Coil device

Abstract

To provide a highly reliable coil device. [Solution] The coil device 100 comprises a wire 3, a bobbin 1 having a core 11 on which a winding portion 30 of the wire 3 is formed, a core 5 having outer legs 54, 56 arranged outside the winding portion 30, and a case 7 that houses at least a portion of the winding portion 30 and the outer legs 54, 56. At least a portion of the winding portion 30 and the outer legs 54, 56 inside the case 7 is sealed with a sealing material 9, and the core 11 of the bobbin 1 has a partition flange 20 that divides the winding portion 39 into multiple sections along the winding axis. The outermost tip 21 of the partition flange 20 is positioned closer to the core 11 than the outermost end 301a of the outermost layer 301 of the winding portion 30.

Description

[Technical Field]

[0001] The present invention relates to a coil device such as a transformer. [Background Art]

[0002] Patent Document 1 discloses an encased transformer. A transformer as disclosed in Patent Document 1 is expected to improve impact resistance, heat dissipation, and the like by sealing the inside of the case with resin. However, such a transformer may cause problems due to repeated use. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2014-36194 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] The present invention has been made in view of such circumstances, and an object of the present invention is to provide a highly reliable coil device. [Means for Solving the Problem]

[0005] As a result of intensive research, the inventor of the present invention has found that in the above-described transformer, heat generated in the coil causes the sealing material sealing the inside of the case to expand, and the force generated by the expansion acts on the core to cause the above-mentioned problems. According to the research of the inventor of the present invention, such problems can be solved by including low-expansion particles having a small linear thermal expansion coefficient in the sealing material disposed inside the outer leg portion. However, in order to fill such a sealing material inside the outer leg portion, increasing the gap between the outer leg portion and the wound portion inevitably results in an increase in size of the device. Accordingly, the inventor of the present invention has further conducted research and completed the present invention.

[0006] In other words, in order to achieve the above objective, the coil device according to the present invention is Wire and A bobbin having a winding core portion on which the winding portion of the wire is formed, A core having an outer leg portion disposed on the outside of the winding portion, It has a case that houses at least a part of the winding portion and the outer leg portion, At least a portion of the winding portion and the outer leg portion within the case is sealed with a sealing material. The winding core portion of the bobbin is formed with partition flanges that divide the winding portion into multiple sections along the winding axis. The outermost tip of the partition flange is positioned closer to the core than to the outermost end of the outermost layer of the winding portion.

[0007] This configuration creates gaps between the sections of the winding portion due to the partition flanges. These gaps allow for the reliable placement of a sealing material containing low-expansion particles with a small linear thermal expansion coefficient. Therefore, the sealing material placed inside the outer legs expands less than the sealing material placed outside the outer legs. Consequently, the coil device of the present invention improves the reliability of the coil's heat generation without increasing the size of the device.

[0008] Preferably, the protruding end of the partition flange is positioned further from the core than the inner end of the outermost layer of the winding portion. This configuration allows each section of the winding portion to be evenly distributed between the partition flanges without causing winding irregularities. By forming the winding portion in this way, the sealing material can be reliably positioned inside the outer leg portion.

[0009] Preferably, the thickness of the partition flange is equal to or greater than the width of the gap between the winding portion and the outer leg portion. This configuration makes it easier to position even sealing material containing large particles inside the outer leg portion.

[0010] Preferably, the partition flange portion has a plurality of notches, and the winding core portion has outer peripheral holes at positions corresponding to the notches. Through such outer peripheral holes, the sealing material can easily enter the through holes of the winding core portion, thereby more effectively improving the heat dissipation of the coil device.

[0011] Preferably, low-expansion particles, which have a lower coefficient of linear thermal expansion than the potting resin contained in the sealing material, are arranged in the gap between the partition flange and the outer leg along the circumferential direction of the winding portion. This configuration improves reliability against heat generation.

[0012] Preferably, the volume ratio of the potting resin in the gap between the partition flange and the outer leg is smaller than the volume ratio of the potting resin in the gap between the outer leg and the case.

[0013] In this way, the amount of potting resin that seeps into the gap between the partition flange and the outer leg can be reduced. The outer leg of the core is weak against forces applied from the inside to the outside, but by reducing the amount of potting resin in the gap between the winding portion and the outer leg, the force acting on the outer leg from the inside to the outside becomes less likely. Therefore, the reliability of the coil device in terms of heat generation is improved.

[0014] Furthermore, it is preferable to place potting resin in the gaps between the low-expansion particles in the gaps between the winding portion and the outer leg portion. By placing the potting resin in this manner, the heat generated in the coil can be efficiently dissipated. Even with the placement of the potting resin in this manner, the presence of low-expansion particles makes it difficult for the force due to the expansion of the potting resin to be transmitted to the outer leg portion, and thus does not affect the reliability of the coil device in terms of heat generation.

[0015] Preferably, the low-expansion particles are arranged in the gap between the winding portion and the outer leg portion, along the circumferential direction of the winding portion. This arrangement allows for a more effective reduction of the force directed from the inside outwards toward the outer leg portion.

[0016] Preferably, the low-expansion particles have a substantially spherical shape. Such low-expansion particles are easily arranged in the gap between the wound part and the outer leg part, and can efficiently reduce the amount of potting resin in the gap between the wound part and the outer leg part.

[0017] Preferably, the low-expansion particles include two or more types of particles with different particle diameters. With this configuration, the low-expansion particles can efficiently fill the gap between the wound part and the outer leg part.

[0018] Preferably, the sealing material is arranged at least in the gap between the outer leg part and the case. If the force applied from the outside to the inside to the outer leg part of the core decreases, the force applied from the inside to the outside will relatively act strongly on the outer leg part. By arranging the sealing material also in the gap between the outer leg part and the case in this way, the balance between the force applied from the inside acting on the outer leg part and the force applied from the outside can be maintained, and the durability of the outer leg part is improved. [BRIEF DESCRIPTION OF THE DRAWINGS]

[0019] [Figure 1] Figure 1 is an overall perspective view of a coil device according to an embodiment of the present invention. [Figure 2] Figure 2 is an exploded perspective view of the coil device shown in Figure 1. [Figure 3A] Figure 3A is a perspective view showing the configuration of the core of the coil device shown in Figure 1. [Figure 3B] Figure 3B is a perspective view showing another example of the core shown in Figure 3A. [Figure 3C] Figure 3C is a perspective view showing still another example of the core shown in Figure 3A. [Figure 4A] Figure 4A is a perspective view showing the configuration of the bobbin and the wires of the coil device shown in Figure 1. [Figure 4B] Figure 4B is a side view of the bobbin and the wires of the coil device shown in Figure 4A. [Figure 4C] Figure 4C is a plan view of the bobbin and the wires of the coil device shown in Figure 4A. [Figure 5]Figure 5 is a cross-sectional view along the VV line shown in Figure 1. [Figure 6A] Figure 6A is a cross-sectional view along the VIA-VIA line shown in Figure 1. [Figure 6B] Figure 6B is an enlarged view showing the configuration of the sealing material in the VIB portion shown in Figure 6A. [Figure 7] Figure 7 is a cross-sectional view taken along the line VII-VII shown in Figure 6A. [Modes for carrying out the invention]

[0020] Embodiments of the present invention will be described below with reference to the drawings. Note that the illustrations are for illustrative purposes only and illustrate the present invention; appearance and dimensional ratios may differ from the actual product. Furthermore, the present invention is not limited to the following embodiments.

[0021] (First Embodiment) The coil device 100 according to this embodiment, as shown in Figure 1, for example, has the function of a transformer and can be used as an on-board charger for EVs (Electric Vehicles), PHVs (Plug-in Hybrid Vehicles), or commuter vehicles, or as a power supply circuit for household or industrial electrical equipment, or as a power supply circuit for computer equipment, etc.

[0022] The size of the coil device 100 is not particularly limited, but for example, the length L0 in the X-axis direction may be 1 cm to 20 cm, the width W0 in the Y-axis direction may be 1 cm to 20 cm, and the height H0 in the Z-axis direction (see Figure 7) may be 1 cm to 20 cm.

[0023] In the drawings, the X-axis aligns with the coil winding axis C (see Figures 4B and 4C), and the X, Y, and Z axes are perpendicular to each other. In the following explanation, the Y-axis direction may be referred to as the width direction, and the Z-axis direction as the height direction. The side facing the center of the coil device 100 may be referred to as the inside or inward, and the side moving away from the center of the coil device 100 may be referred to as the outside or outward. The direction of the tip of the arrow indicating the Z-axis, relative to the orientation of the drawing, may be referred to as upward.

[0024] As shown in Figure 2, the coil device 100 generally comprises a bobbin 1, wires 3a and 3b, and a core 5. These are housed in a case 7, as shown in Figure 1, and a portion of the case is sealed with a sealing material (see Figure 6A, etc.). In this specification, wires 3a and 3b may be referred to as wire 3. The core 5 is made up of a combination of segmented cores 50_1, 50_2, 50_3, and 50_4, and in this specification, segmented cores 50_1, 50_2, 50_3, and 50_4 may be referred to as core 5.

[0025] The bobbin 1 is made up of an insulating material that insulates the wire 3 and the core 5. Examples of such insulating materials include plastics such as PPS, PET, PBT, and LCP.

[0026] Each of the wires 3 can be made of a known conductor. For example, they may be made of a known insulated wire in which the surface of a copper or other conductor is insulated with a polyimide film or the like. Each of the wires 3 may be made of a single wire or a twisted wire. The diameter of the wires 3 is preferably, for example, 1.0 to 3.0 mm. The diameters of the wires 3 may be the same or different.

[0027] As shown in Figure 2, the bobbin 1 generally has a winding core 11 extending along the X-axis and end flanges 14 and 16 at both ends of the winding core 11 in the X-axis direction. Wires 3a and 3b are wound around the winding core 11. The winding core 11 has a through hole 12 that penetrates in the X-axis direction. An outer peripheral hole 13 is formed in the winding core 11 that leads to the through hole 12. The middle leg portion 52 of the core 5 is inserted into the through hole 12.

[0028] As shown in Figure 4A, wire 3a has a winding portion 30a wound around the core of the bobbin 1 and lead portions 31a and 32a drawn out from the winding portion 30a. Wire 3b has a winding portion 30b wound around the core of the bobbin 1 and lead portions 31b and 32b drawn out from the winding portion 30b. In this specification, the winding portion 30a or the winding portion 30b may be simply referred to as the winding portion 30.

[0029] As shown in Figures 4B and 4C, the core portion 11 has a plurality of partition flanges 20 formed along the X-axis between the end flanges 14 and 16. The partition flanges 20 protrude outward in a direction perpendicular to the winding axis C and have a thickness of width W5 in the X-axis direction.

[0030] As shown in Figures 4B and 4C, the core portion 11 is divided into six sections along the X-axis direction by the partition flange portion 20. The winding portion 30a is located in the three sections closest to the end flange portion 14. The winding portion 30b is located in the three sections closest to the end flange portion 16. As shown in Figure 4C, a gap S5 with a width W5 is left between the outermost layers 301 in the outer circumference direction of adjacent sections of the winding portion 30, corresponding to the thickness of the partition flange portion in the X-axis direction.

[0031] In this embodiment, the winding portion 30 in each section is arranged so that there is one layer in the direction along the winding axis C (X-axis direction), but the number of layers in the X-axis direction is not particularly limited, and each section may have multiple layers arranged along the X-axis direction. Also, as shown in Figures 5 and 7, in this embodiment, the winding portion 30 in each section is wound so that there are three overlapping layers in the outer circumference direction perpendicular to the winding axis (direction perpendicular to the X-axis), but the number of layers in the outer circumference direction in each section is not particularly limited, and may be one layer, two layers, or four or more layers.

[0032] As shown in Figures 4B and 4C, the outermost tip 21 of the partition flange 20 is adjacent to the outermost layer 301 of the winding portion 30 in the outermost direction. The tip 21 is located closer to the winding core than the outermost end 301a of the outermost layer 301 in the outermost direction. That is, as shown in Figure 5, the distance D1 from the winding core 11 to the tip 21 of the partition flange 20 is shorter than the distance D2 from the winding core 11 to the outermost end 301a of the outermost layer 301. For example, the distance D1 is preferably about one-third to two-thirds shorter than the distance D2, and more preferably about half shorter than the diameter of the wire 3.

[0033] Distances D1 and D2 are not particularly limited, but from the viewpoint of preventing winding irregularities in the winding portion 30, it is preferable that the tip 21 is positioned further from the winding core than the inner end 301b of the outermost layer 301.

[0034] In this embodiment, a notch 22 is formed in the partition flange 20, except for the partition flange 20 located between the winding portion 30a and the winding portion 30b. The notch 22 extends from the tip 21 of the partition flange 20 to the winding core portion 11. The outer peripheral hole 13 of the winding core portion 11 is formed at a position corresponding to the notch 22 (see Figure 6A). Note that a notch may also be provided in the partition flange 20 located between the winding portion 30a and the winding portion 30b.

[0035] As shown in Figure 4A, lead grooves 151 and 152 are formed in the end flange portion 14 in the upward direction in the Z-axis direction. A lead portion 31a is positioned in lead groove 151. A lead portion 32a is positioned in lead groove 152. Lead grooves 151 and 152 each extend along the X-axis direction, and the lead portions 31a and 32a are drawn outward along the X-axis direction.

[0036] As shown in Figure 4A, lead grooves 171 and 172 are formed in the end flange portion 16 in the upward direction in the Z-axis direction. A lead portion 31b is positioned in lead groove 171. A lead portion 32b is positioned in lead groove 172. Lead grooves 171 and 172 each extend along the X-axis direction, and lead portions 31b and 32b are drawn outward along the X-axis direction.

[0037] As shown in Figure 4A, a mounting portion 173 is formed on the end flange portion 16, downward in the Z-axis direction. Similarly, a mounting portion 153 is formed on the end flange portion 14, downward in the Z-axis direction, symmetrical to the mounting portion 173 with respect to the YZ plane (see Figure 7). By placing the mounting portions 153 and 173 on the bottom surface 70 of the case 7 shown in Figure 7, the bobbin 1 can be stably mounted inside the case 7.

[0038] The material of core 5 shown in Figure 1 may include metals, ferrites, or other magnetic materials, but is not particularly limited. The segmented cores 50_1, 50_2, 50_3, and 50_4 that make up core 5 may each be made of similar materials, but do not necessarily have to be made of the same material.

[0039] As shown in Figure 3A, the divided core 50_1 has a base portion 58, a middle leg portion 52, and an outer leg portion 54. The middle leg portion 52 and the outer leg portion 54 of the divided core 50_1 protrude inward along the X axis from the inner surface 581 of the base portion 58.

[0040] As shown in Figure 5, the segmented core 50_1 is attached so that the inner surface 581 of the base portion 58 faces the end face 14a of the end flange portion 14 of the bobbin 1. The middle leg portion 52 of the segmented core 50_1 is inserted into the through hole 12 of the bobbin 1. The segmented core 50_1 is positioned outward in the Y-axis direction, with a gap S1 between the inner surface 541 of the outer leg portion 54 and the winding portion 30a. Sealing material 9 is placed in the gap S1 between the outer leg portion 54 and the winding portion 30a and in the gap S5 between the outermost layers 301 of each section of the winding portion 30a.

[0041] As shown in Figure 3A, the divided core 50_2 has a shape symmetric to that of the divided core 50_1 with respect to the XZ plane. The divided core 50_2 has a base portion 58, a middle leg portion 52, and an outer leg portion 56.

[0042] As shown in Figure 5, the segmented core 50_2 is attached so that the inner surface 581 of the base portion 58 faces the end face 14a of the end flange portion 14 of the bobbin 1. The middle leg portion 52 of the segmented core 50_2 is inserted into the through hole 12 of the bobbin 1. The segmented core 50_2 is positioned outward in the Y-axis direction with a gap S1 between the inner surface 561 of the outer leg portion 56 and the winding portion 30a. A sealing material 9 is placed in the gap S1 between the outer leg portion 56 and the winding portion 30a and in the gap S5 between the outermost layers 301 of each section of the winding portion 30a. The segmented core 50_1 and segmented core 50_2 are attached to the bobbin 1 with a gap between the segmented surfaces 60, but are not limited to this, and may be in contact with each other at the segmented surfaces 60.

[0043] As shown in Figure 3A, the divided core 50_3 has a shape symmetrical to the divided core 50_1 with respect to the YZ plane. The divided core 50_3 has a base portion 58, a middle leg portion 52, and an outer leg portion 54.

[0044] As shown in Figure 5, the segmented core 50_3 is attached so that the inner surface 581 of the base portion 58 faces the end face 16a of the end flange portion 16 of the bobbin 1. The middle leg portion 52 of the segmented core 50_3 is inserted into the through hole 12 of the bobbin 1. The segmented core 50_3 is positioned outward in the Y-axis direction, with a gap S1 between the inner surface 541 of the outer leg portion 54 and the winding portion 30b. Sealing material 9 is placed in the gap S1 between the outer leg portion 54 and the winding portion 30b and in the gap S5 between the outermost layers 301 of each section of the winding portion 30b.

[0045] As shown in Figure 3A, the segmented core 50_4 has a shape symmetric to that of segmented core 50_2 with respect to the YZ plane, and a shape symmetric to that of segmented core 50_3 with respect to the XZ plane. The segmented core 50_4 has a base portion 58, a middle leg portion 52, and an outer leg portion 56.

[0046] As shown in Figure 5, the segmented core 50_4 is attached to the bobbin 1 such that the inner surface 581 of the base portion 58 faces the end face 16a of the end flange portion 16. The middle leg portion 52 of the segmented core 50_4 is inserted into the through hole 12 of the bobbin 1. The segmented core 50_4 is positioned outward in the Y-axis direction with a gap S1 between the inner surface 561 of the outer leg portion 56 and the winding portion 30b. A sealing material 9 is placed in the gap S1 between the outer leg portion 56 and the winding portion 30b and in the gap S5 between the outermost layers 301 of each section of the winding portion 30b. The segmented cores 50_3 and 50_4 are attached to the bobbin 1 with a gap between the segmented surfaces 60, but are not limited to this, and may be in contact with each other at the segmented surfaces 60.

[0047] As shown in Figure 5, in this embodiment, the dividing surfaces 60 of the divided cores 50_3 and 50_4 are mounted in contact with the dividing surfaces 62 of the divided cores 50_1 and 50_2, but they may also be mounted on the bobbin 1 with a gap between them.

[0048] As shown in Figure 6A, the gap S1 between the outer leg portion 54 of the core 5 and the winding portion 30, and the gaps S5 between each section, are formed along the circumferential direction of the winding portion 30. The gap S1 between the outer leg portion 54 of the core 5 and the winding portion 30 is connected to the gap S4 between the bottom surface 70 of the case 7 in the lower Z-axis direction and the gap S1 between the outer leg portion 56 and the winding portion 30. The description of the gap S1 between the outer leg portion 54 of the core 5 and the winding portion 30, and the gaps S5 between each section, also applies to the gap S1 between the outer leg portion 56 and the winding portion 30, unless their properties differ.

[0049] As shown in Figure 5, the width W1 of the gap S1 between the outer leg portion 54 of the core 5 and the winding portion 30 is not particularly limited, but may be 1.0 mm to 2.0 mm. Also, the width W2 of the gap between the side surfaces 71, 72 of the case 7 and the outer surface 582 of the base portion 58 of the core 5 is preferably narrower than the width W1 of the gap S1, for example, it may be 0.3 mm to 0.6 mm. Also, the width W3 of the gap between the side surfaces 73, 74 of the case 7 and the outer surface 582 of the base portion 58 of the core 5 is preferably narrower than the width W1 of the gap S1, for example, it may be 0.3 mm to 0.6 mm.

[0050] As shown in Figure 5, the width W5 of the gap S5 between each section is not particularly limited, but it is preferably equal to or greater than the width W1 of the gap S1 between the outer leg portion 54 and the winding portion 30. For example, the width W5 may be 1.0 mm to 2.5 mm.

[0051] As shown in Figures 5, 6A, and 7, the bobbin 1, wire 3, and core 5 are housed in a case 7 and sealed with a sealing material 9. In this embodiment, the upper parts of the bobbin 1, wire 3, and core 5 are exposed from the sealing material 9, but they may be entirely covered with the sealing material 9 except for the lead portion. As shown in Figure 7, in this embodiment, the upper parts of the end flanges 14 and 16 of the bobbin 1 are exposed upward in the Z-axis direction from the case 7, making it easier to fill the case 7 with the sealing material 9.

[0052] As shown in Figures 5 and 6A, the sealing material 9 is placed in the gap S2 between the base portion 58 of the core and the side surfaces 71 and 72 of the case, and in the gap S3 between the outer legs 54 and 56 and the side surfaces 73 and 74. As shown in Figure 6A, the sealing material 9 is also placed in the gap S1 between the outer legs 54 and 56 of the core 5 and the winding portion 30, and in the gap S4 between the bottom surface 70 of the case 7 and the winding portion 30. As shown in Figures 5 and 6A, it is preferable that the sealing material 9 is also placed in the notch 22 of the partition flange portion 20.

[0053] In this embodiment, the sealing material 9 includes a potting resin 91. The potting resin 91 constituting the sealing material 9 is not particularly limited, and a known potting resin 91 can be used, provided that its linear thermal expansion coefficient is 20 × 10 -6 ~45×10 -6 Products with a temperature of / ℃ are preferably used.

[0054] The sealing material 9 may contain a known heat-dissipating filler. By including a heat-dissipating filler in the sealing material 9 in this way, the heat dissipation performance of the sealing material 9 is improved, making it possible to release the heat generated in the coil more efficiently.

[0055] As shown in Figure 6B, low-expansion particles 92, which have a lower coefficient of linear thermal expansion than the potting resin 91, are placed in gaps S1 and S5. Preferably, the potting resin 91 fills the gaps between the low-expansion particles 92. In this way, by placing low-expansion particles 92, which have a lower coefficient of linear thermal expansion than the potting resin 91, in gaps S1 and S5, the volume ratio of the potting resin 91 in the gaps (gaps S1 and S5) between the tip 21 of the partition flange 20 and the outer legs 54, 56 is smaller than the volume ratio of the potting resin 91 in gap S3 between the outer legs 54, 56 and the case 7. The volume ratio of the potting resin 91 in gaps S1 and S5 and in gap S3 are not particularly limited, but it is preferable that the volume ratio in gaps S1 and S5 be 80% or less of the volume ratio in gap S3, and more preferably 50% or less.

[0056] Low-expansion particles 92 are not particularly limited, and have a linear thermal expansion coefficient of 7.5 × 10⁻⁶ -6 Materials with a temperature of / ℃ or lower are preferably used, 7.2 × 10 -6 Particles with a temperature of / ℃ or lower are more preferably used. The shape of the low-expansion particles 92 is not particularly limited and may be approximately spherical or fibrous, but it is preferable that they be approximately spherical from the viewpoint of filling the gaps S1 and S5 well. Furthermore, from the viewpoint of ensuring insulation between the wound portion 30 and the outer leg portions 54, 56 in the gap S1, it is preferable that the low-expansion particles 92 are insulating.

[0057] The low-expansion particles 92 may include a ceramic material. For example, this ceramic material may consist of at least one substance selected from the group consisting of oxides, nitrides, and carbides. Alternatively, the ceramic material may consist of at least one substance selected from the group consisting of alumina, silicon nitride, aluminum nitride, and silicon carbide. Such substances are suitable for use as low-expansion particles 92 in the present invention because they also have excellent heat dissipation properties. In particular, alumina balls with a roughly spherical shape are preferably used as low-expansion particles 92.

[0058] The low-expansion particles 92 are smaller than the width W5 of the partition flange portion 20 and also smaller than the width W1 of the gap S1. Preferably, the low-expansion particles 92 are composed of multiple types of particles with different particle sizes. By composing the low-expansion particles 92 with multiple types of particles with different particle sizes, more low-expansion particles 92 can be placed in the gaps S1 and S5. For example, the low-expansion particles 92 may consist of first particles 92a with a particle size of 0.8 mm to 1.0 mm and second particles 92b with a particle size of 0.5 to 0.7 μm. Furthermore, the low-expansion particles 92 may also contain third particles with a particle size different from the first and second particles.

[0059] As described above, low-expansion particles 92 are placed in at least gaps S1 and S5, but as shown in Figure 5, it is preferable that the low-expansion particles 92 are also filled in gaps other than gaps S1 and S5, such as gap S4 between the bottom surface 70 of case 7 and winding portion 30 (see Figure 7), gaps between end flanges 14, 16 and winding portion 30, gaps between wires 3, and gaps between the inner surfaces 541, 561 of the outer leg portions 54, 56 and the winding core portion 11 of bobbin 1.

[0060] The coil device 100 according to this embodiment can be assembled, for example, as follows.

[0061] First, as shown in Figure 4A, wire 3 (3a, 3b) is wound onto bobbin 1. Next, cores 5 (50_1, 50_2, 50_3, 50_4) are attached to bobbin 1. Then, these are placed in case 7.

[0062] With the bobbin 1, wire 3 (3a, 3b), and core 5 (50_1, 50_2, 50_3, 50_4) housed in the case 7, low-expansion particles 92 are poured into the gaps S5 and S1 from above in the Z-axis direction. In this way, the low-expansion particles 92 fill the gap between the inner surfaces 541, 561 of the outer legs 54, 56 and the winding core portion 11 of the bobbin 1.

[0063] In this embodiment, the low-expansion particles 92 are smaller than the width W5 of the partition flange 20 and the width W1 of the gap S1, but it is preferable that the majority of the low-expansion particles 92 are larger than the width W2 of the gap S2 between the base portion 58 of the core 5 and the sides 71, 72 of the case. With this configuration, as shown in Figure 7, the low-expansion particles 92 fill the gap S4 between the winding portion 30 and the bottom surface 70 of the case 7, and the gap between the mounting portions 153, 173 of the bobbin 1 and the bottom surface 70, but are prevented from circulating to the outside of the base portion 58 of the core 5 through the gap S2. In addition, within the range that does not hinder the operation of this embodiment, the low-expansion particles 92 may have a particle size smaller than the width W2 of the gap S2.

[0064] Next, the sealing material 9 is poured into the case 7 from above in the Z-axis direction. In this way, the sealing material 9 fills the gaps that exist inside the case 7 (gaps S2, S3 between the core 5 and the case 7, gap S1, gaps between the end flanges 14, 16 and the winding portion 30, and gaps S5 between the wires 3, etc.).

[0065] As described above, in the coil device 100 according to this embodiment, at least a portion of the winding portion 30 and the outer leg portions 54, 56 are housed in the case 7, and at least a portion of the winding portion 30 and the outer leg portions 54, 56 inside the case 7 are sealed with a sealing material 9. As shown in Figure 5, in the sealing material 9, low-expansion particles are not placed in the gap S2 between the base portion 58 of the core and the side surfaces 71, 72 of the case, and in the gap S3 between the outer leg portions 54, 56 and the side surfaces 73, 74, but low-expansion particles 92 with a lower coefficient of linear thermal expansion than the potting resin 91 constituting the sealing material 9 are placed in at least the gap S5 between the outermost layers 301 of each section and in the gap S1 between the winding portion 30 and the outer leg portions 54, 56. Therefore, the volume ratio of the potting resin 91 inside the outer surfaces 541, 561 of the outer legs 54, 56 (the region including gaps S5 and S1) is smaller than the volume ratio of the potting resin 91 outside the outer surfaces 542, 562 of the outer legs 54, 56 (gap S3).

[0066] The outer legs 54 and 56 of the core 5 are weak against forces applied from the inside to the outside. However, in the gaps S5 between each section and the gap S1 between the winding section 30 and the outer legs 54 and 56, the volume ratio of the potting resin 91 is small, making it less susceptible to thermal expansion, and thus reducing the force acting on the outer legs 54 and 56 from the inside to the outside. In particular, in this embodiment, the gap S5 created by the partition flange 20 between each section makes it easier to reliably place the sealing material 9 containing low-expansion particles 92 with a small linear thermal expansion coefficient inside the outer legs 54 and 56. Therefore, the sealing material 9 placed inside the outer legs 54 and 56 expands less than the sealing material 9 placed outside the outer legs 54 and 56. Consequently, the coil device of the present invention can improve the reliability of the coil against heat generation without increasing the size of the device.

[0067] Furthermore, even without using expensive potting resin with a low coefficient of linear thermal expansion, the reliability against heat generation can be improved simply by pre-placing low-expansion particles 92 in gaps S5 and S1 and sealing them with inexpensive potting resin 91, thereby reducing the manufacturing cost of the coil device 100.

[0068] As described above, the sealing material 9 is also placed in the gap S3 between the outer legs 54, 56 and the sides 73, 74 of the case 7. If the force applied from the outside to the inside of the outer legs 54, 56 of the core 5 decreases, the force applied from the inside to the outside will relatively act strongly on the outer legs 54, 56. In this way, by placing the sealing material 9 in the gap S3 between the outer legs 54, 56 and the sides 73, 74 of the case 7, the balance between the forces applied from the inside and the forces applied from the outside acting on the outer legs 54, 56 can be maintained, and durability is improved.

[0069] In this embodiment, as described above, potting resin 91 is also placed in the gaps between the low-expansion particles 92. By placing the potting resin 91 in this manner, the sealing material 9 can efficiently dissipate the heat generated in the coil. Even with the potting resin 91 placed in this manner, the presence of the low-expansion particles 92 makes it difficult for the force due to the expansion of the potting resin 91 to be transmitted to the outer legs 54 and 56, and does not affect the reliability of the coil device 100 in terms of heat generation.

[0070] As shown in Figure 6A, in this embodiment, the low-expansion particles 92 are arranged along the circumferential direction of the winding portion 30 in the gaps S5 between each section and in the gaps S1 between the winding portion 30 and the outer leg portions 54, 56. This arrangement makes it possible to more effectively reduce the force directed from the inside outwards toward the outer leg portions 54, 56.

[0071] As shown in Figure 6B, the low-expansion particles 92 are approximately spherical in shape. Such low-expansion particles 92 are easily placed in the gap S1 between the winding portion 30 and the outer leg portions 54, 56, and can efficiently reduce the amount of potting resin 91 in the gap S1 between the winding portion 30 and the outer leg portions 54, 56.

[0072] As shown in Figure 6B, the low-expansion particles 92 include two or more types of particles 92a, 92b with different particle sizes. Furthermore, from the viewpoint of reducing the volume ratio of the potting resin 91 inside the outer surfaces 541, 561 of the outer legs 54, 56 (the region including the gap S1), it is preferable that the low-expansion particles 92 are densely packed in this region.

[0073] As shown in Figure 5, the tip 21 of the partition flange 20 is positioned further from the core 11 than the inner end 301b of the outermost layer 301. Therefore, each section of the winding portion 30 can be evenly arranged between the partition flanges 20 without causing winding irregularities. By forming the winding portion 30 in this way, the sealing material 9 can be reliably positioned inside the outer legs 54 and 56.

[0074] As shown in Figure 5, the thickness W5 of the partition flange 20 is equal to or greater than the width W1 of the gap S1 between the winding portion 30 and the outer legs 54, 56. Therefore, even if the sealing material 9 contains large particles 92a, it is easier to position it inside the outer legs 54, 56.

[0075] As shown in Figures 4B and 4C, the partition flange 20 has a plurality of notches 21. As shown in Figure 5, the winding core 11 has outer peripheral holes 13 at positions corresponding to the notches 21. The sealing material 9 can easily enter the through holes 12 of the winding core 11 through these outer peripheral holes 13, thereby more effectively improving the heat dissipation of the coil device 100.

[0076] (Second Embodiment) This embodiment has the same configuration as the first embodiment, except that the configuration of core 5a differs from that of core 5 in the first embodiment. The following describes the configuration of this embodiment, focusing primarily on the differences from the first embodiment.

[0077] In this embodiment, as shown in Figure 3B, the core 5a is formed by combining divided cores 50_5, 50_6, 50_7, and 50_8. Divided core 50_5 has a shape symmetrical to divided core 50_6 with respect to the XY plane. Divided cores 50_5 and 50_6 have a base portion 58, a middle leg portion 52, and outer leg portions 54 and 56.

[0078] As shown in Figure 3B, the segmented core 50_7 has a shape symmetric to that of segmented core 50_5 with respect to the YZ plane. The segmented core 50_8 has a shape symmetric to that of segmented core 50_6 with respect to the YZ plane and a shape symmetric to that of segmented core 50_7 with respect to the XY plane. The segmented cores 50_7 and 50_8 have a base portion 58, a middle leg portion 52, and outer leg portions 54 and 56.

[0079] In this embodiment, the same effects and advantages as in the first embodiment are achieved even with this configuration.

[0080] (Third embodiment) This embodiment has the same configuration as the first embodiment, except that the configuration of core 5b differs from that of core 5 in the first embodiment. The following describes the configuration of this embodiment, focusing primarily on the differences from the first embodiment.

[0081] In this embodiment, as shown in Figure 3C, the core 5b is formed by combining divided cores 50_9, 50_10, and 50_11. Divided core 50_9 has a shape symmetrical to divided core 50_10 with respect to the YZ plane. Divided cores 50_9 and 50_10 have a base portion 58 and outer leg portions 54 and 56. Divided core 50_11 is substantially cylindrical in shape.

[0082] For example, these can be assembled as follows: First, the segmented core 50_11 is placed inside the through hole 12 of the bobbin 1 shown in Figure 4A. Next, the segmented core 50_9 is attached to the end flange 14 such that the inner surface 581 of the base portion 58 abuts against the end face 64a of the segmented core 50_11. Next, the segmented core 50_10 is attached to the end flange 14 such that the inner surface 581 of the base portion 58 abuts against the end face 64b of the segmented core 50_11.

[0083] In this embodiment, the same effects and advantages as in the first embodiment are achieved even with this configuration.

[0084] Although the embodiments described above primarily illustrate applications to transformers, they may also be applied to coil devices other than transformers.

[0085] It should be noted that the present invention is not limited to the embodiments described above, and can be modified in various ways within the scope of the present invention. Furthermore, the configurations of each embodiment may be rearranged and applied as appropriate.

[0086] For example, the core portion 11 of the bobbin 1 may be placed vertically inside the case 7 so as to be aligned with the Z-axis direction. [Explanation of symbols]

[0087] 100... Coil device 1… Bobbin 11…Core section 12…Through hole 13…Outer hole 14...End flange 14a...end face 151, 152… Lead grooves 153... Mounting section 16...End flange 16a...end face 171, 172… Lead grooves 173... Mounting section 20... Partition flange 21…Tip 22... Notch 3(3a,3b)...Wire 30 (30a, 30b) ... winding section 301...Outermost layer 301a...outer end 301b…inner end 31a, 32a, 31b, 32b... Lead section 5, 5a, 5b... Cores 50_1, 50_2, 50_3, 50_4… Split cores 50_5, 50_6, 50_7, 50_8… Split cores 50_9, 50_10, 50_11… Split cores 52...middle leg 54,56...outer leg 541,561…inner 542,562…External surface 58...Base section 581...Inner self 582...External surface 60,62…divided plane 64a,64b…end face 7…cases 70...Bottom 71, 72, 73, 74… Side view 9… Sealing material 91...Potting resin 92…Low expansion particles 92a...first particle 92b…Second particle

Claims

1. Wire and A bobbin having a winding core portion on which the winding portion of the wire is formed, A core having an outer leg portion disposed on the outside of the winding portion, It has a case that houses at least a part of the winding portion and the outer leg portion, At least a portion of the winding portion and the outer leg portion within the case is sealed with a sealing material. The winding core portion of the bobbin is formed with partition flanges that divide the winding portion into multiple sections along the winding axis. The outermost protruding end of the partition flange is positioned closer to the core than to the outermost end of the outermost layer of the winding portion in this coil device.

2. The coil device according to claim 1, wherein the tip of the partition flange is positioned further from the core than the inner end of the outermost layer of the winding portion.

3. The coil device according to claim 1, wherein the thickness of the partition flange is equal to or greater than the width of the gap between the winding portion and the outer leg portion.

4. The partition flange portion has a plurality of notches, The coil device according to claim 1, wherein the winding core portion has an outer circumferential hole at a position corresponding to the notch.

5. The coil device according to claim 1, wherein low-expansion particles having a smaller coefficient of linear thermal expansion than the potting resin contained in the sealing material are arranged in the gap between the partition flange and the outer leg along the circumferential direction of the winding portion.

6. The coil device according to claim 5, wherein the volume ratio of the potting resin in the gap between the partition flange and the outer leg is smaller than the volume ratio of the potting resin in the gap between the outer leg and the case.

7. The coil device according to claim 5, wherein the low-expansion particles have a substantially spherical shape.

8. The coil device according to claim 5, wherein the low-expansion particles include two or more types of particles with different particle sizes.

9. The coil device according to claim 5, wherein the low-expansion particles include a ceramic material.

10. The coil device according to claim 1, wherein the sealing material includes a heat-dissipating filler.

11. The coil device according to claim 1, wherein the core comprises a plurality of segmented cores.

12. The aforementioned core is A base portion is positioned on one side of the winding portion in the axial direction, The coil device according to claim 1, further comprising a middle leg portion that protrudes from the base portion and is positioned inside the through hole of the bobbin.

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