JP2016100540A - choke coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a choke coil in which a distance between a coil and an installation object is unsusceptible to an influence of a formation error of a core.SOLUTION: A choke coil comprises: a coil including a wound portion that is formed by winding a winding wire; a columnar inner core that is housed in the wound portion; a bobbin including a cylindrical shape portion that is interposed between the wound portion and the inner core; a cylindrical shape outer core including a rectangular parallelepiped internal space that houses the inner core and the wound portion supported inside and outside the cylindrical shape portion, and forming a closed magnetic circuit together with the inner core; and a radiator layer that is interposed between the wound portion and an installation object, the bobbin including: a pair of flange-shaped portions that are extended from peripheries of both opening portions of the cylindrical shape portion and are interposed between an end face of the wound portion and an inner circumferential face of the outer core; and a base portion that is extended from peripheries of the flange-shaped portions in an axial direction of the cylindrical shape portion, and is interposed between an installation-side end face of the outer core facing the installation object and the installation object.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a choke coil used for various circuit components that perform boosting, power factor correction, current smoothing, and the like of a power supply circuit.

  There is a choke coil that includes a coil having a winding portion around which a winding is wound and a core in which the coil is arranged to form a closed magnetic circuit, as circuit components used for boosting a power supply circuit, power factor improvement, and the like. A choke coil typically uses a core formed by combining a pair of split core pieces called an EE type core or an ER type core. Patent Document 1 discloses a choke coil including a core that combines a columnar inner core and a rectangular frame-shaped outer core that accommodates the inner core as other cores. Both of the cores are powder magnetic cores obtained by compression-molding soft magnetic powder having an insulating coating.

  Patent Document 1 discloses a bobbin having a core (winding drum) around which a coil is wound, a columnar inner core housed in the winding drum, and a rectangular cylindrical outer core housing the bobbin and the inner core. The choke coil provided with the heat dissipation sheet interposed between the coil and the installation object is disclosed. The choke coil is attached to the installation target such that one end surface of the rectangular core-shaped end surfaces of the outer core is an installation surface on which the installation target is placed, and the other end surface (upper end surface) is opened. The bobbin extends from the winding drum and is interposed between the end face of the coil and the inner peripheral surface of the outer core, and extends from the flange in a direction parallel to the axis of the winding drum, A flat positioning portion that is locked to the upper end surface of the core is an integrated body. The bobbin winding drum is positioned with respect to the outer core by engaging the positioning portion of the bobbin with the upper end surface of the outer core. As a result, the inner core and the coil supported inside and outside the winding drum are positioned with respect to the outer core.

JP 2013-051402 A

  As described above, when the one end surface of the rectangular cylindrical outer core is used as the installation surface, there is a problem that the distance between the coil and the installation target varies due to molding errors of the core.

  If the outer core is a dust core as described above, there may be a large molding error. Due to this molding error, the height of the outer core, that is, the distance from one end surface to the other end surface of the rectangular frame shape changes. When the coil is positioned with respect to such an outer core, the position of the coil varies depending on the height of the outer core. As a result, when a choke coil having such an outer core is placed on the installation target, the distance between the coil and the installation target varies. As a result, the heat dissipation can vary.

  In order to correct the above-described variation in distance, for example, it is conceivable to prepare a large number of heat-dissipating sheets having different thicknesses and select them according to the distance. However, this measure leads to a decrease in industrial mass productivity due to an increase in time for selecting a heat dissipation sheet having an appropriate thickness. In addition, the cost increases.

  Alternatively, it is conceivable to prepare a heat dissipation layer that is thick to some extent, compress the heat dissipation layer, and absorb the above-described variation in distance depending on the amount of compression. However, this measure needs to adjust the amount of compression with high accuracy, resulting in a decrease in industrial mass productivity due to an increase in adjustment time.

  Therefore, an object of the present invention is to provide a choke coil in which the distance between the coil and the installation target is hardly affected by the molding error of the core.

A choke coil according to an aspect of the present invention includes a coil having a winding portion formed by winding a winding, a columnar inner core housed in the winding portion, and the winding portion and the inner core. A bobbin having a cylindrical portion interposed therebetween, a rectangular parallelepiped internal space for accommodating the inner core and the winding portion supported inside and outside the cylindrical portion, and a closed magnetic path together with the inner core A cylindrical outer core to be formed; and a heat dissipation layer interposed between the winding portion and the installation target.
The bobbins are respectively extended from peripheral edges of both openings of the cylindrical portion, and a pair of hook-shaped portions interposed between an end surface of the winding portion and an inner peripheral surface of the outer core, and A pedestal that extends from the periphery of the bowl-shaped portion along the axial direction of the cylindrical portion and is interposed between the installation-side end surface of the outer core that faces the installation target and the installation target. .

  According to the choke coil described above, the distance between the coil and the installation target is not easily affected by the core forming error.

1 is a schematic perspective view of a choke coil according to a first embodiment. FIG. 3 is a schematic perspective view of a bobbin provided in the choke coil according to the first embodiment. FIG. 3 is a partial vertical cross-sectional view of the choke coil according to Embodiment 1 cut along a (III)-(III) cutting line shown in FIG. 1. FIG. 3 is an exploded perspective view of the choke coil according to the first embodiment. In the choke coil of Embodiment 2 provided with a long heat dissipation layer, it is explanatory drawing explaining the arrangement | positioning state of a heat dissipation layer, and shows the state seen from the installation surface side. It is the fragmentary longitudinal cross-section which cut | disconnected the choke coil of Embodiment 2 provided with a long thermal radiation layer by the cross section parallel to the axial direction of a coil. It is the fragmentary longitudinal cross-section which cut | disconnected the choke coil of Embodiment 3 provided with the resin part in the cross section parallel to the axial direction of a coil. It is the fragmentary longitudinal cross-section which cut | disconnected the choke coil of Embodiment 4 provided with an insulating layer in the cross section parallel to the axial direction of a coil.

[Description of Embodiment of the Present Invention]
First, embodiments of the present invention will be listed and described.
(1) A choke coil according to an aspect of the present invention includes a coil having a winding part formed by winding a winding, a columnar inner core housed in the winding part, the winding part, and the inner part. A bobbin having a cylindrical portion interposed between the core, a rectangular parallelepiped internal space for accommodating the inner core and the winding portion supported inside and outside the cylindrical portion, and together with the inner core A cylindrical outer core that forms a closed magnetic path, and a heat dissipation layer interposed between the winding portion and the installation target are provided.
The bobbins are respectively extended from the peripheral edges of both openings of the cylindrical portion, and a pair of hook-shaped portions interposed between the end surface of the wound portion and the inner peripheral surface of the outer core, A pedestal portion that extends from the periphery of the bowl-shaped portion along the axial direction of the cylindrical portion and is interposed between the installation-side end surface of the outer core that faces the installation target and the installation target. .

  When the choke coil is placed on the installation target, the installation side end surface of the outer core does not contact the installation target, and the pedestal portion of the bobbin is supported by the installation target. Since the pedestal part is formed integrally with the cylindrical part that supports the winding part via the hook-shaped part, the position of the cylindrical part with respect to the installation target by placing the pedestal part on the installation target Is automatically determined, and the winding portion is also positioned with respect to the installation target. That is, the distance between the winding part of the coil and the installation target is substantially determined by the thickness of the pedestal part and does not substantially depend on the size of the outer core. Here, the bobbin can be manufactured by injection molding of an electrically insulating material such as resin. In a molding method such as injection molding, the molding error is small. For example, the molding error can be reduced to 1/2 or less, further 1/3 or less, and further 1/4 or less of the molding error of the dust core. As an example, the molding error of the green compact is ± 0.3 mm, and a maximum deviation of 0.6 mm may occur, whereas the molding error of the resin injection molded product is ± 0.1 mm, and further ± 0.05 mm. Can be about. As described above, the choke coil that supports the outer core with the bobbin with one surface of the bobbin having a very small forming error, that is, one surface of the pedestal portion, between the coil and the installation target regardless of the core forming error. The distance is difficult to vary and stable. Therefore, even when the choke coil uses a thin sheet as the heat dissipation layer, for example, the wound portion and the heat dissipation layer made of the thin sheet come into contact with each other and have excellent heat dissipation.

  (2) As an example of the choke coil, a form in which the bobbin is provided on the pedestal portion and includes a fixing portion that fixes the choke coil to the installation target.

  The above-described embodiment is easy without using a plate spring attachment (see FIG. 8 of Patent Document 1) or the like by placing the choke coil on the installation target and fastening a fastening member such as a bolt to the fixed portion. Can be installed. Therefore, the said form has few number of parts, and is excellent in installation workability | operativity.

  (3) As an example of the choke coil, there is a form in which the heat dissipation layer has an extended region that is disposed across the end surface of the winding portion and the inner peripheral surface of the outer core.

  In the above embodiment, since a part of the installation side end face of the outer core can contact the extended region of the heat dissipation layer, the outer core can be used as a heat dissipation path, and the heat dissipation is excellent. In particular, when the heat dissipation layer is made of an electrically insulating material such as a resin or a non-metallic inorganic material, the heat dissipation layer can be used as an insulating material between the coil and the installation target. In this case, since the extended region of the heat dissipation layer exists so as to block between the end face of the coil and the inner peripheral surface of the outer core, the creepage distance from the coil to the installation target can be secured sufficiently long, and the creeping discharge during this period can be prevented. Prevents and has excellent insulation. In this embodiment, the pedestal portion may be provided with its shape and size adjusted so as not to interfere with the extended region of the heat dissipation layer. For example, it can be set as the form provided with two base parts on both sides of an extension area | region so that an extension area | region may be pinched | interposed.

  (4) As an example of the choke coil, a form in which the bobbin is erected from the pedestal portion, is disposed to face the flange-shaped portion, and includes a wall portion that sandwiches the outer core with the flange-shaped portion. Can be mentioned.

  In the above configuration, the outer core is sandwiched between the hook-shaped portion and the wall portion, thereby restricting the movement of the outer core with respect to the bobbin so that the outer core can be positioned with high accuracy and the outer core can be held with the bobbin. Therefore, the said form is excellent in the position accuracy of the coil supported by a bobbin, and an inner core and an outer core.

  (5) As an example of the choke coil provided with the wall described in (4) above, a form in which the wall is provided with a notch that forms an edge corresponding to the opening edge of the cylindrical portion can be cited.

  In the above embodiment, the wall portion is provided with a notch, but the winding shaft of the winding machine forming the winding portion and the inner core can be inserted into the cylindrical portion through the notch, while having the wall portion. Therefore, the said form is excellent also in the formation workability | operativity of a coil, and the assembly workability | operativity of a choke coil.

  (6) As an example of the choke coil including the wall portion described in (4) or (5) above, the wall portion is thicker from the edge portion of the wall portion toward the pedestal portion side. The form provided with the introductory part inclined so that may be mentioned.

  In the above-described embodiment, the introduction portion is provided in the edge side region of the wall portion, so that the distance between the bowl-shaped portion and the wall portion is widened in the vicinity of the edge portion, and is narrowed on the pedestal portion side. I can say that. Therefore, although the said form has a wall part, an outer core can be easily inserted between a bowl-shaped part and a wall part, and it is excellent in assembly workability | operativity, and can hold | maintain an outer core firmly.

  (7) As an example of the choke coil including the wall portion described in (4) to (6) above, a resin that fixes the outer core interposed between the hook-shaped portion and the wall portion. The form provided with a part is mentioned.

  In the above configuration, the outer core can be firmly fixed between the bowl-shaped portion and the wall portion by the resin portion, and the coil, the inner core, the outer core, and the bobbin can be handled as an integrated object by this fixing. Therefore, the above-mentioned form is excellent in positional accuracy as described above, and it is easy to maintain the coil and the outer core at a predetermined position for a long time. Moreover, the said form is easy to handle the said integrated object in a manufacture process, and is excellent also in assembly workability | operativity.

  (8) As an example of the choke coil, an insulating layer that is interposed between the heat dissipation layer and the installation target and is disposed across the end surface of the winding part and the inner peripheral surface of the outer core is provided. A form is mentioned.

  Since the said form is equipped with an insulating layer between a coil and installation object, it is excellent in the insulation between both. In particular, in the above embodiment, since there is an insulating layer straddling between the end surface of the winding part and the inner peripheral surface of the outer core, the creeping surface from the coil to the installation target even when the heat dissipation layer is inferior in insulation. A sufficiently long distance can be secured to prevent creeping discharge during this period, and the insulation is excellent.

[Details of the embodiment of the present invention]
Hereinafter, specific examples of choke coils according to embodiments of the present invention will be described with reference to the drawings as appropriate. In the figure, the same name means the same thing.

[Embodiment 1]
The choke coil 1A according to the first embodiment will be described with reference to FIGS. The upper diagram of FIG. 1 illustrates a state where the choke coil 1A is placed on the installation target such that the lower surface of the choke coil 1A becomes the installation surface. In the following description, this state is described as an installation state. The lower diagram of FIG. 1 shows a case where the choke coil 1A in this installed state is viewed from the installation surface side. FIG. 3 shows a state in which the outer core 4 of the choke coil 1 </ b> A is cut in a cross section parallel to the axial direction of the coil 2.

Overall Configuration A choke coil 1 </ b> A according to Embodiment 1 includes a coil 2 having a winding part 20, a columnar inner core 3 housed in the winding part 20, and a cylindrical part 50 that supports the winding part 20. 5A, a cylindrical outer core 4 that forms a closed magnetic path together with the inner core 3, and a heat dissipation layer 6A interposed between the winding part 20 and the installation object 100 (FIG. 3). This choke coil 1A has one lower end surface 4d as an installation side end surface supported by the installation object 100 of the pair of frame-shaped end surfaces (upper end surface 4u, lower end surface 4d) provided in the outer core 4, and the other upper surface. It is mounted on an installation object 100 such as a cooling base so that the end face 4u is opened, and is used in a state of being fixed by a fastening member (not shown) such as a bolt or a screw. The choke coil 1A is supported by the bobbin 5A without the outer core 4 being directly supported by the installation target 100. Specifically, the outer core 4 is supported in a state where the outer core 4 is floated from the placement surface 100f (FIG. 3) of the installation target 100. One feature is that the bobbin 5A is molded as described above. Hereinafter, each element will be described in detail.

.. Coil The coil 2 has a winding part 20 formed by winding the winding 2w in a spiral shape, and a drawing part connected to an external device such as a power source that is connected to the winding part 20 and supplies power to the coil 2. (Part including the end of the winding 2w). The winding part 20 of this example is formed by winding the winding 2w in multiple layers, and has a rectangular tube shape in which the contour shape of the end surface is a rectangular parallelepiped shape with rounded corners. The shape of the winding part 20 can be changed as appropriate, and can be, for example, a cylindrical shape, an elliptical cylindrical shape, a racetrack cylindrical shape, or the like. When the winding 2w is directly wound around the cylindrical portion 50 of the bobbin 5A, the shape of the winding portion 20 follows the outer shape (FIGS. 2 and 4) of the cylindrical portion 50. Therefore, when winding directly, it is good to select the shape of the cylindrical part 50 so that the winding part 20 may become a desired shape.

  As the winding 2w constituting the coil 2, a coated wire having an insulating coating on the outer periphery of the conductor wire can be suitably used. As the conductor wire, a round wire made of a conductive material such as copper, aluminum, or an alloy thereof can be suitably used. This is because it can be easily wound around the cylindrical portion 50 of the bobbin 5A. Examples of the constituent material of the insulating coating include resins such as polyamide imide called enamel. A known coil winding can be used as the winding 2w. The winding 2w in this example is a covered round wire.

  In addition, the winding 2w can be a covered rectangular wire, and the winding part 20 can be an edgewise coil. In this case, if the bobbin 5A is a half crack piece or the like that can be divided in the axial direction of the winding part 20, the separately produced edgewise coil can be easily assembled to the bobbin 5A. If the half-cracked piece has an engaging portion or the like and can be integrated, it is possible to suppress the displacement of pedestal parts 52a and 52b (described later) provided on each half-cracked piece, and the rigidity of the bobbin 5A can be reduced. Enhanced.

  The drawing direction of the drawing part of the coil 2 is not particularly limited. The drawer portion in this example is pulled upward as shown in FIG. That is, the lead-out portion is drawn out in a direction perpendicular to the axial direction of the winding portion 20 of the coil 2 and perpendicular to the placement surface 100f of the installation target 100 in the installed state.

-Core-Inner core The inner core 3 is a columnar body mainly composed of a soft magnetic material. Both end surfaces of the inner core 3 are arranged to face two opposing planes of the inner peripheral surface 4 i of the outer core 4, and form a closed magnetic circuit together with the outer core 4. The outer peripheral surface of the inner core 3 is covered with the cylindrical portion 50 of the bobbin 5 </ b> A, and further covered with the winding portion 20 via the cylindrical portion 50. The shape of the inner core 3 can be selected as appropriate. For example, a columnar shape, an elliptical columnar shape, a prismatic shape, etc. are mentioned. As shown in FIG. 4, the inner core 3 in this example is a rectangular parallelepiped member whose end face has a rectangular shape with rounded corners.

..Outer core The outer core 4 is a cylindrical body mainly composed of a soft magnetic material, and, as shown in FIG. 4, from one frame-shaped end surface (upper surface 4u) to the other frame-shaped end surface (lower surface) 4d, FIG. 1, FIG. 5 mentioned later) has an internal space which penetrates, and this internal space is a member formed in a rectangular parallelepiped shape. The outer core 4 has an internal space of the rectangular parallelepiped shape as a storage space for the inner core 3 supported in the cylindrical portion 50 of the bobbin 5A and the winding portion 20 of the coil 2 supported outside the cylindrical portion 50. To do.

  The inner peripheral surface 4i of the outer core 4 includes four rectangular planes arranged in a frame shape. The shape of the outer peripheral surface of the outer core 4 with respect to the inner peripheral surface 4i is not particularly limited as long as a predetermined magnetic path can be formed. That is, the inner peripheral surface 4i and the outer peripheral surface of the outer core 4 can have not only similar shapes but also non-similar shapes. In this example, the inner peripheral surface 4i and the outer peripheral surface of the outer core 4 are similar in shape, that is, the outer peripheral surface is formed in a rectangular parallelepiped rectangular tube surface having four rectangular planes. It is a shaped member. Both end faces 4u and 4d are also flat. When the choke coil 1A is in the installed state, one lower end surface 4d is closed by the placement surface 100f of the installation target 100, and the other upper end surface 4u is opened.

.. Constituent material Both the inner core 3 and the outer core 4 can suitably use a compacted body obtained by compression-molding soft magnetic powder. As the soft magnetic powder, an iron group metal such as iron or an alloy based on an iron group metal element, for example, a metal powder such as an Fe—Si alloy or an Fe—Si—Al alloy can be suitably used. If the soft magnetic powder is a coating powder that has an insulating coating such as phosphate or silicone resin on the surface of the powder particles, the presence of the insulating coating reduces the eddy current loss of the green compact and reduces the loss. Core. In this example, the inner core 3 is a rectangular parallelepiped compacted body with rounded corners, and the outer core 4 is a square cylindrical compacted compact with rounded corners. That is, the choke coil 1A includes two core pieces made of a compacted body.

  In addition, a gap (not shown) may be provided between the inner core 3 and the outer core 4, or the inner core 3 may be an assembly including a plurality of core pieces, and a gap may be provided between adjacent core pieces. it can. In addition to the air gap, a material having a lower magnetic permeability than the core piece, such as a non-magnetic plate material such as alumina, can be used as the gap. In this example, an air gap is provided between the inner core 3 and the outer core 4 by adjusting the thickness of the flanges 51a and 51b (described later) of the bobbin 5A.

  As another constituent material of the core piece, there is a composite material obtained by injection molding or cast molding of a raw material containing soft magnetic powder and resin. The magnetic properties of the inner core 3 (relative magnetic permeability, saturation magnetic flux density, etc.) and the magnetic properties of the outer core 4 can be obtained by combining the green compact and the composite material or by changing the ratio of the magnetic component of the soft magnetic material. You can use different core pieces. In this case, performance such as magnetic characteristics may be improved.

-Bobbin-Overall configuration The bobbin 5A supports the winding part 20 of the coil 2 and is interposed between the inner peripheral surface of the winding part 20 and the outer peripheral surface of the inner core 3 to insulate them from each other. This is one of the functions. The bobbin 5A is interposed between the end surface of the winding part 20 and the inner peripheral surface 4i of the outer core 4 and has one function of insulating the two. For these purposes, the bobbin 5A is made of an electrically insulating material such as resin, which will be described later, and is molded into a predetermined shape.

  The bobbin 5 </ b> A extends from the cylindrical portion 50 interposed between the winding portion 20 of the coil 2 and the inner core 3, and the peripheral edges of both openings of the cylindrical portion 50. A pair of hook-shaped portions 51a and 51b interposed between the core 4 is provided (particularly, FIGS. 2 and 4).

  The bobbin 5A provided to the choke coil 1A functions to support the outer core 4 and to determine the distance D (FIG. 3) between the winding part 20 of the coil 2 supported by the cylindrical part 50 and the installation target 100. One of them. For this purpose, the bobbin 5A is mounted on the installation side end surface (lower end surface 4d) facing the mounting surface 100f of the installation target 100 in the outer core 4 and extending from the periphery of each of the bowl-shaped portions 51a and 51b. Pedestal portions 52a and 52b interposed between the surface 100f are provided.

  Further, the bobbin 5A of this example includes fixing portions 53a and 53b for fixing the choke coil 1A to the installation target 100, and a wall portion 54a (54b) that sandwiches the outer core 4 with the flange-shaped portion 51a (51b). Also equipped. The bobbin 5A has a cylindrical portion 50 as a center, a flange-shaped portion 51a, a pedestal portion 52a, a fixing portion 53a, and a wall portion 54a on one end side in the axial direction, and a flange-shaped portion on the other end side in the axial direction. This is an integrally molded product including 51b, a pedestal portion 52b, a fixing portion 53b, and a wall portion 54b. Hereinafter, each element of the bobbin 5A will be described.

..Cylindrical part The cylindrical part 50 uses the internal space as a storage space for the inner core 3, and the outer peripheral surface of the cylindrical part 50 as the arrangement region of the winding part 20 of the coil 2 (FIG. 4). The cylindrical part 50 of this example supports the winding part 20 so that the outermost peripheral surface of the winding part 20 slightly protrudes from the installation side end face (lower end face 4d) of the outer core 4 (FIG. 3). The cylindrical portion 50 in this example is a cylindrical body having a rectangular parallelepiped shape with rounded corners, and the shape can be appropriately selected as described in the section of the coil. The inner core 3 inserted into the cylindrical portion 50 can be fixed using an adhesive or the like.

.. Wedge-shaped portion Both of the hook-shaped portions 51a and 51b in this example are rectangular shapes having a size corresponding to the opposing rectangular plane of the inner peripheral surface 4i of the outer core 4 as shown in FIG. As shown in FIGS. 2 and 4, an opening portion of the cylindrical portion 50 is provided at the center portion. Each of the hook-shaped parts 51a and 51b has an outer shape sufficiently larger than the contour formed by the end face of the winding part 20 of the coil 2, and can sufficiently cover the end face of the winding part 20 (particularly, FIG. 4). In addition, the hook-shaped portions 51 a and 51 b can have the same shape and size as the end surface shape of the winding portion 20. However, even in this case, a connection region with the pedestal portions 52a and 52b is provided.

  In this example, among the four sides of the rectangular bowl-shaped portions 51a and 51b, one side on the installation object 100 side is the connection edge of the pedestal portions 52a and 52b, and the other three sides are rounded. (Refer to the peripheral edges of the three sides of the hook-shaped part 51a in FIG. 2), flattening (see the upper peripheral edge of the hook-shaped part 51b in FIG. 4), or a stepped shape (the hook-shaped part 51b in FIG. 4). See the left and right edges of When the peripheral edges of the hook-shaped portions 51a and 51b have such an irregular shape, the creepage distance from the end surface of the coil 2 to the inner peripheral surface 4i of the outer core 4 is increased as compared with a case where the orthogonal planes are combined. It is possible to prevent creeping discharge during this period and to have excellent insulation. In addition, the inner side surface which contacts the winding part 20 of the coil 2 among the hook-shaped parts 51 a and 51 b can be provided with a spiral recess along the end surface of the winding part 20.

.. Pedestal portion The pedestal portions 52a and 52b are interposed between the outer core 4 and the installation target 100 and support the outer core 4 separately from the mounting surface 100f. The pedestal portions 52a and 52b in this example are rectangular flat plates that extend along the axial direction of the cylindrical portion 50 (the lower diagram in FIG. 1). In other words, the bowl-shaped part 51a (51b) and the pedestal part 52a (52b) are connected in an L shape (FIG. 3). One surface of the pedestal portions 52a and 52b is an installation surface 52d supported by the mounting surface 100f of the installation object 100 (lower view in FIG. 1, FIG. 3), and the other surface facing the installation surface end surface of the outer core 4 ( This is a support surface 52u that supports the lower end surface 4d) (FIGS. 2 and 3). In this example, since both surfaces 52u and 52d are flat, the bobbin 5A is stably supported by the installation object 100 and the outer core 4 is stably supported by the bobbin 5.

  Here, in the pedestal parts 52a and 52b, the size along the axial direction of the cylindrical part 50 is defined as the length, and the direction perpendicular to the length direction (here, along the longitudinal direction of the connecting edges of the bowl-shaped parts 51a and 51b). The direction) is the width. The length of the pedestal portions 52a and 52b in this example is equal to or greater than the thickness of the installation side end surface (lower end surface 4d) of the outer core 4 (FIG. 3). The widths of the pedestal portions 52a and 52b are substantially the same as the widths of the bowl-shaped portions 51a and 51b (see the broken line in FIG. 2 for the pedestal portion 52a and the broken line in FIG. 4 for the pedestal portion 52b).

The shape and size (length, width) of the pedestal portions 52a and 52b can be changed as appropriate.
1. For example, the pedestal portion can be a flat plate having an arbitrary shape other than a rectangle.
2. For example, the length of the pedestal portion can be made smaller than the thickness of the installation side end surface (lower end surface 4d) of the outer core 4.
3. For example, the width of the pedestal portion can be made shorter or longer than the width of the bowl-shaped portions 51a and 51b.
4). For example, a plurality of pedestal portions having a short width can be separated and arranged in parallel, instead of using a single flat plate as a pedestal portion extending in one bowl-shaped portion.
5. For example, the support surface 52u of the bobbin 5A is not a uniform plane, but can be provided with a recess (not shown) to form an uneven shape, and the recess can be filled with a fixing material for the outer core 4. In this case, the outer core 4 and the bobbin 5A can be firmly fixed. As the fixing material, a constituent material of the resin portion 7 of Embodiment 3 to be described later can be used.

  The thickness of the pedestal portions 52a and 52b is one of the elements that determine the distance D (FIG. 3) between the winding portion 20 of the coil 2 and the installation target 100. The thickness of the pedestal portions 52a and 52b is the sum of the protruding height of the portion protruding from the installation side end surface (lower end surface 4d) of the outer core 4 in the winding portion 20 and the thickness of the heat radiation layer 6A. If the thickness of the pedestal portions 52a and 52b is too thick, it is necessary to increase the heat dissipation layer 6A, which leads to an increase in the size of the choke coil 1A, and if it is too thin, the insulation distance between the winding portion 20 and the installation target 100 is not good. Can be enough. Here, when the heat dissipation layer 6A uses an elastically deformable material that can be compressed to some extent, the distance D can be adjusted to some extent by the thickness of the heat dissipation layer 6A and the amount of compression. Therefore, the thickness of the pedestal portions 52a and 52b may be selected according to the thickness of the heat radiation layer 6A, the amount of compression, and the like within a range that is not too thick or too thin as described above. As for the thickness of the base parts 52a and 52b, about 1 mm or more and about 3 mm or less are mentioned, for example. When the protruding portion of the winding part 20 is embedded in the heat dissipation layer 6A, the thickness of the pedestals 52a and 52b is substantially the thickness of the heat dissipation layer 6A, and FIG. 3 shows this state. .

.. Fixing part The fixing parts 53a and 53b are extended to the pedestal parts 52a and 52b, respectively. The fixing portions 53a and 53b in this example are projecting pieces that protrude from the center portion in the width direction at the edge portions of the pedestal portions 52a and 52b, and have a rectangular flat plate shape (FIG. 1). One through hole 5h is provided at the center of the projecting piece through which a fastening member such as a bolt or a screw for fixing the choke coil 1A to the installation target 100 is inserted. The through-hole 5h can be integrally formed with a resin or the like that constitutes the fixing portions 53a and 53b. In this example, the through-hole 5h is formed of a metal cylinder. This is because if the end surface of the metal cylinder is used as a pressure receiving surface for the fastening force of the fastening member, the metal is superior in strength to resin and the like, so that it is difficult to crack at the time of fastening, and a decrease in the fastening force over time can be suppressed. The metal cylinder can be easily integrated with the resin or the like constituting the fixing portions 53a and 53b by insert molding or the like.

  The number, shape, formation position, and the like of the fixing portions 53a and 53b can be changed as appropriate. For example, a fixing part can be provided on each end in the length direction of the pedestal parts 52a and 52b. That is, it is possible to provide two fixing parts with respect to one pedestal part, and further provide further fixing parts. When there are many fixing portions (for example, a total of four), it is possible to increase the fixing strength with respect to the installation target 100 or to prevent positional deviation. When the number of fixing portions is small (for example, two as in this example), the tightening process is small and the installation workability is excellent.

..Wall portion The wall portions 54a and 54b are respectively erected from the support surfaces 52u and 52u of the pedestal portions 52a and 52b, and are arranged to face the flange portions 51a and 51b (FIG. 3). The outer core 4 is fitted between the flanged portion 51a and the wall portion 54a, and between the flanged portion 51b and the wall portion 54b, respectively, so that the outer core 4 is positioned and sandwiched. For this purpose, the distance between the flange 51a and the wall 54a and the distance between the flange 51b and the wall 54b are substantially equal to the thickness of the outer core 4.

  Each of the wall portions 54a and 54b in this example is a flat plate provided over the entire width of the pedestal portions 52a and 52b and arranged in parallel with the bowl-shaped portions 51a and 51b. In particular, in this example, the wall portion 54a erected on one pedestal portion 52a is a rectangular flat plate, and the erected height is higher than the lower edge of the tubular portion 50 in the bowl-shaped portion 51a. (FIGS. 2 and 3). Therefore, a part of one opening part of the cylindrical part 50 is covered with the wall part 54a (FIG. 1, FIG. 2). The wall portion 54b erected on the other pedestal portion 52b is a U-shaped flat plate, in other words, a flat plate in which a central portion in the width direction of a rectangular flat plate is cut out (FIG. 4). The wall portion 54 b includes a notch (shaft notch 540) that forms an edge corresponding to the opening edge of the tubular portion 50. The wall portion 54b having the shaft notch 540 has a maximum standing height higher than the lower edge of the tubular portion 50 in the bowl-shaped portion 51b, and the minimum standing height is the same as the lower edge of the tubular portion 50. It is about. Therefore, a winding shaft (not shown) of a winding machine that winds the inner core 3 and the winding 2 w can be easily inserted into the cylindrical portion 50 through the shaft notch 540. And the outer core 4 can be clamped favorably by sufficiently increasing the (maximum) standing height of the walls 54a and 54b.

  As for wall part 54a, 54b of this example, as for all, the thickness of the edge part side area | region and the thickness of the connection side area | region with the base parts 52a and 52b differ. Specifically, the edge side regions of the walls 54a and 54b are each provided with introduction portions 542 and 542 that are inclined so that the thickness increases from the edge toward the connection side with the pedestals 52a and 52b ( FIG. 3). By providing the introduction portion 542, the interval between the flange portion 51a and the wall portion 54a and the interval between the flange portion 51b and the wall portion 54b are set in the height direction of the wall portion (the vertical direction in FIG. It is not uniform in the direction orthogonal to the winding part 20, but extends toward the edge side, and is wider than the thickness of the outer core 4 (FIG. 3). Therefore, while the outer core 4 can be easily inserted by the introduction part 542, the outer core 4 can be positioned and held by the connection side region having a narrow interval.

The number, shape, formation position, size (length, standing height, thickness, etc.) of the wall portions 54a and 54b can be appropriately changed. For example, the following changes can be mentioned.
1. For example, one of the walls 54a and 54b can be omitted. In this case, the distance between the one wall portion and the hook-shaped portion parallel to the wall portion is substantially equal to the thickness of the outer core 4, so that the outer core 4 can be positioned with high accuracy and can be held. It can be done firmly.
2. For example, the width of at least one of the wall portions 54a and 54b can be made shorter than the width of the pedestal portions 52a and 52b. In this case, the outer core 4 can be firmly held when the plurality of wall portions are separated and provided in parallel.
3. For example, the height of at least one of the wall portions 54a and 54b can be made lower than the lower edge of the tubular portion 50 in the flange portions 51a and 51b. In this case, when inserting the inner core 3 or the winding shaft of the above-described winding machine into the cylindrical portion 50, the inner core 3 or the winding shaft does not interfere with the wall portion, and the insertability of the inner core 3 or the winding shaft is improved. While being excellent, the outer core 4 can be positioned and held between the wall portion and the bowl-shaped portion.
4). For example, the interval between the wall portion and the bowl-shaped portion can be made sufficiently wider than the thickness of the outer core 4. In this case, the insertability of the outer core 4 is excellent. A resin portion 7 described in a third embodiment to be described later can be provided in a gap generated between the wall portion, the bowl-shaped portion, and the outer core 4.
5. For example, at least one wall portion of the wall portions 54a and 54b does not include the introduction portion 542, and can have a uniform thickness. In this case, for example, the thickness of the wall portion not provided with the introduction portion 542 is reduced to have a certain degree of elasticity, and the edge portion side of the wall portion is warped when the outer core 4 is inserted, so that the hook-shaped portion and the wall Increasing the distance from the part makes it easier to insert the outer core 4. The warped wall can be returned by its own elasticity.

.. Constituent material As the constituent material of the bobbin 5A, a resin excellent in electrical insulation can be suitably used. For example, polybutylene terephthalate (PBT) resin, polyphenylene sulfide (PPS) resin, polytetrafluoroethylene (PTFE) resin, liquid crystal polymer (LCP), polyamide (PA) resin such as nylon 6 and nylon 66, acrylonitrile butadiene styrene ( (ABS) and other thermoplastic resins. If it is a thermoplastic resin, the bobbin 5A having a complicated three-dimensional shape as described above can be easily and accurately molded by using injection molding or the like.

  Examples of other constituent materials include thermosetting resins such as unsaturated polyester resins, epoxy resins, urethane resins, and silicone resins.

  When a ceramic filler is contained in the resin, the thermal conductivity and electrical insulation of the bobbin 5A can be improved. Examples of the ceramic filler include nonmagnetic powders such as alumina and silica.

Heat dissipation layer The heat dissipation layer 6 </ b> A contacts the installation side region facing the installation target 100 in the winding part 20 of the coil 2, and transmits heat generated by energization of the coil 2 (winding part 20) to the installation target 100. Functions as a heat dissipation path. The heat radiating layer 6A of this example uses a heat radiating sheet having a length substantially the same as the axial length of the winding portion 20, and in a state where the heat radiating layer 6A is attached to the winding portion 20, FIG. As shown in the following figure and FIG. 3, it is pinched | interposed between a pair of base parts 52a and 52b. Further, the heat radiating sheet has a width that allows sufficient contact with the installation side region of the winding portion 20 as described above, and can be stored in an opening space formed by the installation side end surface (lower cross section 4d) of the outer core 4. It is a large size (lower figure in FIG. 1).

  The heat dissipation layer 6A is made of a material having excellent thermal conductivity. The heat conductivity of the heat radiation layer 6A is preferably as high as possible, and is preferably 1 W / m · K or more, more preferably 2 W / m · K or more, and 3 W / m · K or more. Examples of the constituent material of the heat dissipation layer 6A include resins such as silicone resin and acrylic resin. When constituted by the resin containing the ceramic filler described above, the heat dissipation layer 6A is more excellent in thermal conductivity.

  6 A of heat radiating layers can utilize suitably the heat radiating sheet which has the above high heat conductivity. This is because the heat-dissipating sheet does not require an application process or a solidification process, and can be easily prepared in a desired shape and size by cutting, and is easy to handle. A well-known heat dissipation sheet can be used. In addition to the heat dissipation sheet, a coating layer such as a resin that satisfies the thermal conductivity can be used.

  The heat-dissipating sheet preferably has elastic deformability that can be compressed to some extent. The heat-dissipating sheet and the winding part 20 of the coil 2 are brought into contact, the winding part 20 is pressed to deform one surface of the heat-dissipating sheet along the shape of each turn, and the contact area of the winding part 20 with each turn It is because heat dissipation can be improved more by increasing. By pressing the winding portion 20 against the heat radiating sheet, a part of each turn (particularly the region protruding from the lower end surface 4d of the outer core 4) is embedded in the heat radiating sheet. As such a heat radiating sheet, for example, one having an Asker C hardness of 40 or less before compression can be mentioned. In addition, in the heat-radiation sheet after compression, the hardness of a compression location may become higher than the hardness before compression. If the Asker C hardness before compression is 40 or less, the Asker C hardness at the compression portion is about 80 or less even if the hardness increases after compression.

  Moreover, what has adhesiveness to some extent is preferable for a thermal radiation sheet. It is because the winding part 20 and a heat radiating sheet can be closely_contact | adhered by pressing the winding part 20 as mentioned above, and heat dissipation is improved. When performing such compression, the thickness of the heat radiation sheet is preferably thicker than the design value of the distance D between the winding part 20 and the installation target 100 in consideration of the amount of compression.

  The length, width, thickness, and the like of the heat dissipation layer 6A can be changed as appropriate. As shown in this example, when the heat dissipation layer 6A is formed by a heat dissipation sheet having a plane area smaller than the opening area of the installation side end surface (lower end surface 4d) of the outer core 4, the heat dissipation layer 6A can be accommodated in the outer core 4, The choke coil 1 </ b> A can be stably installed on the installation target 100. As will be described later in Embodiment 2, a heat radiation sheet having a length that cannot be stored in the outer core 4 can be used.

.. Others When the choke coil 1A is transported to the installation target 100, if a flat tray (not shown) or the like is used to transport the choke coil 1A while it is placed on the tray, the heat radiation layer 6A is dropped, etc. Can be prevented. If a release material such as release paper is provided in the arrangement area of the heat dissipation layer 6A in the tray, the heat dissipation sheet and the tray can be easily separated even when an adhesive heat dissipation sheet is used as the heat dissipation layer 6A. A typical example of the tray is a resin plate, but it is possible to use a metal plate that is excellent in heat dissipation such as aluminum or an alloy thereof and is light in weight and used as a heat dissipation member. In this case, a metal plate is attached to the installation object 100 together with the choke coil 1A. If the metal plate is provided with a through-hole through which a bolt or the like is inserted at a position corresponding to the through-hole 5h, 5h of the fixing portion 53a, 53b, the choke coil 1A and a metal plate serving as a heat dissipation member are installed. It can be fixed to the target at the same time and has excellent installation workability.

-Choke coil manufacturing method The choke coil 1A of Embodiment 1 can be manufactured as follows, for example.
(Α) The bobbin 5 </ b> A is manufactured, and the winding portion 2 is formed by winding the winding 2 w around the cylindrical portion 50.
(Β) The inner core 3 is housed in the cylindrical portion 50.
(Γ) With respect to the bobbin 5A that holds the inner core 3 and the coil 2 inside and outside the cylindrical portion 50, the outer portion is between the flange portion 51a and the wall portion 54a and between the flange portion 51b and the wall portion 54b. The core 4 is fitted, and the installation side end face (lower end face 4d) of the outer core 4 is supported by the pedestals 52a and 52b.
(Δ) The heat dissipation layer 6A and the winding part 20 are brought into contact with each other.

-Installation of choke coil The choke coil 1A is placed on the placement surface 100f of the installation object 100, and a fastening member such as a bolt is inserted into and tightened into the through holes 5h, 5h of the fixing portions 53a, 53b. 1A can be fixed to the installation object 100.

Effect When the choke coil 1A of the first embodiment is placed on the installation target 100, the base portions 52a and 52b of the bobbin 5A are interposed between the installation side end surface (lower end surface 4d) of the outer core 4 and the placement surface 100f. Thus, the winding part 20 of the coil 2 supported by the cylindrical part 50 integrated with the pedestal parts 52a and 52b is supported by being separated from the placement surface 100f by the bobbin 5A. The distance D between the winding part 20 and the mounting surface 100f is automatically determined by the pedestal parts 52a and 52b that are part of the bobbin 5A. That is, in the choke coil 1A, the distance D is determined by the pedestal portions 52a and 52b with a very small molding error. Therefore, even if the outer core 4 is a green compact and the molding error becomes large and the height H ₄ (FIG. 3) varies, the choke coil 1A has the size of the outer core 4 (particularly the height H). ₄ ) The distance D is not easily affected or substantially not affected, and the distance D is stable. Since the distance D stably has a certain size, the choke coil 1A need not use a thick heat dissipation sheet for the heat dissipation layer 6A, and can use a thin heat dissipation sheet.

In addition, the choke coil 1A of this example has the following effects.
-By providing the fixing portions 53a and 53b, a fixture such as a leaf spring is unnecessary, the number of parts is small, and the installation workability to the installation target 100 is excellent.
-By providing wall part 54a, 54b, the outer core 4 can be positioned easily, it is excellent in assembly workability | operativity, and the outer core 4 can be hold | maintained.
-By providing the notch 540 for shafts in one wall part 54b, the inner core 3 and a winding shaft can be easily penetrated in the cylindrical part 50, and it is excellent in assembly workability and winding workability.
-By providing the introduction portions 542 and 542 in the wall portions 54a and 54b, the outer core 4 can be easily inserted between the flange portion 51a and the wall portion 54a, and between the flange portion 51b and the wall portion 54b, Excellent assembly workability.

[Embodiment 2]
Hereinafter, the choke coil 1 </ b> B according to the second embodiment will be described with reference to FIGS. 5 and 6. The choke coil 1B has a point that the heat radiation layer 6B is longer than the choke coil 1A of the first embodiment, and the pedestal portions 52a and 52b of the bobbin 5B are formed so as not to interfere with the heat radiation layer 6B. Is the main difference. Hereinafter, this difference will be described in detail, and detailed description of other configurations and effects will be omitted. FIG. 5 shows a state in which the choke coil 1B is viewed from the installation surface side, and shows a state in which the heat radiation layer 6B (heat radiation sheet) is removed so that the pedestals 52a and 52b can be easily understood. FIG. 6 shows a state in which the outer core 4, the bobbin 5 </ b> B, and the heat dissipation layer 6 </ b> B are cut out of the choke coil 1 </ b> B in a cross section parallel to the axial direction of the coil 2.

-Heat dissipation layer In the choke coil 1A of the first embodiment described above, the length of the heat dissipation layer 6A is substantially equal to the axial length of the winding portion 20 of the coil 2 (Fig. 3). In the choke coil 1B of the second embodiment, as shown in FIG. 6, the length of the heat radiation layer 6B is sufficiently longer than the axial length of the winding part 20 of the coil 2, and both ends are on the installation side end face (lower side) of the outer core 4. It extends to the end face 4d). That is, the heat dissipation layer 6B includes a base 60 that covers the installation side region of the winding portion 20, and extension regions 62 and 62 that are disposed across the end surface of the winding portion 20 and the inner peripheral surface 4i of the outer core 4. Have In this example, the length of the extension region 62 is adjusted so that the entire area of the installation side end face (lower end face 4d) of the outer core 4 is covered with the heat dissipation layer 6B. Such a heat dissipation layer 6B is the above-described heat dissipation sheet, and a long one can be used.

-Bobbin If the long heat dissipation layer 6B as described above is disposed on the bobbin 5A described in the first embodiment as it is, the extension region 62 of the heat dissipation layer 6B and the pedestals 52a and 52b interfere with each other. Therefore, the pedestal portions 52a and 52b in this example have a gate shape as shown in FIG. 5 and have openings. Specifically, the pedestal portions 52a and 52b of the bobbin 5B include a heat radiation notch 520 into which the extension region 62 of the heat radiation layer 6B is fitted. As shown in FIG. 5, in a state where the heat radiation layer 6B is removed, a part of the installation side end surface (lower end surface 4d) of the outer core 4 is exposed from the opening formed by the heat radiation notch 520.

  The size (opening area), shape, and the like of the heat radiation notch 520 may be adjusted according to the size, shape, and the like of the heat radiation sheet used for the heat radiation layer 6B. In this example, since a rectangular heat radiation sheet is used as shown in FIG. 5, the heat radiation notch 520 has a rectangular opening shape, and its size (opening area) is substantially equal to the size of both ends of the heat radiation sheet. Is equal to The larger the size of the heat radiation notch 520, the larger the heat radiation sheet can be arranged, the contact area between the outer core 4 and the heat radiation layer 6B can be increased, and the smaller the size, the higher the rigidity of the bobbin 5B.

  In addition, a pedestal portion can be provided at a position where the heat dissipation layer 6B is not disposed so as not to interfere with the heat dissipation layer 6B. For example, a region near the both side edges of the bowl-shaped portions 51a and 51b can be used as a connection region with the pedestal portion, and a pedestal portion with a narrow width can be provided. In this case, for example, two pedestal portions can be provided in one bowl-shaped portion, and a fixing portion can be provided on the extension.

Effect The choke coil 1B according to the second embodiment has the effect of the choke coil 1A according to the first embodiment and includes the long heat dissipation layer 6B, so that not only the winding portion 20 of the coil 2 but also the outer core 4 is provided. It can contact the heat dissipation layer 6B. Therefore, the choke coil 1 </ b> B can transmit heat from the outer core 4 to the installation target 100 and is more excellent in heat dissipation.

[Embodiment 3]
Hereinafter, the choke coil 1C of the third embodiment will be described with reference to FIG. This choke coil 1C is different from the first embodiment in that the choke coil 1C includes resin portions 7 and 7 between the flange portion 51a and the wall portion 54a, and between the flange portion 51b and the wall portion 54b. It is. Hereinafter, this difference will be described in detail, and detailed description of other configurations and effects will be omitted. 7 and FIG. 8 to be described later show a state in which the outer core 4 is cut along a cross section parallel to the axial direction of the coil 2 as in FIG. FIG. 7 shows a state in which the resin portion 7 and FIG.

-Resin part The resin part 7 is a member which fixes the outer core 4 and the bobbin 5C which are each interposed between the collar part 51a and the wall part 54a, and between the collar part 51b and the wall part 54b. For this purpose, an appropriate material capable of fixing the outer core 4 and the bobbin 5b can be used as the constituent material of the resin portion 7. In particular, it is preferable that the resin portion 7 includes an adhesive because it can be firmly fixed. Specific constituent materials of the resin part 7 include epoxy resin, silicone resin, acrylic resin, and the like.

  As long as the outer core 4 can be fixed between the flange portion 51a and the wall portion 54a and between the flange portion 51b and the wall portion 54b, the resin portion 7 can be appropriately selected in its formation position and size. In FIG. 7, the resin portion 7 is provided between the outer core 4 and the wall portion 54a so that the outer core 4 is moved toward the flange-shaped portion 51a, and the outer core 4 is moved toward the flange-shaped portion 51b. The resin part 7 is provided between the outer core 4 and the wall part 54b. In this case, it is easy to bring the inner core 3 and the outer core 4 into close contact with each other and to maintain a predetermined gap distance between the both cores 3 and 4. In addition, the outer core 4 is moved to the wall portion 54a (54b), and the resin portion 7 is provided between the flange-shaped portion 51a (54b) and the outer core 4, or between the flange-shaped portion 51a and the wall portion 54a and The resin part 7 can be provided only in either one between the hook-shaped part 51b and the wall part 54b.

The bobbin 5C provided to the bobbin choke coil 1C may be the same as the bobbin 5A provided to the choke coil 1A of the first embodiment, but in this example, the interval between the hook-shaped part 51a and the wall part 54a, the hook-shaped part 51b and the wall part The distance from 54b is slightly wider than the bobbin 5A of the first embodiment. By doing so, it is easy to insert the outer core 4 between the hook-shaped part 51a and the wall part 54a and between the hook-shaped part 51b and the wall part 54b, and the assembly workability is excellent. By widening the gap, a gap is provided between the flange 51a, the outer core 4, and the wall 54a, and between the flange 51b, the outer core 4, and the wall 54b. This gap is filled with the resin portion 7.

Effect The choke coil 1C according to the third embodiment can firmly fix the outer core 4 and the bobbin 5C by providing the resin portion 7 in addition to the effects of the choke coil 1A according to the first embodiment. Further, since the outer core 4 and the bobbin 5C are integrated by the resin portion 7, the coil 2, the inner core 3 (FIG. 1), the outer core 4 and the bobbin 5C can be handled as an integrated assembly, and the transfer work Excellent in workability and installation workability.

[Embodiment 4]
Hereinafter, the choke coil 1D of the fourth embodiment will be described with reference to FIG. This choke coil 1D is different from the first embodiment in that, in addition to the choke coil 1A of the first embodiment, an insulating layer 8 is provided between the heat radiation layer 6A and the installation target 100. Hereinafter, this difference will be described in detail, and detailed description of other configurations and effects will be omitted.

-Insulating layer The insulating layer 8 is a member for improving the electrical insulation between the winding part 20 of the coil 2 and the installation object 100. For this purpose, the insulating layer 8 is made of a material having excellent electrical insulation. As an index of electrical insulation, it may be mentioned that the dielectric breakdown voltage is about 2.5 kV / 50 μm or more.

  The insulating layer 8 preferably has a size and shape that can be disposed across the end face of the winding part 20 of the coil 2 and the inner peripheral face 4 i of the outer core 4. Here, when the heat dissipation layer 6 </ b> A is made of an insulating material, the insulating layer 6 </ b> A can be regarded as an insulating material between the winding part 20 and the installation target 100. However, when the length of the heat dissipation layer 6A is substantially equal to the axial length of the winding part 20, creeping discharge may occur from the end face of the winding part 20 to the installation target 100. The insulating layer 8 is interposed between the heat radiation layer 6 </ b> A and the installation target 100 so as to straddle the end surface of the winding unit 20 and the inner peripheral surface 4 i of the outer core 4, so that the installation target 100 from the end surface of the winding unit 20. It is possible to effectively prevent creeping discharge by increasing the creeping distance to.

  The size and shape of the insulating layer 8 can be selected as appropriate. In this example, a part of the installation side end surface (lower end surface 4d) of the outer core 4 (a region exposed without being covered by the base parts 52a and 52b of the bobbin 5A), the base parts 52a and 52b of the bobbin 5A, A rectangular insulating sheet having an area that can cover the heat dissipation layer 6 </ b> A is used for the insulating layer 8. In this case: 1. Simple shape and easy to manufacture. 2. Easy to place on the installation object 100; It is possible to obtain various effects such as excellent installation workability without positioning the mounted object with respect to the insulating layer 8 with high accuracy. In addition, a rectangular frame-like insulating sheet can be used.

  The thinner the insulating layer 8 is, the smaller the bulk and the smaller the choke coil 1D is. The thicker the insulating layer 8, the higher the electrical insulation. For example, the thickness of the insulating layer 8 is 0.1 mm or more and 0.5 mm or less, more preferably 0.2 mm or more and 0.4 mm or less, and 0.25 mm or more and 0.35 mm or less.

  Examples of the constituent material of the insulating layer 8 include a silicone resin and a polyimide resin. When the insulating layer 8 is made of a resin containing the ceramic filler described above, the insulating layer 8 is excellent in electrical insulation and heat dissipation. When such an insulating sheet made of resin is used for the insulating layer 8, the bobbin has an adhesive layer on at least one surface, preferably both surfaces of the insulating sheet, or the sheet itself has adhesiveness. It is preferable because it can be in close contact with 5A and the heat dissipation layer 6A.

Effect The choke coil 1D of the fourth embodiment includes the insulating layer 8 in addition to the effects of the choke coil 1A of the first embodiment, and therefore has a sufficiently long creepage distance from the winding part 20 to the installation target 100. It can be secured. Therefore, the choke coil 1 </ b> D is superior in electrical insulation between the winding part 20 and the installation target 100.

[Modification 1]
Embodiment 1 etc. demonstrated the form provided with fixing | fixed part 53a, 53b and wall part 54a, 54b. Of these, at least one of them can be omitted.

[Modification 2]
In the first embodiment and the like, the form in which the inner core 3 and the bobbin 5A are independent members has been described. In addition, the inner core 3 can be integrally formed with the cylindrical portion 50 by using insert molding or the like for manufacturing the bobbin 5A. In this case, the number of assembly parts can be reduced.

[Modification 3]
In Embodiment 1 etc., the form which the cylindrical part 50 of 5 A of bobbins penetrated was demonstrated. In addition, it can be set as the form which seals one opening part of the cylindrical part 50. FIG. For example, it is possible to use a flat plate material in which the hook-like portion 51b parallel to the wall portion 54b having the shaft notch 542 is opened and the hook-like portion 51a parallel to the flat wall portion 54a is closed. In this case, the sealed hook-shaped part 51a can be used for holding the inner core 3, and the position of the inner core 3 in the cylindrical part 50 can be determined with high accuracy. In this case, the sealing portion can be used as a gap interposed between the inner core 3 and the outer core 4.

  The present invention is not limited to these exemplifications, but is defined by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

  The choke coil of the present invention can be used for various circuit components that perform boosting, power factor correction, current smoothing, and the like of a power supply circuit. Examples of a device including such a circuit include a power conversion device such as a bidirectional DC-DC converter mounted on a vehicle such as a hybrid vehicle, an electric vehicle, and a fuel cell vehicle.

1A, 1B, 1C, 1D Choke coil 2 Coil 20 Winding part 2w Winding 3 Inner core 4 Outer core 4d Lower end face (Installation side end face) 4u Upper end face 4i Inner peripheral face 5A, 5B, 5C Bobbin 50 Cylindrical part 51a , 51b Hook-shaped portion 52a, 52b Base portion 52u Support surface 52d Installation surface 520 Radiation notch 53a, 53b Fixing portion 5h Through hole 54a, 54b Wall portion 540 Shaft notch 542 Introduction portion 6A, 6B Heat radiation layer 60 Base 62 Extension region 7 Resin part 8 Insulating layer 100 Installation object 100f Mounting surface

Claims (8)

A coil having a winding portion formed by winding a winding;
A columnar inner core housed in the winding section;
A bobbin having a cylindrical portion interposed between the wound portion and the inner core;
A cylindrical outer core that has a rectangular parallelepiped internal space that accommodates the inner core and the winding portion supported inside and outside the cylindrical portion, and forms a closed magnetic path together with the inner core;
A heat dissipation layer interposed between the winding part and the installation target,
The bobbin is
A pair of hook-shaped portions extending from the peripheral edges of both openings of the cylindrical portion and interposed between the end surface of the winding portion and the inner peripheral surface of the outer core;
A pedestal portion that extends between the periphery of each bowl-shaped portion along the axial direction of the cylindrical portion and that is interposed between the installation-side end surface of the outer core that faces the installation target and the installation target. Provided choke coil.   The choke coil according to claim 1, wherein the bobbin includes a fixing portion that extends from the pedestal portion and fixes the choke coil to the installation target.   3. The choke coil according to claim 1, wherein the heat dissipation layer has an extended region that is disposed across an end surface of the winding portion and an inner peripheral surface of the outer core.   The said bobbin is standing from the said base part, is arrange | positioned facing the said hook-shaped part, and is provided with the wall part which pinches | interposes the said outer core between the said hook-shaped parts. The choke coil described in 1.   The choke coil according to claim 4, wherein the wall portion includes a notch that forms an edge portion corresponding to an opening edge of the cylindrical portion.   The choke coil according to claim 4 or 5, wherein the wall portion includes an introduction portion that is inclined so that a thickness thereof increases from an edge portion of the wall portion toward the pedestal portion side.   The choke coil according to any one of claims 4 to 6, further comprising a resin portion that fixes the outer core interposed between the flange-shaped portion and the wall portion.   Any one of Claims 1-7 provided with the insulating layer which is interposed between the said thermal radiation layer and the said installation object, and is arrange | positioned ranging over the end surface of the said winding part, and the internal peripheral surface of the said outer core. The choke coil according to item.

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