Coil device

Abstract

Provided is a coil device comprising: a magnetic core; a plurality of coil wound bodies wound onto the magnetic core such that surfaces forming the long side of a cross-section of a flat wire are stacked; a base stand part that supports the magnetic core having the coil wound bodies; and connection terminals that are provided on the base stand part and that respectively connect to end parts of the coil wound bodies. The connection terminals include plate-shaped electrodes that sandwich surfaces of the end parts led out from the coil wound bodies.

Description

[Technical field]

[0001] This technology relates to a coil device that is applied to common mode coils and choke coils that are mounted in power supply units and the like and are primarily used for EMC (Electro-Magnetic Compatibility) measures. [Background technology]

[0002] For example, with the increase in size of television receivers and the increase in brightness of projectors, coil devices are also required to handle higher power. For example, Patent Document 1 describes an invention related to a common choke coil. This common choke coil removes common mode noise. A common choke coil is formed by winding, for example, two conductors around a toroidal core to form two coils. The coils are wound in opposite directions, and when a common mode current flows through the coils, magnetic flux is generated in the same direction, and the magnetic fluxes strengthen each other to prevent the passage of the common mode current, thereby functioning as an inductor. On the other hand, when a differential mode current flows through the coil, the direction of the generated magnetic flux becomes opposite, and the magnetic fluxes cancel each other out, allowing the differential mode current to flow smoothly. In this way, it becomes a filter that does not function as an inductor for differential mode currents, but acts as an inductor only for common mode currents. The invention described in Patent Document 1 is a coil device that is vertically placed in order to reduce the installation space of the coil device on the board. In this case, the configuration of the coil and the connection terminal is devised. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-165219 A Summary of the Invention [Problem to be solved by the invention]

[0004] Problems that may arise when attempting to achieve high power output using the common mode coil structure and coil method as described in Patent Document 1 include the following. - As the amount of current increases, the loss in the conductor (coil) increases. Deterioration of filter performance due to the decrease in maximum number of turns caused by the increase in conductor diameter - Larger parts due to lower space factor -Increased costs due to decreased productivity

[0005] The conductor loss is calculated using the following formula: Conductor loss (W) = I 2 ×R I(A): Effective current value, R(Ω): Resistance value of the conductor

[0006] If the area available for heat dissipation based on this formula is kept constant, the heat generated by the conductor (coil) increases with increasing loss, meaning that in order to increase power, it becomes extremely important to reduce the resistance of the conductor (coil) and to facilitate the formation of the board joint (lead) as the conductor cross-sectional area increases. However, in Patent Document 1, after winding the rectangular wire around the one-piece iron core (including those with a case), it is necessary to perform some method of forming a board joint at the winding start, but no easy method is described.

[0007] Therefore, an object of the present technology is to provide a coil device that can easily accommodate higher power. [Means for solving the problem]

[0008] This technology is A four-sided frame A magnetic core, Insulated from the magnetic core, The magnetic core is laminated so that the faces that form the long sides of the cross section of the rectangular wire are stacked together. Each of the left and right sides of Wrapped around A first coil winding body and a second coil winding body are provided near the upper and lower sides of the magnetic core, and the ends of the first coil winding body and the second coil winding body are provided near the upper and lower sides of the magnetic core. A coil winding body of the above-mentioned It is a frame type consisting of four sides and an insulating separator in the center, and the first coil winding body and the second coil winding body are placed in the left and right openings. Coil winding body is placed A base part, The first coil winding body and the second coil winding body are provided at each corner of the base. Coil winding body Derived from Connected to the end A first connection terminal, a second connection terminal, a third connection terminal and a fourth connection terminalA connection terminal is provided. The ends of the winding termination sides led out from the first coil winding body and the second coil winding body are bent at approximately right angles so that their surfaces are approximately horizontal, the surfaces of the two opposing plate-shaped electrodes of the third connection terminal and the fourth connection terminal are approximately parallel to the surfaces of the bent ends of the winding termination sides, and the bent ends of the winding termination sides are disposed in the opposing gaps between the surfaces of the plate-shaped electrodes. It is a coil device. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of the appearance of a conventional common mode coil. [Diagram 2] FIG. 2 is an exploded perspective view of a conventional common mode coil. [Diagram 3] FIG. 3 is a perspective view of one embodiment of the present technology. [Figure 4] FIG. 4 is an exploded perspective view of one embodiment of the present technology. [Diagram 5] FIG. 5 is a perspective view of a modified example of an embodiment of the present technology. [Figure 6] FIG. 6 is an exploded perspective view of a modified example of an embodiment of the present technology. [Figure 7] FIG. 7 is a perspective view of a portion of a modified example of an embodiment of the present technology. [Figure 8] FIG. 8 is a perspective view for explaining the process of winding the electric wire. [Figure 9] FIG. 9 is a perspective view for explaining the assembly process. [Figure 10] FIG. 10 is a perspective view of the assembled coil device. [Figure 11] FIG. 11 is a front view of the coil device. [Figure 12] FIG. 12 is an enlarged perspective view of a portion of FIG. [Figure 13] FIG. 13 is an enlarged perspective view of a portion of FIG. [Figure 14] FIG. 14 is a perspective view used to explain a modified example of a connection terminal. [Figure 15] FIG. 15 is an enlarged perspective view used to explain a modified example of a connection terminal. [Figure 16] FIG. 16 is an enlarged perspective view used to explain a modified example of a connection terminal. [Figure 17] FIG. 17 is a partial perspective view of another embodiment of the present technology. [Figure 18] FIG. 18 is a schematic diagram used to explain the bending process of the winding start end portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present technology will be described with reference to the drawings. The embodiments described below are preferred specific examples of the present technology, and the content of the present technology is not limited to these embodiments.

[0011] Prior to describing this technology, a conventional toroidal type common mode coil will be described. Fig. 1 is an external perspective view of a conventional common mode coil, and Fig. 2 is an exploded perspective view thereof. A ring-shaped magnetic core 1 made of a magnetic material (iron core) mainly composed of Mn-Zn ferrite, amorphous iron, etc. is assembled into a lower case 2 made of resin and an upper case 3 made of resin.

[0012] An electric wire is wound around the lower case 2 and upper case 3 in which the ring-shaped magnetic core 1 is assembled, forming the coil windings 4a and 4b. The coil windings 4a and 4b are provided by winding an electric wire having a circular conductor cross section, generally called an enameled electric wire, with various insulating coatings applied to the surface. The lower case 2 and upper case 3 on which the coil windings 4a and 4b are mounted are assembled into a resin base 5.

[0013] 1, the position of the lead portion to be joined to the board is fixed by inserting the start and end ends of the coil winding body 4a into four holes 6 formed in the base 5. The conductor diameter and number of turns of the enameled electric wire used for the coil winding bodies 4a and 4b can be easily selected and adjusted according to the required electrical characteristics of the coil, the applied current value, the operating temperature environment, etc.

[0014] When attempting to increase power using this type of common mode coil structure and winding method, it is extremely important to reduce the resistance of the conductor (coil winding), as mentioned above. There are two methods available for reducing the resistance of this conductor. The first method is to reduce the resistance by reducing the number of turns and shortening the overall length of the conductor. However, this method also reduces the inductance value, which means that the electromagnetic filter performance of the common mode coil is reduced, creating a trade-off between loss reduction and filter performance.

[0015] The second method is to reduce resistance by thickening the wire diameter and increasing the conductor area, but as the wire diameter increases, the coil winding volume factor decreases and it becomes impossible to wind the specified number of turns, resulting in a similar relationship to the first method.In terms of productivity, the bending strength of the wire increases (it becomes more difficult to bend) as the wire diameter increases, making the work itself very hard, significantly reducing productivity, and in recent years it has also become very difficult to secure the necessary manpower, raising concerns about rising component costs.

[0016] For this reason, edgewise coil windings using rectangular wire that do not experience a significant drop in space factor even when the conductor area is expanded are used, and a proposal has been made to wind the rectangular wire edgewise and then stretch one end of it to form a board connection part. Edgewise winding is a winding method in which the edge side (short side of the cross section) of the rectangular wire is wound in a direction that is less likely to bend, and the surfaces that form the long side are laminated.

[0017] In terms of quality, the various insulating coating layers (thickness) added to the rectangular wire are themselves very thin, with a minimum thickness of 0.06 mm and a maximum thickness of 0.17 mm according to JIS C3215-01:2014. When this rectangular wire is wound into an edgewise coil, the insulating coating layer (thickness) on the inside (inner diameter of the coil winding) of the center of the long side of the rectangular wire shrinks, while the outer diameter (outer diameter of the coil winding) stretches. If it is forcibly stretched further from this state, it is easy to imagine that damage to the already stretched insulating coating layer (thickness) will increase, causing deterioration of the insulating performance, which may affect the long-term reliability (lifespan) of the parts.

[0018] For example, in the case of low-power edgewise coil windings, the current applied to the coil windings is small and there is no need to increase the conductor cross-sectional area, so it is within the range that can be handled manually (or mechanically). Therefore, the general joining method of terminal pin binding and soldering can be used for both ends of the coil windings. In contrast, for high-power applications, the conductor cross-sectional area is naturally enlarged to reduce the conductor resistance value in order to reduce losses, so the bending strength also increases and the soldering method by terminal pin binding described for low current applications cannot be used. Therefore, simply winding a rectangular wire edgewise does not allow the board joint formation work to be performed with long-term reliability (lifespan) in mind, and the work process cannot be improved.

[0019] An embodiment of the present technology solves the problems of the conventional coil winding device described above. Fig. 3 is an external perspective view of an embodiment of the present technology, and Fig. 4 is an exploded perspective view thereof. The two perspective views in Fig. 3 are perspective views seen from different directions. A magnetic core 11 in one embodiment is a frame type having four sides, and a first coil winding body 13a and a second coil winding body 13b are provided on a left side 12a and a right side 12b, respectively. The magnetic core 11 is an integral magnetic core without any divided or notched parts, and its surface is coated with an insulating coating.

[0020] The coil windings 13a and 13b are rectangular (copper) wires having various enamel insulation (coating) layers such as polyurethane. The coil winding 13a is formed by winding an electric wire from the upper side 12c to the lower side 12d of the left side 12a of the magnetic core 11 using a winding device. The coil winding 13b is formed by winding an electric wire from the upper side 12c to the lower side 12d of the right side 12b of the magnetic core 11 using a winding device. The electric wire is a rectangular wire with a rectangular cross section, and is wound (i.e., edgewise wound) so that the faces forming the long sides of the cross section are stacked on top of each other. In order to handle high power, the thickness (short side) of the conductor of the rectangular wire is 0.4 mm or more, and the width (long side) of the rectangular wire is three times the thickness or more.

[0021] Magnetic core 11, on which coil winding bodies 13a and 13b are provided, is supported by a resin base 14. Base 14 is a resin frame consisting of four sides 15a, 15b, 15c, and 15d on which magnetic core 11, around which first coil winding body 13a and second coil winding body 13b are wound, is placed, and an insulating separator 16 in the center. First and second coil winding bodies 13a and 13b are disposed in left and right openings 17a and 17b of base 14.

[0022] A first connection terminal 18, a second connection terminal 19, a third connection terminal 20, and a fourth connection terminal 21 are provided at each corner of the base part 14 by press-fitting or the like. These connection terminals 18-21 are made of metal such as copper, and the parts protruding from the upper surface of the base part 14 are parts to which the terminal lead parts of the electric wires are connected, and the parts protruding from the lower surface of the base part 14 are parts to which the board is connected. The winding end parts 22a and 22b of the coil winding bodies 13a and 13b, respectively, are bent at approximately right angles to the end faces.

[0023] 5, 6, and 7 show modified examples of an embodiment of the present technology. FIG. 5 is an external perspective view of the modified example, FIG. 6 is an exploded perspective view, and FIG. 7 is a perspective view showing a state in which the magnetic core 11 is enclosed by the upper case 31a and the lower case 31b. The two perspective views in FIG. 5 are perspective views seen from different directions. The magnetic core 11 is one without insulating coating. The upper cover 31a and the lower cover 31b are structured to secure a necessary creepage distance and to fit together. The difference from the configurations shown in FIG. 3 and FIG. 4 above is whether insulating coating or a resin cover is used to insulate the closed magnetic circuit magnetic core 11, which can be selected based on the safety standard requirements of various countries and the quality requirements of customers.

[0024] The manufacturing process of the coil device will be described using the resin cover described in Figures 5, 6, and 7 as an example. With the magnetic core 11 assembled into the upper cover 31a and the lower cover 31b (see Figure 7), as shown in Figure 8, a winding machine is used to push the rectangular wire in from the direction of the arrow, pass through a jig (not shown) that bends the rectangular wire, and draw a spiral along the circumferential surface of the resin cover consisting of the upper cover 31a and the lower cover 31b, to perform edgewise coil winding. As the winding machine, for example, the one described in JP 2017-130506 A can be used.

[0025] The electric wire of the coil winding body 13a is wound from the winding start end (starting end) 23a to the winding end end (terminal end) 22a, and the electric wire of the coil winding body 13b is wound from the winding start end (starting end) 23b to the winding end end (terminal end) 22b. When winding the electric wire on the left and right sides, it is possible to wind the electric wire on one side at a time, but in general, in consideration of productivity, the electric wire is wound on both sides at the same time. In this case, since the space during winding is not very wide, the winding start ends 23a and 23b do not protrude outside the outer periphery of the coil winding bodies 13a and 13b, or the protrusion amount is small.

[0026] Once the winding of the electric wire is complete, the next step in order to connect it to a circuit board is to either process both ends of the electric wire further to provide board connection (lead) parts that can be directly connected to the circuit board, or to solder the wire through connection terminals that are mainly made of copper and have been surface-treated (plated, etc.). Connection terminals are often used to ensure stable quality. This technology can be applied to either case.

[0027] As shown in FIG. 9, connection terminals 18, 19, 20, and 21 are press-fitted into the four corners of the resin base 14. The parts on which the coil windings 13a and 13b are provided are moved vertically along the insulating separator 16 provided at the center of the base 14 to be assembled. At this time, guide grooves are provided on the inner sides of the upper cover 31a and the lower cover 31b to ensure stable assembly, and the insulating separator 16 is assembled while sliding its side along the guide grooves. After assembly, work is performed to electrically connect the terminal lead parts of the coil windings to various connection terminals. In this way, the coil device according to the present technology as shown in FIG. 10 is completed. FIG. 10 is a perspective view of the coil device seen from a different direction. Also, FIG. 11 is a view taken along the CC arrow in FIG. 10.

[0028] The connection terminals 18 to 20 will now be described. The connection terminals 18 and 20 to which the winding start ends 23a and 23b are connected have the same structure, and the connection terminals 19 and 21 to which the winding end ends 22a and 22b are connected have the same structure. Fig. 12 shows an enlarged view of part A (connection terminal 20) in Fig. 10, and Fig. 13 shows an enlarged view of part B (connection terminal 19) in Fig. 10.

[0029] The connection terminal 20 is bent to have two surfaces (plate electrodes) that are approximately parallel to the surface of the electric wire (rectangular wire) of the winding start end 23b of the coil winding body 13b, and the tip of the winding start end 23b is inserted into the opposing gap (groove) between the two surfaces. The connection terminal 19 is bent into a U-shape to have two opposing surfaces (plate electrodes) that are approximately parallel to the surface of the winding end end 22a of the bent coil winding body 13a. The winding end end 22a of the coil winding body 13a is inserted into the inner surface of the back side of the two plate electrodes. Then, one of the two plate electrodes is bent so that the winding end end 22a is sandwiched by the connection terminal 19.

[0030] In this way, the winding start ends 23a and 23b of the coil winding bodies 13a and 13b are structured to fit into the grooves of the connection terminals 18 and 20, making it possible to form the board joint (lead) portion without bending the coil winding start portion again in the edgewise direction, and the winding end ends 22a and 22b are arranged to abut against the inner side of the rear terminal bent into a U-shape of the connection terminals 19 and 21. As a result, the winding end ends 22a and 22b are positioned so as to be horizontal with the connection fixing surface of the connection terminals 19 and 21. In other words, the winding end ends 22a and 22b are positioned so as to be vertical to the base portion 14. This makes it easy to bend the winding end ends 22a and 22b, and also makes it possible to perform flatwise bending that can be easily connected to the connection terminals.

[0031] Then, as shown in FIG. 13, the winding end 22a is sandwiched by the upper surface of the connection terminal 19, so that the rotational movement of the coil winding 13a is fixed, and in this state, each connection terminal is electrically joined by soldering or the like. When soldering is performed, by providing a through hole on the upper surface of the connection terminal, the soldering area between the winding start end and winding end end and the connection terminal can be enlarged, the mechanical joint strength can be improved, and the soldering workability can be improved. Note that instead of soldering, spot welding or the like may be used for joining. In this case, it is preferable to form a cylindrical or arc-shaped stamping so that the welding current flows concentratedly at the welding point, rather than a through hole in the terminal. Note that this series of operations is preferably performed automatically by equipment or the like.

[0032] 14, 15, and 16 show modified examples of the connection terminal in one embodiment of the present technology. In the configuration of Fig. 14 and Fig. 15, the connection terminals 19a and 21a, which are obtained by displacing the shape of the terminal lead portion clamping portion on the upper surface of the connection terminals 19 and 21 in the above-mentioned embodiment by 90°, are provided on the base portion 14. With such a configuration, the flatwise bending processability of the winding end ends 22a and 22b can be improved, which makes it possible to further facilitate automation using equipment, etc.

[0033] In the above explanation, the shape is described with the winding start end as the reference position, but the same productivity can be achieved by using the winding end as the reference position instead. However, when the winding end is used as the reference fixing position, as shown in Figure 16, a connection terminal 20a is used that is bent in the opposite direction to the connection terminal 20 (18). This increases the degree of freedom in the fixing position of the winding start end, and the accuracy of the bending position of the winding end end can be relaxed.

[0034] 17A and 17B are perspective views showing connection terminals according to another embodiment of the present technology. In the other embodiment, when the production volume is small, manual (hand) work can be performed with minimal burden on the worker. The process up to edgewise winding by the automatic winding machine is the same as that in the first embodiment, so a description thereof will be omitted. In the other embodiment, as shown in FIG. 17A, connection terminals 31, 32, 33, and 34 are provided at each corner of the base part 14. In the configuration shown in FIG. 17B, connection terminals 31a, 32a, 33a, and 34a are provided on the base part 14, with the shape of the terminal lead clamping part of these connection terminals displaced by 90°.

[0035] After edgewise winding, the winding start ends and winding ends of the coil winding bodies 13a and 13b are end The ends are bent at approximately right angles (flatwise bending) to be ready for connection to the connection terminals. The ends bent at approximately right angles to the end faces of the coil windings 13a and 13b are clamped by the clamping portions of the connection terminals 31 to 34 (or 31a to 34a). Then, similar to the embodiment described above, they are electrically joined by soldering or the like.

[0036] It is very important to apply flatwise bending to the flat wire wound in the respective annular coil windings 13a and 13b with the smallest load. Figure 18 shows a side view of the flat wire wound in an annular shape, and it can be seen that the length of the long side of the bent cross section increases when the bending position of the winding start end is changed from A (winding center position) to bending position B and bending position C. This means that, if the conductor thickness is unchanged, the area of ​​the bent cross section increases as the length of the long side of the bent cross section increases, and similarly, the load required for bending also increases, so bending is performed at the center position where the length of the long side of the bent cross section is the smallest.

[0037] On the other hand, because a straight portion remains at the end of the winding, in this case the required bending load does not change regardless of where the flatwise bending is performed, but if bending is performed beyond the straight portion at an annular position, the result will be the same as that at the beginning of the winding described above. Naturally, if the bending load is small, even in bending processing using automatic equipment, smaller equipment will suffice, making it possible to reduce equipment costs, etc.

[0038] The coil device according to the present technology described above provides the following effects. It is possible to realize inexpensive, high-power common mode windings. Longer life due to reduced damage to the insulating film layer Automating the work process reduces the number of workers required, which can lead to reduced parts costs. The number of workers can be significantly reduced. The cost of production equipment can be reduced.

[0039] Although one embodiment of the present technology has been specifically described above, the present technology is not limited to the above-described embodiment, and various modifications based on the technical ideas of the present technology are possible. Furthermore, the configurations, methods, steps, shapes, materials, and numerical values ​​given in the above-described embodiment are merely examples, and different configurations, methods, steps, shapes, materials, and numerical values ​​may be used as necessary. and numerical values ​​may also be used. [Explanation of symbols]

[0041] 11 magnetic core, 13a, 13b coil winding body, 14 base portion, 16: Insulating separator; 18, 19, 20, 21: Connection terminal; 22a, 22b... Winding end portion, 23a, 23b... Winding start end portion, 31a: Upper cover, 31b: Lower cover

Claims

1. A magnetic core having a frame shape with four sides, A first coil winding body and a second coil winding body are insulated from the magnetic core, are wound around the left and right sides of the magnetic core such that the surfaces forming the long sides of the cross section of the flat wire are stacked against each other, and have ends led out near the top and bottom sides of the magnetic core; a base portion having a frame shape with four sides and an insulating separator in the center, the first coil winding body and the second coil winding body being disposed in left and right openings; a first connection terminal, a second connection terminal, a third connection terminal and a fourth connection terminal provided at each corner of the base portion and connected to ends led out from the first coil winding body and the second coil winding body, A coil device in which the surfaces of the end portions of the winding termination sides derived from the first coil winding body and the second coil winding body are bent at approximately a right angle so that they are approximately horizontal, the surfaces of the two opposing plate-shaped electrodes of the third connection terminal and the fourth connection terminal are approximately parallel to the surfaces of the bent end portions of the winding termination sides, and the bent end portions of the winding termination sides are arranged in the opposing gaps between the surfaces of the plate-shaped electrodes.

2. 2. The coil device according to claim 1, wherein the thickness of the rectangular wire conductor is 0.4 mm or more, and the width of the rectangular wire is three times or more the thickness.

3. A coil device as described in claim 1 or 2, wherein the faces of the winding start side ends derived from the first coil winding body and the second coil winding body are bent at approximately a right angle so that they are approximately horizontal, the faces of the two opposing plate-shaped electrodes of the first connection terminal and the second connection terminal are approximately parallel to the faces of the bent winding start side ends, and the bent winding start side ends are arranged in the opposing gap between the faces of the plate-shaped electrodes.

4. 4. The coil device according to claim 3, wherein the bending positions of the winding start ends of the first coil winding body and the second coil winding body are located near the positions where the widths of the first coil winding body and the second coil winding body are at their minimum.

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