Line filter and electronic apparatus

Abstract

To provide a line filter capable of suppressing a possibility for a core to be broken while securing high differential mode inductance.SOLUTION: A line filter 10 includes an annular core 1 and a first magnetic body 2. When a direction in which a shaft rotated by the annular core 1 extends is a shaft direction, the core 1 is provided with an inner peripheral surface 1a, an outer peripheral surface 1b, one end side end surface in the shaft direction, and an end surface on the other end surface in the shaft direction. The first magnetic substance 2 is provided with a first plate-like portion 2a and a first projection 2c. The first plate-like portion 2a is placed inside the core 1 so that a principal surface of the first plate-like portion 2a goes along the shaft direction. The first projection 2c protrudes radially outside of the core 1 from one end 2b in the shaft direction of the first plate-like portion 2a. An end of the first projection 2c is located on the outer peripheral surface 1b side of the core 1 from an inner peripheral surface 1a of the core 1. The first plate-like portion 2a and the inner peripheral surface 1a of the core 1 are separate.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a line filter and an electronic device. [Background technology]

[0002] The filter disclosed in Patent Document 1 includes a first magnetic ring, a second magnetic ring, two windings, and a magnetic conductive element. The second magnetic ring covers the first magnetic ring. The two windings are wound around the second magnetic ring, respectively. The magnetic conductive element is assembled to the second magnetic ring. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2009 / 0051478 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors of the present application have discovered the following problems. In such a filter, the second magnetic ring and the magnetic conductive element are placed close to each other to ensure high differential mode inductance, which can cause the magnetic conductive element and the second magnetic ring to come into contact with each other and be damaged.

[0005] In view of the above-mentioned problems, an object of the present invention is to provide a line filter that can reduce the risk of core damage while ensuring high differential mode inductance. [Means for solving the problem]

[0006] A line filter according to the present disclosure comprises an annular core and a first magnetic body, wherein, when the direction in which an axis circumferentially circumferentially extends is defined as the axial direction, the core comprises an inner peripheral surface, an outer peripheral surface, an end face on one end side in the axial direction (e.g., one of end faces 1c and 1d), and an end face on the other end side in the axial direction (e.g., the other of end faces 1c and 1d), the first magnetic body comprises a first plate-shaped portion and a first protrusion, the first plate-shaped portion is disposed inside the core such that a main surface of the first plate-shaped portion is along the axial direction, the first protrusion protrudes radially outward from one end of the first plate-shaped portion in the axial direction, and a tip of the first protrusion is located on the outer peripheral surface side of the core from the inner peripheral surface of the core, and the first plate-shaped portion and the inner peripheral surface of the core are spaced apart.

[0007] In the above-described line filter, the first protrusion may be spaced apart from an end face of the core on one end side in the axial direction.

[0008] Furthermore, in the above-described line filter, the first protrusion has an opposing surface facing one end face of the core in the axial direction, the first plate-shaped portion has an opposing end face facing the inner peripheral surface of the core along the axial direction, and the distance between the opposing surface of the first protrusion and one end face of the core in the axial direction is shorter than the distance between the opposing end face of the first plate-shaped portion and the inner peripheral surface of the core.

[0009] In the above-described line filter, the core may have a magnetic permeability equal to or greater than that of the first magnetic body.

[0010] The electronic device according to the present disclosure includes a substrate and a metal housing, the substrate having the above-described line filter mounted thereon, and the substrate being housed in the metal housing.

[0011] Furthermore, the above-described line filter may further include a second magnetic body, the second magnetic body including a second plate-shaped portion and a second protrusion, the second plate-shaped portion being arranged inside the core so that a main surface of the second plate-shaped portion is along the axial direction, the second protrusion protruding from one end of the second plate-shaped portion in the axial direction to the radially outer side of the core, a tip of the second protrusion being located from the inner peripheral surface of the core toward the outer peripheral surface of the core, and the second plate-shaped portion and the inner peripheral surface of the core being spaced apart. [Effects of the Invention]

[0012] The present invention can reduce the risk of core damage while ensuring high differential mode inductance. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a perspective view showing a configuration example of a line filter according to a first embodiment. [Figure 2] 1 is a perspective view showing a configuration example of a line filter according to a first embodiment, with windings removed. FIG. [Figure 3] 1 is an exploded perspective view showing a configuration example of a line filter according to a first embodiment. [Figure 4] 1 is a perspective view showing an example of a configuration of a core to which first and second magnetic bodies are assembled. FIG. [Figure 5] FIG. 4 is a schematic diagram showing a cross section of the core taken along line IV-IV. [Figure 6] 10 is a perspective view showing another example of the configuration of the core to which the first and second magnetic bodies are assembled. FIG. [Figure 7] FIG. 1 is a perspective view showing an example of a line filter disposed between metal plates. [Figure 8] FIG. 10 is a perspective view showing another example of a line filter disposed between metal plates. [Figure 9] 10A and 10B are diagrams showing magnetic flux distribution in a cross section of the line filter taken along each cutting line. [Figure 10] FIG. 10 is a diagram illustrating an example of a magnetic flux distribution around a line filter. [Figure 11] 5A to 5C are schematic diagrams illustrating a method for manufacturing the line filter according to the first embodiment. [Figure 12] 5A to 5C are schematic diagrams illustrating a method for manufacturing the line filter according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. In addition, the following description and drawings have been simplified as appropriate for clarity of explanation.

[0015] (Embodiment 1) The configuration of the line filter according to the first embodiment will be described with reference to FIGS.

[0016] Fig. 1 is a perspective view showing an example of the configuration of a line filter according to embodiment 1. Fig. 2 is a perspective view showing an example of the configuration of a line filter according to embodiment 1 with windings removed. Fig. 3 is an exploded perspective view showing an example of the configuration of a line filter according to embodiment 1. Fig. 4 is a perspective view showing an example of the configuration of a core to which first and second magnetic bodies are assembled. Fig. 5 is a schematic view showing a cross section of the core taken along line IV-IV. Fig. 6 is a perspective view showing another example of the configuration of a core to which first and second magnetic bodies are assembled.

[0017] Naturally, the right-handed XYZ coordinate system shown in Figure 1 and other drawings is for the convenience of explaining the positional relationships of the components. Normally, the positive direction of the Z axis is vertically upward, and the XY plane is a horizontal plane, which is common among the drawings.

[0018] 1 to 3, the line filter 10 includes a core 1, a first magnetic body 2, a case 4, a first cover 5, a second cover 6, and windings 7 and 8. The line filter 10 according to the present embodiment includes a second magnetic body 3.

[0019] As shown in FIGS. 4 and 5, the core 1 may be an annular body, specifically, an annular body extending in the shape of a rectangle with rounded corners, a substantially perfect circle, a substantially ellipse, or an athletics track. The core 1 according to this embodiment is an annular body extending in the shape of a rectangle with rounded corners. The core 21 shown in FIG. 6 has the same configuration as the core 1 according to this embodiment, except that it is an annular body extending in the shape of a substantially perfect circle. The athletics track shape has two long sides extending parallel to each other in a substantially straight line, and two short sides connecting the long sides and extending in a semicircular curve. The core 1 has an inner peripheral surface 1a, an outer peripheral surface 1b, end faces 1c and 1d in the axial direction (here, the Z-axis direction), and a through hole 1e. The through hole 1e is formed by the inner peripheral surface 1a. The axial direction is the direction in which the axis of the through hole 1e (here, the Z axis) extends, and the axis is surrounded by the inner peripheral surface 1a of the core 1. The core 1 can be made using a wide variety of known core materials. Examples of the core material include ferrite materials, nanocrystalline alloy magnetic materials, and dust cores. Examples of the ferrite material include MnZn-based ferrite. The nanocrystalline alloy magnetic material is a soft magnetic material having nano-sized crystals inside an amorphous alloy.

[0020] The magnetic permeability of the core 1 is preferably equal to or greater than the magnetic permeability of the first magnetic body 2. The magnetic permeability of the core 1 is preferably equal to or greater than the magnetic permeability of the second magnetic body 3. When the magnetic permeability of the core 1 is equal to or greater than the magnetic permeability of the first magnetic body 2 or the magnetic permeability of the second magnetic body 3, the line filter 10 can ensure high common-mode inductance.

[0021] The first magnetic body 2 includes a first plate-shaped portion 2a and a first protruding portion 2c. The first magnetic body 2 according to this embodiment further includes a first protruding portion 2d. The first plate-shaped portion 2a is disposed inside the core 1 so that the main surfaces 2aa, 2ab of the first plate-shaped portion 2a are aligned in the axial direction. Specifically, the first plate-shaped portion 2a is disposed within the through-hole 1e so that the main surfaces 2aa, 2ab of the first plate-shaped portion 2a are aligned in the axial direction. The first protruding portions 2c, 2d protrude radially outward from one axial end portion 2b of the first plate-shaped portion 2a. Specifically, the first protruding portion 2c protrudes radially outward from the core 1 (here, in the negative Y-axis direction) from the front side of one axial end portion 2b of the first plate-shaped portion 2a (here, in the negative Y-axis direction). The first protrusion 2d protrudes from the rear side (here, the positive Y-axis direction) of one axial end 2b of the first plate-shaped portion 2a toward the radially outer side of the core 1 (here, the positive Y-axis direction). The protruding direction of the first protrusion 2d is opposite to the protruding direction of the first protrusion 2c. The protruding directions of the first protrusions 2c and 2d are substantially parallel to the main surfaces 2aa and 2ab. The tips of the first protrusions 2c and 2d are located on the outer peripheral surface 1b side of the core 1 from the inner peripheral surface 1a of the core 1. The tips of the first protrusions 2c and 2d are preferably located between the inner peripheral surface 1a of the core 1 and the outer peripheral surface 1b of the core 1, and more preferably, are located on the outer peripheral surface 1b of the core 1. In other words, the distance from the tip of the first protrusion 2c to the tip of the first protrusion 2d is preferably equal to or greater than the inner diameter and equal to or less than the outer diameter of the core 1, and more preferably equal to the outer diameter of the core 1. The inner diameter of the core 1 is the same as the diameter of the through hole 1e. The first plate-shaped portion 2a is spaced apart from the inner peripheral surface 1a of the core 1. This ensures high differential mode inductance while reducing the risk of damage to the core 1 or the first magnetic body 2 during assembly of the line filter 10.

[0022] The first protrusion 2c according to this embodiment is spaced apart from the end face 1c of the core 1. Specifically, the first protrusion 2c has an opposing surface 2e facing the end face 1c of the core 1, and the opposing surface 2e is spaced apart from the end face 1c. The first plate-shaped portion 2a has an opposing end face 2g facing the inner peripheral surface 1a of the core 1 along the axial direction, and the opposing end face 2g is spaced apart from the inner peripheral surface 1a. The distance L21 between the opposing surface 2e and the end face 1c is shorter than the distance L12 between the opposing end face 2g and the inner peripheral surface 1a. Furthermore, the first protrusion 2d according to this embodiment is spaced apart from the end face 1c of the core 1. Specifically, the first protrusion 2d has an opposing surface 2f facing the end face 1c of the core 1, and the opposing surface 2f is spaced apart from the end face 1c. The distance L22 between the opposing surface 2f and the end face 1c is shorter than the distance L12. These measures make it possible to further ensure differential mode inductance and reduce the risk of damage to the core 1 and the first magnetic body 2.

[0023] The second magnetic body 3 includes a second plate-shaped portion 3a and a second protruding portion 3c. The second magnetic body 3 according to this embodiment further includes a second protruding portion 3d. The second plate-shaped portion 3a is disposed inside the core 1 so that the main surfaces 3aa, 3ab of the second plate-shaped portion 3a are aligned in the axial direction. Specifically, the second plate-shaped portion 3a is disposed within the through-hole 1e so that the main surfaces 3aa, 3ab of the second plate-shaped portion 3a are aligned in the axial direction. The second protruding portions 3c, 3d protrude radially outward from one axial end portion 3b of the second plate-shaped portion 3a. Specifically, the second protruding portion 3c protrudes radially outward from the core 1 (here, in the negative Y-axis direction) from the front side (here, in the negative Y-axis direction) of one axial end portion 3b of the second plate-shaped portion 3a. The second protrusion 3d protrudes from the rear side (here, the positive Y-axis direction) of one axial end 3b of the second plate-shaped portion 3a toward the radially outer side of the core 1 (here, the positive Y-axis direction). The protruding direction of the second protrusion 3d is opposite to the protruding direction of the second protrusion 3c. The protruding directions of the second protrusions 3c, 3d are approximately parallel to the main surfaces 3aa, 3ab. The tips of the second protrusions 3c, 3d are preferably located between the inner circumferential surface 1a of the core 1 and the outer circumferential surface 1b of the core 1, more preferably located on the outer circumferential surface 1b of the core 1. In other words, the distance from the tip of the second protrusion 3c to the tip of the second protrusion 3d is preferably equal to or greater than the inner diameter and equal to or less than the outer diameter of the core 1, more preferably equal to the outer diameter of the core 1. The inner diameter of the core 1 is equal to the diameter of the through hole 1e. The second plate-shaped portion 3a and the inner circumferential surface 1a of the core 1 are spaced apart. These features make it possible to ensure a high differential mode inductance and further reduce the risk of damage to the core 1 and the second magnetic body 3 when assembling the line filter 10.

[0024] In this embodiment, the other axial end 2h of the first plate-shaped portion 2a and the other axial end 3h of the second plate-shaped portion 3a are opposed to and spaced apart from each other, but the other end 2h and the other end 3h may be in contact with each other.

[0025] The second protrusion 3c according to this embodiment is spaced apart from the end face 1d of the core 1. Specifically, the second protrusion 3c has an opposing surface 3e facing the end face 1d of the core 1, and the opposing surface 3e is spaced apart from the end face 1d. The second plate-shaped portion 3a has an opposing end face 3g facing the inner circumferential surface 1a of the core 1 along the axial direction, and the opposing end face 3g is spaced apart from the inner circumferential surface 1a. A distance L31 between the opposing surface 3e and the end face 1d is shorter than a distance L13 between the opposing end face 3g and the inner circumferential surface 1a. Furthermore, the second protrusion 3d according to this embodiment is spaced apart from the end face 1d of the core 1. Specifically, the second protrusion 3d has an opposing surface 3f facing the end face 1d of the core 1, and the opposing surface 3f is spaced apart from the end face 1d. A distance L32 between the opposing surface 3f and the end face 1d is shorter than the distance L13. These make it possible to ensure high differential mode inductance and further reduce the risk of damage to the core 1 and the second magnetic body 3.

[0026] The first protrusion 2c and the end face 1c may be in contact. Similarly, the first protrusion 2d and the end face 1c may be in contact. The second protrusion 3c and the end face 1d may be in contact. The second protrusion 3d and the end face 1d may be in contact. These arrangements ensure a higher differential mode inductance.

[0027] Alternatively, a plate-like body may be provided between the opposing end face 2g and the inner peripheral surface 1a. Alternatively, the plate-like body may be provided between the opposing end face 3g and the inner peripheral surface 1a. The hardness of the plate-like body is preferably lower than the hardness of the core 1, the first magnetic body 2, and the second magnetic body 3. For example, the plate-like body may be made of an insulating material such as resin or rubber, or may contain a magnetic material.

[0028] As shown in FIG. 3 , the case 4 houses the core 1, the first magnetic body 2, and the second magnetic body 3. The case 4 covers the core 1, the first magnetic body 2, and the second magnetic body 3. The case 4 has an upper opening 4a and a lower opening 4b. The upper opening 4a opens to the upper side (here, in the positive direction of the Z axis). When the core 1 and the first magnetic body 2 are housed in the case 4, the core 1 and the first magnetic body 2 are preferably exposed from the upper opening 4a. The lower opening 4b opens to the lower side (here, in the negative direction of the Z axis). More specifically, the portion of the case 4 where the second magnetic body 3 is disposed is open to the lower side. When the core 1 and the second magnetic body 3 are housed in the case 4, the second magnetic body 3 is preferably exposed from the lower opening 4b.

[0029] The first cover 5 is attached near the upper opening 4a of the case 4. The first cover 5 closes the upper opening 4a and covers the core 1 and the first magnetic body 2. The first cover 5 is preferably bonded to the first magnetic body 2 with an adhesive to hold the first magnetic body 2.

[0030] The second cover 6 is attached near the lower opening 4b of the case 4. The second cover 6 closes the lower opening 4b and covers the second magnetic body 3. The second cover 6 may be bonded to the second magnetic body 3 with an adhesive to hold the second magnetic body 3 in place.

[0031] The case 4, the first cover 5, and the second cover 6 are made of, for example, an insulating material. The insulating material is a material that has electrical insulating properties, such as a plastic resin. Specific examples of the plastic resin include PBT (polybutylene terephthalate), PET (polyethylene terephthalate), and polyamide.

[0032] The windings 7 and 8 shown in FIG. 1 may be electrically conductive wires, such as copper wires or enamel-coated wires. The winding 7 according to this embodiment is wound in one area of ​​the case 4, the first cover 5, and the second cover 6. The winding 8 according to this embodiment is wound in another area of ​​the case 4, the first cover 5, and the second cover 6, with a predetermined distance from the winding 7. The line filter 10 may include two bus bars. These two bus bars may be inserted between the core 1 and the first magnetic body 2. Specifically, one of the two bus bars is inserted between the inner circumferential surface 1a of the core 1 and the main surface 2aa of the first plate-shaped portion 2a of the first magnetic body 2. The other of the two bus bars is inserted between the inner circumferential surface 1a of the core 1 and the main surface 2ab of the first plate-shaped portion 2a of the first magnetic body 2.

[0033] As described above, according to the configuration of the line filter 10, a magnetic path is generated along the core 1, the first magnetic body 2, and the second magnetic body 3. This ensures high differential mode inductance. Furthermore, because the first plate-shaped portion 2a and the inner peripheral surface 1a of the core 1 are spaced apart, damage to the core 1 due to contact between the components during assembly of the core 1, the first magnetic body 2, and the second magnetic body 3 can be prevented. Furthermore, the distance between the components is specified, such as the space between the first plate-shaped portion 2a and the inner peripheral surface 1a of the core 1. This allows for efficient adjustment of leakage flux and magnetic flux flow, thereby suppressing magnetic saturation. In other words, this ensures high differential mode inductance while reducing the risk of damage to the core 1.

[0034] In known line filters, magnetic flux caused by differential mode currents tends to escape to the outside of the line filter. Therefore, when known line filters are placed near a metal body, the differential mode inductance often decreases. When the line filter 10 is placed near the metal body, the decrease in differential mode inductance can be suppressed. An electronic device may include the line filter 10. Specifically, the electronic device includes a substrate and a metal housing. The substrate mounts the line filter 10. The substrate is housed in the metal housing. When the line filter 10 is placed near the metal housing, the decrease in differential mode inductance can be suppressed. [Example]

[0035] Next, with reference to Figs. 7 to 10, calculation results of magnetic properties for an example of the line filter 10 will be described. Fig. 7 is a perspective view showing an example of a line filter arranged between metal plates. Fig. 8 is a perspective view showing another example of a line filter arranged between metal plates. Fig. 9 is a diagram showing magnetic flux distribution in a cross section of the line filter taken along each cutting line. Fig. 10 is a diagram showing an example of magnetic flux distribution around the line filter.

[0036] Similar to the line filter 10 shown in FIG. 1, magnetic characteristics were calculated for an example of the line filter 10 in which no metal plates were disposed around the filter. Magnetic characteristics were also calculated for the example of the line filter 10 shown in FIGS. 7 and 8. The magnetic characteristics include magnetic flux distribution and differential mode inductance. In the example of the line filter 10 shown in FIG. 7, metal plate P1 is disposed above the line filter 10, and metal plate P2 is disposed below the line filter 10. In the example of the line filter 10 shown in FIG. 8, metal plate P3 is disposed in front of the line filter 10, and metal plate P4 is disposed behind the line filter 10. The metal plates P1 to P4 are made of an aluminum alloy. The dimensions of the metal plates P1 to P4 are 68 mm wide, 68 mm long, and 4 mm thick. The distance between the metal plate P1 and the windings 7 and 8 is 7.5 mm. Similarly, the distance between the metal plate P2 and the windings 7 and 8, the distance between the metal plate P3 and the windings 7 and 8, and the distance between the metal plate P4 and the windings 7 and 8 are also 7.5 mm. The current frequency was set to 10 kHz or 100 kHz. The magnetic properties of each example were calculated using known electromagnetic field analysis software.

[0037] The line filter according to the comparative example has the same configuration as the line filter 10, except that it does not have the first magnetic body 2 and the second magnetic body 3. As with the line filter 10 shown in FIG. 1, the magnetic characteristics were calculated for the line filter according to the comparative example in which no metal plates were arranged around the filter. As with the example of the line filter 10 shown in FIG. 7, the magnetic characteristics were calculated for the line filter according to the comparative example in which metal plates P1 and P2 were arranged above and below the filter. Furthermore, as with the example of the line filter 10 shown in FIG. 8, the magnetic characteristics were calculated for the line filter according to the comparative example in which metal plates P3 and P4 were arranged before and after the filter.

[0038] As shown in FIG. 9, in the cross section of the line filter 10 of the embodiment taken along the cutting line IV-IV, the magnetic flux density is high at the boundary between the core 1 and the first protruding portion 2c. The magnetic flux density is also high at the boundary between the core 1 and the first protruding portion 2d. The magnetic flux density is also high at the boundary between the core 1 and the second protruding portion 3c. The magnetic flux density is also high at the boundary between the core 1 and the second protruding portion 3d. The cross section of the line filter 10 taken along the cutting line IV-IV is parallel to the main surfaces 2aa and 2ab shown in FIG. 3. The cross section of the line filter 10 taken along the cutting line IV-IV includes the core 1, the first plate-shaped portion 2a, the first protruding portions 2c and 2d, the second plate-shaped portion 3a, and the second protruding portions 3c and 3d. The cross section of the line filter 10 taken along the cutting line IVA-IVA is a plane perpendicular to the protruding direction of the first protruding portions 2c and 2d. The cross section of the line filter 10 taken along the cutting line IVA-IVA includes the core 1, the first plate-shaped portion 2a, and the second plate-shaped portion 3a. Furthermore, in the cross section of the line filter 10 taken along the cutting line IVA-IVA, the magnetic flux density of the core 1 is high and uniformly distributed, while the magnetic flux densities of the first plate-shaped portion 2a and the second plate-shaped portion 3a are lower than the magnetic flux density of the core 1 and uniformly distributed. Furthermore, in the cross section of the line filter 10 taken along the cutting line IVB-IVB, the magnetic flux density of the core 1 is high and uniformly distributed, while the magnetic flux densities of the first plate-shaped portion 2a and the second plate-shaped portion 3a decrease from the one end 2b, 3b side toward the other end 2h, 3h side and are lower than the magnetic flux density of the core 1. This indicates that the magnetic permeability of the core 1 should preferably be equal to or higher than that of the first magnetic body 2. Furthermore, in the cross section of line filter 10 taken along cutting line IVA-IVA, the DC superposition characteristics of the differential mode inductance are improved if the sum of the cross-sectional areas of first plate-shaped portion 2a and second plate-shaped portion 3a is at least twice the cross-sectional area of ​​core 1. Here, even if core 1 wound with windings 7 and 8 experiences magnetic saturation due to current flow, first plate-shaped portion 2a and second plate-shaped portion 3a will still contribute to the differential mode inductance.In addition, even if magnetic saturation occurs partially in the area of ​​high magnetic flux density due to the DC superimposed current, magnetic saturation does not occur easily near the other ends 2h, 3h of the first plate-shaped portion 2a and the second plate-shaped portion 3a, particularly, and a minimum differential mode inductance is ensured, resulting in so-called soft magnetic saturation, which has the advantage of maintaining functionality when used as an inductor for a DC / DC converter, for example. While this embodiment includes the first magnetic body 2 and the second magnetic body 3, it may also include only the first magnetic body 2. In this case, the other end 2h of the first plate-shaped portion 2a is preferably located near the end face 1d of the core 1, and the cross-sectional area of ​​the first plate-shaped portion 2a is preferably at least twice the cross-sectional area of ​​the core 1.

[0039] As can be seen from the magnetic field distribution around the line filter without a metal plate, the line filter 10 of the example has a lower ratio of leakage magnetic flux to the total generated magnetic flux compared to the line filter of the comparative example. Furthermore, the magnetic field inside the line filter 10 of the example is stronger than the magnetic field inside the line filter of the comparative example. The magnetic field is particularly strong near the inner circumferential surface of the core 1 of the example. Furthermore, in the comparative example, the magnetic field maintains a continuously high value from the core 91 to the metal plates P3 and P4, and the influence of the metal plates P3 and P4 is significant. In the example, the magnetic field decreases from the core 1 to the metal plates P3 and P4, then increases, and the high values ​​are not continuous. The influence of the metal plates P3 and P4 in the example is smaller than the influence of the metal plates P3 and P4 in the comparative example.

[0040] Table 1 shows the reduction rate of differential mode inductance due to the arrangement of metal plates when the current frequency is 10 kHz. As shown in Table 1, the reduction rate of differential mode inductance in the example is lower than that in the comparative example. In the example, magnetic flux is not generated much outside the line filter 10, but is generated inside the line filter 10, specifically in the core 1, the first magnetic body 2, and the second magnetic body 3. Therefore, it is presumed that the reduction in differential mode inductance due to the arrangement of metal plates was small in the example. [Table 1]

[0041] (Manufacturing method) Next, a method for manufacturing the line filter 10 will be described with reference to Figures 11 and 12. Figures 11 and 12 are schematic diagrams showing the method for manufacturing the line filter according to the first embodiment.

[0042] As shown in FIG. 11, an adhesive such as silicone is applied to areas A41, A42, A43, and A44 on the inner bottom surface 4c of the case 4 (step ST1). Then, the core 1 is housed in the case 4 (step ST2). Here, the core 1 and the case 4 are bonded to each other via the adhesive. Then, the second magnetic body 3 is placed inside the lower opening 4b of the case 4 (step ST3). Here, the second plate-shaped portion 3a is placed inside the core 1 so that the main surface of the second plate-shaped portion 3a is aligned along the axial direction (here, the Z-axis direction).

[0043] Next, as shown in FIG. 12, the second cover 6 is placed in the lower opening 4b of the case 4 (step ST4). After applying adhesive to one axial end 3b of the second plate-shaped portion 3a of the second magnetic body 3 and to areas A61, A62, and A63 on the second protrusions 3c and 3d, respectively, the second cover 6 is placed in the lower opening 4b. The second magnetic body 3 and the second cover 6 are bonded to each other via the adhesive. Note that in step ST4, the adhesive may be applied to areas on the second magnetic body 3 other than areas A61, A62, and A63. Even if the adhesive is applied to these areas, the adhesion between the second magnetic body 3 and the second cover 6 can be sufficiently maintained.

[0044] Next, the first magnetic body 2 is placed in the upper opening 4a of the case 4 (step ST5). Next, the first cover 5 is placed in the upper opening 4a of the case 4 (step ST6). Specifically, adhesive is applied to the axial end 2b of the first plate-shaped portion 2a of the first magnetic body 2 and to regions A51, A52, and A53 on the first protrusions 2c and 2d. Silicone adhesive is also applied to regions A54, A55, and A56 on the end surface 1c of the core 1. Thereafter, the first cover 5 is placed in the upper opening 4a. The first magnetic body 2 and the first cover 5 are bonded to each other via the adhesive. The core 1 and the first cover 5 are also bonded to each other via the adhesive. Note that in this step ST6, it is sufficient that the first magnetic body 2 and the first cover 5 are sufficiently bonded to each other; the adhesive may be applied to locations on the first magnetic body 2 other than the regions A51, A52, and A53. Even if an adhesive is applied to this portion, the adhesion between the first magnetic body 2 and the first cover 5 can be sufficiently maintained.

[0045] 1 are wound around the case 4, the first cover 5, and the second cover 6 (step ST7). In this way, the line filter 10 can be manufactured.

[0046] The present invention is not limited to the above-described embodiment and can be modified as appropriate without departing from the spirit and scope of the present invention. Furthermore, the present invention may be embodied by appropriately combining the above-described embodiment and examples thereof. For example, in steps ST1 and ST2 of the method for manufacturing the line filter 10 shown in FIGS. 11 and 12, the core 1 and the case 4 are bonded together using an adhesive. However, the first cover 5 and the second cover 6 may be attached to the case 4 using a snap-fit ​​mechanism, and the core 1 may be housed in the case 4. [Explanation of symbols]

[0047] 10 Line Filter 1, 21 cores 1a, 21a Inner surface 1b, 21b outer surface 1c, 21c end face (one end side end face) 1d, 21d end face (other end end face) 1e Through hole 2. First magnetic material 2a First plate-shaped portion 2aa, 2ab main surface 2b One end 2c, 2d First protrusion 2e, 2f opposing surfaces 2g Opposite end 2h Other end 3 Second magnetic material 3a Second plate-shaped portion 3aa, 3ab main surfaces 3b One end 3c, 3d Second protrusion 3e, 3f facing side 3g Opposite end face 3h Other end 4 cases 4a Upper opening 4b Lower opening 5 First Cover 6 Second Cover 6a Inner main surface 7, 8 windings P1, P2, P3, P4 metal plate A41~A44, A51~A56, A61~A63 area

Claims

1. an annular core; a first magnetic body; When the direction in which the shaft around which the annular core extends is defined as the axial direction, the core includes an inner peripheral surface, an outer peripheral surface, an end face on one end side in the axial direction, and an end face on the other end side in the axial direction, the first magnetic body includes a first plate-shaped portion and a first protrusion, the first plate-shaped portion is disposed inside the core such that a main surface of the first plate-shaped portion is aligned along the axial direction; the first protruding portion protrudes radially outward from one end of the first plate-shaped portion in the axial direction, a tip end of the first protrusion is located from the inner circumferential surface of the core toward the outer circumferential surface of the core, The first plate-shaped portion and the inner circumferential surface of the core are spaced apart from each other. Line filter.

2. the first protrusion and an end surface of the core on one end side in the axial direction are spaced apart from each other; 2. The line filter according to claim 1.

3. the first protrusion has an opposing surface that faces one end surface of the core in the axial direction, the first plate-shaped portion has an opposing end surface that faces the inner circumferential surface of the core along the axial direction, a distance between the opposing surface of the first protrusion and one end face of the core in the axial direction is shorter than a distance between the opposing end face of the first plate-shaped portion and the inner circumferential surface of the core; 3. The line filter according to claim 1 or 2.

4. The magnetic permeability of the core is equal to or greater than the magnetic permeability of the first magnetic body.

3. The line filter according to claim 1 or 2.

5. The line filter according to claim 1 or 2; A substrate; a metal housing; The substrate is provided with the line filter according to claim 1 or 2, The substrate is housed in the metal housing. electronic equipment.

6. Further comprising a second magnetic body, the second magnetic body includes a second plate-shaped portion and a second protrusion, the second plate-shaped portion is disposed inside the core such that a main surface of the second plate-shaped portion is aligned along the axial direction, the second protruding portion protrudes from one end of the second plate-shaped portion in the axial direction toward the outside in the radial direction of the core, a tip end of the second protrusion is located from the inner circumferential surface of the core toward the outer circumferential surface of the core, The second plate-shaped portion and the inner circumferential surface of the core are spaced apart from each other.

3. The line filter according to claim 1 or 2.

7. In a cross section perpendicular to the protruding direction of the first protruding portion, the cross-sectional area of ​​the first magnetic body is at least twice the cross-sectional area of ​​the core.

3. The line filter according to claim 1 or 2.

8. In a cross section perpendicular to the protruding direction of the first protruding portion, the sum of the cross-sectional area of ​​the first magnetic body and the cross-sectional area of ​​the second magnetic body is at least twice the cross-sectional area of ​​the core.

7. The line filter according to claim 6.

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