Magnetic core unit, and noise filter using the same

Abstract

To provide a magnetic unit which can suppress reduction in magnetic characteristics due to a stress caused by shrinkage in curing of an adhesive used in fixation of a magnetic core while surely obtaining a fixation force of the magnetic core in a case, and a noise filter using the same.SOLUTION: A magnetic core unit has: a resin case that is formed by combining a plurality of case members 10 and 20 and has a plurality of annular space parts arranged in the same axial line direction; and annular magnetic cores 5 stored in each of the annular space parts of the resin case, in which each of the case members has a plurality of projections 71 projecting in the axial line direction in the annular space parts. The annular magnetic cores are wound bodies around which an Fe group amorphous alloy strip or an Fe group nanocrystal alloy strip is around, and that has an end face facing an inner periphery and an outer periphery, the annular magnetic cores and the resin case are bonded and fixed to each other so that a surface where the projections of the case member are formed and the end faces of the annular magnetic cores face each other, and a through hole is provided on the inner peripheral side of the annular magnetic cores.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a magnetic core unit having a plurality of annular magnetic cores covered with a resin case, and to a noise filter such as a choke coil using the same. [Background technology]

[0002] Busbars (thick copper rods) are used in paths where relatively large currents exceeding 100A flow, such as between the onboard charging circuit and external power source in hybrid or electric vehicles, or between an AC motor and power supply circuit. Because the current flowing through the busbar can generate noise, a noise filter is often constructed by placing a magnetic core in the current path and passing the busbar through it, taking into consideration its impact on surrounding electronic devices. Such noise filters use a magnetic core unit in which the magnetic core is covered with a resin material to insulate the busbar from the magnetic core or other components.

[0003] While magnetic core units come in a variety of forms, Patent Document 1 discloses a noise filter with a core case structure in which annular magnetic cores are stacked coaxially. As shown in FIG. 17, the noise filter comprises a resin case consisting of an upper core case 510, a lower core case 530, an intermediate core case 520, and a connecting member 700, and multiple magnetic cores 610, 620 housed in an annular storage section formed in the resin case. Slit grooves are formed on the inner periphery of the upper core case 510 and the lower core case 530, into which a connecting member 700 is fitted to connect them together with the intermediate core case 520, forming a core case structure in which the magnetic cores 610, 620 are housed in the annular storage section. The depth of the annular storage section corresponds to the thickness of the magnetic cores 610, 620, and the magnetic cores 610, 620 are sandwiched between the upper core case 510, the lower core case 530, and the intermediate core case 520 to secure the entire structure. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2017-152549 Summary of the Invention [Problem to be solved by the invention]

[0005] In paths through which relatively large currents flow, metal-based magnetic materials with higher saturation magnetic flux densities than ferrite are selected as the magnetic material for the magnetic core used in noise filters. For example, Fe-based amorphous alloys and Fe-based nanocrystalline alloys are often used. Noise filters using annular magnetic cores formed by winding a ribbon of Fe-based amorphous alloy or Fe-based nanocrystalline alloy (hereinafter sometimes referred to as alloy ribbon) into a ring shape tend to achieve high impedance over a wide frequency range from several kHz to several MHz, and are suitable for preventing malfunction of on-board electronic devices due to noise in automobiles that employ vehicle control systems that communicate data between multiple electronic control devices via an on-board local area network (LAN).

[0006] On the other hand, magnetic materials such as Fe-based amorphous alloys and Fe-based nanocrystalline alloys have characteristics such as large magnetostriction, sensitivity to shock and stress, and brittleness in their ribbons. Therefore, when using a core case to hold down the magnetic core in the annular storage compartment, as in conventional noise filters, this can lead to degradation of magnetic properties, such as increased coercivity and decreased magnetic permeability. Furthermore, if the holding force is insufficient, the magnetic core may move within the annular storage compartment and collide with the core case, potentially damaging the magnetic core itself.

[0007] Therefore, the core case and the magnetic core are adhesively fixed to each other by making the annular housing portion approximately the same thickness as or thicker than the magnetic core. However, even when the magnetic core is fixed by adhesive, stress is applied to the magnetic core due to shrinkage caused by hardening of the adhesive, and the problem of deterioration of magnetic properties remains, although to varying degrees. As will be described in more detail later, this problem can be particularly pronounced in structures using multiple magnetic cores, such as the conventional noise filter shown in Patent Document 1.

[0008] Therefore, the present invention aims to provide a magnetic core unit that can securely fix the magnetic core within the case using an adhesive while suppressing the deterioration of magnetic properties due to stress caused by shrinkage when the adhesive hardens, and a noise filter using the same. [Means for solving the problem]

[0009] The first invention is a magnetic core unit comprising: a resin case formed by combining a plurality of case members and having a plurality of annular spaces arranged in the same axial direction; and annular magnetic cores housed in each of the annular spaces of the resin case; each of the case members has a plurality of protrusions protruding in the axial direction in the annular spaces; the annular magnetic cores are wound with an Fe-based amorphous alloy ribbon or an Fe-based nanocrystalline alloy ribbon and have end faces facing the inner and outer circumferences; the annular magnetic cores and the resin case are adhesively fixed together so that the surface of the case member on which the protrusions are formed faces the end faces of the annular magnetic cores; and at least two of the annular magnetic cores are arranged side by side.

[0010] In the magnetic core unit of the present invention, it is preferable that a through hole is formed on the inner peripheral side of the annular magnetic core, and that the through hole is partitioned in the axial direction by partition portions formed by a plurality of case members.

[0011] In the magnetic core unit of the present invention, it is preferable that the resin case includes a first case member and a second case member, each of which has a groove-shaped opening in cross section cut in the axial direction, the first case member having one groove-shaped opening that opens in the axial direction, and the second case member having two groove-shaped openings that open in the axial direction and in opposite directions to each other, and that two of the first case members are combined with the second case member, and the groove-shaped openings of the first case member and the second case member are combined to form two annular accommodating sections.

[0012] In the magnetic core unit of the present invention, it is preferable that both end sides of the resin case in the axial direction have honeycomb structure portions.

[0013] A second invention is a noise filter comprising the magnetic core unit of the first invention and a plurality of bus bars, in which the bus bars are passed through through holes in the magnetic core unit. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a magnetic core unit that can secure the magnetic core within the case using an adhesive while suppressing the deterioration of magnetic properties due to stress caused by shrinkage when the adhesive hardens, and a noise filter using the same. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view of a core unit according to an embodiment of the present invention. [Figure 2] FIG. 2 is an exploded perspective view of the core unit shown in FIG. [Figure 3] FIG. 2 is a perspective view of a noise filter using the magnetic core unit shown in FIG. [Figure 4] FIG. 2 is a front view of a first case member used in the magnetic core unit according to one embodiment of the present invention. [Figure 5] 5 is a partial cross-sectional view taken along line bb' of the underside of the first case member shown in FIG. 4. FIG. [Figure 6] FIG. 5 is a rear view of the first case member shown in FIG. [Figure 7] 5 is a partial cross-sectional view of the right side of the first case member taken along line bb' in FIG. 4. FIG. [Figure 8] 8 is an enlarged view of a portion A of the first case member shown in FIG. 7. FIG. [Figure 9] FIG. 3 is a front view of a second case member used in the magnetic core unit according to one embodiment of the present invention. [Figure 10] 10 is a partial cross-sectional view taken along line cc' of the underside of the second case member shown in FIG. 9. FIG. [Figure 11] 10 is a partial cross-sectional view taken along line cc' of the right side of the second case member shown in FIG. 9. FIG. [Figure 12]12 is an enlarged view of a portion B of the second case member shown in FIG. [Figure 13] 1 is a perspective view of an annular core used in a core unit according to an embodiment of the present invention. [Figure 14] FIG. 2 is a front view of a core unit according to an embodiment of the present invention. [Figure 15] 15 is a partial cross-sectional view taken along line aa' of the bottom surface of the magnetic core unit shown in FIG. 14. FIG. [Figure 16] 15 is a partial cross-sectional view taken along line aa' on the right side of the core unit shown in FIG. 14. FIG. [Figure 17] FIG. 10 is an exploded perspective view of a conventional noise filter. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to these. In this specification, when describing a structure, a relative positional relationship may be described by referring to one direction as "upper" and the opposite direction as "lower," but this does not indicate a common positional relationship or direction between the drawings. In addition, in some or all of the drawings, structural parts that are not necessary for the description are omitted, and some parts are illustrated enlarged for ease of explanation. Unless otherwise specified, the shapes and other features shown in the description are not limited to those described and illustrated in the drawings. Furthermore, in the description, the same names and symbols indicate identical or similar components, and detailed descriptions may be omitted even if they are illustrated.

[0017] FIG. 1 is a perspective view showing one embodiment of a core unit, and FIG. 2 is an exploded perspective view thereof. As shown in the figure, the core unit 1 of this embodiment has an oval cylindrical shape with a flat surface facing the z-axis direction and a curved surface facing the x-axis direction on its side. By arranging the flat surface of the core unit 1 so that it faces the xy plane, a noise filter with a low profile in the z-axis direction can be achieved. Two first case members 10 are arranged in the y-axis direction of the core unit 1, and a second case member 20 is disposed between the first case members 10. Each of the first case member 10 and the second case member 20 is formed from a resin material using a known method such as injection molding. In the illustrated example, the first case members 10 located on both ends of the core unit 1 have the same structure, but they may be different.

[0018] Annular magnetic cores 5 are arranged on both sides of the second case member 20 in the y-axis direction. As will be described in detail later, the annular magnetic cores 5 are housed in an annular space formed by combining the first case member 10 and the second case member 20, and are bonded and fixed to the first case member 10 and the second case member 20 with an adhesive. The first case member 10 and the second case member 20 are structured to have protrusions that protrude inward in the annular spaces.

[0019] The wider the alloy ribbon that makes up the toroidal core 5, the greater the waviness, and the space factor of a magnetic core using such an alloy ribbon tends to decrease. It is known that a decrease in space factor affects the impedance characteristics of a noise filter. Therefore, the magnetic core unit of this embodiment uses multiple toroidal cores 5 made of alloy ribbons with small waviness obtained by cutting a wide alloy ribbon, thereby ensuring the cross-sectional area of the magnetic path and preventing a decrease in the space factor of the magnetic core, and preventing deterioration of noise filter characteristics, such as an inability to obtain high impedance at a specified frequency.

[0020] In the magnetic core unit 1 formed by combining the various components, the annular space is closed by the first case member 10 and the second case member 20, and the annular magnetic core 5 housed in the annular space is not visible from the outside. Both ends of the magnetic core unit 1 in the y-axis direction form a honeycomb structure portion 110 formed as an assembly of a row of multiple bottomed holes 111, 112 formed in the first case member 10. Here, the shape of the holes in the honeycomb structure is not limited to a hexagonal shape. Furthermore, in the magnetic core unit 1, two through holes 131, 132 are formed on the inner circumferential side of the annular magnetic core 5, separated by a partition portion 141, through which a bus bar passes.

[0021] FIG. 3 is an external perspective view of a noise filter according to one embodiment of the present invention. The noise filter includes a magnetic core unit 1 and bus bars 101 and 102. The bus bars 101 and 102 are passed through through holes 131 and 132, respectively, separated by a partition 141 in the magnetic core unit 1, with their surfaces facing in the same direction. The through holes 131 and 132 in the magnetic core unit 1 allow the bus bars 101 and 102 to be easily positioned and arranged. Furthermore, the spatial distance between the bus bars 101 and 102 is determined by the partition 141, making it easy to ensure electrical insulation. Furthermore, the annular magnetic core 5 is disposed in the annular space enclosed by the first case member 10 and the second case member 20, making it easy to ensure electrical insulation between the bus bars 101 and 102 and the annular magnetic core 5.

[0022] In the illustrated noise filter, both ends of bus bars 101, 102 are aligned at equal intervals and extend linearly. The shape of bus bars 101, 102 is not limited to this, and they can be modified into various shapes as long as they can pass through through holes 131, 132 of magnetic core unit 1. For example, the ends of bus bars 101, 102 may be bent, for example, formed into an L-shape, so that the distance between bus bars 101, 102 is wider on at least one end side of magnetic core unit 1.

[0023] The space in which a noise filter is placed is often limited, so there is always a demand for compact noise filters. When attempting to make a noise filter compact, the magnetic core unit 1 and the bus bars 101, 102 naturally come close to each other. When a large current flows through the bus bars 101, 102, the bus bars generate heat due to copper loss caused by resistance, and reach high temperatures. This also makes it easy for the magnetic core unit 1, which is close to the bus bars 101, 102, to reach high temperatures. If the magnetic core unit 1 becomes extremely hot, the first case member 10 and the second case member 20 may be thermally damaged. Furthermore, the case members 10 and 20, the annular magnetic core 5, and the adhesive that secures them all have different linear expansion coefficients. This difference in linear expansion coefficients causes dimensional changes with temperature, which can change the stress applied to the annular magnetic core 5 and degrade its magnetic properties. Furthermore, the adhesive fixation of the annular magnetic core 5 may be released, causing it to fall off within the annular space. To address these issues, the magnetic core unit 1 of this embodiment has a honeycomb structure at the end, increasing the surface area and improving heat dissipation. This suppresses temperature increases and prevents damage to the case members and degradation of the magnetic properties.

[0024] 1 and 2, the magnetic core unit of this embodiment is composed of two types of case members, a first case member and a second case member, and an annular magnetic core. The structure and materials of each will be described in detail.

[0025] (Structure of the first case member) Figure 4 is a front view of the first case member, Figure 5 is a partial cross-sectional view of the underside taken along line b-b', Figure 6 is a rear view of the first case member, Figure 7 is a partial cross-sectional view of the right side taken along line b-b', and Figure 8 is a partially enlarged view of a protrusion provided on the first case member. Two through holes 55, 56 are formed side by side in the first case member 10 via a partition portion 51 provided in the center. The shape of through holes 55, 56 is not particularly limited as long as it does not hinder the passage of the bus bars, but since the cross section of bus bars 101, 102 is rectangular, in the illustrated example, they have a half-arc oval shape with one arc portion cut off.

[0026] When the first case member 10 is viewed from above, the annular bottom plate portion 53 appears around the through holes 55, 56. As shown in FIGS. 4 and 5 , the annular bottom plate portion 53 has an inner cylindrical wall and an outer cylindrical wall that extend concentrically upward at its inner and outer edges, and is open at its upper end. The inner cylindrical wall constitutes a part of the inner wall portion 81 of the first case member 10, and the outer cylindrical wall constitutes a part of the outer wall portion 91. The inner wall portion 81 (inner cylindrical wall), the outer wall portion 91 (outer cylindrical wall), and the annular bottom plate portion 53 form a bottomed annular space 63 (opening). As shown in FIGS. 5 and 7 , the bottomed annular space 63 has a groove-shaped cross section when cut in the direction of the through holes 55, 56. The depth of the annular space 63 is set according to the thickness (height) of the annular magnetic core 5, and is capable of accommodating at least a portion of the annular magnetic core 5 in the height direction. In the illustrated example, the upper end of the partition 51 is formed flat and at the same height as the inner wall 81 and the outer wall 91, but may be at different heights.

[0027] The annular bottom plate portion 53 of the bottomed annular space 63 is provided with multiple protrusions 71 protruding toward the opening. These protrusions 71 allow the end face 8 of the annular magnetic core housed in the bottomed annular space 63 to face one surface of the annular bottom plate portion 53 without directly contacting it, with a distance of at least the height of the protrusions 71. The shape of the protrusions 71 is not particularly limited, and may be circular, polygonal, or other. In the examples shown in FIGS. 4 and 8 , the protrusions 71 are disk-shaped with a flat upper end. However, they may be tapered into a hemispherical or truncated cone shape to reduce the area of contact with the end face 8 of the annular magnetic core 5. Furthermore, the shape visible from the top may be ring-shaped or divided into multiple segments. In the illustrated example, the protrusions 71 are provided axially symmetrically at four positions. However, they may be formed in at least two positions with a predetermined distance between them, allowing the annular magnetic core to be stably positioned.

[0028] A honeycomb structure portion 110 is formed on the underside of the first case member 10. The honeycomb structure portion 110 is the lower portion of the bottomed annular space 63, and includes a plurality of bottomed holes 111, 112 arranged in multiple layers around the through holes 55, 56. The shapes of the bottomed holes 111, 112 are not particularly limited. The bottomed holes 111 adjacent to the through holes 55, 56 and the bottomed holes 112 surrounding them are partitioned by radial wall portions connecting to the inner wall portion 81 and the outer wall portion 91, and by wall portions provided between the bottomed holes 111, 112, thereby increasing the surface area and ensuring strength.

[0029] (Structure of second case member) Fig. 9 is a front view of the second case member, Fig. 10 is a partial cross-sectional view taken along line c-c' of the underside thereof, Fig. 11 is a partial cross-sectional view taken along line c-c' of the right side thereof, and Fig. 12 is a partially enlarged view of a protrusion provided on the second case member. The back of the second case member is omitted as it appears the same as in the front view. The second case member 20 has two through holes 57, 58 arranged side by side with a partition 52 provided in the center thereof. The configuration of the through holes 57, 58 is the same as that of the through holes 55, 56 of the first case member 10, and there are no limitations on the shape etc. as long as it does not hinder the passage of the bus bar.

[0030] When the second case member 20 is viewed from above, the annular bottom plate portion 54 appears around the through holes 57 and 58. As shown in FIG. 10 , the inner and outer edges of the annular bottom plate portion 54 have an inner cylindrical wall and an outer cylindrical wall that extend concentrically upward and are open at the upper end. The inner cylindrical wall constitutes a part of the inner wall portion 82 of the second case member 20, and the outer cylindrical wall constitutes a part of the outer wall portion 92. The inner wall portion 82 (inner cylindrical wall), the outer wall portion 92 (outer cylindrical wall), and the annular bottom plate portion 53 form a bottomed annular space 64 (opening). As shown in FIGS. 10 and 11 , the bottomed annular space 64 has a groove-shaped cross section in the direction of penetration of the through holes 57 and 58. The depth of the bottomed annular space 64 is set according to the thickness (height) of the annular magnetic core 5 so as to accommodate at least a portion of the annular magnetic core 5 in the height direction. In the illustrated example, the depth is approximately the same as the height of the annular magnetic core.

[0031] A step 32 is provided around the entire periphery on the upper end sides of the inner wall portion 82 and the outer wall portion 92, and is shaped to receive the upper end sides of the inner wall portion 82 and the outer wall portion 92 of the first case member 10. In the example shown, the upper end of the partition portion 52 is located lower than the inner wall portion 82 and the outer wall portion 92, is formed flat, and is at the same height as the lower end of the step 32. However, the upper end of the step 32 may be located at a different position depending on the structure of the first case member 10.

[0032] 11 and 12, the annular bottom plate portion 54 of the bottomed annular space 64 is provided with a plurality of protrusions 72 that protrude toward the opening side. The protrusions 72 allow the end face 8 of the annular magnetic core housed in the bottomed annular space 64 to face the annular bottom plate portion 54 with a gap of at least the height of the protrusions 72 without coming into direct contact with the annular bottom plate portion 54. The shape of the protrusions 72 is the same as the protrusions 71 of the first case member 10. The number, position, dimensions, etc. of the protrusions 72 may be the same as or different from those of the protrusions 71.

[0033] Although not shown, the annular bottom plate portion 54 appears around the through holes 57 and 58 on the back surface of the second case member 20, similar to when viewed from the front. The structure viewed from the back surface is similar to that of the front surface, and therefore will not be described further. The second case member 20 has two groove-shaped, bottomed annular spaces 64 that open in opposite directions in the penetration direction of the through holes 57 and 58. The bottomed annular spaces 64 are formed parallel to each other in the same direction via a partition wall 59. In the second case member 20 formed by injection molding, a draft angle of approximately 0.5 to 2° is provided on the inner wall on the side of the bottomed annular spaces 64. As a result, the bottomed annular spaces 64 are wider on the opening side and narrower on the annular bottom plate portion 54 side. The deeper the depth, the greater the difference in depth, which tends to increase the external dimensions of the second case member 20. In the magnetic core unit of this embodiment, the second case member 20 has multiple bottomed annular spaces 64, each of which has a shallow depth. This reduces the effect of the draft angle on the outer dimensions, and also increases the volume ratio of the bottomed annular space 64 that is effective for accommodating the annular magnetic core 5 .

[0034] The first case member 10 and the second case member 20 are preferably formed from a resin having excellent insulating properties, heat resistance, and moldability, and specifically, polyphenylene sulfide, liquid crystal polymer, polyethylene terephthalate, polybutylene terephthalate, nylon 66, etc. are preferred.

[0035] (Toroidal core) FIG. 13 is a perspective view showing the appearance of a toroidal magnetic core. The toroidal magnetic core 5 is a wound body having an end surface 8 facing an inner peripheral surface 6 and an outer peripheral surface 7, with an Fe-based amorphous alloy ribbon or an Fe-based nanocrystalline alloy ribbon wound thereon. The end surface 8 of the toroidal magnetic core 5 is a laminated surface where the ribbons are stacked. The Fe-based amorphous alloy ribbon preferably has a saturation magnetic flux density Bs of 1.4 T or more. For example, an Fe-based amorphous alloy ribbon such as an Fe-Si-B system, typified by Metglas (registered trademark) 2605SA1 material, can be used. Furthermore, compositions such as an Fe-Si-BC system or an Fe-Si-BC-Cr system containing other elements can also be used. A portion of Fe may be replaced with Co, Ni, or the like. An example of an alloy composition of the Fe-based amorphous alloy ribbon used in the embodiment of the present invention is Fe. a Si b B c C d M e (wherein M is at least one element selected from the group consisting of Cr, Mo, Mn, Zr, and Hf, and is preferably expressed in atomic percent as 50≦a≦90, 2≦b≦15, 5≦c≦30, 0≦d≦3, 0≦e≦10, and a+b+c+d+e=100). The alloy composition is not particularly limited to this, and can be selected depending on the required properties.

[0036] The Fe-based nanocrystalline alloy ribbon preferably has a saturation magnetic flux density Bs of 1.2 T or more. Specifically, for example, amorphous alloy ribbons for Fe-based nanocrystalline alloys such as Fe-Si-B-Cu-Nb, Fe-Cu-Si-B, Fe-Cu-B, and Fe-Ni-Cu-Si-B can be used. Alloys in which some of these elements are substituted, and alloys to which other elements are added, may also be used. An example of an alloy composition used in the embodiment of the present invention is Fe 100-x-y Ax X y (However, A is Cu and / or Au, and X is at least one element selected from the group consisting of B, Si, S, C, P, Al, Ge, B, Sn, Nb, Mo, and Cr), preferably represented by atomic percentages of 0 < x ≦ 5 and 10 ≦ y ≦ 24. A part of Fe may be replaced with Ni or Co, and the replacement amount is preferably 5 or less in atomic percentage. Note that a nanocrystal is a fine crystal structure with a particle size of 100 nm or less.

[0037] (Magnetic core unit) FIG. 14 is a front view showing a state in which the first case member and the second case member are combined. FIG. 15 is a partial cross-sectional view taken along line a-a' of the lower surface thereof, and FIG. 16 is a partial cross-sectional view taken along line a-a' of the right side surface thereof. The configuration shown in FIG. 14 is the same as the back surface of the first case member 10 shown in FIG. 6, so the description thereof is omitted. Also, the annular core is omitted from each figure, and the positional relationship between the members and the like will be described while referring to FIGS. 1, FIG. 2, etc.

[0038] As shown in FIG. 15, the second case member 20 is centered, and the first case member 10 is combined so as to be positioned above and below it. The inner cylindrical wall and the outer cylindrical wall of the first case member 10 are fitted into the step 32 of the second case member 20, so that the inner circumference 151 and the outer circumference 152 of the magnetic core unit 1 can be formed substantially without a step.

[0039] When the first case member 10 and the second case member 20 are combined, the through holes 55, 57 and the through holes 56, 58 communicate with each other to form the through holes 131, 132 of the magnetic core unit 1. Also, the partition portion 51 of the first case member 10 and the partition portion 52 of the second case member 20 are connected to form the partition portion 141 of the magnetic core unit 1. Further, a plurality of annular space portions 161 arranged in the same axial direction are formed by the bottomed annular spaces 63 and 64 of each case member, and an annular core 5 is arranged in each of them as shown in FIG. 2.

[0040] Protrusions 71 and 72 protrude into the annular space 161 so as to face the end 8 of the annular core 5. In a state where the first case member 10 and the second case member 20 are combined, the interval w determined by the upper ends of the protrusions 71 and 72 is wider than the height h of the annular core 5 (w>h), so as not to press the annular core 5. Also, during assembly, the protrusions 71 and 72 restrict the movement of the annular core 5 within the annular space 161. If the interval w between the protrusions 71 and 72 has an upper limit of +0.5 mm with respect to the height h of the annular core 5 (0<w - h≦0.5), it is preferable because the movement amount of the annular core 5 can be further restricted.

[0041] (Method for manufacturing a core unit) Next, an example of a method for manufacturing the core unit 1 will be described. First, the second case member 20 is placed vertically so that its bottomed annular space 64 appears vertically. Next, after applying a predetermined amount of adhesive on the surface of the annular bottom plate portion 54, the annular core 5 is housed in the bottomed annular space 64. Further, the first case member 10 with a predetermined amount of adhesive applied to the annular bottom plate portion 53 is combined so as to cover the annular core 5 from above (the first step). Subsequently, the core unit being assembled is turned upside down, a predetermined amount of adhesive is applied to the other annular bottom plate portion 54 of the second case member 20, and then another annular core 5 is housed in the bottomed annular space 6'4. Then, another first case member 10 with a predetermined amount of adhesive applied to the annular bottom plate portion 53 is combined so as to cover the annular core 5 from above (the second step). Next, the adhesive is cured to adhesively fix each case member 10, 20 and the annular core 5 (the third step), and the core unit 1 is completed. The adhesive is not particularly limited as long as it can adhere the respective members, but a thermosetting adhesive can be used, and among them, a silicone adhesive or an epoxy-based adhesive having a viscosity that is difficult to sag even on a vertical surface is preferable.

[0042] During assembly, the adhesive is uncured, allowing the annular core 5 to move easily and sinking within the annular space 161 due to its own weight when placed upright. For example, after the second step, the annular core 5 in the upper annular space 161 may be biased toward the annular bottom plate 54 of the second case member 20, while the annular core 5 in the lower annular space 161 may be biased toward the annular bottom plate 53 of the first case member 10. If the protrusions 71, 72 protruding into the annular space 161 were not provided, one of the end faces 8 of the annular core 5 would abut against one surface of the annular bottom plate 53 or 54, causing the adhesive to spread thinly across the end face 8 of the annular core 5. On the other end face 8 side, the gap between the annular bottom plate 53 or 54 would widen, resulting in an insufficient adhesive surface area. In this state, after the adhesive hardens, the annular magnetic core 5 is susceptible to stress caused by shrinkage during hardening of the adhesive, which may result in deterioration of the magnetic properties or insufficient adhesion, making it difficult to obtain a reliable fixing force.

[0043] On the other hand, by providing the protrusions 71 and 72 that protrude into the annular space 161, even if the annular magnetic core 5 is misaligned within the annular space 161 during assembly, a space is secured between the end face 8 of the annular magnetic core 5 and the annular bottom plate 53 or 54, preventing the end face 8 of the annular magnetic core 5 from coming into contact with the annular bottom plate 53 or 54. Because the applied adhesive accumulates in this space, even if the annular magnetic core 5 moves between the protrusions 71 and 72, the adhesive is prevented from spreading unnecessarily over the end face 8 of the annular magnetic core 5. Furthermore, by limiting the amount of movement of the annular magnetic core 5 between the protrusions 71 and 72, the adhesive area of the end face 8 of the annular magnetic core 5 is prevented from becoming insufficient. This ensures a secure connection between the annular magnetic core 5 and each case member 10, 20 while suppressing degradation of magnetic properties due to stress caused by shrinkage during adhesive hardening.

[0044] In addition, by limiting the amount of movement of the annular magnetic core 5 and reducing the movement energy imparted to the annular magnetic core 5 even if the annular magnetic core 5 becomes loose after being glued, it is possible to prevent the annular magnetic core 5 from colliding with the inner wall of the case in the annular space portion 161 and being damaged. [Explanation of symbols]

[0045] 1 core unit 5. Toroidal core 10 First case member 20 Second case member 71, 72 Protrusion 161 Annular space 101, 102 busbars

Claims

1. The magnetic core includes a plurality of resin cases each formed by combining a plurality of case members and each having annular spaces arranged in the same axial direction, and annular magnetic cores housed in each of the annular spaces of the resin cases, Each of the case members includes a plurality of protrusions protruding in the axial direction in the annular space portion, the annular magnetic core is a wound body formed by winding an Fe-based amorphous alloy ribbon or an Fe-based nanocrystalline alloy ribbon, and has an inner periphery and an end face facing the outer periphery, the annular magnetic core and the resin case are adhesively fixed together such that the surface of the case member on which the protrusion is formed faces the end face of the annular magnetic core; At least two of the toroidal cores are arranged side by side; The magnetic core unit includes a group of hole rows partitioned by wall portions on both end sides of the resin case in the axial direction.

2. The magnetic core unit according to claim 1, a through hole on the inner circumferential side of the annular magnetic core; The through hole is partitioned in the axial direction by partitions formed by a plurality of case members.

3. The magnetic core unit according to claim 1 or 2, the resin case includes a first case member and a second case member, each of the first case member and the second case member has an opening whose cross section cut in the axial direction is groove-shaped; the first case member has one groove-shaped opening that opens in the axial direction, the second case member has two groove-shaped openings that open in the axial direction and that open in opposite directions to each other, A magnetic core unit in which two of the first case members are combined with the second case member, and two annular accommodating sections are formed by combining a groove-shaped opening of the first case member with a groove-shaped opening of the second case member.

4. The magnetic core unit according to claim 1, The core unit is configured such that the hole array assembly is composed of a plurality of bottomed holes.

5. A noise filter comprising the core unit according to any one of claims 1 to 4 and a plurality of bus bars.

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