JP7751985B2 - Coil Device - Google Patents

Description

The present invention relates to a coil device.

Conventionally, in coil devices such as transformers and chokes, insulating materials are placed around the windings to prevent short circuits inside the device and to electrically protect the windings from peripheral mounted components. Therefore, when a heat dissipation member is provided to dissipate heat generated by the windings, the heat dissipation member is often attached to the windings via multiple insulating members.

For example, Patent Document 1 below discloses a structure in which a transformer having primary and secondary windings is housed in a metal case to dissipate heat generated by the transformer. In this transformer, the windings are wound around an insulating resin bobbin, and the bobbin, integrated with the core, is housed in a metal case, which serves as a heat dissipation member. The case is filled with a resin filler to ensure insulation between the windings (and core) and the case. As a result, heat radiated from the surfaces of the windings and core is transferred to the case via the filler, and is then dissipated to the outside by cooling pipes and heat sinks attached to the case.

Japanese Patent Application Laid-Open No. 2019-041065

In the above-mentioned Patent Document 1, a heat dissipation path is formed by attaching multiple components to the outside of the bobbin, which complicates the process of mounting the bobbin (coil device) to a fixed object. Furthermore, because the multiple components that make up the heat dissipation path increase the external size of the device, it becomes difficult to ensure a heat dissipation path in a position that does not interfere with surrounding mounted components.

The present invention has been made to solve the above-mentioned problems, and aims to provide a coil device that can be easily mounted on an object to be fixed and that can ensure a heat dissipation path in a position that does not interfere with surrounding mounted components.

The bobbin according to the first aspect of the present invention is a bobbin that is fixed to a fixed object with a winding wound thereon, and includes a base portion that is fixed to the fixed object, and a cylindrical portion that is connected to the base portion and around which the winding is wound, and the base portion has through holes that allow heat generated by the winding wound around the cylindrical portion to be dissipated to the fixed object.

The bobbin according to the present invention has a base connected to the cylindrical portion around which the winding is wound, and the bobbin is fixed to a fixed object via the base. The base has through holes, through which heat generated by the winding can be dissipated to the fixed object. Therefore, the bobbin itself can be formed with through holes that serve as a heat dissipation path, and the bobbin can be fixed to a fixed object, simplifying the process of mounting the bobbin to the fixed object. Furthermore, because the heat dissipation path is located within the area inside the through holes formed in the base, it can be ensured in a position that does not interfere with surrounding mounted components.

FIG. 1 is a perspective view of a coil device according to a first embodiment. 2 is a cross-sectional view of the coil device taken along line II-II in FIG. 1. FIG. 2 is an exploded perspective view of the coil device according to the first embodiment. FIG. 2 is a perspective view of a winding according to the first embodiment. FIG. 2 is a planar perspective view of the bobbin according to the first embodiment. FIG. 2 is a bottom perspective view of the bobbin according to the first embodiment. FIG. 2 is a front view of the bobbin according to the first embodiment. FIG. 10 is an exploded perspective view of a bobbin and a heat transfer member of a coil device according to a second embodiment. FIG. 10 is a side perspective view of a bobbin according to a second embodiment. FIG. 4 is a cross-sectional view corresponding to FIG. 2 and showing a coil device according to a second embodiment. FIG. 11 is an exploded perspective view of a bobbin and a heat transfer member of a coil device according to a third embodiment. FIG. 10 is a cross-sectional view corresponding to FIG. 2 and showing a coil device according to a third embodiment.

A coil device 1 according to a first embodiment of the present invention and a bobbin 3 used in the coil device 1 will be described below with reference to Figures 1 to 7. For ease of explanation, in this embodiment, 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. Furthermore, in each figure, some reference numerals may be omitted to make the drawings easier to understand.

As shown in Figures 1 and 2, the coil device 1 of this embodiment constitutes, as an example, a choke coil. The coil device 1 includes a core 2 formed of a magnetic material such as a ferrite core, a bobbin 3 through which the core 2 is inserted, and a winding 4 wound around the bobbin 3. The coil device 1 is housed in a box-shaped case 5 that is open on the upper side, and is fixed to the bottom wall 5A of the case 5 using screws 54. The case 5 is made of a metal material with high heat dissipation properties, such as aluminum.

As shown in FIG. 3 , the core 2 is composed of a first core 21 that forms the lower portion of the core 2 and a second core 22 that forms the upper portion of the core 2. The first core 21 and the second core 22 are molded separately and joined together by overlapping them so that they sandwich the bobbin 3 from above and below. The first core 21 has a core side portion 211, a middle leg portion 212, and an outer leg portion 213, and its top, bottom, left, and right cross section is approximately E-shaped. The core side portion 211 has a predetermined thickness in the vertical direction and is formed as a plate that is long in the horizontal direction. The middle leg portion 212 is formed as a cylinder with its axial direction extending vertically and extending upward (toward the second core 22) from the center of the core side portion 211. The outer leg portion 213 is formed as a vertical wall that has a predetermined thickness in the horizontal direction and extends upward from both left and right ends of the core side portion 211. The opposing side surfaces of the pair of outer legs 213 are curved surfaces that are curved in an arc. When the first core 21 is attached to the bobbin 3, the core side portion 211 is positioned to cover the underside of the tubular portion 31 of the bobbin 3. The cylindrical center leg portion 212 is inserted into the tubular portion 31 of the bobbin 3, and the pair of outer leg portions 213 are positioned to cover the outer periphery of the tubular portion 31 from both the left and right sides.

The second core 22 has a predetermined thickness in the vertical direction and is formed as a long plate in the horizontal direction, with a generally I-shaped cross section. When attached to the bobbin 3, the second core 22 is placed above the first core 21 and covers the upper surface of the cylindrical portion 31. After being placed one above the other, the first core 21 and second core 22 are joined together by wrapping them with exterior tape (insulating tape) (not shown). This forms a closed magnetic circuit of the choke coil by the first core 21 and second core 22.

The core 2 described above has core openings 23 that open the internal space formed by the first core 21 and second core 22 to both the front and rear. As shown in FIG. 1, when the core 2 is attached to the bobbin 3, a portion of the winding 4 wound around the tubular portion 31 of the bobbin 3 is exposed to the outside of the core 2 through the core openings 23 on both the front and rear sides. Furthermore, ends 4A and 4B of the winding 4 are pulled out from the front core opening 23. Furthermore, below the winding 4, a base portion 38 of the bobbin 3 connected to the tubular portion 31 protrudes from the core openings 23 on both the front and rear sides.

As shown in Figures 5 to 7, the bobbin 3 has a cylindrical portion 31 and a base portion 38 connected to the cylindrical portion 31. The cylindrical portion 31 of the bobbin 3 is integrally formed with an upper flange portion 32, a lower flange portion 34, and a separator portion 36. The bobbin 3 is formed, for example, by integral molding using an insulating resin material.

The tubular portion 31 is formed in a cylindrical shape with its axis extending vertically. The center leg portion 212 of the cylindrical first core 21 can be inserted into the interior of the tubular portion 31. An upper flange 32 protrudes radially outward from the outer surface of the tubular portion 31 at the upper end of the tubular portion 31. The upper flange 32 has a first plate portion 321 and a second plate portion 322 protruding radially outward from the outer surface of both the left and right sides of the tubular portion 31. The first plate portion 321 and the second plate portion 322 are each plate-shaped members having a constant width in the radial direction and a constant thickness in the axial direction, and are formed in a fan shape in a plan view. As shown in FIG. 3 , the second core 22 is placed on the upper surface of the upper flange 32, which is made up of the first plate portion 321 and the second plate portion 322. Furthermore, a pair of front and rear support walls 323 are provided on the upper surface of the upper flange 32, extending upward from both the front and rear ends. The second core 22 can be inserted between the pair of support walls 323. That is, the pair of support walls 323 are configured to support the side surfaces of the second core 22, which is placed on the upper flange 32, from both front and rear sides. Because the pair of support walls 323 support the second core 22, a gap material can be inserted and held between the upper flange 32 and the second core 22. In this embodiment, a gap material 6 is inserted between the upper flange 32 and the second core 22. For example, the gap material 6 is a resin sheet material made of polycarbonate or the like. While inserting the gap material 6 between the upper flange 32 and the second core 22 is not required, if the gap material 6 is inserted, the thickness of the gap material 6 can be adjusted to create a desired gap between the first core 21 and the second core 22. This allows for adjustment of the inductance of the coil device 1. If the gap material 6 is not used, the center leg 212 can be polished to form a gap.

As shown in FIG. 6 , a lower flange 34 is provided at the lower end of the cylindrical portion 31, protruding radially outward from the outer peripheral surface of the cylindrical portion 31. The lower flange 34 has a first plate portion 341 and a second plate portion 342 that protrude radially outward from the outer peripheral surface of the cylindrical portion 31 on both the left and right sides. The first plate portion 341 and the second plate portion 342 are each plate-shaped members having a constant width in the radial direction and a constant thickness in the axial direction, and are formed in a fan shape in a plan view. As shown in FIG. 3 , the core side portion 211 of the first core 21 is placed on the underside of the lower flange 34, which is made up of the first plate portion 341 and the second plate portion 342. Furthermore, a pair of front and rear support walls 343 are provided on the underside of the lower flange 34, extending downward from both the front and rear ends. The core side portion 211 of the first core 21 can be inserted between the pair of support walls 343. In other words, the pair of support walls 343 are configured to support the side surfaces of the first core 21, which are located below the lower flange 34, from both front and rear sides. With the above configuration, the pair of support walls 343 are connected to the lower end of the tubular portion 31 and form part of the base portion 38, which will be described later.

As shown in Figures 2 and 7, a separator portion 36 protruding radially outward from the outer circumferential surface of the cylindrical portion 31 is provided in the vertically intermediate portion of the cylindrical portion 31. The separator portion 36 is a plate-shaped member having a constant width in the radial direction and a constant thickness in the axial direction. This separator portion 36 extends circumferentially around the cylindrical portion 31, dividing the cylindrical portion 31 into two vertical (axial) sections S1 and S2. The winding portions of the winding 4 can be wound around the lower section S1 and the upper section S2 of the cylindrical portion 31, respectively, which are divided by the separator portion 36. The axial height of the sections S1 and S2 is set to be the same as or equivalent to the diameter of the wire constituting the winding 4. Therefore, by inserting and winding the winding 4 into each section S1 and S2, the winding 4 can be easily formed into a spiral shape in plan view. Furthermore, the separator portion 36 is formed in a roughly C-shape in plan view, with the opening of the C serving as an opening 37 that connects the lower section S1 and the upper section S2. This opening 37 can also be described as a groove that penetrates the separator portion 36 in the thickness direction and opens to the front. The radial depth of the opening 37 is the same as the radial width of the separator portion 36, and has a depth that extends from the outer edge of the separator portion 36 to the outer peripheral surface of the tubular portion 31. Forming the opening 37 with the above configuration in the separator portion 36 makes it possible to wind a two-layered winding, such as the winding 4 of this embodiment, around the tubular portion 31.

Specifically, as shown in FIG. 4, the winding 4 is a litz wire made by twisting together multiple wire rods (thin wires) and is formed by alpha winding the litz wire. The winding 4 formed by alpha winding has two winding sections 41, 42 spaced apart in the axial direction. Note that the winding 4 is not limited to litz wire; solid wire can also be used. However, when the coil device 1 is incorporated into a high-frequency circuit that supplies high-power, high-frequency power, such as a contactless charging system for electric vehicles such as electric vehicles and plug-in hybrid vehicles, forming the winding 4 from litz wire is advantageous in that it can suppress increases in winding resistance due to the skin effect.

To alpha-wind the winding 4 around the tubular portion 31, first, the intermediate portion 4C (the midpoint of the winding 4) in the direction of extension of the winding 4 is passed through the opening 37 of the separator portion 36. Then, the portion below the intermediate portion 4C inserted in section S1 is spirally wound around the outer circumferential surface of the tubular portion 31 on the underside of the separator portion 36. Meanwhile, the portion above the intermediate portion 4C inserted in section S2 is spirally wound around the outer circumferential surface of the tubular portion 31 on the upper side of the separator portion 36. This allows the formation of a two-layer winding 4 with a first winding portion 41 and a second winding portion 42 formed in a spiral shape on both axial sides of the separator portion 36. With the core 2 attached to the tubular portion 31, the opening 37 of the separator portion 36 is positioned facing the front core opening 23, and the ends 4A and 4B of the winding 4, which intersect on the front side of the opening 37, are pulled out to the outside of the core 2 through the core opening 23 (see Figure 1). After the winding 4 is wound around the tubular portion 31, the outer surface is covered with an exterior tape (insulating tape) not shown. Note that the exterior tape can be omitted if the winding 4 itself has a fusion layer, or if the shape of the winding 4 is maintained.

As shown in Figures 5 to 7, the bobbin 3 has a base portion 38 connected to the lower end of the tubular portion 31. The base portion 38 is frame-shaped overall, and has a first frame portion 38A and a second frame portion 38B that protrude horizontally from the outer peripheral surface of the tubular portion 31 on both the front and rear sides. Since the first frame portion 38A and the second frame portion 38B have the same shape and size, the following description will focus on the first frame portion 38A that protrudes forward from the tubular portion 31.

The first frame portion 38A is composed of one support wall portion 343 (the front side in Figures 5 and 6) connected to the lower end of the tubular portion 31, an outer wall portion 381 arranged outside the support wall portion 343, and a pair of base portion-side boss portions 382 connecting the opposite ends of the support wall portion 343. As described above, the support wall portion 343 of the first frame portion 38A protrudes downward from the front end of the lower flange portion 34 provided at the lower end of the tubular portion 31 and has a predetermined plate thickness in the front-to-rear direction. The support wall portion 343 is formed in a V-shape in plan view that opens to the outside of the bobbin (the front side in Figures 5 and 6). The outer wall portion 381 extends in the left-right direction so as to close the V-shaped opening of the support wall portion 343 and has a predetermined plate thickness in the front-to-rear direction. The base-side boss 382, which connects the ends of the support wall 343 and the outer wall 381, is cylindrical and has an axial direction extending vertically. The support wall 343, outer wall 381, and pair of base-side bosses 382 configured as described above form the first frame 38A in a generally trapezoidal frame shape in plan view. Therefore, the first frame 38A has a through-hole H that penetrates the base 38 in the vertical direction. In this embodiment, to improve the strength of the first frame 38A, two reinforcing beams 383 extending in the front-rear direction are installed parallel to each other between the support wall 343 and the outer wall 381. The second frame 38B is provided at the lower end of the tubular portion 31, protruding from the opposite side of the first frame 38A. As described above, the second frame 38B is configured similarly to the first frame 38A, and therefore will not be described in detail.

As shown in FIG. 1, the base portion 38 is fixed to the bottom wall 5A of the case 5 via four base portion-side bosses 382 provided on the first frame portion 38A and the second frame portion 38B. The bottom wall 5A of the case 5 is provided with four cylindrical case side bosses 51 that protrude upward from the upper surface of the bottom wall 5A. The four case side bosses 51 correspond to the four base portion side bosses 382. A screw 54 is inserted into each base portion side boss 382 with the case side boss 51 inserted inside. The screw 54 is inserted into a screw hole (female thread) formed in the case side boss 51 and threadedly engages, thereby fixing the base portion 38 to the case 5. With the base portion 38 of the bobbin 3 fixed to the case 5 in this manner, a portion of the lower first winding portion 41 of the winding 4 wound around the cylindrical portion 31 of the bobbin 3 is positioned so as to cover the first frame portion 38A and the second frame portion 38B from above. In other words, a portion of the first winding portion 41 and a portion of the second winding portion 42 are positioned above the through holes H of the first frame portion 38A and the second frame portion 38B. That is, as shown in FIG. 2, the through holes H of the first frame portion 38A and the second frame portion 38B connect the axial surface of the first winding portion 41 (the lower surface in FIG. 2) to the bottom wall 5A of the case 5.

When the coil device 1 is in operation (conduction), the winding 4 generates heat. The heat from the surface of the first winding portion 41 is transferred to the bottom wall of the case 5 through the through-holes H in the first frame portion 38A and the second frame portion 38B and dissipated from the case 5 to the outside (see the arrows in Figure 2). In this way, the bobbin 3 can form a heat dissipation path for dissipating heat generated by the winding 4 to the case 5 by utilizing the area inside the through-holes H. To further improve the heat dissipation efficiency of this heat dissipation path, it is preferable to insert a heat transfer material with high thermal conductivity inside the through-holes H. In this embodiment, a thermally conductive filler is added to the potting resin P filled inside the case 5 to form the heat transfer material. As shown schematically in Figure 2, when the potting resin P is filled inside the case 5, the potting resin P also fills the space between the base portion 38 and the bottom wall 5A and the through-holes H in the first frame portion 38A and the second frame portion 38B. The potting resin P filled into the through holes H in this way constitutes a heat transfer member that transfers heat generated by the winding 4 to the case 5. Furthermore, because the base portion 38 of this embodiment forms a frame as a whole, it is possible to prevent air bubbles from remaining on the underside of the base portion 38 after the potting resin P is filled. This also improves the heat dissipation efficiency of the heat dissipation path.

(Action and effect)
As described above, according to the coil device 1 of the first embodiment of the present invention, the bobbin 3 is provided with a base portion 38 connected to the cylindrical portion 31 around which the winding 4 is wound, and the bobbin 3 is fixed to the bottom wall 5A of the case 5 via the base portion 38. The base portion 38 has through holes H, through which heat generated in the winding 4 can be dissipated to the case 5 (bottom wall 5A). Therefore, the through holes H that serve as heat dissipation paths can be formed in the bobbin 3 itself and the bobbin 3 can be fixed to the case 5, which simplifies the mounting process of mounting the bobbin 3 in the case 5. Furthermore, because the heat dissipation path is located within the region inside the through holes H formed in the base portion 38, the heat dissipation path can be secured in a position that does not interfere with surrounding mounted components.

Furthermore, the through-hole H in this embodiment is configured to expose a portion of the winding 4 to the bottom wall 5A of the case 5, allowing communication between the winding 4 and the bottom wall 5A. Therefore, heat generated by the winding 4 can be efficiently dissipated to the case 5.

Furthermore, the through holes H in this embodiment connect the axially facing surface of the winding 4 to the bottom wall 5A of the case 5. Therefore, in addition to the radially outer portion of the winding 4, heat can also be efficiently dissipated from the radially inner portion to the case 5.

Furthermore, the axial surface of the winding 4 is not covered with insulating exterior tape like the outer peripheral surface on the radially outer side. Therefore, the through holes H of this embodiment can form a heat dissipation path in the winding 4 at a position that avoids the exterior tape, so heat dissipation is not hindered by insulating materials such as exterior tape. As a result, the heat dissipation efficiency of the winding can be further improved.

Furthermore, with the bobbin 3 according to this embodiment, a heat transfer member that transfers heat generated by the winding 4 to the case 5 is inserted into the through-hole H. Specifically, the potting resin P filled inside the case 5 serves as the heat transfer member, and is inserted into the through-hole H. This further improves the heat dissipation efficiency of the heat dissipation path inside the through-hole H.

Furthermore, with the bobbin according to this embodiment, the second core 22 constituting the core 2 is placed on the upper flange 32 provided on the cylindrical portion 31, and the side surfaces of the second core 22 are supported from both sides by the support wall 323 provided on the upper flange 32. Therefore, the second core 22 is supported by the support wall 323, stably positioned relative to the bobbin 3, and the exterior tape that joins the core 2 can be easily wrapped around it. Furthermore, because the gap material 6 can be inserted between the upper flange 32 and the second core 22 and held by the support wall 323, it is easy to adjust the gap between the cores 2, and ultimately, the inductance of the coil device 1 can be easily adjusted.

The coil device 8 according to the second embodiment will now be described with reference to Figures 8 to 10. Components that are the same as those in the first embodiment described above are given the same reference numerals and their description will be omitted. The coil device 8 according to the second embodiment is characterized in that the heat transfer member inserted inside the through-hole H of the bobbin 81 is composed of a heat pipe 82. Correspondingly, the shape of the bobbin 81 is a partially modified version of the shape of the bobbin 3 in the first embodiment.

Specifically, in this embodiment, openings are formed in the separator portion 84 to allow two heat pipes 82 to pass through the respective through-holes H in the first frame portion 38A and the second frame portion 38B of the base portion 38. Therefore, the separator portion 84 of the bobbin 81 has a basic configuration similar to that of the separator portion 36 of the first embodiment, but differs in that, as shown in FIG. 9, openings 37, which were formed only on the front side of the separator portion 36 in the first embodiment, are formed on both the front and rear sides of the separator portion 84. The bobbin 81 also differs from the bobbin 3 of the first embodiment in that the two reinforcing beams 383 are not provided inside the through-holes H. The other configurations are the same as those of the first embodiment.

As shown in Figures 8 and 10, the heat pipe 82 is a thin tube with a sealed internal space. The refrigerant sealed in the internal space functions as a working fluid, transferring heat from one end (where the temperature is higher) to the other end (where the temperature is lower). One end of the heat pipe 82 is inserted inside the winding 4 wound around the tubular portion 31 of the bobbin 81. More specifically, the heat pipe 82 extends along the axial direction (vertical direction) of the winding 4, with one end of the heat pipe 82 inserted between the radially overlapping Litz wires in the first winding portion 41 and the second winding portion 42. The other end of the heat pipe 82 extends through the through-hole H toward the bottom wall 5A of the case 5 and is connected to a fixing plate 83 fixed to the bottom wall 5A. The fixing plate 83 is a plate-shaped member with a predetermined thickness in the vertical direction and is large enough to fit inside the through-hole H in a plan view. The fixing plate 83 is made of a metal such as aluminum with high thermal conductivity. The fixing plate 83 is fixed to the bottom wall 5A using two screws 86. The fixing plate 83 is not essential; the bottom wall 5A of the case 5 may have an insertion hole or the like provided therein, and the other end of the heat pipe 82 may be directly connected to the bottom wall 5A. Heat generated in the winding 4 is transferred to the heat pipe 82, which then moves it to the fixing plate 83 and bottom wall 5A. In the above configuration, one end of the heat pipe 82 is inserted into the gap between the windings 4, i.e., inside the windings 4, but the present invention is not limited to this. Any configuration is possible as long as one end of the heat pipe 82 is inserted inside the windings 4, and one end of the heat pipe 82 may be inserted between the tubular portion 31 of the bobbin 81 and the windings 4.

(Actions and Effects)
The coil device 8 having the above-described configuration basically follows the configuration of the coil device 1 according to the first embodiment, and therefore can obtain the same functions and effects.

In addition, in this embodiment, the heat transfer member that transfers heat generated in the winding 4 to the case 5 is composed of a heat pipe 82. Specifically, the heat pipe 82 extends through the through hole H toward the bottom wall 5A of the case 5, with one end inserted inside the first winding portion 41 and the second winding portion 42. This allows the heat pipe 82 to efficiently dissipate heat generated inside the winding 4 in the heat dissipation path within the through hole H. Furthermore, with the above configuration, even if the mounting portion of the coil device 8 is not inside a box-shaped case but on the surface of a flat die-cast plate or the like, a heat dissipation path can be formed in which a heat transfer member (heat pipe 82) is placed inside the through hole H.

The coil device 9 according to the third embodiment will now be described with reference to Figures 11 and 12. Components identical to those in the first embodiment described above are given the same reference numerals and their description will be omitted. The coil device 9 according to the third embodiment is characterized in that the heat transfer member inserted inside the through-hole H of the bobbin 91 is composed of a heat transfer plate 92 made of heat-dissipating resin. Correspondingly, the shape of the separator portion 94 of the bobbin 91 is similar to that of the bobbin 81 of the second embodiment. Furthermore, as in the second embodiment, the two reinforcing beams 383 are not provided inside the through-hole H. The other configuration of the coil device 9 is the same as that of the first embodiment described above.

The heat transfer plate 92 is formed by integral molding of a heat dissipation resin made of a resin material to which a thermally conductive filler has been added. The heat transfer plate 92 has an insertion portion 921 and a fixing portion 922, and is configured as a generally L-shaped plate overall. The insertion portion 921 extends in the axial direction of the winding 4 and has a predetermined thickness in the radial direction of the winding 4. The side of the insertion portion 921 is curved with a curvature equivalent to the circumferential curvature of the winding 4. One end of the insertion portion 921 is inserted between the radially overlapping Litz wires in the first winding portion 41 and the second winding portion 42. The other end of the insertion portion 921 extends through the through-hole H toward the bottom wall 5A of the case 5 and is connected to the fixing portion 922. The fixing portion 922 is a plate-shaped member with a predetermined thickness in the vertical direction and is large enough to cover the underside of the first frame portion 38A (or second frame portion 38B) of the base portion 38 of the bobbin 91 in a plan view. Fixing holes 93 are formed on both the left and right sides of the fixed portion 922, and are positioned coaxially with the base portion boss 382. Screws 54 that are inserted into the base portion boss 382 are inserted into the fixed portion 922, and the fixed portion 922 is fixed to the bottom wall 5A of the case 5 together with the base portion 38. Heat generated in the winding 4 is transferred to the heat transfer plate 92 and then moved to the bottom wall 5A by the heat transfer plate 92. Note that in the above configuration, one end of the insertion portion 921 is inserted into the gap between the winding 4, i.e., inside the winding 4, but the present invention is not limited to this. Any configuration is possible as long as one end of the insertion portion 921 is inserted inside the winding 4, and one end of the insertion portion 921 may be inserted between the tubular portion 31 of the bobbin 91 and the winding 4.

(Actions and Effects)
The coil device 9 having the above-described configuration basically follows the configuration of the coil device 1 according to the first embodiment, and therefore can obtain the same functions and effects.

In this embodiment, the heat transfer member that transfers heat generated by the windings 4 to the case 5 is a heat transfer plate 92 made of heat dissipation resin. The heat transfer plate 92 has an insertion portion 921 that extends through the through hole H toward the bottom wall 5A of the case 5, and a fixed portion 922 that is connected to the insertion portion 921. Because the tip of this insertion portion 921 is inserted inside the windings 4, heat generated inside the windings 4 is transferred to the fixed portion 922 and dissipated to the bottom wall 5A via the fixed portion 922. This allows the heat generated inside the windings 4 to be efficiently dissipated by the heat transfer plate 92 along the heat dissipation path within the through hole H. Furthermore, with the above configuration, even if the mounting portion of the coil device 9 is not inside a box-shaped case but on the surface of a flat die-cast plate or the like, a heat dissipation path can be formed in which a heat transfer member (heat transfer plate 92) is disposed inside the through hole H.

[supplementary explanation]
The present invention is not limited to the above-described embodiments, and various modifications, applications, and combinations of configurations are possible without departing from the spirit of the present invention.

In addition, in each of the above embodiments, a single separator portion 36, 84, 94 is provided on the cylindrical portion 31 of the bobbin 3, 81, 91, but the present invention is not limited to this. The cylindrical portion of the bobbin may be provided with multiple separator portions lined up in the axial direction. Alternatively, the cylindrical portion of the bobbin may not be provided with any separator portions. In each of the above embodiments, the axial height dimension of the sections S1, S2 separated by the separator portions 36, 84, 94 is set to be equal to the coil diameter, but the present invention is not limited to this, and the axial height of each section S1 can be changed as appropriate for each section.

In the above embodiment, the choke coil is configured using a coil device, but the present invention is not limited to this. For example, a transformer may be configured by winding a primary winding around one or more of the multiple sections defined by separator sections 36, 84, and 94 in the cylindrical section 31, and winding a secondary winding around another section.

In the above embodiment, the winding 4 wound around the cylindrical portion 31 is alpha wound, but the present invention is not limited to this. The winding method of the winding 4 can be changed as appropriate.

REFERENCE SIGNS LIST 1 Coil device 2 Core 3 Bobbin 5 Case (fixed object)
22 Core component (second core)
31 Cylinder part 32 Flange part (upper collar part)
38 Base portion 8 Coil device 81 Bobbin 82 Heat pipe (heat transfer member)
9 Coil device 91 Bobbin 92 Heat transfer plate (heat transfer member)
921 Insertion part 922 Fixation part H Through hole P Potting resin (heat transfer member)

Claims (5)

A coil device housed in a box-shaped case,
a bobbin including a cylindrically formed tubular portion and a base portion extending from a lower end of the tubular portion and fixed to a bottom wall of the case;
a winding wound around the outer peripheral surface of the cylindrical portion;
a potting resin filled in the case and having a thermally conductive filler added thereto;
and
The base portion has a through hole formed therein for dissipating heat generated by the winding to a fixed object side,
The potting resin is filled at least around the winding and in the through hole.
Coil device. A gap is provided between the base portion and the bottom wall of the case,
The coil device according to claim 1 , wherein the gap is filled with the potting resin. A coil device housed in a box-shaped case,
a bobbin including a cylindrically formed tubular portion and a base portion extending from a lower end of the tubular portion and fixed to a bottom wall of the case;
a winding made of a Litz wire wound around the outer peripheral surface of the cylindrical portion so as to overlap in the radial direction;
a heat pipe fixed to a bottom wall of the case;
and
The base portion has a through hole formed therein for dissipating heat generated by the winding to a fixed object side,
The heat pipe extends in the vertical direction, a lower end of the heat pipe is fixed to the bottom wall of the case, and an upper end of the heat pipe is inserted between the litz wires through the through hole.
Coil device. A coil device housed in a box-shaped case,
a bobbin including a cylindrically formed tubular portion and a base portion extending from a lower end of the tubular portion and fixed to a bottom wall of the case;
a winding made of a Litz wire wound around the outer peripheral surface of the cylindrical portion so as to overlap in the radial direction;
a heat transfer plate fixed to the bottom wall of the case;
and
The base portion has a through hole formed therein for dissipating heat generated by the winding to a fixed object side,
The heat transfer plate includes a fixed portion fixed to the bottom wall of the case together with the base portion, and an insertion portion erected from the fixed portion and inserted between the litz wires through the through hole.
Coil device. a flange portion provided on the cylindrical portion on the opposite side to the base portion,
5. The coil device according to claim 1, wherein the flange portion has support walls provided to support, from both sides, the side surfaces of the core component portion disposed on the flange portion.