Magnetic core and coil device

Abstract

To improve the performance of a coil device having a magnetic core in which a magnetic gap in the form of a gap hole is formed.SOLUTION: A magnetic core according to an embodiment of the present invention includes a yoke portion and a leg portion having one end connected to one surface of the yoke portion, and a V-shaped gap hole is formed across the boundary between the yoke portion and the leg portion. A magnetic core according to another embodiment of the present invention includes a yoke portion and a middle leg portion having one end connected to one surface of the yoke portion, and a V-shaped gap hole is formed at one end portion of the middle leg portion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a magnetic core and a coil device. [Background technology]

[0002] Among coil devices such as reactors that have a magnetic core (hereinafter referred to as a "core"), those that have a gapped magnetic core (hereinafter referred to as a "gap core") are known. Patent Documents 1 and 2 describe examples of coil devices that have a gap core.

[0003] In the gap core described in Patent Document 1, a magnetic gap is provided between the C-type laminated core 3 and the I-type laminated core 2 by connecting the C-type laminated core 3 and the I-type laminated core 2 via a spacer 4.

[0004] The gap core described in Patent Document 1 is made by joining multiple core members via spacers, which results in a large number of parts and a complicated assembly process. In addition, the use of spacers makes it difficult to shorten the gap length.

[0005] Patent Document 2 describes a gap core in which a magnetic gap is provided by laminating silicon steel plates in which linear elongated holes (gap holes 22) that are perpendicular to the magnetic path are formed.

[0006] The gap core described in Patent Document 2 does not use a spacer, so the number of parts is small and the number of steps required for assembly is also small. In addition, it is relatively easy to shorten the gap length, and the gap length can be determined with high accuracy, resulting in little variation in characteristics (individual differences). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2019-71358 [Patent Document 2] Japanese Patent Publication No. 2021-44338 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the coil device in which a magnetic gap is provided in the core by the gap hole described in Patent Document 2, magnetic flux is concentrated in the narrow parts (hereinafter referred to as the "bridge parts") on both sides 20Ad of the gap hole, so that magnetic flux is likely to leak from the bridge parts to the outside of the core, and there is also a large bias in the distribution of magnetic flux within the core, resulting in relatively low performance.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to improve the performance of a coil device having a core in which a magnetic gap is provided by a gap hole. [Means for solving the problem]

[0010] A magnetic core according to one embodiment of the present invention comprises a yoke portion and a leg portion having one end connected to one surface of the yoke portion, and a V-shaped gap hole formed across the boundary between the yoke portion and the leg portion.

[0011] In the magnetic core, both ends of the V-shaped gap hole may be located in the yoke portion, and the apex of the V-shaped gap hole may be located in the leg portion.

[0012] A magnetic core according to another embodiment of the present invention comprises a yoke portion and a center leg portion having one end connected to one surface of the yoke portion, and a V-shaped gap hole formed at one end of the center leg portion.

[0013] In the magnetic core, both ends of the V-shaped gap hole may be located at the boundary between the yoke portion and the center leg portion.

[0014] In the magnetic core, the apex of the V-shaped gap hole may be located at the boundary between the yoke portion and the center leg portion.

[0015] In the magnetic core described above, the gap hole may be configured to be symmetrical with respect to a center plane that is a plane including a center line extending in the length direction of the center leg portion.

[0016] In the magnetic core, the bridge width, which is the distance from the side surface of the center leg that is parallel to the center plane to the gap hole, may be in the range of 0.5 mm to 2.5 mm.

[0017] By setting the bridge width within the range of 0.5mm to 2.5mm, it is possible to obtain a good inductance improvement effect while reducing the reduction rate of the L value (L 2A -L 20A ) / L 2A can be kept low.

[0018] In the magnetic core, the V-shaped angle of the gap hole may be in the range of 30° to 120°.

[0019] By setting the V-shaped angle of the gap hole within the range of 30° to 120°, it is possible to obtain a good inductance improvement effect while reducing the reduction rate of the L value (L 2A -L 20A ) / L 2A can be kept low.

[0020] The above-mentioned magnetic core may be a laminated magnetic core consisting of a plurality of stacked core plates, with an element gap hole formed in each core plate, and the element gap holes of the stacked core plates may be connected to form a gap hole.

[0021] A coil device according to one embodiment of the present invention includes a coil and the above-described magnetic core, with the center leg portion inserted into the coil. [Effects of the Invention]

[0022] According to one embodiment of the present invention, in a coil device in which a magnetic gap is provided in a core by a gap hole, the concentration of magnetic flux in a bridge portion is alleviated, improving performance. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is an external view of a coil device according to an embodiment of the present invention; [Figure 2] FIG. 2 is an exploded view of the coil device according to the embodiment of the present invention. [Figure 3] FIG. 2 is a front view of a core according to an embodiment of the present invention. [Figure 4] FIG. 10 is a perspective view of a die for punching V-shaped gap holes from a core plate. [Figure 5] 10A and 10B are diagrams showing how a magnetic resin is filled into a gap hole. [Figure 6] FIG. 10 is a magnetic flux density distribution diagram of Example 1 obtained by simulation. [Figure 7] FIG. 10 is a magnetic flux density distribution diagram of Example 2 obtained by simulation. [Figure 8] FIG. 10 is a magnetic flux density distribution diagram of Comparative Example 1 obtained by simulation. [Figure 9] FIG. 10 is a magnetic flux density distribution diagram of Comparative Example 2 obtained by simulation. [Figure 10] FIG. 10 is a magnetic flux density distribution diagram of Comparative Example 3 obtained by simulation. [Figure 11] FIG. 10 is a magnetic flux density distribution diagram of Comparative Example 4 obtained by simulation. [Figure 12] FIG. 10 is a magnetic flux density distribution diagram of Example 3 obtained by simulation. [Figure 13] FIG. 10 is a magnetic flux density distribution diagram of Example 4 obtained by simulation. [Figure 14] FIG. 10 is a magnetic flux density distribution diagram of Example 5 obtained by simulation. [Figure 15] FIG. 10 is a magnetic flux density distribution diagram of Example 6 obtained by simulation. [Figure 16] FIG. 10 is a magnetic flux density distribution diagram of Example 9 obtained by simulation. [Figure 17] FIG. 20 is a magnetic flux density distribution diagram of Example 10 obtained by simulation. [Figure 18]FIG. 10 is a magnetic flux density distribution diagram of Comparative Example 5 obtained by simulation. [Figure 19] FIG. 10 is a magnetic flux density distribution diagram of Comparative Example 6 obtained by simulation. [Figure 20] FIG. 10 is a magnetic flux density distribution diagram of Comparative Example 7 obtained by simulation. [Figure 21] 10A and 10B are diagrams illustrating the action of a V-shaped gap hole to guide magnetic flux. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same or corresponding items will be denoted by the same or corresponding reference numerals, and redundant description will be omitted.

[0025] Fig. 1 is an external view of a coil device 1 according to a first embodiment of the present invention. The coil device 1 of this embodiment is a reactor with a relatively large inductance value suitable for use at low frequencies. As shown in Fig. 1, the coil device 1 includes a coil 10 (winding) and a core 20 (magnetic core).

[0026] The coil 10 is formed by spirally winding an insulating-coated conductor wire, such as an enameled wire. The conductor wire is made of, for example, copper or aluminum. The coil 10 is formed by edgewise winding a rectangular wire, but it may also be formed from a round wire. The coil 10 may also be formed from a conductor in the form of a foil or strip, such as a copper foil coil or copper strip coil.

[0027] Fig. 2 is an exploded view of the coil device 1, and Fig. 3 is a front view of the core 20. As shown in Fig. 2, the core 20 is an EI core assembled from an E-shaped laminated core 20A (E core) made by stacking a plurality of core plates 20a, which are electromagnetic steel plates such as silicon steel plates, and an I-shaped laminated core 20B (I core) made by stacking a plurality of core plates 20b, which are also electromagnetic steel plates.

[0028] 2, the axial direction of the coil 10 is defined as the Z-axis direction, the lamination direction of the core plates 20a and 20b is defined as the X-axis direction, and the Y-axis direction is perpendicular to both the X-axis direction and the Z-axis direction.

[0029] Each core plate 20a, 20b is formed by punching out a plate-shaped conductor with a die. The thickness t of each core plate 20a, 20b is the same, for example, 0.5 mm. The laminated cores 20A, 20B are integrated by welding. The laminated cores 20A, 20B may be integrated by silver brazing or adhesive bonding, or by fastening with bolts passed through holes formed in the core plates. Each laminated core 20A, 20B may be simply stacked without fastening multiple core plates 20a, 20b together. The thickness t of each core plate 20a, 20b is not limited to 0.5 mm. For example, the thickness t of each core plate 20a, 20b may be 0.2 mm, 0.23 mm, 0.27 mm, 0.3 mm, 0.35 mm, 0.4 mm, or greater than 0.5 mm. The core 20 has, for example, a width W of 48 mm and a length L of 44 mm.

[0030] The core plate 20a has three legs extending in the Z-axis direction, specifically, one center leg 21a, a pair of outer legs 22a arranged side by side on both sides of the center leg 21a in the Y-axis direction, and a connecting portion 23a extending in the Y-axis direction that connects one end of the center leg 21a and the pair of outer legs 22a. The core plate 20b also has three legs extending in the Z-axis direction (i.e., one center leg 21b and a pair of outer legs 22b arranged side by side on both sides of the center leg 21b in the Y-axis direction), and a connecting portion 23b extending in the Y-axis direction that connects one end of the three legs. The center leg 21b and the outer legs 22b of the core plate 20b are significantly shorter than the connecting portion 23b, giving the core plate 20b an I-shape as a whole.

[0031] The center leg portions 21a, outer leg portions 22a, and connecting portion 23a of the core plate 20a are laminated to form the center leg portions 21A, outer leg portions 22A, and connecting portion 23A (yoke portion) of the laminated core 20A. The center leg portions 21b, outer leg portions 22b, and connecting portion 23b of the core plate 20b are laminated to form the center leg portions 21B, outer leg portions 22B, and connecting portion 23B (yoke portion) of the laminated core 20B.

[0032] Core 20 is formed by butting center leg 21A with center leg 21B and butting outer leg 22A with outer leg 22B, forming a magnetic path (more specifically, a closed magnetic path) for the magnetic flux generated by coil 10. The butted leg portions are fixed to each other by welding. The leg portions may be fixed by silver brazing or adhesive, or may be fixed using metal fittings (fixing devices), instead of welding.

[0033] The center leg portion 21A of the laminated core 20A and the center leg portion 21B of the laminated core 20B constitute the center leg portion 21 of the core 20, and the outer leg portion 22A of the laminated core 20A and the outer leg portion 22B of the laminated core 20B constitute the outer leg portion 22 of the core 20.

[0034] The core 20 is not limited to the configuration of this embodiment in which an E-shaped core and an I-shaped core are butted together, but may have other configurations such as a configuration in which U-shaped cores are butted together, a configuration in which a U-shaped core is butted together with an I-shaped core, a configuration in which E-shaped cores are butted together, etc. Also, an I-shaped laminated core 20B that does not have protruding portions such as short center legs 21B and outer legs 22B may be used.

[0035] In this embodiment, electromagnetic steel sheets such as silicon steel sheets are used for the core plates 20a and 20b, but other sheet materials such as non-ferrous metal alloys such as cobalt-based alloys or amorphous ribbons of iron-based alloys may also be used.

[0036] A V-shaped element gap hole 24a is formed in the center leg portion 21a of each core plate 20a. In the laminated core 20A, the element gap holes 24a of the stacked core plates 20a are connected to form a gap hole 24 that penetrates the laminated core 20A in the stacking direction (X-axis direction). The gap hole 24 has a structure that functions as a magnetic gap. In this embodiment, the gap hole 24 is formed in one end of the center leg portion 21A that is connected to one surface of the connecting portion 23A.

[0037] The gap hole 24 has a shape symmetrical with respect to the center plane C of the middle leg portion 21A (i.e., a plane perpendicular to the Y-axis direction that includes the center line extending in the longitudinal direction of the middle leg portion 21A), and has a slit portion 241 that extends in a V-shape with a certain width (hereinafter referred to as the "gap length G"), and a pair of round hole-shaped extension portions 242 formed at both ends of the slit portion 241.

[0038] By forming the gap hole 24 on a closed magnetic path, magnetic saturation is less likely to occur, and the inductance value can be ensured even in a high current band.

[0039] The narrower the gap length G of the gap hole 24 (i.e., the slit width of the slit portion 241), the more the inductance of the coil 10 can be increased. Therefore, narrowing the gap length G makes it easier to ensure the required inductance even when the volume of the laminated cores 20A and 20B (e.g., the length or width of the laminated cores 20A and 20B, or the number of laminated core plates 20a and 20b) is reduced or the number of turns of the coil 10 is reduced. Reducing the volume of the core 20 allows the core 20 to be made smaller, and the material cost of the core 20 can be kept low. Reducing the number of turns of the coil 10 allows the coil device 1 to be made smaller, and the material cost of the coil 10 can be kept low.

[0040] Therefore, in this embodiment, the gap length G is set to a value less than 1.6 times the plate thickness t of the core plate 20a. The gap length G is, for example, 0.7 mm.

[0041] To ensure inductance at the rated current while further reducing the volume of the laminated cores 20A and 20B, the gap length G may be in the range of 0.5 mm to less than 0.7 mm, or may be in the range of more than 0.7 mm and less than 0.8 mm.

[0042] The narrower the width of the slit portion 241, the thinner the mold used to punch the slit portion 241 from the core material needs to be made, which makes it difficult to ensure the durability of the mold and makes the mold more susceptible to breakage.

[0043] Therefore, in this embodiment, a pair of expansion portions 242 having a diameter 1.6 times or more the plate thickness t of the core plate 20a are formed at both ends of the slit portion 241. The diameter of the expansion portions 242 (hereinafter referred to as "gap length G'") is, for example, 1.5 mm.

[0044] 4 is a perspective view of a die 50 for punching gap holes 24 from core plate 20a. As shown in FIG. 4, die 50 has a thin plate portion 51 corresponding to slit portion 241. At both ends of thin plate portion 51, cylindrical portions 52 corresponding to each expansion portion 242 are formed. By forming cylindrical portions 52, both ends of thin plate portion 51, which are prone to breakage, are reinforced, and the durability of die 50 is improved.

[0045] In other words, by providing the extension portion 242, the thickness of the end portion (the portion corresponding to the extension portion 242) of the mold 50 for punching the gap hole 24 from the core material can be increased, thereby reinforcing the mold 50 and improving the durability of the mold 50. That is, the gap hole 24 has a hole shape suitable for improving the durability of the mold 50 by thickening both end portions of the thin plate portion 51 which is easily damaged.

[0046] The gap length G' is not limited to 1.5 mm, and may be any other value that is 1.6 times or more the thickness t of the core plate 20a (i.e., 0.8 mm or more). By setting the gap length G' to 1.6 times or more the thickness t, it is possible to ensure a sufficient thickness for the columnar portion 52 corresponding to the extension portion 242. This improves the durability of the mold 50, and makes it possible to prevent the mold 50 from breaking or bending. More specifically, since the columnar portion 52 serves to reinforce the entire mold 50, it is possible to prevent the mold 50 from breaking or bending even when the mold 50 has thin-walled portions.

[0047] In contrast, if the gap length G' is less than 1.6 times the plate thickness t of the core plate 20a, it is not possible to ensure a sufficient thickness for the cylindrical portion 502, and it is not possible to sufficiently improve the durability of the die 50. Therefore, the die 50 is prone to breakage or bending due to the repeated loads that it receives when punching out the core plate 20a.

[0048] If the die 50 has any acute angled parts, those parts are likely to chip due to the repeated loads that the die 50 receives when punching out the core plate 20a. Therefore, the connection part between the slit part 241 and the expansion part 242 is curved with a curvature radius of 0.1 mm.

[0049] The connecting portion between the slit portion 241 and the expansion portion 242 may have a rounded corner shape with a curvature radius of more than 0.1 mm. In this case, the corners of the mold 50 can be made more rounded, which is more suitable for improving the durability of the mold 50.

[0050] Moreover, the bent portion 241c of the slit portion 241 is also formed by a curved surface having a radius of curvature greater than 0.1 mm. Therefore, the bent portion 51c of the thin plate portion 51 of the mold 50 corresponding to the bent portion 241c is also formed by a curved surface having a radius of curvature greater than 0.1 mm.

[0051] As a result, the gap hole 24 has a hole shape that does not have any acute-angled portions. By forming the gap hole 24 in this way, the mold 50, which is prone to reduced durability due to its thin plate shape, can be made to have a shape that does not have any acute-angled portions. Such a shape of the gap hole 24 can eliminate from the mold 50 any acute-angled portions that are particularly prone to breakage due to its thin plate shape, and is therefore suitable for improving the durability of the mold 50 (in other words, preventing damage to the acute-angled portions due to the above-mentioned repeated loads).

[0052] The gap holes 24 of the core 20 are filled with magnetic resin 30, which is made by adding resin to magnetic powder. Fig. 5 shows how the magnetic resin 30 is filled into the gap holes 24 of the core 20.

[0053] The magnetic resin 30 is, for example, a material in which magnetic powder (more specifically, soft magnetic powder) is dispersed in a resin material. Resin materials used for the magnetic resin 30 include materials that can be cured from a liquid state to a solid state, such as thermosetting resins, ultraviolet-curing resins, and thermoplastic resins. Examples of soft magnetic powders used for the magnetic resin 30 include pure iron, Fe-based alloy powders such as Fe-Si, Fe-Ni, Fe-Al, Fe-Co, Fe-Cr, Fe-N, Fe-C, Fe-B, Fe-P, and Fe-Al-Si, rare earth metal powders, amorphous metal powders, ferrite powders, and mixtures of multiple types of powders. Alternatively, soft magnetic powders with an insulating coating may be used for the magnetic resin 30. Forming an insulating coating on the soft magnetic powder can reduce eddy current loss.

[0054] The amount of resin added to the soft magnetic powder is within the range of 3 wt% to 7 wt%. If the amount of resin added is less than 3 wt%, the bonding strength of the soft magnetic powder will be insufficient, and the strength of the obtained soft magnetic composite material will decrease. If the amount of resin added exceeds 7 wt%, the density of the soft magnetic composite material will decrease.

[0055] The magnetic resin 30 contains a large amount of soft magnetic powder to improve the effective magnetic permeability, and is in a liquid state with a relatively high viscosity before hardening. Consider, for example, a case in which the magnetic resin 30 is uniformly applied to the inside of the gap hole 24 during manufacturing. In this case, since the magnetic resin 30 has a high viscosity, it is difficult to apply the magnetic resin 30 uniformly to the inside of the gap hole 24.

[0056] For this reason, this embodiment employs a process of filling the gap holes 24 with magnetic resin 30. The gap holes 24 define spaces surrounded on all sides, and it is easy to uniformly pour the magnetic resin 30 into the gap holes 24 to fill them.

[0057] As shown in Fig. 5, magnetic resin 30 is injected into gap hole 24 using jig 60 (specifically, a syringe filled with magnetic resin 30). As shown in Fig. 5, extension portion 242 has dimensions that allow injection port 62 of jig 60 to reliably fit therein. Even if injection port 62 cannot fit into slit portion 241 because the width of slit portion 241 (i.e., gap length G) is formed to be narrow, magnetic resin 30 can be reliably injected into gap hole 24 from extension portion 242. That is, in this embodiment, it is not necessary to take the size of injection port 62 into consideration when setting gap length G.

[0058] The effective permeability varies depending on the gap length G. However, there are cases where the effective permeability cannot be set to a desired value by adjusting the gap length G alone. In this embodiment, by filling the gap hole 24 with magnetic resin 30, the effective permeability can be finely adjusted to match the desired value. By finely adjusting the effective permeability to match the desired value, for example, the DC bias characteristics are improved, making magnetic saturation less likely to occur.

[0059] Filling the gap hole 24 with the magnetic resin 30 improves the rigidity of the core 20 around the gap hole 24. As a result, vibration of the core 20 caused by the electromagnetic attraction force generated within the gap hole 24 and the noise associated with this vibration are kept low.

[0060] Furthermore, by filling the gap holes 24 with the magnetic resin 30, the magnetic flux leaking from the gap holes 24 is reduced, thereby reducing the occurrence of eddy current loss in the coil 10. For example, when the coil device 1 is mounted on a three-phase reactor, the reduction in the magnetic flux leaking from the gap holes 24 suppresses variations in the characteristics of each phase due to manufacturing errors in the legs of the core 20.

[0061] Furthermore, in a three-phase reactor in which the gap completely separates the core (for example, Comparative Example 1 shown in FIG. 8 and described later), various variations accumulate in the process of combining multiple cores (for example, variations in gap length are the result of the accumulation of variations in core dimensions and assembly), which tends to cause variations in characteristics between phases. In contrast, when the gap hole 24 that does not completely separate the core is used, as in this embodiment, variations in gap length depend only on the dimensional accuracy of the gap hole 24, and therefore variations in characteristics between phases are suppressed compared to a configuration in which the gap completely separates the core.

[0062] Furthermore, by filling the gap hole 24 with the magnetic resin 30, magnetic flux also flows inside the gap hole 24 (in other words, in the magnetic resin 30). Therefore, the concentration of magnetic flux flowing in the bridge portion 20Ad (i.e., the core portion remaining on both sides of the gap hole 24 in the Y-axis direction) is alleviated, and heat generation in the core 20 is suppressed.

[0063] Next, the results of simulations of the characteristics performed on various examples and comparative examples of the present invention will be described. Table 1 shows a list of the configurations of the examples and comparative examples for which simulations were performed. Also, magnetic flux density distribution diagrams obtained by the simulations are shown in Figures 6 to 20.

[0064] [Table 1]

[0065] The cross-sectional areas of the center leg portion 21, the outer leg portion 22, and the connecting portion 23 of the core 20 used in the simulation were each 287.0 mm 2 , 143.5mm 2and 128.1 mm 2 The simulation was performed under the condition that the coil 10 had 70 turns. The magnetic flux density distribution diagrams in FIGS. 6 to 20 (as well as the characteristic values ​​shown in Tables 2 and 3 described below) are the simulation results when an effective current of 10 A was passed through the coil 10.

[0066] In all of Examples 1 to 2, 4 to 10 (and Comparative Examples 5 to 7), gap hole 24 is formed at the end in the longitudinal direction (Z-axis direction) of center leg portion 21A. Strictly speaking, both ends (for example, expansion portion 242) or the apex of the V shape (bent portion 241c) of gap hole 24 are formed at the boundary between center leg portion 21A and connecting portion 23A, and the other portions are formed at the end of center leg portion 21A.

[0067] In Examples 1, 4 to 10 (and Comparative Examples 5 to 7), gap hole 24 is formed with the V-shaped opening toward adjacent connecting portion 23A. In these configuration examples, both ends of V-shaped gap hole 24 (for example, expansion portion 242) are located at the boundary between center leg portion 21A and connecting portion 23A.

[0068] In Example 2, the gap hole 24 is formed in a V-shape that closes toward the adjacent connecting portion 23A, which is the opposite of Example 1. Therefore, the shape of the gap hole 24 in Example 2 is called an "inverted V." In Example 2, the apex of the V-shape of the gap hole 24 (bent portion 241c) is located at the boundary between the center leg portion 21A and the connecting portion 23A.

[0069] In the third embodiment, a V-shaped gap hole 24 is formed across the boundary between the middle leg portion 21A and the connecting portion 23A. Specifically, a pair of expansion portions 242 of the gap hole 24 are formed in the connecting portion 23A, and a bent portion 241c is formed in the middle leg portion 21A. More specifically, approximately half of the gap hole 24 is formed in the connecting portion 23A, and the remainder is formed in the connecting portion 23A.

[0070] Table 2 compares the inductance characteristics of Examples 1 and 2 and Comparative Examples 1 to 3 obtained by simulation.

[0071] Table 3 compares the inductance characteristics of Examples 1, 3 to 10 and Comparative Examples 2, 4, 5 to 9 obtained by simulation.

[0072] In Table 3, "L 2A " is the inductance value when an effective current of 2 A flows through the coil 10 (i.e., the initial inductance value), and "L 20A " is the inductance value (L value) when an effective current of 20 A flows through the coil 10. 2A -L 20A ) / L 2A " is the rate of decrease in L value from the initial inductance value when a high current (20 A) is superimposed.

[0073] [Table 2]

[0074] [Table 3]

[0075] It can be seen from Table 2 that when the gap structure is made up of gap holes 24 (Examples 1 and 2, Comparative Examples 2 and 3), higher inductance characteristics can be obtained than when the gap structure is made up of a normal gap structure that completely separates the core (Comparative Example 1). This is thought to be because, in the case of gap holes 24, magnetic flux flows via bridge portions 20Ad, which have a high magnetic permeability, making it easier for magnetic flux to flow through core 20 than when the gap structure is made up of a normal gap structure that does not have bridge portions 20Ad.

[0076] In Comparative Example 2 having a linear gap hole, as shown in Fig. 9, the magnetic flux density is lower at the center portion 23Ac of the connecting portion 23A to which the center leg portion 21A is connected, compared to Comparative Example 1 (Fig. 8) having a normal gap structure. This is thought to be because the magnetic flux avoids the gap hole, which has low magnetic permeability, and flows concentratedly in the bridge portion 20Ad, which has high magnetic permeability. This results in a large bias in the distribution of the magnetic flux, and deteriorates the inductance characteristics.

[0077] 6 (Example 1), the V-shaped gap hole 24 reduces the decrease in magnetic flux density at the center 23Ac of the connecting portion 23A compared to Comparative Example 2, which has a linear gap hole, resulting in higher inductance characteristics. This is thought to be because, as shown in FIG. 21, the V-shaped gap hole 24 is formed obliquely with respect to the magnetic path extending in the Z-axis direction, and the magnetic flux is guided by the gap hole 24 to the center of the middle leg 21A in the X-axis direction, making it easier to pass through the gap hole 24. In other words, the magnetic flux is attracted to the region 21Aa of the middle leg 21A surrounded by the V-shaped gap hole 24 (the shaded portion in FIG. 21), making it easier for the magnetic flux to pass through the gap hole 24.

[0078] Example 2 (FIG. 7) is provided with an inverted V-shaped gap hole 24. As in Example 1, Example 2 also exhibits the effect of the V-shaped gap hole 24 (i.e., the V-shaped gap hole 24 guides the magnetic flux toward the center in the Y-axis direction, making it easier for the magnetic flux to pass through the gap hole 24 and improving the inductance characteristics), and higher inductance characteristics are obtained compared to Comparative Example 2, which has a linear gap hole.

[0079] 7, in Example 2, the amount of magnetic flux leaking from the vicinity of bridge portion 20Ad to the outside of core 20 is greater than in Example 1, and therefore the inductance characteristics are lower than in Example 1. In Example 1, bridge portion 20Ad is adjacent to coupling portion 23A, and therefore magnetic flux does not leak from the vicinity of bridge portion 20Ad (or, even if it does leak, it is immediately attracted to coupling portion 23A), and less magnetic flux leaks from core 20, which is thought to result in higher inductance characteristics than in Example 2.

[0080] In Comparative Example 3 (FIG. 10), a V-shaped gap hole 24 is provided at the center of the center leg 21A in the longitudinal direction (Z-axis direction). As shown in Table 2, the inductance characteristics of Comparative Example 3 are lower than those of Examples 1 and 2, and are comparable to those of Comparative Example 2, which has a linear gap hole. As shown in FIG. 10, although the gap hole 24 has the effect of guiding magnetic flux to the center of the center leg 21A in the X-axis direction, there is more significant leakage of magnetic flux near the bridge portion 20Ad than in Example 2, which is thought to be the cause of the deterioration in inductance characteristics. The increase in leakage magnetic flux is thought to be due to the bridge portion 20Ad being far away from the connecting portion 23A, which means that the connecting portion 23A is hardly able to attract the leakage magnetic flux.

[0081] In Comparative Example 4 (FIG. 11), the gap hole 24 is formed in the connecting portion 23A. As shown in Table 3, the initial inductance value is large, but the reduction rate of the L value (L 2A -L 20A ) / L 2A If the reduction rate of the L value is large, it may have an adverse effect depending on the circuit operation, so the reduction rate of the L value is preferably 80% or less, and more preferably 76% or less.

[0082] As shown in FIG. 11, in Comparative Example 4, the amount of magnetic flux passing through the center portion 23Ac of the connecting portion 23A (i.e., passing through the gap hole 24) is extremely small. In Comparative Example 4, since the cross-sectional area of ​​the bridge portion 20Ad is large, most of the magnetic flux bypasses the gap hole 24 and passes through the bridge portion 20Ad. That is, in Comparative Example 4, the effect of suppressing magnetic saturation by the gap hole 24 is weakened, which is the reason for the decrease in the L value (L 2A -L 20A ) / L 2A This is thought to be a factor that increases

[0083] As described above, in Example 3 (FIG. 12), the V-shaped gap hole 24 is formed across the boundary between the center leg portion 21A and the connecting portion 23A. That is, in Example 3, the position of the gap hole 24 is intermediate between that of Example 1 (FIG. 6) and Comparative Example 4 (FIG. 11). The characteristics of Example 3 are also intermediate between those of Example 1 and Comparative Example 4. In Example 3, the cross-sectional area of ​​the bridge portion 20Ad is smaller than that of Comparative Example 4, and therefore the magnetic flux detouring to the bridge portion 20Ad is also reduced, and the reduction rate of the L value is suppressed to 80% or less.

[0084] In Examples 4 to 6, only the angle θ (FIG. 3) of the V-shape of the gap hole 24 is changed from Example 1. From Table 3, it can be confirmed that a sufficient inductance improvement effect can be obtained with the gap hole 24 at any angle θ (30°≦θ≦120°). In addition, the smaller the angle θ, the greater the reduction rate of the L value (L 2A -L 20A ) / L 2A However, the rate of decrease in L value is less than 80% at any angle θ, and generally good inductance characteristics can be obtained within the range of 30° to 120°. A more desirable range for the angle θ is 60° to 120°, where the rate of decrease in L value is 76% or less.

[0085] In Examples 7 to 10 and Comparative Examples 5 to 7, only the bridge width Wd is changed from Example 1. As shown in the enlarged view of FIG. 3, the bridge width Wd is the distance in the Y-axis direction from the side surface of the center leg 21A perpendicular to the Y-axis direction (i.e., parallel to the center plane C of the center leg 21A) to the gap hole 24. From Table 3, it can be confirmed that a sufficient inductance improvement effect can be obtained with any bridge width Wd (0.5 mm≦Wd≦4.0 mm). The larger the bridge width Wd, the greater the inductance improvement effect, but at the same time, the rate of decrease in the L value (L 2A -L 20A ) / L 2A The decrease in the L value also increases. To suppress the decrease in the L value, it is desirable to narrow the bridge width Wd as much as possible. However, if the bridge width Wd is thinner than 0.5 mm, it becomes difficult to ensure mechanical strength, so the bridge width Wd is preferably 0.5 mm or more. Furthermore, if the bridge width Wd is thinner than 1.5 mm, it becomes difficult to process the element gap holes 24a, increasing the processing cost. Therefore, it is more desirable to set the bridge width Wd to 1.5 mm or more. Furthermore, it is desirable for the bridge width Wd to be 2.5 mm or less, at which the decrease in the L value is 80% or less. A more desirable range for the bridge width Wd is 2.0 mm or less, at which the decrease in the L value is 76% or less.

[0086] Furthermore, Table 3 confirms that Example 7 (Wd = 0.5 mm), Example 8 (Wd = 1.0 mm), and Example 1 (Wd = 1.5 mm) have improved initial inductance values ​​compared to Comparative Example 8 (Wd = 0.5 mm), Comparative Example 9 (Wd = 1.0 mm), and Comparative Example 2 (Wd = 1.5 mm), which each have the same bridge width Wd and a linear gap formed.

[0087] Although the above is a description of the embodiments of the present invention, the present invention is not limited to the configurations of the above embodiments and various modifications are possible within the scope of the technical concept. For example, an appropriate combination of at least a part of the technical configurations of one or more embodiments described in the specification with a well-known technical configuration is also included in the embodiments of the present invention.

[0088] In the above embodiment, the gap hole 24 is formed in the center leg portion 21, but it may also be formed in the outer leg portion 22. In this case, too, it is desirable that the gap hole 24 be formed at the end in the longitudinal direction of the outer leg portion 22. Furthermore, the gap hole 24 may also be formed in the connecting portion 23.

[0089] In the above embodiment, a single gap hole 24 is formed in the core 20, but multiple gap holes 24 may be formed in the core 20. For example, gap holes 24 may be formed at both longitudinal ends of the center leg 21. Furthermore, one gap hole 24 may be formed in each of the center leg 21 and the outer leg 22. Furthermore, at least one of the multiple magnetic gaps formed in the core 20 may be a V-shaped gap hole 24, and the remaining magnetic gaps may be of another type, such as a normal gap (Comparative Example 1) or a linear gap hole (Comparative Example 2). Furthermore, the gap hole 24 may be formed in a U-shape. Furthermore, in the above embodiment, the entire gap hole 24 is formed in the center leg 21, but it is sufficient that at least a portion of the gap hole 24 is formed at the boundary between the center leg 21 and the connecting portion 23.

[0090] In the above embodiment, the injection port 62 of the jig 60 is inserted into the extension portion 242 to fill the gap hole 24 with magnetic resin 30, but in another embodiment, the injection port 62 may be installed above the extension portion 242, and the magnetic resin 30 may be poured into the gap hole 24 from the injection port 62 installed above the extension portion 242 to fill it.

[0091] In the above embodiment, the gap hole 24 is filled with magnetic resin 30, but in another embodiment, the gap hole 24 may be filled with a resin that does not contain soft magnetic powder. With a resin that does not contain soft magnetic powder, it is not possible to adjust the effective permeability or DC superposition characteristics or reduce leakage magnetic flux from the gap hole 24, but it improves the rigidity of the core 20 around the gap hole 24, thereby minimizing vibration of the core 20 caused by the electromagnetic attractive force generated within the gap hole 24 and noise associated with this vibration. Also, the gap hole 24 does not need to be filled with anything.

[0092] Although the core 20 in the above embodiment has a pair of outer legs 22 (outer leg 22A and outer leg 22B joined together), the core 20 may have a single outer leg 22 or three or more outer legs 22.

[0093] The above embodiment is an example of applying the present invention to an EI-type laminated magnetic core, but the present invention can also be applied to magnetic cores of other shapes (e.g., EER-type, EE-type, PQ-type, etc.) or other materials (e.g., powder magnetic cores, ferrite magnetic cores, amorphous metal magnetic cores, metal composite magnetic cores formed from resin containing magnetic particles, etc.).

[0094] In the above embodiment, the present invention is applied to a reactor, but the present invention is not limited to this configuration and can be applied to various inductors such as transformers and choke coils. [Explanation of symbols]

[0095] 1 Coil device 10 coils 20 cores 20A laminated core (E core) 20Ad Bridge 20B laminated core (I core) 21A, 21B Middle leg 22A, 22B Outer legs 23A, 23B Connection part (yoke part) 24 Gap hole 30 Magnetic resin 50 molds 60 Jig G gap length

Claims

1. The yoke and a leg portion having one end connected to one surface of the yoke portion; Equipped with a V-shaped gap hole is formed across the boundary between the yoke portion and the leg portion; core.

2. Both ends of the V-shaped gap hole are located in the yoke portion, The apex of the V-shaped gap hole is located on the leg portion. The magnetic core according to claim 1 .

3. The yoke and a leg portion having one end connected to one surface of the yoke portion; Equipped with A V-shaped gap hole is formed at one end of the leg portion. core.

4. Both ends of the V-shaped gap hole are located at the boundary between the yoke portion and the leg portion. The magnetic core according to claim 3 .

5. The apex of the V-shaped gap hole is located at the boundary between the yoke portion and the leg portion. The magnetic core according to claim 3 .

6. The gap hole is symmetrical about a central plane that is a plane including a centerline extending in the longitudinal direction of the leg. The magnetic core according to any one of claims 1 to 5.

7. a bridge width, which is the distance from a side surface of the leg portion parallel to the center plane to the gap hole, is within a range of 0.5 mm to 2.5 mm; The magnetic core according to claim 6.

8. The V-shaped angle of the gap hole is within a range of 30° to 120°. A magnetic core according to any one of claims 1 to 7.

9. It is a laminated magnetic core consisting of multiple stacked core plates, Each of the core plates has an element gap hole formed therein; The element gap holes of the stacked core plates are connected to each other to form the gap holes. A magnetic core according to any one of claims 1 to 8.

10. A coil and A magnetic core according to any one of claims 1 to 9; Equipped with The legs are inserted into the coil. Coil device.

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