WO2019044835A1

WO2019044835A1 - Heat-sink-mounted inductor

Info

Publication number: WO2019044835A1
Application number: PCT/JP2018/031773
Authority: WO
Inventors: 祥吾神戸
Original assignee: Ntn株式会社
Priority date: 2017-09-04
Filing date: 2018-08-28
Publication date: 2019-03-07
Also published as: JP2019046983A

Abstract

Provided is a heat-sink-mounted inductor that exhibits an excellent temperature-lowering effect by suppressing heat generation in a heat sink due to electromagnetic induction of magnetic flux leakage. This heat-sink-mounted inductor is provided with: a core (2); a coil (4) wound around the core (2); and a heat sink (5) which is made of a magnetic material and which is disposed directly or indirectly in contact with the coil (4) so as to release heat from the core (2) and the coil (4) to outside. The heat sink (5) has at least one opening that connects the coil side-facing surface thereof and the surface opposite thereto, and that reduces the heat generated by electromagnetic induction of the heat sink (5).

Description

Radiator with inductor

Related application

This application claims the priority of Japanese Patent Application No. 2017-169101 filed on Sep. 4, 2017, which is incorporated by reference in its entirety.

The present invention relates to an inductor with a heat sink used for large-sized electric equipment such as a power plant.

In the inductor, heat generation of the coil (copper loss) and heat generation of the core (iron loss) occur due to energization. In order to prevent the inductor from excessively rising in temperature due to such heat generation, it is necessary to attach a heat sink to enhance heat dissipation (for example, Patent Documents 1 and 2), or to force cooling by air cooling or water cooling. It is

JP, 2016-139699, A JP 2002-208521 A

When the inductor is energized, a leakage flux out of the magnetic circuit is generated separately from the main magnetic flux flowing through the magnetic circuit. When the heat sink is attached to the inductor, the leaked magnetic flux flows through the heat sink, causing the heat sink to generate electromagnetic induction to generate heat. As a result, the temperature reduction effect of the inductor due to the provision of the heat sink is reduced. In particular, in the case of an inductor used for a large-sized electrical installation such as a power plant, a gap is provided in the magnetic circuit, so that the leakage flux is large and the electromagnetic induction phenomenon of the heat sink becomes strong.

An object of the present invention is to provide an inductor with a heat sink which suppresses the heat generation of the heat sink due to the electromagnetic induction of the leakage flux and is excellent in the temperature lowering effect.

The inductor with a heat sink according to the present invention is a core, a coil wound around the core, and a heat sink which is in direct or indirect contact with the coil to release the heat of the core and the coil to the outside, A heat dissipation plate made of a magnetic material is provided, and the heat dissipation plate has at least one opening communicating with the surface facing the coil side and the opposite surface to reduce heat generation due to electromagnetic induction of the heat dissipation plate.

According to this configuration, since the heat sink has at least one opening, the amount of heat generation of the electromagnetic induction generated when the leakage magnetic flux which has deviated from the magnetic circuit of the core flows through the heat sink is reduced. For this reason, the heat radiation from the heat sink is favorably performed, and the temperature rise of the inductor can be suppressed.

The at least one opening may be a plurality of slits arranged parallel to one another. If at least one opening is a slit, machining of the at least one opening is easy.

A thermally conductive resin may be interposed between the coil and the heat sink. Thereby, the insulation of the inductor can be improved without impairing the heat conduction from the coil to the heat sink.

Any combination of the at least two configurations disclosed in the claims and / or the description and / or the drawings is included in the present invention. In particular, any combination of two or more of the claims is included in the present invention.

The invention will be more clearly understood from the following description of the preferred embodiments with reference to the accompanying drawings. However, the embodiments and the drawings are for the purpose of illustration and description only and are not to be taken as limiting the scope of the present invention. The scope of the invention is defined by the appended claims. In the accompanying drawings, the same reference numerals in multiple drawings indicate the same or corresponding parts.
It is the perspective view which broken the inductor with a heat sink concerning one embodiment of this invention by a longitudinal section. It is a top view of the inductor with a heat sink of FIG. It is an external appearance perspective view of the inductor main body of the inductor with a heat sink of FIG. It is the perspective view which broken the inductor main body of FIG. 3 by the longitudinal cross-section. It is a disassembled perspective view of the core of the inductor main body of FIG. It is a disassembled perspective view of the bobbin of the inductor main body of FIG. It is a perspective view of a part of 1st example of the heat sink of the inductor with a heat sink of FIG. It is a perspective view of a part of 2nd example of the heat sink of the inductor with a heat sink of FIG. It is a perspective view of the heat sink which shows the magnetic flux which flows through the heat sink which does not have an opening. It is a front view of the heat sink which shows the magnetic flux which flows through the heat sink of FIG. It is a side view of the heat sink which shows the magnetic flux which flows through the heat sink of FIG.

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of an inductor with a heat sink according to an embodiment of the present invention cut away in a longitudinal section, and FIG. 2 is a plan view of the inductor with a heat sink. This inductor with a heat sink is comprised of an inductor body 1 and a heat sink 5 for radiating the heat of the inductor body 1 to the outside. As shown in FIGS. 3 and 4 showing only the inductor body 1, the inductor body 1 has a core 2, a bobbin 3 and a coil 4. The coil 4 is wound around the core 2 via the bobbin 3.

As shown in FIG. 5, the core 2 of this embodiment is a UU-shaped core in which the respective tips of two

U-shaped core segments

2A and 2B are joined to each other. In the state where two

core divisions

2A and 2B are joined as shown in FIG. 1, a magnetic circuit L consisting of a closed circuit is formed. The bobbins 3 are assembled to the outer periphery of the central portion 2a of each of the core divided

bodies

2A and 2B, and the coil 4 is wound around each bobbin 3. The central portion 2a is cylindrical. The core 2 may have other shapes.

Each core divided

body

2A, 2B is a magnetic body formed of the same magnetic material. For example, sinterable pure iron or the like is applied as the magnetic substance. However, it is not limited to sinterable pure iron. As another magnetic material, a powder magnetic core material of amorphous type, pure iron type or the like can be used.

As shown in FIG. 6, the bobbin 3 is formed by joining two

bobbin split bodies

3A and 3B of the same shape to each other. The

divided bodies

3A and 3B are each incorporated in the core 2 as shown in FIGS. 3 and 4, and the cylindrical portion 3a fitted to the central portion 2a of the core 2 And 3b. The bobbin 3 is made of an insulating material. As the insulating material, for example, a resin material such as polyphenylene sulfide (PPS) is applied. The coil 4 may be directly wound around the core 2 without the bobbin 3.

The coil 4 is obtained by winding a conducting wire (not shown) around the outer periphery of the cylindrical portion 3a across the

flange portions

3b and 3b on both sides of the bobbin 3. The conducting wire is wound up to the outer diameter end of the flange 3b.

For example, a copper enameled wire is used as the wire of the coil 4. Specifically, urethane wire (UEW), formal wire (PVF), polyester wire (PEW), polyesterimide wire (EIW), polyamideimide wire (AIW), polyimide wire (PIW), a double-coated wire combining these, Or self fusion wire, litz wire, etc. can be used. A round wire or a square wire can be used as the cross-sectional shape of the copper enameled wire.

The heat sink 5 is made of a material having high thermal conductivity, such as a metal plate such as an iron plate. Therefore, the heat sink 5 is a magnetic body. As shown in FIG. 2, the heat sink 5 is disposed so as to surround the inductor body 1. In the case of the illustrated example, the heat sink 5 has a rectangular planar shape, and the upper and lower surfaces are open. Then, the coil 4 is in contact with a plurality of locations on the inner surface of the heat sink 5 via the heat conductive resin 6. The thermally conductive resin 6 is in surface contact with each of the coil 4 and the heat sink 5. The thermally conductive resin 6 is a resin having an insulating property and a high thermal conductivity. The heat conductive resin 6 has a certain thickness so that the insulation between the coil 4 and the heat sink 5 is not impaired.

The heat sink 5 may be in contact with only a part of the outer periphery of the coil 4 as shown in FIG. 2 or the heat sink 5 may be in contact with the entire outer periphery of the coil 4.

As the heat conductive resin 6, for example, a silicone resin such as silicone rubber, an acrylic resin, or the like is used. The resin formed into a tape or sheet is cut into an appropriate shape and size for use.

The heat dissipating plate 5 is provided with an opening for communicating the surface facing the coil side with the surface on the opposite side. This opening is provided to reduce the heat generation of the electromagnetic induction due to the leakage flux. The openings are, for example, a plurality of

slits

7 and 8 arranged in parallel with each other as shown in FIGS. 7 and 8, respectively. In the example of FIG. 7, the slits 7 are arranged in parallel to a plane perpendicular to the axis O of the coil. In the example of FIG. 8, the slits 8 are arranged in parallel with the axis O of the coil. In the example of FIGS. 7 and 8, the

slits

7 and 8 are provided substantially in the entire area of the surface 5 a that constitutes the long side of the rectangular shape of the heat sink 5. The openings may be circular or rectangular through holes other than the

slits

7 and 8.

The operation of this inductor with a heat sink will be described.

When the inductor body 1 is energized, heat is generated due to copper loss and iron loss. This heat is conducted to the heat sink 5 through the heat conductive resin 6 and is released from the heat sink 5 to the atmosphere. By interposing the thermally conductive resin 6 between the coil 4 and the heat dissipation plate 5, the insulation of the inductor main body 1 can be improved without impairing the heat conduction from the coil 4 to the heat dissipation plate 5.

By the way, at the time of electricity supply, when the leakage magnetic flux which deviated from the magnetic circuit L flows through the heat sink 5 which is a magnetic body, the heat sink 5 generates heat by electromagnetic induction. Specifically, in the case of the heat sink 5 having no opening, magnetic flux flows as shown in FIG. 9 to FIG. That is, the density of the magnetic flux is high at the portions A, B, C, and D adjacent to the coil 4, and the amount of heat generation is large.

However, in the heat sink 5 of the inductor according to the present embodiment, the amount of heat generation due to electromagnetic induction is reduced by providing the opening composed of the plurality of slits 7 (or 8) as shown in FIG. 7 or FIG. . For this reason, the heat radiation from the heat sink 5 is favorably performed, and the temperature rise of the inductor main body 1 can be suppressed.

Using the inductor body 1 shown in FIG. 3 as a model, the temperature reduction effect by the heat sink was confirmed by calculation. Table 1 shows the calorific value and temperature of each part when the inductor body of the model is energized under certain conditions. The description of the specifications of the inductor body, the detailed shape and dimensions of the heat sink, the calculation conditions, and the like will be omitted.

[About calorific value]
When the inductor body is energized, the copper loss of the coil is 226.9, the core loss of the core is 103.7, and the loss of the leakage flux is 123.2. The amount of heat generation of the heat sink when the heat sink without slits is attached to the inductor main body is 169.7. Similarly, the amount of heat generation of the heat sink when the heat sink having the horizontal slit (FIG. 7) is attached is 70.5, and the amount of heat generation of the heat sink when the heat sink having the vertical slit (FIG. 8) is attached Is 63.6. From these facts, it can be seen that the heat generation amount of the heat sink is significantly reduced when the slit is provided.

Further, it can be seen that the heat dissipation plate having the vertical slits has a smaller amount of heat generation than the heat dissipation plate having the horizontal slits. As the reason for this, it is considered that the heat dissipation plate having the vertical slits has a smaller cross-sectional area through which the leakage magnetic flux passes than the heat dissipation plate having the horizontal slits, so that the occurrence of the eddy loss is affected.

[About temperature]
While the temperature of the coil of the inductor main body to which the heat sink was not attached was about 140 °, when the heat sink was attached, the temperature of the coil was lowered to around 120 °. In particular, it can be seen that when the heat sink has a slit, the temperature of the coil is lower by about 3 to 4 ° as compared with the one without the slit. This is considered to be that the heat generation of the heat sink was suppressed by the slits, and as a result, the temperature of the coil was lowered. Moreover, when the heat sink having a lateral slit and the heat sink having a vertical slit are compared, the temperature is lower although the former has a larger amount of heat generation than the latter. As the reason, it is considered that the heat dissipating plate having the horizontal slits has a heat dissipating effect higher than the heat dissipating plate having the vertical slits, because the heat is easily transmitted to the corner portion (bent portion) which is a portion farther from the heat source.

As mentioned above, although the form for implementing this invention was demonstrated based on embodiment, embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is indicated not by the above description but by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

DESCRIPTION OF SYMBOLS 1 ... Inductor main body 2 ... Core 3 ... Bobbin 4 ... Coil 5 ... Heat sink 6 ... Thermally

conductive resin

7, 8 ... Slit (opening)

Claims

A core, a coil wound around the core, and a heat sink which directly or indirectly contacts the coil to release the heat of the core and the coil to the outside, the heat sink comprising a magnetic material; The inductor with a heat sink, wherein the heat sink is in communication with the surface facing the coil and the opposite surface to reduce heat generation due to electromagnetic induction of the heat sink.
The inductor with a heat sink according to claim 1, wherein the at least one opening is a plurality of slits aligned in parallel to one another.
The inductor with heat sink according to claim 1 or 2, wherein the thermally conductive resin intervenes between the coil and the heat sink.