JP2020053666A - Reactor and manufacturing method thereof - Google Patents

Reactor and manufacturing method thereof Download PDF

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JP2020053666A
JP2020053666A JP2019018163A JP2019018163A JP2020053666A JP 2020053666 A JP2020053666 A JP 2020053666A JP 2019018163 A JP2019018163 A JP 2019018163A JP 2019018163 A JP2019018163 A JP 2019018163A JP 2020053666 A JP2020053666 A JP 2020053666A
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coil
winding
flatness
insulating
heat dissipation
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JP7081519B2 (en
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和実 芹澤
Kazumi Serizawa
和実 芹澤
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Toyota Motor Corp
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Abstract

To provide a technique of enhancing an efficiency of heat transfer from a coil to an insulation heat dissipation layer.SOLUTION: A reactor 2 comprises: a winding 4 covered with an insulation film; and an insulation heat dissipation layer 12. The winding 4 forms a coil 5 having four flat side surfaces. The insulation heat dissipation layer 12 abuts on a lower surface of the coil. The insulation film of the winding 4 is removed at the lower surface contacting the insulation heat dissipation layer 12. Also, flatness of the lower surface of the coil is smaller than flatness of other side surfaces. It is difficult to achieve equally small flatness of all side surfaces of the coil 5, but it is possible to achieve small flatness of the lower surface abutting on the insulation heat dissipation layer 12 by allowing the flatness of other side surfaces to be large. The flatness of the lower surface abutting on the insulation heat dissipation layer 12 is small, so heat is uniformly transferred from the coil 5 to the insulation heat dissipation layer 12, which enhances heat transfer efficiency.SELECTED DRAWING: Figure 3

Description

本明細書が開示する技術は、リアクトルとその製造方法に関する。特に、コイルの平坦な側面に絶縁放熱層を挟んで冷却器が対向しているリアクトルと、その製造方法に関する。   The technology disclosed in this specification relates to a reactor and a method for manufacturing the reactor. In particular, the present invention relates to a reactor in which a cooler faces a flat side surface of a coil with an insulating heat radiation layer interposed therebetween, and a method for manufacturing the same.

角柱形状に巻回されたコイルの一つの側面に絶縁放熱層を挟んで冷却器が対向しているリアクトルが知られている(例えば、特許文献1)。絶縁放熱層は、コイルから冷却器への伝熱を補助するために採用されている。コイルを構成する巻線は、ピッチ方向で隣り合う巻線と短絡しないように絶縁膜で被覆されている。絶縁膜はコイルから絶縁放熱層への伝熱効率を下げるので、特許文献1のリアクトルでは、コイルの絶縁放熱層に対向している側面において絶縁膜が除去されている。絶縁放熱層は、コイル(巻線)から冷却器への伝熱を補助するとともに、コイルの露出した巻線と冷却器の間を絶縁する。なお、本明細書では、コイルの軸線に平行な面を「コイルの側面」と称する。   There is known a reactor in which a cooler is opposed to one side surface of a coil wound in a prismatic shape with an insulating heat radiation layer interposed therebetween (for example, Patent Document 1). The insulating heat dissipation layer is employed to assist heat transfer from the coil to the cooler. The winding constituting the coil is covered with an insulating film so as not to short-circuit with the winding adjacent in the pitch direction. Since the insulating film reduces the efficiency of heat transfer from the coil to the insulating heat dissipation layer, in the reactor of Patent Document 1, the insulating film is removed from the side of the coil facing the insulating heat dissipation layer. The insulating heat dissipation layer assists in transferring heat from the coil (winding) to the cooler and insulates between the exposed winding of the coil and the cooler. In this specification, a plane parallel to the axis of the coil is referred to as a “side surface of the coil”.

特開2016−92313号公報JP-A-2006-92313

絶縁放熱層が薄くなれば、コイルと冷却器の距離が短くなるので伝熱効率が高くなる。しかし、コイルの側面の平面度が大きいと(粗いと)、側面の各所と冷却器との間の距離がばらつく。すなわち、冷却器に最も近い巻線と最も遠い巻線との間の距離が大きくなる。冷却器に最も近い巻線と最も遠い巻線との間の距離が大きくなると、絶縁放熱層の厚みを大きくしなければならなくなる。絶縁放熱層が厚いほど熱抵抗が大きくなるので、絶縁放熱層の厚い箇所では伝熱効率が低化してしまう。さらには、絶縁放熱層の厚みが大きくなると、絶縁放熱層に亀裂が生じ易くなる。亀裂によって隙間(気泡)が生じると伝熱効率の低下を招く。一方、コイルの側面は、コイル軸線方向にならんだ巻線での集合体で形成されている。巻線のコイル半径方向の位置がずれると平面度が比較的に大きくなってしまう。特許文献1のリアクトルでは、冷却器に対向するコイル側面の平面度が考慮されておらず、改善の余地がある。   When the insulating heat radiation layer becomes thinner, the distance between the coil and the cooler becomes shorter, so that the heat transfer efficiency becomes higher. However, if the flatness of the side surface of the coil is large (rough), the distance between each part of the side surface and the cooler varies. That is, the distance between the winding closest to the cooler and the winding farthest increases. When the distance between the winding closest to the cooler and the winding farthest increases, the thickness of the insulating heat dissipation layer must be increased. Since the thermal resistance increases as the thickness of the insulating heat radiation layer increases, the heat transfer efficiency decreases at locations where the insulating heat radiation layer is thick. Furthermore, when the thickness of the insulating heat dissipation layer is increased, cracks are likely to occur in the insulating heat dissipation layer. When gaps (bubbles) are generated by cracks, the heat transfer efficiency is reduced. On the other hand, the side surface of the coil is formed of an aggregate of windings arranged in the coil axis direction. If the position of the winding in the coil radial direction shifts, the flatness becomes relatively large. In the reactor of Patent Document 1, the flatness of the side surface of the coil facing the cooler is not taken into consideration, and there is room for improvement.

なお、平面度は、例えば最大傾斜式平面度で評価すればよい。最大傾斜式平面度は、計測対象の平面を平行な2枚の理想平面で挟んだときの理想平面間の距離で表される。ここで、「理想平面」とは、数学の平面の方程式で表される、うねりの無い完全な平面を意味する。平面度が小さいほど、計測対象の平面は理想平面に近くなる。また、本明細書では、巻線の横断面の丸みは無視した平面度を評価する。   The flatness may be evaluated by, for example, a maximum inclination flatness. The maximum inclination flatness is represented by a distance between ideal planes when a plane to be measured is sandwiched between two parallel ideal planes. Here, the “ideal plane” means a perfect plane without undulations expressed by a mathematical plane equation. The smaller the flatness is, the closer the plane to be measured is to the ideal plane. In this specification, flatness is evaluated by ignoring roundness of the cross section of the winding.

巻線で形成されているコイルの全側面の平面度を小さくしようとすると、コイル全体を拘束することになり、コイルの各所に応力が発生する。応力は、スプリングバックとなって現れ、コイル側面における巻線の並びを乱してしまう。そこで、本明細書が開示するリアクトルでは、コイルの冷却器に対向していない側面では大きな平面度を許容することで応力の発生を抑え、冷却器に対向している側面の小さい平面度を維持する。   If it is attempted to reduce the flatness of all side surfaces of the coil formed by the winding, the entire coil is restrained, and stress is generated at various points of the coil. The stress appears as a springback and disturbs the arrangement of the windings on the side of the coil. Therefore, in the reactor disclosed in this specification, the generation of stress is suppressed by allowing a large flatness on the side of the coil not facing the cooler, and the small flatness of the side facing the cooler is maintained. I do.

本明細書が開示するリアクトルは、絶縁膜で被覆されている巻線が巻回されたコイルと、冷却器と、絶縁放熱層を備えている。コイルは、平坦な第1側面と、第1側面以外の第2側面を有している。第2側面は、第1側面の一方の縁から他方の縁へと続く1個の曲面であってもよいし、平坦な複数の側面を含むものであってもよい。後者の場合、コイルは多角柱形状となる。冷却器は、コイルの第1側面に対向している。絶縁放熱層は、第1側面と冷却器の間に挟まれている。第1側面において巻線の絶縁膜が除去されているとともに、第1側面の平面度が、第2側面の平面度よりも小さい。   The reactor disclosed in this specification includes a coil wound with a winding covered with an insulating film, a cooler, and an insulating heat dissipation layer. The coil has a flat first side surface and a second side surface other than the first side surface. The second side surface may be a single curved surface extending from one edge of the first side surface to the other edge, or may include a plurality of flat side surfaces. In the latter case, the coil has a polygonal prism shape. The cooler faces the first side of the coil. The insulating heat dissipation layer is sandwiched between the first side surface and the cooler. The insulating film of the winding is removed from the first side surface, and the flatness of the first side surface is smaller than the flatness of the second side surface.

本明細書が開示するリアクトルでは、冷却器に対向する第1側面以外の第2側面の平面度が大きくなることを許容することで、冷却器に対向する第1側面の小さくした平面度を維持することができる。冷却器に対向している第1側面の平面度を小さくすることで、絶縁放熱層の厚みのばらつきが小さくなる。その結果、第1側面の各所から冷却器へ均一に熱が伝わり、コイルから冷却器への伝熱効率が向上する。また、第1側面のコイル表面のばらつきが小さくなったことで、絶縁放熱層を薄肉化することができる。絶縁放熱層が薄肉化されることで、亀裂の発生も抑えられ、亀裂発生による伝熱効率低下が抑えられる。なお、以下では、絶縁膜が除去されている巻線の面を露出面と称する場合がある。   In the reactor disclosed in this specification, the flatness of the first side surface facing the cooler is maintained by allowing the flatness of the second side surface other than the first side surface facing the cooler to increase. can do. By reducing the flatness of the first side surface facing the cooler, variation in the thickness of the insulating heat dissipation layer is reduced. As a result, heat is uniformly transmitted from various portions of the first side surface to the cooler, and the efficiency of heat transfer from the coil to the cooler is improved. Further, since the variation of the coil surface on the first side surface is reduced, the thickness of the insulating heat dissipation layer can be reduced. By making the insulating heat dissipation layer thinner, the occurrence of cracks is suppressed, and the decrease in heat transfer efficiency due to the occurrence of cracks is suppressed. Hereinafter, the surface of the winding from which the insulating film has been removed may be referred to as an exposed surface.

コイルは、平角の巻線がエッジワイズに巻回されて構成されていることがある。そのような場合には、巻線は、絶縁放熱層に接している部分の断面形状(コイル軸線を含む平面でカットした断面形状)は、コイルの外側において隣接する巻線と隙間を有していてもよい。ピッチ方向で並んでいる巻線の露出面の間に隙間が確保される。露出面では導体が露出しているため、隣り合う露出面が近いと短絡を生じ得る。ピッチ方向で並んでいる露出面の間に隙間が確保されることで、ピッチ方向で隣り合う露出面の短絡を防ぐことができる。   The coil may be configured by winding a rectangular winding edgewise. In such a case, the cross-sectional shape of the portion of the winding that is in contact with the insulating heat dissipation layer (the cross-sectional shape cut by a plane including the coil axis) has a gap with the adjacent winding outside the coil. You may. A gap is secured between the exposed surfaces of the windings arranged in the pitch direction. Since the conductor is exposed on the exposed surface, a short circuit may occur if adjacent exposed surfaces are close. By securing a gap between the exposed surfaces arranged in the pitch direction, a short circuit between the exposed surfaces adjacent in the pitch direction can be prevented.

巻線の絶縁放熱層に接している部分のコイル内側での厚みがコイル外側での厚みよりも大きくなっていても、隣り合う露出面の間に隙間が確保され、露出面同士の短絡を防ぐことができる。また、コイルの軸線方向からみて第1側面に隣接するコイル角部における巻線のコイル内周側の厚みがコイル外周側の厚みよりも大きくなっていても、隣り合う露出面の間に隙間が確保され、露出面同士の短絡を防ぐことができる。   Even if the thickness of the part of the winding that is in contact with the insulating heat dissipation layer on the inside of the coil is larger than the thickness on the outside of the coil, a gap is secured between adjacent exposed surfaces to prevent short circuit between the exposed surfaces. be able to. Further, even if the thickness of the winding on the inner circumferential side of the coil at the coil corner adjacent to the first side surface when viewed from the axial direction of the coil is larger than the thickness on the outer circumferential side of the coil, a gap is formed between the adjacent exposed surfaces. As a result, a short circuit between the exposed surfaces can be prevented.

また、本明細書が開示するリアクトルでは、巻線の絶縁放熱層に接している部分においてピッチ方向で隣り合う巻線の間に絶縁物質が充填されていてもよい。巻線の露出面の近くで導電性の塵埃等が挟まれるとピッチ方向で隣り合う露出面が短絡してしまうおそれがある。隣り合う巻線の間に絶縁物質を充填することで、導電性の塵埃が挟まれることを防止することができる。   Further, in the reactor disclosed in this specification, an insulating material may be filled between adjacent windings in the pitch direction at a portion of the winding that is in contact with the insulating heat dissipation layer. If conductive dust or the like is sandwiched near the exposed surface of the winding, there is a possibility that adjacent exposed surfaces in the pitch direction may be short-circuited. By filling an insulating material between the adjacent windings, it is possible to prevent conductive dust from being caught.

本明細書が開示するリアクトルでは、絶縁放熱層はコイルの平側面に対して平行に位置しているセラミック板を含んでいてもよい。あるいは、絶縁放熱層は、シリコンとセラミック板で構成されていてもよい。隣り合う巻線の間、あるいは、絶縁放熱層内に小さな気泡(ミクロボイド)が存在すると、巻線と冷却器の間でコロナ放電が生じるおそれがある。コロナ放電は樹脂や絶縁膜の炭化を生じ、ピッチ方向で隣り合う露出面の短絡を誘発してしまうおそれがある。絶縁放熱層がセラミック板を含んでいることで、コロナ放電を防止することができる。また、セラミックの中には比較的に熱伝導率が高いものがある。そのようなセラミック板を採用することで、コイルから冷却器への伝熱効率を高める効果が得られる。   In the reactor disclosed in the present specification, the insulating heat dissipation layer may include a ceramic plate positioned parallel to the flat side surface of the coil. Alternatively, the insulating heat dissipation layer may be composed of silicon and a ceramic plate. If small bubbles (microvoids) exist between the adjacent windings or in the insulating heat dissipation layer, corona discharge may occur between the windings and the cooler. Corona discharge may cause carbonization of the resin and the insulating film, and may cause a short circuit between exposed surfaces adjacent in the pitch direction. Since the insulating heat dissipation layer includes the ceramic plate, corona discharge can be prevented. Some ceramics have relatively high thermal conductivity. By employing such a ceramic plate, an effect of increasing the efficiency of heat transfer from the coil to the cooler can be obtained.

本明細書が開示するリアクトルでは、巻線の露出面にスリットが設けられていてもよい。電流が流れるとコイルが発熱する。コイルが発熱すると巻線が膨張する。巻線が膨張すると、ピッチ方向で隣り合う露出面同士が近づき、短絡のおそれが生じる。巻線にスリットを設けることで、巻線の膨張を吸収し、短絡を防止することができる。   In the reactor disclosed in this specification, a slit may be provided on an exposed surface of the winding. When current flows, the coil generates heat. When the coil generates heat, the winding expands. When the winding expands, the exposed surfaces adjacent to each other in the pitch direction come closer to each other, which may cause a short circuit. By providing a slit in the winding, the expansion of the winding can be absorbed and a short circuit can be prevented.

本明細書は、上記したリアクトルの製造方法も提供する。その方法は、絶縁膜を除去する前の巻線を、平坦な側面(第1側面)を有するコイルとなるように巻回する巻回工程と、第1側面の平面度が第2側面よりも小さくなるように第1側面を研磨して絶縁膜を除去する研磨工程を含んでいる。巻線を巻回してからコイルの第1側面を研磨することで、絶縁膜を除去すると同時に平面度を小さくすることができる。   The present specification also provides a method for producing the above-described reactor. The method includes a winding step of winding a winding before removing an insulating film so as to form a coil having a flat side surface (a first side surface), and a flatness of the first side surface being higher than that of the second side surface. A polishing step of polishing the first side surface so as to reduce the size and removing the insulating film. By polishing the first side surface of the coil after winding the winding, the insulating film can be removed and the flatness can be reduced at the same time.

研磨に先立って、隣接する巻線の間に樹脂を充填するとよい。隣接する巻線の間の隙間に樹脂を充填することで、研磨かすが巻線間に詰まることが防止できる。   Prior to polishing, resin is preferably filled between adjacent windings. By filling the gap between the adjacent windings with resin, it is possible to prevent the polishing residue from being clogged between the windings.

本明細書が開示する技術の詳細とさらなる改良は以下の「発明を実施するための形態」にて説明する。   The details and further improvements of the technology disclosed in this specification will be described in the following “Detailed description of the invention”.

実施例のリアクトルの斜視図である。It is a perspective view of the reactor of an example. 実施例のリアクトルの斜視図である(コアと樹脂カバーなし)。It is a perspective view of a reactor of an example (without a core and a resin cover). 図1のIII−III線に沿った断面図である。FIG. 3 is a cross-sectional view along the line III-III in FIG. 1. 平面度を説明するためのコイル断面図である。It is a coil sectional view for explaining flatness. コイルの正面図である。It is a front view of a coil. 図3のVI−VI線に沿った断面図である。FIG. 6 is a sectional view taken along the line VI-VI of FIG. 3. 第1変形例のリアクトルのコイル断面図である。It is a coil sectional view of the reactor of the 1st modification. 第2変形例のリアクトルのコイル断面図である。It is a coil sectional view of the reactor of the 2nd modification. 第3変形例のリアクトルの断面図である。It is sectional drawing of the reactor of a 3rd modification. 第4変形例のリアクトルのコイル断面図である。It is a coil sectional view of the reactor of the 4th modification. 第5変形例のリアクトルのコイル断面図である。It is a coil sectional view of the reactor of the 5th modification. 第6変形例のリアクトルのコイル断面図である。It is a coil sectional view of the reactor of the 6th modification. 実施例のリアクトルの製造方法を説明する図である(1)。It is a figure explaining the manufacturing method of the reactor of an example (1). 実施例のリアクトルの製造方法を説明する図である(2)。It is a figure explaining the manufacturing method of the reactor of an example (2). 実施例のリアクトルの製造方法を説明する図である(3)。It is a figure explaining the manufacturing method of the reactor of an example (3).

図面を参照して実施例のリアクトル2を説明する。図1に、リアクトル2の斜視図を示す。リアクトル2は、コア20にコイル5が巻回された受動素子である。図1では、コア20とコイル5は樹脂カバー3で覆われており、見えない。リアクトル2は、例えば電気自動車に搭載されるチョッパ型の昇圧コンバータに用いられる。電気自動車の走行用モータは数十キロワットの出力が可能であり、リアクトル2のコイル5には数十キロワットの電力が流れる。大電力が流れるコイル5は発熱量が大きい。それゆえ、リアクトル2は、冷却器6を備えている。図2に、樹脂カバー3とコア20を除去したリアクトル2の斜視図を示す。また、図3に、図1のIII−III線に沿った断面図を示す。図2では、コア20は仮想線で描いてある。   The reactor 2 of the embodiment will be described with reference to the drawings. FIG. 1 shows a perspective view of the reactor 2. Reactor 2 is a passive element in which coil 5 is wound around core 20. In FIG. 1, the core 20 and the coil 5 are covered with the resin cover 3 and cannot be seen. Reactor 2 is used, for example, in a chopper type boost converter mounted on an electric vehicle. The traveling motor of the electric vehicle can output several tens of kilowatts, and several tens of kilowatts of electric power flows through the coil 5 of the reactor 2. The coil 5 through which a large amount of power flows generates a large amount of heat. Therefore, the reactor 2 includes the cooler 6. FIG. 2 shows a perspective view of the reactor 2 from which the resin cover 3 and the core 20 have been removed. FIG. 3 is a sectional view taken along the line III-III in FIG. In FIG. 2, the core 20 is drawn by a virtual line.

図2、図3を参照してリアクトル2の構造を説明する。コイル5は、巻線4を角柱形状に巻回して形成されている。コイル5は、平角の巻線4をエッジワイズに巻回したものである。エッジワイズとは、平角の幅広面をコイル軸線方向に向けて巻回する巻き方である。コイル軸線方向とは、コイル軸線の延伸方向であり、図中の座標系のX方向である。   The structure of the reactor 2 will be described with reference to FIGS. The coil 5 is formed by winding the winding 4 into a prismatic shape. The coil 5 is formed by winding a rectangular winding 4 in an edgewise manner. Edgewise is a winding method in which a flat wide surface is wound in the coil axis direction. The coil axis direction is the direction in which the coil axis extends, and is the X direction of the coordinate system in the drawing.

コイル5は四角柱形状を有しており、4個の平側面を有している。「コイル5の平側面」とは、コイル5の軸線Caに平行な平坦面を意味する。説明の便宜上、図中の座標系の+Z方向を向く平側面を上面5aと称し、−Z方向を向く平側面を下面5dと称する。また、+Y方向を向く平側面を右側面5bと称し、−Y方向を向く平側面を左側面5cと称する。   The coil 5 has a quadrangular prism shape, and has four flat side surfaces. The “flat side surface of the coil 5” means a flat surface parallel to the axis Ca of the coil 5. For convenience of explanation, the flat side surface facing the + Z direction of the coordinate system in the drawing is referred to as an upper surface 5a, and the flat side surface facing the -Z direction is referred to as a lower surface 5d. Further, the flat side surface facing the + Y direction is referred to as a right side surface 5b, and the flat side surface facing the −Y direction is referred to as a left side surface 5c.

冷却器6は、絶縁放熱層12を挟んでコイル5の下面5dと対向している。別言すれば、コイル5の下面5dが絶縁放熱層12を挟んで冷却器6に熱的に接している。また、コア20の下面が絶縁放熱層13を挟んで冷却器6に熱的に接している。冷却器6の下面には複数のフィン7が設けられている。図示は省略しているが、冷却器6の下面は冷媒流路に面しており、フィン7は液体冷媒に晒される。   The cooler 6 faces the lower surface 5d of the coil 5 with the insulating heat radiation layer 12 interposed therebetween. In other words, the lower surface 5d of the coil 5 is in thermal contact with the cooler 6 with the insulating heat radiation layer 12 interposed therebetween. The lower surface of the core 20 is in thermal contact with the cooler 6 with the insulating heat radiation layer 13 interposed therebetween. A plurality of fins 7 are provided on a lower surface of the cooler 6. Although not shown, the lower surface of the cooler 6 faces the refrigerant flow path, and the fins 7 are exposed to the liquid refrigerant.

絶縁放熱層12、13は、耐熱性と柔軟性を有するシリコンゴムで作られている。コイル5と冷却器6はともに金属製であるため、直接に接しても隙間が生じてしまう。そこで、コイル5と冷却器6の間に柔軟な絶縁放熱層12を挟み、コイル5から冷却器6への伝熱を補助する。絶縁放熱層13も同様の目的を有している。ただし、コイル5が発熱するので、コイル5の下面5dから冷却器6への伝熱効率がコイル5の冷却性能に特に影響する。それゆえ、コイル5から絶縁放熱層12への伝熱効率は高いことが望ましい。コイル5から絶縁放熱層12への伝熱効率を高める一つの方法は、コイル5の下面5dの平面度を小さくすることである。下面5dの平面度が大きいと、下面5dを絶縁放熱層12に押し付けたとき、下面5dと冷却器6の間のギャップのばらつきが大きくなる。ギャップのばらつきが大きいと、絶縁放熱層12の厚みが大きい箇所ができてしまう。絶縁放熱層12は厚いほど熱抵抗が大きくなるので、絶縁放熱層12の厚い箇所では伝熱効率が悪化してしまう。下面5dの平面度が小さいと、下面5dを絶縁放熱層12に押し付けたとき、下面5dと冷却器6の間のギャップのばらつきが小さくなる。ばらつきが小さいと、絶縁放熱層12の厚みも均一化し、下面5dの全体から絶縁放熱層12へ均一に熱が伝わり、伝熱効率が高まる。また、第1側面のコイル表面のばらつきが小さくなったことで、絶縁放熱層を薄肉化することができる。   The insulating heat radiation layers 12 and 13 are made of silicon rubber having heat resistance and flexibility. Since both the coil 5 and the cooler 6 are made of metal, there is a gap even when they are in direct contact. Therefore, a flexible insulating heat radiation layer 12 is interposed between the coil 5 and the cooler 6 to assist the heat transfer from the coil 5 to the cooler 6. The insulating heat radiation layer 13 has the same purpose. However, since the coil 5 generates heat, the heat transfer efficiency from the lower surface 5 d of the coil 5 to the cooler 6 particularly affects the cooling performance of the coil 5. Therefore, it is desirable that the heat transfer efficiency from the coil 5 to the insulating heat dissipation layer 12 be high. One method for increasing the efficiency of heat transfer from the coil 5 to the insulating heat radiation layer 12 is to reduce the flatness of the lower surface 5d of the coil 5. When the flatness of the lower surface 5d is large, when the lower surface 5d is pressed against the insulating heat dissipation layer 12, the variation in the gap between the lower surface 5d and the cooler 6 increases. If the variation in the gap is large, a portion where the thickness of the insulating heat dissipation layer 12 is large will be formed. Since the thermal resistance increases as the thickness of the insulating heat radiation layer 12 increases, the heat transfer efficiency deteriorates at a thick portion of the insulating heat radiation layer 12. When the flatness of the lower surface 5d is small, when the lower surface 5d is pressed against the insulating heat dissipation layer 12, the variation in the gap between the lower surface 5d and the cooler 6 is reduced. If the variation is small, the thickness of the insulating heat dissipation layer 12 is also made uniform, heat is uniformly transmitted from the entire lower surface 5d to the insulation heat dissipation layer 12, and the heat transfer efficiency is increased. Further, since the variation of the coil surface on the first side surface is reduced, the thickness of the insulating heat dissipation layer can be reduced.

平面度は、先に述べたように、最大傾斜式平面度で評価すればよい。図4を使ってコイル側面の平面度を具体的に説明する。図4は、コイル5の一部断面を模式的に示した図である。図の上側がコイル内側に相当し、下側はコイル外側に相当する。コイル5は、平角の巻線4をエッジワイズに巻回したものである。巻線4は、内部抵抗が小さく熱伝導率が高い銅で作られている。エッジワイズ巻では、平角の巻線4を強く折り曲げることになり、スプリングバックの発生などによりピッチごとの巻線の位置が揃い難い。図4に示すように、ピッチごとに巻線の半径方向の位置が異なることも起こり得る。図4において、平面S1(理想平面S1)は、最もコイル内側に位置する巻線4inにコイル外側で接する平面である。平面S2(理想平面S2)は、最もコイル外側に位置する巻線4outにコイル外側で接する平面である。平面S1と平面S2は平行である。コイル5の一側面を構成する全ての巻線のコイル外側の稜線は理想平面S1、S2の間に含まれる。そこで、最大傾斜式平面度の定義に従い、理想平面S1とS2の距離Rが、コイル側面の平面度を表すことになる。つまり、「コイル側面の平面度が小さい」とは、最もコイル内側に位置する巻線と、最もコイル外側に位置する巻線のそれぞれにコイル外側に接する平面の距離が小さいことを意味する。   The flatness may be evaluated by the maximum inclination type flatness as described above. The flatness of the side surface of the coil will be specifically described with reference to FIG. FIG. 4 is a diagram schematically showing a partial cross section of the coil 5. The upper side of the figure corresponds to the inside of the coil, and the lower side corresponds to the outside of the coil. The coil 5 is formed by winding a rectangular winding 4 in an edgewise manner. The winding 4 is made of copper having low internal resistance and high thermal conductivity. In the edgewise winding, the rectangular winding 4 is strongly bent, and it is difficult to align the winding positions for each pitch due to occurrence of springback or the like. As shown in FIG. 4, the position of the winding in the radial direction may differ for each pitch. In FIG. 4, a plane S1 (ideal plane S1) is a plane that is in contact with the winding 4in located on the innermost side of the coil on the outside of the coil. The plane S2 (ideal plane S2) is a plane that is in contact with the outermost winding 4out on the outside of the coil. The plane S1 and the plane S2 are parallel. Outer ridges of all windings constituting one side surface of the coil 5 are included between the ideal planes S1 and S2. Therefore, according to the definition of the maximum tilt flatness, the distance R between the ideal planes S1 and S2 represents the flatness of the coil side surface. In other words, “the flatness of the coil side surface is small” means that the distance between the windings located on the innermost side of the coil and the windings located on the outermost side of the coil is small.

図5に、コイル5の正面図を示す。図5では、コイル5の各側面の平面度を模式的に示してある。上面5aの平面度Raは、上面5aの最も窪んだ箇所に接する理想平面S1と、理想平面S1に平行であって上面5aの最も突出した箇所に接する理想平面S2の距離で表される。ピッチごとの巻線のコイル半径方向の位置がばらつくため、平面度Raは比較的に大きくなる。コイル5を作成した直後は、右側面5bの平面度Rb、左側面5cの平面度Rc、下面5dの平面度Rdも平面度Raとほぼ同じである。平角の巻線4は剛性が高いため、全ての側面の平面度を小さくするのには限界がある。すべての側面の平面度を小さくすると、コイル5の各所に高い応力が生じる。応力は、スプリングバックとなってあらわれ、いったん小さくした平面度を再び拡大させてしまうからである。   FIG. 5 shows a front view of the coil 5. FIG. 5 schematically shows the flatness of each side surface of the coil 5. The flatness Ra of the upper surface 5a is represented by a distance between an ideal plane S1 contacting the most depressed portion of the upper surface 5a and an ideal plane S2 parallel to the ideal plane S1 and contacting the most protruding portion of the upper surface 5a. Since the position of the winding in the coil radial direction at each pitch varies, the flatness Ra becomes relatively large. Immediately after the coil 5 is created, the flatness Rb of the right side surface 5b, the flatness Rc of the left side surface 5c, and the flatness Rd of the lower surface 5d are almost the same as the flatness Ra. Since the rectangular winding 4 has high rigidity, there is a limit in reducing the flatness of all side surfaces. If the flatness of all side surfaces is reduced, high stress is generated at various points of the coil 5. This is because the stress appears as a springback and causes the once reduced flatness to expand again.

そこで、実施例のリアクトル2のコイル5では、絶縁放熱層12に対向する下面5dの平面度Rdを小さくし、そのかわりに他の平側面(上面5a、右側面5b、左側面5c)については比較的に大きな平面度を許容する。別言すれば、絶縁放熱層12に接する下面5dの平面度Rdを、他の側面の平面度Ra、Rb、Rcよりも小さくする。その結果、コイル5に生じる応力が小さくなり、スプリングバックも小さくなる。したがって下面5dの小さい平面度を維持することが可能となり、下面5dから絶縁放熱層12への伝熱効率が高まる。   Therefore, in the coil 5 of the reactor 2 of the embodiment, the flatness Rd of the lower surface 5d facing the insulating heat dissipation layer 12 is reduced, and the other flat side surfaces (the upper surface 5a, the right side surface 5b, and the left side surface 5c) are replaced. Allows a relatively large flatness. In other words, the flatness Rd of the lower surface 5d in contact with the insulating heat dissipation layer 12 is made smaller than the flatnesses Ra, Rb, and Rc of the other side surfaces. As a result, the stress generated in the coil 5 decreases, and the springback also decreases. Therefore, the lower flatness of the lower surface 5d can be maintained, and the efficiency of heat transfer from the lower surface 5d to the insulating heat radiation layer 12 increases.

図6に、図3のVI−VI線に沿った断面図の一部を示す。図6の断面は、コイル5の軸線Ca(図3参照)を含む平面でコイル5をカットした断面に相当する。軸線Caは、図中の座標系のX軸に平行に延びている。図6は、コイル5の下面5dを構成する部位の部分断面図である。また、図6は、コイル5の軸線Caの方向の一部のみを示している。コイル5の巻線4は、隣のピッチの巻線4との短絡を防ぐため絶縁膜41で被覆されている。図6では、最も右側の巻線にのみ符号4(巻線4)と符号41(絶縁膜41)を付し、残りの巻線には符号は省略した。絶縁膜41は、典型的にはエナメル被膜である。   FIG. 6 shows a part of a cross-sectional view along the line VI-VI in FIG. The cross section in FIG. 6 corresponds to a cross section obtained by cutting the coil 5 on a plane including the axis Ca of the coil 5 (see FIG. 3). The axis Ca extends parallel to the X axis of the coordinate system in the figure. FIG. 6 is a partial cross-sectional view of a portion constituting the lower surface 5d of the coil 5. FIG. 6 shows only a part of the coil 5 in the direction of the axis Ca. The winding 4 of the coil 5 is covered with an insulating film 41 in order to prevent a short circuit with the winding 4 of the adjacent pitch. In FIG. 6, reference numeral 4 (winding 4) and reference numeral 41 (insulating film 41) are assigned only to the rightmost winding, and reference numerals are omitted for the remaining windings. The insulating film 41 is typically an enamel coating.

巻線4は銅などの熱伝導率が高い金属で作られており、絶縁膜41は銅などの金属よりも熱伝導率が高くない。実施例のリアクトル2では、コイル5から絶縁放熱層12への伝熱効率を高めるため、巻線4の絶縁放熱層12に接している部位の絶縁膜が除去されている。先に述べたように、絶縁膜が除去されている面を露出面4aと称する。巻線4の露出面4aの集合がコイル5の下面5dを構成する。別言すれば、巻線4の露出面4aは、コイル5の下面5dに対応する面である。図6では、一部の外側面にのみ符号4aを付してある。後述するように絶縁被膜は、研磨によって除去される。研磨により巻線4の一部も平坦化される。それゆえ、露出面4aは平坦となる。巻線4の下面5dに相当する面の絶縁膜41が除去されていることにより、銅の巻線4が直接に絶縁放熱層12に接する。それゆえ、巻線4(コイル5)から絶縁放熱層12への伝熱効率が高まる。   The winding 4 is made of a metal having a high thermal conductivity such as copper, and the insulating film 41 has a higher thermal conductivity than a metal such as copper. In the reactor 2 of the embodiment, in order to increase the heat transfer efficiency from the coil 5 to the insulating heat dissipation layer 12, the insulating film of the part of the winding 4 which is in contact with the insulating heat dissipation layer 12 is removed. As described above, the surface from which the insulating film has been removed is referred to as an exposed surface 4a. The set of the exposed surfaces 4a of the winding 4 constitutes the lower surface 5d of the coil 5. In other words, the exposed surface 4a of the winding 4 is a surface corresponding to the lower surface 5d of the coil 5. In FIG. 6, reference numeral 4a is given only to a part of the outer surface. As described below, the insulating coating is removed by polishing. A part of the winding 4 is also flattened by the polishing. Therefore, the exposed surface 4a becomes flat. Since the insulating film 41 on the surface corresponding to the lower surface 5 d of the winding 4 is removed, the copper winding 4 directly contacts the insulating heat dissipation layer 12. Therefore, the heat transfer efficiency from the winding 4 (coil 5) to the insulating heat dissipation layer 12 is increased.

実施例のリアクトル2では、次の2点の特徴が、コイル5から絶縁放熱層12への伝熱効率の向上に寄与している。(1)コイル5の絶縁放熱層12に接している下面5dの平面度Rdが小さい。(2)下面5dにて巻線4の絶縁膜41が除去されている。   In the reactor 2 of the embodiment, the following two features contribute to the improvement of the heat transfer efficiency from the coil 5 to the insulating heat radiation layer 12. (1) The flatness Rd of the lower surface 5d of the coil 5 that is in contact with the insulating heat dissipation layer 12 is small. (2) The insulating film 41 of the winding 4 is removed from the lower surface 5d.

なお、図6に示すように、ひとつの露出面4aとその隣のピッチの露出面4aは、ギャップGhで隔てられており、短絡しない。ギャップGhは、概ね、絶縁膜41の厚みの2倍よりもわずかに大きい。   As shown in FIG. 6, the exposed surface 4a and the exposed surface 4a at the next pitch are separated by the gap Gh and do not short-circuit. The gap Gh is generally slightly larger than twice the thickness of the insulating film 41.

(第1変形例)図7に、第1変形例のリアクトル2aのコイル断面図を示す。図7の断面は、図6の断面に対応する。すなわち、図7は、絶縁放熱層12に接している部分をコイルの軸線を含む平面でカットした巻線104の断面形状を示している。巻線104は、平角線であり、エッジワイズに巻回されている。   (First Modification) FIG. 7 shows a coil sectional view of a reactor 2a according to a first modification. The cross section of FIG. 7 corresponds to the cross section of FIG. That is, FIG. 7 shows a cross-sectional shape of the winding 104 in which a portion in contact with the insulating heat radiation layer 12 is cut by a plane including the axis of the coil. The winding 104 is a rectangular wire and is wound edgewise.

コイル5を構成する巻線104は、絶縁放熱層12に接しているコイル5の下面5dにて絶縁膜41が除去されている。絶縁膜41が除去されている面を露出面104aと称する。また、巻線104は、絶縁放熱層12に接している部分をコイル5の軸線を含む平面でカットした断面形状が、コイル外側へ向けて先細りになっている。別言すれば、絶縁放熱層12に接している部分をコイルの軸線を含む平面でカットした断面形状が、コイル5の外側において隣接する巻線と隙間を有している。巻線104の断面がコイル外側へ向けて先細りになっていることで、ピッチ方向で隣り合う露出面104aの間の距離(ギャップGh)が実施例の場合と比較して長くなる。ギャップGhが長くなることで、隣り合う露出面104a同士の短絡がより確実に防げる。   The insulating film 41 is removed from the lower surface 5 d of the coil 5 which is in contact with the insulating heat dissipation layer 12 in the winding 104 constituting the coil 5. The surface from which the insulating film 41 has been removed is referred to as an exposed surface 104a. Further, the winding 104 has a cross-sectional shape obtained by cutting a portion in contact with the insulating heat radiation layer 12 with a plane including the axis of the coil 5 and is tapered toward the outside of the coil. In other words, a cross-sectional shape obtained by cutting a portion in contact with the insulating heat radiation layer 12 by a plane including the axis of the coil has a gap between the adjacent winding outside the coil 5. Since the cross section of the winding 104 is tapered toward the outside of the coil, the distance (gap Gh) between the exposed surfaces 104a adjacent in the pitch direction is longer than that in the embodiment. By increasing the gap Gh, a short circuit between the adjacent exposed surfaces 104a can be more reliably prevented.

絶縁放熱層12は、巻線4の露出した金属を冷却器6から絶縁する。図4に示されているように、コイル5の側面の平面度が大きいと、冷却器6に最も近い巻線4outと冷却器6から最も遠い巻線4inとの差が大きくなる。冷却器6に最も近い巻線4outと冷却器6から最も遠い巻線4inとの差が大きいと、総ての巻線に接するために絶縁放熱層12の厚みを大きくしなければならない。絶縁放熱層12の厚みが大きいと、伝熱効率が下がるのみならず、絶縁放熱層12の内部に亀裂が発生し易くなる。亀裂が発生すると亀裂に空気が入り込み伝熱効率をさらに低下させる。絶縁放熱層12は、コイル5と冷却器6の間で加圧した状態に保持される。それゆえ、長期にわたって使われると、経時劣化により絶縁放熱層12に亀裂が生じ得る。コイル5は、発熱による温度上昇と、冷却による温度降下を繰り返す。この熱サイクルも、絶縁放熱層12の経時劣化を促進する。絶縁放熱層12の厚みが大きいほど、亀裂発生の可能性が高くなる。実施例のリアクトル2では、絶縁放熱層12を薄くすることができるので、亀裂発生の可能性を低くすることができる。   The insulating heat radiation layer 12 insulates the exposed metal of the winding 4 from the cooler 6. As shown in FIG. 4, when the flatness of the side surface of the coil 5 is large, the difference between the winding 4out closest to the cooler 6 and the winding 4in farthest from the cooler 6 increases. If the difference between the winding 4out closest to the cooler 6 and the winding 4in farthest from the cooler 6 is large, the thickness of the insulating heat radiation layer 12 must be increased in order to contact all the windings. When the thickness of the insulating heat dissipation layer 12 is large, not only the heat transfer efficiency decreases, but also cracks are easily generated inside the insulation heat dissipation layer 12. When a crack occurs, air enters the crack and further reduces the heat transfer efficiency. The insulating heat dissipation layer 12 is maintained in a pressurized state between the coil 5 and the cooler 6. Therefore, when used for a long time, cracks may occur in the insulating heat dissipation layer 12 due to deterioration over time. The coil 5 repeats a temperature rise due to heat generation and a temperature drop due to cooling. This thermal cycle also promotes the deterioration of the insulating heat radiation layer 12 over time. The larger the thickness of the insulating heat dissipation layer 12, the higher the possibility of crack generation. In the reactor 2 of the embodiment, the insulating heat dissipation layer 12 can be made thin, so that the possibility of crack generation can be reduced.

(第2変形例)図8に、第2変形例のリアクトル2bのコイル断面図を示す。図8の断面は、図6の断面に対応する。すなわち、図8は、絶縁放熱層12に接している部分をコイルの軸線を含む平面でカットした巻線204の断面形状を示している。巻線204は、平角線であり、エッジワイズに巻回されている。   (Second Modification) FIG. 8 shows a coil sectional view of a reactor 2b according to a second modification. The cross section of FIG. 8 corresponds to the cross section of FIG. That is, FIG. 8 shows a cross-sectional shape of the winding 204 in which a portion in contact with the insulating heat radiation layer 12 is cut by a plane including the axis of the coil. The winding 204 is a rectangular wire and is wound edgewise.

巻線204は、コイル内側での厚みWaがコイル外側での厚みWbよりも大きい。ここで、巻線204の厚みとは、コイル軸線方向(図中のX方向)における巻線204の導体部分の幅を意味する。第2変形例の場合、絶縁放熱層12に接しているコイル外側の部分では絶縁膜41の厚みが大きく、絶縁放熱層12に接しないコイル内側の部分では絶縁膜41の厚みが薄い。巻線204の幅と絶縁膜41の厚みを上記の通りコイル半径方向の位置に応じて変えることで、巻線204のひとつの露出面204aとピッチ方向で隣り合う露出面204aとの間に大きなギャップGhを確保することができる。大きなギャップGhは、隣り合う露出面104a同士の短絡をより確実に防ぐ。   The winding 204 has a thickness Wa on the inside of the coil larger than a thickness Wb on the outside of the coil. Here, the thickness of the winding 204 means the width of the conductor portion of the winding 204 in the coil axis direction (X direction in the drawing). In the case of the second modification, the thickness of the insulating film 41 is large at the portion outside the coil that is in contact with the insulating heat radiation layer 12, and is small at the portion inside the coil that is not in contact with the insulating heat radiation layer 12. By changing the width of the winding 204 and the thickness of the insulating film 41 in accordance with the position in the radial direction of the coil as described above, a large gap is formed between one exposed surface 204a of the winding 204 and the adjacent exposed surface 204a in the pitch direction. The gap Gh can be secured. The large gap Gh more reliably prevents a short circuit between the adjacent exposed surfaces 104a.

(第3変形例)図9に、第3変形例のリアクトル2cの断面図を示す。図9の断面図は、図3の断面図に対応する。第3変形例のリアクトル2cの巻線304も、平角線であり、エッジワイズに巻回されている。巻線304は、コイル5の軸線Caの方向からみて、下面5dに隣接するコイル角部のコイル内周側の厚みがコイル外周側の厚みよりも大きくなっている。図9において破線Arが示す範囲(領域Ar)が、下面5dに隣接するコイル角部のコイル内周側の領域を示している。領域Arの厚みが大きいことでも、巻線304のコイル下面5dに相当する隣り合う露出面の間のギャップを大きくすることができる。ピッチ方向で隣り合う露出面の間のギャップを大きくすることで、それらの間の短絡をより確実に防ぐことができる。   (Third Modification) FIG. 9 is a sectional view of a reactor 2c according to a third modification. The sectional view of FIG. 9 corresponds to the sectional view of FIG. The winding 304 of the reactor 2c of the third modified example is also a rectangular wire and is wound edgewise. When viewed from the direction of the axis Ca of the coil 5, the winding 304 has a thickness on the inner peripheral side of the coil at a corner of the coil adjacent to the lower surface 5 d is larger than the outer peripheral side of the coil. In FIG. 9, a range (region Ar) indicated by a broken line Ar indicates a region on the inner circumferential side of the coil at the corner of the coil adjacent to the lower surface 5d. Even when the thickness of the region Ar is large, the gap between the adjacent exposed surfaces corresponding to the coil lower surface 5d of the winding 304 can be increased. By increasing the gap between the exposed surfaces adjacent in the pitch direction, a short circuit between them can be more reliably prevented.

コイル5は、平角の巻線304を四角柱状にエッジワイズに巻回したものである。平角の巻線304を四角柱状に巻回する場合、四角柱の角部の内側に治具を当てて巻線304を曲げる。巻線304を治具に強く押し当てつつ曲げることで、領域Arの部分を塑性変形させ、巻線304の導体部分の厚みを大きくできる。   The coil 5 is formed by winding a rectangular winding 304 into a square pole shape edgewise. When winding the rectangular winding 304 into a square pole shape, a jig is applied to the inside of the corner of the square pole to bend the winding 304. By bending the winding 304 while strongly pressing it against the jig, the portion of the region Ar is plastically deformed, and the thickness of the conductor portion of the winding 304 can be increased.

(第4変形例)図10に、第4変形例のリアクトル2dのコイル断面図を示す。図10の断面は、図6の断面に対応する。すなわち、図10は、絶縁放熱層12に接している部分をコイルの軸線を含む平面でカットした巻線404の断面形状を示している。   (Fourth Modification) FIG. 10 shows a coil sectional view of a reactor 2d according to a fourth modification. The cross section of FIG. 10 corresponds to the cross section of FIG. That is, FIG. 10 shows a cross-sectional shape of the winding 404 in which a portion in contact with the insulating heat radiation layer 12 is cut by a plane including the axis of the coil.

巻線404は、露出面404aにスリット405を備えている。スリット405は、コイル5の露出面404aから、コイル内側に向かって設けられる。スリット405は、コイル5のそれぞれの巻線404の延伸方向に沿って伸びている。スリット405は、熱膨張により巻線404が隣の巻線404に近づくことを防止する。露出面404aでは導体が露出している。スリット405は、隣り合う露出面404a同士の短絡防止に寄与する。なお、スリット405の形状に制限はない。例えば、巻線の延設方向に対して傾斜する複数の短いスリットが設けられてもよい。   The winding 404 has a slit 405 on the exposed surface 404a. The slit 405 is provided from the exposed surface 404a of the coil 5 toward the inside of the coil. The slit 405 extends along the direction in which each winding 404 of the coil 5 extends. The slit 405 prevents the winding 404 from approaching the adjacent winding 404 due to thermal expansion. The conductor is exposed on the exposed surface 404a. The slit 405 contributes to prevention of a short circuit between adjacent exposed surfaces 404a. The shape of the slit 405 is not limited. For example, a plurality of short slits inclined with respect to the direction in which the windings extend may be provided.

(第5変形例)図11に、第5変形例のリアクトル2eのコイル断面図を示す。図11の断面は、図6の断面をさらに拡大した断面に対応する。即ち、図11は、絶縁放熱層12に接している部分をコイルの軸線を含む平面でカットした巻線504の断面形状を示している。第5変形例のリアクトル2eでは、巻線504の絶縁放熱層12に接している部分においてピッチ方向(図中のX方向)で隣り合う巻線の間に絶縁物質506が充填されている。巻線504の露出面504aの近くで導電性の塵埃等が挟まれるとピッチ方向で隣り合う露出面504aが短絡してしまうおそれがある。隣り合う巻線504の間に絶縁物質506を充填することで、導電性の塵埃が挟まれることが防止できる。   (Fifth Modification) FIG. 11 is a sectional view of a coil of a reactor 2e according to a fifth modification. The cross section in FIG. 11 corresponds to a cross section obtained by further enlarging the cross section in FIG. That is, FIG. 11 shows a cross-sectional shape of the winding 504 in which a portion in contact with the insulating heat radiation layer 12 is cut by a plane including the axis of the coil. In the reactor 2e of the fifth modified example, the insulating material 506 is filled between the windings adjacent to each other in the pitch direction (X direction in the drawing) at the portion of the winding 504 in contact with the insulating heat dissipation layer 12. If conductive dust or the like is sandwiched near the exposed surface 504a of the winding 504, there is a possibility that the exposed surfaces 504a adjacent in the pitch direction may be short-circuited. By filling the insulating material 506 between the adjacent windings 504, it is possible to prevent conductive dust from being caught.

(第6変形例)図12に、第6変形例のリアクトル2fのコイル断面図を示す。図12の断面図は、図11の断面図に対応する。第6変形例のリアクトル2fでは、絶縁放熱層12が2層(絶縁性セラミック板121とシリコンシート122)で構成されている。絶縁性セラミック板121は、巻線504の露出面504aの側に配置されており、シリコンシート122は冷却器6の側に配置されている。絶縁性セラミック板121は、コイル5(巻線504の露出面504a)に接している。   (Sixth Modification) FIG. 12 is a sectional view of a coil of a reactor 2f according to a sixth modification. The sectional view of FIG. 12 corresponds to the sectional view of FIG. In the reactor 2f of the sixth modification, the insulating heat radiation layer 12 is composed of two layers (an insulating ceramic plate 121 and a silicon sheet 122). The insulating ceramic plate 121 is arranged on the side of the exposed surface 504a of the winding 504, and the silicon sheet 122 is arranged on the side of the cooler 6. The insulating ceramic plate 121 is in contact with the coil 5 (the exposed surface 504a of the winding 504).

冷却器6は導電性のアルミニウムで作られている。導電性の冷却器6とコイル5の間に小さな気泡(ミクロボイド)が存在すると、コロナ放電が生じるおそれがある。コロナ放電は樹脂や絶縁膜の炭化を生じる。炭化された樹脂や絶縁膜は導電性を有するようになるので、ピッチ方向で隣り合う露出面504aが短絡してしまうおそれがある。絶縁放熱層12がコイル5に接する絶縁性セラミック板121を含んでいることで、隣り合う露出面504aの近くで炭化が生じることがなく、信頼性が向上する。また、絶縁性セラミック板121には、熱伝導率の高いものが選ばれる。そのような絶縁性セラミック板121を採用することで、コイル5から冷却器6への伝熱効率を高める効果も期待できる。   The cooler 6 is made of conductive aluminum. If small bubbles (microvoids) exist between the conductive cooler 6 and the coil 5, corona discharge may occur. Corona discharge causes carbonization of the resin and the insulating film. Since the carbonized resin or insulating film becomes conductive, there is a possibility that the exposed surfaces 504a adjacent in the pitch direction may be short-circuited. Since the insulating heat dissipation layer 12 includes the insulating ceramic plate 121 in contact with the coil 5, carbonization does not occur near the adjacent exposed surface 504a, and the reliability is improved. Further, a material having high thermal conductivity is selected as the insulating ceramic plate 121. By employing such an insulating ceramic plate 121, an effect of increasing the heat transfer efficiency from the coil 5 to the cooler 6 can be expected.

図12では、絶縁性セラミック板121は、巻線504の露出面504aに直接に接している。絶縁性セラミック板121は、シリコンシート122の内部に埋設されてもよい。つまり、絶縁性セラミック板121は、露出面504aに接している必要はない。   In FIG. 12, the insulating ceramic plate 121 is in direct contact with the exposed surface 504a of the winding 504. The insulating ceramic plate 121 may be embedded inside the silicon sheet 122. That is, the insulating ceramic plate 121 does not need to be in contact with the exposed surface 504a.

(リアクトルの製造方法)次に、図13−図15を参照しつつリアクトルの製造方法を説明する。   (Method of Manufacturing Reactor) Next, a method of manufacturing the reactor will be described with reference to FIGS.

(巻回工程)まず、平角の巻線4を、4個の平側面(上面5a、下面5d、右側面5b、左側面5c)を有する角柱形状となるように巻回し、コイル5を作成する。平角の巻線4は、エッジワイズに巻回される。巻線4は全周が絶縁膜で被覆されている。絶縁膜の一部は後に除去される。即ち、巻回工程では、絶縁膜を除去する前の巻線4が、少なくとも1個の平側面を有するコイル5となるように巻回される。   (Winding step) First, the rectangular winding 4 is wound into a prism shape having four flat side surfaces (upper surface 5a, lower surface 5d, right side surface 5b, left side surface 5c), and the coil 5 is formed. . The rectangular winding 4 is wound edgewise. The winding 4 is entirely covered with an insulating film. Part of the insulating film is removed later. That is, in the winding step, the winding 4 before removing the insulating film is wound so as to be the coil 5 having at least one flat side surface.

完成したコイル5は、コア20に挿通される(図13)。コア20は、複数個の分割されており、中央の柱状のコアブロックにコイル5が挿通された後、他の部位のコアブロックが接合され、コア20が完成する。   The completed coil 5 is inserted into the core 20 (FIG. 13). The core 20 is divided into a plurality of parts. After the coil 5 is inserted into the central pillar-shaped core block, the core blocks in other parts are joined to complete the core 20.

(モールド工程)次に、コア20とコイル5を覆う樹脂カバー3をモールド成形にて製造する(図14)。このとき、コア20の下面とコイル5の下面5dは露出される。後に、コア20とコイル5の露出部分に絶縁放熱層12、13が取り付けられ、さらに冷却器6が取り付けられる。   (Molding Step) Next, the resin cover 3 covering the core 20 and the coil 5 is manufactured by molding (FIG. 14). At this time, the lower surface of the core 20 and the lower surface 5d of the coil 5 are exposed. Later, the insulating heat radiation layers 12 and 13 are attached to the exposed portions of the core 20 and the coil 5, and the cooler 6 is further attached.

(研磨工程)次に、コイル5の露出している下面5dに硬質の絶縁物質506を塗布する。絶縁物質506が硬化した後、下面5dを研磨する(図15)。絶縁物質506は、コイル5の下面5dにおいて、ピッチ方向で隣り合う巻線4の間に充填される。絶縁物質506は、巻線4を被覆している絶縁膜よりも硬質である。なお、絶縁物質506を塗布する工程は、前述した第5変形例に必要な工程であり、必ずしも必要な工程ではない。そして、下面5dの平面度が他の側面(上面5a、右側面5b、左側面5c)の平面度よりも小さくなるように、下面5dを研磨して絶縁膜を除去する。このとき、下面5d以外の側面(上面5a、右側面5b、左側面5c)は拘束せず、平面度が大きくなることを許容する。そうすることで、コイル5の各所に発生する応力を緩和する。   (Polishing Step) Next, a hard insulating material 506 is applied to the exposed lower surface 5d of the coil 5. After the insulating material 506 is cured, the lower surface 5d is polished (FIG. 15). The insulating material 506 is filled between the windings 4 adjacent in the pitch direction on the lower surface 5 d of the coil 5. The insulating material 506 is harder than the insulating film covering the winding 4. Note that the step of applying the insulating material 506 is a step necessary for the above-described fifth modification, and is not necessarily a step. Then, the lower surface 5d is polished to remove the insulating film so that the flatness of the lower surface 5d is smaller than the flatness of the other side surfaces (the upper surface 5a, the right side surface 5b, and the left side surface 5c). At this time, the side surfaces (the upper surface 5a, the right side surface 5b, and the left side surface 5c) other than the lower surface 5d are not restricted, and the flatness is allowed to be increased. By doing so, the stress generated in each part of the coil 5 is reduced.

絶縁物質506は、研磨かすが巻線の間に残らないように、巻線の間を埋めている。また、図15に示すように、絶縁物質506は、コイル5の下面5dに隣接する角部も覆っている。巻線4を被覆している絶縁膜41は、柔らかく、グラインダ30がコイル5から離れるときにグラインダ30の研磨面に粘着してしまうおそれがある。図15の太線矢印は、グラインダ30の移動方向を示している。図15において、下面5dを研磨したグラインダ30は、コイル5の右下の角部から離れていく。コイル5の下面5dに隣接する角部(特にグラインダ30が離れていく角部)を硬質の絶縁物質506で覆うことで、絶縁膜41がグラインダ30の研磨面に粘着してしまうことが防止できる。   Insulating material 506 fills the gap between the turns so that no polishing residue remains between the turns. In addition, as shown in FIG. 15, the insulating material 506 also covers the corners adjacent to the lower surface 5d of the coil 5. The insulating film 41 covering the winding 4 is soft and may stick to the polished surface of the grinder 30 when the grinder 30 separates from the coil 5. 15 indicate the moving direction of the grinder 30. In FIG. 15, the grinder 30 whose lower surface 5d is polished moves away from the lower right corner of the coil 5. By covering the corners adjacent to the lower surface 5d of the coil 5 (particularly the corners where the grinder 30 separates) with the hard insulating material 506, it is possible to prevent the insulating film 41 from sticking to the polished surface of the grinder 30. .

(組立工程)最後に、絶縁膜が除去されたコイル5の下面5dに絶縁放熱層12を貼着し、コア20の下面に絶縁放熱層13を貼着し、絶縁放熱層の反対側に冷却器6を取り付ける。なお、絶縁放熱層12、13は、初期状態では液状であり、コア20の下面とコイル5の下面5dに塗布される。液状の絶縁放熱層12、13が硬化する前に冷却器が取り付けられる。液状の絶縁放熱層12、13が硬化すると、絶縁放熱層12、13を介してコイル5の下面5d(及びコア20の下面)と冷却器6が密着する。即ち、絶縁放熱層12(13)は、コイル5(コア20)と冷却器6を密着させる接着剤の役割を担う。   (Assembling step) Finally, the insulating heat radiation layer 12 is adhered to the lower surface 5d of the coil 5 from which the insulating film has been removed, the insulating heat radiation layer 13 is adhered to the lower surface of the core 20, and the cooling is performed on the opposite side of the insulating heat radiation layer. The vessel 6 is attached. Note that the insulating heat radiation layers 12 and 13 are liquid in the initial state, and are applied to the lower surface of the core 20 and the lower surface 5 d of the coil 5. A cooler is attached before the liquid insulating heat dissipation layers 12, 13 are hardened. When the liquid insulating heat radiation layers 12 and 13 are cured, the lower surface 5d of the coil 5 (and the lower surface of the core 20) and the cooler 6 come into close contact with each other via the insulating heat radiation layers 12 and 13. That is, the insulating heat radiation layer 12 (13) plays a role of an adhesive for bringing the coil 5 (core 20) and the cooler 6 into close contact with each other.

実施例で説明した技術に関する留意点を述べる。実施例とその変形例では、四角柱状のコイルの下面5dが冷却器6に対向し、他の側面(上面5a、右側面5b、左側面5c)は冷却器6に対向しない。冷却器6に対向する下面5dが第1側面の一例であり、そのほかの側面(上面5a、右側面5b、左側面5c)が第2側面の一例である。   Points to keep in mind regarding the technology described in the embodiment will be described. In the embodiment and its modification, the lower surface 5d of the quadrangular prism-shaped coil faces the cooler 6, and the other side surfaces (the upper surface 5a, the right side surface 5b, and the left side surface 5c) do not face the cooler 6. The lower surface 5d facing the cooler 6 is an example of a first side surface, and the other side surfaces (upper surface 5a, right side surface 5b, left side surface 5c) are examples of a second side surface.

絶縁放熱層を介して冷却器と対向するコイルの平側面は2面以上であってもよい。それぞれの平側面に絶縁放熱層が貼りつけられる。冷却器に対向する複数の平側面が第1側面の一例であり、冷却器に対向しない側面が第2側面の一例である。その場合でも、複数の第1側面の平面度が、冷却器に対向しない第2側面の平面度よりも小さい。   The flat side surface of the coil facing the cooler via the insulating heat dissipation layer may be two or more. An insulating heat dissipation layer is attached to each flat side surface. The plurality of flat sides facing the cooler is an example of a first side, and the side not facing the cooler is an example of a second side. Even in that case, the flatness of the plurality of first side surfaces is smaller than the flatness of the second side surface not facing the cooler.

実施例のコイルは4個の平側面を有している。本明細書が開示するリアクトルは、2個以上の平側面を有していてもよいし、唯一の平側面を有するものであってもよい。例えば、リアクトルのコイルは一つの平側面と、平側面の両端に接続される一つの曲面を有していても良い。   The coil of the embodiment has four flat side surfaces. The reactor disclosed in the present specification may have two or more flat sides, or may have only one flat side. For example, the coil of the reactor may have one flat side surface and one curved surface connected to both ends of the flat side surface.

絶縁放熱層12には、伝熱効率向上のために金属フィラーを混在させることがある。金属フィラーはクラック(気泡)を生じさせ易くする。絶縁放熱層12を薄くすることができる実施例の技術は、金属フィラーが混在した絶縁放熱層12を備えるリアクトルに対して特に有効である。   A metal filler may be mixed in the insulating heat dissipation layer 12 to improve heat transfer efficiency. The metal filler tends to cause cracks (bubbles). The technology of the embodiment in which the insulating heat dissipation layer 12 can be thinned is particularly effective for a reactor including the insulating heat dissipation layer 12 in which the metal filler is mixed.

リアクトルの組み立て工程において絶縁放熱層12と冷却器6の間に空気を巻き込まないように、絶縁放熱層12は、丸められた状態から展開されつつ冷却器6に貼り付けられる。絶縁放熱層12の厚みが大きいと、曲げ剛性が高くなり、丸められたときに亀裂が生じ易くなる。実施例で説明した技術は、絶縁放熱層の厚みを薄くすることができ、絶縁放熱層を丸めるときにも亀裂が生じ難くなる。   In order to prevent air from being trapped between the insulating heat dissipation layer 12 and the cooler 6 in the reactor assembly process, the insulating heat dissipation layer 12 is attached to the cooler 6 while being developed from a rolled state. When the thickness of the insulating heat dissipation layer 12 is large, the bending rigidity is increased, and a crack is easily generated when the insulation heat dissipation layer 12 is rounded. According to the technology described in the embodiments, the thickness of the insulating heat dissipation layer can be reduced, and cracks are less likely to occur even when the insulating heat dissipation layer is rounded.

実施例で説明した製造方法では、研磨によって絶縁膜を除去すると同時にコイルの側面の平面度を向上させる。絶縁膜は、レーザ、あるいは、溶媒の塗布によっても除去することができる。しかしながら、レーザ、あるいは、溶媒の塗布では、コイル側面の平面度は必ずしも向上しない。   In the manufacturing method described in the embodiment, the flatness of the side surface of the coil is improved while the insulating film is removed by polishing. The insulating film can also be removed by laser or application of a solvent. However, the flatness of the side surface of the coil is not necessarily improved by applying a laser or a solvent.

以上、本発明の具体例を詳細に説明したが、これらは例示に過ぎず、特許請求の範囲を限定するものではない。特許請求の範囲に記載の技術には、以上に例示した具体例を様々に変形、変更したものが含まれる。本明細書または図面に説明した技術要素は、単独であるいは各種の組合せによって技術的有用性を発揮するものであり、出願時請求項記載の組合せに限定されるものではない。また、本明細書または図面に例示した技術は複数目的を同時に達成し得るものであり、そのうちの一つの目的を達成すること自体で技術的有用性を持つものである。   As described above, specific examples of the present invention have been described in detail, but these are merely examples, and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples illustrated above. The technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings can simultaneously achieve a plurality of objects, and has technical utility by achieving one of the objects.

2、2a−2f:リアクトル
3:樹脂カバー
4、104、204、304、504:巻線
4a、104a、204a、404a、504a:露出面
5:コイル
6:冷却器
7:フィン
12、13:絶縁放熱層
20:コア
30:グラインダ
41:絶縁膜
121:絶縁性セラミック板
122:シリコンシート
405:スリット
506:絶縁物質
2, 2a-2f: reactor 3: resin cover 4, 104, 204, 304, 504: winding 4a, 104a, 204a, 404a, 504a: exposed surface 5: coil 6: cooler 7: fins 12, 13: insulation Heat radiation layer 20: Core 30: Grinder 41: Insulating film 121: Insulating ceramic plate 122: Silicon sheet 405: Slit 506: Insulating material

Claims (10)

絶縁膜で被覆されている巻線が巻回されたコイルであって、平坦な第1側面と、前記第1側面以外の第2側面とを有しているコイルと、
前記第1側面に対向している冷却器と、
前記第1側面と前記冷却器の間に挟まれている絶縁放熱層と、
を備えており、
前記第1側面において前記巻線の前記絶縁膜が除去されているとともに、前記第1側面の平面度が、前記第2側面の平面度よりも小さい、
リアクトル。
A coil wound with a winding covered with an insulating film, the coil having a flat first side surface and a second side surface other than the first side surface;
A cooler facing the first side surface;
An insulating heat radiation layer sandwiched between the first side surface and the cooler;
With
The insulating film of the winding is removed on the first side surface, and the flatness of the first side surface is smaller than the flatness of the second side surface;
Reactor.
前記コイルは平角の前記巻線をエッジワイズに巻回したものであり、
前記巻線は、前記絶縁放熱層に接している部分を前記コイルの軸線を含む平面でカットした断面形状が、前記コイルの外側において隣接する前記巻線と隙間を有している、請求項1に記載のリアクトル。
The coil is obtained by winding the flat rectangular winding edgewise,
The cross section of the winding, which is obtained by cutting a portion in contact with the insulating heat radiation layer by a plane including an axis of the coil, has a gap with the adjacent winding outside the coil. The reactor described in the above.
前記コイルは平角の前記巻線をエッジワイズに巻回したものであり、
前記巻線は、前記絶縁放熱層に接している部分のコイル内側での厚みがコイル外側での厚みよりも大きい、請求項1に記載のリアクトル。
The coil is obtained by winding the flat rectangular winding edgewise,
2. The reactor according to claim 1, wherein a thickness of a portion of the winding that is in contact with the insulating heat radiation layer inside the coil is larger than a thickness outside the coil. 3.
前記コイルは平角の前記巻線をエッジワイズに巻回したものであり、
前記コイルの軸線方向からみて前記第1側面に隣接するコイル角部における前記巻線のコイル内周側の厚みがコイル外周側の厚みよりも大きい、請求項1に記載のリアクトル。
The coil is obtained by winding the flat rectangular winding edgewise,
2. The reactor according to claim 1, wherein a thickness of the winding at an inner peripheral side of the coil at a corner of the coil adjacent to the first side surface when viewed from an axial direction of the coil is larger than a thickness at an outer peripheral side of the coil.
前記巻線の前記絶縁放熱層に接している部分においてピッチ方向で隣り合う前記巻線の間に絶縁物質が充填されている、請求項1から4のいずれか1項に記載のリアクトル。   The reactor according to any one of claims 1 to 4, wherein an insulating material is filled between the adjacent windings in the pitch direction at a portion of the winding that is in contact with the insulating heat dissipation layer. 前記冷却器の前記絶縁放熱層と接している面が導電性を有しており、
前記絶縁放熱層はセラミック板を含んでいる、請求項1から5のいずれか1項に記載のリアクトル。
The surface of the cooler that is in contact with the insulating heat dissipation layer has conductivity,
The reactor according to any one of claims 1 to 5, wherein the insulating heat dissipation layer includes a ceramic plate.
前記巻線の前記絶縁膜が除去されている面にスリットが設けられている、請求項1から6のいずれか1項に記載のリアクトル。   The reactor according to any one of claims 1 to 6, wherein a slit is provided on a surface of the winding from which the insulating film is removed. 前記絶縁放熱層が、シリコンとセラミック板で構成されている、請求項1から7のいずれか1項に記載のリアクトル。   The reactor according to any one of claims 1 to 7, wherein the insulating heat radiation layer is made of silicon and a ceramic plate. 請求項1から8のいずれか1項に記載のリアクトルの製造方法であり、
前記絶縁膜を除去する前の前記巻線を、平坦な前記第1側面を有する前記コイルとなるように巻回する巻回工程と、
前記第1側面の平面度が前記第2側面よりも小さくなるように前記第1側面を研磨して前記絶縁膜を除去する研磨工程と、
を備えている、リアクトルの製造方法。
A method for producing a reactor according to any one of claims 1 to 8,
A winding step of winding the winding before removing the insulating film to form the coil having the flat first side surface;
A polishing step of polishing the first side surface to remove the insulating film so that the flatness of the first side surface is smaller than that of the second side surface;
A method for producing a reactor, comprising:
前記研磨工程に先立ってピッチ方向で隣接する前記巻線の間に絶縁物質を充填する工程を含んでいる、請求項9に記載の製造方法。   The method according to claim 9, further comprising a step of filling an insulating material between the adjacent windings in the pitch direction prior to the polishing step.
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