24c, and a gap extending in the X-axis direction is formed between the second leg portion 24b and the fourth leg portion 24d. This prevents the first coil 31 and the second coil 32 from interfering with the first to fourth leg portions 24c to 24d.

[0107] The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention.

[0108] In the above embodiments, the present invention has been described as being applied to a common mode filter. However, the present invention can also be applied to a difference mode filter. When the coil device 1 is used as a difference mode filter, the auxiliary core 20 may be made of a magnetic material. Alternatively, even when the coil device 1 is used as a common mode filter, the auxiliary core 20 may be made of a magnetic material to adjust its magnetic characteristics. In this case, the auxiliary core 20 may be made of the same material as the main core 10. For example, the auxiliary core 20 may be made of a composite magnetic material containing ferrite, a metal magnetic material, and a resin, or a sintered metal magnetic material.

[0109] In the above embodiments, examples of application of the present invention to filters have been described, but the present invention can also be applied to other coil devices such as transformers, in addition to filters.

[0110] In the first embodiment, the clamping portions (clamping portion 413a, etc.) of the terminal electrodes 41 to 44 shown in Fig. 5 may be omitted. In this case, for example, the lead portion 31a of the first coil 31 may be connected to the connecting portion 411 by the connecting member 50 (Fig. 1) without being clamped by the clamping portions 413a and 413b.

[0111] In the first embodiment, the auxiliary core 20 shown in FIG. 1 may be fixed to the main core 10A of the second embodiment shown in FIG. 8. In the third embodiment, the auxiliary core 20B shown in FIG. 14 may be fixed to the main core 10A of the second embodiment shown in FIG. 8. In the fifth embodiment, the auxiliary core 20D shown in FIG. 17 may be fixed to the main core 10A of the second embodiment shown in FIG. 8. In the second embodiment, the auxiliary core 20A shown in FIG. 7 may be fixed to the main core 10 shown in FIG. 2. In this case, however, the design must be modified so that the upper portions of the first winding core portion 11 and the second winding core portion 12 do not protrude above the upper surface 13a of the first flange portion 13 and the upper surface 14a of the second flange portion 14. In the fourth embodiment, the auxiliary core 20B shown in FIG. 16 may be fixed to the main core 10 shown in FIG. 2 in the orientation shown in the figure. [Example]

[0112] The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.

[0113] Example Five coil device samples were fabricated by fixing auxiliary core 20B, shown in FIG. 15, to the surface opposite the mounting surface of main core 10, shown in FIG. 2, in the manner shown in FIG. 16. In fabricating the samples, a ferrite core was used as main core 10. Furthermore, first outer leg 22a and second outer leg 22b of auxiliary core 20B were bonded with epoxy resin to upper surface 13a of first flange 13 and upper surface 14a of second flange 14 of main core 10, respectively. Furthermore, the installation of first coil 31, second coil 32, and terminal electrodes 41 to 44 was omitted.

[0114] The fabricated samples were fixed to the mounting board shown in Figure 13, and an external force was applied to the mounting board so that each corner (four corners) of the mounting board was displaced by an equal amount in the direction indicated by the arrows in the figure, thereby generating a twist in the mounting board. When twisting the mounting board, one end of the mounting board in the X-axis direction was fixed with a jig, and an external force was applied to the other end of the mounting board in the X-axis direction via the jig. At this time, for each sample, the amount of displacement of each corner of the mounting board when cracks occurred in the main core 10 (i.e., the degree of twist) was measured with a digital multimeter. The results are shown in Table 1. In Table 1, "-" indicates that no cracks occurred in the main core 10.

[0115] Comparative Example Five samples each consisting of the main core 10 shown in Fig. 2 were fabricated and subjected to the same measurements as in the example. The results are shown in Table 1.

[0116] [Table 1]

[0117] As shown in Table 1, in the examples, no cracks occurred in main core 10 for any of the samples, even though a predetermined amount of twist was applied to the mounting substrate. Furthermore, in any of the samples, no cracks occurred in main core 10, even when the mounting substrate was displaced by 8 mm or more.

[0118] On the other hand, in the comparative example, cracks occurred in the main core 10 when the displacement of the mounting board was 1.568 mm on average. From the above, it was confirmed that by fixing the auxiliary core 20B to the main core 10, the auxiliary core 20B has the effect of alleviating stress on the main core 10, and damage to the main core 10 can be effectively prevented. [Explanation of symbols]

[0119] 1, 1A, 1B, 1C, 1D... Coil device 10,10A...Main core 11,11A…Volume 1 core part 110...upper tapered section 12,12A…Volume 2 core part 120...upper tapered section 13...First flange 131, 132...Outer recess 133, 134...Step section 133a, 134a...Tapered portion 135...Inner recess 14...Second flange 141, 142...Outer recess 143, 144...Step section 143a, 144a...Tapered portion 145...Inner recess 15...Central hole 20, 20A, 20B, 20D...Auxiliary core 21...Main body 22a, 22b...outer leg part 23...middle leg 24a~24d…legs 31...First coil 31a, 31b...Lead section 32...Second coil 32a, 32b...Lead section 41~44,41A~44A…Terminal electrode 410, 420, 430, 440... Mounting section 411,421,431,441…Connection section 412,422,432,442...Connection part 413a, 413b, 423a, 423b, 433a, 433b, 443a, 443b...Pinch part 50...Connecting member

Claims

1. a first winding core around which the first coil is wound; a second winding core portion disposed substantially parallel to the first winding core portion and around which a second coil is wound; a first flange portion at which one axial end of the first winding core portion and one axial end of the second winding core portion are connected; a main core including a second flange portion to which the other axial end of the first winding core portion and the other axial end of the second winding core portion are connected; an auxiliary core made of a non-magnetic material and fixed to the main core on the side opposite to the mounting surface so as to straddle the first flange and the second flange; the auxiliary core has a main body portion having a rectangular parallelepiped shape, and a first outer leg portion and a second outer leg portion formed on the main body portion at a predetermined interval and extending substantially parallel to each other; the first outer leg portion is fixed to the first flange portion and the second flange portion so as to bridge the first flange portion and the second flange portion along the first winding core portion, The second outer leg portion is fixed to the first flange portion and the second flange portion so as to bridge the first flange portion and the second flange portion along the second winding core portion.

2. the auxiliary core has a middle leg portion formed in the main body portion, the middle leg portion being between the first outer leg portion and the second outer leg portion and extending substantially parallel to the first outer leg portion and the second outer leg portion; The coil device according to claim 1, wherein the center leg portion is fixed to the first flange portion and the second flange portion so as to bridge the first flange portion and the second flange portion between the first winding core portion and the second winding core portion.

3. the coil further comprises a first terminal electrode provided on the first flange and connected to one lead portion of the first coil, a second terminal electrode provided on the first flange and connected to one lead portion of the second coil, a third terminal electrode provided on the second flange and connected to the other lead portion of the first coil, and a fourth terminal electrode provided on the second flange and connected to the other lead portion of the second coil, the first terminal electrode and the third terminal electrode are located between the first outer leg portion and the middle leg portion, The coil device according to claim 2 , wherein the second terminal electrode and the fourth terminal electrode are located between the second outer leg portion and the middle leg portion.

4. a first winding core around which the first coil is wound; a second winding core portion disposed substantially parallel to the first winding core portion and around which a second coil is wound; a first flange portion at which one axial end of the first winding core portion and one axial end of the second winding core portion are connected; a main core including a second flange portion to which the other axial end of the first winding core portion and the other axial end of the second winding core portion are connected; an auxiliary core made of a non-magnetic material and fixed to the main core on the side opposite to the mounting surface so as to straddle the first flange and the second flange; The auxiliary core has a main body portion having a rectangular parallelepiped shape, one end of the main body abuts against a surface of the first flange portion opposite to the mounting surface, The other end of the main body abuts against a surface of the second flange opposite to the mounting surface of the coil device.

5. a first winding core around which the first coil is wound; a second winding core portion disposed substantially parallel to the first winding core portion and around which a second coil is wound; a first flange portion at which one axial end of the first winding core portion and one axial end of the second winding core portion are connected; a main core including a second flange portion to which the other axial end of the first winding core portion and the other axial end of the second winding core portion are connected; an auxiliary core made of a non-magnetic material and fixed to the main core on the side opposite to the mounting surface so as to straddle the first flange and the second flange; the auxiliary core has a main body portion having a rectangular parallelepiped shape, and a first outer leg portion and a second outer leg portion formed on the main body portion at a predetermined interval and extending substantially parallel to each other; the first outer leg abuts against a surface of the first flange opposite to a mounting surface, the second outer leg portion abuts against a surface of the second flange portion opposite to the mounting surface, a direction in which the first outer leg portion and the second outer leg portion face each other substantially coincides with a direction in which the first flange portion and the second flange portion face each other, the first outer leg portion is perpendicular to the axial direction of the first winding core portion and covers from one end to the other end of a surface of the first flange portion opposite the mounting surface, along a direction parallel to the mounting surface of the first flange portion; The second outer leg portion is perpendicular to the axial direction of the second winding core portion and covers the surface opposite the mounting surface of the second flange portion from one end to the other end along a direction parallel to the mounting surface of the second flange portion.

6. the coil further comprises a first terminal electrode provided on the first flange and connected to one lead portion of the first coil, a second terminal electrode provided on the first flange and connected to one lead portion of the second coil, a third terminal electrode provided on the second flange and connected to the other lead portion of the first coil, and a fourth terminal electrode provided on the second flange and connected to the other lead portion of the second coil, one lead portion of the first coil is connected to the first terminal electrode on a mounting surface of the first flange portion, one lead portion of the second coil is connected to the second terminal electrode on a mounting surface of the first flange portion, the other lead portion of the first coil is connected to the third terminal electrode on the mounting surface of the second flange portion, The coil device according to claim 4 or 5, wherein the other lead portion of the second coil is connected to the fourth terminal electrode on a mounting surface of the second flange portion.

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