JP2016100538A - choke coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a choke coil that allows for ensuring electric insulation between a wound portion and an installation object.SOLUTION: A choke coil 1α comprises: an outer core 2 that is formed by a cylindrical-shaped magnetic substance having opening portions on one end and the other end, and includes an internal space formed into a rectangular parallelepiped shape; an inner core 3 that is formed by a columnar magnetic substance and disposed with one end face 3L and the other end face 3R thereof made to face two planes of the inner circumferential faces of the outer core 2 facing each other; and a coil 4 that is formed by winding a winding wire and includes a wound portion 40 disposed on the outer circumference of the inner core 3, the choke coil 1α being mounted on an installation object with opening end faces 2D, 2U on the one end side of the outer core 2 made to face the installation object. The choke coil 1α comprises an electric insulation layer 6 that closes the entire opening portion of opening end face 2D on the one end side, extending over the opening end face 2D.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a choke coil used mainly for boosting a power supply circuit, improving a power factor, or current smoothing.

  The choke coil is used, for example, for boosting a power supply circuit, for power factor improvement, or for current smoothing. For example, a choke coil formed by combining a pair of E-shaped split cores is known. In this choke coil, a coil in which a winding is wound around a leg piece at the center of the E-shape of the split core is disposed. However, the split core of this choke coil has many bent portions, and stress tends to concentrate on the bent portion, so that the split core may be damaged when the split core is handled.

  In view of the above problems, the choke coil of Patent Document 1 has been proposed. The choke coil is a choke coil in which a magnetic core is configured by a cylindrical outer core having an inner space formed in a rectangular parallelepiped shape and a columnar inner core disposed inside the outer core. The one end surface and the other end surface of the inner core are respectively disposed to face two opposing planes of the inner peripheral surface of the outer core, and a coil is provided on the outer periphery of the inner core via a bobbin. . This choke coil is fixed in a state in which one open end surface of the outer core is in contact with an installation target (indicated as a heat radiating member in Patent Document 1). Further, in this choke coil, a heat radiating layer composed of a heat radiating sheet or a mold resin is formed between the winding portion inside the outer core and the installation target, and the heat generated by the choke coil is radiated from the heat radiating layer. The structure which escapes to an installation target object is adopted. The outer core and the inner core of the choke coil having the above configuration have a very simple shape, are easy to manufacture, and have no portion where stress is likely to concentrate, and are easy to handle.

JP 2013-51402 A

  In recent years, choke coils used in remarkable developments such as hybrid cars and electric cars carry large currents, so it is necessary to ensure more reliable electrical insulation between the winding section and the installation object. It is done.

  In response to such a request, in the choke coil of Patent Document 1, since only a heat radiation layer is provided between the winding part and the installation target object, the electric power between the winding part and the installation target object is determined. It is required to improve the insulation performance.

  Therefore, in view of the above circumstances, a choke coil that can ensure electrical insulation between a winding portion and an installation target is provided.

  A choke coil according to an aspect of the present invention is configured by a cylindrical magnetic body having openings at one end and the other end thereof, and is configured by an outer core formed in a rectangular parallelepiped shape and a columnar magnetic body. Each of the one end face and the other end face is formed by winding an inner core disposed to face two opposing planes of the inner peripheral face of the outer core, A coil having a winding portion disposed on the outer periphery of the core, and the choke coil placed on the object to be installed with the opening end face on the one end side of the outer core facing toward the installation target, The whole opening part in the opening end surface on the side is closed, and an electrical insulating layer extending to the opening end surface is provided.

  According to the choke coil, it is possible to ensure electrical insulation between the coil winding portion of the choke coil and the installation target.

1 is a schematic perspective view of a choke coil according to a first embodiment. It is II-II sectional drawing of FIG. It is III-III sectional drawing of FIG. FIG. 3 is a partially enlarged view of FIG. 2. It is explanatory drawing of the process (alpha) in the manufacturing method of the choke coil of Embodiment 1. FIG. It is explanatory drawing of process (beta) in the manufacturing method of the choke coil of Embodiment 1. FIG. It is explanatory drawing of process (gamma) in the manufacturing method of the choke coil of Embodiment 1. FIG. FIG. 6 is a longitudinal sectional view of a choke coil according to a second embodiment.

-Description of embodiment of this invention First, the embodiment of this invention is listed and demonstrated.

<1> The choke coil according to the embodiment includes a cylindrical magnetic body having openings at one end and the other end, and includes an outer core whose inner space is formed in a rectangular parallelepiped shape, and a columnar magnetic body. One end surface and the other end surface of each of the inner cores are arranged by facing two opposing planes of the inner peripheral surface of the outer core, and the inner core is formed by winding a winding. A coil having a winding portion disposed on the outer periphery of the choke coil, the choke coil being placed on an object to be installed with the opening end face on one end side of the outer core facing toward the installation target. And an electrical insulating layer covering the entire opening end surface and covering the opening end surface.

  The electrical insulation between the winding part of a coil and an installation target object can be ensured by closing the whole opening part with an electrical insulation layer like the said structure. In particular, when the electrical insulating layer reaches the opening end face on one end side of the outer core, electrical insulation between the coil winding portion and the installation target can be further ensured.

<2> As the choke coil according to the embodiment, the electrical insulating layer may be an insulating sheet that is disposed on the opening end face and has a size that covers the entire opening end face in addition to the opening.

  By covering the entire opening end face with the insulating sheet, electrical insulation between the coil winding portion and the installation target can be more reliably performed. Moreover, according to the said structure, since an electrical insulation layer can be formed only by arrange | positioning an insulating sheet to an opening end surface, the productivity of a choke coil can be improved.

<3> As the choke coil according to the embodiment, a heat dissipation layer that is in contact with both the electrical insulation layer and the winding portion is provided between the electrical insulating layer and the outer peripheral surface of the winding portion. The form whose heat conductivity is 0.2 W / m * K or more can be mentioned.

  By forming the heat dissipation layer separately from the electrical insulating layer, the heat generated in the choke coil when the choke coil is used can be efficiently released to the installation object. As a result, adverse effects on the choke coil due to heat can be suppressed.

<4> As the choke coil of the embodiment including the heat dissipation layer, a form in which the distance between the outer end of the winding portion on the electric insulating layer side and the electric insulating layer is 7 mm or less can be given.

  The above distance is the shortest distance between the winding portion and the electrical insulating layer. By setting the thickness of the heat dissipation layer at the shortest distance to 7 mm or less, the heat dissipation layer does not become too thick, and the heat dissipation from the winding part to the installation object through the heat dissipation layer is effectively performed. Can do.

<5> As the choke coil of the embodiment including the heat dissipation layer, the heat dissipation layer is a heat dissipation sheet compressed between the electrical insulating layer and the outer peripheral surface of the winding portion, and among the heat dissipation sheets, Assuming that the thickness of the uncompressed portion is t1, and the thickness of the most compressed portion is t2, a form satisfying t1−t2 ≦ 0.7 × t1 can be given.

  By forming the heat dissipation layer with a heat dissipation sheet, the formation of the heat dissipation layer can be facilitated. This is because the heat dissipation layer can be formed simply by attaching the heat dissipation sheet on the electrical insulating layer. Here, t1-t2 is the maximum compression amount of the heat dissipation layer of the heat dissipation sheet. When the maximum compression amount is 0.7 × t1 or less, the characteristics of the heat dissipation sheet before compression are not impaired by the compression.

<6> As the choke coil of the embodiment in which the heat dissipation layer is a heat dissipation sheet, when the winding is a round wire and the diameter of the cross section of the round wire is d, 0.5 × d ≦ t1-t2 The form which fills can be mentioned.

  T1-t2 that is the compression amount of the heat dissipation sheet can also be regarded as the depth at which the winding portion is buried in the heat dissipation layer. If this depth (t1-t2) is equal to or greater than the radius (d / 2) of the round wire, the contact area between the winding part and the heat dissipation layer is sufficiently large, and the object to be installed from the winding part via the heat dissipation layer. The amount of heat released to the can be improved. In addition, since the contact area is large, the bonding between the winding portion and the heat dissipation layer is strengthened, and the formation of a gap between the two due to vibration or the like can be suppressed.

<7> As the choke coil of the embodiment in which the heat dissipation layer is a heat dissipation sheet, a form in which the Asker C hardness of the compressed portion of the heat dissipation sheet is 80 or less can be exemplified.

  When the Asker C hardness is 80 or less, the tight contact with the concavo-convex surface of the wound portion is sufficiently ensured during compression. The heat dissipation sheet tends to be hardened by being compressed. The Asker C hardness of the heat dissipation sheet before compression is preferably 40 or less. The reason will be described in Embodiment 1 described later.

<8> As the choke coil of the embodiment, a form in which the thickness of the electrical insulating layer is 0.1 mm or more and 0.5 mm or less can be exemplified.

  By setting the electrical insulating layer to be 0.1 mm or more and 0.5 mm or less, the electrical insulating layer can be provided with electrical insulation that is not excessive or insufficient.

<9> As the choke coil according to the embodiment, a cylinder that is interposed between the outer peripheral surface of the inner core and the inner peripheral surface of the winding portion and ensures electrical insulation between the inner core and the coil. A bobbin having a hook-like portion that is interposed between an inner peripheral surface of the outer core and an end surface of the winding portion and ensures electrical insulation between the outer core and the coil The form provided with can be mentioned.

  According to the said structure, the insulation between a coil, an inner core, and an outer core can be ensured more reliably, and the operation | movement of a choke coil can be stabilized.

<10> As an embodiment of the choke coil including the bobbin, the inner core may be formed by insert molding on the bobbin.

  According to the above configuration, the productivity of the choke coil can be improved. If the inner core is insert-molded into the bobbin, the effort of inserting the inner core into the cylindrical part of the bobbin and the effort of arranging the inner core at an appropriate position in the cylindrical part when producing the choke coil can be reduced. Because you can.

<11> As a choke coil according to an embodiment including the bobbin, the bobbin includes a positioning portion that determines a position of the bobbin relative to the outer core by engaging with an opening end surface on the other end side of the outer core. Can be mentioned.

  According to the above configuration, since the relative position between the outer core and the bobbin is determined with high accuracy, the relative position between the outer core and the inner core disposed inside the cylindrical portion of the bobbin is also determined with high accuracy.

Details of Embodiments of the Present Invention Hereinafter, embodiments of the choke coil of the present invention will be described with reference to the drawings. The same reference numerals in the figure indicate the same names. In addition, this invention is not necessarily limited to the structure shown by embodiment, and is shown by the claim, and intends that all the changes within the meaning and range equivalent to a claim are included.

<Embodiment 1>
≪Overall structure≫
The choke coil 1α according to the first embodiment will be described with reference to FIGS. 1 is a schematic perspective view of a choke coil 1α, FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1, FIG. 3 is a cross-sectional view taken along line III-III, and FIG. 5-7 is explanatory drawing which shows the procedure of the manufacturing method of a choke coil.

  The choke coil 1α shown in FIGS. 1 to 3 includes an outer core 2, an inner core 3 (see FIGS. 2 and 3), and a coil 4, similar to the choke coil disclosed in Patent Document 1, and is an installation target of a cooling base or the like. Used in a state of being placed on the object 9. The choke coil 1α of the present embodiment further includes a bobbin 5 that ensures insulation between the coil 4 and the cores 2 and 3. The main difference between the choke coil 1α of the present embodiment and the conventional one is that it includes an electrical insulating layer 6 that closes the opening portion of the opening end face 2D facing the installation target 9 in the outer core 2. Hereinafter, each component provided in the choke coil 1α will be described in detail.

≪Outer core≫
The outer core 2 is a cylindrical magnetic body having openings on one end side (lower side in the drawing) and the other end side (upper side in the drawing), and the inner space is a member formed in a rectangular parallelepiped shape. That is, the inner peripheral surface of the outer core 2 is composed of four planes arranged in a frame shape. The shape of the outer peripheral surface of the cylindrical magnetic body is not particularly limited with respect to such an inner peripheral surface, and may be, for example, a cylindrical shape or a rectangular parallelepiped shape like the inner peripheral surface. The outer core 2 of the present embodiment is a member formed in a rectangular parallelepiped shape, that is, a rectangular tube-like member, similarly to the inner peripheral surface.

  As shown in FIGS. 2 and 3, the opening end faces 2U and 2D having openings in the outer core 2 are formed flat. In the present embodiment, the choke coil 1α is placed on the installation target 9 so that the opening end surface 2D faces the installation target 9.

  As the outer core 2, a soft magnetic powder (aggregate of soft magnetic particles) represented by an iron group metal such as iron or an alloy thereof (for example, Fe-Si alloy, Fe-Si-Al alloy) is compressed. A molded green compact can be used. An insulating coating such as phosphate or silicone is formed on the surface of the soft magnetic particles, and the eddy current loss of the green compact can be reduced by the insulating coating. As the outer core 2, a composite material obtained by molding a resin containing soft magnetic powder with a molding die can be used.

≪Inner core≫
As shown in FIG. 2, the inner core 3 is a columnar magnetic body having one end surface 3L and the other end surface 3R, and the one end surface 3L and the other end surface 3R are respectively the inner peripheral surfaces of the outer core 2. It is a member arrange | positioned facing two opposing planes. The shape of the inner core 3 is not particularly limited, and may be a cylindrical shape, an elliptical column shape, or a prismatic shape. The inner core 3 of the present embodiment is a member in which the corners of the outer peripheral surface (the surface excluding the end surface) of the prism are rounded as shown in FIG. 5, which is an explanatory diagram of a choke coil manufacturing method described later. .

  As the inner core 3, similarly to the outer core 2, a green compact or a composite material can be used. The inner core 3 may be composed of a single columnar magnetic body as shown in the figure, but is a powder compact or composite core piece, and a plate-shaped gap material having a lower magnetic permeability than the core piece. And a stacked columnar body in which are alternately connected. A nonmagnetic material such as alumina can be used for the gap material. The magnetic characteristics (such as relative magnetic permeability and saturation magnetic flux density) of the inner core 3 may be different from the magnetic characteristics of the outer core 2 described above, thereby improving the performance of the choke coil 1α. There are cases where it is possible.

≪Coil≫
The coil 4 includes a winding part 40 formed by winding a winding. The winding part 40 of this embodiment is formed by winding a winding in multiple layers, and has a rectangular tube shape along the outer shape of a cylindrical part 50 of the bobbin 5 described later. The rectangular tube-shaped winding portion 40 is a winding portion having a shape in which the end face has a substantially square shape (including a square shape) with rounded corners (see particularly FIG. 3). Of course, the winding part 40 may be formed in a cylindrical shape. The cylindrical winding portion is a winding portion whose end face shape is a closed curved surface shape (an elliptical shape, a perfect circle shape, a race track shape, etc.).

  The winding wire constituting the coil 4 is constituted by a covered wire having an insulation coating made of an insulating material on the outer periphery of a conductor such as a flat wire or a round wire made of a conductive material such as copper, aluminum, magnesium, or an alloy thereof. be able to. In this embodiment, a coated round wire in which the outer circumference of a copper round wire is coated with enamel (typically polyamideimide) is used. In addition, a covered rectangular wire in which the outer periphery of a rectangular wire having a rectangular cross section is covered with enamel can be used. In that case, the winding part 40 can be formed by making the coated rectangular wire edgewise.

  Both end portions 4A and 4B of the coil 4 are extended from the winding portion 40 and connected to a terminal member (not shown). An external device such as a power source for supplying power is connected to the coil 4 through the terminal member. The direction in which the end portions 4A and 4B are pulled out is not particularly limited, but in the present embodiment, the end portions 4A and 4B are pulled out in the cylinder axis direction of the outer core 2 (the direction connecting the centers of the openings).

≪Bobbins≫
The bobbin 5 includes a tubular portion 50 and flanges 51A and 51B formed at both ends of the tubular portion 50 (see FIG. 2 and FIG. 5 together). The inner core 3 described above is housed inside the cylindrical portion 50, and the winding portion 40 of the coil 4 described above is disposed on the outer periphery of the cylindrical portion 50. In other words, the cylindrical portion 50 is interposed between the outer peripheral surface of the inner core 3 and the inner peripheral surface of the winding portion 40, and ensures electrical insulation between the inner core 3 and the coil 4. .

  Here, the arrangement of the inner core 3 in the cylindrical portion 50 may be performed by inserting the inner core 3 into the cylindrical portion 50 as shown in the present embodiment, or the inner core 3 may be inserted into the cylindrical portion 50. 3 may be integrated by insert molding. In the former case, the inner core 3 can be fixed to the cylindrical portion 50 with an adhesive or the like.

  On the other hand, the bowl-shaped portions 51A and 51B are interposed between the inner peripheral surface of the outer core 2 and the end surface of the winding portion 40, and ensure electrical insulation between the outer core 2 and the coil 4. Is. The flange portions 51 </ b> A and 51 </ b> B are connected to the cylindrical portion 50 in a flange shape so that the inner core 3 can be inserted into the cylindrical portion 50.

  Here, the internal space of the cylindrical portion 50 opens to one hook-shaped portion 51A (51B) and does not open to the other hook-shaped portion 51B (51A), that is, the other hook-shaped portion 51B (51A) is formed. It can also be set as the form which seals the other end of the cylindrical part 50. FIG. In that case, when the inner core 3 is inserted into the cylindrical portion 50 from the hole of the flange-shaped portion 51A (51B), the end surface of the inner core 3 is abutted against the flange-shaped portion 51B (51A). The position of the inner core 3 can be determined with high accuracy.

  The bobbin 5 of the present embodiment further includes positioning portions 52A and 52B that determine the position of the bobbin 5 with respect to the outer core 2, and fixing portions 53A and 53B that fix the bobbin 5 to a mounting plate 7 described later. The positioning portion 52A (52B) is formed at the upper end of the bowl-shaped portion 51A (51B) and extends outward of the tubular portion 50. That is, the hook-shaped part 51A (51B) and the positioning part 52A (52B) are connected in a substantially L shape. The positioning portions 52 </ b> A and 52 </ b> B engage with the open end surface 2 </ b> U at the upper end of the outer core 2, and the position of the cylindrical portion 50 of the bobbin 5 in the outer core 2, that is, the position of the inner core 3 in the outer core 2. To decide.

  On the other hand, fixed part 53A (53B) is comprised by the wall part connected to the outer side of positioning part 52A (52B), and the leg part connected to the lower end of a wall part. The wall portion is formed substantially parallel to the flange portion 51A (51B), the leg portion is formed substantially parallel to the opening end surface 2D of the outer core 2, and the overall shape of the fixing portion 53A (53B) is roughly It is L-shaped. A hole is formed in the wall portion at a position corresponding to the flange portion 51 </ b> A (51 </ b> B), so that the inner core 3 can be easily inserted into the tubular portion 50. A collar (see FIG. 2) is embedded in the leg, and a screw hole 5h (see FIG. 5) for a bolt 9B for screwing the choke coil 1α to the installation target 9 is formed by the collar. . The fixing portions 53A and 53B are bonded to the mounting plate 7, as will be described in detail in the description of the manufacturing method of the subsequent choke coil, and the bobbin 5 and the mounting plate 7 are integrated. As a result, the relative position between the bobbin 5 and the mounting plate 7, that is, the relative relationship between the inner core 3 disposed inside the cylindrical portion 50 of the bobbin 5 and the outer core 2 integrated with the mounting plate 7. The position can be determined with high accuracy.

  Examples of the constituent material of the bobbin 5 described above include a polyphenylene sulfide (PPS) resin, a polytetrafluoroethylene (PTFE) resin, a liquid crystal polymer (LCP), a polyamide (PA) resin such as nylon 6, nylon 66, and polybutylene terephthalate. Thermoplastic resins such as (PBT) resin and acrylonitrile / butadiene / styrene (ABS) resin can be used. In addition, thermosetting resins such as unsaturated polyester resins, epoxy resins, urethane resins, and silicone resins can be used. The thermal conductivity of the bobbin 5 may be improved by adding a ceramic filler to the resin. As the ceramic filler, for example, nonmagnetic powder such as alumina or silica can be used.

≪Electrical insulation layer≫
The electrical insulating layer 6 is made of a material having excellent electrical insulation, and is a layer that closes the opening in the opening end surface 2D of the outer core 2, and is electrically insulated between the winding portion 40 and the installation object 9. It is a layer for securing. The electrical insulating layer 6 of the present embodiment is formed in a size that covers the entire opening end surface 2D including the opening, and is attached to the opening end surface 2D of the outer core 2. As an index of electrical insulation, it has a breakdown voltage of 2.5 kV / 50 μm or more.

  Here, the electrical insulating layer 6 of this embodiment has adhesiveness that integrates the outer core 2 and a mounting plate 7 described later. Considering the function of integrating the mounting plate 7 and the outer core 2, it is preferable that the formation range of the electrical insulating layer 6 is equal to or greater than the opening end surface 2 </ b> D of the outer core 2. As already described, the formation range of the electrical insulating layer 6 of the present embodiment is substantially the same as the opening end surface 2D of the outer core 2, so that the entire opening end surface 2D of the outer core 2 is attached by the electrical insulating layer 6. Bonded to the plate 7.

  The thickness of the electrical insulating layer 6 is preferably 0.1 mm or more and 0.5 mm or less. With this thickness, the electrical insulation layer 6 can be provided with electrical insulation that is not excessive or insufficient. The thickness is more preferably 0.2 mm or more and 0.4 mm or less, and most preferably 0.25 mm or more and 0.35 mm or less.

  As a constituent material of the electrical insulating layer 6 that satisfies electrical insulation and the above adhesiveness, for example, silicone resin, polyimide resin, or the like can be used. The above-described nonmagnetic and electrically insulating ceramic filler may be contained in the electrical insulating layer 6 to improve the thermal conductivity of the electrical insulating layer 6. The electrical insulating layer 6 may be composed of a double-sided pressure-sensitive adhesive sheet. In that case, the electrical insulating layer 6 can be formed on the mounting plate 7 simply by sticking the double-sided pressure-sensitive adhesive sheet to the mounting plate 7. For example, in the case of a double-sided pressure-sensitive adhesive sheet in which adhesive layers are formed on both surfaces of a base material made of a material having excellent electrical insulation, in addition to the function of integrating the mounting plate 7 and the outer core 2, It can be set as the electrical insulation layer 6 with the function to ensure electrical insulation between the coils 4. Specifically, a double-sided pressure-sensitive adhesive sheet in which an adhesive layer is formed with a silicone resin on both sides of a polyimide base material can be used.

≪Others≫
[Heat dissipation layer]
As shown in FIGS. 2 and 3, the choke coil 1α of the present embodiment further contacts both the electrical insulating layer 6 and the winding part 40 between the electrical insulating layer 6 and the outer peripheral surface of the winding part 40. A heat dissipation layer 8 is provided. The heat radiation layer 8 functions as a heat radiation path for efficiently releasing the heat of the coil 4 to the mounting plate 7 side. Therefore, the heat dissipation layer 8 preferably has excellent thermal conductivity, specifically 0.2 W / m · K or more, and more preferably 1 W / m · K or more. / M · K or more is more preferable, and 3 W / m · K or more is most preferable.

  The heat dissipation layer 8 has a function of firmly integrating the mounting plate 7 on which the coil 4 including the winding part 40, the outer core 2, and the electrical insulating layer 6 are formed. As a result, the relative positions of the outer core 2 and the inner core 3 disposed inside the winding portion 40 can be determined with high accuracy. In order for the heat dissipation layer 8 to exhibit this function, it is preferable that the winding of the winding portion 40 is embedded in the heat dissipation layer 8.

  The heat radiation layer 8 is preferably formed of a heat radiation sheet having excellent thermal conductivity. This is because when the choke coil 1α is manufactured, the heat radiating layer 8 can be formed simply by sticking the heat radiating sheet on the electrical insulating layer 6. In that case, the size of the heat dissipation sheet is preferably smaller than the opening of the outer core 2 as shown in FIGS. This is because when the outer core 2 is attached to the attachment plate 7 as shown in the choke coil manufacturing method described later, the heat dissipation sheet does not get in the way.

  When the heat radiating layer 8 is formed of a heat radiating sheet, it is preferable that the heat radiating sheet is compressed between the electrical insulating layer 6 and the outer peripheral surface of the winding portion 40. By doing so, the contact area between the heat dissipation layer 8 and the winding part 40 can be increased, so that the heat dissipation efficiency by the heat dissipation layer 8 and the bonding strength between the heat dissipation layer 8 and the winding part 40 can be improved.

In compression of the heat radiation sheet, as shown in FIG. 4, the thickness of the uncompressed portion of the heat radiation sheet is t1, the thickness of the most compressed portion is t2, and the winding of the winding portion 40 (covered circle) When the diameter of the line is d, it is preferable to satisfy the following regulations.
・ T2 ≦ 7mm
・ T1-t2 ≦ 0.7 × t1
・ 0.5 × d ≦ t1-t2

  The t <b> 2 is the shortest distance between the winding part 40 and the electrical insulating layer 6. By setting the thickness t2 of the heat radiation layer 8 at the shortest distance to 7 mm or less, the heat radiation layer 8 does not become too thick, and heat is radiated from the wound portion 40 via the heat radiation layer 8 to the installation target 9. Can be carried out effectively.

  Moreover, said t1-t2 is the maximum compression amount of the thermal radiation layer of a thermal radiation sheet. If this t1-t2 is 0.7 * t1 or less, the characteristic of the heat-radiation sheet before compression will not be impaired.

  T1-t2 that is the compression amount of the heat radiation sheet can also be regarded as the depth at which the winding part 40 is buried in the heat radiation layer 8. If the depth (t1-t2) is equal to or greater than the radius (d / 2) of the round wire, the contact area between the winding part 40 and the heat dissipation layer 8 is sufficiently large, and the winding part 40 via the heat dissipation layer 8 is obtained. The amount of heat released from the installation object 9 to the installation object 9 can be improved. Moreover, since the said contact area is large, joining of the winding part 40 and the thermal radiation layer 8 becomes firm, and it can suppress that a clearance gap is formed between both 40 and 8 by vibration etc.

  Here, when the winding is a covered rectangular wire, t1-t2 is preferably equal to or larger than the angle R of the cross section of the covered rectangular wire. That is, it is preferable that the covered rectangular wire is embedded in the heat radiating layer 8 and the heat radiating layer 8 reaches the flat portion of the covered rectangular wire.

  As a constituent material of the heat dissipation layer 8, for example, a silicone resin, an acrylic resin, or the like can be used. The heat dissipation layer 8 may contain the above-described nonmagnetic and electrically insulating ceramic filler to improve the thermal conductivity of the heat dissipation layer 8.

[Mounting plate]
The choke coil 1α according to the present embodiment further includes a mounting plate 7 serving as a base when the choke coil 1α is fixed to the installation target 9. The mounting plate 7 is a member on which the outer core 2 is placed, and also serves as a tray when moving the choke coil 1α.

  The mounting plate 7 has at least the same size as the opening end surface 2D of the outer core 2 in order to exhibit the function as a pedestal. The mounting plate 7 is preferably larger than the opening end surface 2D in order to improve the handling property of the choke coil 1α. In this embodiment, the length of the mounting plate 7 in the axial direction of the inner core 3 is larger than that of the outer core 2. It is getting longer. On the other hand, the length of the mounting plate 7 in the direction orthogonal to the axial direction of the inner core 3 is substantially the same as that of the outer core 2. A screw hole 7h (FIG. 6) through which a bolt 9B for screwing the choke coil 1α to the installation object 9 is inserted is formed in a portion where the mounting plate 7 is elongated in the axial direction of the inner core 3. Yes.

  A characteristic required of the mounting plate 7 is that the mounting plate 7 is excellent in strength so that the mounting plate 7 is not bent or damaged by the weight of the outer core 2 or the like. Further, the mounting plate 7 preferably has excellent thermal conductivity, specifically, a thermal conductivity of 100 W / m · K or more, and the higher the thermal conductivity of the mounting plate 7, the higher the preferable one. By using the mounting plate 7 having high thermal conductivity, the heat generated when the choke coil 1α is used can be efficiently released to the installation object 9, and the operation of the choke coil 1α can be stabilized. Examples of the material of the mounting plate 7 satisfying the above characteristics include aluminum, aluminum alloy, magnesium, magnesium alloy, and the like.

≪Chalk coil manufacturing procedure≫
The choke coil 1α having the above-described configuration can be manufactured by a choke coil manufacturing method including the following steps α to γ.
[Step α] A first assembly C1 in which the inner core 3 and the coil 4 are integrated is produced. In the present embodiment, the first assembly C1 in which the bobbin 5 is integrated in addition to the inner core 3 and the coil 4 is produced.
[Step β] A second assembly C2 in which the outer core 2 and the mounting plate 7 are integrated is produced.
[Step γ] The first assembly C1 and the second assembly C2 are combined.
Hereafter, each process with which the manufacturing method of a choke coil is provided is demonstrated based on FIGS. Note that the order of the process α and the process β can be interchanged.

[Step α]
In performing the process α, the bobbin 5 is first prepared as shown in the upper diagram of FIG. Next, as shown in the lower diagram of FIG. 5, a winding portion 40 of the coil 4 is formed by winding a winding around the outer periphery of the cylindrical portion 50 of the bobbin 5, and an inner core is formed inside the cylindrical portion 50. 3 is inserted, and the 1st assembly C1 in which the inner core 3, the bobbin 5, and the coil 4 were united is produced. At that time, an adhesive is applied to the peripheral surface of the inner core 3 so that the position of the inner core 3 in the cylindrical portion 50 is fixed.

  Unlike the configuration described above, the bobbin 5 in which the inner core 3 is integrated by insert molding or the like may be manufactured, and the coil 4 may be formed in the integrated product. By doing so, the effort which inserts the inner core 3 in the cylindrical part 50 of the bobbin 5, and the effort of positioning of the inner core 3 in the cylindrical part 50 can be reduced.

[Step β]
In performing the process β, as shown in FIG. 6, first, the mounting plate 7 is prepared. Next, the electrical insulating layer 6 is formed on the upper surface of the mounting plate 7. If a double-sided PSA sheet is used as the electrical insulating layer 6, the electrical insulating layer 6 can be easily formed. Examples of the double-sided pressure-sensitive adhesive sheet include those in which an electrical insulating layer of a silicone resin is formed on both sides of a polyimide base material.

  Further, a heat dissipation sheet smaller than the opening of the outer core 2 is pasted on the electrical insulating layer 6 to form the heat dissipation layer 8. The heat radiating sheet is made of a silicone resin having excellent deformability. The Asker C hardness of the heat dissipation sheet is preferably 40 or less. A soft heat-dissipating sheet having an Asker C hardness of 40 or less is easily deformed when the winding portion 40 is pressed against the heat-dissipating sheet as will be described later.

  Finally, the outer core 2 is attached to the mounting plate 7 on which the electric insulating layer 6 is formed by aligning the outline of the electric insulating layer 6 and the outline of the opening end surface 2D of the outer core 2. As a result, a second assembly C2 in which the outer core 2 is integrated on the mounting plate 7 is formed.

[Process γ]
In step γ, as shown in FIG. 7, one end surface and the other end surface of the inner core 3 of the first assembly C1 are respectively opposed to two of the inner peripheral surfaces of the outer core 2 of the second assembly C2. The winding part 40 of the first assembly C1 is inserted into the outer core 2 so as to be opposed to the plane, and the first assembly C1 and the second assembly C2 are combined. In the present embodiment, the portion corresponding to the positioning portions 52A and 52B of the bobbin 5 on the opening end surface 2U on the upper side of the outer core 2 and the portion corresponding to the fixing portions 53A and 53B of the bobbin 5 on the mounting plate 7 are bonded in advance. The member 2b is formed. By forming the adhesive member 2b, the positioning portions 52A and 52B are fixed to the opening end surface 2U on the upper side of the outer core 2, and the fixing portions 53A and 53B are fixed to the mounting plate 7. Note that, when the two assemblies C1 and C2 are combined, the screw hole 5h of the bobbin 5 and the screw hole 7h of the mounting plate 7 are aligned.

  Here, when combining both assemblies C1 and C2, the winding portion 40 of the first assembly C1 is pressed against the heat dissipation layer 8 (heat dissipation sheet) of the second assembly C2. If the Asker C hardness of the heat dissipating sheet is 40 or less, the heat dissipating sheet is easily deformed. Therefore, even if the winding part 40 is pressed against the heat dissipating sheet, the winding part 40 is not damaged, and the lower end of the winding part 40 The side portion is embedded in the heat dissipation layer 8. Although the hardness of the compressed part in the heat radiation sheet is slightly higher than before compression, the Asker C hardness of the part is about 80 or less.

  Finally, the combination of the two assemblies C1 and C2 is heat-treated to cure the heat radiation layer 8 and the adhesive member 2b, thereby securely engaging the two assemblies C1 and C2 to complete the choke coil 1α. When the choke coil 1α is mounted on the installation target 9 as shown in FIG. 1, the choke coil 1α together with the mounting plate 7 may be disposed at a predetermined position on the installation target 9 and screwed with a bolt 9B.

≪Effect≫
In the choke coil 1α of the present embodiment described above, the opening of the opening end surface 2D of the outer core 2 is closed by the electrical insulating layer 6, as shown in FIGS. As a result, the creeping distance from the winding portion 40 of the coil 4 of the choke coil 1α to the mounting plate 7 becomes sufficiently long, so that the winding portion 40 and the installation object 9 on which the mounting plate 7 is placed There is sufficient electrical insulation between them. Therefore, the choke coil 1α of this embodiment is excellent in stability during operation.

  Further, the choke coil 1α of the present embodiment is provided with the mounting plate 7, and since all the constituent members of the choke coil 1α are integrally formed, it is easy to handle. Therefore, the installation of the choke coil 1α on the installation target 9 is easier than in the prior art, and the productivity of a product including the choke coil 1α can be improved.

<Embodiment 2>
In the second embodiment, a choke coil 1β in which the formation state of the electrical insulating layer 6 is different from that in the first embodiment will be described with reference to FIG.

  FIG. 8 is a longitudinal sectional view of the choke coil 1β of the second embodiment. In the choke coil 1β, the electrical insulating layer 6 has a size that covers the entire opening end surface 2D including the opening, and is in contact with the winding portion 40. That is, the choke coil 1β has a configuration in which the electrical insulating layer 6 and the heat dissipation layer 8 of the choke coil 1α of Embodiment 1 are integrated.

  In order to realize such a configuration, an insulating sheet may be formed on the mounting plate 7, and the insulating sheet may be compressed by the opening end surface 2 </ b> D of the outer core 2 and the winding portion 40. Here, if the insulating sheet is made of a material having excellent thermal conductivity, the electrical insulating layer 6 can also have a function as a heat dissipation layer.

  Also in the configuration of the second embodiment, the creeping distance from the winding portion 40 to the mounting plate 7 is sufficiently long due to the electrical insulating layer 6, so that the electrical connection between the winding portion 40 and the installation object 9 is electrically performed. Insulation can be ensured.

  The choke coil of the present invention can be used as a component part of a power conversion device such as a bidirectional DC-DC converter mounted on an electric vehicle such as a hybrid vehicle, an electric vehicle, or a fuel cell vehicle.

1α, 1β Choke coil C1 First assembly C2 Second assembly 2 Outer core 2D, 2U Open end surface 2b Adhesive member 3 Inner core 3L One end surface 3R Other end surface 4 Coil 40 Winding portion 4A, 4B End portion 5 Bobbin 50 Tube 51A, 51B Hook 52A, 52B Positioning 53A, 53B Fixing 5h Screw hole 6 Electrical insulation layer 7 Mounting plate 7h Screw hole 8 Heat radiation layer 9 Installation object 9B Bolt

Claims (11)

An outer core composed of a cylindrical magnetic body having an opening at one end and the other end, the inner space of which is formed in a rectangular parallelepiped shape,
An inner core composed of a columnar magnetic body, one end surface and the other end surface of which are arranged to face two opposing planes of the inner peripheral surface of the outer core;
A coil having a winding portion that is configured by winding a winding and disposed on the outer periphery of the inner core, and
A choke coil placed on an object to be installed in a state where the opening end face on one end side of the outer core faces.
A choke coil comprising an electrical insulating layer covering the entire opening at the opening end face on the one end side and extending to the opening end face.   2. The choke coil according to claim 1, wherein the electrical insulating layer is an insulating sheet disposed on the opening end face and having a size covering the entire opening end face in addition to the opening. Between the electrical insulating layer and the outer peripheral surface of the winding part, comprising a heat dissipation layer that contacts both the electrical insulating layer and the winding part,
The choke coil according to claim 1 or 2, wherein the heat dissipation layer has a thermal conductivity of 0.2 W / m · K or more.   4. The choke coil according to claim 3, wherein a distance between an outer end of the winding portion on the electric insulating layer side and the electric insulating layer is 7 mm or less. The heat dissipation layer is a heat dissipation sheet compressed between the electrical insulating layer and the outer peripheral surface of the winding part,
The thickness of the uncompressed portion of the heat radiating sheet is t1, and the thickness of the most compressed portion is t2, so that t1−t2 ≦ 0.7 × t1 is satisfied. The choke coil described in 1. The winding is a round wire;
The choke coil according to claim 5, wherein a diameter of a cross section of the round wire is d, and 0.5 × d ≦ t1−t2 is satisfied.   The choke coil according to claim 5 or 6, wherein an Asker C hardness of the compressed portion of the heat dissipation sheet is 80 or less.   The choke coil according to any one of claims 1 to 7, wherein a thickness of the electrical insulating layer is not less than 0.1 mm and not more than 0.5 mm. A cylindrical portion interposed between the outer peripheral surface of the inner core and the inner peripheral surface of the winding portion, and ensuring electrical insulation between the inner core and the coil;
A hook-shaped portion interposed between the inner peripheral surface of the outer core and the end surface of the winding portion to ensure electrical insulation between the outer core and the coil;
The choke coil according to any one of claims 1 to 8, further comprising a bobbin having   The choke coil according to claim 9, wherein the inner core is insert-molded in the bobbin.   11. The choke coil according to claim 9, wherein the bobbin includes a positioning portion that determines a position of the bobbin relative to the outer core by engaging with an opening end surface on the other end side of the outer core.

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