Electromechanical device

Abstract

This electromechanical device includes: a stator core (108); a rotor core (104) provided inside the stator core (108) so as to be rotatable around a rotating shaft (106); a plurality of windings (109) wound around the stator core (108); and a plurality of magnets (105) provided on the rotor core (104). The rotor core (104) includes: a plurality of outer members (112), each constituted by a first magnetic body provided outside the plurality of magnets (105) when viewed from the rotating shaft (106); an inner member (111) constituted by a magnetic body provided closer to the rotating shaft (106) than the plurality of outer members (112); and a plurality of bridge members (113) for mechanically connecting the plurality of outer members (112) to the inner member (111). Each of the plurality of bridge members (113) is at least partially made of a non-magnetic body.

Description

electromechanical devices

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to electromechanical devices.

[0002] Electromechanical devices such as motors or generators generally include magnets on one of a rotor and a stator, and windings on the other of the rotor and the stator, and convert electrical energy into mechanical energy or vice versa.

[0003] Patent Document 1 discloses a permanent magnet motor having a plurality of rectangular parallelepiped permanent magnets radially arranged on a rotor core.

[0004] JP 2017-046386 A

[0005] A portion of the magnetic flux generated by a magnet may travel along an undesired path, resulting in leakage flux. The leakage flux reduces the efficiency of converting electrical energy into mechanical energy, and vice versa. Therefore, in order to improve the efficiency of electromechanical devices, it is necessary to reduce the leakage flux.

[0006] An object of the present disclosure is to provide an electromechanical device that has improved efficiency compared to conventional devices by reducing leakage magnetic flux.

[0007] An electric machine device according to one aspect of the present disclosure comprises: a stator core; a rotor core arranged inside the stator core so as to be rotatable around a rotation axis; a plurality of windings wound around the stator core; and a plurality of magnets arranged on the rotor core, wherein the rotor core comprises a plurality of outer members each arranged outside the plurality of magnets when viewed from the rotation axis; an inner member arranged closer to the rotation axis than the plurality of outer members; and a plurality of bridge members each mechanically connecting the plurality of outer members to the inner member, wherein the plurality of outer members and the inner member are made of magnetic material, and each of the plurality of bridge members is made at least partially of non-magnetic material.

[0008] An electromechanical device according to one aspect of the present disclosure can improve efficiency compared to conventional devices by reducing leakage magnetic flux.

[0009] 2 is a longitudinal sectional view showing the configuration of a motor 101 according to a first embodiment. FIG. 3 is a transverse sectional view showing the configuration of a motor 101 according to the first embodiment. FIG. 4 is an enlarged view showing the configuration of a bridge member 113 of FIG. 2. FIG. 5 is a schematic view showing magnetic flux generated in a rotor 102A of a motor according to a comparative example. FIG. 6 is a schematic view showing magnetic flux generated in a rotor 102 of a motor 101 according to the first embodiment. FIG. 7 is a transverse sectional view showing the configuration of a rotor 102B of a motor according to a first modified example of the first embodiment. FIG. 8 is a transverse sectional view showing the configuration of a rotor 102C of a motor according to a second modified example of the first embodiment. FIG. 9 is a transverse sectional view showing the configuration of a rotor 102D of a motor according to a third modified example of the first embodiment. FIG. 10 is a transverse sectional view showing the configuration of a rotor 102E of a motor according to a fourth modified example of the first embodiment. FIG. 11 is a transverse sectional view showing the configuration of a rotor 102F of a motor according to a fifth modified example of the first embodiment. FIG. 12 is a transverse sectional view showing the configuration of a rotor 102G of a motor according to a sixth modified example of the first embodiment. FIG. 13 is a table showing simulation results regarding the torque of a motor including rotors 102, 102B to 102G according to the first embodiment. 20 is an enlarged view showing the configuration of a portion of a manufacturing apparatus for a motor 101 according to a first embodiment; FIG. 21 is a cross-sectional view showing the configuration of a rotor 102H of a motor according to a second embodiment; FIG. 22 is a longitudinal cross-sectional view showing the configuration of a motor 101I according to a third embodiment; FIG. 23 is a cross-sectional view showing the configuration of a motor 101I according to a third embodiment; FIG. 24 is an enlarged view showing the configuration of a bridge member 113I of FIG. 16; FIG. 25 is a table showing simulation results regarding the torque of a motor including a rotor 102I according to the third embodiment; FIG. 26 is a cross-sectional view showing the configuration of a rotor 102J of a motor according to a modified example of the third embodiment; FIG. 27 is a cross-sectional view showing the configuration of a motor 101K according to a fourth embodiment; FIG. 28 is an enlarged view showing the configurations of an outer member 112K and a bridge member 113I of FIG. 20; FIG. 29 is a schematic view showing magnetic flux generated in a rotor 102L of a motor according to a comparative example; FIG. 29 is a schematic view showing magnetic flux generated in a rotor 102K of a motor 101K according to a fourth embodiment.

[0010] Hereinafter, electromechanical devices according to embodiments of the present disclosure will be described in detail with reference to the drawings. However, the configurations described below are merely examples of the present disclosure, and the present disclosure is not limited to the following embodiments. Various modifications can be made depending on the design, etc., even if they are not the embodiments, as long as they do not deviate from the technical concept of the present disclosure.

[0011] [First embodiment] Fig. 1 is a longitudinal sectional view showing the configuration of a motor 101 according to a first embodiment. Fig. 2 is a transverse sectional view showing the configuration of the motor 101 according to the first embodiment.

[0012] The motor 101 includes a rotor 102, a stator 103, a pair of bearings 107, and a housing 110. The motor 101 has an inner rotor configuration in which the rotor 102 is provided inside the stator 103 so as to be rotatable around a rotation axis 106. The stator 103 and the 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 FIG. 2, the housing 110 is omitted for simplicity of illustration.

[0014] In this specification, the longitudinal direction of the rotation axis 106 (the Z direction in FIG. 1, etc.) is referred to as the direction of the rotation axis 106 or the axial direction, and in a plane perpendicular to this axial direction (the XY plane in FIG. 2, etc.), the direction spreading out from the center of the rotation axis 106 is referred to as the radial direction, and the direction going around the center is referred to as the circumferential direction.

[0015] The rotor 102 includes a rotor core 104, a plurality of magnets 105, and a rotating shaft 106. The rotor core 104 is a magnetic core having a substantially cylindrical shape. The rotating shaft 106 passes through the rotor core 104 and is mechanically coupled 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 periphery of the rotor core 104. In the example of FIG. 2 , ten magnets 105 are provided. For example, each magnet 105 has a rectangular parallelepiped shape, and the rotor core 104 has a plurality of substantially rectangular holes formed at equal intervals along its outer periphery, into which a magnet 105 is inserted. Each magnet 105 becomes a magnetic pole of the rotor 102.

[0016] The rotor core 104 includes an inner member 111, multiple outer members 112, and multiple bridge members 113. The multiple outer members 112 are each located outside the multiple magnets 105 when viewed from the rotation shaft 106. The inner member 111 is located closer to the rotation shaft 106 than the multiple outer members 112. The multiple bridge members 113 mechanically connect the multiple outer members 112 to the inner member 111. The inner member 111 and the outer member 112 are made of a magnetic material. The magnetic material contains iron as a main component, and may contain, for example, 97% or more iron and 3% or less silicon. Each of the multiple bridge members 113 is at least partially made of a non-magnetic material. The non-magnetic material may include, for example, a non-metal such as carbon fiber reinforced plastic (CFRP), ceramic, resin, or adhesive, or may include a metal such as aluminum, an aluminum alloy, non-magnetic stainless steel, or a titanium alloy.

[0017] The rotor 102 has a magnet-embedded configuration in which the magnets 105 are embedded inside the rotor core 104 so that they are not exposed on the surface of the rotor core 104 .

[0018] The stator 103 includes a stator core 108 and a plurality of windings 109. As shown in FIG. 2 , the stator core 108 includes an annular yoke 121 and a plurality of protrusions 122 (or teeth) that protrude inward from the yoke 121 and extend radially. The protrusions 122 are arranged at equal intervals along the inner circumference of the yoke 121 so that the tip of each protrusion 122 faces the rotor core 104. In the example shown in FIG. 2 , twelve protrusions 122 are provided. Each winding 109 is wound multiple times around the protrusions 122 of the stator core 108 via an insulating bobbin (not shown). Each winding 109 may be an insulating-coated round wire, a rectangular wire, or the like.

[0019] The stator core 108 contains iron as a main component, and may contain, for example, 97% or more iron and 3% or less silicon.

[0020] The rotor core 104 and the stator core 108 are formed to be rotatable relative to each other around a common rotation axis 106. The rotor core 104 is disposed inside the stator core 108 so that the tips of the protrusions 122 of the stator core 108 face the outer circumferential surface of the rotor 102 with a gap therebetween.

[0021] The rotor 102 and stator 103 configured in this manner are disposed inside a housing 110 as shown in Figure 1 to form a motor 101. A rotating shaft 106 extends axially from the rotor core 104, and one end of the rotating shaft 106 protrudes outside the housing 110 as an output shaft for driving a load to rotate.

[0022] The motor 101 may be a brushless motor driven by a three-phase AC including a U-phase, a V-phase, and a W-phase that are 120 degrees out of phase with each other. A current of any one of the U-phase, V-phase, and W-phase is applied to the multiple windings 109.

[0023] FIG. 3 is an enlarged view showing the configuration of the bridge member 113 in FIG. 2 . Each of the multiple magnets 105 is formed so that its longitudinal direction is perpendicular to the radial direction of the rotor core 104 in a cross section perpendicular to the rotation axis 106. Each of the multiple magnets 105 is arranged so that one of the north pole and south pole faces the rotation axis 106 and the other of the north pole and south pole faces the stator core 108. The multiple magnets 105 may be arranged so that adjacent magnets 105 along the circumferential direction of the rotor core 104 face in opposite directions, i.e., so that the north pole of one magnet faces the rotation axis 106 and the north pole of the other magnet faces the stator core 108. Each of the multiple bridge members 113 includes a first connecting member 131 and a second connecting member 132. The first connecting member 131 mechanically connects a pair of adjacent outer members 112 along the circumferential direction of the rotor core 104 to each other among the multiple outer members 112. The second connecting member 132 mechanically connects the first connecting member 131 to the inner member 111. Therefore, in the example of Fig. 3, the bridge member 113 has a T-shape. At least a portion of the first connecting member 131 is made of a non-magnetic material. Also, at least a portion of the second connecting member 132 may be made of a non-magnetic material. In the example of Fig. 3, the entire first connecting member 131 and the entire second connecting member 132 are made of a non-magnetic material.

[0024] 4 is a schematic diagram showing magnetic flux generated in rotor 102A of a motor according to a comparative example. Instead of bridge member 113, at least a portion of which is made of a non-magnetic material, rotor 102A includes bridge member 113A, the entirety of which is made of a magnetic material having the same relative permeability as that of inner member 111 and outer member 112. In this case, part of magnetic flux 151 generated by magnet 105 travels along bridge member 113A and becomes leakage magnetic flux 152.

[0025] Figure 5 is a schematic diagram showing magnetic flux generated in the rotor 102 of the motor 101 according to the first embodiment. Because the rotor 102 is provided with the bridge member 113 made of a non-magnetic material, the magnetic flux 153 traveling from the magnet 105 to the bridge member 113 is reduced compared to the leakage magnetic flux 152 in the case of Figure 4. Therefore, according to the motor 101 according to the first embodiment, the leakage magnetic flux is reduced compared to the case of Figure 4, thereby improving efficiency.

[0026] According to the first embodiment, it is possible to achieve a higher torque density than before, that is, a torque as large as possible for the same size, and in turn, it is possible to make the motor 101 smaller than before.

[0027] FIG. 6 is a cross-sectional view showing the configuration of a rotor 102B of a motor according to a first modified example of the first embodiment. The rotor 102B includes a bridge member 113B instead of the bridge member 113 of FIG. 3. The bridge member 113B includes a non-magnetic portion 113Ba made of a non-magnetic material and a magnetic portion 113Bb made of the same magnetic material as the inner member 111 and the outer member 112. The magnetic portion 113Bb is formed integrally with the inner member 111. The non-magnetic portion 113Ba is mechanically coupled to the adjacent outer member 112 and is further mechanically coupled to the magnetic portion 113Bb. As a result, the non-magnetic portion 113Ba and the magnetic portion 113Bb form a first coupling member that mechanically couples the outer members 112 to each other and a second coupling member that mechanically couples the first coupling member to the inner member 111.

[0028] FIG. 7 is a cross-sectional view showing the configuration of a rotor 102C of a motor according to a second modified example of the first embodiment. The rotor 102C includes a bridge member 113C instead of the bridge member 113 shown in FIG. 3. The bridge member 113C includes a non-magnetic portion 113Ca made of a non-magnetic material and a magnetic portion 113Cb made of the same magnetic material as the inner member 111 and the outer member 112. The non-magnetic portion 113Ca is mechanically coupled to the adjacent outer member 112. The magnetic portion 113Cb is integrally formed with the inner member 111 and is further mechanically coupled to the non-magnetic portion 113Ca. As a result, the non-magnetic portion 113Ca constitutes a first coupling member that mechanically couples the outer members 112 to each other, and the magnetic portion 113Cb constitutes a second coupling member that mechanically couples the first coupling member to the inner member 111.

[0029] 8 is a cross-sectional view showing the configuration of a rotor 102D of a motor according to a third modified example of the first embodiment. The rotor 102D includes a bridge member 113D instead of the bridge member 113 of FIG. 3. The bridge member 113D includes non-magnetic portions 113Da and 113Db made of a non-magnetic material, and a magnetic portion 113Dc made of the same magnetic material as the inner member 111 and the outer member 112. The magnetic portion 113Dc is formed integrally with the inner member 111 and extends to the vicinity of the adjacent outer member 112. One end of the non-magnetic portions 113Da and 113Db is mechanically coupled to the adjacent outer member 112, and the other end is mechanically coupled to the magnetic portion 113Dc. As a result, the non-magnetic portions 113Da, 113Db and the magnetic portion 113Dc constitute a first connecting member that mechanically connects the outer members 112 to each other, and a second connecting member that mechanically connects the first connecting member to the inner member 111.

[0030] 9 is a cross-sectional view showing the configuration of a rotor 102E of a motor according to a fourth modified example of the first embodiment. The rotor 102E includes a bridge member 113E instead of the bridge member 113 shown in FIG. 3. The bridge member 113E includes magnetic portions 113Ea and 113Eb made of the same magnetic material as the inner member 111 and the outer member 112, and a non-magnetic portion 113Ec made of a non-magnetic material. The non-magnetic portion 113Ec is mechanically coupled to the inner member 111 and extends to the vicinity of the adjacent outer member 112. One end of the magnetic portions 113Ea and 113Eb is integrally formed with the adjacent outer member 112, and the other end is mechanically coupled to the non-magnetic portion 113Ec. As a result, the magnetic portions 113Ea, 113Eb and the non-magnetic portion 113Ec constitute a first connecting member that mechanically connects the outer members 112 to each other, and a second connecting member that mechanically connects the first connecting member to the inner member 111.

[0031] FIG. 10 is a cross-sectional view showing the configuration of a rotor 102F of a motor according to a fifth modified example of the first embodiment. The rotor 102F includes a bridge member 113F instead of the bridge member 113 shown in FIG. 3. The bridge member 113F includes magnetic portions 113Fa, 113Fb, and 113Fd made of the same magnetic material as the inner member 111 and the outer member 112, and a non-magnetic portion 113Fc made of a non-magnetic material. The non-magnetic portion 113Fc extends a predetermined distance in the radial direction between adjacent magnets 105. One end of the magnetic portions 113Fa and 113Fb is integrally formed with the adjacent outer member 112, and the other end is mechanically coupled to the non-magnetic portion 113Fc. The magnetic portion 113Fd is integrally formed with the inner member 111 and is further mechanically coupled to the non-magnetic portion 113Fc. As a result, the magnetic portions 113Fa, 113Fb, 113Fd and the non-magnetic portion 113Fc constitute a first connecting member that mechanically connects the outer members 112 to each other, and a second connecting member that mechanically connects the first connecting member to the inner member 111.

[0032] FIG. 11 is a cross-sectional view showing the configuration of a rotor 102G of a motor according to a sixth modified example of the first embodiment. The rotor 102G includes a bridge member 113G instead of the bridge member 113 shown in FIG. 3. The bridge member 113G includes magnetic portions 113Ga, 113Gb, and 113Gd made of the same magnetic material as the inner member 111 and the outer member 112, and a non-magnetic portion 113Gc made of a non-magnetic material. One end of each of the magnetic portions 113Ga and 113Gb is integrally formed with the adjacent outer member 112, and the other end is mechanically coupled to the non-magnetic portion 113Gc. The magnetic portion 113Gd is integrally formed with the inner member 111 and extends to the vicinity of the adjacent outer member 112, where it is mechanically coupled to the non-magnetic portion 113Gc. As a result, the magnetic portions 113Ga, 113Gb, 113Gd and the non-magnetic portion 113Gc constitute a first connecting member that mechanically connects the outer members 112 to each other, and a second connecting member that mechanically connects the first connecting member to the inner member 111.

[0033] FIG. 12 is a table showing simulation results for the torque of a motor equipped with the rotor 102, 102B to 102G according to the first embodiment. A simulation was performed on the torque generated by a motor equipped with any of the rotors 102, 102A to 102G shown in FIGS. 3, 4, and 6 to 11. In the simulation, the motor had an outer diameter of 60 mm, and a constant current was supplied to the motor to operate it at a constant speed. The torque of the motor equipped with the rotor 102A according to the comparative example was set as the reference value, i.e., a torque increase rate of 0%. When any of the rotors 102, 102B to 102G according to the example was used, the torque was increased compared to the rotor 102A according to the comparative example. Furthermore, the torque increased most when the rotor 102B shown in FIG. 6 was used.

[0034] As described above, according to the first embodiment, by providing the bridge member 113 that is at least partially made of a non-magnetic material, it is possible to improve the efficiency of the motor by reducing the leakage magnetic flux more than in the case of FIG. 4 .

[0035] According to the first embodiment, the same torque as in the conventional motor can be generated with a smaller current than in the conventional motor. Furthermore, when the same torque as in the conventional motor is generated with the same current as in the conventional motor, the axial thickness of the rotor core 104 and the stator core 108 can be reduced compared to the conventional motor, thereby making the motor more compact than the conventional motor.

[0036] According to the first embodiment, it is possible to realize high efficiency and torque that could not be achieved by using only the general non-oriented electrical steel sheets used in motors.

[0037] FIG. 13 is a diagram showing the configuration of a part of the manufacturing apparatus for the motor 101 according to the first embodiment.

[0038] To manufacture the rotor core 104 and the stator core 108 of the motor 101, a method of constructing a magnetic material using a so-called 3D printing technology called additive manufacturing (AM method) may be used. There are several methods for forming structures using metal powder, but one example is a method of forming the rotor core 104 and the stator core 108 using directed energy deposition (DED), in which a laser beam, an electron beam, or a plasma arc is used as a heat source, metal powder is sprayed from a nozzle in a concentrated manner, and the metal is melted and sprayed.

[0039] FIG. 13 shows a directed energy deposition apparatus 200. When forming the inner member 111 and outer member 112 of FIG. 2, powder 221 primarily composed of iron is supplied from a first nozzle 201 onto a substrate 210. The powder 221 is melted using a laser beam 204 or the like focused by a lens 203 to form a molded object 223. The powder is repeatedly melted and formed while moving in a radial direction (e.g., the X direction). When forming the bridge member 113 of FIG. 2, the nozzle is switched to a second nozzle 202, and non-magnetic powder 222 is supplied onto the substrate 210. The powder 222 is melted using a laser beam 204 or the like to form a molded object 223. The powder is repeatedly melted and formed while moving in a radial direction. Holes are provided at positions where magnets 105 are inserted. This forms one layer of the rotor core 104. Next, moving in the Z direction, the supply, melting, and forming of metal powder are similarly repeated on this layer to form the same configuration, and these steps are repeated to stack the layers in the desired axial direction to form rotor core 104. Finally, magnets 105 are inserted into the holes in rotor core 104 and fixed with adhesive, thereby completing rotor 102.

[0040] To magnetize the magnets 105, the magnets 105 may be inserted into the holes in the rotor core 104, the rotor 102 may be placed in a magnetizing yoke, and a large current may be supplied to the magnetizing yoke. Alternatively, the magnetized magnets 105 may be inserted into the holes in the rotor core 104.

[0041] As described above, the non-magnetic material may include a non-metal or a metal. When a non-metallic non-magnetic material is used, eddy currents are not generated even when magnetic flux interlinks, and therefore eddy current loss is not generated. When a metallic non-magnetic material is used, it is easy to shape the material by melting and solidifying metal powder.

[0042] Instead of powder material, filaments or pellets may be used to form the inner member 111, outer member 112, and bridge member 113.

[0043] Instead of the laser beam 204, an electron beam or a plasma arc may be used as the heat source.

[0044] By using the AM method in this way, it is possible to join different materials to form a robust rotor core 104. Furthermore, if the magnetic material is also formed at the same time using the AM method, it is possible to form an even more integrally formed rotor 102 with increased mechanical strength.

[0045] Furthermore, although directed energy deposition has been shown as a method for forming the rotor core 104 and the stator core 108, other methods may be used depending on the material and application. For example, the inner member 111 and the outer member 112 made of a magnetic material may be formed using laser cladding (build-up welding), and then the bridge member 113 may be formed on top of them by build-up and coating the outer periphery with a non-magnetic material.

[0046] Rotors 102B-102G can also be fabricated by additive manufacturing using directed energy deposition apparatus 200 of FIG.

[0047] Second Embodiment Fig. 14 is a cross-sectional view showing the configuration of a rotor 102H of a motor according to a second embodiment. The rotor 102H includes a bridge member 113H instead of the bridge member 113 of Fig. 3. The bridge member 113H includes a filler material that fills the space between a pair of adjacent magnets 105 of the multiple magnets 105 along the circumferential direction of the rotor core 104. The filler material further mechanically couples a pair of outer members 112, each of which is located outside the pair of magnets 105 as viewed from the rotation shaft 106, to the inner member 111. The filler material is made of a non-magnetic material.

[0048] Although bridge member 113H in Fig. 14 is formed to be wider than connecting members 131 and 132 in Fig. 3, it is made of a non-magnetic material and therefore has little effect on the magnetic flux. Therefore, like motor 101 including rotor 102 in Fig. 3, a motor including rotor 102H in Fig. 14 can improve efficiency by reducing leakage magnetic flux compared to the case in Fig. 4.

[0049] Furthermore, the bridge member 113H in FIG. 14 is formed to be wider than the connecting members 131 and 132 in FIG. 3, thereby improving the mechanical strength compared to the case in FIG. 3, and realizing a rotor with high rigidity that can withstand centrifugal force during high-speed rotation.

[0050] The rotor 102H of FIG. 14 can also be manufactured by additive manufacturing using the directed energy deposition apparatus 200 of FIG.

[0051] [Third Embodiment] Fig. 15 is a longitudinal sectional view showing the configuration of a motor 101I according to a third embodiment. Fig. 16 is a transverse sectional view showing the configuration of a motor 101I according to the third embodiment.

[0052] The motor 101I includes a rotor 102I instead of the rotor 102 in Figures 1 and 2. Other components of the motor 101I are configured similarly to the corresponding components of the motor 101 in Figures 1 and 2.

[0053] In FIG. 16, the housing 110 is omitted for simplicity of illustration.

[0054] The rotor 102I includes a rotor core 104I, a plurality of magnets 105, and a rotating shaft 106. The rotor core 104I includes a plurality of outer members 112I, an inner member 111I, and a plurality of bridge members 113I. As will be described later, the rotor core 104I includes a plurality of electromagnetic steel plates stacked in the direction of the rotating shaft 106.

[0055] Fig. 17 is an enlarged view showing the configuration of the bridge member 113I in Fig. 16. Each of the plurality of bridge members 113 includes a first connecting member 131I, a second connecting member 132I, and a filler 133.

[0056] The first connecting member 131I mechanically connects a pair of adjacent outer members 112, among the multiple outer members 112, along the circumferential direction of the rotor core 104I. The second connecting member 132I mechanically connects the first connecting member 131I to the inner member 111. The connecting members 131I and 132I are made of the same magnetic material as the inner member 111 and the outer member 112. The connecting members 131I and 132I each have widths w1 and w2 that are smaller than the width that can be formed by ordinary punching, for example, a width smaller than 0.3 mm. The connecting members 131I and 132I each have widths w1 and w2 of, for example, 0.1 to 0.2 mm.

[0057] The filler 133 fills the space between a pair of adjacent magnets 105 of the multiple magnets 105 along the circumferential direction of the rotor core 104I. The filler 133 further mechanically couples, to the inner member 111, a pair of the multiple outer members 112 that are respectively provided outside the pair of magnets 105 as viewed from the rotation shaft 106. The filler 133 is a non-magnetic material, for example, a resin or an adhesive.

[0058] One electromagnetic steel plate constituting the rotor core 104I is formed to integrally include portions corresponding to the inner member 111I, outer member 112I, and connecting members 131I and 132I in FIG. 17 . The electromagnetic steel plate may be punched out, for example. Furthermore, a processing method such as wire cutting may be used to form the thin connecting members 131I and 132I. Multiple electromagnetic steel plates formed in this manner are stacked in the direction of the rotation axis 106 and fixed to each other by adhesive or caulking. Next, magnets 105 are inserted into the holes in the electromagnetic steel plate, and filler material 133 is filled in the vicinity of the connecting members 131I and 132I, thereby forming the rotor 102I.

[0059] FIG. 18 is a table showing simulation results for the torque of a motor including the rotor 102I according to the third embodiment. A simulation was performed on the torque generated by a motor including the rotor 102B of FIG. 4 or the rotor 102I of FIG. 17. The width of the connecting member in the rotor 102B of FIG. 4 was used as a reference value (comparison example), and the width of the connecting member in the rotor 102I of FIG. 17 was changed to 0.5 times (Example 1), 0.3 times (Example 2), 0.2 times (Example 3), and 0.1 times (Example 4). In the simulation, the motor had an outer diameter of 60 mm, and a constant current was supplied to the motor to operate it at a constant speed. In all cases, Examples 1 to 4 produced greater torque than the comparative example. Furthermore, comparing Examples 1 to 4, the torque increased as the width of the connecting member decreased.

[0060] FIG. 19 is a cross-sectional view showing the configuration of a rotor 102J of a motor according to a modified example of the third embodiment. The rotor 102J includes a bridge member 113J instead of the bridge member 113I shown in FIG. 17. The bridge member 113J includes reinforcing members 134a-134c instead of, or in addition to, the filler 133 shown in FIG. 17. The reinforcing members 134a-134c may be made of, for example, nonmagnetic stainless steel. The reinforcing members 134a-134c are provided to surround and reinforce the connecting members 131I and 132I. It may be difficult to provide sufficient rigidity using only the filler 133 made of resin or adhesive. Therefore, the reinforcing members 134a-134c may be inserted near the connecting members 131I and 132I from above and below, and then the reinforcing members 134a-134c may be fitted and bonded to each other. The bridge member 113J mechanically connects the outer members 112I to the inner member 111I via the filler 133 and the reinforcing members 134a to 134c, thereby improving the mechanical strength of the rotor 102J.

[0061] According to the third embodiment, the bridge member 113I includes the connecting members 131I and 132I made of a magnetic material. Therefore, portions corresponding to the inner member 111I, the outer member 112I, and the connecting members 131I and 132I can be integrally formed on a single electromagnetic steel sheet, and the rotor core 104I can be constructed by stacking a plurality of electromagnetic steel sheets. Furthermore, according to the third embodiment, by making the widths of the connecting members 131I and 132I smaller than those in FIG. 4 , leakage magnetic flux can be reduced more than in the case of FIG. 4 , thereby improving motor efficiency. Furthermore, according to the third embodiment, even if the widths of the connecting members 131I and 132I are reduced, a highly rigid rotor that can withstand centrifugal force during high-speed rotation can be realized by filling the connecting members 131I and 132I with the filler 133.

[0062] [Fourth Embodiment] Figure 20 is a cross-sectional view showing the configuration of a motor 101K according to a fourth embodiment. The motor 101K includes a rotor 102K instead of the rotor 102 in Figure 2. The rotor 102K includes a rotor core 104K, a plurality of magnets 105K, and a rotating shaft 106. The other components of the motor 101K are configured similarly to the corresponding components of the motor 101 in Figures 1 and 2.

[0063] FIG. 21 is an enlarged view showing the configuration of the outer member 112K and the bridge member 113I of FIG.

[0064] The rotor core 104K includes an inner member 111K, multiple outer members 112K, and multiple bridge members 113K. The multiple outer members 112K are each located outside the multiple magnets 105K when viewed from the rotation shaft 106. The inner member 111K is located closer to the rotation shaft 106 than the multiple outer members 112K. Here, "closer to the rotation shaft 106" means that the minimum distance to the rotation shaft 106 is smaller, and the inner member 111K may be partially farther from the rotation shaft 106 than the outer members 112K. The multiple bridge members 113K mechanically couple the multiple outer members 112K to the inner member 111K. The inner member 111K and the outer member 112K are made of a magnetic material. Each of the multiple bridge members 113K is at least partially made of a non-magnetic material.

[0065] Each of the multiple magnets 105K is formed so that its longitudinal direction is along the radial direction of the rotor core 104 in a cross section perpendicular to the rotation axis 106. Each of the multiple magnets 105K is arranged so that its north pole and south pole face the adjacent magnet 105K. The north pole of one magnet 105K faces the north pole of the adjacent magnet, and the south pole of one magnet 105K faces the south pole of the adjacent magnet. The rotor core 104 has holes for accommodating the magnets 105K, and the holes have gaps 141 to 143 that act as flux barriers and provide magnetic resistance.

[0066] Each of the plurality of bridge members 113K mechanically connects each of the plurality of outer members 112K to the inner member 111K so that the outer member 112K is spaced apart from the magnet 105K. Each of the plurality of bridge members 113K is made of a non-magnetic material.

[0067] 22 is a schematic diagram showing magnetic flux generated in a rotor 102L of a motor according to a comparative example. Instead of mechanically connecting an outer member 112K to an inner member 111K via a bridge member 113K made of a non-magnetic material, the rotor 102L includes an inner member 111L and an outer member 112L that are integrally formed. In this case, part of the magnetic flux 161 generated by the magnet 105L travels along the outer member 112L and becomes leakage magnetic flux 162.

[0068] Figure 23 is a schematic diagram showing magnetic flux generated in a rotor 102K of a motor 101K according to the fourth embodiment. Because the rotor 102K includes a bridge member 113K made of a non-magnetic material, magnetic flux 164 traveling from the magnet 105K to the bridge member 113K is reduced compared to the leakage magnetic flux 162 in the case of Figure 22. Therefore, with the motor 101K according to the fourth embodiment, the leakage magnetic flux is reduced compared to the case of Figure 22, thereby improving efficiency.

[0069] Furthermore, according to the fourth embodiment, the rotor core 104K is provided with an outer member 112K, and as a result, the magnetic flux 163 from the winding 109 passes through the outer member 112K, reducing the magnetic flux passing through the magnet 105K (see Figure 23), thereby making it less likely that demagnetization of the magnet 105K will occur.

[0070] The rotor 102K of FIG. 20 can also be manufactured by additive manufacturing using the directed energy deposition apparatus 200 of FIG.

[0071] Other Embodiments The disclosed embodiments and modifications may be combined as appropriate.

[0072] At least a portion of the bridge member may be made of a magnetic material having a lower relative permeability and / or saturation magnetic flux density than the magnetic materials of the inner and outer members, instead of a non-magnetic material. Examples of such magnetic materials include amorphous soft magnetic materials, alloy dust cores such as Permalloy and Sendust, and the like. Coating magnetic powder with an insulating material and then compacting and molding the powder results in fine gaps, resulting in a low-permeability material. Using bridge members made at least partially of such magnetic materials also improves efficiency by reducing leakage flux, just as using bridge members made at least partially of non-magnetic materials.

[0073] The stator core may be manufactured by additive manufacturing, or may be manufactured by stacking a plurality of electromagnetic steel sheets.

[0074] In each embodiment, a motor having a magnet on the rotor and a winding on the stator has been described, but the principles described can also be applied to a motor having a winding on the rotor and a magnet on the stator.

[0075] The described embodiments are not limited to motors and can also be applied to other electromechanical devices, such as generators.

[0076] Summary of the Embodiments An electromechanical device according to each aspect of the present disclosure is configured as follows.

[0077] An electric machine device according to a first aspect of the present disclosure comprises: a stator core; a rotor core arranged inside the stator core so as to be rotatable around a rotation axis; a plurality of windings wound around the stator core; and a plurality of magnets arranged on the rotor core, wherein the rotor core comprises a plurality of outer members each arranged outside the plurality of magnets when viewed from the rotation axis; an inner member arranged closer to the rotation axis than the plurality of outer members; and a plurality of bridge members each mechanically connecting the plurality of outer members to the inner member, wherein the plurality of outer members and the inner member are made of magnetic material, and each of the plurality of bridge members is made at least partially of non-magnetic material.

[0078] According to the second aspect of the present disclosure, in the electric mechanical device of the first aspect, each of the plurality of magnets is formed so as to have a longitudinal direction perpendicular to the radial direction of the rotor core in a cross section perpendicular to the rotation axis, and is arranged so that one of the north pole and south pole faces the rotation axis and the other of the north pole and south pole faces the stator core, each of the plurality of bridge members comprises: a first connecting member that mechanically connects a pair of outer members that are adjacent to each other along the circumferential direction of the rotor core among the plurality of outer members; and a second connecting member that mechanically connects the first connecting member to the inner member, and at least a portion of the first connecting member is made of the non-magnetic material.

[0079] According to a third aspect of the present disclosure, in the electromechanical device according to the second aspect, at least a portion of the second connecting member is made of the non-magnetic material.

[0080] According to a fourth aspect of the present disclosure, in the electric machine device according to the second or third aspect, the rotor core is formed by an additive manufacturing method.

[0081] According to the fifth aspect of the present disclosure, in the electric mechanical device of the first aspect, each of the plurality of magnets is formed to have a longitudinal direction perpendicular to the radial direction of the rotor core in a cross section perpendicular to the rotation axis, and is arranged so that one of the north and south poles faces the rotation axis and the other of the north and south poles faces the stator core, each of the plurality of bridge members is a filler filled in the space between a pair of magnets among the plurality of magnets that are adjacent to each other along the circumferential direction of the rotor core, and comprises a filler that mechanically connects a pair of outer members among the plurality of outer members that are each arranged outside the pair of magnets as viewed from the rotation axis to the inner member, and the filler is made of the non-magnetic material.

[0082] According to an electromechanical device according to a sixth aspect of the present disclosure, in the electromechanical device according to the fifth aspect, the filler material includes a resin or an adhesive.

[0083] According to an electric machine device according to a seventh aspect of the present disclosure, in the electric machine device according to the fifth or sixth aspect, the rotor core is formed by an additive manufacturing method.

[0084] According to an eighth aspect of the present disclosure, in the electric mechanical device of the sixth aspect, each of the plurality of bridge members further includes a first connecting member that mechanically connects a pair of outer members that are adjacent to each other along the circumferential direction of the rotor core among the plurality of outer members, and a second connecting member that mechanically connects the first connecting member to the inner member, the first and second connecting members being made of the magnetic material, and the first and second connecting members having a width less than 0.3 mm.

[0085] According to the ninth aspect of the present disclosure, in the electromechanical device of the eighth aspect, each of the plurality of bridge members further includes a reinforcing member arranged to surround the first and second connecting members, and each of the plurality of bridge members mechanically connects the plurality of outer members to the inner member via the filler material and the reinforcing member.

[0086] According to the electromechanical device of the tenth aspect of the present disclosure, in the electromechanical device of the eighth or ninth aspect, the rotor core includes a plurality of magnetic plates made of the magnetic material stacked in the direction of the rotation axis.

[0087] According to an eleventh aspect of the present disclosure, in the electric mechanical device of the first aspect, each of the plurality of magnets is formed to have a longitudinal direction along the radial direction of the rotor core in a cross section perpendicular to the rotation axis, and is arranged so that the north pole and south pole face adjacent magnets, each of the plurality of bridge members mechanically connects the plurality of outer members to the inner member so that the outer member is spaced from the magnet, and each of the plurality of bridge members is made of the non-magnetic material.

[0088] According to an electric machine device according to a twelfth aspect of the present disclosure, in the electric machine device according to the eleventh aspect, the rotor core is formed by an additive manufacturing method.

[0089] According to a thirteenth aspect of the present disclosure, an electric machine device comprises: a stator core; a rotor core arranged inside the stator core so as to be rotatable around a rotation axis; a plurality of windings wound around the stator core; and a plurality of magnets arranged on the rotor core, wherein the rotor core comprises: a plurality of outer members each arranged outside the plurality of magnets when viewed from the rotation axis; an inner member arranged closer to the rotation axis than the plurality of outer members; and a plurality of bridge members mechanically connecting the plurality of outer members to the inner members, wherein the plurality of outer members and the inner member are made of a first magnetic material; and each of the plurality of bridge members is made at least in part of a second magnetic material having a relative permeability lower than the relative permeability of the first magnetic material or a saturation magnetic flux density lower than the saturation magnetic flux density of the first magnetic material.

[0090] The present disclosure is applicable to various motors, such as industrial servo motors and drive motors for electric vehicles or plug-in hybrid vehicles.

[0091] DESCRIPTION OF SYMBOLS 101, 101I, 101K Motor 102, 102A to 102K Rotor 103 Stator 104, 104I, 104K Rotor core 105, 105K Magnet 106 Rotating shaft 107 Bearing 108 Stator core 109 Winding 110 Housing 111, 111I, 111K Inner member 112, 112I, 112K Outer member 113, 113I, 113K Bridge member 121 Yoke 122 Protrusion 131, 131I First connecting member 132, 132I Second connecting member 133 Filler 134a to 134c Reinforcing member 141 to 143 Void portion 200 Directed energy deposition device 201, 202 Nozzle 203 Lens 204 Laser light 210 Substrate 221, 222 Powder 223 Modeled object

Claims

1. An electric mechanical device comprising: a stator core; a rotor core provided inside the stator core so as to be rotatable about a rotation axis; a plurality of windings wound around the stator core; and a plurality of magnets provided on the rotor core, wherein the rotor core comprises a plurality of outer members each provided outside the plurality of magnets when viewed from the rotation axis, an inner member provided closer to the rotation axis than the plurality of outer members, and a plurality of bridge members mechanically connecting the plurality of outer members to the inner member, wherein the plurality of outer members and the inner member are made of magnetic material, and each of the plurality of bridge members is at least partially made of a non-magnetic material.

2. An electric machine device as described in claim 1, wherein each of the plurality of magnets is formed so as to have a longitudinal direction perpendicular to the radial direction of the rotor core in a cross section perpendicular to the rotation axis, and one of the N pole and S pole faces the rotation axis and the other of the N pole and S pole faces the stator core, and each of the plurality of bridge members comprises a first connecting member that mechanically connects a pair of outer members adjacent to each other along the circumferential direction of the rotor core among the plurality of outer members, and a second connecting member that mechanically connects the first connecting member to the inner member, and at least a portion of the first connecting member is made of the non-magnetic material.

3. The electromechanical device according to claim 2, wherein at least a portion of said second connecting member is made of said non-magnetic material.

4. The electromechanical device according to claim 2 or 3, wherein the rotor core is formed by additive manufacturing.

5. An electric machine device as described in claim 1, wherein each of the plurality of magnets is formed to have a longitudinal direction perpendicular to the radial direction of the rotor core in a cross section perpendicular to the rotation axis, and one of the N pole and S pole faces the rotation axis and the other of the N pole and S pole faces the stator core, and each of the plurality of bridge members is a filler that fills the space between a pair of magnets among the plurality of magnets that are adjacent to each other along the circumferential direction of the rotor core, and comprises a filler that mechanically connects a pair of outer members among the plurality of outer members that are each arranged outside the pair of magnets when viewed from the rotation axis to the inner member, and the filler is made of the non-magnetic material.

6. The electromechanical device according to claim 5, wherein the filler material includes a resin or an adhesive.

7. The electromechanical device according to claim 5 or 6, wherein the rotor core is formed by additive manufacturing.

8. An electromechanical device as described in claim 6, wherein each of the plurality of bridge members further comprises: a first connecting member that mechanically connects a pair of outer members adjacent to each other along the circumferential direction of the rotor core among the plurality of outer members; and a second connecting member that mechanically connects the first connecting member to the inner member, the first and second connecting members being made of the magnetic material, and the first and second connecting members having a width smaller than 0.3 mm.

9. The electromechanical device according to claim 8, wherein each of the plurality of bridge members further comprises a reinforcing member provided so as to surround the first and second connecting members, and each of the plurality of bridge members mechanically connects the plurality of outer members to the inner member via the filler material and the reinforcing member.

10. The electromechanical device according to claim 8 or 9, wherein the rotor core comprises a plurality of magnetic plates made of the magnetic material and stacked in the direction of the rotation axis.

11. An electromechanical device as described in claim 1, wherein each of the plurality of magnets is formed to have a longitudinal direction along the radial direction of the rotor core in a cross section perpendicular to the rotation axis, and is arranged so that a north pole and a south pole face adjacent magnets, each of the plurality of bridge members mechanically connects each of the plurality of outer members to the inner member such that the outer member is spaced from the magnet, and each of the plurality of bridge members is made of the non-magnetic material.

12. The electromechanical device of claim 11, wherein the rotor core is formed by additive manufacturing.

13. An electric mechanical device comprising: a stator core; a rotor core provided inside the stator core so as to be rotatable about a rotation axis; a plurality of windings wound around the stator core; and a plurality of magnets provided on the rotor core, wherein the rotor core comprises: a plurality of outer members each provided outside the plurality of magnets when viewed from the rotation axis; an inner member provided closer to the rotation axis than the plurality of outer members; and a plurality of bridge members mechanically connecting the plurality of outer members to the inner member, wherein the plurality of outer members and the inner member are made of a first magnetic material, and each of the plurality of bridge members is made at least partially of a second magnetic material having a relative permeability lower than the relative permeability of the first magnetic material or a saturation magnetic flux density lower than the saturation magnetic flux density of the first magnetic material.

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