Core unit and rotor

Abstract

This core unit comprises at least one core and a pipe. The at least one core is formed with a powder magnetic core hole penetrated in a first direction. The pipe extends in the first direction. Further, the pipe is inserted into the powder magnetic core hole. The core unit is thereby obtained that can maintain the shape of a powder magnetic core and improve the cooling performance of the core.

Description

[0001] The present disclosure relates to a core unit and a rotor. The present application claims priority based on Japanese Patent Application No. 2022-163885 filed on October 12, 2022, the entire content of which is incorporated herein by reference. BACKGROUND ART

[0002] Conventionally, core units including powder magnetic cores are known. For example, Patent Document 1 discloses a stator core composed of a powder magnetic core as an example of the core unit (see FIG. 2 in the same document). Citation List Patent Literature

[0003] Patent Document 1: JP2008-271713A SUMMARY Problems to be Solved

[0004] If, for example, tensile stress is generated in the powder magnetic core of the core unit, the powder magnetic core may become defective, making it difficult to maintain the shape of the core unit. In addition, the temperature of the core unit may rise due to iron loss, for example.

[0005] An object of the present disclosure is to provide a core unit and a rotor that can maintain the shape of the powder magnetic core and improve the cooling performance of the core. Solution to the Problems

[0006] A core unit according to at least one embodiment of the present disclosure is provided with: a core including at least one powder magnetic core having a powder magnetic core hole penetrating in a first direction; and a pipe extending in the first direction and inserted into the powder magnetic core hole.

[0007] A rotor according to at least one embodiment of the present disclosure is provided with: a ring unit including a plurality of the above-described core units, and a plurality of nonmagnetic bodies arranged alternately with the plurality of core units in a circumferential direction that is perpendicular to the first direction; and a pair of flanges respectively connected to both end portions of the ring unit in the first direction, each flange being configured to be connected to a rotational shaft extending in the first direction. Each flange has at least one flange hole communicating with an internal space of the pipe of each of the plurality of core units. Advantageous Effects

[0008] The present disclosure provides a core unit and a rotor that can maintain the shape of the powder magnetic core and improve the cooling performance of the core. BRIEF DESCRIPTION OF DRAWINGS

[0009] FIG. 1 is a schematic diagram of a core unit according to an embodiment. FIG. 2A is a schematic diagram of a core according to an embodiment. FIG. 2B is a schematic diagram of a core according to another embodiment. FIG. 3 is a schematic diagram showing a joint structure between a core and a pipe according to an embodiment. FIG. 4 is a schematic diagram showing a detailed structure of a pipe according to an embodiment. FIG. 5 is a schematic diagram showing a joint structure between a core and a pipe according to another embodiment. FIG. 6Ais a schematic diagram of a pipe according to an embodiment (first example). FIG. 6B is a schematic diagram of a pipe according to an embodiment (second example). FIG. 6C is a schematic diagram of a pipe according to an embodiment (third example). FIG. 7 is a schematic diagram of a rotor according to an embodiment. FIG. 8 is a schematic diagram showing a partial configuration of a ring unit according to an embodiment. FIG. 9 is a schematic diagram showing a magnetic geared electrical machine according to an embodiment. DETAILED DESCRIPTION

[0010] Embodiments of the present disclosure will be described below with reference to the accompanying drawings. It is intended, however, that unless particularly identified, dimensions, materials, shapes, relative positions, and the like of components described in the embodiments shall be interpreted as illustrative only and not intended to limit the scope of the present disclosure. For instance, an expression of relative or absolute arrangement such as “in a direction”, “along a direction”, “parallel”, “orthogonal”, “centered”, “concentric” and “coaxial” shall not be construed as indicating only the arrangement in a strict literal sense, but also includes a state where the arrangement is relatively displaced by a tolerance, or by an angle or a distance whereby it is possible to achieve the same function. For instance, an expression of an equal state such as “same” “equal” and “uniform” shall not be construed as indicating only the state in which the feature is strictly equal, but also includes a state in which there is a tolerance or a difference that can still achieve the same function. Further, for instance, an expression of a shape such as a rectangular shape or a cylindrical shape shall not be construed as only the geometrically strict shape, but also includes a shape with unevenness or chamfered corners within the range in which the same effect can be achieved. On the other hand, an expression such as “comprise”, “include”, “have”, “contain” and “constitute” are not intended to be exclusive of other components. The same configurations are indicated by the same reference signs and may not be described again in detail.

[0011] <1. Overview of core unit 10> FIG. 1 is a schematic exploded perspective view of a core unit 10 according to an embodiment of the present disclosure. The core unit 10, which may be incorporated into an armature, is provided with a core 60 extending in the first direction. In the case where the core unit 10 is incorporated into a stator as an example of the armature, an armature coil may be wound on the core 60. In the case where the core unit 10 is incorporated into a rotor 30 (see FIG. 7) as an example of the armature, an armature coil may not be wound on the core 60. The first direction can be any direction, and it can be the vertical direction, the horizontal direction, or a direction intersecting the vertical and horizontal directions.

[0012] An insertion hole 68 is formed in the central portion of the core 60. The insertion hole 68 illustrated in FIG. lisa through hole penetrating in the first direction, but the present disclosure is not limited thereto. The insertion hole 68 may be closed on one side in the first direction and open only on the other side (as will be described later in detail). The core unit 10 is further provided with a pipe 80 extending in the first direction, and the pipe 80 is inserted into the insertion hole 68 of the core 60. The fitting between the pipe 80 and the insertion hole 68 may be a tight fit, an intermediate fit, or a gap fit. Whichever type of fitting is employed, an adhesive 9 (see FIG. 3) may be interposed between the inner peripheral surface that defines the insertion hole 68 and the pipe 80. The pipe 80 (see FIG. 1) inserted into the insertion hole 68 supports the core 60.

[0013] In the example of FIG. 1, the insertion hole 68 is circular when viewed in the first direction and the pipe 80 is cylindrical, but the present disclosure is not limited thereto. In another embodiment, the insertion hole 68 may be rectangular when viewed in the first direction, in which case the pipe 80 is formed in a square cylinder shape. The following description will focus primarily on an example where the pipe 80 is inserted into a single circular insertion hole 68.

[0014] In the example of FIG. 1, a single insertion hole 68 is formed, but the present disclosure is not limited thereto. In another embodiment, two insertion holes 68 may be arranged at intervals in the direction perpendicular to the first direction (not shown). In this case, the two insertion holes 68 may both be through holes penetrating in the first direction. Alternatively, two insertion holes 68 may be arranged at intervals in the first direction. In any embodiment, two pipes 80 may be inserted into two insertion holes 68, respectively.

[0015] <2. Detailed structure of core 60> FIGs. 2A and 2B are each a schematic diagram showing a core 60A, 60B (60) according to some embodiments of the present disclosure. The core 60A, 60B (60) includes at least one powder magnetic core 70. The core 60 A illustrated in FIG. 2 A includes a plurality of powder magnetic cores 70 laminated consecutively in the first direction. The core 60B illustrated in FIG. 2B includes a steel sheet laminate 79 containing a plurality of steel sheets 77 laminated consecutively in the first direction, and a pair of powder magnetic cores 70 disposed on both sides of the steel sheet laminate 79 in the first direction.

[0016] A powder magnetic core hole 75 penetrating in the first direction is formed in the central portion of each powder magnetic core 70 illustrated in FIGs. 2A and 2B. The powder magnetic core hole 75 is a constituent element of the insertion hole 68. In the example of FIG. 2 A, the insertion hole 68 A (68) formed by the plurality of the powder magnetic core holes 75 is a through hole penetrating in the first direction. In the example of FIG. 2B, a steel sheet hole 78 is formed in the central portion of each steel sheet 77, and the insertion hole 68 is formed by the plurality of steel sheet holes 78 and two powder magnetic core holes 75. In the example of FIG. 2B, similarly, the insertion hole 68 is a through hole penetrating in the first direction.

[0017] With the above configuration, since the powder magnetic core hole 75 is formed in the powder magnetic core 70 for insertion of the pipe 80, air flowing through the internal space of the pipe 80 can cool the core 60. This suppresses the temperature rise of the core 60 caused by the generation of eddy current, for example. Further, the powder magnetic core 70 may be damaged due to the generation of tensile stress in the first direction, for example. In this regard, with the above configuration, since the pipe 80 is inserted into the powder magnetic core hole 75, a fragmented powder magnetic core 70 is prevented from falling off the core 60 even if the powder magnetic core 70 is damaged. Thus, it is possible to achieve the core unit 10 that can maintain the shape of the powder magnetic core 70 and improve the cooling performance of the core 60.

[0018] The cause of the temperature rise of the core 60 is not limited to the generation of eddy current. For example, in an embodiment where an armature coil is wound on the core 60, heat generated by energization of the armature coil is transferred to the core 60, causing the temperature rise of the core 60. Also in this embodiment, the cooling performance of the core 60 is expected to improve by air flowing through the internal space of the pipe 80 inserted into the powder magnetic core hole 75. The insertion hole 68 is not limited to a through hole penetrating in the first direction. More specifically, the steel sheets 77 of FIG. 2B may have no steel sheet holes 78. In this case, two insertion holes 68 are formed by the two powder magnetic cores 70 disposed on both sides of the steel sheet laminate 79. That is, two insertion holes 68 are arranged at intervals in the first direction. The two insertion holes 68 are both closed by the steel sheet laminate 79 (i.e., one side of each insertion hole 68 in the first direction is closed by the steel sheet laminate 79). In this embodiment, two pipes 80 are inserted into the two powder magnetic core holes 75, respectively. Even in this case, the cooling performance of the core 60 is expected to improve because air can flow through the internal space of the pipe 80. This also prevents a fragmented powder magnetic core 70 from falling off the core 60.

[0019] Although not essential in the present disclosure, in the examples of FIGs. 2A and 2B, a single pipe 80 that is longer in the first direction than the core 60A, 60B (60) is inserted from one end portion to the other end portion of the core 60. With the above configuration, since the pipe 80 is inserted to pass through the core 60, the pipe 80 supports the core 60 more firmly and improves the mechanical strength of the core unit 10.

[0020] In the example of FIG. 2A, as described above, the core 60A (60) includes a plurality of powder magnetic cores 70 laminated consecutively in the first direction, and a single pipe 80 is inserted into the respective powder magnetic core holes 75. In the example of FIG. 2B, the core 60B (60) includes two powder magnetic cores 70 arranged in the first direction with the steel sheet laminate 79 in between, and a single pipe 80 is inserted into the respective powder magnetic core holes 75. With the above configuration, since the core 60 includes a plurality of powder magnetic cores 70, it is possible to downsize each powder magnetic core 70 forming the core 60. This simplifies the work of inserting each powder magnetic core 70 into the pipe 80 during the assembly process of the core 60. In addition, downsizing the powder magnetic core 70 reduces the molding pressure required for a molding machine used in the molding process of the powder magnetic core 70, simplifying the production of the powder magnetic core 70. As described above, the steel sheets 77 of FIG. 2B may have no steel sheet holes 78, and two pipes 80 may be inserted into two powder magnetic cores 70 disposed on both end portions of the core 60. In this case, each pipe 80 is shorter than the core 60 in the first direction. Also in this embodiment, since the core 60 includes a plurality of powder magnetic cores 70, it is possible to downsize each powder magnetic core 70. Therefore, the above advantages can be obtained.

[0021] The pipe 80 according to an embodiment of the present disclosure is preferably formed of a non-magnetic material, and is more preferably formed of a non-magnetic metal material. Examples of the non-magnetic metal material include aluminum, austenitic stainless steel, and copper. With the above configuration, since the pipe 80 is formed of a non-magnetic material, it is possible to suppress the hysteresis loss caused by magnetization of the pipe 80 and maintain the magnetic flux modulating function of the core 60. Additionally, if the pipe 80 is formed of a non-magnetic metallic material, it is possible to improve the thermal conductivity of the pipe 80 and improve the thermal transfer from the powder magnetic core 70 to the pipe 80. The pipe 80 may be formed of a non-metallic, non-magnetic material such as a resin material. Even in this case, the above advantages of suppressing the hysteresis loss caused by magnetization of the pipe 80 and maintaining the magnetic flux modulating function of the core 60 can be obtained.

[0022] In the example of FIG. 2B, the powder magnetic core 70 that forms an end portion of the core 60 on one side in the first direction is a one-side powder magnetic core 71, and the powder magnetic core 70 that forms an end portion on the other side is an other-side powder magnetic core 72. The one-side powder magnetic core 71 is located on one side of the steel sheet laminate 79 in the first direction, and the other-side powder magnetic core 72 is located on the other side of the steel sheet laminate 79 in the first direction. With the above configuration, the one-side powder magnetic core 71 suppresses a leakage magnetic flux that tends to occur in the end portion of the core 60 on one side, thereby suppressing the generation of eddy current in the core 60. Accordingly, the temperature rise of the core 60 can be suppressed. Also, the other-side powder magnetic core 72 suppresses the temperature rise of the core 60 for the same reason. At least one powder magnetic core 70 may be further placed between the one-side powder magnetic core 71 and the steel sheet laminate 79. Similarly, at least one powder magnetic core 70 may be further placed between the other-side powder magnetic core 72 and the steel sheet laminate 79. In any embodiment, the above advantages can be obtained.

[0023] The thickness of the pipe 80 according to an embodiment of the present disclosure is 10% or less of the minimum inner diameter of the powder magnetic core hole 75. With the above configuration, since the pipe 80 is made thinner, heat exchange between the air flowing through the internal space of the pipe 80 and the powder magnetic core 70 is promoted, and the cooling performance of the core unit 10 is expected to improve.

[0024] <3. Insulator 110> Referring to FIG. 1 again, the core unit 10 according to an embodiment of the present disclosure is further provided with an insulator 110 disposed so as to be stacked on an end portion of the core 60 in the first direction. The insulator 110 forms an end portion of the core unit 10 in the first direction. The insulator 110 illustrated in FIG. 1 is a plate-like structure with thickness in the first direction. As an example, the material forming the insulator 110 may be a fiber-reinforced composite material (FRP; Fiber Reinforced Plastics), more specifically, a glass fiber-reinforced plastic (GFRP; Glass Fiber Reinforced Plastics). Other examples of the material forming the insulator 110 include resin materials or ceramic materials. In the example of FIG. 1, the insulator 110 is disposed on both sides of the core 60 in the first direction. An insulator hole 115 penetrating in the first direction is formed in the central portion of each insulator 110, and each insulator hole 115 faces the insertion hole 68 of the core 60 in the first direction. The pipe 80 according to an embodiment of the present disclosure is inserted into the insulator hole 115 as well as the insertion hole 68. More specifically, as an example, an end portion of the pipe 80 in the first direction is accommodated in the insulator hole 115. In other words, the pipe 80 does not protrude from the insulator hole 115 to the opposite side from the core unit 10. The fitting between the pipe 80 and the insulator hole 115 may be a tight fit, an intermediate fit, or a gap fit.

[0025] With the above configuration, the pipe 80 is inserted into the insulator hole 115 of the insulator 110 stacked on the end portion of the core 60, making it difficult for the pipe 80 to be removed from the powder magnetic core hole 75. Thus, the mechanical strength of the core unit 10 is improved. Further, the insulator 110 suppresses a leakage magnetic flux that tends to occur in the end portion of the core 60 in the first direction, thereby suppressing the generation of eddy current in the core 60. Accordingly, the temperature rise of the core 60 can be suppressed. Even if the powder magnetic core 70 is damaged, the insulator 110 stacked on the end portion of the core 60 serves to prevent the fragmented powder magnetic core 70 from falling off the core 60.

[0026] One end 87 of the pipe 80 on one side in the first direction may be located on a side opposite one side (e.g., on the other side) relative to an end 111 of the insulator 110 on the one side (see FIGs. 3 and 5). In an embodiment where the core unit 10 is incorporated into a rotor 30 (see FIG. 7), which will be described below, the insulator 110 is sandwiched between an end ring 31, a component of the rotor 30, and the core 60. In this regard, when the end 87 of the pipe 80 is located on the other side relative to the end 111 of the insulator 110, it is possible to avoid contact between the end 87, which is accommodated in the insulator hole 115, and the end ring 31, which may be made of metal. This prevents unintended conduction between the core 60 and the end ring 31. However, the present disclosure does not exclude embodiments where the end 87 of the pipe 80 and the end 111 of the insulator 110 are in the same position in the first direction (see FIG. 4). The present disclosure also does not exclude embodiments where the end 87 of the pipe 80 is located on one side relative to the end 111 of the insulator 110 (not shown).

[0027] <4. Joint structure between core 60A (60) and pipe 80> FIG. 3 is a schematic cross-sectional view showing a joint structure between the core 60A (60) and the pipe 80 according to an embodiment of the present disclosure. The abovedescribed core 60A shown in this figure has an insulator 110 stacked in the first direction.

[0028] The powder magnetic core 70 has a powder magnetic core inner peripheral surface 76 defining the powder magnetic core hole 75, the insulator 110 has an insulator inner peripheral surface 116 defining the insulator hole 115, and the pipe 80 has a pipe outer peripheral surface 89. The pipe 80 illustrated in FIG. 3 is inserted into the powder magnetic core hole 75 and the insulator hole 115. The pipe outer peripheral surface 89 has a portion that overlaps in the axial direction with the powder magnetic core inner peripheral surface 76 and a portion that overlaps in the axial direction with the insulator inner peripheral surface 116. The axial direction of the pipe 80 coincides with the first direction.

[0029] In the example of FIG. 3, an adhesive 9 is interposed between the powder magnetic core inner peripheral surface 76 and the pipe outer peripheral surface 89. In the illustrated example, the adhesive 9 extends over substantially the entire length of the core 60A in the first direction. More specifically, the adhesive 9 is interposed between the pipe outer peripheral surface 89 and the powder magnetic core inner peripheral surfaces 76 of all powder magnetic cores 70 constituting the core 60A. However, the present disclosure is not limited to the adhesive 9 being interposed only between the pipe outer peripheral surface 89 and the powder magnetic core inner peripheral surface 76. The adhesive 9 may be interposed between the insulator inner peripheral surface 116 and the pipe outer peripheral surface 89 as shown in the same figure. The adhesive 9 is preferably insulating, more preferably insulating and non magnetic.

[0030] With the above configuration, since the adhesive 9 is interposed between the pipe outer peripheral surface 89 and the powder magnetic core inner peripheral surface 76, the fragmented powder magnetic core 70 caused by damage is prevented from falling off the core 60. Additionally, since the pipe outer peripheral surface 89 and the powder magnetic core inner peripheral surface 76 can adhere to each other via the adhesive 9, the thermal conductivity from the powder magnetic core 70 to the pipe 80 is further improved. The core unit 10 may not include the insulator 110. Further, the adhesive 9 may be placed on the core 60B (FIG. 2B) instead of the core 60A. More specifically, the adhesive 9 may be placed between the inner peripheral surface forming the insertion hole 68B (i.e., the powder magnetic core inner peripheral surface 76 and a steel sheet inner peripheral surface 176 described below) and the pipe outer peripheral surface 89. Also in this embodiment, the above advantages can be obtained.

[0031] FIG. 4 is a schematic diagram showing a detailed structure of a pipe 80A (80) as an example of the pipe 80. The pipe 80A in this figure is inserted into the insertion hole 68A of the core 60A. The pipe outer peripheral surface 89A (89) of the pipe 80A has at least one of an outer peripheral surface recess 181 or an outer peripheral surface protrusion 183. In this figure, both the outer peripheral surface recess 181 and the outer peripheral surface protrusion 183 are provided. As a more detailed example, a plurality of outer peripheral surface recesses 181 are arranged at intervals in the first direction, and a plurality of outer peripheral surface protrusions 183 are arranged at intervals in the first direction. The outer peripheral surface recess 181 or the outer peripheral surface protrusion 183 is formed by blasting, knurling, or machining, such as line engraving, on the pipe outer peripheral surface 89A. At least one of the outer peripheral surface recess 181 or the outer peripheral surface protrusion 183 may be formed over the entire surface of the pipe outer peripheral surface 89, or may be formed only in a portion of the pipe outer peripheral surface 89Athat overlaps in the axial direction with the powder magnetic core inner peripheral surface 76. The pipe outer peripheral surface 89A may have only one of the outer peripheral surface recess 181 or the outer peripheral surface protrusion 183. Further, the outer peripheral surface protrusion 183 may be a separate material from the pipe outer peripheral surface 89. With the above configuration, the amount of the adhesive 9 interposed between the pipe outer peripheral surface 89A (89) and the powder magnetic core inner peripheral surface 76 is increased by providing at least one of the outer peripheral surface recess 181 or the outer peripheral surface protrusion 183. This further prevents the fragmented powder magnetic core 70 caused by damage from falling off the core 60A (60).

[0032] Although not essential in the present disclosure, the pipe 80A (80) may further have a pipe inner peripheral surface 86 and at least one of an inner peripheral surface protrusion 861 or an inner peripheral surface recess 863 provided on the pipe inner peripheral surface 86. In the example of FIG. 4, both the inner peripheral surface protrusion 861 and the inner peripheral surface recess 863 are provided. As an example, the inner peripheral surface protrusion 861 is a fin that is a separate material from the pipe inner peripheral surface 86 and extends over the entire circumferential length of the pipe 80A. A plurality of inner peripheral surface protrusions 861 are arranged at intervals in the axial direction. The inner peripheral surface recess 863 is a groove in the pipe inner peripheral surface 86 and extends over the entire circumferential length of the pipe 80A. A plurality of inner peripheral surface recesses 863 are arranged at intervals in the axial direction. The inner peripheral surface protrusion 861 is preferably provided in a portion of the pipe inner peripheral surface 86 that overlaps in the axial direction with the insertion hole 68A of the core 60A, and the same applies to the inner peripheral surface recess 863. The pipe inner peripheral surface 86 may have only one of the inner peripheral surface protrusion 861 or the inner peripheral surface recess 863. The inner peripheral surface protrusion 861 or the inner peripheral surface recess 863 may be provided in a portion of the pipe inner peripheral surface 86 that overlaps in the axial direction with the insulator inner peripheral surface 116 (in the example of FIG. 4, the inner peripheral surface recesses 863 are provided in this portion of the pipe inner peripheral surface 86). The pipe 80 with at least one of the inner peripheral surface protrusion 861 or the inner peripheral surface recess 863 may be, for example, a rifle tube.

[0033] With the above configuration, heat exchange between the pipe inner peripheral surface 86 and air is promoted, so that the cooling performance of the core 60A (60) is improved. The present disclosure is not limited to the pipe 80A being inserted into the insertion hole 68A of the core 60A. The pipe 80A may be inserted into the insertion hole 68B of the core 60B (see FIG. 2B). In this case, the inner peripheral surface protrusion 861 and the inner peripheral surface recess 863 may be arranged to overlap in the axial direction with the inner peripheral surface forming the insertion hole 68B (the powder magnetic core inner peripheral surface 76 and a steel sheet inner peripheral surface 176 described below).

[0034] <5. Joint structure between core 60B (60) and pipe 80> FIG. 5 is a schematic cross-sectional view showing a joint structure between the core 60B (60) and the pipe 80 according to another embodiment of the present disclosure. The abovedescribed core 60B shown in this figure has an insulator 110 stacked in the first direction. As described above, the core 60B includes a steel sheet laminate 79 containing a plurality of steel sheets 77. Each steel sheet 77 has a steel sheet inner peripheral surface 176 that defines a steel sheet hole 78 penetrating in the first direction.

[0035] The pipe 80 is inserted into the insertion hole 68B (68) and the insulator hole 115. The pipe outer peripheral surface 89 of the pipe 80 illustrated in FIG. 5 has a portion that overlaps in the axial direction with the powder magnetic core inner peripheral surface 76, a portion that overlaps in the axial direction with the steel sheet inner peripheral surface 176, and a portion that overlaps in the axial direction with the insulator inner peripheral surface 116.

[0036] In this example, an insulating member 120 is further disposed at least between the pipe outer peripheral surface 89 and the steel sheet inner peripheral surface 176. The insulating member 120 illustrated in this figure is disposed between the pipe outer peripheral surface 89 and the steel sheet inner peripheral surface 176, between the pipe outer peripheral surface 89 and the powder magnetic core inner peripheral surface 76, and between the pipe outer peripheral surface 89 and the insulator inner peripheral surface 116. The insulating member 120 may be formed by insulating the pipe outer peripheral surface 89 with an insulating coating, or it may be a member formed of a resin material, ceramic material, or rubber material.

[0037] Generally, punching is performed on a steel sheet material (not shown) with an insulating coating on the outer surface to obtain the steel sheet 77 having the steel sheet inner peripheral surface 176. Therefore, no insulating coating is formed on the steel sheet inner peripheral surface 176. Hence, if an eddy current is generated in any of the plurality of laminated steel sheets 77, the current may flow to the other steel sheets 77 via the steel sheet inner peripheral surface 176. In other words, the current may flow through the steel sheet laminate 79 in the first direction. In this regard, with the above configuration, since the insulator 110 is disposed between the pipe outer peripheral surface 89 and the steel sheet inner peripheral surface 176, the current generated in any of the steel sheets 77 can be prevented from flowing through the steel sheet laminate 79 in the first direction. [003 8] <6. Slit 85 of pipe 80> FIGs. 6A to 6C are a schematic diagram of a pipe 81, 82, 83 (80) as an example of the pipe 80. The pipe 81 to 83 illustrated in FIGs. 6Ato 6C includes a peripheral wall 84A, 84B, 84C (84) and a slit 85A, 85B, 85C (85) penetrating the peripheral wall 84 in the radial direction of the pipe 80. The slit 85A, 85B, 85C extends along the first direction. More precisely, the slit 85A, 85B extends in a straight line along the first direction, and the slit 85C extends in a spiral along the first direction.

[0039] As illustrated in FIGs. 6A and 6C, the slit 85A, 85C (85) may be formed from one end to the other end of the pipe 81, 83 (80) in the first direction. In other words, the slit 85 A, 85C is open to one side and the other side in the first direction. Alternatively, as illustrated in FIG. 6B, the slit 85B (85) may be open to one side in the first direction, while the slit 85B may not be open to the other side. In this case, the other end of the slit 85B in the first direction is located on one side of the other end of the pipe 82 (80). Although not described in detail, both ends of the slit 85 in the first direction may not be open in the first direction. In other words, both ends of the slit 85 in the first direction may be located closer to the center of the pipe 80 in the first direction rather than both ends of the pipe 80 in the first direction. The number of slits 85 formed in the pipe 80 should be one, which simplifies the structure of the pipe 80.

[0040] With the above configuration, the slit 85 allows the pipe 80 to be inserted into the insertion hole 68 in the manufacturing process of the core unit 10 with the pipe 80 compressed toward the axis. After the completion of insertion, the compressed pipe 80 widens away from the axis, and at least a part of the peripheral wall 84 of the pipe 80 presses against the inner peripheral surface constituting the insertion hole 68 (more specifically, the powder magnetic core inner peripheral surface 76 as an example). This improves the thermal conductivity from the powder magnetic core 70 to the pipe 80 and further improves the cooling performance of the core unit 10.

[0041] <7. Example of rotor 30 that incorporates core unit 10> Referring to FIGs. 7 and 8, a rotor 30 that incorporates the core unit 10 will be described. The rotor 30 is configured to rotate in the circumferential direction perpendicular to the first direction and is connected to, for example, a rotational shaft 5 that constitutes a magnetic geared electrical machine 1 (see FIG. 9) (overview of the configuration of the magnetic geared electrical machine 1 will be described below). The first direction coincides with the axial direction of the rotor 30, and the rotational shaft 5 extends in the first direction. In the following description, the radial direction of the rotor 30 with respect to the axis may simply be referred to as the “radial direction”.

[0042] FIG. 7 is a schematic diagram of the rotor 30 according to an embodiment. The rotor 30 is provided with a ring unit 50 extending in the circumferential direction. The ring unit 50 includes a plurality of core units 10 and a plurality of non-magnetic bodies 52. The plurality of core units 10 and the plurality of non-magnetic bodies 52 are arranged alternately in the circumferential direction, and each core unit 10 is sandwiched by a pair of non-magnetic bodies 52 located on both sides in the circumferential direction. In the illustrated example, a pair of end rings 31, as components of the rotor 30, is disposed on both ends of the ring unit 50 in the first direction, respectively. The end ring 31 is a plate-like structure extending in the circumferential direction with thickness in the first direction.

[0043] The rotor 30 is further provided with a pair of flanges 41 respectively connected to both end portions of the ring unit 50 in the first direction, each flange 41 being configured to be connected to the rotational shaft 5. The following is a detailed example of the configuration of the flange 41. The flange 41 has a ring portion 42 extending in the circumferential direction, a plurality of extension portions 47 extending radially inward from the ring portion 42, and a shaft connection portion 48 connected to inner ends of the extension portions 47. The ring portion 42 in this example is a plate-like structure with thickness in the first direction and is connected to an end portion of the ring unit 50 via the end ring 31 (i .e., the flange 41 is indirectly connected to the end portion of the ring unit 50). The shaft connection portion 48 is cylindrical along the first direction, and the inner peripheral surface of the shaft connection portion 48 is connected to the rotational shaft 5 (see FIG. 9).

[0044] Furthermore, the ring portion 42 of the flange 41 has at least one flange hole 43 communicating in the first direction with the internal space of each pipe 80 (see FIGs. 2A and 2B) of the core unit 10. In the example of FIG. 7, the flange holes 43 face a plurality of end ring holes (not shown) formed in the end ring 31 in the first direction, and the plurality of end ring holes face the insulator holes 115 (see FIG. 1) in the plurality of core units 10 in the first direction, respectively. This allows the flange hole 43 to communicate with the internal space of the pipe 80 and allows air to flow through the internal space of the pipe 80 as the rotor 30 rotates.

[0045] To illustrate a more detailed configuration example, the at least one flange hole 43 is a plurality of flange holes 43 arranged at intervals in the circumferential direction, and the plurality of flange holes 43 face the plurality of end ring holes in the first direction, respectively. However, the present disclosure is not limited to this configuration. Instead of being a circumferentially extending plate-like ring, the ring portion 42 in another embodiment may be a circumferentially extending frame-like (in other words, hollow) ring. In this case, a single open hole formed inside the frame corresponds to the flange hole 43. Therefore, the number of flange holes 43 is one. The rotor 30 may not include the pair of end rings 31. In this case, the ring portion 42 may be directly connected to the end portion of the ring unit 50. If the end 87 of the pipe 80 is located on the other side in the first direction relative to the end 111 of the insulator 110 (see FIGs. 3 and 5), contact between the end 87 of the pipe 80 and the ring portion 42, which may be made of metal, is avoided, so that unintended conduction between the core 60 and the ring unit 50 is avoided.

[0046] FIG. 8 is a schematic diagram showing a partial configuration of the ring unit 50 according to an embodiment of the present disclosure. In this figure, the circumferential direction is shown as coinciding with the left-right direction of the paper. The non-magnetic body 52 is formed of a FRP as described above. The FRP may be, for example, a glass fiber-reinforced plastic (GFRP; Glass Fiber Reinforced Plastics) or a carbon fiber-reinforced plastic (CFRP; Carbon Fiber Reinforced Plastics).

[0047] In addition, the ring unit 50 includes a flexible member 150 interposed between the core 60 and the non-magnetic body 52. The flexible member 150 has a smaller Young's modulus than the core 60 and is elastically deformable in the first direction. The flexible member 150 is formed of, for example, rubber, resin, or elastomer. The flexible member 150 is preferably sheet-like. In the illustrated example, the flexible member 150 is interposed between the core 60 and the non-magnetic body 52 over the entire length of the core 60 in the first direction.

[0048] With the above configuration, since the non-magnetic body 52 is a fiber-reinforced composite material, the insulation of the non-magnetic body 52 is ensured, while the reduction in weight and the increase in rigidity of the rotor 30 are achieved. On the other hand, the coefficient of linear expansion of the non-magnetic body 52 formed of FRP is smaller than that of the powder magnetic core 70. Therefore, when the temperature of the rotor 30 having a configuration where the powder magnetic core 70 and the non-magnetic body 52 are in direct contact with each other rises, the non-magnetic body 52 is extended in the first direction more than the powder magnetic core 70. As a result, tensile stress caused by the expansion of the non-magnetic body 52 occurs in the powder magnetic core 70 as thermal stress, and the powder magnetic core 70, which has relatively weak mechanical strength, may be damaged. In other words, there is a possibility of a defect occurring in the powder magnetic core 70. In this regard, with the above configuration, the flexible member 150 has a portion that contacts the non-magnetic body 52 and a portion that contacts the core 60, and the amount of extension in the first direction of both portions can be different. That is, the flexible member 150 can reduce the thermal stress generated in the powder magnetic core 70. Thus, the rotor 30 can suppress the destruction of the powder magnetic core 70.

[0049] The flexible member 150 according to an embodiment is formed of a thermoplastic elastomer. With the above configuration, since the elastomer has an adhesive function, there is no need to prepare a single adhesive material to bond the core 60, the non-magnetic body 52, and the flexible member 150. This simplifies the configuration of the rotor 30.

[0050] In the example of FIG. 3, flexible members 151, 152 formed of the same material as the flexible member 150 are disposed on the radially outer and inner surfaces of the core unit 10, respectively. The flexible members 150 to 152 in this example are an integrally formed sheet material made of elastomer and are provided to enclose the core unit 10. Further, the rotor 30 in this figure also includes an outer cover 55A covering the ring unit 50 from the radially outer side, and an inner cover 55B covering the ring unit 50 from the radially inner side. The outer cover 55A and the inner cover 55B in this example are prepreg materials made of a fiber base material, such as CFRP, impregnated with thermosetting resin. The outer cover 55 A and the inner cover 55B are joined to the ring unit 50 by adhering to the flexible members 151, 152 via an adhesive layer 59. The outer cover 55 A and the inner cover 55B are provided along the entire circumferential length of the ring unit 50 to reinforce the ring unit 50.

[0051] <8. Example of rotor 30 that incorporates core unit 10> FIG. 9 is a schematic diagram showing a magnetic geared electrical machine 1 equipped with the rotor 30. The magnetic geared electrical machine 1 includes a rotational shaft 5 extending in the first direction, and the rotor 30 includes a pair of flanges 41 as described above. Each flange 41 is directly connected to the rotational shaft 5. The magnetic geared electrical machine 1 further includes a magnet rotor 15 supported via a bearing by the rotational shaft 5 between the pair of flanges 41. The magnet rotor 15 has a plurality of rotor magnets 19 arranged in the circumferential direction inside the core unit 10. The magnetic geared electrical machine 1 further includes a stator 20 fixed outside the core unit 10 in the radial direction. The stator 20 has a plurality of stator magnets 29 arranged in the circumferential direction, a stator yoke 25 supporting the plurality of stator magnets 29, and a coil 27 as an armature coil wound on the stator yoke 25. The coil 27 is electrically connected to an electric power system 6. In the magnetic geared electrical machine 1 having the above structure, the core unit 10 functions as a pole piece unit, and the rotor 30 functions as a pole piece rotor.

[0052] The rotational shaft 5 is connected to an external rotating device 7. The magnetic geared electrical machine lisa magnetic geared motor configured to drive the external rotating device upon receiving electric power supplied from the electric power system 6, for example. The operating principle of the magnetic geared electrical machine 1 as a magnetic geared motor is as follows. The magnet rotor 15 rotates by a rotating magnetic field generated by energization of the coil 27. The positional relationship of the plurality of core units 10 relative to the plurality of rotor magnets 19 and the plurality of stator magnets 29 changes, the magnetic flux between the magnet rotor 15 and the stator 20 is modulated, and the rotor 30 rotates together with the rotational shaft 5. Torque is transmitted from the rotational shaft 5 to the external rotating device 7, so that the external rotating device 7 can be driven.

[0053] The magnetic geared electrical machine 1 may be a magnetic geared generator instead of a magnetic geared motor. In this case, a configuration in which the external rotating device 7 drives the rotational shaft 5 is adopted. When the rotor 30 rotates together with the rotational shaft 5, the positional relationship of the plurality of core units 10 relative to the plurality of rotor magnets 19 and the plurality of stator magnets 29 changes, and the magnet rotor 15 rotates. The electromagnetic induction caused by the rotation of the rotor 30 and the magnet rotor 15 generates a current in the coil 27, so that electric power is supplied to the electric power system 6.

[0054] The rotor 30 equipped with the core unit 10 can improve the cooling performance for the reasons already described. In addition, at least one of centrifugal force, vibration, or electromagnetic force acts on the core unit 10 as the magnetic geared electrical machine 1 is operated, which may damage the powder magnetic core 70. Even in this case, for the reasons already described, the rotor 30 can prevent the powder magnetic core 70 from falling off the core unit 10.

[0055] <9. Others> The disclosure is not limited to the core unit 10 incorporated into the rotor 30. The core unit 10 may be incorporated into the stator 20 of the above-described magnetic geared electrical machine 1. Alternatively, the core unit 10 may be incorporated into a stator (not shown) that constitutes an axial gap motor.

[0056] <10. Conclusion> The contents described in some embodiments described above would be understood as follows, for instance.

[0057] 1) A core unit (10) according to at least one embodiment of the present disclosure is provided with: a core (60) including at least one powder magnetic core (70) having a powder magnetic core hole (75) penetrating in a first direction; and a pipe (80) extending in the first direction and inserted into the powder magnetic core hole.

[0058] With the above configuration 1), since the powder magnetic core hole is formed in the powder magnetic core for insertion of the pipe, air flowing through the internal space of the pipe can cool the core. This suppresses the temperature rise of the core caused by the generation of eddy current or the energization of an armature coil, for example. Further, the powder magnetic core may be damaged due to the generation of tensile stress in the first direction, for example. In this regard, with the above configuration 1), since the pipe is inserted into the powder magnetic core hole, a fragmented powder magnetic core is prevented from falling off the core even if the powder magnetic core is damaged. Thus, it is possible to achieve the core unit that can maintain the shape of the powder magnetic core and improve the cooling performance of the core.

[0059] 2) In some embodiments, in the core unit as defined in the above 1), the pipe includes: a peripheral wall (84); and a slit (85) penetrating the peripheral wall in a radial direction and extending along the first direction.

[0060] With the above configuration 2), the slit allows the pipe to be inserted into the insertion hole in the manufacturing process of the core unit with the pipe compressed toward the axis. After the completion of insertion, the compressed pipe widens away from the axis, and at least a part of the peripheral wall of the pipe presses against the powder magnetic core inner peripheral surface. This improves the thermal conductivity from the powder magnetic core to the pipe and further improves the cooling performance of the core unit.

[0061] 3) In some embodiments, in the core unit as defined in the above 1) or 2), the core unit is further provided with an adhesive (9) interposed between a pipe outer peripheral surface (89) of the pipe and a powder magnetic core inner peripheral surface (76) of the powder magnetic core defining the powder magnetic core hole.

[0062] With the above configuration 3), since the adhesive is interposed between the pipe outer peripheral surface and the powder magnetic core inner peripheral surface, the fragmented powder magnetic core caused by damage is prevented from falling off the core. Additionally, since the pipe outer peripheral surface and the powder magnetic core inner peripheral surface can adhere to each other via the adhesive, the thermal conductivity from the powder magnetic core to the pipe is further improved.

[0063] 4) In some embodiments, in the core unit as defined in the above 3), the pipe outer peripheral surface has at least one of an outer peripheral surface recess (181) or an outer peripheral surface protrusion (183).

[0064] With the above configuration 4), since the amount of the adhesive interposed between the pipe outer peripheral surface and the powder magnetic core inner peripheral surface increases, the fragmented powder magnetic core caused by damage is further prevented from falling off the core.

[0065] 5) In some embodiments, in the core unit as defined in any of the above 1) to 4), the core unit is further provided with an insulator (110) disposed so as to be stacked on an end portion of the core in the first direction, the insulator having an insulator hole (115) penetrating in the first direction. The pipe is inserted into the insulator hole.

[0066] With the above configuration 5), the pipe is inserted into the insulator hole of the insulator stacked on the end portion of the core, making it difficult for the pipe to be removed from the powder magnetic core hole. Thus, the mechanical strength of the core unit is improved. Further, the insulator suppresses a leakage magnetic flux that tends to occur in the end portion of the core in the first direction, thereby suppressing the generation of eddy current in the core. Accordingly, the temperature rise of the core can be suppressed.

[0067] 6) In some embodiments, in the core unit as defined in the above 5), one end (87) of the pipe on one side in the first direction is located on a side opposite the one side relative to an end (111) of the insulator on the one side.

[0068] With the above configuration 6), contact of one end of the pipe with a component (e.g., end ring 31) of another unit (e.g., rotor 30) into which the core unit is assembled is avoided. This prevents unintended conduction between the core and the component.

[0069] 7) In some embodiments, in the core unit as defined in any of the above 1) to 6), the core includes a plurality of the powder magnetic cores laminated in the first direction. The pipe is inserted into the powder magnetic core hole of each powder magnetic core.

[0070] With the above configuration 7), since the core includes a plurality of powder magnetic cores, it is possible to downsize each powder magnetic core forming the core. This simplifies the work of inserting each powder magnetic core into the pipe during the assembly process of the core. In addition, downsizing the powder magnetic core reduces the molding pressure required for a molding machine used in the molding process of the powder magnetic core, simplifying the production of the powder magnetic core.

[0071] 8) In some embodiments, in the core unit as defined in any of the above 1) to 7), the core further includes: a steel sheet laminate (79) having a plurality of steel sheets (77) laminated in the first direction; and a one-side powder magnetic core (71) that is the powder magnetic core disposed on one side in the first direction relative to the steel sheet laminate, the one-side powder magnetic core forming an end portion of the core on the one side.

[0072] With the above configuration 8), the one-side powder magnetic core, which forms an end portion of the core in the first direction, suppresses a leakage magnetic flux that tends to occur in the end portion of the core on one side, thereby suppressing the generation of eddy current in the core. Accordingly, the temperature rise of the core can be suppressed.

[0073] 9) In some embodiments, in the core unit as defined in any of the above 1) to 8), the pipe is longer than the core in the first direction and is inserted from one end portion to the other end portion of the core in the first direction.

[0074] With the above configuration 9), since the pipe is inserted to pass through the core, the pipe supports the core more firmly and improves the mechanical strength of the core unit.

[0075] 10) In some embodiments, in the core unit as defined in any of the above 1) to 9), the pipe is formed of a non-magnetic material.

[0076] With the above configuration 10), it is possible to suppress the hysteresis loss caused by magnetization of the pipe and maintain the magnetic flux modulating function of the core.

[0077] 11) In some embodiments, in the core unit as defined in the above 10), the pipe is formed of a non-magnetic metal material.

[0078] With the above configuration 11), the thermal conductivity of the pipe is improved, so that the thermal transfer from the powder magnetic core to the pipe is further improved.

[0079] 12) In some embodiments, in the core unit as defined in any of the above 1) to 11), the core includes a plurality of steel sheets (77) laminated in the first direction, each steel sheet having a steel sheet hole (78) penetrating in the first direction. The core unit is further provided with an insulating member (120) interposed between a pipe outer peripheral surface (89) of the pipe and a steel sheet inner peripheral surface (176) of the steel sheet defining the steel sheet hole.

[0080] Generally, no insulating coating is formed on the steel sheet inner peripheral surface. Hence, if an eddy current is generated in any of the steel sheets, the current may flow through the steel sheet laminate in the first direction via the steel sheet inner peripheral surface. In this regard, with the above configuration 12), since the insulating member is disposed between the pipe outer peripheral surface and the steel sheet inner peripheral surface, the current generated in any of the steel sheets can be prevented from flowing through the steel sheet laminate in the first direction.

[0081] 13) In some embodiments, in the core unit as defined in any of the above 1) to 12), the pipe further includes: a pipe inner peripheral surface (86); and at least one of an inner peripheral surface protrusion (861) or an inner peripheral surface recess (863) disposed on the pipe inner peripheral surface.

[0082] With the above configuration 13), heat exchange between the pipe inner peripheral surface and air is promoted, so that the cooling performance of the core is improved.

[0083] 14) A rotor (30) according to at least one embodiment of the present disclosure is provided with: a ring unit (50) including a plurality of the core units (10) as defined in any of the above 1) to 12), and a plurality of non-magnetic bodies (52) arranged alternately with the plurality of core units in a circumferential direction that is perpendicular to the first direction; and a pair of flanges (34) respectively connected to both end portions of the ring unit in the first direction, each flange being configured to be connected to a rotational shaft extending in the first direction. Each flange has at least one flange hole (43) communicating with an internal space of the pipe (80) of each of the plurality of core units.

[0084] With the above configuration 14), for the same reasons as described in 1), it is possible to achieve the rotor that can maintain the shape of the powder magnetic core and improve the cooling performance of the core.

[0085] 15) In some embodiments, in the rotor (30) as defined in the above 14), each non magnetic body is formed of a fiber-reinforced composite material. The ring unit further includes a flexible member (150) interposed between the core and the non-magnetic body.

[0086] With the above configuration 15), since the non-magnetic body is a fiber-reinforced composite material, the insulation of the non-magnetic body is ensured, while the reduction in weight and the increase in rigidity of the rotor are achieved. On the other hand, the coefficient of linear expansion of the non-magnetic body formed of a fiber-reinforced composite material is smaller than that of the powder magnetic core. Therefore, when the temperature of the rotor having a configuration where the powder magnetic core and the non-magnetic body are in direct contact with each other rises, the non-magnetic body is extended in the first direction more than the powder magnetic core. As a result, tensile stress caused by the expansion of the nonmagnetic body occurs in the powder magnetic core as thermal stress, and the powder magnetic core, which has relatively weak mechanical strength, may be damaged. In other words, there is a possibility of a defect occurring in the powder magnetic core. In this regard, with the above configuration 15), the flexible member has a portion that contacts the non-magnetic body and a portion that contacts the core, and the amount of extension in the first direction of both portions can be different. That is, the flexible member can reduce the thermal stress generated in the powder magnetic core. Thus, the rotor can suppress the destruction of the powder magnetic core.

[0087] 16) In some embodiments, in the rotor as defined in the above 15), the flexible member is formed of an elastomer.

[0088] With the above configuration 16), since the elastomer has an adhesive function, there is no need to prepare a single adhesive material to bond the core, the non-magnetic body, and the flexible member. This simplifies the configuration of the rotor. Reference Signs List

[0089] 5 Rotational shaft 9 Adhesive 10 Core unit 30 Rotor 41 Flange 43 Flange hole 50 Ring unit 52 Non-magnetic body 60 Core 70 Powder magnetic core 71 One-side powder magnetic core 75 Powder magnetic core hole 76 Powder magnetic core inner peripheral surface 77 Steel sheet 78 Steel sheet hole 79 Steel sheet laminate 80 (80A, 81 to 83) Pipe Peripheral wall Slit Pipe inner peripheral surface One end Pipe outer peripheral surface Insulator End Insulator hole Insulating member Flexible member Steel sheet inner peripheral surface Outer peripheral surface recess Outer peripheral surface protrusion Inner peripheral surface protrusion Inner peripheral surface recess

Claims

1. A core unit, comprising:a core including at least one powder magnetic core having a powder magnetic core hole penetrating in a first direction; anda pipe extending in the first direction and inserted into the powder magnetic core hole.

2. The core unit according to claim 1,wherein the pipe includes:a peripheral wall; anda slit penetrating the peripheral wall in a radial direction and extending along the first direction.

3. The core unit according to claim 1 or 2, further comprising an adhesive interposed between a pipe outer peripheral surface of the pipe and a powder magnetic core inner peripheral surface of the powder magnetic core defining the powder magnetic core hole.

4. The core unit according to claim 3,wherein the pipe outer peripheral surface has at least one of an outer peripheral surface recess or an outer peripheral surface protrusion.

5. The core unit according to claim 1 or 2, further comprising an insulator disposed so as to be stacked on an end portion of the core in the first direction, the insulator having an insulator hole penetrating in the first direction,wherein the pipe is inserted into the insulator hole.

6. The core unit according to claim 5,wherein one end of the pipe on one side in the first direction is located on a side oppositethe one side relative to an end of the insulator on the one side.

7. The core unit according to claim 1 or 2,wherein the core includes a plurality of the powder magnetic cores laminated in the first direction, andwherein the pipe is inserted into the powder magnetic core hole of each powder magneticcore.

8. The core unit according to claim 1 or 2,wherein the core further includes:a steel sheet laminate having a plurality of steel sheets laminated in the first direction; anda one-side powder magnetic core that is the powder magnetic core disposed on one side in the first direction relative to the steel sheet laminate, the one-side powder magnetic core forming an end portion of the core on the one side.

9. The core unit according to claim 1 or 2,wherein the pipe is longer than the core in the first direction and is inserted from one end portion to the other end portion of the core in the first direction.

10. The core unit according to claim 1 or 2,wherein the pipe is formed of a non-magnetic material.

11. The core unit according to claim 10,wherein the pipe is formed of a non-magnetic metal material.

12. The core unit according to claim 1 or 2,wherein the core includes a plurality of steel sheets laminated in the first direction, eachsteel sheet having a steel sheet hole penetrating in the first direction, andwherein the core unit further comprises an insulating member interposed between a pipe outer peripheral surface of the pipe and a steel sheet inner peripheral surface of the steel sheet defining the steel sheet hole.

13. The core unit according to claim 1 or 2,wherein the pipe further includes:a pipe inner peripheral surface; andat least one of an inner peripheral surface protrusion or an inner peripheral surface recess disposed on the pipe inner peripheral surface.

14. A rotor, comprising:a ring unit including a plurality of the core units according to claim 1 or 2, and a plurality of non-magnetic bodies arranged alternately with the plurality of core units in a circumferential direction that is perpendicular to the first direction; anda pair of flanges respectively connected to both end portions of the ring unit in the first direction, each flange being configured to be connected to a rotational shaft extending in the first direction,wherein each flange has at least one flange hole communicating with an internal space of the pipe of each of the plurality of core units.

15. The rotor according to claim 14,wherein each non-magnetic body is formed of a fiber-reinforced composite material, andwherein the ring unit further includes a flexible member interposed between the core and the non-magnetic body.

16. The rotor according to claim 15,wherein the flexible member is formed of an elastomer.

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