JP6961971B2 - Coil device - Google Patents

Description

The present invention relates to a coil device that can also be suitably used as a switching power supply such as an AC-DC power supply, for example, a noise filter used in an AC-DC power supply for charging an in-vehicle battery.

For example, the following Patent Document 1 is known as a transformer used for charging a battery for EV. As described above, a high current is applied to a transformer used in a vehicle or the like, and heat dissipation measures are required.

In the conventionally proposed coil device, the bobbin and the magnetic core and the heat radiating member are connected to each other so that heat can be transferred at the bobbin installation part or the core installation part, so that the inside of the bobbin or the magnetic core around which the coil that generates heat is wound is wound. It is possible to satisfactorily transfer the heat accumulated in the bobbin and the core installation portion from the bobbin and the magnetic core to the heat radiating member and dissipate the heat from the heat radiating member.

Japanese Unexamined Patent Publication No. 2016-139699

For cooling the noise filter used in the AC-DC power supply for charging the in-vehicle battery, a natural cooling system may be adopted instead of the water cooling system used for cooling the in-vehicle transformer. There are differences in the cooling system adopted depending on the application. Therefore, as a coil device that can be used for such applications, a coil device having further improved heat dissipation characteristics is required.

The present invention has been made in view of such an actual situation, and an object of the present invention is to provide a coil device capable of coping with a large current of the coil device by improving heat dissipation.

In order to achieve the above object, the coil device according to the present invention
A coil device having a magnetic core, a bobbin, and a coil mounted on the bobbin.
It has a heat radiating member arranged so as to face the two bobbin bottoms of the bobbin and the core bottom of the magnetic core arranged so as to be sandwiched inside the two bobbin bottoms.
The bottom of the bobbin is formed with an uneven shape that forms a heat dissipation path with the heat dissipation member.
The heat dissipation path is continuous from the outer side surface of the bobbin bottom to the core bottom.

In the coil device of the present invention in which a concave-convex shape forming a heat dissipation path is formed on the bottom of the bobbin, the heat dissipation characteristics from the bobbin are greatly improved. That is, by forming the uneven shape, the contact area with the heat dissipation path is increased, and the heat dissipation characteristics are improved. Further, since the uneven shape is formed, the wall thickness of the resin constituting the bottom of the bobbin can be reduced, so that the heat dissipation characteristics are improved as compared with the conventional bobbin. For example, when a resin containing a filler for improving thermal conductivity is used as the resin constituting the bobbin, there may be a problem that the thermal conductivity in the thickness direction is not sufficiently improved due to the orientation of the filler. The coil device of the present invention having a thin bobbin bottom can prevent such a problem.

Furthermore, since the heat dissipation path is continuous from the outer side surface of the bobbin to the bottom of the core, the heat around the bottom of the core is dissipated through the heat dissipation path, so that the heat dissipation characteristics from the magnetic core and coil near the bottom of the core are dissipated. Is improved. In addition to heat dissipation through the heat dissipation member, heat dissipation from the outer side surface of the bobbin is improved, so heat can be dissipated not only from the water cooling system that intensively releases heat from the heat dissipation member but also from parts other than the heat dissipation member. Even when the required natural cooling system is adopted, the coil device of the present invention exhibits good heat dissipation characteristics.

Further, for example, at least a part of the heat dissipation path may be filled with the potting resin.

By filling the heat dissipation path with a resin having a higher thermal conductivity than air, heat exchange between the bottom of the bobbin and the heat dissipation member becomes efficient, particularly through the potting resin, in such a coil device. It is also believed that a system that dissipates heat from the bottom of the core from the outer side surface of the bobbin via the heat dissipation path will be more efficient via the potting resin. Therefore, such a coil device exhibits good heat dissipation characteristics.

Further, for example, the uneven shape may have fin-shaped protrusions that continue from the inner side surface of the bobbin bottom portion toward the outer side surface and project toward the heat radiating member.

Since the concave-convex shape has fin-shaped protrusions, a heat dissipation path is formed to improve heat dissipation characteristics, and the bobbin itself can also dissipate heat by taking advantage of its high thermal conductivity in the direction perpendicular to the wall thickness direction. can. Therefore, such a coil device exhibits good heat dissipation characteristics.

Further, for example, the uneven shape may have a plurality of columnar protrusions that are intermittently provided from the inner side surface of the bobbin bottom portion to the outer side surface and project toward the heat radiating member.

Since the concave-convex shape has a plurality of columnar protrusions, it is possible to form a heat dissipation path to improve heat dissipation characteristics, effectively increase the surface area of the bobbin bottom, and expand the contact area between the bobbin bottom and the heat dissipation path. .. Therefore, such a coil device exhibits good heat dissipation characteristics.

Further, for example, the heat dissipation path includes a first heat dissipation path provided between the bobbin bottom of one of the two bobbin bottoms and the heat dissipation member, and the other bobbin bottom of the two bobbin bottoms and the heat dissipation member. The potting resin may have a second heat radiating path provided between the heat radiating members, and may connect the first heat radiating path and the second heat radiating path.

By connecting the first heat dissipation path and the second heat dissipation path with the potting resin, it is possible to effectively prevent the problem that a portion where heat is locally accumulated is generated in a part of the coil device. Further, when the potting resin connecting the first heat radiation path and the second heat radiation path comes into contact with the bottom of the core, such a coil device can efficiently dissipate heat from the magnetic core.

FIG. 1 is a perspective view of a coil device according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the coil device shown in FIG. FIG. 3 is a perspective view showing a bobbin bottom portion and a core bottom portion in the coil device shown in FIG. FIG. 4 is a cross-sectional view showing a heat dissipation path and a potting resin satisfying the heat dissipation path in the coil device shown in FIG. FIG. 5 is a cross-sectional perspective view of the coil device, which is perpendicular to the mounting surface and has a cross section taken along the line VV shown in FIG. FIG. 6 is a cross-sectional perspective view of the coil device, which is perpendicular to the mounting surface and has a cross section taken along the line VI-VI shown in FIG. FIG. 7 is a cross-sectional view of the coil device according to another embodiment of the present invention, and is a cross-sectional view corresponding to FIG.

Hereinafter, the present invention will be described based on the embodiments shown in the drawings.

First Embodiment As shown in FIGS. 1 and 2, the coil device 10 according to the present embodiment is used as an AC-DC power supply for charging an in-vehicle battery, for example, as a noise filter or the like. However, the application of the coil device 10 is not limited to this, and it may be used as an in-vehicle transformer for charging a battery of a PHV or EV. As shown in FIG. 2, the coil device 10 includes a bobbin 20, a magnetic core 40, and a heat sink 80. Further, although not shown in FIG. 2, in the coil device 10, as shown in FIGS. 5 and 6 which are cross-sectional views, the first wire 37 and the second wire 38 constituting the coil and the potting resin 90 are provided. Have. In FIG. 2, the first wire 37, the second wire 38, and the potting resin 90 in the coil device 10 are not shown.

As shown in FIG. 2, the bobbin 20 is connected to the winding cylinder portion 26 above the winding cylinder portion 26 (on the positive direction side of the Z axis) and is integrated with the winding cylinder portion 26. It has 29, a lead wire installation portion 22, an end partition wall collar 28 connected below the winding cylinder portion 26 and integrated with the winding cylinder portion 26, and a bobbin bottom portion 21. Above the bobbin 20, two lead wire installation portions 22 provided at both ends in the X-axis direction are provided, and below the bobbin 20, two bobbin bottoms 21 are provided at both ends in the X-axis direction. The lead portion of the first wire 37 and the lead portion of the second wire 38, which will be described later, are installed in the lead wire installation portion 22. Further, the lead portions of the first wire 37 and the second wire 38 installed in the lead wire installation portion 22 are covered by the lead wire insulating cover 54 provided on the bobbin 20.

As shown in FIG. 2, in the present embodiment, the magnetic core 40 has an upper core 40a and a lower core 40b. The upper core 40a and the lower core 40b can be separated into two split cores 42a, 42a and 42b, 42b having the same shape, respectively. In the present embodiment, the divided cores 42a, 42a and 42b, 42b all have the same shape, have a U-shaped cross section in a ZZ cross section, and are a kind of U-shaped core.

By combining the pair of split cores 42a and 42a arranged in the upper part in the Z-axis direction, the upper core 40a which has an E-shaped cross section in the ZZ cross section and is a so-called E-shaped core is formed. The other pair of split cores 42b and 42b arranged in the lower part in the Z-axis direction are also combined to form a lower core 40b which has an E-shaped cross section in a ZZ cross section and is a so-called E-shaped core. ..

Each of the divided cores 42a arranged on the upper side in the Z-axis direction has an upper base portion 44a extending in the Y-axis direction and a pair of middle leg portions 46a protruding in the Z-axis direction from both ends of the upper base portion 44a in the Y-axis direction. And has side legs 48a. Each of the divided cores 42b arranged on the lower side in the Z-axis direction is a pair of a lower base portion 44b as a core bottom extending in the Y-axis direction and a pair of lower base portions 44b protruding in the Z-axis direction from both ends in the Y-axis direction. It has a middle leg portion 46b and a side leg portion 48b.

As shown in FIG. 2, the pair of middle leg portions 46a are inserted into the core leg through hole 26a penetrating the winding cylinder portion 26 of the bobbin 20 from above in the Z-axis direction. Similarly, the pair of middle leg portions 46b are inserted into the core leg through hole 26a of the bobbin 20 from below in the Z-axis direction, and inside the core leg through hole 26a, their tips are the middle leg portions. It is configured to contact the tip of 46a or face it with a predetermined gap.

Inside the core leg through hole 26a, a separation plate portion 27 (see FIG. 2) or a convex portion is formed along the X-axis direction so as to divide the core leg through hole 26a in the Y-axis direction at the central portion. It may be formed along the Z-axis direction. The separation plate portion 27 (the same applies to the convex portion) is interposed between the pair of middle leg portions 46a, 46a and between the middle leg portions 46b, 46b, and these middle leg portions 46a, 46a or The middle leg portions 46b and 46b are configured to face each other with a predetermined gap inside the core leg through hole 26a so as not to come into contact with each other. The predetermined gap can be adjusted by adjusting the thickness of the separation plate portion 27 in the Y-axis direction.

The middle leg portions 46a, 46a or the middle leg portions 46b, 46b, respectively, have an elliptical column shape long in the X-axis direction so as to match the shape of the inner peripheral surface of the core leg through hole 26a in a combined state. However, the shape is not particularly limited, and may be changed according to the shape of the core leg through hole 26a. Further, the side leg portions 48a and 48b have an inner concave curved surface shape that matches the outer peripheral surface shape of the winding cylinder portion 26, and the outer surface thereof has a plane parallel to the XZ plane. In the present embodiment, the materials of the divided cores 42a and 42b include soft magnetic materials such as metal and ferrite, but are not particularly limited.

In the drawings, the X-axis, the Y-axis, and the Z-axis are perpendicular to each other, and the Z-axis coincides with the winding axes of the first wire 37 and the second wire 38, which will be described later, and the height of the coil device 10 ( Corresponds to (thickness). In the present embodiment, the lower part of the coil device 10 in the Z-axis direction is the heat sink 80 (installation surface of the coil device 10) of the coil device 10. Further, the Y-axis coincides with the direction in which the pair of split cores 42a, 42a or the pair of split cores 42b, 42b are split. Further, the X-axis coincides with the longitudinal direction of the middle legs 46a and 46b (the major axis direction of the ellipse in the elliptical column).

As shown in FIGS. 2, 5 and 6, end partition wall collars 28 and 29 are connected to both ends of the winding cylinder portion 26 of the bobbin 20 in the coil device 10 of the present embodiment in the Z-axis direction. .. The end bulkhead collars 28 and 29 are formed substantially parallel to the XY plane so as to extend outward in the radial direction from the winding cylinder portion 26. On the outer peripheral surface of the winding cylinder portion 26 located between the end bulkhead collars 28 and 29 in the Z-axis direction, the winding bulkhead collars 23 to 25 are predetermined in the Z-axis direction so as to project outward in the radial direction. It is formed at intervals. Since the cross section shown in FIGS. 5 and 6 is a cross section that passes through a position away from the center of the coil device 10 as shown in FIG. 4, FIG. 5 and FIG. 6 show the inside of the magnetic core 40. The legs 46a and 46b do not appear.

Between the end bulkhead collars 28, 29 and the wound bulkhead collars 23-25 formed between the end bulkhead collars 28, 29, between these end bulkhead collars 29, 29 and the wound bulkhead collars 23-25. As shown in FIG. 5, four winding compartments S1 to S4 are formed in this order from the bottom in the Z-axis direction. The number of winding bulkhead collars 23 to 25 and winding compartments S1 to S4 is not particularly limited.

In the present embodiment, as shown in FIGS. 5 and 6, the first wire 37 is continuously wound in the winding sections S1 and S2, and the second wire 38 is continuously wound in the winding sections S3 to S4. It is wound around. In the present embodiment, the first wire 37 constitutes the primary coil and the second wire 38 constitutes the secondary coil, but the reverse may be true. Although the first wire 37 and the second wire 38 are shown in a simplified manner in FIGS. 5 and 6, the first wire 37 and the second wire 38 are predetermined around the winding cylinder portion 26. It is wound in a spiral shape according to the number of turns.

Further, in the present embodiment, the winding partition wall 23 shown in FIG. 5 is formed with a connecting groove that connects the winding compartments S1 and the winding compartments S2 that are vertically adjacent to each other. The first wire 37 wound around the winding section S1 is passed through the winding section S2 through the connecting groove, and the first wire 37 is placed on the outer periphery of the winding tube portion 26 of the bobbin 20 in the winding sections S1 and S2. It can be wound.

Similarly, the winding partition wall 25 shown in FIG. 5 is formed with a connecting groove that connects the winding compartments S3 and the winding compartments S4 that are vertically adjacent to each other. The second wire 38 wound around the winding section S3 is passed through the winding section S4 through the connecting groove, and the second wire 38 is placed on the outer periphery of the winding tube portion 26 of the bobbin 20 in the winding sections S3 and S4. It can be wound.

Regarding the wound bulkhead collar 24, in order to insulate the first wire 37 and the second wire 38, it is not necessary to form a connecting groove similar to these. The connecting groove for the first wire 37 and the connecting groove for the second wire 38 are preferably formed on opposite sides in the X-axis direction, but are not particularly limited. As shown in FIG. 2, on the side of the bobbin 20, the first wire 37 and the second wire 38 wound in the winding compartments S1 to S4, and the side legs 48a and 48b of the magnetic core 40 are provided. A side insulating cover 50 for insulating the wire is attached.

As shown in FIG. 5, the section width T1 along the Z axis in each winding section S1 and S2 around which the first wire 37 is wound has a width that allows only one first wire 37 to enter in the Z axis direction. It has been set. However, the partition width T1 may be set to a width that allows two or more first wires 37 to enter. Further, in the present embodiment, the compartment widths T1 are all preferably the same, but may be slightly different.

Further, the section width T2 along the Z axis in each of the winding sections S3 and S4 around which the second wire 38 is wound is set to a width that allows only one second wire 38 to enter in the Z axis direction. The wire winding portions can be separated from each other in each winding section S3 and S4. In the present embodiment, the section width T2 along the Z axis in each of the winding sections S3 and S4 may be the same as or different from the section width T1 according to the wire diameter of the second wire 38.

Further, the heights of the end partition collars 28 and 29 and the winding partition collars 23 to 25 (the length in the radial direction from the winding cylinder 26) are one or more (one or more layers) of the first wire 37 or the first wire 37 or the first. The height is set so that the two wires 38 can be inserted, and in the present embodiment, the height is preferably set so that 2 to 8 layers of wires can be wound. The heights of the end bulkhead collars 28 and 29 and the wound bulkhead collars 23 to 25 are all preferably the same, but may be different. In the present embodiment, the winding method of the first wire 37 or the second wire 38 wound in the winding compartments S1 to S4 is not particularly limited, and may be normal winding or α winding.

The first wire 37 and the second wire 38 may be composed of a single wire or a stranded wire, and are preferably composed of an insulating coated conductor. The outer diameters of the first wire 37 and the second wire 38 are not particularly limited, but are preferably φ1.0 to φ3.0 mm, for example, when a large current is passed. The second wire 38 may be the same as the first wire 37, but may be different.

The heat sink 80, the case 88, and the potting resin 90 are removed from the coil device 10, and as shown in FIG. The 44b is arranged inside the two bobbin bottoms 21 so as to be sandwiched on both sides in the X-axis direction. As shown in FIG. 5 which is a cross-sectional view, the two bobbin bottom portions 21 and the lower base portion 44b arranged between the bobbin bottom portions 21 face the heat radiating plate 80 as a heat radiating member.

As shown in FIG. 3, a concave-convex shape 21a is formed on the bobbin bottom portion 21. The concave-convex shape 21a has a plurality of fin-shaped protrusions 21aa extending parallel to each other along the X-axis direction. As shown in FIG. 5, the fin-shaped protrusions 21aa continue from the inner side surface 21c sandwiching the lower base portion 44b at the bobbin bottom portion 21 toward the outer side surface 21b which is both ends in the X-axis direction. Further, the fin-shaped protrusions 21aa project from the end partition wall 28 toward the heat sink 80 in the negative Z-axis direction, and as shown in FIG. 6, the plurality of fin-shaped protrusions 21aa are predetermined in the Y-axis direction. They are arranged at intervals.

As shown in FIG. 4 in which the coil device 10 shown in FIG. 1 is observed in a cross section orthogonal to the Z axis, the concave-convex shape 21a of the bobbin bottom 21 is between the coil device 10 and the heat sink 80 facing downward (in the positive direction of the Z axis). In addition, a heat dissipation path 92 is formed. As shown in FIG. 4, the heat dissipation path 92 is filled with the potting resin 90. As shown in FIGS. 4 and 6, the heat dissipation path 92 is formed between the recesses in the concave-convex shape 21a, that is, between two adjacent fin-shaped protrusions 21aa. As shown in FIG. 4, since the fin-shaped protrusions 21aa are formed parallel to the X-axis, the heat dissipation path 92 is continuous from the outer side surface 21b of the bobbin bottom portion 21 to the lower base portion 44b.

As shown in FIG. 4, the heat dissipation path 92 includes a first heat dissipation path 92a provided between one of the two bobbin bottoms 21 arranged on the negative side of the X-axis and the heat sink 80. It has a second heat radiating path 92b provided between the other bobbin bottom 21 arranged on the positive direction side of the X axis and the heat radiating plate 80 of the two bobbin bottoms 21. Both the first heat radiation path 92a and the second heat radiation path 92b are filled with the potting resin 90, and the potting resin 90 connects the first heat radiation path 92a and the second heat radiation path 92b. In the present embodiment, the potting resin 90 not only connects the first heat radiation path 92a and the second heat radiation path 92b on the outer circumference of the lower base portion 44b, but also passes through the gap of the divided lower base portion 44b. The first heat dissipation path 92a and the second heat dissipation path 92b are also connected at the center of the lower base portion 44b.

As shown in FIG. 5, the tip of the fin-shaped protrusion 21aa is arranged with a slight gap from the heat sink 80 so that a layer of the potting resin 90 is formed between the fin-shaped protrusion 21aa and the heat sink 80. Is preferable. For example, by making the protruding length of the fin-shaped protrusion 21aa in the Z direction slightly shorter than the length (thickness) of the lower base portion 44b sandwiched between the bobbin bottoms 21 in the Z direction, the tip of the fin-shaped protrusion 21aa and the tip of the fin-shaped protrusion 21aa are formed. A layer of the potting resin 90 can be formed between the heat radiating plate 80 and the heat radiating plate 80. Further, by making the protruding length of the fin-shaped protrusion 21aa in the Z direction shorter than the length of the lower base portion 44b in the Z direction, the manufacturing error of the divided cores 42a and 42b constituting the magnetic core 40 and the manufacturing error of the bobbin Even if there is, the adhesion between the magnetic core 40 and the bobbin 20 is improved, and the heat transfer characteristics are improved. Further, the lower base portion 44b of the magnetic core 40 may be in direct contact with the heat radiating plate 80, or may be connected via a potting resin 90.

As the potting resin 90, a general silicon-based or epoxy-based potting resin can be adopted, but the type of the potting resin 90 is not particularly limited. Further, as shown in FIG. 4, the potting resin 90 may completely fill the heat dissipation path 92 formed by the uneven shape 21a of the bobbin bottom 21, but a part of the heat dissipation path 92 is filled with the potting resin 90. The other part of the heat dissipation path 92 may be filled with air. The potting resin 90 functions as a heat transfer material for dissipating heat from the magnetic core 40, the bobbin 20, the first wire 37 and the second wire 38, and also connects the magnetic core 40 and the bobbin 20 with the heat sink 80. It also functions as a connecting member.

The bobbin 20 is made of plastic such as PPS, PET, PBT, LCP, and nylon, but may be made of other insulating members. However, in the present embodiment, the bobbin 20 is preferably made of, for example, a plastic having a thermal conductivity of 1 W / m · K or more, and is made of, for example, PPS, nylon, or the like. Further, it is preferable that the material constituting the bobbin 20 contains a filler for enhancing thermal conductivity in addition to the plastic.

As shown in FIG. 5, the heat radiating plate 80 as a heat radiating member is located on the bottom surface of the coil device 10 so as to face the two bobbin bottoms 21 and the lower base portion 44b sandwiched inside the bobbin bottoms 21. Is located in. A frame-shaped case 88 is attached to the Z-axis positive direction side of the heat sink 80, and a magnetic core 40, a bobbin 20, and a first wire are provided in a substantially rectangular parallelepiped space surrounded by the heat sink 80 and the case 88. 37, the second wire 38 and the like are arranged. The gap formed between the heat radiating plate 80 and the case 88 and the magnetic core 40, the bobbin 20, and the like housed inside is filled with the potting resin 90.

The heat radiating plate 80 shown in FIG. 2 is made of a member having high thermal conductivity such as metal. The material of the case 88 is not particularly limited, but it can be made of resin, metal, or the like. For example, by making the case 88 made of metal like the heat sink 80, it can be seen from the outer peripheral side surface of the coil device 10. The heat dissipation characteristics can be improved.

In the present embodiment, as shown in FIG. 5, the bobbin bottom portion 21 sandwiching the lower base portion 44b of the magnetic core 40 from both sides in the X-axis direction is connected to the heat radiating plate 80 so as to transfer heat. Therefore, the heat accumulated inside the bobbin 20 around which the coiled first wire 37 or the second wire 38 that generates heat is wound is satisfactorily transferred from the bobbin 20 to the heat sink 80 via the bobbin bottom 21. , It is possible to prevent an excessive temperature rise of the coil device 10.

Further, the magnetic core 40 is connected to the heat radiating plate 80 so as to be heat transferable. Therefore, the heat accumulated inside the bobbin 20 around which the coiled first wire 37 or the second wire 38 that generates heat is transferred from the bobbin 20 to the magnetic core 40 is transferred from the magnetic core 40 to the heat radiating plate 80. The heat of the coil device 10 is dissipated.

Further, since the bobbin bottom portion 21 of the coil device 10 of the present embodiment is formed with a concave-convex shape 21a forming the heat dissipation path 92 as shown in FIG. 4, the heat dissipation characteristics from the bobbin 20 and the magnetic core 40 are excellent. ing. That is, in the coil device 10, the uneven shape 21a is formed, so that the contact area with the heat dissipation path 92 is increased, and the heat dissipation characteristics are improved. Further, when a plastic containing a conductive filler is used as the material of the bobbin 20, heat is dissipated from the bobbin bottom 21 by forming the concave-convex shape 21a and reducing the wall thickness of the resin constituting the bobbin bottom 21. The characteristics can be improved. This is because even if the bobbin bottom has a simple wall thickness in order to bring the heat dissipation plate 80 closer to the bobbin, the thickness direction of the bobbin bottom (Z-axis positive direction) due to the orientation of the filler contained in the resin constituting the bobbin. ), The coil device 10 has a thin bobbin bottom 21 and good heat dissipation characteristics at the bobbin bottom 21.

Further, as shown in FIG. 4, the heat dissipation path 92 is continuous from the outer side surface 21b of the bobbin bottom portion 21 to the lower base portion 44b which is the core bottom portion, so that the heat around the lower base portion 44b passes through the heat dissipation path 92. Since heat is dissipated through the heat, the heat dissipation characteristics from the magnetic core 44 near the lower base portion 44b and the first wire 37 and the second wire 38 constituting the coil are improved. Further, not only the heat dissipation through the heat dissipation plate 80 but also the heat dissipation characteristics from the outer side surface of the bobbin 20 are improved. Even when a natural cooling system that is required to dissipate heat is adopted, the coil device 10 exhibits good heat dissipation characteristics.

Further, in the coil device 10, since the concave-convex shape 21a has the fin-shaped protrusions 21aa, the heat dissipation path 92 is formed between the fin-shaped protrusions 21aa to improve the heat dissipation characteristics, and the bobbin 20 itself also has a wall thickness direction. It is possible to dissipate heat by taking advantage of its high thermal conductivity in the vertical direction.

In the coil device 10, the heat accumulated inside the bobbin 20 around which the first wire 37 or the second wire 38 is wound follows the heat radiating plate 80, the heat radiating path 92, the potting resin 90, the case 88, and the like. It is diverged to the outside of 10. Therefore, it is possible to cope with a large current of the coil device 10, heat dissipation is improved, and deterioration of magnetic characteristics due to overheating of the coil portion can be suppressed.

Further, in the coil device 10 according to the present embodiment, the winding partition collars 23 to separate the wire winding portions adjacent to each other along the winding axis (Z axis) of the first wire 37 and the second wire 38. Since 25 is formed, insulation is easy even if the outer diameters of the first wire 37 and the second wire 38 are increased, and it is easy to cope with a large current (high output). Further, conventionally, as the voltage becomes higher, the wires adjacent to each other affect each other, which has an adverse effect that it becomes difficult for the current to flow. However, in the coil device 10 of the present embodiment, the wound partition blades 23 to 25 are used. Therefore, such an adverse effect can be reduced and the high frequency characteristics are also improved. Furthermore, since the end bulkhead collars 28 and 29 and the wound bulkhead collars 23 to 25 also act as heat radiation fins, the coil device 10 has excellent heat dissipation characteristics.

Further, in the present embodiment, in each of the compartments S1 to S4, the first wire 37 and the second wire 38 are wound so that only a single wire exists along the winding axis direction. It becomes easy to prevent variations in the number of turns of the 1st wire 37 and the 2nd wire 38, which contributes to the stabilization of the coil characteristics. That is, the coupling coefficient between the primary coil and the secondary coil can be strictly controlled.

Further, in the present embodiment, the divided middle leg portions 46a and 46b of the divided cores 42a and 42b divided into a U-shaped cross section are inserted into the core leg through holes 26a of the bobbin 20. According to experiments by the present inventors, even if the core becomes large, the intersection between the middle leg and the base is located at the intersection of the middle leg and the base as compared with the case where the conventional E-type core is used. The generated local stress can be dispersed. Therefore, in the coil device 10 according to the present embodiment, it is possible to effectively suppress the occurrence of cracks and the like even if thermal stress is generated in the core.

Further, the middle leg portions 46a and 46b, the upper base portion 44a and the lower base portion 44b in the E-shaped core formed by combining the divided cores 42a and 42b are separated by the divided surfaces of the divided cores 42a and 42b. It is possible to form a predetermined gap between the divided surfaces, and the heat dissipation is also improved. Further, the E-type core is formed by combining a pair of divided cores 42a and 42b, each of which has a simple shape, so that the core can be easily manufactured and the manufacturing cost can be reduced. Moreover, since the split type E-type core has the same magnetic field lines as the E-type core as a whole, the magnetic characteristics of the core are the same as those of the general E-type core.

Further, in the coil device 10, the heat dissipation path 92 is filled with a resin having a higher thermal conductivity than air, so that in such a coil device 10, heat exchange is particularly performed between the bobbin bottom 21 and the heat dissipation plate 80. , It becomes efficient through the potting resin 90. Further, it is considered that the mechanism for dissipating the heat of the lower base portion 44b from the outer side surface 21b of the bobbin bottom portion 21 via the heat dissipation path 92 will be more efficient via the potting resin 90. Therefore, such a coil device 10 exhibits good heat dissipation characteristics.

Further, in the coil device 10, as shown in FIG. 4, a portion where heat is locally accumulated in a part of the coil device 10 by connecting the first heat dissipation path 92a and the second heat dissipation path 92b by the potting resin 90. Can be effectively prevented. Further, when the potting resin 90 connecting the first heat radiation path 92a and the second heat radiation path 92b comes into contact with the lower base portion 44b, such a coil device 10 efficiently dissipates heat from the magnetic core 40. Can be done.

As described above, the present invention has been described with reference to embodiments, but the present invention is not limited to the above-described embodiments, and many other embodiments are included in the technical scope of the present invention. Needless to say. For example, in other embodiments, the mode of division of the magnetic core 40 may be changed. For example, in the coil device 10 described above, the magnetic core 40 is configured by the combination of the U core and the U core, which are the divided cores 42a and 42b, but the magnetic core may be assembled by the combination of the U core and the I core. Further, the shape and structure of the bobbin 20, the number of windings of the first wire 37 and the second wire 38, the winding method, and the like are not limited to the illustrated embodiments, and may be modified in various ways.

Further, for example, in the coil device 10 according to the first embodiment, the heat radiation path 92 is filled with the potting resin 90, but the heat radiation path 92 may be filled with another material or air. When a fluid such as air is present in the heat dissipation path 92, the heat dissipation of the coil device 10 can be improved by configuring the fluid so that the fluid can flow in the heat dissipation path 92.

Further, the concave-convex shape 21a formed on the bobbin bottom portion 21 may form a continuous heat dissipation path 92 from the outer side surface 21b of the bobbin bottom portion 21 to the lower base portion 44b, and has a fin shape shown in FIGS. 3 and 5. It is not limited to those having protrusions 21aa. FIG. 7 is a cross-sectional view of the coil device 110 according to the second embodiment of the present invention, and corresponds to FIG. 5 of the coil device 10 according to the first embodiment.

As shown in FIG. 7, the coil device 110 differs in that the concave-convex shape 121a on the bobbin bottom 121 of the bobbin 120 has a plurality of columnar protrusions 121aa instead of the fin-shaped protrusions 21aa as shown in FIG. The portion other than the concave-convex shape 121a is the same as that of the coil device 10 according to the first embodiment. Therefore, regarding the coil device 110, only the differences from the coil device 10 will be described, and the common points with the coil device 10 will be omitted.

As shown in FIG. 7, a concavo-convex shape 121a is formed on the bobbin bottom 121 of the coil device 110, and the concavo-convex shape 121a has a plurality of columnar protrusions 121aa protruding from the end partition wall 28 toward the heat radiating plate 80. Has. The columnar protrusions 121aa are intermittently provided from the inner side surface 121c of the bobbin bottom portion 121 to the outer side surface 121b.

Similarly to the coil device 10, the coil device 110 also has a heat dissipation path formed in the recess formed between the columnar protrusions 121aa, and the heat dissipation path is the bobbin bottom 21 as in the heat dissipation path 92 shown in FIG. It is continuous from the outer side surface 21b of the above to the lower base portion 44b. Further, the heat dissipation path of the coil device 110 is filled with the potting resin 90 as in the coil device 10. In such a coil device 110, since the concave-convex shape 121a has a plurality of columnar protrusions 121aa, a heat dissipation path is formed to improve heat dissipation characteristics, and the surface area of the bobbin bottom 121 is effectively expanded to effectively expand the bobbin bottom 121. The contact area between the bobbin and the heat dissipation path can be expanded. Therefore, the coil device 110 also has the same effect as the coil device 10 and has good heat dissipation characteristics.

10, 110 ... Coil device 20, 120 ... Bobbin 21, 121 ... Bobbin bottom 21a, 121a ... Concavo-convex shape 21aa ... Fin-shaped protrusion 121a ... Columnar protrusion 21b, 121b ... Outer side surface 21c, 121c ... Inner side surface 28, 29 ... End Barrier bobbin 22 ... Lead wire installation part 23, 24, 25 ... Winding partition bobbin 26 ... Winding tube part 26a ... Through hole for core legs 27 ... Separation plate part 37 ... 1st wire 38 ... 2nd wire 40 ... Magnetic Core 40a ... Upper core 40b ... Lower core 42a ... Split core 44a ... Upper base 44b ... Lower base 46a, 46b ... Middle legs 48a, 48b ... Side legs 50 ... Side insulation cover 54 ... Lead wire insulation cover 80 ... Heat dissipation plate 88 ... Case 90 ... Potting resin 92 ... Heat dissipation path 92a ... First heat dissipation path 92b ... Second heat dissipation path S1, S2, S3, S4 ... Winding section

Claims (4)

A coil device having a magnetic core, a bobbin, and a coil mounted on the bobbin.
A heat radiating member arranged so as to face the two bobbin bottoms of the bobbin and the core bottom of the magnetic core arranged inside the two bobbin bottoms.
The heat radiating member has a bobbin bottom and a frame-shaped case attached so as to surround the bobbin and the coil on a side facing the bottom of the core.
The bottom of the bobbin is formed with an uneven shape that forms a heat dissipation path with the heat dissipation member.
The heat dissipation path formed in the uneven concave portion is continuous from the outer side surface of the bobbin bottom to the core bottom.
A coil device including the heat radiating path, wherein a gap formed between the heat radiating member, the case, the magnetic core, and the bobbin is filled with a potting resin. The coil device according to claim 1, wherein the uneven shape has fin-shaped protrusions that continue from the inner side surface of the bottom of the bobbin toward the outer side surface and project toward the heat radiating member. The coil device according to claim 1, wherein the uneven shape is provided intermittently from the inner side surface of the bottom of the bobbin to the outer side surface and has a plurality of columnar protrusions protruding toward the heat radiating member. .. The heat dissipation path is between the first heat dissipation path provided between the bobbin bottom and the heat dissipation member of one of the two bobbin bottoms, and between the bobbin bottom and the heat dissipation member of the other of the two bobbin bottoms. Has a second heat dissipation path provided in
The coil device according to claim 1, wherein the potting resin connects the first heat radiation path and the second heat radiation path.

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