JP6527361B2 - Inductor - Google Patents

Description

  The present invention relates to an inductor having a toroidal core.

  Inductors such as coils always generate heat. The inductor is generally fixed to a substrate or the like (hereinafter referred to as a "mounted body") of various devices using the same, but as the amount of current flowing through the winding and the frequency increase, the inductor is generally used. Since the amount of heat dissipated to the surroundings also increases, it is necessary to take some measures against heat in order to avoid the influence of heat generation on the mounting object.

  Here, the invention of a coil component having a structure in which an opening at one end of a coil cover for accommodating a coil assembly in which a winding is applied to a toroidal core is closed by a heat sink plate is already known (see, for example, Patent Document 1). According to this coil component, since the heat sink plate is disposed facing the annular end face of the coil assembly and the toroidal core, the heat generated from the coil assembly can be dissipated to the heat sink plate.

JP 2007-234752 A

  Normally, since the toroidal core is of a shape of which the inner peripheral side is naturally narrower than the outer peripheral side (circumferential length is shorter), the inner side can be aligned with a margin on the outer peripheral side as the number of windings increases. On the circumferential side, the windings overlap with each other, making it difficult to align. And since the overlapping portion and the non-overlapping portion of the windings are sparse, the winding arrangement, which should be called the end face of the coil assembly in which the winding has been finished, is not even finished (flat in terms of surface) Irregularities occur on the Due to the unevenness, even if the coil assembly is disposed to face the heat sink plate, it is difficult to efficiently dissipate the heat from the opposite end face to the heat sink plate.

  Then, this invention makes it a subject to provide the inductor which can improve heat dissipation.

In order to solve the above-mentioned subject, the present invention adopts the following solution means.
That is, the inductor according to the present invention includes the core formed in an annular shape, and the resin member covering at least a part of the surface of the core, and the resin member is paired in the axial direction of the annular portion around which the winding is wound. The heat dissipation surface is disposed opposite to the heat dissipation member as one of the two end surfaces formed, and the unevenness suppressing structure is provided to suppress the unevenness caused by the overlapping of the windings on the heat dissipation surface. .

  By adopting such a configuration, the arrangement of the windings on the heat dissipation surface can be aligned and brought closer to being flatter. Therefore, when the inductor as a finished product is mounted on the mounting body, it can face substantially parallel to the heat dissipation member disposed between the mounting body and the mounting body, and the heat dissipation surface is a wider area. Since it is possible to contact the member, it is possible to efficiently transmit the heat released from the heat dissipation surface to the heat dissipation member to improve the heat dissipation performance.

  The plurality of unevenness suppressing structures are formed at least at the corner portions connected to the heat radiation surface among the corner portions on the inner peripheral side connected between the inner peripheral surface and the end surface of the annular portions adjacent to each other to promote alignment of the windings. Containing grooves. Preferably, in addition to the inner corner portion, at least the corner portion connected to the heat dissipation surface among the corner portions on the outer peripheral side connected between the outer peripheral surface and the end face of the annular portions adjacent to each other It further includes a plurality of grooves to facilitate alignment of the windings.

  According to this aspect, the winding can be disposed at a targeted position at least at the inner corner where the overlapping of the winding is likely to occur, and as a result, the winding can be wound in an aligned state. Become. As a result, it is possible to suppress the formation of sparse unevenness due to overlapping of the windings, align the arrangement of the windings on at least the end face of the annular portion, at least the heat dissipation surface, and finish it even closer. It becomes.

  Preferably, the unevenness suppressing structure includes a slope which is provided on the heat dissipation surface and has a funnel shape from the outer circumferential side to the inner circumferential side. This unevenness suppressing structure includes a slope having a funnel shape from the outer peripheral side to the inner peripheral side of the heat radiating surface by forming the thickness on the outer peripheral side of the resin member forming the heat radiating surface thicker than the other portions of the resin member. May be. Since the heat dissipation surface is formed to be inclined from the outer peripheral side toward the inner peripheral side, the height of the resin member is higher on the outer peripheral side than on the inner peripheral side.

If the dimensions of the resin member are designed such that winding overlap occurs on the inner circumferential side of the annular portion and does not occur on the outer circumferential side, the windings can be aligned and wound. Also, the height is different between the inner and outer circumferential sides depending on the presence or absence of the overlapping of the windings generated on the end face in the finished state, and the height of the inner circumferential side becomes higher by the overlapping of the windings.
According to the above-described embodiment, the height generated by the overlapping of the windings in such a case is absorbed by the difference between the heights on the inner and outer circumferential sides, and on the heat dissipation surface in the state where the winding is finished. It is possible to make the arrangement of the windings at the point closer to flat.

More preferably, in the unevenness suppressing structure, when the cross section of the winding is circular and the winding is wound in two layers, the radius of the cross section of the winding is r, and the outer peripheral side of the resin member forming the heat dissipation surface Assuming that the difference between the thickness and the thickness on the inner circumferential side is ΔH, the following equation (1)
ΔH r r 3 3 (1)
It is formed to meet the relationship of

  By forming the thickness on the outer peripheral side of the resin member forming the heat dissipating surface thicker than the inner peripheral side based on this relational expression, the heat dissipating surface has a funnel-shaped slope from the outer peripheral side to the inner peripheral side. Ru. By forming the unevenness suppressing structure into such a shape, it is possible to absorb the thickness due to the overlapping of the windings generated on the inner peripheral side of the annular portion at the stage when the winding of the two layers is finished, two layers At the completion stage of the wound inductor, it is possible to bring the bottom surface closer to flat.

  As described above, according to the inductor of the present invention, the arrangement of the windings on the heat dissipation surface of the inductor is achieved by means of suppressing unevenness caused by overlapping of the windings on the heat dissipation surface as winding to the annular portion. Can be aligned close to each other. Thus, the heat dissipation performance of the inductor can be improved.

It is a perspective view showing the coil of one embodiment. It is a perspective view showing the state before a winding is wound by the coil of one embodiment. It is a top view showing the coil of one embodiment. It is a front view showing the coil of one embodiment, and a longitudinal section at the time of being cut in the height direction (cross-sectional view taken along the line IV-IV in FIG. 3). It is the bottom view showing the coil of one embodiment, and the perspective view seen from the bottom side. It is a longitudinal cross-sectional view (sectional view in alignment with the VI-VI line in FIG. 3) at the time of cut | disconnecting the coil of one Embodiment in the height direction in an opening position. It is an expanded longitudinal cross-sectional view (The enlarged view in the frame enclosed by the dashed-dotted line VII in FIG. 6) of the groove | channel formed in the inner peripheral angle of the annular part end surface. FIG. 5C is an enlarged view of a part of the bottom surface of the annular portion (an enlarged view in a frame surrounded by an alternate long and short dash line VIII in FIG. 5A). It is a longitudinal cross-sectional view (sectional view in alignment with the IX-IX line in FIG.8 (C)) at the time of cut | disconnecting in a height direction in the state with which the coil of 2 layer winding of one Embodiment was mounted | worn with the to-be-mounted body. It is a figure explaining the difference of the thickness by the side of the perimeter of the resin member which constitutes a lower end face of an annular part, and the thickness by the side of inner circumference.

  Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. In the following embodiments, a coil is taken as an example of an inductor, but the present invention is not limited to this example. Moreover, in order to facilitate understanding of the invention, the expressions on the drawings may include some exaggeration or deformation.

FIG. 1 is a perspective view showing a coil 1 according to an embodiment.
The coil 1 accommodates a toroidal core 4 (hidden in FIG. 1) in a bobbin 2 formed of resin, and winds a winding 20 (only a part of which has a reference numeral) along the outer surface of the bobbin 2 Configuration. For this purpose, the bobbin 2 has an annular portion 6, which is annularly formed and has a space for accommodating the toroidal core 4 therein. The bobbin 2 also has two arm portions 10, which extend outward (laterally) from the outer peripheral surface 28 of the annular portion 6. The coil 1 is mounted as an electronic component on a mounting body, and is used in a fixed state by a fixing member such as a screw, for example.

  The arm 10 is a portion for fixing the coil 1 as described above. For this reason, fixing holes 12 are formed at the end of the arm portion 10, and a metal collar 14 is embedded in each of the fixing holes 12. The coil 1 can be screwed to the mounting object through the fixing holes 12 (specifically, the collar 14). In addition, at the end of each arm 10, a positioning hole 16 is formed adjacent to the fixing hole 12. These positioning holes 16 are for positioning with a mounting object at the time of screwing.

  More specifically, the arm portion 10 has two flat plate-like insulating walls 18 and a support wall 24, and the two insulating walls 18 are proximal to the outer circumferential surface 28 of the annular portion 6. Are connected and extend outward. The support wall 24 is formed at a position where it is sandwiched between just two insulating walls 18, and its proximal end is also connected to the outer peripheral surface 28. The insulating wall 18 and the support wall 24 are disposed on the outer circumferential surface 28 so as to rise in the direction of the central axis of the coil 1. Further, although not shown in FIG. 1, a plate-like portion extending in the direction orthogonal to the insulating wall 18 and the support wall 24 is formed between the insulating wall 18 and the support wall 24.

  A bearing board 26 is formed at the tip of the arm 10, and the bearing board 26 has a flat plate shape extending in a direction (parallel to the end face of the annular portion 6) orthogonal to the central axis of the coil 1. The fixing holes 12 and the positioning holes 16 are formed through the bearing board 26 in the thickness direction. The bearing board 26 is supported by the support wall 24 and the insulating walls 18 on both sides thereof.

FIG. 2 is a perspective view showing a state before the winding 20 is applied to the coil 1 of the embodiment.
As shown in FIG. 2, a part of the resin forming the upper end face 30 t of the annular portion 6 and the outer peripheral surface 28 is broken away, the toroidal core 4 is accommodated in the annular portion 6 in close contact with the inner surface. . The toroidal core 4 is formed of a magnetic material such as dust core, pure iron, sendust, ferrite, amorphous, laminated steel plate or the like. An accommodating portion 6 is formed on the outer surface of the toroidal core 4 by a thermoplastic resin such as PPS (polyphenylene sulfide). The peripheral surface of the housing portion 6 is formed to have a thickness of about 0.8 to 1.5 mm, but a desired thickness can be appropriately selected and formed according to the required strength.

  In the coil 1 of the present embodiment, the bobbin 2 and the toroidal core 4 are integrally molded through insert molding, and the annular portion 6 and the arm portion 10 are resin-molded also on the bobbin 2 in the molding process. Therefore, no gap is present between the annular portion 6 of the bobbin 2 and the toroidal core 4 in the completed state. Further, a collar 14 disposed inside the fixing hole 12 is also integrally formed on the arm portion 10 of the bobbin 2, and the collar 14 is embedded in the fixing hole 12 in advance and in close contact therewith. That is, the resin-made bobbin 2 is integrally molded with the metal-made toroidal core 4 and the collar 14.

In integral molding, in addition to PPS used in this embodiment, for example, resins such as epoxy resin, unsaturated polyester resin, urethane resin, BMC (bulk molding compound), PBT (polybutylene terephthalate), etc. can be used. It is.
The integral molding will be described in detail later. Further, unless otherwise specified in the following description, the coil 1 in a state before the winding 20 is wound will be described.

FIG. 3 is a plan view showing the coil 1 of one embodiment.
As described above, the annular portion 6 is formed in an annular shape, and the outer periphery and the inner periphery of the upper end surface 30t are formed in a substantially circular shape. Two arms 10 are arranged at substantially equal intervals on the outer periphery of the annular portion 6, and are provided so as to extend outward. As is apparent from the relationship with the horizontal dashed dotted line passing through the center of the annular portion 6 in FIG. 3, the insulating wall 18 forming the root of each arm 10 has a predetermined angle with respect to the radial direction of the outer periphery It is continuous with the outer peripheral surface 28 of the annular portion 6.

  A plurality of guide grooves 40 are arranged in the circumferential direction on the inner peripheral side of the upper end surface 30t, that is, on the inner peripheral angle 34n which is a corner portion formed continuously between the upper end surface 30t and the inner peripheral surface 32. It is formed. The guide groove 40 is a recess for guiding the winding 20 to be wound in alignment along the outer surface of the annular portion 6. The circumferential length of the upper end face 30t is shorter on the inner circumferential side than on the outer circumferential side, and the space for winding the winding 20 is so narrow. Therefore, the winding 20 increases with the increase in the number of turns near the inner corner. It becomes easy to overlap. At this time, if the degree of overlapping of the windings 20 in the state of the end of winding is not uniform, irregular asperities occur on the end face of the coil 1 (the surface formed by the assembly of the windings 20). For this reason, even if a heat dissipation member (not shown in FIG. 3) is disposed to face the end face when the coil 1 is used, the heat released by the coil 1 can not be efficiently transmitted to the heat dissipation member. In order to avoid the performance degradation of the coil 1 due to overheating, it is necessary to improve the heat dissipation performance of the coil 1, so the end face of the coil 1 is finished as flat as possible so as to be able to contact the heat dissipation member in a wider area. Is desirable.

  Therefore, in the coil 1 of the present embodiment, the guide groove 40 is formed at the inner circumferential angle 34 n, and the arrangement of the winding 20 at the targeted position is enabled, whereby alignment of the winding 20 with winding is achieved. We are trying to promote. This makes it possible to finish the end face in a more uniform and flat state without irregular irregularities being formed on the end face of the coil 1. As a result, the heat released from the coil 1 can be efficiently spread over the heat dissipation member, and the heat dissipation performance of the coil 1 can be improved. The alignment of the windings 20 will be described in more detail later.

  The fixing hole 12 of the arm 10 is used when fixing the coil 1 to the mounting object as described above. The collar 14 embedded inside the fixing hole 12 reinforces the fixing hole 12 when screwing. The collar 14 is made of resin, iron, alloy or the like. Further, the positioning using the positioning hole 16 can be performed, for example, by causing a boss provided on the mounting body to penetrate the positioning hole 16.

  The positioning holes 16 provided one by one in each arm portion 10 are different in shape, and one of them is formed in a substantially regular circle and the other in an elliptical shape. As described above, by making the positioning hole 16 into a shape with a slight play, it is possible to allow a slight positional deviation and to make the boss easy to penetrate, and the coil 1 can be easily attached to the mounting object I have to.

Drawing 4 is a figure showing coil 1 of one embodiment from the front side. Here, (A) in FIG. 4 shows a front view of the coil 1 and (B) in FIG. 4 shows a longitudinal sectional view.
In FIG. 4 (A): the insulating wall 18 of the arm portion 10 has its base end spread over the entire area seen in the height direction of the outer peripheral surface 28 of the annular portion 6 and has a tapered shape from the base end to the tip I am The bearing board 26 is connected to the tapered tip portion of the insulating wall 18.

  Further, the insulating wall 18 is formed to have an equal width (same height) from the base end to a certain extent at the lower end position of the outer peripheral surface 28, and the equal width part protrudes from the lower end surface 30 b of the annular portion 6 It extends downward. Such a shape is for securing the insulation distance between the toroidal core 4 housed inside the annular portion 6 and the winding 20 (not shown in FIG. 4) wound around the outer surface of the annular portion 6. The securing of the insulation distance will be described later again.

  An outer peripheral angle 34g, which is a corner portion connected between the end surface 30 of the annular portion 6 and the outer peripheral surface 28, is formed into a substantially arc-shaped smooth curved surface. This shape allows the winding 20 to be wound along the outer peripheral surface 28 without damaging the winding 20.

  In FIG. 4 (B): Here, a cross section (cross section taken along the line IV-IV in FIG. 3) when the coil 1 is cut in the height direction by a line passing through the center points of the annular portion 6 and the collar 14 Indicates As apparent from this figure, the toroidal core 4 is housed in close contact with the inner surface of the annular portion 6 without any gap. Further, the collar 14 is in close contact with the inner surface of the fixing hole 12 formed in the bearing board 26 provided in the arm portion 10. The bobbin 2 is integrally molded together with the toroidal core 4 and the collar 14 by insert molding using a mold in which the toroidal core 4 and the collar 14 are set in advance. Therefore, unlike the structure in which the bobbin and the core are separate members, no gap is generated between the annular portion 6 and the toroidal core 4, and the space between them is filled with the resin forming the annular portion 6. .

  In the case where a two-part type bobbin comprising an annular portion and a lid portion is used as a comparative example to the present embodiment, some space continues to be maintained between the core and the bobbin even after the core is accommodated. Due to the presence of this space, the strength of the bobbin with respect to the winding depends on the thickness of the resin forming the bobbin, so there is a concern of cracking or damage. On the other hand, if the bobbin 2 and the toroidal core 4 are integrally molded as in the coil 1 of the present embodiment, a gap is not generated between the two, and therefore, the concern of strength as described above is released. Furthermore, the bobbin 2 integrally molded can accommodate the toroidal core 4 of larger volume by the part without a clearance gap. In other words, when the dimension of the core is the same as that of the two-part type bobbin, it is possible to exhibit the same characteristics as the core while reducing the external dimension of the bobbin.

  In the present embodiment, the collar 14 is integrally formed in addition to the toroidal core 4 and the bobbin 2. As a result, only one mold is used for molding, and the collar 14 closely adheres to the resin forming the fixing hole 12 simultaneously with the molding of the bobbin 2, so the manufacturing is compared to the case where the bobbin and the collar are assembled separately. Efficiency can be improved and costs can be reduced. Further, the provision of the collar 14 in the fixing hole 12 reinforces the fixing hole 12 and the strength of the hole is further enhanced.

  The curve (so-called "R") of the inner circumferential angle 34n, which is a corner part connected between the end face 30 of the annular portion 6 and the inner circumferential surface 32, is gentler than the outer circumferential angle 34g, and The bulge is scraped off and formed into a shape that is recessed inward. This is because the guide groove 40 is provided at the inner circumferential angle 34 n. The shape of the guide groove 40 will be described in detail later.

Drawing 5 is a figure showing coil 1 of one embodiment from the bottom side. Here, (A) in FIG. 5 is a bottom view of the coil 1, and (B) in FIG. 5 is a perspective view seen from the bottom side.
In (A) of FIG. 5: like the upper end face 30t, a guide groove is formed at the inner circumferential angle 34n also at the lower end face 30b. Further, at the lower end of the corner portion connected between the insulating wall 18 and the outer peripheral surface 28, the insulating wall 18 projects downward below the lower end surface 30b and is formed so as to cover the outer peripheral angle 34g of the lower end surface 30b. There is.

  In FIG. 5 (B): As shown in this figure, an opening 8 is partially formed in the outer peripheral surface 28 of the annular portion 6, and the opening 8 corresponds to just two insulating walls 18 and a support wall 24. At a position (two places per one arm portion 10), it is located closer to the lower end thereof. The opening 8 is not covered with the resin and is open to the outside, so the surface of the toroidal core 4 accommodated in the annular portion 6 is exposed to the outside through the opening 8. Such an opening 8 is necessarily produced when the bobbin 2 is insert-molded.

[Securing insulation distance with opening]
FIG. 6 is a longitudinal sectional view (sectional view taken along the line VI-VI in FIG. 3) when the coil 1 of one embodiment is cut in the height direction at the position where the opening 8 is formed. In this figure, in order to facilitate understanding of how the opening 8 is formed on the outer surface of the annular portion 6, in the molding die 22 used for insert molding, only the portion forming the lower portion of the annular portion 6 is In fact, it has formed the shape which covers the bobbin 2 whole.

  In the process of insert-molding the bobbin 2, first, the toroidal core 4 is set at a predetermined position of the molding die 22, and then the resin forming the bobbin 2 is injected and filled from above the molding die 22. Two claws for positioning the toroidal core 4 are formed on both sides of the molding die 22 in advance. Since the toroidal core 4 is pressed downward by the injection pressure of the resin by injecting the resin from the upper side, the toroidal core 4 can be stably supported only by the claws located on the lower side. The contact (corresponding to the mark of the claw) between the claw of the molding die 22 and the toroidal core 4 formed as a result of molding in this manner is the opening 8. Since the toroidal core 4 is supported from below by the claws of the molding die 22, the opening 8 is formed near the lower end of the outer peripheral surface 28. When the filled resin is solidified, the bobbin 2 integrally formed with the toroidal core 4 and the collar 14, that is, the coil 1 before the winding 20 is applied is taken out from the molding die 22. At this time, there is nothing to cover the opening 8 which is a contact point between the molding die 22 and the toroidal core 4, and the toroidal core 4 is exposed to the outside.

  Thus, since the toroidal core 4 is exposed to the outside, it is necessary to secure a sufficient insulation distance between the bobbin 2 and the winding wire 20. Therefore, in the bobbin 2 of the present embodiment, two insulating walls 18 are provided on both sides of the opening 8 as viewed in the circumferential direction, and the opening 8 and the winding region of the winding 20 are separated. Thereby, it becomes possible to secure the insulation distance specified in various safety standards.

  By the way, the arm portion 10 plays a role of connecting the bearing board 26 used for mounting the coil 1 to the mounted body to the annular portion 6 and is indispensable. The insulating wall 18 also plays a role in securing the insulating distance between the toroidal core 4 and the winding 20 as described above, and is an indispensable member. If the arm portion 10 and the insulating wall 18 are provided separately, a space for connecting each to the outer peripheral surface 28 is required. In this case, since the space for applying the winding wire 20 to the annular portion 6 is reduced by the necessary space and the number of windings is reduced, the performance degradation as a coil can not be avoided. Further, the arm portion 10 is present only to support the bearing board 26 and its root portion becomes a dead space.

  Therefore, in the coil 1 of the present embodiment, the insulating wall 18 doubles as the root of the arm 10, thereby effectively utilizing the part that can be a dead space, and at the same time, the minimum necessary across the opening 8 in the outer peripheral surface 28. Other than the area, the area for the winding 20 can be allocated. As a result, it is possible to secure a sufficient space for winding the winding wire 20 in the annular portion 6 and to exhibit desired performance as a coil.

[Guide groove]
FIG. 7 is an enlarged view of the guide groove 40 formed at the inner circumferential angle 34 n (in a frame surrounded by an alternate long and short dash line VII in FIG. 6).
(A) in FIG. 7: Here, the inside of a region VII surrounded by an alternate long and short dash line in FIG. 6 is shown enlarged. As shown in this figure, a plurality of guide grooves 40 are provided at the inner circumferential angle 34 n so as to be continuous in the circumferential direction. Each of the guide grooves 40 is formed in such a shape that a part of a surface continuous from an end closer to the inner circumferential surface 32 of the end face 30 to an end closer to the end 30 of the inner circumferential surface 32 is cut and recessed .

  Generally, when winding a winding around a bobbin (toroidal core), the winding is brought into contact with the inner circumferential angle and winding is started from the inner circumferential side of the bobbin. At this time, since the space is narrower on the inner peripheral side than the outer peripheral side and the windings are densely packed, irregular winding is likely to occur even in a single-layered coil in which it is desirable that the windings do not overlap. In addition, when the winding is wound and expanded, it is likely to be in a floating state with almost no contact with the outer surface of the bobbin.

  According to the present embodiment, when winding the winding 20 around the outer surface of the annular portion 6, the winding 20 can be pressed against the guide groove 40 and the winding can be started in a state of being firmly fitted in the groove. If 40 is the starting point of winding, the work becomes easier. Further, by fitting the lower part of the winding 20 into each guide groove 40, the inner circumferential angle 34 n can be aligned at the position aimed at the winding 20, and irregular overlapping of the windings 20 can be prevented. In addition, the winding 20 can be reliably brought into contact with the inner circumferential angle 34 n to suppress the floating due to the winding expansion of the winding 20.

  (B) in FIG. 7: Here, the inside of a region VII surrounded by an alternate long and short dash line in FIG. 6 is shown as an end view. This end surface corresponds to the cut surface of the deepest portion of the groove in the guide groove 40. In the present embodiment, the resin members constituting the end surface 30 and the inner circumferential surface 28 of the annular portion 6 are each formed to have a thickness w. Further, for reference, an arc having a radius w centered at o which is a point on the outer peripheral edge (edge) of the toroidal core 4 is represented in the figure by a two-dot chain line.

  As shown in this figure, the deepest portion of the guide groove 40 is formed at a position deeper than this arc. Further, one end p of the side ps forming the deepest portion of the guide groove 40 is located at an end near the inner circumferential surface 32 of the end face 30 and the other end q is located at an end near the end face 30 of the inner circumferential surface 32 There is. That is, the side pq is the end of the end face 30 and the side rs is the side produced by scraping the end of the inner circumferential surface 32, and the guide groove 40 remains at the connection between the end face 30 and the inner circumferential surface 32. It can be seen that it is formed to the area before and after that. By forming the guide groove 40 in such a shape, the winding 20 can easily follow the guide groove 40, and the winding 20 can be aligned at the connection between the end surface 30 and the inner circumferential surface 32 where the winding 20 is most likely to overlap. Placement and height adjustment are possible.

  The dimensions of the individual guide grooves 40 are designed such that the width is as large as or larger than the diameter of the winding 20 and the depth is such that the end face of the coil 1 after winding the winding 20 is flat. More specifically, the depth of the guide groove 40 is designed to be equal to or less than the radius of the winding 20 in order to align the windings 20 adjacent to each other at the inner circumferential angle 34 n. And in order to make winding 20 fit in more stably, the shape of the arc which forms the cross section of guide groove 40 is the lower part of the cross section of winding 20 which will contact the surface of guide groove 40. It is preferable that it is the same shape as the arc which forms.

[Alignment of winding]
FIG. 8 is an enlarged view (in a region VIII surrounded by an alternate long and short dash line in FIG. 5A) showing a part of the bottom surface of the annular portion 6. The principle of aligning and arranging the windings 20 by the guide grooves 40 will be described below, taking the case of winding the windings 20 in two layers as an example.

  (A) in FIG. 8: is an enlarged view of a state in which the winding 20 is not wound. As shown in this figure, in the present embodiment, the guide groove 40 is formed only at the inner circumferential angle 34 n and is not formed at the outer circumferential angle 34 g. Further, it can be seen that the guide groove 40 is formed from the end near the inner peripheral surface 32 of the lower end surface 30 b to the inner peripheral surface 32.

  (B) in FIG. 8 is an enlarged view of a state in which the first layer winding 20a has been wound. By fitting the first layer winding 20a into the guide groove 40, the winding 20 does not overlap at the inner circumferential angle 34n, and the winding 20a is neatly arranged in the circumferentially adjacent state. From the inner circumferential angle 34n to the outer circumferential angle 34g, it can be seen that the windings 20 are wound radially at substantially equal intervals along the lower end surface 30b.

  (C) in FIG. 8: It is an enlarged view of the state which finished winding the winding 20b of the 2nd layer. The second layer winding 20b does not fit in the guide groove 40, and the first layer winding 20a aligned and disposed at the inner circumferential angle 34n is arranged to aim at an intermediate position adjacent to one another. . The winding 20b of the second layer, which is accommodated between the windings 20a of the first layer adjacent to each other, radiates so as to stitch between the windings 20a of the first layer adjacent from the inner circumferential angle 34n to the outer circumferential angle 34g. Are wound at approximately equal intervals. As a result, the outer peripheral angle 34g in a state in which the second layer winding 20b is finished turns to a state in which the first layer winding 20a and the second layer winding 20b are alternately wound at substantially equal intervals, The winding 20a and the winding 20b do not overlap.

[Slope of end face]
FIG. 9 is a longitudinal sectional view (IX-IX in FIG. 8C) in the case where the annular portion 6 is cut in the height direction in a state in which the coil 1 of two-layer winding in one embodiment is attached to the mounting object. (Cross-sectional view along the line). Here, in order to make it easy to understand how the first layer winding 20a and the second layer winding 20b are wound, the inner circumferential surface 32 of the annular portion 6 which should originally be represented on the left side of the drawing and there is The appearance of the winding 20 wound around is simplified to be not shown.

  When the winding 20 is wound in two layers, the second layer winding 20b is placed and stored between the adjacent first layer windings 20a at the inner circumferential angle 34n. Therefore, the height near the inner circumferential angle 34n at the completion of the coil 1 is necessarily higher than that near the outer circumferential angle 34g by the amount that the first layer winding 20a and the second layer winding 20b align and overlap. .

  So, in this embodiment, the thickness of the outer peripheral side of lower end face 30b is formed thicker than the inner peripheral side. Looking at the cross section of the annular portion 6, the thickness of the resin member constituting the lower end surface 30b is the thickest at the outermost edge, and gradually decreases from the outer peripheral side to the inner peripheral side. It has a funnel shape toward the circumferential side, and is in a state of being inclined upward. Thereby, the height generated by the overlapping of the first layer winding 20a and the second layer winding 20b at the inner circumferential angle 34n is the inclination of the lower end surface 30b (the thickness of the inner peripheral side and the outer peripheral side of the resin member Difference) is absorbed. As a result, it is possible to make the bottom of the two-layer coil 1 flatter when the coil 1 is completed.

  Generally, when the coil 1 is mounted on the mounting object, a heat dissipation member is disposed to face the end face of the coil 1 as a heat dissipation countermeasure. For example, as shown in FIG. 9, the heat dissipation sheet 36 and the heat sink 38 are disposed in parallel with each other at a position facing the bottom surface of the coil 1. As a result, the heat released by the coil 1 can be transmitted to the heat dissipation sheet 36, and the heat transferred by the heat dissipation sheet 36 can be dissipated to the heat sink 38, effectively lowering the temperature around the coil 1 and the coil 1 It becomes possible.

  At this time, if irregular irregularities (partially large projections and partial indentations) are formed on the bottom surface of the coil 1, spots of large and small amount of heat radiation are generated locally. The heat emitted by the coil 1 can not be efficiently transmitted to the heat dissipation member, and a good heat dissipation performance can not be obtained. As in the present embodiment, by forming the end face of the side facing the heat dissipation member of the coil 1 close to flat, it is possible to make this end face substantially parallel to the heat dissipation member, and as a result, the heat emitted by the coil 1 It is possible to uniformly distribute the heat dissipation member evenly to the heat dissipation member and improve the heat dissipation performance of the coil 1.

  FIG. 10 is a view for explaining the difference between the thickness on the outer peripheral side and the thickness on the inner peripheral side of the resin member constituting the lower end surface 30 b of the annular portion 6.

  In FIG. 10 (A): The winding 20 overlaps in the vicinity of the inner circumferential angle 34 n when the coil 1 is a two-layer wound coil, which corresponds to three turns of the winding 20 (of which two turns are the first layer winding 20a, the first turn is a winding 20b of the second layer). As shown in this figure, in the two-layer coil 1 according to this embodiment, a winding 20 having a substantially circular cross section is used. Although the inner circumferential angle 34n is not shown in the figure, when the winding 20 is wound around the annular portion 6, the lower portion of the first layer winding 20a is provided at the inner circumferential angle 34n. It will fit in the guide groove 40.

  First, the respective turns of the first layer winding 20a are arranged adjacent to each other, and are wound spirally in the circumferential direction of the annular portion 6. When the first layer is finished, the second layer winding 20b is disposed in the valley formed by two turns of the first layer winding 20a adjacent to each other at the inner circumferential angle 34n. That is, the winding 20b of the second layer contacts the turns of the winding 20a of the first layer near the inner circumferential angle 34n. Thus, when the second layer is finished, the second layer winding 20b is arranged in alignment on the first layer winding 20a, so that the winding 20 is equalized in the vicinity of the inner circumferential angle 34n. Can be overwhelmed. At this time, as shown in FIG. 10A, assuming that the radius of the cross section of the winding 20 is r, the height Hn formed by the windings 20 for two layers in the vicinity of the inner circumferential angle 34n is 2 + √3) r.

  In FIG. 10 (B): The state of the winding 20 in the vicinity of the outer peripheral angle 34g when the coil 1 is a two-layer winding coil, winding 20 for three turns (of which two turns are the first layer winding 20a, The first turn is the second layer winding 20b). Since the outer circumferential angle 34g has a space in comparison with the inner circumferential angle 34n, a space is formed between the turns formed by the first layer winding 20a at substantially equal intervals when the first layer has been wound. Is left. The second layer winding 20b is arranged to aim at this space, so that even when all the two layers of the winding 20 have been completely wound, no overlapping occurs at the outer peripheral angle 34g. Therefore, as shown in (B) in FIG. 10, the height Hg formed by the windings for two layers in the vicinity of the outer peripheral angle 34g is 2r.

  Thus, in the coil 1 of the two-layer winding, the height generated by the windings 20 for two layers is the second layer compared to the height Hg near the outer peripheral angle 34g in the height Hn near the inner peripheral angle 34n. Is increased by r√3 which is caused by the overlapping of the windings 20b. In consideration of the swelling and swelling here, it may be larger than r√3. That is, in the difference ΔH between the height Hn near the inner circumferential angle 34n and the height Hg near the outer circumferential angle 34g, the relationship ΔH ≒ Hn−Hg ≧ r√3 holds.

  (C) in FIG. 10: This is a part of a longitudinal sectional view of the annular portion 6 cut in the height direction, and corresponds to the lower portion of the annular portion 6 shown in FIG. In the two-layer coil 1 of the present embodiment, the thickness of the resin member constituting the lower end surface 30b of the annular portion 6 is adjusted in order to make the bottom surface disposed opposite to the heat dissipation member flatter at the finish stage. The thickness on the outer peripheral side is formed larger than the thickness on the inner peripheral side by the difference ΔH (note that if the difference Δd is provided in the depth of the groove between the inner periphery and the outer periphery, ΔH is added to ΔH). By forming such a shape, it is possible to absorb the difference in height of the winding 20 in the vicinity of the inner circumferential angle 34 n and the outer circumferential angle 34 g caused by the difference in the winding overlap of the winding 20. This makes it possible to bring the bottom of the coil 1 close to flat.

  As described above, according to the coil 1 of the present embodiment, by forming a plurality of guide grooves at the inner circumferential angle 34 n of the annular portion 6, the winding 20 can be disposed at the targeted position, The winding 20 can be aligned in the end-of-winding state to suppress the irregular asperity that may occur due to the overlapping of the end face 30 and make the end face 30 flatter.

  Further, in the case of a coil 1 of two-layer winding, in the case where the dimensions of the bobbin 2 are designed such that the windings 20 overlap only on the inner circumferential side of the annular portion 6 and not on the outer circumferential side, The lower end surface 30b of the end surface 30 disposed opposite to the heat dissipation member is formed into a funnel shape which is inclined upward from the outer peripheral side toward the inner peripheral side, thereby causing the winding 20 to overlap on the inner peripheral side The height can be absorbed by the inclination of the lower end surface 30b. As a result, when the coil 1 is completed, it is possible to bring the bottom surface closer to flatter.

The present invention can be variously modified and carried out without being limited to the above-described embodiment.
For example, although a coil was taken and explained as an example of an inductor using a toroidal core, it is applicable also to a reactor etc.

The guide groove 40 can have a preferable shape and a suitable groove depth depending on the thickness of the winding 20, the number of layers to be wound, and the like. In the coil 1 according to the above-described embodiment, the guide groove 40 is formed at the upper and lower inner circumferential angles 34n, but at least the inner circumferential angle 34n of the lower end face 30b disposed opposite to the heat dissipation member For example, the end face at the completion of the coil 1 can be made to be flat and contributed to the improvement of the heat radiation efficiency.
Conversely, in addition to the inner circumferential angle 34n, the guide groove 40 may be formed at the outer circumferential angle 34g. By forming the guide grooves 40 at the corners 34 on both sides, the winding wire 20 can be wound in a more aligned state, and it becomes possible to make the end face of the completed coil 1 closer to flat even more reliably. .

  And although the shape and the dimension of the guide groove 40 are designed and formed so that the windings 20 may be adjacent to each other at the inner circumferential angle 34n, a gap may be provided appropriately according to the situation. In addition, some gaps may occur due to manufacturing circumstances and the like.

  The bobbin 2 used was one in which the collar 12 and the toroidal core 4 were integrally formed, but these members do not necessarily have to be integrally formed. For example, the collar may be fitted to a preformed bobbin. In addition, the core can be accommodated in a two-part type bobbin constituted of an annular portion and a lid portion.

  The strength of the fixing hole 12 is improved by integrally molding the collar 14 inside the fixing hole 12. However, when sufficient strength can be obtained, the fixing member can be formed only by the fixing hole 12 without using the collar 16. You may accept. Further, although the positioning hole 16 is provided in the vicinity of the collar 14, the positioning hole 16 is not necessarily formed at this position, and a preferable position can be appropriately selected.

1 coil (inductor)
2 Bobbin (resin member)
4 Toroidal core (core)
6 annular part 8 opening 10, 50, 70 arm 12, 52, 72 fixing hole 14, 54, 74 collar 16, 56, 76 positioning hole 18, 58, 78 insulating wall 18f, 58f, 78f front insulating wall 18b, 58b , 78b Rear insulating wall 20 winding, 20a first layer winding, 20b second layer winding 22 molding die 24 support wall 26, 66, 86 bearing board 28 outer peripheral surface 30 end surface, 30t upper end surface, 30b lower End face (heat dissipation surface)
32 inner circumferential surface 34 angles, 34 n inner circumferential angle, 34 g outer circumferential angle 36 heat dissipation sheet 38 heat sink 40 guide groove

Claims (5)

An annularly formed core,
And a resin member covering at least a part of the surface of the core,
The resin member is
It has a heat dissipation surface arranged to be opposed to the heat dissipation member as one of two end surfaces formed in a pair in the axial direction of the annular portion in which the winding is wound, and the winding is disposed on the heat dissipation surface And an unevenness suppressing structure for suppressing unevenness caused by overlapping .
The unevenness suppressing structure is
The thickness on the outer peripheral side of the resin member forming the heat dissipating surface is formed thicker than the other portion of the resin member, thereby including a slope having a funnel shape from the outer peripheral side to the inner peripheral side of the heat dissipating surface. Characteristic inductor. In the inductor according to claim 1,
The unevenness suppressing structure is
Among the corner portions on the inner peripheral side continuous between the inner peripheral surface of the annular portion and the end surface adjacent to each other, at least the corner portions connected to the heat dissipation surface are formed to promote alignment of the windings. An inductor characterized by including a groove. In the inductor according to claim 2,
The unevenness suppressing structure is
Among the corner portions on the outer peripheral side continuous between the outer peripheral surface of the annular portion and the end surface adjacent to each other, a plurality of grooves formed at least at the corner portions connected to the heat dissipation surface to promote alignment of the winding An inductor further comprising. The inductor according to any one of claims 1 to 3
The unevenness suppressing structure is
An inductor characterized in that it comprises a slope which is provided on the heat dissipation surface and which forms a funnel shape from the outer peripheral side to the inner peripheral side. In the inductor according to any one of claims 1 to 4 ,
The unevenness suppressing structure is
When the cross section of the winding is circular and the winding is wound in two layers, the radius of the cross section of the winding is r, the thickness on the outer peripheral side of the resin member forming the heat dissipating surface and the inner peripheral side Let ΔH be the difference between the thickness of
ΔH r r 3 3 (1)
An inductor characterized by satisfying the following relationship: