ELECTROMAGNETIC INDUCTION APPARATUS

Abstract

 In an electromagnetic induction apparatus, coil portions, each including a wiring pattern on a printed wiring board and a metal member having both end portions connected to the wiring pattern, are electrically connected to each other and arranged side by side to form a coil body. Therefore, for example, by mounting cooling means onto the printed wiring board, heat can be efficiently radiated from the coil body to enable reduction in thermal resistance.

Description

Technical Field

[0001] The present invention relates to an electromagnetic induction apparatus to be incorporated into, for example, a power converter.

Background Art

[0002] In a power converter including a DC/DC converter and a charger to be mounted in an electric vehicle and a hybrid vehicle, electromagnetic induction apparatus such as a transformer, a reactor, and a choke coil are mounted as passive components for voltage step-up operation and voltage step-down operation, and are used as energy storing and emitting devices, DC current smoothening devices, or the like.

[0003] For the electromagnetic induction apparatus described above, a structure that enables downsizing or effective radiation of heat generated during energization is extremely important.

[0004] As a transformer excellent to achieve downsizing, there is known a transformer including primary windings and secondary windings in a laminate structure, in which the secondary windings are separately wound at least at two positions in an axial direction of a bobbin surrounding a core through intermediation of an insulating member, to thereby realize downsizing (see, for example, Patent Literature 1).

[0005] Further, as a reactor excellent in heat radiating property, there is known a reactor including a reactor main body housed inside an aluminum case. The reactor main body is sealed with a filler resin having a thermal conductivity of from 0.7 [W/m/K] to 4.0 [W/m/K] so that heat generated from a coil can be efficiently radiated to the case and a cooler. Further, a bobbin-less structure is provided so that heat generated from a core can also be efficiently radiated (see, for example, Patent Literature 2).

Citation List

Patent Literature

[0006] 

[PTL 1] JP 2010-183751 A

[PTL 2] JP 2009-94328 A

Summary of Invention

Technical Problem

[0007] The transformer of Patent Literature 1 can increase the degree of coupling between the windings by winding the primary windings and the second windings in a laminated manner. The downsizing is enabled by winding the second windings separately at the two or more positions in the axial direction of the bobbin. However, the windings are wound in a multilayer structure. Therefore, for an inner winding in the vicinity of the core, there is a problem in that the heat radiating property degrades by an additional thermal resistance of an insulator that is present between the windings on an outer side of the inner winding.

[0008] Further, the reactor of Patent Literature 2 has a problem in that costs and size are inevitably increased when the reactor main body is housed inside the metal case that is filled with the heat radiating resin.

[0009] The present invention has been made to solve the problems described above, and has an object to provide an electromagnetic induction apparatus in small size at low costs, which enables efficient heat radiation from a coil body to reduce a thermal resistance.

Solution to Problem

[0010] According to one embodiment of the present invention, there is provided an electromagnetic induction apparatus, including:

a core forming a closed magnetic path;

a printed wiring board configured to support the core, the printed wiring board including a plurality of wiring patterns; and

a metal member provided around the core and having both end portions connected to the plurality of wiring patterns,

in which a plurality of coil portions including the plurality of wiring patterns and the metal member are electrically connected to each other and arranged side by side to form a coil body.

Advantageous Effects of Invention

[0011] According to the electromagnetic induction apparatus of the one embodiment of the present invention, the coil portions, each including the wiring pattern on the printed wiring board and the metal member having the both end portions connected to the wiring pattern, are electrically connected to each other and arranged side by side to form the coil body. Therefore, for example, by mounting cooling means onto the printed wiring board, heat can be efficiently radiated from the coil body to enable reduction of the thermal resistance.

[0012] Further, the metal members are connected to the wiring patterns of the printed wiring board so as to be separated away from each other, for each of the metal members. Therefore, a heat radiating property for each of the metal members is also high.

Brief Description of Drawings

[0013] 

FIG. 1 is a perspective view of a reactor according to a first embodiment of the present invention.

FIG. 2 is a top view for illustrating wiring patterns on a metal-based printed wiring board illustrated in FIG. 1.

FIG. 3 is a perspective view of a transformer according to a second embodiment of the present invention.

FIG. 4 is a top view of wiring patterns on a metal-based printed wiring board illustrated in FIG. 3.

FIG. 5A is a diagram for schematically illustrating an example of arrangement of primary winding portions and secondary winding portions of a transformer.

FIG. 5B is a diagram for schematically illustrating the arrangement of the primary winding portions and the secondary winding portions of a transformer according to a third embodiment of the present invention.

Description of Embodiments

[0014] Embodiments of the present invention are described below. In the drawings, the same or corresponding components and parts are denoted by the same reference symbols for description.

First Embodiment

[0015] FIG. 1 is a perspective view of a reactor according to a first embodiment of the present invention, and FIG. 2 is a top view for illustrating wiring patterns 8 on a metal-based printed wiring board 6 illustrated in FIG. 1. In FIG. 1, the illustration of a plurality of electronic components mounted on the metal-based printed wiring board 6 is omitted.

[0016] The reactor, which is an electromagnetic induction apparatus, includes a core 3 that is a shell-type PQ core including a first core portion 1 and a second core portion 2, a plurality of plate-like metal members 4 each having a C-like shape and arranged so as to surround a middle leg portion of the core 3, insulating members 5 configured to insulate the plate-like metal members 4 from each other and the plate-like metal members 4 and the core 3 from each other, and the metal-based printed wiring board 6 having an upper surface on which a plurality of the wiring patterns 8 are provided.

[0017] By placing and fixing the metal-based printed wiring board 6 onto a cooler (not shown), which is cooling means, the reactor is fixed to the cooler.

[0018] The plate-like metal members 4 are tough-pitch copper members having a prescribed electric resistance value.

[0019] The wiring patterns 8 on the metal-based printed wiring board 6 are conductors having a prescribed electric resistance value, and are coated with an insulating resist except for component lands 7 each having a rectangular shape or the like. The wiring patterns 8 are electrically connected to the plate-like metal members 4 (not shown).

[0020] Both end surfaces of the plate-like metal members 4 are connected by soldering so as to be respectively held in contact with the corresponding component lands 7 to form coil portions each including the plate-like metal member 4 and the wiring pattern 8. A defined number of the coil portions are electrically connected to each other and arranged side by side along the middle leg portion of the core 3, thereby forming a coil body.

[0021] A distance between each of the component lands 7 that are a lowermost portion and an uppermost portion in FIG. 2 and a bridging portion of the wiring pattern 8, which connects the adjacent component lands 7, and a distance between the adjacent component lands 7 are defined as widths that allow the insulating resist to be interposed therebetween and allow insulation to be ensured for a voltage drop in the coil portion for one turn when a predetermined voltage is applied to a reactor.

[0022] The core 3 has a bottom surface placed on the metal-based printed wiring board 6.

[0023] Each of the insulating members 5 includes a semi-donut portion interposed between the adjacent plate-like metal members 4, which is obtained by halving a donut-shaped plate, a cylindrical portion having a cylindrical shape, which surrounds the middle leg portion of the core 3, and an outer-diameter side portion interposed between an outer-diameter side of the plate-like metal members 4 and an inner wall of the core 3.

[0024] In the reactor constructed as described above, the metal-based printed wiring board 6 on which the coil body is arranged is mounted onto the cooler. As a result, heat is efficiently radiated from the coil body, and hence increase in electrical resistance due to temperature rise of the coil body can be suppressed.

[0025] Further, the improvement of a heat radiating property allows the heat radiating area of the entire reactor to be reduced. Therefore, the core 3, the plate-like metal members 4, the metal-based printed wiring board 6, and the like constructing the reactor can be downsized and reduced in weight, and costs can also be reduced thereby.

[0026] Further, the cooler configured to cool the reactor can also be downsized and reduced in costs.

[0027] Further, the plate-like metal members 4 are plate-like members, and hence stable dimensional accuracy can be obtained. Therefore, variation in leakage inductance can be suppressed to suppress variation in loss of the coil body.

[0028] Further, the adjustment of an inductance is facilitated by adjusting the number of laminated coil portions, a plate width of the plate-like metal members 4 that are constituent elements of the coil body, a distance between the coil body and the core 3, and a gap between the first core portion 1 and the second core portion 2.

[0029] Further, the plate-like metal members 4 are connected to the component lands 7 on the metal-based printed wiring board 6 in a one-by-one manner. As a result, the plate-like metal members 4 are arranged so as to be separated away from each other so that the plate-like metal members 4 can individually radiate heat. Therefore, the reduction in thermal resistance and the improvement of the heat radiating property are enabled.

[0030] Further, the reactor main body is not required to be housed inside a metal case that is filled with a heat radiating resin to ensure a heat-radiation path unlike the reactor described in JP 2009-94328 A (Patent Literature 2). Therefore, downsizing, reduction in weight, and reduction in costs are enabled.

[0031] Further, the plate-like metal members 4 are connected to the component lands 7 for each one. As a result, stable dimensional accuracy is obtained between the coil portions that are the constituent elements of the coil body. Hence, variation in the thermal resistance and electric characteristics such as the inductance and the coil-body loss can be reduced.

[0032] Further, the tough-pitch copper members are used as the plate-like metal members 4. As a result, an electrical conductivity close to that of pure copper is obtained to enable realization of a low electric resistance as the coil body. At the same time, the generation of an eddy current along with a leakage flux generated from the reactor because each of the tough-pitch copper members is a non-magnetic metal and an eddy-current loss can be reduced.

[0033] Further, simultaneously with the suppression of a loss amount, the heat generated from the plate-like metal members 4 can be efficiently radiated through the metal-based printed wiring board 6 and the cooler because each of the tough-pitch copper members has a thermal conductivity close to that of pure copper. Further, downsizing and reduction in weight can be realized thereby.

[0034] Although a copper-based material is used in this embodiment, an aluminum-based material may also be used.

[0035] By using the aluminum-based material as the plate-like metal members 4 to be used for the coil body, the generation of the eddy current can be suppressed because the aluminum-based material is a non-magnetic metal although the aluminum-based material is inferior to the copper-based material in heat-radiating property and electrical conductivity. Further, because of a specific gravity extremely smaller than those of the other metals, significant reduction in weight can be realized particularly when the number of turns in the coil body is large.

[0036] Further, a unit price of the material is significantly lower than that of the copper-based material, and hence costs can also be reduced.

[0037] Further, the bottom surface of the core 3 is placed so as to be held in contact with the metal-based printed wiring board 6. As a result, lost heat (iron loss) generated in the core 3 can be radiated to the cooler through the metal-based printed wiring board 6.

[0038] Further, by interposing the insulating members 5 such as resin plates or insulating sheets between the plate-like metal members 4 and between the plate-like metal members 4 and the core 3 adjacent thereto, an insulating property between the adjacent plate-like metal members 4 and between the coil body and the core 3 is ensured. As a result, stable performance as the reactor can be obtained.

[0039] Further, when insulation distances between the plate-like metal members 4 and between the plate-like metal members 4 and the core 3 adjacent thereto are ensured, the insulating members 5 are not required to be interposed therebetween.

[0040] Further, although the plate-like metal members 4 are used as the constituent elements of the coil body in this embodiment, a round wire or a rectangular wire may be used in place of each of the plate-like metal members 4.

[0041] Further, although the metal-based printed wiring board 6 that is the constituent element of the coil body has been described in this embodiment, a ceramic-based printed wiring board may be used in place of the metal-based printed wiring board 6. By using the ceramic-based printed wiring board, the heat radiating property can be improved while ensuring a high insulating property. Further, downsizing and reduction in weight can be realized thereby.

[0042] Further, although the core 3 has been described as the shell-type core of the PQ type in this embodiment, the present invention is also applicable to other shell-type cores such as EI type, EE type, EER type, and ER type and core-type cores such as U-type.

Second Embodiment

[0043] FIG. 3 is a perspective view of a transformer according to a second embodiment of the present invention, and FIG. 4 is a top view of wiring patterns 17 and 19 on a metal-based printed wiring board 15 illustrated in FIG. 3. In FIG. 3, the illustration of a plurality of electronic components mounted on the metal-based printed wiring board 15 is omitted.

[0044] The transformer, which is an electromagnetic induction apparatus, includes a core 11 that is a U-shaped core including a first core portion 9 and a second core portion 10, plate-like metal members 12 for primary winding and plate-like metal members 13 for secondary winding each having a C-like shape and placed so as to surround one magnetic leg of the core 11, insulating members 14 configured to insulate the plate-like metal member 12 for primary winding and the plate-like metal member 13 for secondary winding from each other and the plate-like metal members 12 and 13 and the core 11 from each other, and the metal-based printed wiring board 15 having an upper surface on which wiring patterns 17 for primary winding and wiring patterns 18 for secondary winding are provided.

[0045] By placing and fixing the metal-based printed wiring board 15 onto a cooler (not shown), the transformer is fixed to the cooler.

[0046] The plate-like metal members 12 for primary winding are tough-pitch copper members having a prescribed electric resistance value.

[0047] The wiring patterns 17 for primary winding on the metal-based printed wiring board 15 have a prescribed electric resistance value, and are coated with an insulating resist except for component lands 16 for primary winding, each having a rectangular shape or the like. The wiring patterns 17 for primary winding are electrically connected through connecting portions (not shown).

[0048] Both end surfaces of the plate-like metal members 12 for primary winding are connected by soldering so as to be respectively held in contact with the component lands 16 for primary winding to form primary winding portions that are coil portions each including the plate-like metal member 12 for primary winding and the wiring pattern 17 for primary winding.

[0049] A defined number of the primary winding portions are electrically connected to each other and arranged side by side along one leg of the core 11, thereby forming a primary winding 20 that is a coil body.

[0050] The plate-like metal members 13 for secondary winding are tough-pitch copper members having a prescribed electric resistance value.

[0051] The wiring patterns 19 for secondary winding on the metal-based printed wiring board 15 have a prescribed electric resistance value, and are coated with an insulating resist except for component lands 18 for secondary winding, each having a rectangular shape or the like. The wiring patterns 19 for secondary winding are electrically connected through connecting portions (not shown).

[0052] Both end surfaces of the plate-like metal members 13 for secondary winding are connected by soldering so as to be respectively held in contact with the component lands 18 for secondary winding to form secondary winding portions that are coil portions each including the metal member 13 for secondary winding and the wiring pattern 19 for secondary winding.

[0053] A defined number of the secondary winding portions are electrically connected to each other and arranged side by side along one leg of the core 11, thereby forming a secondary winding 21 that is a coil body.

[0054] In this embodiment, in order to alternately arrange the plate-like metal members 12 for primary winding and the plate-like metal members 13 for secondary winding, the component lands 16 for primary winding of the wiring patterns 17 for primary winding and the component lands 18 for secondary winding of the wiring patterns 19 for secondary winding are shifted from each other by a distance d1 along an axial direction as illustrated in FIG. 4.

[0055] Further, in order to ensure an insulation distance between the wiring patterns 17 for primary winding and the wiring patterns 19 for secondary winding that are adjacent to each other, the wiring patterns 17 for primary winding and the wiring patterns 19 for secondary winding are provided so as to be separated away from each other by a predetermined distance d2 as illustrated in FIG. 4.

[0056] In the transformer constructed as described above, the metal-based printed wiring board 15 on which the primary winding 20 and the secondary winding 21 are arranged is mounted onto the cooler. Therefore, heat can be efficiently radiated from the primary winding 20 and the secondary winding 21. Thus, increase in thermal resistance due to temperature rise of the primary winding 20 and the secondary winding 21 can be suppressed.

[0057] Further, the improvement of the heat radiating property allows the heat radiating area of the entire transformer to be reduced. Therefore, the core 11, the plate-like metal members 12 for primary winding, the plate-like metal members 13 for secondary winding, the metal-based printed wiring board 15, and the like constructing the transformer can be downsized and reduced in weight, and costs can be reduced thereby.

[0058] Further, each of the plate-like metal members 12 for primary winding and the plate-like metal members 13 for secondary winding is a plate-like member. Therefore, stable dimensional accuracy can be obtained. Thus, variation in leakage inductance can be suppressed to suppress variation in loss of the primary winding 20 and the secondary winding 21.

[0059] Further, by alternately arranging the plate-like metal members 12 for primary winding and the plate-like metal members 13 for secondary winding, the transformer with a high degree of coupling can be realized. As a result, the leakage inductance can be suppressed.

[0060] Further, the adjustment of an excitation inductance and the leakage inductance is facilitated by adjusting the number of laminated coil portions, a plate width of the plate-like metal members 12 for primary winding and the plate-like metal members 13 for secondary winding, a distance between each of the primary winding 20 and the second winding 21 and the core 11, and a gap between the first core portion 9 and the second core portion 10.

[0061] Further, the plate-like metal members 12 for primary winding and the plate-like metal members 13 for secondary winding are connected onto the component lands 16 and 18 on the metal-based printed wiring board 15 in a one-by-one manner. As a result, the heat is radiated individually from each of the plate-like metal members 12 for primary winding and the plate-like metal members 13 for secondary winding. Therefore, the reduction in thermal resistance and the improvement of the heat radiating property are enabled.

[0062] Further, the plate-like metal members 12 for primary winding and the plate-like metal members 13 for secondary winding are connected to the component lands 16 and 18 for each one. Thus, the stable dimensional accuracy of the distance can be obtained between the primary winding 20 and the secondary winding 21. As a result, variation in the thermal resistance and the electric characteristics such as the excitation inductance, the leakage inductance, and the loss can be reduced.

[0063] Further, the tough-pitch copper members are used as the plate-like metal members 12 for primary winding and the plate-like metal members 13 for secondary winding. As result, an electric conductivity close to that of pure copper is obtained to enable the realization of a low electric resistance as the primary winding 20 and the secondary winding 21. At the same time, the generation of an eddy current along with a leakage flux generated from the transformer because each of the tough-pitch copper members is a non-magnetic metal and an eddy-current loss can be reduced.

[0064] Further, simultaneously with the suppression of a loss amount, the heat generated from the plate-like metal members 12 for primary winding and the plate-like metal members 13 for secondary winding can be efficiently radiated through the metal-based printed wiring board 15 and the cooler because each of the tough-pitch copper members has a thermal conductivity close to that of pure copper. Further, downsizing and reduction in weight can be realized thereby.

[0065] Further, by interposing the insulating members 14 such as resin plates or insulating sheets between the plate-like metal member 12 and the plate-like metal member 13 and between the plate-like metal members 12 and 13 and the core 11 adjacent thereto, an insulating property between the primary winding 20 and the secondary winding 21, between the plate-like metal members 12 and 13, and between each of the primary winding 20 and the second winding 21 and the core 11 is ensured. As a result, stable performance as the transformer can be obtained.

[0066] Further, ease of assembly can also be improved.

[0067] The plate-like metal members 12 that are the constituent elements of the primary winding 20 and the plate-like metal members 13 that are the constituent elements of the secondary winding 21 may also be molded with a resin to ensure the insulating property.

[0068] Further, for a predetermined voltage to be applied to the transformer, a distance that allows the insulation between the wiring patterns 17 for primary winding and the wiring patterns 19 for secondary winding is provided. As a result, the insulating property between the primary winding 20 and the secondary winding 21 is ensured to provide the stable performance as the transformer.

[0069] Although the copper-based material is used for both the plate-like metal members 12 and 13 in this embodiment, an aluminum-based material may also be used as in the first embodiment.

[0070] Further, although the metal-based printed wiring board 15 has been described as the printed wiring board in this embodiment, a ceramic-based printed wiring board may be used as in the second embodiment.

[0071] Further, although a step-up transformer in which the number of turns in the secondary winding 21 is larger than that of the primary winding 20 has been described in this embodiment, the present invention is also applicable to a step-down transformer in which the number of turns in the primary winding is larger than that of the secondary winding.

[0072] Further, although the core 11 has been described as the core-type core of the U-type in this embodiment, the present invention is also applicable to shell-type cores such as EI type, EE type, EER type, and ER type.

Third Embodiment

[0073] FIG. 5A is a diagram for schematically illustrating an example of arrangement of primary winding portions 20a and secondary winding portions 21 a of a transformer, and FIG. 5B is a diagram for schematically illustrating the arrangement of the primary winding portions 20a and the secondary winding portions 21 a of a transformer according to a third embodiment of the present invention.

[0074] When a transformation ratio of the transformer is large, the number of the primary winding portions 20a and the number of the secondary winding portions 21a sometimes become greatly different from each other. For example, as illustrated in FIG. 5A, three secondary winding portions 21a are consecutively adjacent to each other. As a result, the leakage inductance of the transformer increases to increase the loss of the transformer.

[0075] On the other hand, as illustrated in FIG. 5B, the secondary winding portions 21 a are arranged so that up to two thereof are adjacent to each other. As a result, increase in the leakage inductance of the transformer is suppressed. Further, the degree of coupling is high while the loss can be suppressed.

[0076] The remaining configuration is the same as that of the transformer of the second embodiment.

[0077] Although the reactor and the transformer have been described as the electromagnetic induction apparatus in the embodiments described above, a choke coil may also be used instead.

[0078] Further, although the cooler in which refrigerant flows into the interior of the pipe has been described as an example of cooling means for cooling the electromagnetic induction apparatus, a heat sink may also be used instead.

Reference Signs List

[0079] 1 first core portion, 2 second core portion, 3, 11 core, 4 plate-like metal member (metal member), 5, 14 insulating member, 6, 15 metal-based printed wiring board, 7 component land, 8 wiring pattern, 9 first core portion, 10 second core portion, 12 plate-like metal member for primary winding (metal member), 13 plate-like metal member for secondary winding (metal member), 16 component land for primary winding, 17 wiring pattern for primary winding, 18 component land for secondary winding, 19 wiring pattern for secondary winding (wiring pattern), 20 primary winding (coil body), 20a primary winding portion (coil portion), 21 secondary winding (coil body), 21 a secondary winding portion (coil portion)

Claims

1. An electromagnetic induction apparatus, comprising:

a core forming a closed magnetic path;

a printed wiring board configured to support the core, the printed wiring board comprising a plurality of wiring patterns; and

a metal member provided around the core and having both end portions connected to the plurality of wiring patterns,

wherein a plurality of coil portions including the plurality of wiring patterns and the metal member are electrically connected to each other and arranged side by side to form a coil body.

2. An electromagnetic induction apparatus according to claim 1, wherein the metal member comprises plate-like metal members.

3. An electromagnetic induction apparatus according to claim 2, further comprising insulating members interposed between the plate-like metal members adjacent to each other and between the plate-like metal members and the core.

4. An electromagnetic induction apparatus according to claim 1, wherein the metal member comprises a round wire.

5. An electromagnetic induction apparatus according to claim 1, wherein the metal member comprises a rectangular wire.

6. An electromagnetic induction apparatus according to any one of claims 1 to 5, wherein the metal member surrounds the core by 360 degrees.

7. An electromagnetic induction apparatus according to any one of claims 1 to 6, wherein the metal member is connected to the printed wiring board by soldering.

8. An electromagnetic induction apparatus according to any one of claims 1 to 7, wherein the metal member is made of copper.

9. An electromagnetic induction apparatus according to any one of claims 1 to 7, wherein the metal member is made of aluminum.

10. An electromagnetic induction apparatus according to any one of claims 1 to 9, wherein the printed wiring board comprises a metal-based printed wiring board.

11. An electromagnetic induction apparatus according to any one of claims 1 to 9, wherein the printed wiring board comprises a ceramic-based printed wiring board.

12. An electromagnetic induction apparatus according to any one of claims 1 to 11, wherein the core is held in surface contact with the printed wiring board.

13. An electromagnetic induction apparatus according to any one of claims 1 to 12, wherein:

the electromagnetic induction apparatus comprises a transformer; and

the coil body comprises:

a primary winding comprising primary winding portions corresponding to the plurality of coil portions; and

a secondary winding comprising secondary winding portions corresponding to the plurality of coil portions.

14. An electromagnetic induction apparatus according to claim 13, wherein the primary winding portions and the secondary winding portions are arranged side by side alternately.

15. An electromagnetic induction apparatus according to claim 13, wherein the primary winding portions and the secondary winding portions are each arranged so that up to two of the primary winding portions or the secondary winding portions are adjacent to each other.

16. An electromagnetic induction apparatus according to any one of claims 13 to 15, further comprising:

a component land for primary winding on each of the plurality of wiring patterns to which a plate-like metal member for primary winding that is a constituent element of each of the primary winding portions is connected; and

a component land for secondary winding on each of the plurality of wiring patterns to which a plate-like metal member for secondary winding that is a constituent element of each of the secondary winding portions is connected,

the component land for secondary winding being adjacent to the component land for primary winding,

the component land for primary winding and the component land for secondary winding being separated away from each other with an insulation distance therebetween.

17. An electromagnetic induction apparatus according to claim 16, further comprising insulating members interposed between the plate-like metal member for primary winding and the plate-like metal member for secondary winding, between the plate-like metal member for primary winding and the core, and between the plate-like metal member for secondary winding and the core.

18. An electromagnetic induction apparatus according to claim 17, wherein the insulating members comprise resin plates.

19. An electromagnetic induction apparatus according to claim 17, wherein the insulating members comprise resin sheets.

20. An electromagnetic induction apparatus according to claim 17, wherein the plate-like metal member for primary winding and the plate-like metal member for secondary winding are molded with a resin.

21. An electromagnetic induction apparatus according to any one of claims 1 to 20, wherein cooling means for cooling the electromagnetic induction apparatus is mounted onto the printed wiring board.

Drawing