Core unit and noise filter using the same

Abstract

To provide a magnet core unit which can suppress deterioration of magnetic characteristics due to stress caused by shrinkage during curing of an adhesive used for fixing a magnet core while surely obtaining fixing force of the magnet core in a case, and to provide a noise filter using the same.SOLUTION: A magnet core unit includes a resin case which is constituted by combining a plurality of case members and has a plurality of annular space parts arranged in the same axial direction, and a plurality of projection parts which have annular magnet cores stored in the respective annular space parts of the resin case, and project in the axial direction in the annular space parts in the respective case members. The annular magnet core is a wound body having an end face facing the inner periphery and the outer periphery with which an Fe-based amorphous alloy ribbon or an Fe-based nanocrystal alloy ribbon is wound. The annular magnet cores and the resin case are bonded and fixed so that a surface formed with the projection parts of the case member and the end faces of the annular magnet cores face each other, and the magnet core unit has through holes on the inner peripheral sides of the annular magnet cores.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] In a path where a relatively large current exceeding 100 A flows, such as between an in-vehicle charging circuit of a hybrid vehicle or an electric vehicle and an external power source, or between an AC motor and a power supply circuit, a bus bar (a bar-shaped thick copper plate) is used. Since the current flowing through the bus bar is a source of noise, in consideration of the influence on peripheral electronic devices, a core is arranged in the current path, and a noise filter is configured by passing the bus bar through it. In such a noise filter, a core unit in which the periphery of the core is covered with a resin member is used to insulate the bus bar from the core or other members.

[0003] Although the form of the core unit varies, Patent Document 1 discloses a noise filter having a core case structure in which annular cores are coaxially stacked. As shown in FIG. 17, it is composed of a resin case including an upper core case 510, a lower core case 530, an intermediate core case 520, and a connecting member 700, and a plurality of cores 610, 620 housed in an annular housing portion formed in the resin case. Slit grooves are provided on the inner peripheral sides of the upper core case 510 and the lower core case 530, and the connecting member 700 is fitted therein and connected together with the intermediate core case 520 to form a core case structure in which the cores 610, 620 are housed in the annular housing portion. The depth of the annular housing portion corresponds to the thickness of the cores 610, 620, and the cores 610, 620 are sandwiched between the upper core case 510, the lower core case 530, and the intermediate core case 520 and are fixed as a whole.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a path through which a relatively large current flows, as a magnetic material of a magnetic core used for a noise filter, a metallic magnetic material having a saturation magnetic flux density larger than that of ferrite is selected. For example, Fe-based amorphous alloys or Fe-based nanocrystalline alloys are often used. A noise filter using an annular magnetic core formed by winding a thin strip of an Fe-based amorphous alloy or an Fe-based nanocrystalline alloy (hereinafter sometimes referred to as an alloy thin strip) in an annular shape can easily obtain a high impedance in a wide frequency range from several kHz to several MHz, and is suitable for preventing malfunction of in-vehicle electronic devices due to noise in an automobile in which data communication between a plurality of electronic control devices is performed by an in-vehicle LAN (Local Area Network).

[0006] On the other hand, magnetic materials such as Fe-based amorphous alloys and Fe-based nanocrystalline alloys have large magnetostriction, are sensitive to shock and stress, and their thin strips are brittle. Therefore, in the method of pressing and holding the magnetic core in the annular storage portion with a core case as in a conventional noise filter, deterioration of magnetic characteristics such as an increase in coercive force and a decrease in permeability may occur. Also, if the pressing force is insufficient, the magnetic core may move within the annular storage portion, and the magnetic core itself may be damaged due to collision with the core case.

[0007] Therefore, the annular storage portion is made to be approximately the same thickness as the magnetic core or thicker, and the core case and the magnetic core are adhesively fixed. However, even when the magnetic core is fixed by adhesion, stress is applied to the magnetic core due to shrinkage during curing of the adhesive, and there still remains a problem that the magnetic characteristics deteriorate, although to a different degree. Details will be described later, but particularly in a structure using a plurality of magnetic cores such as the conventional noise filter shown in Patent Document 1, this problem may become prominent.

[0008] Therefore, an object of the present invention is to provide a core unit capable of suppressing a decrease in magnetic characteristics due to stress caused by shrinkage during curing of an adhesive while obtaining a fixing force of a core in a case by the adhesive, and a noise filter using the same.

Means for Solving the Problems

[0009] A first invention includes a resin case formed by combining a plurality of case members and having a plurality of annular space portions arranged in the same axial direction, and annular cores respectively accommodated in the annular space portions of the resin case. Each of the case members is provided with a plurality of protrusions protruding in the axial direction in the annular space portion. The annular core is a wound body having an inner circumference, an outer circumference, and end faces facing each other, wound with an Fe-based amorphous alloy ribbon or an Fe-based nanocrystalline alloy ribbon. The annular core and the resin case are adhesively fixed so that the surface of the case member on which the protrusion is formed faces the end face of the annular core, and at least two of the annular cores are arranged side by side, which is a core unit.

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

[0011] In the core unit of the present invention, 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 with a groove-shaped cross section cut in the axial direction. The first case member has one groove-shaped opening opening in the axial direction, and the second case member has two groove-shaped openings opening in the axial direction and opening in opposite directions to each other. It is preferable to combine two of the first case members with the second case member and combine the groove-shaped opening of the first case member and the groove-shaped opening of the second case member to form two annular accommodation portions.

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

[0013] The second invention is a noise filter composed of a plurality of busbars and a magnetic core unit of the first invention, wherein the busbar is passed through the through-hole of the magnetic core unit.

Advantages of the Invention

[0014] According to the present invention, it is possible to provide a magnetic core unit capable of suppressing a decrease in magnetic characteristics due to stress caused by shrinkage during curing of an adhesive while obtaining a fixing force of the magnetic core in a case by the adhesive, and a noise filter using the same.

Brief Description of the Drawings

[0015]

Figure 1

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Figure 17

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited thereto. In this specification, in the description of the structure, as a relative positional relationship, when explaining with reference to the drawings, one direction may be described as the upper side and the opposite direction as the lower side, but that does not indicate a common positional relationship or direction among the drawings. Also, in part or all of the figures, structural parts that are unnecessary for the description are omitted, and there are parts that are enlarged or otherwise illustrated to facilitate the description. The shapes and the like shown in the description are not limited only to those descriptions and drawings unless otherwise specified. Furthermore, in the description, the same names and reference numerals indicate the same or similar members, and detailed descriptions may be omitted even if they are illustrated.

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

[0018] Annular magnetic cores 5 are arranged on both sides in the y-axis direction of the second case member 20. Although details will be described later, the annular magnetic cores 5 are housed in an annular space portion formed by combining the first case member 10 and the second case member 20, and are adhesively fixed to the first case member 10 and the second case member 20 respectively by an adhesive. The first case member 10 and the second case member 20 have a structure provided with protrusions protruding inward in the annular space portion.

[0019] The alloy ribbon constituting the annular magnetic core 5 has a larger undulation as it is wider and made, and the space factor of the magnetic core using such an alloy ribbon tends to decrease easily. It is known that the decrease in the space factor affects the impedance characteristics of the noise filter. Therefore, in the magnetic core unit of this embodiment, by using a plurality of annular magnetic cores 5 using alloy ribbons with small undulations obtained by cutting wide alloy ribbons, the magnetic path cross-sectional area is ensured and the decrease in the space factor of the magnetic core is prevented, thereby preventing deterioration of the characteristics of the noise filter such as not obtaining a high impedance at a predetermined frequency.

[0020] In the magnetic core unit 1 composed of combining various components, an annular space is closed by the first case member 10 and the second case member 20, and the annular magnetic core 5 accommodated in the annular space does not appear on the surface in terms of appearance. Both ends of the magnetic core unit 1 in the y-axis direction are formed as a honeycomb structure portion 110 configured as an aggregate of a plurality of bottomed holes 111 and 112 formed in the first case member 10. Here, the hole shape in the honeycomb structure is not limited to a hexagonal shape. Further, the magnetic core unit 1 is formed with two through holes 131 and 132 through which bus bars partitioned by a partition portion 141 on the inner peripheral side of the annular magnetic core 5 are passed.

[0021] FIG. 3 is an external perspective view of a noise filter according to an 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 the through holes 131 and 132 partitioned by the partition portion 141 of the magnetic core unit 1 so that their surface directions are the same. By the through holes 131 and 132 of the magnetic core unit 1, the bus bars 101 and 102 can be easily positioned and arranged. Further, since the space distance between the bus bars 101 and 102 is determined by the partition portion 141, electrical insulation can be easily ensured. Also, since the annular magnetic core 5 is arranged in the annular space closed by the first case member 10 and the second case member 20, it is also 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 the bus bars 101 and 102 are arranged at equal intervals and extend linearly. The forms of the bus bars 101 and 102 are not limited thereto, and can be deformed into various forms as long as they can pass through the through holes 131 and 132 of the magnetic core unit 1. For example, the ends of the bus bars 101 and 102 may be bent, or for example, formed in an L shape so that the interval between the bus bars 101 and 102 widens on at least one end side of the magnetic core unit 1.

[0023] The space where the noise filter is placed is often limited, and there is always a requirement to make the noise filter compact. When trying to make the noise filter compact, the magnetic core unit 1 and the bus bars 101 and 102 will naturally be close to each other. When the bus bars 101 and 102 are energized and a large current flows through them, the bus bars will heat up and reach a high temperature due to copper loss caused by resistance. Therefore, the magnetic core unit 1 close to the bus bars 101 and 102 is also likely to reach a high temperature. If the magnetic core unit 1 becomes extremely hot, the first case member 10 and the second case member 20 may be thermally damaged. In addition, there are differences in the linear expansion coefficients among the case members 10 and 20, the annular core 5, and the adhesive that fixes them. Due to the dimensional changes caused by the difference in the linear expansion coefficients with temperature changes, the stress applied to the annular core 5 changes, and the magnetic characteristics may deteriorate. Furthermore, the adhesive fixation of the annular core 5 may be released, and the annular core 5 may fall off within the annular space portion. In response to such problems, the magnetic core unit 1 of this embodiment has a honeycomb structure portion at the end to increase the surface area and enhance the heat dissipation performance. Thereby, the temperature rise can be suppressed, and damage to the case member and deterioration of the magnetic characteristics can be prevented.

[0024] As shown in FIGS. 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 core. The structure and material of each will be described in detail.

[0025] (Structure of the first case member) FIG. 4 is a front view of the first case member, FIG. 5 is a partial cross-sectional view taken along the line b-b' of its lower surface, FIG. 6 is a rear view of it, FIG. 7 is a partial cross-sectional view taken along the line b-b' of its right side surface, and FIG. 8 is a partially enlarged view of the protrusion provided on the first case member. In the first case member 10, two through holes 55 and 56 arranged via a partition portion 51 provided at the center thereof are formed. The shapes of the through holes 55 and 56 are not particularly limited as long as they do not impede the passage of the bus bars. However, since the cross-sections of the bus bars 101 and 102 are rectangular, in the illustrated example, they are oblong with one arc portion cut off, which is a semi-elliptical shape.

[0026] When the first case member 10 is viewed from the upper surface side, an annular bottom plate portion 53 appears around the through holes 55 and 56. As shown in FIGS. 4 and 5, the inner edge portion and the outer edge portion have an inner cylindrical wall and an outer cylindrical wall that extend concentrically upward, and the upper end side is open. 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. A bottomed annular space 63 (opening) is formed by the inner wall portion 81 (inner cylindrical wall), the outer wall portion 91 (outer cylindrical wall), and the annular bottom plate portion 53. As shown in FIGS. 5 and 7, the cross-sectional shape of the bottomed annular space 63 that appears in the cross-section cut in the through direction of the through holes 55 and 56 is a groove shape. Its depth is set according to the thickness (height) of the annular core 5, and at least a part of the annular core 5 in the height direction can be accommodated. In the illustrated example, the upper end of the partition portion 51 is formed flat at the same height as the inner wall portion 81 and the outer wall portion 91, but it may be at a different height.

[0027] Further, a plurality of protrusions 71 protruding toward the opening side are provided on the annular bottom plate portion 53 of the bottomed annular space 63. By the protrusions 71, the end face 8 of the annular core accommodated in the bottomed annular space 63 can be opposed with a space at least corresponding to the height of the protrusions 71 without directly contacting the one surface of the annular bottom plate portion 53. The shape of the protrusions 71 is not particularly limited, such as circular or polygonal. In the examples shown in FIGS. 4 and 8, the protrusions 71 are disk-shaped with a flat upper end side, but if the area in contact with the end face 8 of the annular core 5 is to be reduced, it may be formed to taper as a hemispherical shape or a truncated cone shape. Also, the shape visible from the upper surface side may be ring-shaped or divided into a plurality of forms. In the illustrated example, the protrusions 71 are provided axially symmetrically at four positions, but they may be formed at least at two or more positions with a predetermined interval at positions where the annular core can be stably arranged.

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

[0029] (Structure of the second case member) FIG. 9 is a front view of the second case member, FIG. 10 is a partial cross-sectional view taken along the line c-c' of its lower surface, FIG. 11 is a partial cross-sectional view taken along the line c-c' of its right side surface, and FIG. 12 is a partially enlarged view of the protrusion provided on the second case member. The back surface of the second case member appears the same as the front view, so it is omitted. In the second case member 20, two through holes 57, 58 arranged via a partition portion 52 provided at the center thereof are formed. The forms of the through holes 57, 58 are the same as those of the through holes 55, 56 of the first case member 10, and there is no limitation on the shape or the like as long as it does not hinder passing the bus bar.

[0030] When the second case member 20 is viewed from the upper surface side, an annular bottom plate portion 54 appears around the through holes 57, 58. As shown in FIG. 10, its inner edge portion and outer edge portion have an inner cylindrical wall and an outer cylindrical wall extending concentrically upward, and the upper end side is open. The inner cylindrical wall constitutes a part of the inner side wall portion 82 of the second case member 20, and the outer cylindrical wall constitutes a part of the outer side wall portion 92. A bottomed annular space 64 (opening) is formed by the inner side wall portion 82 (inner cylindrical wall), the outer side wall portion 92 (outer cylindrical wall), and the annular bottom plate portion 53. As shown in FIGS. 10 and 11, the cross-sectional shape of the bottomed annular space 64 is a groove shape in the cross-section in the penetrating direction of the through holes 57, 58. Its depth is set according to the thickness (height) of the annular core 5, and at least a part in the height direction of the annular core 5 can be accommodated. In the illustrated example, the depth is approximately the same as the height of the annular core.

[0031] A step 32 is provided over the entire circumference on the upper end sides of the inner wall portion 82 and the outer wall portion 92, and it has a shape that receives the upper end sides of the inner wall portion 82 and the outer wall portion 92 of the first case member 10. In the illustrated example, the upper end of the partition portion 52 is at a position 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. Note that it may be at a position different from the lower end of the step 32 according to the structure of the first case member 10.

[0032] As shown in FIGS. 11 and 12, a plurality of protrusions 72 protruding toward the opening side are provided on the annular bottom plate portion 54 of the bottomed annular space 64. Due to the protrusions 72, the end face 8 of the annular core accommodated in the bottomed annular space 64 can be opposed with a gap of at least the height of the protrusions 72 without directly contacting the annular bottom plate portion 54. The form of the protrusions 72 is the same as that of the protrusions 71 of the first case member 10. Note that the number of formations, positions, dimensions, etc. may be the same as or different from those of the protrusions 71.

[0033] Although not shown, on the back surface of the second case member 20, the annular bottom plate portion 54 appears around the through holes 57 and 58 in the same manner as when viewed from the front side. The structure viewed from the back side is the same as that from the front side, so the description is omitted. The second case member 20 has two groove-shaped bottomed annular spaces 64 that open in opposite directions in the through direction of the through holes 57 and 58, and the bottomed annular spaces 64 are formed in parallel in the same direction via a partition wall 59. In the second case member 20 formed by injection molding, a draft gradient of about 0.5 to 2° is provided on the inner wall on the side of the bottomed annular space 64. Thereby, the bottomed annular space 64 is wide on the opening side and narrow on the side of the annular bottom plate portion 54, and the difference becomes larger as the depth increases, and the outer shape of the second case member 20 tends to become larger. In the core unit of the present embodiment, a plurality of bottomed annular spaces 64 of the second case member 20 are provided, and the respective depths are made shallower. Thereby, the influence on the outer dimensions due to the draft gradient can be reduced, and the effective volume ratio for accommodating the annular core 5 in the bottomed annular space 64 can be increased.

[0034] The first case member 10 and the second case member 20 are preferably formed of a resin having excellent insulation, heat resistance, and moldability. Specifically, polyphenylene sulfide, liquid crystal polymer, polyethylene terephthalate, polybutylene terephthalate, nylon 66, etc. are preferable.

[0035] (Annular core) FIG. 13 is a perspective view showing the appearance of the annular core. It is a wound body having an inner peripheral surface 6, an outer peripheral surface 7, and end faces 8 facing each other, which is formed by winding an Fe-based amorphous alloy ribbon or an Fe-based nanocrystalline alloy ribbon. The end face 8 of the annular core 5 is a laminated surface where the ribbons are stacked. As the Fe-based amorphous alloy ribbon, it is preferable to have 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 Fe-Si-B-C system and Fe-Si-B-C-Cr system containing other elements can also be adopted. A part of Fe may be substituted with Co, Ni, etc. As an example of the alloy composition of the Fe-based amorphous alloy ribbon used in the embodiment of the present invention, Fe a Si b B c C d M e (However, M is at least one element selected from the group consisting of Cr, Mo, Mn, Zr, and Hf, and is represented by atomic % as 50 ≦ a ≦ 90, 2 ≦ b ≦ 15, 5 ≦ c ≦ 30, 0 ≦ d ≦ 3, 0 ≦ e ≦ 10, a + b + c + d + e = 100), and those represented by this are preferable. The alloy composition is not particularly limited to this and can be selected according to the required characteristics.

[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 system, Fe-Cu-Si-B system, Fe-Cu-B system, Fe-Ni-Cu-Si-B system, etc. can be used. Alloys in which some of these elements are substituted, and alloys to which other elements are added may also be used. As an example of the alloy composition used in the embodiment of the present invention, 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 where 0 < x ≤ 5 and 10 ≤ y ≤ 24. A part of Fe may be replaced by 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] (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 its lower surface, and FIG. 16 is a partial cross-sectional view taken along line a-a' of its right side surface. 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 is omitted. Also, the annular core is omitted from each figure, and the positional relationship of each member, etc. will be described with reference to FIGS. 1, 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 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 to form the through holes 131, 132 of the 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 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 project into the annular space portion 161 so as to face the end portion 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. Further, during assembly, the protrusions 71 and 72 restrict the movement of the annular core 5 within the annular space portion 161. However, if the interval w between the protrusions 71 and 72 has a maximum 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 64. 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 adhesive having a viscosity that is difficult to sag even on a vertical surface is preferable.

[0042] In the intermediate stage of assembly, since the adhesive is uncured, the annular core 5 can be easily moved, and in the vertical state, it sinks into the annular space portion 161 due to its own weight. For example, in the state where the second step is completed, the annular core 5 in the upper annular space portion 161 may shift toward the annular bottom plate portion 54 of the second case member 20, and the annular core 5 in the lower annular space portion 161 may shift toward the annular bottom plate portion 53 of the first case member 10. If the protruding portions 71 and 72 that protrude into the annular space portion 161 are not provided, one of the end faces 8 of the annular core 5 abuts against one surface of the annular bottom plate portion 53 or the annular bottom plate portion 54, and the intervening adhesive is likely to spread thinly and wet the end face 8 of the annular core 5. On the other end face 8 side, the distance from the annular bottom plate portion 53 or the annular bottom plate portion 54 increases, and the adhesive area is likely to be insufficient. In such a state, after the adhesive is cured, the annular core 5 is likely to be affected by the stress caused by the shrinkage during the curing of the adhesive, and the magnetic characteristics may deteriorate, or the adhesion may be insufficient and the fixing force may not be obtained reliably.

[0043] On the other hand, by providing the protruding portions 71 and 72 that protrude into the annular space portion 161, even if the annular core 5 in the annular space portion 161 shifts during assembly, a space is ensured between the end face 8 of the annular core 5 and the annular bottom plate portion 53 or the annular bottom plate portion 54, and the end face 8 of the annular core 5 does not abut against the annular bottom plate portion 53 or the annular bottom plate portion 54. Since the applied adhesive accumulates in the space, even if the annular core 5 moves between the protruding portions 71 and 72, it is possible to prevent the adhesive from spreading uselessly and wetting the end face 8 of the annular core 5. Further, by restricting the amount of movement of the annular core 5 between the protruding portions 71 and 72, it is possible to prevent the adhesive area of the end face 8 of the annular core 5 from being insufficient. Thereby, while reliably obtaining the fixing force between the annular core 5 and each case member 10, 20, it is possible to suppress the deterioration of the magnetic characteristics due to the stress caused by the shrinkage during the curing of the adhesive.

[0044] Also, by restricting the amount of movement of the annular core 5 and reducing the movement energy applied to the annular core 5 even when the fixing of the annular core 5 is released after adhesion, it is possible to prevent the annular core 5 from colliding with the case inner wall in the annular space portion 161 and being damaged.

Explanation of Reference Numerals

[0045] 1 Core unit 5 Annular core 10 First case member 20 Second case member 71, 72 Protrusions 161 Annular space part 101, 102 Busbars

Claims

1. The magnetic core includes a plurality of resin cases each having annular spaces arranged in the same axial direction, the resin cases being configured by combining a plurality of case members, and annular magnetic cores each accommodated in the annular spaces of the resin cases; Each of the case members is provided with 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 circumference and an end face facing the outer circumference, the annular magnetic core and the resin case are adhesively fixed together such that a surface of the case member on which the protrusion is formed faces an 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 rows of holes partitioned by walls on both ends of the resin case in the axial direction.

2. The magnetic core unit according to claim 1, A through hole is provided on the inner peripheral side of the annular magnetic core, The through hole is partitioned in the axial direction by a partition portion 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 having a groove-shaped cross section cut in the axial direction, The first case member has a groove-shaped opening portion that opens in the axial direction, The second case member has two groove-shaped openings that open in the axial direction and 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 a groove-shaped opening of the first case member is combined with a groove-shaped opening of the second case member to form two annular housing portions.

4. The magnetic core unit according to claim 1, The assembly of hole rows is composed of a plurality of bottomed holes, forming a magnetic core unit.

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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