Coil device

Abstract

Provided is a coil device comprising a plurality of terminals (5) for binding an end part (2a) of a coil wire (coil part) wound around a core part having a predetermined shape, the coil device including, in a portion of a region (5g) of the terminals (5) mounted on a predetermined mounting surface (electronic circuit board surface), a curved shape part (5c) that has a shape spaced away from the mounting surface and to which the end part (2a) of the coil wire (coil part) can be bound.　As a result, it is possible to obtain a coil device that can be reduced in size, especially in height, while improving vibration resistance.　The terminals are particularly effective when configured to be L-shaped terminals or gull-wing terminals.

Description

Coil device

[0001] The present invention relates to a coil device, and more particularly to a coil device provided with terminals for winding coil ends of a transformer device, a reactor device, etc. for vehicle use or the like.

[0002] In coil devices such as transformer devices and reactor devices, terminals for winding both ends of the coil are provided (see Cited Documents 1 and 2). As such terminals, for example, in the both-side edge regions at the bottom of the coil device, a plurality of L-shaped terminals or the like are linearly arranged, and the bottoms of these L-shaped terminals or the like are formed so as to be mounted on a substrate surface or the like. However, winding the coil ends around such L-shaped terminals or the like is done at the portion rising from the substrate surface or the like, and it becomes easy to receive stress due to vibration. Therefore, the vibration resistance of the coil device using L-shaped terminals or the like is not necessarily high. As a result, the winding of the coil wire has loosened or a disconnection has occurred.

[0003] On the other hand, a U-shaped terminal is known as a terminal that can improve the vibration resistance of the coil device. In this U-shaped terminal, the horizontal regions extending parallel to each other in the vertical direction are exposed from the resin portion of the device body, but the vertical region connecting these upper and lower horizontal regions is embedded in the resin portion of the device body. In this way, since the vertical region connecting the substrate surface mounting portion constituting the lower horizontal region of the terminal and the coil winding portion constituting the upper horizontal region of the terminal is embedded in the resin portion of the device body, vibration is difficult to be transmitted between the upper and lower horizontal regions, and it is possible to prevent the stress due to vibration from affecting the coil wire. Therefore, the vibration resistance of the coil device is improved.

[0004] JP-A-2010-140945 JP-A-2012-24856

[0005] As mentioned above, while using U-shaped terminals in a coil device improves its vibration resistance, it is necessary to ensure sufficient length of the vertical area embedded in the resin part of the device body to maintain strength. In addition, space is required to set up a horizontal area above the terminal as a tangle terminal (and to ensure sufficient insulation distance from the core, and distance so that the winding machine nozzle does not interfere with the mounting area), which increases the size of the coil device, making it particularly difficult to meet the demand for low-profile devices.

[0006] This invention has been made in view of the above circumstances, and aims to provide a coil device that can be miniaturized, particularly reduced in height, while improving vibration resistance.

[0007] The coil device of the present invention is a coil device comprising a plurality of terminals for entangling the ends of a coil wire wound around a core portion of a predetermined shape, characterized in that a portion of the area of ​​the terminals arranged along a predetermined mounting surface has a curved shape that is spaced apart from the mounting surface and is capable of entangling the ends of the coil wire.

[0008] Furthermore, in this coil device, it is desirable that the terminals are arranged along opposing sides of the coil device. It is also preferable that the terminals are L-shaped terminals or gull-wing terminals. Furthermore, it is preferable that the predetermined mounting surface is an electronic circuit board surface.

[0009] It is preferable that the hole formed between the curved portion and the predetermined mounting surface is sized such that one coil wire can pass through, but two cannot. In this case, it is preferable that the hole is sealed with solder while the ends of the coil wires are wrapped around the curved portion.

[0010] Furthermore, it is preferable that the curved portion is provided in the longitudinal middle portion of the area of ​​the terminal that is arranged along the predetermined mounting surface. The coil device of the present invention can be configured as a transformer device or a reactor device.

[0011] According to the coil device of the present invention, a portion of the area of ​​the terminal that is arranged along a predetermined mounting surface has a curved shape that is spaced apart from the mounting surface, and the coil wire is wrapped around this curved shape. This eliminates the need to wrap the ends of the coil wire at a position higher than the substrate surface, such as the portion of the terminal that rises from the substrate surface, as in conventional devices, thus reducing the effect of vibration-induced stress on the coil wire. Therefore, loosening of the coil wire wrapping and breakage of the wire can be prevented. Furthermore, since the coil wire wrapping portion can be arranged near the area that is mounted on the mounting surface, the length of the portion of the terminal that rises from the substrate surface can be shortened by the amount of the wrapping, thereby improving vibration resistance due to the lower profile and lower center of gravity of the device. In addition, since the terminal does not need to be U-shaped, the device can be made lower profile and smaller.

[0012] This is a perspective view showing the configuration of a coil device according to an embodiment of the present invention. This is a schematic diagram showing an enlarged view of some of the terminals of the coil device shown in Figure 1. This is a diagram showing the schematic shape of the terminals of the coil device shown in Figure 1. This is a cross-sectional view taken along line A-A' in Figure 2, showing the state in which the coil end is wrapped around the terminal of the coil device shown in Figure 1. This is a conceptual diagram showing a modified example of the terminals of the coil device according to an embodiment of the present invention. This is a diagram showing the stress distribution of some of the terminals of the coil device shown in Figure 1. This is a conceptual diagram showing a modified form of the terminals of the coil device according to an embodiment of the present invention. This is a perspective view showing the schematic configuration of a prior art coil device. This is a schematic diagram showing an enlarged view of some of the terminals of the coil device shown in Figure 8. This is a diagram showing the stress distribution of some of the terminals of the coil device shown in Figure 8.

[0013] Hereinafter, a coil device according to an embodiment of the present invention will be described with reference to the drawings. The coil device of this embodiment is applicable, for example, to an in-vehicle power conversion transformer device. Figure 1 is a perspective view of the coil device according to an embodiment of the present invention (hereinafter referred to as the transformer device 50) as seen from the front side at an oblique angle above, and Figure 2 is a perspective view showing an enlarged view of some of the terminals 5 of the transformer device 50 according to this embodiment.

[0014] As shown in Figure 1, the transformer device 50 comprises, as its main elements, a bobbin 1 with flanges at both ends of a hollow winding shaft (not shown), a coil section 2 in which primary and secondary windings are alternately wound around the winding shaft of the bobbin 1, and a pair of E-shaped magnetic cores 3 and 4 with central legs inserted from both sides into the hollow part of the winding shaft. Furthermore, as part of the bobbin 1, there are terminal blocks 1a and 1b positioned below the winding shaft and flanges, and terminals 5 extending laterally from the bottom of the terminal blocks 1a and 1b, for securing each end 2a of the coil section 2. Multiple terminals 5 are arranged in rows along the opposing sides of the terminal blocks 1a and 1b (four on each side in Figure 1), and each is soldered to the surface of a substrate (not shown: an electronic circuit board). As shown in Figure 2, Figure 3 which schematically shows the shape of the terminal, and Figure 4 which is a cross-sectional view taken along line A-A' in Figure 2, the terminal 5 consists of a substrate bonding portion 5g that is soldered to the substrate surface 8 (see Figure 4), and a vertical portion 5e that rises from the substrate bonding portion 5g and is embedded in the bottom of the terminal block 1a, and is roughly L-shaped.

[0015] The bobbin 1 is equipped with a winding shaft having a hollow hole around which the coiled wire is wound to form the coil portion 2. The winding shaft is provided with flanges on both sides and terminal blocks 1a and 1b below it. Considering moldability, mass production, micro-machining, electrical insulation, low cost, and mechanical strength, it is molded using an insulating resin such as 6,6-nylon.

[0016] In both of the magnetic cores 3 and 4, the central leg located in the middle of both outer legs (in Figure 1, the central legs of magnetic cores 3 and 4 are hidden by the coil portion 2 and are not visible) is inserted into the bobbin 1 through both openings of the hollow hole of the winding shaft, and the tips of the two central legs face each other with a predetermined distance (magnetic gap) between them inside the hollow hole. The tips of the opposing outer legs of magnetic cores 3 and 4 are arranged to be in contact with each other, as shown in Figure 1.

[0017] Furthermore, although the coil portion 2 is formed by winding a round wire, other shapes of coil wires, such as square wires, may also be used. Also, the coil portion 2 may be formed by sequentially stacking and winding a primary winding and a secondary winding, or by sequentially winding a primary winding and a secondary winding from one end to the other of the winding axis of the bobbin 1. Either the terminal 2a of the primary winding or the secondary winding is wound around the winding portion of each terminal 5. The terminals 5 are formed from a plate-shaped conductive material such as copper or aluminum.

[0018] As shown in Figure 2, the substrate bonding portion 5g comprises flat plate portions 5a and 5b arranged along the substrate, and an upwardly curved portion 5c provided between these flat plate portions 5a and 5b. Because the upwardly curved portion 5c is curved upward, a predetermined shaped hole 5d is formed between the metal member of the terminal 5 and the substrate surface 8 (see Figure 4) in this upwardly curved portion 5c. The end portion 2a of the coil portion 2 is passed through this hole 5d, and the end portion 2a is wrapped around it as shown in Figure 2.

[0019] In this embodiment, the terminal 5 is formed to be curved in the middle of the metal member of the terminal 5, so that the end portion 2a of the coil portion 2 can be wrapped around it without hindering mounting. On the other hand, as shown in Figure 3, the provision of this hole 5d reduces the mounting area between the terminal 5 and the substrate. To avoid this reduction to some extent, it is desirable that the hole 5d be as small as possible, and if there is no problem with the function of wrapping around the end portion 2a of the coil portion 2, it is preferable that the size of the hole 5d be large enough for one to two wires constituting the coil portion 2 to pass through, more preferably large enough for one wire to pass through but not two. It is preferable that this hole 5d be filled with solder after the end portion 2a of the coil portion 2 is wrapped around it, thereby mitigating the reduction in the mounting area between the terminal 5 and the substrate surface 8.

[0020] Furthermore, Figure 4 shows a cross-sectional view along line A-A' in Figure 2, and is particularly intended to explain the effects of the L-shaped terminal 5. Specifically, as described above, the terminal 5 consists of a substrate joint portion 5g arranged along the substrate surface 8 and a vertical portion 5e that rises from the substrate joint portion 5g and is embedded in the terminal block 1a. An upwardly curved portion 5c is provided between the flat plate portions 5a and 5b of the substrate joint portion 5g, and the end portion 2a of the coil portion 2 is wrapped around this upwardly curved portion 5c.

[0021] On the other hand, the terminal 105 of the conventional transformer device 150 shown in Figure 8 consists of a substrate bonding portion 105a that is bonded to the substrate surface and a vertical portion 105e that rises from the substrate bonding portion 105a and is embedded in the bottom of the terminal block 101a, and is roughly L-shaped, but as shown in Figure 9, the end 102a of the coil portion 102 is wrapped around the vertical portion 105e. Note that for the components constituting the conventional transformer device 150, those corresponding to the components constituting the transformer device 50 according to this embodiment are indicated by adding 100 to the reference numeral of the component constituting the transformer device 50 according to this embodiment.

[0022] As described above, in the conventional transformer device 150, the end 102a of the coil section 102 is wrapped around the upright section 105e, as shown in Figure 9. However, in the transformer device 50 of this embodiment, the end 2a of the coil section 2 does not need to be wrapped around the upright section 5e. Therefore, the length of the upright section 5e can be shortened by the length of the wrapping allowance, and the transformer device 50 can be made lower in profile. Furthermore, by making it lower in profile, the center of gravity of the transformer device 50 can be lowered, and vibration resistance can be improved.

[0023] Furthermore, as mentioned above, in the upward curved portion 5c, a predetermined shaped hole 5d is formed between the terminal 5 and the substrate surface 8, and the end portion 2a of the coil portion 2 is passed through it as shown in the figure. Solder is filled into the gap of this hole 5d, making it possible to mount the upper curved portion 5c area onto the substrate surface 8, thereby suppressing a reduction in the mounting area. This helps to stabilize the device.

[0024] Furthermore, in the transformer device 50 of this embodiment, the upward curved portion 5c where the end 2a of the coil portion 2 is entangled is positioned away from resin parts such as the terminal block 1a and flanges provided on the bobbin 2. Therefore, even when the coating on the entangled portion is removed by heat treatment such as a laser, there is little risk of thermal damage to the resin parts.

[0025] Furthermore, even when the soldering of the entangled portion of the end 2a of the coil portion 2 is performed by immersion soldering (solder dip), it can be done at a position away from the resin portion as described above. Therefore, even when the entangled portion is immersed in high-temperature solder, it becomes easier to form the resin portion from thermoplastic resin. In addition, since the entanglement of the end 102a of the coil portion 102 is performed at a position away from the base of the terminal 5, where burrs are likely to occur during molding, the risk of poor solder connection of the coil wire due to burrs can be avoided.

[0026] As described above, the terminal 5 of the transformer device 50 in this embodiment is L-shaped, but instead of the L-shape, it is possible to make the terminal 15 a gull-wing type, as shown in the coil device 50a in Figure 5. That is, in this coil device 50a, the terminal 15 installed on the side of the device body 10 is of the gull-wing type, and an upward curved portion 15c is formed in the middle of the substrate joint portion 15g arranged along the substrate surface, which wraps around the end of the coil portion.

[0027] Thus, even when the terminal 15 is of the gull-wing type, an upwardly curved portion 15c can be provided on the substrate bonding portion 15g arranged along the substrate surface, and a tangled portion can be formed near the substrate surface. This eliminates the need to provide a tangled portion on other parts of the terminal 15, contributing to a lower profile, miniaturization, and improved vibration resistance of the coil device.

[0028] Figure 6 shows the stress distribution when a predetermined vibration is applied to the terminal 5 of the transformer device 50 of this embodiment. In Figure 6, this stress distribution is displayed in five levels of concentration, as shown in the lower right of the page, with higher concentrations indicating greater stress (MPa). Specifically, in the five-level concentration notation in Figure 6, from the bottom up, the levels are: Level 1: 0.0 or more to less than 3.4 (MPa); Level 2: 3.4 or more to less than 6.8 (MPa); Level 3: 6.8 or more to less than 10.2 (MPa); Level 4: 10.2 or more to less than 13.6 (MPa); and Level 5: 13.6 or more to 17.0 (MPa). The higher the concentration, the greater the stress level.

[0029] As shown in Figure 6, the stress distribution at the terminal 5 of the transformer device 50 in this embodiment shows that while there is a stress level of approximately 1 to 3 at the bent portion 5f between the substrate joint portion 5g and the upright portion 5e, there is almost no stress at approximately level 1 at the upward curved portion 5c between the flat portions 5a and 5b. This significantly reduces the stress due to vibration applied to the end portion 2a of the coil portion 2 that is wrapped around this upward curved portion 5c, thereby preventing loosening of the coil wires and preventing breakage.

[0030] On the other hand, Figure 10 shows the stress distribution when analyzing a predetermined vibration applied to the terminal 105 of the conventional transformer device 150 shown in Figures 8 and 9 (equivalent to the predetermined vibration applied to the terminal 5 of the transformer device 50 according to this embodiment). In Figure 10, this stress distribution is also shown in the same five-level display as in Figure 6 (displayed in the lower right of Figure 10). As shown in Figure 10, the stress distribution at the terminal 105 of the conventional transformer device 150 shows that a stress of level 3 to 5 is applied to the bent portion 105f between the substrate joint portion 105g and the upright portion 105e, and a stress of level 2 to 3 is also applied to the upright portion 105e to which the end portion 102a of the coil 102 is wrapped. Therefore, the stress due to vibration affects the coil wire wrapped around the upright portion 105e, increasing the possibility of loosening of the coil wire or breakage.

[0031] As explained above using Figures 6 and 10, the transformer device 50 according to this embodiment can significantly reduce the stress applied to the tangled portion of the coil wires compared to the conventional transformer device 150, thereby significantly reducing the frequency of loosening of the coil wire entanglement and breakage.

[0032] (Modified Embodiments) The coil device of the present invention is not limited to the embodiment described above, and various other embodiments can be applied. For example, in the embodiment described above, one upward curved portion 5c is provided for each terminal 5, but it is possible to provide two or more upward curved portions 5c for each terminal 5. Also, the upward curved portion 5c may be provided at any position on the substrate bonding portion 5g, but it is preferable to provide it in the middle portion, and more specifically, it is preferable to provide it in a position closer to the tip of the substrate bonding portion 5g than in the middle portion closer to the bent portion 5f.

[0033] Furthermore, in the above embodiment, the terminals are arranged along two opposing sides of the transformer body, but they may be arranged along either one, three, or four sides. Also, in the above embodiment, a pair of E-shaped cores are combined as the magnetic core, but other shapes of magnetic cores, such as a pair of U-shaped cores or a pair of PQ-shaped cores, can also be used.

[0034] Furthermore, in the transformer devices 50 and 50a of the above-described embodiments, the terminals 5 and 5a of the transformer devices 50 and 50a are L-shaped or gull-wing type. However, instead of such shapes, it is also possible to use flat-lead type terminals, as shown in the transformer device 50b in Figure 7. Specifically, in this transformer device 50b, the terminals 25 installed on the side of the device body 20 are of the flat-lead type, and an upwardly curved portion 25c is formed in the middle of the substrate joint portion 25g arranged along the substrate surface, which wraps around the end of the coil portion.

[0035] Since the flat lead type terminal 25 does not have an upright portion rising from the substrate joint, conventionally the end of the coil portion has been wrapped around a part other than the terminal. However, compared to such conventional techniques, forming an upward curved portion 25c in the middle of the substrate joint to wrap around the end of the coil portion makes it possible to contribute to miniaturization of the device and improvement of vibration resistance.

[0036] Furthermore, although the coil device in the above-described embodiment is a transformer device, the coil device of the present invention can be applied to reactor devices and the like in addition to transformer devices. Note that the transformer device in the above embodiment does not have a cover, but it is also possible to provide a device with a cover on the upper part of the transformer device 50 shown in Figure 1.

[0037] 1, 101 Bobbin 1a, 1b, 101a, 101b Terminal block 2, 102 Coil section 2a, 102a End section 3, 4, 103, 104 Magnetic core 5, 15, 25, 105 Terminals 5a, 5b Flat section 5c, 15c, 25c Upward curved section 5d Hole section 5e, 105e Upright section 5f, 105f Bent section 5g, 15g, 105a Substrate bonding section 8 Substrate surface 10, 20 Device body 50, 50a, 50b, 150 Transformer device

Claims

1. A coil device comprising a plurality of terminals for entangling the ends of a coil wire wound around a core of a predetermined shape, characterized in that a portion of the area of ​​the terminals arranged along a predetermined mounting surface has a curved shape that is spaced apart from the mounting surface and capable of entangling the ends of the coil wire.

2. The coil device according to claim 1, characterized in that the terminals are arranged along opposing sides of the coil device.

3. The coil device according to claim 1, characterized in that the terminal is an L-shaped terminal or a gull-wing terminal.

4. The coil device according to claim 1, characterized in that the predetermined mounting surface is an electronic circuit board surface.

5. The coil device according to claim 1, characterized in that the hole formed between the curved portion and the predetermined mounting surface is sized such that one coil wire can pass through, but two wires cannot.

6. The coil device according to claim 5, characterized in that the end of the coil wire is wrapped around the curved portion and the hole is sealed with solder.

7. The coil device according to claim 1, characterized in that the curved portion is provided in the longitudinal middle portion of the area of ​​the terminal that is arranged along the predetermined mounting surface.

8. The coil device according to any one of claims 1 to 7, characterized in that it is configured as a transformer device or a reactor device.

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