Coil device

Abstract

To obtain a coil device which can be reduced in height and can prevent winding collapse of a winding.SOLUTION: The bobbin 10 included in the coil device has the cylindrical portion 12 around which the winding is wound, and the upper flange portion 14 and the lower flange portion 16 respectively formed on both sides of the cylindrical portion 12 in the axial direction, the winding 3 is spirally wound around the cylindrical portion 12 between the upper flange portion 14 and the lower flange portion 16, and the bobbin 10 includes the winding guide portion 12A that guides the second winding along the circumferential direction of the first winding wound around the cylindrical portion 12.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a coil device. [Background technology]

[0002] Patent Document 1 discloses a resin bobbin having a cylindrical winding drum around which a winding is wound and flange-like portions on both ends of the winding drum. This resin bobbin, together with an upper core assembled to the upper flange side and a lower core assembled to the lower flange side, constitutes a coil device, and the coil device is designed so that no core is disposed inside the winding drum, leaving only a magnetic gap inside the winding drum, thereby reducing the height of the coil device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-212275 Summary of the Invention [Problem to be solved by the invention]

[0004] The height of a coil device varies greatly depending on the method of winding the wire. For example, one method involves winding the wire in a spiral shape around the cylindrical portion of a bobbin. This method allows for the formation of a single-layer winding in the height direction (axial direction) of the coil device, which allows for a lower bobbin height compared to methods in which the wire is wound in a multi-layer structure.

[0005] However, when winding the wire in a spiral shape, the second winding is wound so that it crosses the beginning of the first winding, which poses a problem that the beginning of the second winding is not stably supported, making it more likely for the winding to become unbalanced.

[0006] The present invention has been made to solve the above-mentioned problems, and has an object to provide a coil device that can be made low-profile and can prevent the winding from becoming unwound. [Means for solving the problem]

[0007] The bobbin of the present invention has a cylindrical portion around which a winding is wound and two flange portions formed on both axial sides of the cylindrical portion, and the winding is wound spirally around the cylindrical portion between the two flange portions, and is provided with a winding guide portion that guides the second winding along the circumferential direction of the first winding wound around the cylindrical portion. [Effects of the Invention]

[0008] The bobbin according to the present invention includes a cylindrical portion around which the wire is wound, and the wire is spirally wound between two flanges formed on both axial sides of the cylindrical portion. This results in a single-layer structure, allowing the bobbin to have a low profile. The bobbin is also provided with a winding guide portion that guides the second winding along the circumferential direction of the first winding wound around the cylindrical portion. This allows the second winding, which is positioned to cross the beginning of the first winding, to be stably supported by the winding guide portion, thereby preventing the winding from becoming unbalanced. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of a coil device according to an embodiment. [Figure 2] 2 is a cross-sectional view of the coil device taken along line II-II in FIG. 1. FIG. [Figure 3] FIG. 2 is an exploded perspective view of the coil device according to the embodiment. [Figure 4] FIG. 2 is a planar perspective view of the bobbin according to the embodiment. [Figure 5] FIG. 2 is a bottom perspective view of the bobbin according to the embodiment. [Figure 6] FIG. 2 is a side view of the bobbin according to the embodiment, seen from the rear side. [Figure 7] 7 is a cross-sectional view of the bobbin taken along line VII-VII in FIG. 6. FIG. [Figure 8]FIG. 10 is a perspective plan view showing a first modified example of the bobbin according to the embodiment. [Figure 9] FIG. 10 is a perspective plan view showing a second modified example of the bobbin according to the embodiment. [Figure 10] FIG. 10 is a side view showing a third modified example of the bobbin according to the embodiment, in which the bobbin is seen from the right side. [Figure 11] 10A and 10B are side views showing a third modified example of the bobbin according to the embodiment, where (A) shows a side view of the bobbin as seen from the front side, and (B) shows a side view of the bobbin as seen from the rear side. [Figure 12] 8A and 8B are partial cross-sectional views corresponding to FIG. 7 showing modified examples of the winding guide part according to the embodiment, where (A) shows a first modified example of the winding guide part, and (B) shows a second modified example of the winding guide part. DETAILED DESCRIPTION OF THE INVENTION

[0010] A coil device 1 according to an embodiment of the present invention and a bobbin 10 used in the coil device 1 will be described below with reference to Figures 1 to 7. In this embodiment, for convenience of explanation, the directions indicated by the up / down, left / right, and front / rear arrows shown appropriately in each figure will be defined as the up / down direction, left / right direction, and front / rear direction, respectively. Also, in each figure, some reference numerals may be omitted to make the drawings easier to understand.

[0011] 1 to 3, the coil device 1 of this embodiment constitutes a choke coil, for example. The coil device 1 includes a core 2 made of a magnetic material such as a ferrite core, a bobbin 10 through which the core 2 is inserted, and a winding 3 wound around the bobbin 10.

[0012] The core 2 has a first core 2A attached to the rear of the bobbin 10 and a second core 2B attached to the front of the bobbin 10. The first and second cores 2A and 2B each have an upper core 21 arranged above the bobbin 10 and a lower core 22 arranged below the bobbin 10. The upper core 21 and the lower core 22 are molded separately and are joined in an overlapping state so as to sandwich the bobbin 10 from above and below.

[0013] As shown in FIGS. 2 and 3 , the upper core 21 has a core side portion 211, a center leg portion 212, and an outer leg portion 213, and has a generally E-shaped cross section in the vertical and horizontal directions. The core side portion 211 has a predetermined thickness in the vertical direction and is formed like a plate that is generally rectangular in plan view. The center leg portion 212 is formed like a cylinder with its axial direction in the vertical direction and stands downward (toward the lower core 22) from the lower surface of the core side portion 211. The outer leg portions 213 are formed like vertical walls with a predetermined thickness in the vertical direction and stand downward from both the left and right sides of the core side portion 211. When the upper core 21 is attached to the bobbin 10, the bobbin 10 is housed inside the outer leg portions 213, and the center leg portions 212 are inserted into the inside of a cylindrical portion 4 of the bobbin 10, which will be described later.

[0014] The lower core 22 has a predetermined thickness in the vertical direction and is formed like a plate that is approximately rectangular in plan view, with its top, bottom, left, and right cross sections being approximately I-shaped. The lower core 22 is disposed below the upper core 21, so that its upper surface abuts against the lower surfaces of the center leg portion 212 and the outer leg portion 213 of the upper core 21. After the upper core 21 and the lower core 22 are stacked one on top of the other, they are joined to each other by wrapping insulating tape (not shown). As a result, in the first core 2A and the second core 2B, a closed magnetic circuit is formed that runs from the center leg portion 212 of the upper core 21 through the core side portion 211 and the outer leg portion 213 and around the lower core 22.

[0015] 4 and 5, the bobbin 10 has a cylindrical portion 12 around which the winding 3 is wound, and two flanges 14, 16 formed on both axial sides of the cylindrical portion 12. The bobbin 10 is made of, for example, an insulating resin material, and is configured as a one-piece molded product by injection molding.

[0016] As shown in FIG. 7 , the cylindrical portion 12 is formed into an elliptical cylindrical shape with its axis extending vertically. The winding 3 is spirally wound around the outer circumferential surface of the cylindrical portion 12. As an example, the winding 3 is made of a Litz wire formed by twisting together multiple wires (thin wires). The winding 3 has a start point 3B of the first turn located at the rear end of the cylindrical portion 12. The winding 3 is wound clockwise around the outer circumferential surface of the cylindrical portion 12 without moving the start point 3B of the first turn. The second turn 3D of the winding 3 intersects with the start point 3B of the first turn, and the second turn 3D of the winding 3 is wound around the outer circumferential side (radially outward) of the first turn 3D. In this way, the spiral winding 3 is formed by winding the winding 3 multiple times in the radial direction.

[0017] A winding guide portion 12A that protrudes radially outward is integrally provided at one end (the rear end in FIG. 7 ) of the tubular portion 12. This winding guide portion 12A is disposed along the circumferential direction of the first winding 3 and can guide the second winding 3 along the circumferential direction of the first winding 3 wound around the tubular portion 12. That is, the winding end 3C of the first winding 3 wound around the tubular portion 12 is guided along the winding guide portion 12A toward the outer periphery of the first winding, thereby guiding the winding start 3D of the second winding 3 toward the outer periphery along the circumferential direction of the first winding 3. As a result, the winding start 3D of the second winding 3 is stably supported by the winding guide portion 12A.

[0018] Furthermore, in this embodiment, the winding guide portion 12A is provided adjacent to the winding start 3B of the first winding 3. This positions the winding start 3D of the second winding 3 next to the winding start 3B of the first winding radially outward, effectively preventing the winding start 3D of the second winding from riding over and overlapping the winding start 3B of the first winding. That is, the shape of the winding start 3B of the first winding 3 is unstable during the manufacturing process due to the routing of the end 3A pulled out from the winding start 3B. Therefore, by preventing the second winding 3 from riding over the winding start 3B, the shape of the second winding 3 can be stabilized from the winding start 3D.

[0019] The tubular portion 12 further has a partition wall portion 18 that divides the space inside the tubular portion 12 into front and rear portions. The partition wall portion 18 forms two cylindrical portions 121, 122 that vertically penetrate the bobbin 10 inside the tubular portion 12. As shown in Fig. 3, the center leg portions 212 of the first and second cores 2A, 2B are inserted into the two cylindrical portions 121, 122, respectively.

[0020] As shown in Figures 4 and 5, the two flanges 14, 16 formed on both axial sides of the tubular portion 12 are composed of an upper flange 14 and a lower flange 16. The upper flange 14 protrudes radially outward from the outer peripheral surface of the upper end of the tubular portion 12 and is a plate-like member formed in a substantially rectangular shape in a plan view. A pair of upper wall portions 26 are provided on the upper surface of the upper flange 14, each extending from the front and rear ends of the upper flange 14 to one side in the axial direction of the tubular portion 12 (the upper side in Figure 4). A partition wall portion 28 is formed between the pair of upper wall portions 26, dividing the upper surface of the upper flange 14 into front and rear sections. The partition wall portion 28 is disposed between two cylindrical portions 121, 122 formed inside the tubular portion 12 and stands upward from the upper surface of the upper flange 14. When the core 2 is assembled to the bobbin 10, the upper cores 21 of the first and second cores 2A, 2B are respectively arranged on both sides of the partition wall portion 28, and the upper cores 21 of the first and second cores 2A, 2B are supported from both sides in the front-to-rear direction by a pair of upper wall portions 26 and the partition wall portion 28 (see Figure 1).

[0021] The lower flange 16 protrudes radially outward from the outer peripheral surface of the lower end of the tubular portion 12 and is a plate-like member formed into a substantially rectangular shape in a plan view. Similar to the above-described upper flange 14, a pair of lower wall portions 30 are provided on the lower surface of the lower flange 16, each extending from the front and rear ends of the lower flange 16 to one side in the axial direction of the tubular portion 12 (the downward side in FIG. 5 ). A partition wall portion 32 is formed between the pair of lower wall portions 30, dividing the lower surface of the lower flange 16 into front and rear portions. The partition wall portion 32 is disposed between two cylindrical portions 121, 122 formed inside the tubular portion 12 and stands downward from the lower surface of the lower flange 16. When the core 2 is assembled to the bobbin 10, the lower cores 22 of the first and second cores 2A, 2B are respectively arranged on both sides of the partition wall portion 32, and the lower cores 22 of the first and second cores 2A, 2B are supported from both sides in the front-to-rear direction by a pair of lower wall portions 30 and partition wall portion 32.

[0022] As shown in FIG. 6 , the lower wall 30 extending from the rear end of the lower flange 16 is provided with a winding lead-out portion 40, through which an end 3A of the first turn of the winding 3 wound around the tubular portion 12 is led out. The winding lead-out portion 40 is formed by grooves formed in the lower wall 30, and includes a first groove 42 and a second groove 44. The first groove 42 extends obliquely downward from the upper surface of the lower flange 16 (toward one axial side of the tubular portion 12). The second groove 44 is provided continuous with the first groove 42 and extends from the first groove 42 radially outward of the tubular portion 12 (to the right in FIG. 6 ) until it reaches the end of the lower wall 30 (opening rightward from the right end of the lower wall 30). The end 3A of the first turn of the winding 3 led out from the winding start 3B is inserted into the first and second grooves 44, 46. The end 3A of the winding 3 is guided by the first groove 42 and pulled out to the axial outside of the tubular portion 12 (below the lower flange 16). Then, while held in the second groove 44, the position of the lead wire extending from the end 3A of the first turn of the winding 3 can be determined. In other words, the section between the upper flange 14 and the lower flange 16 essentially contains only the winding 3 with a single layer structure formed in a spiral shape. This keeps the axial dimension of the tubular portion 12 to a height equivalent to approximately one diameter of the winding.

[0023] With the bobbin 10 configured as described above, the spiral winding 3 can be formed by winding wire around the tubular portion 12 manually or automatically using an automatic winding machine. In Figure 6, the process of winding the winding 3 around the tubular portion 12 of the bobbin 10 is shown by two-dot chain lines. As shown in this figure, in the manufacturing process, the end 3A of the winding 3 is inserted into the first groove 42 and the second groove 44 of the winding pull-out portion 40. Then, the portion that passes through the first groove 42 and is pulled out between the upper flange 14 and the lower flange 16 becomes the winding start 3B of the first turn, and the position of the winding start 3B of the winding 3 can be set.

[0024] Here, end 3A of winding 3 passes through first groove 42 and second groove 44 of winding lead-out portion 40 and is pulled out from the end of lower wall 30 (the right end in FIG. 6 ), so winding of winding 3 can be performed with a predetermined tension T applied along the direction of extension of second groove 44. End 3E of winding 3, where the winding ends, is pulled out from between upper flange 14 and lower flange 16 to the rear side of bobbin 10, similar to end 3A of winding 3 of the first turn.

[0025] (Action and effect) As described above, the bobbin 10 according to this embodiment includes the cylindrical portion 12 around which the winding 3 is wound, and the winding 3 is spirally wound between the upper flange 14 and the lower flange 16 formed on both axial sides of the cylindrical portion 12. Therefore, the winding 3 has a single-layer structure, which allows the bobbin to have a low profile. Here, as shown in FIG. 7 , the bobbin 10 is provided with a winding guide portion 12A that guides the second winding 3 along the circumferential direction of the first winding 3 wound around the cylindrical portion 12. As a result, the second winding 3, which is disposed so as to intersect with the winding start 3B of the first winding 3, is stably supported by the winding guide portion 12A, thereby preventing the winding 3 from becoming unbalanced.

[0026] Furthermore, the winding guide portion 12A is located adjacent to the winding start 3B of the first winding 3. Therefore, the winding start 3D of the second winding is positioned radially outside the winding start 3B of the first winding and does not ride up onto the winding start 3B of the first winding. As a result, the shape of the second winding 3 can be stabilized from the winding start 3D, and the winding of the winding 3 can be more effectively prevented from becoming unwound.

[0027] The bobbin 10 according to this embodiment is also provided with a winding lead-out portion 40 that leads the end 3A drawn out from the first winding 3 to one axial side of the tubular portion 12 relative to the second winding 3. Specifically, the winding lead-out portion 40 is composed of a first groove 42 and a second groove 44 formed in the lower wall portion 30 that extends from the end (rear end) of the lower flange 16 to one axial side of the tubular portion.

[0028] Therefore, end 3A of the first winding 3 is pulled out to one axial side of tubular portion 12 via winding pull-out portion 40, so that only the spiral winding portion is housed between upper flange 14 and lower flange 16 formed on either side of tubular portion 12. This makes it possible to realize a bobbin structure in which the axial dimension of tubular portion 12 is limited to the height of one winding diameter, thereby facilitating the reduction in height of bobbin 10. Furthermore, winding pull-out portion 40 makes it possible to keep the position of end 3A pulled out from the first winding 3 constant, making it easier to connect the winding 3 to terminals, etc.

[0029] Furthermore, because the first and second grooves 44, 46 that make up the winding draw-out portion 40 are formed in the lower wall portion 30 that extends from the end of the lower flange 16, the end 3A of the first turn of the winding 3 is positioned along the outer surface of the bobbin 10. This makes it easy to set the wire that will become the winding 3 at the winding start position, improving the efficiency of the work involved in winding the winding 3.

[0030] Furthermore, the first groove 42 is inclined toward one side in the axial direction of the tubular portion 12, and the second groove 44 extends from the first groove 42 radially outward of the tubular portion 12, reaching the end (right end) of the lower wall portion 30. Therefore, as shown by the two-dot chain line in Figure 6, in the manufacturing process, winding can be performed with a predetermined tension T applied to the wire constituting the winding 3 along the extension direction of the second groove 44. This improves the efficiency of the winding of the winding 3 and also enables automation using an automatic winding machine.

[0031] Furthermore, because the lower wall portion 30 is provided at the end of the lower flange 16, the outer periphery of the spiral winding 3 is partially exposed beyond the end of the lower flange 16. With this structure, heat from the portion of the winding exposed beyond the end of the lower flange 16 can be dissipated to the outside with high efficiency, thereby suppressing abnormal heating of the winding 3 when current is applied. However, having a portion of the winding 3 exposed makes it difficult to stabilize the shape during winding. In contrast, in this embodiment, the winding guide portion 12A is provided along the circumferential direction of the first turn of the winding 3, preventing the winding 3 from collapsing, while also achieving high-efficiency heat dissipation performance.

[0032] [supplementary explanation] The coil device 1 according to the embodiment of the present invention and the bobbin 10 used therein have been described above, but it goes without saying that the present invention can be embodied in various forms without departing from the spirit of the present invention.

[0033] (First modified example of bobbin) For example, in the above embodiment, the upper flange 14 and the lower flange 16 of the bobbin 10 are respectively provided with a pair of upper wall portions 26 and a pair of lower wall portions 30, but the present invention is not limited to this. For example, as in a bobbin 50 according to a first modified example shown in FIG. 8, only a wall portion having a winding pull-out portion 40 may be formed at the end of the flange. Hereinafter, the bobbin 50 according to the first modified example will be described with reference to FIG. 8. Note that the same components as those in the above embodiment are designated by the same reference numerals, and description thereof will be omitted.

[0034] The bobbin 50 according to the first modified example has a cylindrical tube portion 52 around which the winding 3 is wound, and an upper flange 54 and a lower flange 56 formed on both axial sides of the tube portion 52. A winding guide portion 52A that protrudes radially outward from the outer circumferential surface of the tube portion 52 is provided at the rear end of the tube portion 52. This winding guide portion 52A has a configuration that corresponds to the winding guide portion 12A of the above embodiment. A lower wall portion 58 is provided at the rear end of the lower flange 56 and extends to one axial side of the tube portion 52 (the downward side in FIG. 8 ), and a winding lead-out portion 40 consisting of a first groove 42 and a second groove 44 is formed on the surface of the lower wall portion 58. The configurations of the tubular portion 52, upper flange portion 54, lower flange portion 56, and lower wall portion 58 are similar to the configurations of the tubular portion 12, upper flange portion 14, lower flange portion 16, and lower wall portion 30 of the above embodiment, and therefore detailed description thereof will be omitted. The bobbin 50 having this configuration also basically follows the configuration of the bobbin 10, and therefore can obtain the same actions and effects as the above embodiment.

[0035] (Second modified bobbin) Furthermore, in the above embodiment, two cores (first core 2A and second core 2B) are attached to the outside of the bobbin 10, but the present invention is not limited to this. For example, a configuration in which one core is attached may be used, as in the bobbin 60 according to the second modified example shown in FIG. 9. Hereinafter, the bobbin 60 according to the second modified example will be described with reference to FIG. 9. Note that the same components as those in the above embodiment are designated by the same reference numerals, and description thereof will be omitted.

[0036] The bobbin 60 according to the second modification includes a cylindrical tube portion 62 having an axial direction extending vertically, and an upper flange 64 and a lower flange 66 formed on both axial sides of the tube portion 62. A winding guide portion 62A is provided at the rear end of the tube portion 62, protruding radially outward from the outer circumferential surface of the tube portion 62. This winding guide portion 62A corresponds to the winding guide portion 12A of the above embodiment. A pair of upper wall portions 68 are formed on the upper surface of the upper flange portion 64, extending upward from both front-rear end portions. The pair of upper wall portions 68 can support the side surfaces of one upper core 21 located above the upper flange portion 64 from both front and rear sides. A pair of lower wall portions 70 are formed on the lower surface of the lower flange portion 66, extending downward from both front-rear end portions. The pair of lower wall portions 70 can support the side surfaces of one lower core 22 located below the lower flange portion 66 from both front and rear sides. Furthermore, a lower wall portion 70 extending downward from the rear end of the lower flange 66 is formed with a winding lead-out portion 40 consisting of a first groove portion 42 and a second groove portion 44. The configurations of the tubular portion 62, upper flange portion 64, lower flange portion 66, upper wall portion 68, and lower wall portion 70 are similar to the configurations of the tubular portion 12, upper flange portion 14, lower flange portion 16, upper wall portion 26, and lower wall portion 30 of the above embodiment, and therefore detailed description thereof will be omitted. The bobbin 60 having this configuration also basically follows the configuration of the bobbin 10, and therefore can obtain the same functions and effects as the above embodiment.

[0037] (Third modified bobbin) Furthermore, since the bobbin 10 in the above embodiment is configured to be used in the coil device 1 as a choke coil, the bobbin 10 has been described as having one winding 3 wound thereon, but the present invention is not limited to this. For example, a bobbin 80 according to a third modified example shown in FIGS. 10 and 11 may have two windings wound thereon. Hereinafter, the bobbin 80 according to the third modified example will be described with reference to FIGS. 10 and 11. Note that the same components as those in the above embodiment will be assigned the same reference numerals and their description will be omitted.

[0038] Fig. 10 shows a side view of the bobbin 80 as seen from the right side. Fig. 11(A) shows a side view of the bobbin 80 as seen from the front side, and Fig. 11(B) shows a side view of the bobbin 80 as seen from the rear side. As shown in these figures, the bobbin 80 according to the third modification has a middle flange 92 between an upper flange 84 and a lower flange 86, and differs from the above embodiment in that it is configured so that two windings 301, 302 can be arranged on either side of the middle flange 92. The other configurations are the same as those of the above embodiment.

[0039] The bobbin 80 has a cylindrical tube portion 82 whose axial direction is the up-down direction, and an upper flange portion 84 and a lower flange portion 86 formed on both axial sides of the tube portion 82. A pair of upper wall portions 88 extending upward from both front-rear end portions are formed on the upper surface of the upper flange portion 84, and the pair of upper wall portions 88 support the side surfaces of the upper core 21 of the first and second cores 2A, 2B attached to the bobbin 80 from both front and rear sides. In addition, a pair of lower wall portions 90 extending downward from both front-rear end portions are formed on the lower surface of the lower flange portion 86, and the pair of lower wall portions 90 support the side surfaces of the lower core 22 of the first and second cores 2A, 2B from both front and rear sides. The configurations of the tubular portion 82, upper flange portion 84, lower flange portion 86, upper wall portion 88 and lower wall portion 90 are similar to the configurations of the tubular portion 12, upper flange portion 14, lower flange portion 16, upper wall portion 26 and lower wall portion 30 in the above embodiment, so detailed explanations will be omitted.

[0040] Here, a center flange 92 protruding from the outer peripheral surface of the cylindrical portion 82 is disposed between the upper flange 84 and the lower flange 86. The center flange 92 protrudes radially outward in a flange-like shape from the axial middle of the outer peripheral surface of the cylindrical portion 82, and is a plate-like member formed into a substantially rectangular shape in a plan view. The front and rear ends of the center flange 92 protrude outward from an upper wall 88 of the upper flange 84 and a lower wall 90 of the lower flange 86 to ensure insulation between the two windings 301, 302 wound around both sides of the center flange 92 and the lead wires drawn from the ends of the windings 301, 302. The center flange 92 divides the space between the upper flange 84 and the lower flange 86 into two sections S1, S2 along the axial direction.

[0041] 11(A), a first winding 301 is disposed in section S1 above the center flange 92. The first winding 301 is spirally wound around the tubular portion 82 between the upper flange 84 and the center flange 92. An end portion 301A of the first winding 301, pulled out from a winding start portion 301B, is pulled out axially upward of the tubular portion 82 by a first winding pull-out portion 110. The first winding pull-out portion 110 is formed on the upper wall portion 88 extending from the front end portion of the upper flange 84.

[0042] 11(B), a second winding 302 is disposed in section S2 below the center flange 92. The second winding 302 is spirally wound around the tubular portion 82 between the lower flange 86 and the center flange 92. An end portion 302A of the second winding 302, pulled out from a winding start portion 302B, is pulled out axially downward from the tubular portion 82 by a second winding pull-out portion 130. The second winding pull-out portion 130 is formed on the lower wall portion 90 extending from the rear end portion of the lower flange 86.

[0043] Additionally, each of the two sections S1 and S2 is provided with a winding guide portion 82A, 82B that is provided along the circumferential direction of the first turn of the first and second windings 301, 302. The two winding guide portions 82A, 82B are provided in each of the two sections S1 and S2, protruding radially outward from the front end portion or the rear end portion of the tubular portion 82. The configuration of the two winding guide portions 82A, 82B corresponds to the configuration of the winding guide portion 12A in the above embodiment.

[0044] The first and second winding lead-out portions 110, 130 will now be described in detail. The first winding lead-out portion 110 is formed on the upper wall portion 88, which extends upward from the end of the upper flange portion 84 (the front end in FIG. 11A), and a winding start end 301A of the first winding 301 is led out through the first winding lead-out portion 110. The first winding lead-out portion 110 is composed of a first groove 112 that is inclined upward from the undersurface of the upper flange portion 84 (one axial side of the cylindrical portion 82), and a second groove 44 that extends from the first groove 112 toward the radially outer side of the cylindrical portion 82 and reaches the end of the upper wall portion 88. The end 301A of the first winding 301, led out from the winding start 301B of the first turn, is guided by the first groove 112 and the second groove 114 and led out axially upward of the cylindrical portion 82 relative to the second turn. As a result, only the spiral first winding 301 is housed in the section S1 formed between the upper flange 84 and the middle flange 92.

[0045] The second winding 302 is formed on the lower wall 90, which extends downward from the end of the lower flange 86 (the rear end in FIG. 11(B)), and a winding start end 302A of the second winding 302 is drawn out by the second winding draw-out portion 130. The configuration of this second winding draw-out portion 130 is similar to the configuration of the winding draw-out portion 40 of the above embodiment, so a detailed description will be omitted. The end 302A of the second winding 302 drawn out from the winding start 302B of the first turn is guided by the first groove 132 and the second groove 134, and drawn out axially downward of the tubular portion 82 relative to the second turn. As a result, only the spiral second winding 302 is accommodated in the section S2 formed between the lower flange 86 and the center flange 92.

[0046] The bobbin 80 having the above configuration basically follows the configuration of the bobbin 10 according to the above embodiment, and therefore can achieve the same functions and effects. Furthermore, with the bobbin 80 having the above configuration, two windings, consisting of the first winding 301 and the second winding 302, can be wound around one bobbin 80, making it possible to configure a bobbin that configures a coil device as a transformer having a primary winding and a secondary winding. Furthermore, because the lead wires of the first winding 301 and the second winding 302 can be drawn out to the front and rear sides of the bobbin 80, circuit components connected to the primary winding of the transformer and circuit components connected to the secondary winding can be arranged separately at the front and rear of the bobbin 80, facilitating assembly.

[0047] However, the present invention is not limited to this, and the first and second winding lead-out portions 110, 130 may be formed on the upper wall portion 88 and the lower wall portion 90, respectively, at the front end or rear end of the bobbin 80. In other words, the lead-out wires of the primary winding and secondary winding of the transformer may be led out from one side of the bobbin 80.

[0048] (Modification of the winding guide portion) In the above embodiment and each modified example, the wire guide portion is configured to be formed integrally with the cylindrical portion, but the present invention is not limited to this. The wire guide portion may be configured to be provided along the circumferential direction of the first turn of the winding 3 at a position separated from the cylindrical portion 12, as in the winding guide portion 140 according to a first modified example shown in Fig. 12(A) and the winding guide portion 140 according to a second modified example shown in Fig. 12(B).

[0049] The winding guide portion 140 according to the first modified example shown in FIG. 12(A) is arranged at a distance radially outward from the tubular portion 12, and is formed in a cylindrical shape protruding from the lower surface of the upper flange portion 14 or the lower surface of the lower flange portion 16 along the axial direction of the tubular portion 12.

[0050] 12(B) shows a second modified example of a winding guide 150 that is configured by a wall disposed at a distance from the radially outer side of the cylindrical portion 12. This winding guide 150 protrudes from the lower surface of the upper flange 14 or the lower surface of the lower flange 16 along the axial direction of the cylindrical portion 12, and has an arc shape that curves along the circumferential direction of the first turn of the winding 3.

[0051] In the above embodiment, the winding lead-out portion 40 is formed on the lower wall portion 30. However, the present invention is not limited to this, and the winding lead-out portion 40 may be formed on the upper wall portion 26, as in the first winding lead-out portion 110 according to the third modified example.

[0052] In the above embodiment, a Litz wire is used as the wire material for the winding 3, but the present invention is not limited to this and a solid wire may also be used. [Explanation of symbols]

[0053] 1 Coil device 2 cores 3 windings 3A End of the first winding 3B Beginning of the first winding 10 bobbins 12 Cylinder part 12A Winding guide 14 Upper Tsuba (Tsuba) 16 Lower Tsuba (Tsuba) 30 Lower wall (wall) 40 Winding lead-out section 42 First groove 44 Second groove

Claims

[Claim 1] a bobbin having a cylindrical portion and two flange portions formed on both sides of the cylindrical portion in the axial direction; a winding wound around the cylindrical portion; a core having a center leg portion inserted into the cylindrical portion, the bobbin has the winding wound spirally around the cylindrical portion between the two flange portions, and has a winding guide portion that supports the winding; the two flanges are provided at positions corresponding to the winding diameter of the winding, the axial length of the center leg portion, which is the internal height of the core, is determined by the two flange portions and the height of one winding diameter of the winding, The coil device, wherein the winding starts at an outer side of the middle leg portion of the core.

Images