JP2017168489A - Heat radiation structure of coil component and coil component used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat radiation structure of coil component capable of satisfactory cooling both of core and wiring, and a coil component used therefor.SOLUTION: A heat radiation structure of a coil component 10 includes: a core 11 that forms a magnetic circuit and has a plurality of legs; and a wiring 12 which is wound on at least one leg selected from the legs. At least one face of the core 11 which has a generally flat part on the end face and at least a part of the generally flat part of the wiring 12 are in contact with a radiator S via a thermal conductivity material T.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a coil component such as a reactor, a transformer, and a choke coil used for a component of a power conversion device, and more particularly to a heat dissipation structure applied to these coil components.

  Conventionally, coil components such as a reactor, a transformer, and a choke coil are configured by a core material and a winding. Since these coil parts generate heat due to core loss and conduction loss of the winding, it is necessary to cool the core and the winding.

  As a method of cooling a reactor, a transformer, and the like, a method of cooling by bringing a core and a part of a winding into contact with a chassis has been proposed (see, for example, Patent Document 1).

  In addition, a method of cooling the winding by increasing the exposed area of the winding or flattening the winding has been proposed (see, for example, Patent Document 2).

JP 2012-039099 A Japanese Patent Laying-Open No. 2015-176886

  However, in the method described in Patent Document 1, the contact area of the winding is small, and the winding cannot be cooled sufficiently.

  Further, in the method described in Patent Document 2, since the contact area of the core is small, the core cannot be sufficiently cooled.

  In view of such problems of the prior art, an object of the present invention is to provide a heat dissipation structure for a coil component that can sufficiently cool both a core and a winding, and a coil component used therefor.

  To achieve the above object, a heat dissipation structure for a coil component according to the present invention forms a magnetic circuit, and is wound around a core having a plurality of legs and at least one wound leg selected from the legs, A heat dissipation structure for a coil component including a winding having a substantially flat portion on an end surface, wherein at least one surface of the core and at least a part of the substantially flat portion of the winding are interposed via a heat conductive material. It is characterized by being in contact with the radiator.

  Here, examples of the coil component include, but are not limited to, a reactor, a transformer, and a choke coil. Examples of the radiator include a metal casing (chassis), but are not limited thereto. Examples of the thermally conductive material include, but are not limited to, a thermally conductive resin. For example, when both ends of the winding have substantially flat portions, “at least part of the substantially flat portion” may be a substantially flat portion on one end surface, or each flat surface on both end surfaces. It may be a part. At least one of the both end faces of the winding may be in contact with the heat radiating body through the heat conductive material.

  Moreover, it is preferable that the said winding is wound around the said to-be-wrapped leg so that it may protrude to the outer side of the said core (as much as possible). It is preferable that the substantially flat portion of the winding and the radiator are arranged in parallel.

  According to the heat dissipation structure for the coil component having such a configuration, the heat generated from both the core and the winding is efficiently transmitted to the heat radiator such as the chassis, and the coil component can be sufficiently cooled.

  In the heat dissipation structure for a coil component according to the present invention, the coil component may further include a spacer that covers the wound leg, and the winding may be wound around the spacer. The spacer may have a rectangular or rounded rectangular cross section.

  According to the heat dissipation structure for a coil component having such a configuration, the area of the portion where the end face of the winding protrudes to the outside of the core can be enlarged, and the winding can be cooled more sufficiently.

  In the heat dissipation structure for a coil component according to the present invention, the wound leg may be an outer leg or a middle leg of the core.

  Of the heat dissipation structure of the coil component having such a configuration, particularly when the outer leg of the core is the wound leg, most of each end face of the winding protrudes to the outside of the core. An area can be secured and the winding can be sufficiently cooled.

  In the heat dissipation structure for a coil component according to the present invention, a plurality of the windings may be used, and at least one of them may be a three-layer insulated wire or a three-layer insulated litz wire.

  The heat dissipation structure of the coil component having such a configuration is particularly suitable for a transformer (transformer), not only can both the core and the winding be sufficiently cooled, but also the coupling capacity is reduced to reduce noise and the like. Loose coupling increases leakage inductance. Alternatively, the size can be reduced while maintaining the characteristics. Those using a three-layer insulated litz wire are particularly suitable for high frequency applications.

  Coil parts used in the heat dissipation structure for coil parts as described above are also within the scope of the present invention.

  According to the heat dissipation structure for a coil component of the present invention, heat generated from both the core and the winding is efficiently transmitted to a heat radiator such as a chassis, and the coil component can be sufficiently cooled.

  Further, the coil component of the present invention is suitable for such a heat dissipation structure.

(A) is sectional drawing which shows the basic concept of the thermal radiation structure of the reactor 10 which concerns on 1st Embodiment of this invention, (b) is a top view of the reactor 10. FIG. (A) And (b) is the other structural example of the thermal radiation structure of the reactor 10. FIG. (A) is a cross-sectional view of the core 11 used for the reactor 10, (b) is a cross-sectional view of the reactor 10A in which the cooling area of the winding 12 is relatively small, and (c) is a cooling of the winding 12. It is a cross-sectional view of the reactor 10B having a medium area, and (d) is a cross-sectional view of the reactor 10C in which the cooling area of the winding 12 is relatively large. (A) And (b) is a side view which illustrates the combination for implement | achieving the core 11. FIG. (A) is a cross-sectional view of the core 21 having a shape different from that of the core 11, and (b) is a cross-sectional view of the reactor 20 using the core 21. (A) And (b) is a side view which illustrates the combination for implement | achieving the core 21. FIG. (A) is sectional drawing which shows the thermal radiation structure of the transformer 30 which concerns on 2nd Embodiment of this invention, (b) is sectional drawing which shows the thermal radiation structure of the transformer 30A which is the modification. (A) is sectional drawing which shows the thermal radiation structure of the transformer 40 which concerns on 3rd Embodiment of this invention, (b) is sectional drawing which shows the thermal radiation structure of the transformer 40A which is the modification. (A) And (b) is sectional drawing which shows the Example for the effect confirmation by the thermal radiation structure of the reactor 10 which concerns on 1st Embodiment of this invention.

  Hereinafter, some embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
1.1 Basic Concept and Configuration Example FIG. 1A is a cross-sectional view showing the basic concept of the heat dissipation structure of the reactor 10 according to the first embodiment of the present invention, and FIG. 1B is a plan view of the reactor 10. It is. FIG. 2A and FIG. 2B are other configuration examples of the heat dissipation structure of the reactor 10.

  As shown in FIG. 1A, a rectangular parallelepiped core 11 forming a magnetic circuit and a winding 12 wound around the core 11 are formed below a plate-shaped metal chassis S extending in the horizontal direction. A reactor 10 having the same is mounted on the substrate B.

  The reactor 10 is an example of a coil component, and other examples include a transformer and a choke coil, but are not limited thereto.

  As shown in FIG. 1B, the winding 12 protrudes greatly to the outside of the core 11 and is wound so that both end faces 12a and 12b are substantially flat. In addition, the cross section of the electric wire (for example, enameled wire) used for the winding 12 is usually circular, and even if arranged in close contact so as to be macroscopically flat, it is microscopically completely flat. Therefore, the expression “substantially flat” is used here.

  At least one surface of the core 11 (specifically, the upper surface 11a) and at least a part of the substantially flat portion of the winding 12 (specifically, the upper end surface 12a) are arranged in parallel and are also thermally conductive. It is in contact with an upper chassis S that can be a cooler (heat radiator) through a thermally conductive resin T as an example of a thermal interface material (TIM). As a result, the upper surface 11a of the core 11 and the upper end surface 12a of the winding 12 are thermally connected to the chassis S via the thermal conductive resin T, so that the heat generated from both the core 11 and the winding 12 can be obtained. Is efficiently transmitted to the chassis S, and the reactor 10 can be sufficiently cooled.

  For example, as shown in FIG. 2 (a), when the chassis S exists below the reactor 10, the lower surface 11 b of the core 11 and the lower end surface 12 b of the winding 12 are placed downward via the heat conductive resin T. What is necessary is just to contact the chassis S. Note that the electrical connection between the reactor 10 and the substrate B can be made by an electric wire (not shown) or the like.

  As shown in FIG. 2B, when the chassis S exists above and below the reactor 10, the upper surface 11a of the core 11 and the upper end surface 12a of the winding 12 are connected via the heat conductive resin T. The lower surface 11b of the core 11 and the lower end surface 12b of the winding 12 may be brought into contact with the lower chassis S via the heat conductive resin T. Note that the electrical connection between the reactor 10 and the substrate B can be made by a lead wire (not shown) or the like, as in the case of FIG.

  According to such a configuration, the heat generated from both the core 11 and the winding 12 is efficiently transmitted to the upper and lower chassis S, respectively, so that the reactor 10 can be further sufficiently cooled.

  However, the destination for transferring the heat generated from the core 11 and the winding 12 is not necessarily limited to the upper and lower chassis S, and may be, for example, a heat sink or a heat sink.

1.2 Winding Shape, Winding Method, and Core Combination FIG. 3A is a cross-sectional view of the core 11 used in the reactor 10, and FIG. FIG. 3C is a cross-sectional view of a small reactor 10A, FIG. 3C is a cross-sectional view of a reactor 10B in which the cooling area of the winding 12 is medium, and FIG. It is a cross-sectional view of a large reactor 10C. FIG. 4A and FIG. 4B are side views illustrating combinations for realizing the core 11.

  As shown in FIG. 3A, the core 11 used in the reactor 10 has a rounded rectangular shape (two parallel lines of two equal lengths and two semicircular shapes, a shape often used in athletic fields) as shown in FIG. When the middle leg 11c is provided and the winding 12 is formed by directly winding an electric wire around the middle leg 11c, the end face of the winding 12 protrudes outside the core 11 as shown in FIG. The area of the portion, that is, the cooling area may be relatively small. Then, there is a possibility that the winding 12 cannot be sufficiently cooled.

  Therefore, for example, as shown in FIG. 3C, a rounded rectangular spacer 13B covering the outer side of the middle leg 11c of the core 11 with a certain thickness is fitted into the middle leg 11c, and an electric wire is wound around the spacer 13B. Thus, the winding 12 may be formed. Thereby, the area of the part which the end surface of the coil | winding 12 protrudes outside the core 11 can be expanded, and the coil | winding 12 can fully be cooled.

  Although the same effect can be obtained even if the middle leg 11c itself of the core 11 is made thicker, the material of the spacer 13B (for example, resin) is less expensive than the material of the core 11 (for example, ferrite). It is advantageous in terms of cost.

  For example, as shown in FIG. 3 (d), a spacer 13C that covers the outside of the middle leg 11c of the core 11 and has a horizontally long cross section is fitted into the middle leg 11c, and a wire is wound around the spacer 13C. 12 may be formed so that the overall outer shape is rectangular. Thereby, the area of the part where the end surface of the winding 12 protrudes to the outside of the core 11 can be similarly increased, and the winding 12 can be sufficiently cooled.

  The core 11 can be realized by, for example, an EE core 11A as shown in FIG. 4 (a) or an EI core 11B as shown in FIG. 4 (b). However, the shape of the outer legs and middle legs of the core 11 is not limited to these examples.

1.3 Modification of Reactor FIG. 5A is a cross-sectional view of a core 21 having a shape different from that of the core 11, and FIG. 5B is a cross-sectional view of a reactor 20 using the core 21. FIG. 6A and FIG. 6B are side views illustrating combinations for realizing the core 21.

  Unlike the reactor 10 described above, for example, by using a core 21 having no middle leg as shown in FIG. 5A, two outer legs 21a and 21b are respectively provided as shown in FIG. 5B. A reactor 20 in which the windings 22a and 22b are formed is also conceivable.

  In such a reactor 20, most of the end faces of the windings 22a and 22b protrude outside the core 21, so that a large cooling area can be secured and the windings 22a and 22b are sufficiently cooled. It becomes possible.

  The core 21 can be realized by, for example, a UU core 21A as shown in FIG. 6A or a UI core 21B as shown in FIG. 6B. However, the shape of the outer leg of the core 21 is not limited to these examples. Further, it can be realized using only the outer legs of the EE core 11A shown in FIG. 4A and the EI core 11B shown in FIG.

<Second embodiment and its modification>
FIG. 7A is a cross-sectional view showing a heat dissipation structure of a transformer 30 according to the second embodiment of the present invention, and FIG. 7B is a cross-sectional view showing a heat dissipation structure of a transformer 30A which is a modification thereof.

  As shown in FIG. 7A, a rectangular parallelepiped core 31 that forms a magnetic circuit is sandwiched between plate-shaped metal chassis S that extend horizontally in the upper and lower directions, and the core 31 is wound around the core 31. A transformer 30 having a primary winding 32 (upper side) and a secondary winding 33 (lower side) is arranged. The transformer 30 is also an example of a coil component.

  Normal wires are used for the primary winding 32 and the secondary winding 33, both of which protrude substantially outside the core 31 as in the case of the winding 12 of the first embodiment. Both are wound so as to be substantially flat.

  The upper surface of the core 31 and the upper end surface of the primary winding 32 are in contact with the upper chassis S via the heat conductive resin T, and the lower surface of the core 31 and the lower end surface of the secondary winding 33 are heated. The lower chassis S is in contact with the conductive resin T. Thereby, the heat generated from the core 31, the primary winding 32, and the secondary winding 33 is efficiently transmitted to the upper and lower chassis S, respectively, so that the transformer 30 can be sufficiently cooled.

  In addition, since the heat conductive resin T is also an insulating material, the core 31 and the chassis S are insulated. Further, the electrical connection between the substrate B mounted on the lower chassis S and the transformer 30 can be performed by an electric wire (not shown) or the like.

  In the transformer 30, the potential of the core 31 is set to a primary and secondary intermediate potential. For this reason, the distance d1 between the primary winding 32 and the upper chassis S and the distance d2 between the secondary winding 33 and the lower chassis S must each be a medium distance. Furthermore, it is necessary to ensure an appropriate insulation distance between the primary winding 32 and the secondary winding 33.

  On the other hand, as shown in FIG. 7B, in the transformer 30A in which the potential of the core 31 is the primary potential, a gap between the core 31 and the primary winding 32 is unnecessary, and thus the primary winding Since the distance d1 between the line 32 and the upper chassis S can be reduced, the heat conductive resin T can be reduced, and the heat dissipation of the upper part of the core 31 and the primary winding 32 is improved. However, since it is necessary to increase the distance d2 between the secondary winding 33 and the lower chassis S, the heat dissipation of the lower portion of the core 31 and the secondary winding 33 is lowered.

<Third embodiment and its modification>
FIG. 8A is a cross-sectional view showing a heat dissipation structure of a transformer 40 according to the third embodiment of the present invention, and FIG. 8B is a cross-sectional view showing a heat dissipation structure of a transformer 40A which is a modification thereof.

  Ordinary electric wires are used for the primary winding 32 and the secondary winding 33 of the second embodiment and its modification described above, but the primary windings 42 and 2 of the third embodiment and its modification. The secondary winding 43 is characterized in that a three-layer insulated wire is used for at least one side.

  In the transformer 40 shown in FIG. 8A, the potential of the core 31 is set to the primary potential, similarly to the transformer 30A of the modified example of the second embodiment shown in FIG. 7B. A normal electric wire may be used for the primary winding 42. When a three-layer insulated wire is used for the secondary winding 43, insulation is ensured by the secondary winding 43 itself, so that a gap between the core 31 and the secondary winding 43 becomes unnecessary. Since the distance d2 between the secondary winding 33 and the lower chassis S can also be reduced, the heat conductive resin T can be made thinner, and the heat dissipation of the lower portion of the core 31 and the secondary winding 43 is improved.

  Further, as can be seen from comparison with the transformer 30A shown in FIG. 7B, the interval between the primary winding 42 and the secondary winding 43 is increased. As a result, the coupling capacitance is reduced to reduce noise and the like, and loose coupling results in an increase in leakage inductance.

  On the other hand, as shown in FIG. 8B, the interval between the primary winding 42 and the secondary winding 43 is the same as that of the transformer 30A of the modification of the second embodiment shown in FIG. 7B. As a result, the transformer 40 can be reduced in size while maintaining the characteristics.

  Moreover, you may use the 3 layer insulation litz wire which replaced the center conductor of the 3 layer insulation wire with the litz wire. A litz wire is a twisted enameled wire that suppresses an increase in AC resistance due to the skin effect and proximity effect peculiar to high frequencies, and can prevent an increase in the temperature of the winding. Therefore, in the transformer 40 and the transformer 40A, the one using the three-layer insulated litz wire for at least one of the primary winding 42 and the secondary winding 43 is particularly suitable for high frequency applications.

  FIG. 9A and FIG. 9B are cross-sectional views showing examples for confirming the effect by the heat dissipation structure of the reactor 10 according to the first embodiment of the present invention.

  FIG. 9B shows the same configuration as that of the first embodiment, and the upper surface 11a of the core 11 and the upper end surface 12a of the winding 12 are in contact with the chassis S thereabove through the heat conductive resin T. The heat generated from both the core 11 and the winding 12 is efficiently transmitted to the chassis S.

  On the other hand, the configuration of FIG. 9A is different only in that the upper end surface 12a of the winding 12 is not in contact with the chassis S thereabove through the heat conductive resin T. The heat generated from the core 11 is efficiently transmitted to the chassis S, but the heat generated from the winding 12 is hardly transmitted to the chassis S.

  When each of these reactors 10 was operated under the same conditions, it rose to 120.1 ° C. in the configuration of FIG. 9A, whereas it increased to 111.5 ° C. in the configuration of FIG. 9B. Stayed. That is, the temperature rise could be suppressed by 8.6 ° C.

  Each configuration such as each embodiment described above and its modification may be combined with each other as long as there is no obstruction factor.

  It should be noted that the present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiments and examples are merely examples in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

10, 10A, 10B, 10C, 20 Reactor (coil parts)
11, 21, 31 Core 12, 22a, 22b Winding 13B, 13C Spacer 30, 30A, 40, 40A Transformer (coil parts)
32, 42 Primary winding 33, 43 Secondary winding B Substrate S Chassis (heat sink)
T Thermally conductive resin

Claims (11)

Forming a magnetic circuit and having a plurality of legs;
A heat dissipation structure for a coil component comprising a winding wound around at least one wound leg selected from the legs and having a substantially flat portion on an end surface,
A heat dissipation structure for a coil component, wherein at least one surface of the core and at least a part of the substantially flat portion of the winding are in contact with a heat sink via a heat conductive material. In the heat dissipation structure for a coil component according to claim 1,
A heat dissipation structure for a coil component, wherein the winding is wound around the wound leg so as to protrude outside the core. In the heat dissipation structure for a coil component according to claim 1 or 2,
The substantially flat part of the said coil | winding and the said heat radiator are arrange | positioned in parallel, The heat radiating structure of coil components characterized by the above-mentioned. In the heat dissipation structure of the coil component according to any one of claims 1 to 3,
A heat dissipation structure for a coil component, wherein at least one of both end faces of the winding is in contact with the heat dissipator through the heat conductive material. In the heat dissipation structure of the coil component according to any one of claims 1 to 4,
The coil component further includes a spacer that covers the wound leg,
The heat dissipation structure for a coil component, wherein the winding is wound around the outside of the spacer. In the heat dissipation structure for a coil component according to claim 5,
A heat dissipation structure for a coil component, wherein the spacer has a rectangular or rounded rectangular cross section. In the heat dissipation structure for a coil component according to any one of claims 1 to 6,
The heat-radiating structure for a coil component, wherein the wound leg is an outer leg or a middle leg of the core. In the heat dissipation structure for a coil component according to any one of claims 1 to 7,
A coil component heat dissipating structure characterized in that there are a plurality of windings and at least one of them is a three-layer insulated wire. In the heat dissipation structure for a coil component according to any one of claims 1 to 7,
A heat dissipation structure for a coil component, wherein there are a plurality of windings, and at least one of them is a three-layer insulated litz wire. In the heat dissipation structure for a coil component according to any one of claims 1 to 9,
The heat dissipating structure for a coil component, wherein the heat dissipating member is a metal casing.   The coil component used for the heat dissipation structure of the coil component of any one of Claims 1-10.

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