Magnetic core, electromagnetic device, and method for manufacturing magnetic core

Abstract

The present invention provides a magnetic core having a higher magnetic flux density than conventional magnetic cores. The magnetic core (120) includes partial regions (121, 122, 123a, 123b) formed integrally with each other. The partial regions (121, 122, 123a, 123b) are connected to each other at connecting surfaces that include a curved part of the surface of the magnetic core (120). The magnetic core (120) is formed such that one of the partial regions (121, 122, 123a, 123b) has an axis of easy magnetization in one predetermined direction.

Description

Magnetic Core, Electromagnetic Device, and Method for Manufacturing Magnetic Core

[0001] The present disclosure relates to a magnetic core, an electromagnetic device, and a method for manufacturing a magnetic core.

[0002] Various magnetic cores are used in electromagnetic devices such as motors, transformers, and inductors.

[0003] For example, Patent Document 1 discloses a core for a rotating electrical machine and a method for manufacturing the core for a rotating electrical machine. A magnet-embedded type motor including a rotor core made of a permanent magnet and a stator core made of an amorphous soft magnetic material is disclosed.

[0004] Japanese Patent No. 7211313

[0005] In order to miniaturize an electromagnetic device and, in the case of a motor, to improve its torque, it is required to improve the magnetic flux density of the magnetic core.

[0006] An object of the present disclosure is to provide a magnetic core having a higher magnetic flux density than conventional ones and a method for manufacturing the same. Another object of the present disclosure is to provide an electromagnetic device including such a magnetic core.

[0007] A magnetic core according to one aspect of the present disclosure is a magnetic core including a plurality of partial regions integrally formed with each other, the plurality of partial regions being connected to each other at a connecting surface including a bent portion on the surface of the magnetic core, and one of the plurality of partial regions being formed so as to have an easy axis of magnetization in a predetermined one direction.

[0008] According to one aspect of the present disclosure, a magnetic core having a higher magnetic flux density than conventional ones can be provided .

[0009] Figure 2 is a vertical cross-sectional view showing an example of the configuration of the motor 101 according to the first embodiment. Figure 3 is a horizontal cross-sectional view showing an example of the configuration of the motor 101 according to the first embodiment. Figure 4 is a perspective view showing one of the magnetic cores 120 of the outer core 108 in Figure 2. Figure 4 is a horizontal cross-sectional view showing one of the magnetic cores 120 of the outer core 108 in Figure 2. Figure 5 is a diagram showing the crystal structure of iron. Figure 6 is a diagram showing the easy magnetization axis and hard magnetization axis of iron. Figure 7 is a graph showing the magnetization curve of iron. Figure 8 is a graph showing the magnetization curves of grain-oriented electrical steel sheets and non-grain-oriented electrical steel sheets. Figure 9 is a schematic diagram showing an additive manufacturing apparatus 200 for forming the magnetic core 120 in Figure 4. Figure 9 is a graph showing the magnetization curves in the Xb, Yb, and Zb axes of the magnetic core formed by the additive manufacturing apparatus 200 in Figure 9. Figure 9 is a diagram showing the first step in forming the magnetic core 120 in Figure 4. Figure 1 is a diagram showing the second step in forming the magnetic core 120 in Figure 4. Figure 9 is a diagram showing the third step in forming the magnetic core 120 in Figure 4. Figure 1 is a diagram showing the fourth step in forming the magnetic core 120 in Figure 4. This figure shows the crystal structure in the Xb-Yb plane of the magnetic core 120 formed by the additive manufacturing apparatus 200 of Figure 9. This figure shows the crystal structure in the Xb-Zb plane of the magnetic core 120 formed by the additive manufacturing apparatus 200 of Figure 9. This figure shows the crystal structure in the Yb-Zb plane of the magnetic core 120 formed by the additive manufacturing apparatus 200 of Figure 9. This figure shows the magnetic flux generated in the stator 103 of Figure 2. This is a schematic diagram showing an additive manufacturing apparatus 300 for forming a magnetic core 120A according to a modified example of the first embodiment. This is a cross-sectional view showing a transformer 400 according to the second embodiment. This figure shows the magnetic core 401 of Figure 20. This figure shows the first step in forming the magnetic core 401 of Figure 20. This figure shows the second step in forming the magnetic core 401 of Figure 20. This figure shows the third step in forming the magnetic core 401 of Figure 20. This figure shows the fourth step in forming the magnetic core 401 of Figure 20. This is a cross-sectional view showing an inductor 430 according to the third embodiment.

[0010] The embodiments of this disclosure will be described in detail below with reference to the drawings. However, the configurations described below are merely examples of this disclosure, and this disclosure is not limited to the embodiments described below. Various modifications are possible in other embodiments as long as they do not depart from the technical idea related to this disclosure, depending on the design, etc.

[0011] [First Embodiment] [Motor Configuration] Figure 1 is a longitudinal cross-sectional view showing an example of the configuration of a motor 101 according to the first embodiment. Figure 2 is a transverse cross-sectional view showing an example of the configuration of a motor 101 according to the first embodiment. In this embodiment, a motor having an inner rotor type configuration with a rotor inside the stator, a magnet on the rotor, and windings on the stator will be described.

[0012] The motor 101 comprises a rotor 102, a stator 103, a pair of bearings 107, and a housing 110. The stator 103 and bearings 107 are fixed to the housing 110. The rotor 102 is rotatably supported inside the stator 103 by the pair of bearings 107.

[0013] In Figure 2, the housing 110 is omitted for the sake of simplicity in the illustration.

[0014] In this specification, the direction in which the rotation axis 106 extends (the Z direction in Figure 1, etc.) is referred to as the direction of the rotation axis 106 or the axial direction. In a plane perpendicular to this axial direction (the XY plane in Figure 2, etc.), the direction extending from the center of the rotation axis 106 is referred to as the radial direction, and the direction revolving around the center is referred to as the circumferential direction.

[0015] The rotor 102 comprises an inner core 104, a plurality of magnets 105, and a rotating shaft 106. The inner core 104 is a magnetic core having a substantially cylindrical shape. The rotating shaft 106 passes through the inner core 104, and the inner core 104 is mechanically connected to the rotating shaft 106. The rotating shaft 106 is supported by a pair of bearings 107, and the rotor 102 rotates around the rotating shaft 106. The plurality of magnets 105 are permanent magnets provided at equal intervals along the outer circumference of the inner core 104. In the example in Figure 2, 10 magnets 105 are provided. For example, each magnet 105 has a rectangular parallelepiped shape, and the inner core 104 has a plurality of substantially rectangular holes formed at equal intervals along its outer circumference, into which each magnet 105 is inserted. Each magnet 105 becomes a magnetic pole of the rotor 102.

[0016] The inner core 104 mainly contains iron. The inner core 104 may also contain, for example, 97% or more iron and 3% or less silicon as its components.

[0017] The inner core 104 may be formed by laminating multiple non-oriented electrical steel sheets in the direction of the rotation axis 106. Alternatively, the inner core 104 may be formed using additive manufacturing from a material that is easy to form, such as compacted magnetic core material or soft magnetic metal powder.

[0018] The rotor 102 has a magnet-embedded configuration in which the magnet 105 is embedded inside the inner core 104 so as not to be exposed on the surface of the inner core 104.

[0019] The stator 103 comprises an outer core 108 and a plurality of windings 109. The outer core 108 comprises a plurality of magnetic cores 120 arranged circumferentially and connected to one another. In the example shown in Figure 2, twelve magnetic cores 120 are provided.

[0020] Figure 3 is a perspective view showing one of the magnetic cores 120 of the outer core 108 in Figure 2. Figure 4 is a cross-sectional view showing one of the magnetic cores 120 of the outer core 108 in Figure 2. In Figure 4, "O" indicates the center of the rotation axis 106.

[0021] As shown in Figure 4, the magnetic core 120 includes integrally formed partial regions 121, 122, 123a, and 123b. Partial region 121 is formed to extend along the outer circumference of the stator 103. Partial region 122 protrudes from partial region 121 toward the center of the stator 103. Partial regions 123a and 123b protrude from the tip of partial region 122 along the inner circumference of the stator 103. Partial regions 121, 122, 123a, and 123b are connected to each other at connecting surfaces C1 to C3, which include the bent portions B1 to B4 on the surface of the magnetic core 120. The surface of the magnetic core 120 is bent at the bent portions B1 and B2, and partial regions 121 and 122 are connected to each other at connecting surface C1, which includes the bent portions B1 and B2. The surface of the magnetic core 120 is bent at the bent portion B3, and the partial regions 122 and 123a are connected to each other at the connecting surface C2 which includes the bent portion B3. The surface of the magnetic core 120 is bent at the bent portion B4, and the partial regions 122 and 123b are connected to each other at the connecting surface C3 which includes the bent portion B4. The partial regions 121, 122, 123a, and 123b can be visually distinguished from each other by referring to the bent portions B1 to B4.

[0022] The magnetic core 120 is formed such that at least one of a plurality of subregions has an easy magnetization axis in a predetermined direction. Alternatively, the magnetic core 120 may be formed such that a first subregion of the plurality of subregions has a first easy magnetization axis in a first direction, and a second subregion of the plurality of subregions has a second easy magnetization axis in a second direction different from the first direction. Alternatively, the magnetic core 120 may be formed such that the plurality of subregions have easy magnetization axes in different directions from each other. In the example in Figure 4, subregions 121, 122, 123a, and 123b are formed to have easy magnetization axes in the direction of the thick arrows. Subregion 121 is formed to have an easy magnetization axis in a direction perpendicular to the radial direction of the stator 103 in a plane perpendicular to the rotation axis 106 of the rotor 102 (i.e., the XY plane in Figure 4). In other words, partial region 121 is formed to have an easy magnetization axis substantially along the outer circumference of the stator 103. Partial region 122 is formed to have an easy magnetization axis in the radial direction of the stator 103. Partial regions 123a and 123b are formed to have an easy magnetization axis along the inner circumference of the stator 103.

[0023] The magnetic core 120 is formed using an additive manufacturing method from a material such as easily moldable compacted magnetic core material or soft magnetic metal powder (details described later). At least one of the multiple subregions has an easy magnetization axis in the direction in which layers of magnetic material are stacked using the additive manufacturing method. At least one of the multiple subregions has a longitudinal direction of crystal grains in one predetermined direction, thereby having an easy magnetization axis in one predetermined direction. Each of the subregions 121, 122, 123a, and 123b may have an easy magnetization axis in the direction in which layers of magnetic material are stacked using the additive manufacturing method. Each of the subregions 121, 122, 123a, and 123b may have a longitudinal direction of crystal grains in one predetermined direction, thereby having an easy magnetization axis in one predetermined direction. Each of the subregions 121, 122, 123a, and 123b may be formed to have an easy magnetization axis in the direction in which the magnetic flux generated by the winding 109 flows.

[0024] The magnetic core 120 is formed from a predetermined magnetic material. The magnetic core 120 may be formed from a soft magnetic material containing, for example, (a) iron, (b) a combination of iron and silicon, or (c) a combination of iron and cobalt. The magnetic core 120 may contain 96.5 to 97% iron and 3 to 3.5% silicon as components. The magnetic core 120 may be permendur containing 49% iron, 49% cobalt, and 2% vanadium as components.

[0025] Referring again to Figure 2, by connecting the multiple magnetic cores 120 arranged in the circumferential direction to each other, the partial regions 121 of these magnetic cores 120 form an annular yoke, and the partial regions 122 of each magnetic core 120 protrude inward from the yoke and extend radially. Each partial region 122 is arranged at equal intervals along the inner circumference of the yoke so that its tip faces the inner core 104.

[0026] By providing partial regions 123a and 123b that protrude along the inner circumference of the stator 103 at the tip of partial region 122, it becomes easier to form a desired magnetic path between the rotor 102 and the stator 103.

[0027] The inner core 104 and the outer core 108 are formed to be rotatable relative to each other around a common axis of rotation 106. The inner core 104 is positioned inside the outer core 108 such that the tips of each projection 132 of the outer core 108 face the outer circumferential surface of the rotor 102 through a gap.

[0028] The rotor 102 and stator 103 configured in this way are arranged inside the housing 110 as shown in Figure 1 to form the motor 101. The rotating shaft 106 extends axially from the inner core 104, and one end of the rotating shaft 106 protrudes outside the housing 110 as an output shaft for rotationally driving a load.

[0029] The motor 101 may be a brushless motor driven by a three-phase AC current including U-phase, V-phase, and W-phase, which are 120 degrees out of phase with respect to each other. A current of either the U-phase, V-phase, or W-phase is applied to the multiple windings 109.

[0030] [Easy magnetization axis of magnetic core] Figure 5 shows the crystal structure of iron. Figure 6 shows the easy magnetization axis and hard magnetization axis of iron. Iron has a body-centered cubic lattice structure. Iron has an easy magnetization axis in the

[100] direction and a hard magnetization axis in the

[111] direction.

[0031] Figure 7 is a graph showing the magnetization curve of iron. As shown in Figure 7, iron is most easily magnetized when a magnetic field is applied in the

[100] direction.

[0032] Figure 8 is a graph showing the magnetization curves of grain-oriented electrical steel sheets and non-oriented electrical steel sheets. "RD" indicates that a magnetic field is applied in the rolling direction of the grain-oriented electrical steel sheet, and "TD" indicates that a magnetic field is applied in the transverse direction of the grain-oriented electrical steel sheet. As shown in Figure 8, grain-oriented electrical steel sheets are most easily magnetized when a magnetic field is applied in their rolling direction (RD). However, the magnetic flux in the magnetic core of electromagnetic devices such as motors, transformers, and inductors does not always flow along the rolling direction throughout the entire structure. For this reason, magnetic cores using grain-oriented electrical steel sheets may have partially low magnetic flux density. Taking this into consideration, non-oriented electrical steel sheets are often used for magnetic cores in electromagnetic devices. In this case, the magnetic flux density is generally lower than when grain-oriented electrical steel sheets are used.

[0033] Therefore, there is a need to provide a magnetic core that is easier to magnetize and has a higher magnetic flux density than when using either non-oriented electrical steel sheets or grain-oriented electrical steel sheets. The magnetic core 120 according to the embodiment can be formed as described below to be easier to magnetize and have a higher magnetic flux density than when using either non-oriented electrical steel sheets or grain-oriented electrical steel sheets.

[0034] [Method for Manufacturing Magnetic Cores] Figure 9 is a schematic diagram showing an additive manufacturing apparatus 200 for forming the magnetic core 120 shown in Figure 4. The additive manufacturing apparatus 200 creates objects using directed energy deposition (DED). The additive manufacturing apparatus 200 comprises a housing 201, a nozzle 202, a laser light source 203, and a drive device 204. The inside of the housing 201 is filled with gas 205. The nozzle 202 is supplied with metal powder of magnetic material, such as easily moldable compacted magnetic core material or soft magnetic metal powder. The laser light source 203 irradiates the metal powder supplied from the nozzle 202 with laser light 206, melting and depositing the metal powder. The drive device 204 moves the nozzle 202 and the laser light source 203 in three dimensions. The additive manufacturing apparatus 200 repeatedly forms linear deposits 220 having a longitudinal direction along the Yb axis, thereby forming layers of deposits along the Xb-Yb plane, and stacks the layers of deposits in the Zb axis direction to form a magnetic core 120. In this specification, the Zb axis direction of the additive manufacturing apparatus 200 is referred to as the "stacking direction".

[0035] Figure 10 is a graph showing the magnetization curves in the Xb, Yb, and Zb axes of a magnetic core formed by the additive manufacturing apparatus 200 shown in Figure 9. Figure 10 shows the magnetic flux density when a magnetic field is applied in the Xb, Yb, and Zb axes for a rectangular magnetic core having dimensions of 38 mm in the Xb axis direction, 60 mm in the Yb axis direction, and 49.6 mm in the Zb axis direction. When a magnetic field of 5000 A / m was applied in the Zb axis direction, the magnetic flux density became 1.68 T. Also, when magnetic fields of 5000 A / m were applied in the Xb and Yb axis directions, the magnetic flux density became 1.48 T, respectively. From this, it can be seen that the magnetic core formed by the additive manufacturing apparatus 200 shown in Figure 9 has an easy magnetization axis in the Zb axis direction, i.e., in the stacking direction.

[0036] Figures 11 to 14 show the first to fourth steps for forming the magnetic core 120 shown in Figure 4. Figures 11 to 14 show the process of forming the magnetic core 120 using the additive manufacturing apparatus 200 shown in Figure 9. For the sake of simplicity, Figures 11 to 14 show only the laser light source 203 (and laser beam 206) of the additive manufacturing apparatus 200 shown in Figure 9.

[0037] The additive manufacturing apparatus 200 forms the magnetic core 120 using additive manufacturing so that each of the partial regions 121, 122, 123a, and 123b of the magnetic core 120 has an easy magnetization axis in a predetermined direction. Each of the partial regions 121, 122, 123a, and 123b has an easy magnetization axis in the direction in which layers of magnetic material are stacked using additive manufacturing.

[0038] Figure 11 shows the process of forming the partial region 121 in Figure 4. The additive manufacturing apparatus 200 stacks layers 221 of deposits in the Zb axis direction, thereby ultimately forming the partial region 121 in Figure 4. The partial region 121 has an easy magnetization axis in the stacking direction. Therefore, the partial region 121 is formed such that it has an easy magnetization axis in a direction perpendicular to the radial direction of the stator 103 in a plane perpendicular to the rotation axis 106 of the rotor 102.

[0039] Figure 12 shows the process of forming the partial region 122 of Figure 4. The additive manufacturing apparatus 200 stacks layers 222 of deposits in the Zb axis direction, thereby ultimately forming the partial region 122 of Figure 4. The partial region 122 has an easy magnetization axis in the stacking direction. Therefore, the partial region 122 is formed to have an easy magnetization axis in the radial direction of the stator 103.

[0040] Figure 13 shows the process of forming the partial region 123a in Figure 4. The additive manufacturing apparatus 200 stacks layers 223 of deposits in the Zb axis direction, thereby ultimately forming the partial region 123a in Figure 4. The partial region 123a has an easy magnetization axis in the stacking direction. Therefore, the partial region 123a is formed to have an easy magnetization axis along the inner circumference of the stator 103.

[0041] Figure 14 shows the process of forming the partial region 123b in Figure 4. The additive manufacturing apparatus 200 stacks layers 224 of deposits in the Zb axis direction, thereby ultimately forming the partial region 123b in Figure 4. The partial region 123b has an easy magnetization axis in the stacking direction. Therefore, the partial region 123b is formed to have an easy magnetization axis along the inner circumference of the stator 103.

[0042] [Effect of the First Embodiment] FIG. 15 is a diagram showing the crystal structure in the Xb-Yb plane of the magnetic core 120 formed by the additive manufacturing apparatus 200 of FIG. 9. FIG. 16 is a diagram showing the crystal structure in the Xb-Zb plane of the magnetic core 120 formed by the additive manufacturing apparatus 200 of FIG. 9. FIG. 17 is a diagram showing the crystal structure in the Yb-Zb plane of the magnetic core 120 formed by the additive manufacturing apparatus 200 of FIG. 9. In FIGS. 15 to 17, the thin lines indicate the linear deposits 220 formed by the additive manufacturing apparatus 200 of FIG. 9, and the thick lines indicate the crystal grains 230 generated by laminating the layers 221 to 224 of the deposits. Each layer of the deposits deposited by the additive manufacturing apparatus 200 solidifies in the order of deposition. The structure of the upper deposit grows under the influence of the structure of the lower deposit (epitaxial growth). Therefore, as shown in FIGS. 15 to 17, the crystal grains 230 have a longitudinal direction in the Zb-axis direction, that is, the lamination direction, and the longitudinal direction of the crystal grains 230 coincides with the direction of the easy magnetization axis.

[0043] FIG. 18 is a diagram showing the magnetic flux generated in the stator 103 of FIG. 2. Referring to FIGS. 4 and 18, when a magnetic field is applied to a certain magnetic core 120 by the winding 109, in the partial region 121, magnetic flux flows in a direction perpendicular to the radial direction of the stator 103, and in the partial region 122, magnetic flux flows in the radial direction of the stator 103. In the partial regions 123a and 123b, magnetic flux flows along the inner circumference of the stator 103; therefore, each of the partial regions 121, 122, 123a, and l2 and 3b has an easy magnetization axis in the direction in which the magnetic flux generated by the winding 109 flows.

[0044] Since at least one of the plurality of partial regions of the magnetic core 120 has an easy magnetization axis in a predetermined one direction, it is easier to magnetize than in the case of an isotropic electromagnetic steel sheet, and a higher magnetic flux density can be brought about. Further, since the magnetic core 120 has an easy magnetization axis in the direction in which the magnetic flux generated by the winding 109 flows, for example, as shown in FIG. 4, it is easier to magnetize than in either the case of an isotropic electromagnetic steel sheet or an anisotropic electromagnetic steel sheet, and a higher magnetic flux density can be brought about ;

[0045] By improving the magnetic flux density of the magnetic core 120, the motor 101 can be miniaturized or the torque of the motor 101 can be improved.

[0046] [Modification of the First Embodiment] FIG. 19 is a schematic view showing a laminated manufacturing apparatus 300 for forming a magnetic core 120A according to a modification of the first embodiment. The laminated manufacturing apparatus 300 creates an object using the powder bed fusion method (Powder Bed Fusion: PBF). The laminated manufacturing apparatus 300 includes a housing 301, a laser light source 302, and a drive device 303. The housing 301 is filled with a metal powder 304 of a magnetic material from the bottom surface to a predetermined height. The laser light source 302 irradiates the metal powder 304 with a laser beam 305 to melt and deposit the metal powder 304 once. The drive device 303 moves the laser light source 302 three-dimensionally. The laminated manufacturing apparatus 300 forms a layer 311 of deposits in the Xc - Yc plane. When one layer 311 is formed, the metal powder 304 is filled up to a predetermined height from the layer 311, and then the laminated manufacturing apparatus 300 forms the next layer 311 of deposits in the Xc - Yc plane. The layers 311 of deposits are laminated in the Zc-axis direction to form the magnetic core 120A. In this specification, the Zc-axis direction of the laminated manufacturing apparatus 300 is referred to as the "lamination direction".

[0047] In the example of FIG. It forms the magnetic core 容易軸を有するように、磁性体コア120Aを形成する。また、積層造形装置300は、図11~図14に示す場合と同様に、堆積物の層をZc方向に積層して部分領域121,1例えば、図4の各太矢印の向きに磁化容易軸を有するように磁性体コア120を形成してもよい。

[0048] [Second Embodiment] FIG. 20 is a cross-sectional view showing a transformer 400 according to the second embodiment. The transformer 400 includes magnetic cores 401a and 401b, a primary winding 402, and a secondary winding 403. The magnetic cores 401a and 401b each have an E shape and are connected to each other to form a closed magnetic circuit. The primary winding 40例えば、2 and the secondary winding 403 are wound around the magnetic cores easy軸を有するように、磁性体コア401a,401bに巻回される。

[0049] Hereafter, the magnetic cores 401a and 401b will be collectively referred to as "magnetic core 401".

[0050] Figure 21 shows the magnetic core 401 of Figure 20. The magnetic core 401 includes partial regions 411 to 414 that are integrally formed with each other. Partial region 411 is formed to extend over a predetermined length. Partial regions 412 to 414 are formed to extend perpendicularly to partial region 411 and in the same direction. Partial regions 412 to 414 are connected to each other at connecting surfaces C11 to C13 that include bent portions B11 to B14 on the surface of the magnetic core 401. The surface of the magnetic core 401 is bent at bent portion B11, and partial regions 411 and 412 are connected to each other at connecting surface C11 that includes bent portion B11. The surface of the magnetic core 401 is bent at bent portions B12 and B13, and partial regions 411 and 413 are connected to each other at connecting surface C12 that includes bent portions B12 and B13. The surface of the magnetic core 401 is bent at the bent portion B14, and the partial regions 411 and 414 are connected to each other at the connecting surface C13 which includes the bent portion B14. The partial regions 411 to 414 can be visually distinguished from each other by referring to the bent portions B11 to B14.

[0051] The magnetic core 401 is formed such that at least one of the multiple subregions has an easy magnetization axis in a predetermined direction. Alternatively, the magnetic core 401 may be formed such that a first subregion of the multiple subregions has a first easy magnetization axis in a first direction, and a second subregion of the multiple subregions has a second easy magnetization axis in a second direction different from the first direction. Alternatively, the magnetic core 401 may be formed such that the multiple subregions have easy magnetization axes in different directions from each other. In the example in Figure 21, subregions 411 to 414 are formed so that they each have an easy magnetization axis in the direction of the thick arrows. Subregion 411 is formed so that it has an easy magnetization axis in its longitudinal direction. Subregions 412 to 414 are formed so that they have easy magnetization axes perpendicular to and in the same direction as subregion 411.

[0052] [Method for Manufacturing a Magnetic Core] Figures 22 to 25 show the first to fourth steps for forming the magnetic core 401 shown in Figure 20. Figures 22 to 25 show the steps for forming the magnetic core 401 using the additive manufacturing apparatus 200 shown in Figure 9. For the sake of simplicity, Figures 22 to 25 show only the laser light source 203 (and laser beam 206) of the additive manufacturing apparatus 200 shown in Figure 9.

[0053] The additive manufacturing apparatus 200 forms the magnetic core 401 using an additive manufacturing method such that each of the partial regions 411 to 414 of the magnetic core 401 has an easy magnetization axis in a predetermined direction. Each of the partial regions 411 to 414 has an easy magnetization axis in the direction in which layers of magnetic material are stacked using the additive manufacturing method.

[0054] Figure 22 shows the process of forming the partial region 411 of Figure 21. The additive manufacturing apparatus 200 stacks layers 421 of deposits in the Zb axis direction, thereby ultimately forming the partial region 411 of Figure 21. The partial region 411 has an easy magnetization axis in the stacking direction. Therefore, the partial region 411 is formed to have an easy magnetization axis in its longitudinal direction.

[0055] Figure 23 shows the process of forming the partial region 412 of Figure 21. The additive manufacturing apparatus 200 stacks layers 422 of deposits in the Zb axis direction, thereby ultimately forming the partial region 412 of Figure 21. The partial region 412 has an easy magnetization axis in the stacking direction. Therefore, the partial region 412 is formed to have an easy magnetization axis perpendicular to the partial region 411.

[0056] Figure 24 shows the process of forming the partial region 413 of Figure 21. The additive manufacturing apparatus 200 stacks layers 423 of deposits in the Zb axis direction, thereby ultimately forming the partial region 413 of Figure 21. The partial region 413 has an easy magnetization axis in the stacking direction. Therefore, the partial region 413 is formed to have an easy magnetization axis perpendicular to the partial region 411 and in the same direction as the partial region 412.

[0057] Figure 25 shows the process of forming the partial region 414 of Figure 21. The additive manufacturing apparatus 200 stacks layers 424 of deposits in the Zb axis direction, thereby ultimately forming the partial region 414 of Figure 21. The partial region 414 has an easy magnetization axis in the stacking direction. Therefore, the partial region 414 is formed to have an easy magnetization axis perpendicular to the partial region 411 and in the same direction as the partial regions 412 and 413.

[0058] The magnetic core 401 may be formed using the additive manufacturing apparatus 300 shown in Figure 19.

[0059] Since the magnetic core 401 has an easy magnetization axis in at least one of its multiple sub-regions in a predetermined direction, it is easier to magnetize than non-oriented electrical steel sheets and can produce a higher magnetic flux density. Furthermore, by having an easy magnetization axis in the direction in which the magnetic flux generated by the primary winding 402 and secondary winding 403 flows, as shown in Figure 21, for example, the magnetic core 401 is easier to magnetize than both non-oriented and oriented electrical steel sheets and can produce a higher magnetic flux density.

[0060] By improving the magnetic flux density of the magnetic core 401, the transformer 400 can be miniaturized.

[0061] In conventional transformers, a grain-oriented electrical steel sheet bent into a loop shape is sometimes used as the magnetic core. In this case, the shape of the magnetic core is limited to a loop shape, and at least one break point occurs in the loop. On the other hand, according to this embodiment, by using additive manufacturing, a magnetic core 401 with a complex shape can be provided without creating any break points.

[0062] [Third Embodiment] Figure 26 is a cross-sectional view showing an inductor 430 according to a third embodiment. The inductor 430 has magnetic cores 401a, 401b and a winding 431. The magnetic cores 401a, 401b in Figure 26 are the same as the magnetic cores 401a, 401b in Figure 20. The winding 431 is wound around the magnetic cores 401a, 401b. By improving the magnetic flux density of the magnetic core 401, the inductor 430 can be miniaturized.

[0063] [Other Embodiments] The disclosed embodiments and their variations may be combined as appropriate.

[0064] In the embodiment described, a motor having an inner rotor configuration with a rotor inside the stator, a magnet on the rotor, and windings on the stator was described. However, the described principle is also applicable to a motor having an outer rotor configuration with a rotor outside the stator, and also to a motor having windings on the rotor and a magnet on the stator.

[0065] The described embodiment is applicable not only to motors but also to other rotating electric machines such as generators.

[0066] The magnetic core of the transformer may have a different configuration than that shown in Figure 20. The magnetic core of the inductor may have a different configuration than that shown in Figure 26.

[0067] [Summary of Embodiments] The magnetic core and electromagnetic device, as well as the method for manufacturing the magnetic core, according to each embodiment of the present disclosure, are configured as follows.

[0068] A magnetic core according to a first aspect of the present disclosure is a magnetic core including a plurality of integrally formed subregions, wherein the plurality of subregions are connected to each other at a connecting surface including a bent portion of the surface of the magnetic core, and one of the plurality of subregions is formed to have an easy magnetization axis in a predetermined direction.

[0069] According to a magnetic core according to a second aspect of the present disclosure, in the magnetic core according to the first aspect, one of the plurality of partial regions has a longitudinal direction of crystal grains in one predetermined direction.

[0070] According to a third aspect of the present disclosure, in a magnetic core according to the first or second aspect, the magnetic core is the core of a motor, transformer, or inductor.

[0071] According to a fourth aspect of the present disclosure, in a magnetic core according to one of the first to third aspects, the magnetic core is a part of the core of the stator of an inner rotor type motor having a rotor inside the stator. The magnetic core includes a first partial region along the outer circumference of the stator, a second partial region projecting from the first partial region toward the center of the stator, and a third partial region projecting from the tip of the second partial region along the inner circumference of the stator. The first partial region is formed such that it has the easy magnetization axis in a plane perpendicular to the rotation axis of the rotor and perpendicular to the radial direction of the stator.

[0072] According to a fifth aspect of the present disclosure, in a magnetic core according to one of the first to fourth aspects, the magnetic core is a part of the core of the stator of an inner rotor type motor having a rotor inside the stator. The magnetic core includes a first partial region along the outer circumference of the stator, a second partial region projecting from the first partial region toward the center of the stator, and a third partial region projecting from the tip of the second partial region along the inner circumference of the stator. The second partial region is formed to have the easy magnetization axis in the radial direction of the stator.

[0073] According to a sixth aspect of the present disclosure, in a magnetic core according to one of the first to fifth aspects, the magnetic core is a part of the core of the stator of an inner rotor type motor having a rotor inside the stator. The magnetic core includes a first partial region along the outer circumference of the stator, a second partial region projecting from the first partial region toward the center of the stator, and a third partial region projecting from the tip of the second partial region along the inner circumference of the stator. The third partial region is formed to have the easy magnetization axis along the inner circumference of the stator.

[0074] According to the seventh aspect of the present disclosure, in the magnetic core according to one of the first to sixth aspects, the magnetic core is made of a soft magnetic material including (a) iron, (b) a combination of iron and silicon, or (c) a combination of iron and cobalt.

[0075] According to the eighth aspect of the present disclosure, in a magnetic core according to one of the first to seventh aspects, a first partial region of the plurality of partial regions is formed to have a first easy magnetization axis in a first direction, and a second partial region of the plurality of partial regions is formed to have a second easy magnetization axis in a second direction different from the first direction.

[0076] According to the ninth aspect of the present disclosure, the electromagnetic device comprises a magnetic core according to the first aspect and at least one winding wound around the magnetic core, wherein each of a plurality of subregions of the magnetic core is formed to have an easy magnetization axis in the direction in which the magnetic flux generated by the winding flows.

[0077] According to the electromagnetic device of the tenth aspect of this disclosure, in the electromagnetic device of the ninth aspect, the electromagnetic device is a motor, a transformer, or an inductor.

[0078] According to the eleventh aspect of the present disclosure, a method for manufacturing a magnetic core according to the first aspect, comprising forming the magnetic core using additive manufacturing such that one of a plurality of partial regions of the magnetic core has an easy magnetization axis in a predetermined direction.

[0079] According to a method for manufacturing a magnetic core according to a twelfth aspect of the present disclosure, in the method for manufacturing a magnetic core according to an eleventh aspect, one of the plurality of partial regions has the magnetization easy axis in the direction in which layers of magnetic material are stacked using the additive manufacturing method.

[0080] This disclosure is applicable to a variety of electromagnetic devices, such as, for example, industrial servo motors, drive motors for electric vehicles or plug-in hybrid vehicles, generators, transformers, and inductors.

[0081] 101 Motor 102 Rotor 103 Stator 104 Inner core 105 Magnet 106 Rotating shaft 107 Bearing 108 Outer core 109 Winding 110 Housing 120, 120A Magnetic core 121, 122, 123a, 123b Partial region 200 Additive manufacturing device 201 Housing 202 Nozzle 203 Laser light source 204 Drive unit 205 Gas 206 Laser beam 220 Linear deposits 221-224 Deposit layer 230 Crystal grain 300 Additive manufacturing device 301 Housing 302 Laser light source 303 Drive unit 304 Metal powder 305 Laser beam 311 Deposit layer 400 Transformer 401, 401a, 401b Magnetic core 402 Primary winding 403 Secondary winding 411-414 Subregion 421-424 Sediment layer 430 Inductor 431 Winding

Claims

1. A magnetic core comprising a plurality of integrally formed subregions, wherein the plurality of subregions are connected to each other at a connecting surface including a bent portion of the surface of the magnetic core, and one of the plurality of subregions is formed to have an easy magnetization axis in a predetermined direction.

2. The magnetic core according to claim 1, wherein one of the plurality of subregions has the longitudinal direction of the crystal grains in the predetermined direction.

3. The magnetic core according to claim 1, wherein the magnetic core is the core of a motor, transformer, or inductor.

4. The magnetic core is a part of the core of the stator of an inner rotor type motor having a rotor inside the stator, and the magnetic core includes a first partial region along the outer circumference of the stator, a second partial region projecting from the first partial region toward the center of the stator, and a third partial region projecting from the tip of the second partial region along the inner circumference of the stator, wherein the first partial region is formed to have the easy magnetization axis in a plane perpendicular to the rotation axis of the rotor and perpendicular to the radial direction of the stator, the magnetic core according to claim 1.

5. The magnetic core is a part of the core of a stator of an inner rotor type motor having a rotor inside the stator, and the magnetic core includes a first partial region along the outer circumference of the stator, a second partial region projecting from the first partial region toward the center of the stator, and a third partial region projecting from the tip of the second partial region along the inner circumference of the stator, wherein the second partial region is formed to have the easy magnetization axis in the radial direction of the stator, as described in claim 1.

6. The magnetic core is a part of the core of a stator of an inner rotor type motor having a rotor inside the stator, and the magnetic core includes a first partial region along the outer circumference of the stator, a second partial region protruding from the first partial region toward the center of the stator, and a third partial region protruding from the tip of the second partial region along the inner circumference of the stator, wherein the third partial region is formed to have the easy magnetization axis along the inner circumference of the stator, as described in claim 1.

7. The magnetic core according to claim 1, wherein the magnetic core is made of a soft magnetic material comprising (a) iron, (b) a combination of iron and silicon, or (c) a combination of iron and cobalt.

8. The magnetic core according to claim 1, wherein a first subregion of the plurality of subregions has a first easy magnetization axis in a first direction, and a second subregion of the plurality of subregions has a second easy magnetization axis in a second direction different from the first direction.

9. An electromagnetic device comprising a magnetic core according to claim 1 and at least one winding wound around the magnetic core, wherein each of a plurality of partial regions of the magnetic core is formed to have an easy magnetization axis in the direction in which the magnetic flux generated by the winding flows.

10. The electromagnetic device according to claim 9, wherein the electromagnetic device is a motor, a transformer, or an inductor.

11. A method for manufacturing a magnetic core according to claim 1, comprising forming the magnetic core using additive manufacturing such that one of a plurality of partial regions of the magnetic core has an easy magnetization axis in a predetermined direction.

12. The manufacturing method according to claim 11, wherein one of the plurality of subregions has the easy magnetization axis in the direction in which layers of magnetic material are stacked using the additive manufacturing method.

Images