JP2013105854A - Reactor - Google Patents

Abstract

A reactor having improved heat dissipation is provided.
A reactor has a coil wound around a magnetic core. The coil 10 of the reactor 100 is covered with a resin 31 except for a part of the side surface (coil outer peripheral surface). Furthermore, the reactor 100 is provided with a metal heat radiating plate 33 that covers a portion of the coil 10 exposed from the resin. Between the coil 10 and the back surface of the heat radiating plate 33, a gel-like or curable heat transfer material 32 in contact with both is disposed. The heat transfer material 32 penetrates well between the coil windings, and the coil The heat of 10 is transmitted well to the heat sink 33.
[Selection] Figure 4

Description

  The present invention relates to a reactor (passive element using a coil). The reactor is also called “inductor”.

  In recent years, hybrid vehicles and electric vehicles have been put into practical use and are spreading. Since a hybrid vehicle or an electric vehicle uses a motor as a drive source, the electric circuit for the motor is often provided with a reactor. A reactor is used to smooth current in an inverter or a voltage converter. The main body of the reactor is obtained by winding a winding (coil) around a core. Ferrite is often used for the core.

  Some reactors have a bobbin around which a coil (winding) is wound, and some do not. Many reactors for smoothing a large current have a bobbin. A core is passed through a bobbin having flanges at both ends (or a resin bobbin is integrally molded around the core), and a coil (winding) is wound between the flanges of the bobbin. Also, for insulation, the entire coil is often covered with an insulator. It is advantageous in terms of cost to make the coil cover by resin casting. For example, Patent Document 1 discloses an example of such a reactor.

JP 2007-180140 A

  Since a large current flows through the reactor coil, the coil itself generates heat. If the entire coil is covered with resin, it is difficult for heat to diffuse. The technology disclosed in this specification provides a reactor with improved heat dissipation.

  The reactor disclosed in this specification is obtained by winding a coil around a magnetic core. In the reactor, the coil is covered with resin except for a part of the side surface (coil outer peripheral surface). Further, a metal heat radiating plate covering a portion of the reactor that is exposed from the resin of the coil is attached to the resin portion. A gel-like or curable heat transfer material in contact with both is disposed between the coil and the back surface of the heat sink. Here, “curability” means, for example, thermosetting or room temperature moisture absorption. Any of sclerosis | hardenability may be sufficient. That is, as the heat transfer material, a gel-like material or a material that is initially gel-like but hardens over time is used. A specific example of such a heat conductive material may be heat conductive silicon or silicon grease.

  The novel reactor which this specification discloses exposes a part of peripheral surface of a coil from resin, and applies a metal heat sink there. A curable heat transfer material is filled between the heat sink and the coil. Since the heat transfer material is at least initially in the form of a gel, it enters the gap between the coil windings. Therefore, heat efficiently moves from the coil to the metal plate. According to said technique, a reactor with good heat dissipation is obtained.

  In the reactor disclosed in the present specification, a metal heat sink is formed in a container shape by press drawing, and is attached to a resin member that covers the coil so that the coil fits in the container-shaped space. Preferably it is. Such a metal plate is easy to assemble.

  Further improvements of the present invention are described in the embodiments of the invention.

It is a disassembled perspective view of a reactor (primary molded product). It is a perspective view of a reactor (primary molded product). It is a perspective view of a reactor (secondary molded product). It is a side view of the reactor which attached the heat sink. It is a side view of the reactor in a modification. It is a side view of the reactor in another modification.

  A reactor according to an embodiment will be described with reference to the drawings. FIG. 1 shows an exploded perspective view of the reactor body 90 (without a resin cover), and FIG. 2 shows a perspective view of the reactor body 90 (without a resin cover). FIG. 3 shows an assembled perspective view of the reactor main body 90 and the heat radiating plate 33. 1 and 2 show a primary molded product before resin cover molding (before secondary molding). The reactor 100 is completed by assembling the heat transfer material 32 and the heat radiating plate 33 to the reactor main body 90 of the secondary molded product including the resin cover 31.

  The reactor 100 is used, for example, for current smoothing of an electric vehicle. The reactor 100 is for a large current having a current allowable value of, for example, 100 [A] or more, and a rectangular wire is used as a winding. A flat wire is a conducting wire having a rectangular cross section.

  Outline the reactor structure. In the reactor 100, a ring-shaped core is covered with a resin bobbin 2, and windings are wound around two portions of the bobbin 2 to form two coils 10a and 10b. The coils 10a and 10b are wound between the flanges 3 at both ends of the bobbin (FIG. 2). The coils 10a and 10b are covered with the resin cover 31 between the pair of flanges 3 (from one flange to the other flange) (FIG. 3). A coil lead wire 12 is drawn out from the resin cover 31. Moreover, an opening 31a is formed in a part of the resin cover 31, and a part of the peripheral surfaces of the coils 10a and 10b is exposed.

  Next, the reactor 100 will be described in detail. As shown in FIG. 1, the ring-shaped bobbin 2 is divided into two parts 2a and 2b at substantially the center in the longitudinal direction (X-axis direction). Accordingly, each of the components 2a and 2b has a C shape. Each component is provided with a rib 5 for attaching a heat radiating plate 33 described later.

  A C-shaped core 22a is embedded in the bobbin component 2a, and a C-shaped core 22b is embedded in the bobbin component 2b. The cores 22a and 22b are made of ferrite. When the bobbin parts 2a and 2b face each other, the cores 22a and 22b also face each other to form a ring-shaped core.

  A flange 3 is provided on each of the parts 2 a and 2 b of the bobbin 2. A conducting wire is wound between the flanges 3 at both ends of the bobbin 2 to form the coils 10a and 10b. The flange 3 is provided with a slit 4. As shown in FIG. 3, the lead wires 12 of the coils 10 a and 10 b pass through the slit 4 and extend to the outside of the flange 3 (outside in the coil axis direction).

  The reactor 100 will be further described in accordance with the manufacturing procedure. First, a bobbin 2 divided into two in the longitudinal direction is prepared (FIG. 1). The bobbin component 2a is formed by placing a C-shaped core 22a in a mold and injecting resin into a cavity around the core 22a. That is, the cored bobbin part 2a is made by resin injection molding. The same applies to the other bobbin part 2b.

  Next, as shown in FIG. 1, the bobbin parts 2a and 2b are fitted from the respective ends of the coils 10a and 10b. At this time, the lead wire 12 of the coil is passed through the slit 4 provided in the flange 3 of the bobbins 2a and 2b. The width of the slit 4 is substantially equal to the width of the lead wire 12, and the lead wire 12 fits snugly into the slit 4. Further, when the bobbin parts 2a and 2b are fitted to the coils 10a and 10b, the spacer 21 is disposed between the two bobbin parts 2a and 2b. The spacer 21 is made of a nonmagnetic material. The material of the spacer 21 is alumina ceramics, for example. Bobbins 2a and 2b are joined by an adhesive.

  When the bobbin parts 2a and 2b are fitted from both sides of the coils 10a and 10b, the reactor main body 90 (without the resin cover 31) shown in FIG. 2 is obtained. The reactor main body 90 before the resin cover 31 is molded may be referred to as a primary molded product. Next, the reactor main body 90 is put into another mold, and the resin is filled between the flanges 3 at both ends to form the resin cover 31 (FIG. 3). However, as described above, the resin cover 31 does not completely cover the coils 10a and 10b, but exposes part of the outer peripheral surface of the coils 10a and 10b. It should be noted that the reactor main body 90 of FIG. 3 is upside down with respect to FIGS. Although not visible in FIG. 3, the periphery of the slit 4 of the flange 3 is also covered with the resin cover 31. The lead wire 12 extends outward from the resin cover 31.

  Next, the heat sink 33 is attached so as to cover the exposed portions of the coils 10a and 10b (FIG. 3). The heat radiating plate 33 is formed by pressing an aluminum or copper metal plate into a container shape, and the exposed coils 10a and 10b are accommodated in the container portion. The heat radiating plate 33 is fixed to the rib 5 by bolts 34. A heat sink 33 including a heat transfer material 32 (described later) is attached to complete the reactor 100.

  A heat transfer material 32 is filled between the back surface of the heat radiating plate 33 and the side surfaces of the coils 10a and 10b. FIG. 4 shows a side view of the reactor 100. However, in FIG. 4, only the heat radiating plate 33 is shown in cross section so that the inside can be understood. In FIG. 4, the coils 10 a and 10 b are collectively referred to as a coil 10. As well shown in FIG. 4, the heat transfer material 32 is disposed so as to contact both the back surface of the heat radiating plate 33 and the side peripheral surface of the coil 10. The heat transfer material 32 is made of a thermosetting material containing silicon and is initially gel-like, but is cured when heated. The assembly procedure in the case of FIG. 4 is as follows. First, the reactor main body 90 is arranged with the exposed portion of the coil 10 facing up, the gel heat transfer material 32 is applied thereon, and the heat radiating plate 33 is attached. Finally, the entire reactor 100 is heated to cure the heat transfer material 32. In this case, since the heat radiation plate 33 can be assembled from above, workability is good, but it is necessary to select a material with low fluidity as the heat transfer material 32.

  The advantages of the reactor 100 described above will be described. In the reactor 100, most of the coil 10 is covered with a resin cover 31 and insulated from the outside. However, a part of the coil side surface is exposed from the resin cover 31 and is in contact with the metal heat radiating plate 33 through the heat transfer material 32. The heat transfer material 32 is at least initially in a gel form and penetrates well between the windings of the coil 10. The heat generated by the coil is transferred to the heat radiating plate 33 through the heat transfer material 32 and dissipated to the outside. Since the heat transfer material 32 penetrates well between the windings of the coil 10, the heat of the coil 10 is efficiently transferred to the heat radiating plate 33. That is, the reactor 100 has good heat dissipation efficiency.

  In FIG. 5, the side view of the reactor 200 of a modification is shown. In addition, the components which comprise a reactor are the same as the reactor 100 of FIGS. 1-4. In FIG. 5, the assembly procedure is different from that in FIG. In the case of FIG. 5, the reactor main body 90 is arranged with the exposed portion of the coil 10 facing down, and the heat radiating plate 33 in which the heat transfer material 232 is placed at the bottom of the container is assembled from below. Finally, the heat transfer material 242 is cured by heating. In this case, since the fluidity of the heat transfer material 232 may be high, the heat transfer material 232 penetrates well between the windings of the coil 10. In the reactor 200 of the modification, the heat transfer material 232 penetrates better between the coil windings than the reactor 100 of the embodiment, so that the heat dissipation efficiency is further improved.

  In FIG. 6, the side view of the reactor 300 of another modification is shown. In this modification, a metal flat plate is used for the heat radiating plate 333. Therefore, vertical ribs 55 are provided on both longitudinal sides of the coil 10 of the reactor main body 90, and the heat radiating plate 333 is fixed with bolts 34 on the top surface. The reactor 300 can be manufactured at a lower cost because a metal flat plate can be used.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this 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 exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

2: Bobbin 2a, 2b: Bobbin part 3: Flange 4: Slit 5: Rib 10, 10a, 10b: Coil 12: Lead wire 21: Spacer 22a, 22b: Core 31: Resin cover 32, 232: Heat transfer material 33, 333: Heat sink 34: Bolt 90: Reactor body 100, 200, 300: Reactor

Claims (2)

A reactor with a coil wound around a magnetic core,
The coil is covered with resin except for a part of the side surface,
A heat sink covering a portion exposed from the resin of the coil is attached to the resin portion,
Between the coil and the back surface of the heat sink, a gel-like or curable heat transfer material in contact with both is disposed,
A reactor characterized by that.   2. The heat radiating plate is made of metal and formed into a container shape by press drawing, and is attached to a resin covering the coil so that the coil is accommodated in the container-shaped space. The reactor described in.

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