Stator, magnetic gear electric machine, and method for assembling stator

Abstract

A stator core of this stator includes: a core inner peripheral surface that is an inner peripheral surface on which a plurality of magnets are arranged; a first protrusion that protrudes from the core inner peripheral surface to the radial inside and has a first support surface that supports a first inclined surface; and a second protrusion that protrudes from the core inner peripheral surface to the radial inside and has a second support surface that supports a second inclined surface. Both the first support surface and the second support surface are inclined with respect to the radial direction and are inclined toward the center side of a first radial magnet toward the inside in the radial direction.

Description

Stator, magnetic gear electric machine, and method for assembling the stator

[0001] This application claims priority to Japanese Patent Application No. 2023-122927, filed on July 28, 2023, with the Japan Patent Office, the contents of which are incorporated herein by reference.

[0002] The stator disclosed in Patent Document 1 is incorporated into a magnetic gear device and includes a stator core and a plurality of magnets arranged in a circumferential direction radially inward of the stator core.

[0003] US Patent Application Publication No. 2019 / 0157962

[0004] The inventors of the present application have devised a stator magnet arrangement using a Halbach array, which concentrates magnetic flux radially inward from the stator. However, because the magnetization directions of adjacent magnets in the circumferential direction are different, there is a concern that the magnets may become dislodged from the multiple teeth of the stator core. According to the inventors' findings, magnets magnetized radially outward are biased radially inward by magnetic forces from other magnets, which creates a particular concern that the magnets may become dislodged. Furthermore, it is preferable to prevent such magnet dislodgment with a simple configuration.

[0005] An object of the present disclosure is to provide a stator, a magnetic gear electric machine, and a method for assembling a stator that can suppress the falling-off of at least one of a plurality of magnets with a simple configuration.

[0006] a first inclined surface connected to one end of the outer circumferential surface in the circumferential direction and inclined toward the center of the circumferential direction of the first radial magnet as it moves toward the inside in the radial direction; and a second inclined surface connected to the other end of the outer circumferential surface in the circumferential direction and inclined toward the center of the first radial magnet as it moves toward the inside in the radial direction; and the stator core includes: a core inner circumferential surface which is an inner circumferential surface on which the plurality of magnets are arranged; a first protrusion protruding radially inward from the core inner circumferential surface and having a first support surface which supports the first inclined surface. a second protrusion protruding radially inward from the inner peripheral surface of the core and having a second support surface that supports the second inclined surface, wherein both the first support surface and the second support surface are inclined relative to the radial direction and are inclined toward the center of the first radial magnet as they move radially inward.

[0007] A magnetic gear electric machine according to at least one embodiment of the present disclosure includes the above-described stator; a pole piece rotor including a plurality of pole pieces arranged in the circumferential direction and radially inward of the stator; and a magnet rotor including an inner magnet arranged radially inward of the plurality of pole pieces.

[0008] A method for assembling a stator according to one embodiment of the present disclosure is the above-mentioned method for assembling a stator, comprising the steps of sliding the first radial magnet in the axial direction to engage the first inclined surface with the first protrusion and to engage the second inclined surface with the second protrusion.

[0009] According to the present disclosure, it is possible to provide a stator, a magnetic gear electric machine, and a method for assembling a stator that can suppress the falling off of at least one of a plurality of magnets with a simple configuration.

[0010] FIG. 1 is a schematic diagram of a magnetic gear electric machine according to an embodiment. FIG. 2 is a schematic diagram of a stator according to an embodiment. FIG. 3 is a partial enlarged view of FIG. 1. FIG. 4 is a schematic diagram of a stator core according to a first embodiment. FIG. 5 is a schematic diagram of a stator core according to a second embodiment. FIG. 6 is a schematic diagram showing an assembly process of a first radial magnet according to a second embodiment. FIG. 7 is a schematic diagram showing an assembly process of a first radial magnet following FIG. 7. FIG. 8 is a schematic diagram showing a detailed example of a first divided magnet and a second divided magnet. FIG. 9 is a schematic diagram of a stator core according to a third embodiment. FIG. 10 is a schematic diagram of a first radial magnet according to a third embodiment. FIG. 11 is a schematic diagram showing an assembly process of a first radial magnet according to a third embodiment. FIG. 12 is a schematic diagram of a plate according to a first example. FIG. 13 is a schematic diagram of a plate according to a second example. FIG. 14 is a schematic diagram of a plate according to a third example. FIG. 15 is a flowchart of a method of assembling a stator according to an embodiment. FIG. 16 is a schematic diagram showing the steps of a radial magnet arrangement step according to an embodiment. FIG. 17 is a schematic diagram of a stator according to another embodiment.

[0011] Several embodiments of the present disclosure will be described below with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are not intended to limit the scope of the present disclosure and are merely illustrative examples. For example, expressions expressing relative or absolute arrangements, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such arrangements, but also express relative displacements with a tolerance or angle or distance to the extent that the same function is achieved. For example, expressions expressing the equality of things, such as "same," "equal," and "homogeneous," not only express strict equality, but also express tolerance or differences to the extent that the same function is achieved. For example, expressions expressing shapes such as a square or cylindrical shape not only express shapes such as a square or cylindrical shape in the strict geometric sense, but also express shapes including concave and convex portions, chamfered portions, etc., to the extent that the same effect is achieved. On the other hand, the expressions "comprise," "include," or "have" one component are not exclusive expressions that exclude the existence of other components. Note that similar components may be assigned the same reference numerals and descriptions thereof may be omitted.

[0012] <Overall Configuration of Magnetic Gear Electric Machine 10> Figure 1 is a schematic diagram of a magnetic gear electric machine 10 according to an embodiment of the present disclosure. The magnetic gear electric machine 10 includes a rotating shaft 18 connected to an external device 9. In the following description, "axial direction" refers to the axial direction of the axis S of the rotating shaft 18, "circumferential direction" refers to the circumferential direction based on the axis S, and "radial direction" refers to the radial direction based on the axis S. "Radially inner" refers to the side approaching the axis S, and "radially outer" refers to the side moving away from the axis S. The axis S is also the axis of a stator (stator 20) for the magnetic gear electric machine 10, which will be described later.

[0013] The magnetic gear electric machine 10 includes a housing 17 that rotatably supports a rotating shaft 18 , and a stator 20 that is fixed to the housing 17 .

[0014] The stator 20 includes a stator core 24, which includes a yoke 29 extending in the circumferential direction and a plurality of teeth 25 protruding radially inward from the yoke 29. The teeth 25 are spaced apart in the circumferential direction. The stator 20 further includes a plurality of magnets 5 arranged in the circumferential direction on the inner side of the stator core 24, and a stator coil 27 wound around the teeth 25. The stator coil 27 is electrically connected to the power grid 16. In this example, a surface permanent magnet (SPM) type configuration is employed in which the magnets 5 are arranged on the inner circumferential surface of the stator core 24. The SPM type configuration of the stator 20 may be the configuration shown in FIG. 1 in which the magnets 5 are directly attached to the inner circumferential surfaces 259 of the teeth 25.

[0015] The magnetic gear electric machine 10 shown in FIG. 1 further includes a pole piece rotor 30. The pole piece rotor 30 includes an annular body 35 extending along the axis S radially inward of the stator 20, a connecting member 31 connecting one end of the annular body 35 to the rotating shaft 18, and a connecting member 32 connecting the other end of the annular body 35 to the rotating shaft 18. The annular body 35 includes multiple pole pieces 36 and multiple non-magnetic bodies (not shown) arranged alternately along the circumferential direction. The annular body 35 radially faces the stator 20 across an outer air gap G1. For example, if the inner circumferential surface 15 of each of the multiple magnets 5 is exposed to the outer air gap G1, the annular body 35 faces the multiple magnets 5. Alternatively, if another member such as a plate 70 (see FIGS. 13A to 13C) is attached to the inner circumferential surface 15, the annular body 35 faces the other member.

[0016] The connecting members 31, 32 extend radially. The connecting members 31, 32 illustrated in FIG. 1 are fixed to the rotating shaft 18, and the pole piece rotor 30 is configured to rotate integrally with the rotating shaft 18. The pole pieces 36 may be multiple electromagnetic steel sheets stacked in the axial direction, or at least one powder magnetic core extending in the axial direction, or a combination of these. If multiple electromagnetic steel sheets are stacked, the pole pieces 36 can suppress eddy current loss during generation.

[0017] The magnetic gear electric machine 10 further includes a magnet rotor 40 connected to the rotating shaft 18 between the connecting members 31 and 32. The magnet rotor 40 includes a plurality of inner magnets 41 arranged in the circumferential direction radially inside the annular body 35, and a rotor core 42 supporting the inner magnets 41. The rotor core 42 is connected to the rotating shaft 18 via a bearing, and the magnet rotor 40 is configured to rotate relative to the rotating shaft 18. The magnet rotor 40 faces the annular body 35 in the radial direction, with an inner air gap G2 between them. In the example of FIG. 1 , an SPM type configuration is used in which the plurality of inner magnets 41 are arranged on the outer circumferential surface of the rotor core 42. However, an interior permanent magnet (IPM) type configuration in which the plurality of inner magnets 41 are arranged inside the rotor core 42 may also be used.

[0018] The magnetic gear electric machine 10 according to one embodiment is a magnetic gear motor that receives power from a power grid 16 to drive an external device 9, and its operating principle is as follows: A rotating magnetic field generated by energizing the stator coil 27 causes the magnet rotor 40 to rotate. The relative position of the annular body 35 to the multiple inner magnets 41 and the multiple magnets 5 changes in the circumferential direction, and the magnetic flux between the magnet rotor 40 and the stator 20 is modulated by the multiple pole pieces 36, causing the pole piece rotor 30 to rotate. Torque is transmitted from the rotating shaft 18, which rotates together with the pole piece rotor 30, to the external device 9, thereby driving the external device 9.

[0019] The magnetic gear electric machine 10 according to another embodiment is a magnetic gear generator that receives power from an external device 9 and supplies electricity to a power grid 16. The operating principle is as follows: When the external device 9 drives the rotating shaft 18, the pole piece rotor 30 rotates together with the rotating shaft 18. The relative position of the annular body 35 to the multiple inner magnets 41 and the multiple magnets 5 changes in the circumferential direction, causing the magnet rotor 40 to rotate. Electromagnetic induction occurs as the pole piece rotor 30 and the magnet rotor 40 rotate, generating a current in the stator coil 27, which supplies electricity to the power grid 16.

[0020] If the number of magnetic poles in the pole piece 36 is NL, the number of magnetic pole pairs in the inner magnet 41 is NH, and the number of magnetic pole pairs in the magnet 5 is NS, then NL = NH + NS holds. When this relation holds, the ratio of the rotation speed of the magnet rotor 40 to the pole piece rotor 30 is expressed as NL / NH. In this example, NL / NH is greater than 1, so the magnet rotor 40 functions as a high-speed rotor, and the pole piece rotor 30 functions as a low-speed rotor. The number of magnetic poles NL in the pole piece 36 is less than the number of pole pairs NS in the magnet 5.

[0021] The magnetic gear electric machine 10 of the present disclosure is not limited to the above embodiment. The external device 9 may be connected to a power transmission shaft (not shown) arranged coaxially with the rotating shaft 18. The power transmission shaft and the rotating shaft 18 are not connected to each other. In this case, the connecting member 31 is connected to the rotating shaft 18 via a bearing, and the connecting member 32 is fixed to the power transmission shaft. Furthermore, the rotor core 42 of the magnet rotor 40 is fixed to the rotating shaft 18. Therefore, the magnet rotor 40 rotates integrally with the rotating shaft 18, and the pole piece rotor 30 rotates relative to the rotating shaft 18.

[0022] <Basic Configuration of Stator 20> Figure 2 is a schematic diagram of the stator 20 according to one embodiment of the present disclosure. Each of the multiple teeth 25 constituting the stator core 24 includes a protruding portion 251 that protrudes radially inward from the yoke 29 and a tip portion 252 that is connected to the tip of the protruding portion 251. The yoke 29, the protruding portion 251, and the tip portion 252 are integrally formed from the same soft magnetic material. The protruding portion 251 is shorter than the tip portion 252 in the circumferential direction. The stator coil 27 is provided so as to be wound around the protruding portion 251.

[0023] A slot opening 201 is formed as a space between two circumferentially adjacent tip portions 252, and a holding member 209, which may be made of, for example, a resin material, is disposed in the slot opening 201. The holding member 209 is held by the circumferential edges of each of the two tip portions 252.

[0024] The multiple magnets 5 are arranged on the inner circumferential side of the stator core 24. In the following description, the inner circumferential surface of the stator core 24 on which the multiple magnets 5 are arranged may be referred to as the "core inner circumferential surface 26." In the example of FIG. 2 , the tooth inner circumferential surface 259 and the inner circumferential surface of the retaining member 209 correspond to the core inner circumferential surface 26A (26) according to one embodiment. However, the present disclosure is not limited thereto. If another member is interposed between the tip portion 252, the retaining member 209, and the multiple magnets 5, the inner circumferential surface of the other member corresponds to the core inner circumferential surface 26B (26) according to another embodiment (see FIG. 17 ). Details of the core inner circumferential surface 26B will be described later.

[0025] The magnets 5 will be further described with reference to FIG. 2 . The multiple magnets 5 include a magnet group (for example, four magnets 5 arranged continuously in the circumferential direction) arranged in a Halbach array. This Halbach array strengthens the magnetic flux caused by the magnets 5 radially inward relative to the multiple magnets 5 relative to the radially outward. The stator 20 of this embodiment employs a configuration in which multiple magnet groups, each consisting of four magnets 5, are arranged. In other words, the total number of magnets 5 constituting the stator 20 is a multiple of four. In FIG. 2 , the four magnets 5 included in one magnet group are surrounded by a two-dot chain line J. Note that each magnet 5 extending in the axial direction is composed of multiple permanent magnets 12 stacked in the axial direction (see FIG. 16 ). In this specification, for convenience of explanation, each magnet 5 extending in the axial direction (see FIG. 2 ) is counted as one magnet. Note that the multiple permanent magnets 12 do not necessarily have the same shape. Details will be described later.

[0026] Hereinafter, the group of magnets arranged in the Halbach array may be referred to as "four magnets 5."

[0027] The four magnets 5 in the Halbach array include a first radial magnet 1 magnetized radially outward, a first circumferential magnet 3 magnetized on one circumferential side, a second circumferential magnet 4 magnetized on the other circumferential side, and a second radial magnet 2 magnetized radially inward. The first circumferential magnet 3 is located on one circumferential side of the first radial magnet 1, the second circumferential magnet 4 is located on the other circumferential side of the first radial magnet 1, and the second radial magnet 2 is located on the other circumferential side of the second circumferential magnet 4. The magnetization direction of these four magnets 5 is indicated by a thick arrow on each magnet 5, and the end of each magnet 5 facing the arrow is the north pole. In this example, the magnetization direction components of the first radial magnet 1 and the second radial magnet 2 include only radial components and no circumferential components. Furthermore, the magnetization direction components of the first circumferential magnet 3 and the second circumferential magnet 4 include only circumferential components and no radial components. However, the present disclosure is not limited to this, and each magnetization direction component of the first circumferential magnet 3 and the second circumferential magnet 4 may include a radial component in addition to a circumferential component (details will be described later).

[0028] Figure 3 is a partially enlarged view of Figure 2. Arrows A1 to A4 indicate the magnetic force that each magnet 5 receives due to the magnetic flux of the other magnets 5. More specifically, arrow A1 indicates the magnitude and direction of the magnetic force that the first radial magnet 1 receives. Similarly, arrow A2 indicates the direction and magnitude of the magnetic force that the second radial magnet 2 receives, arrow A3 indicates the direction and magnitude of the magnetic force that the first circumferential magnet 3 receives, and arrow A4 indicates the direction and magnitude of the magnetic force that the second circumferential magnet 4 receives. The length of arrows A1 to A4 indicates the magnitude of the magnetic force; the longer the arrow, the stronger the magnetic force. The direction and magnitude of these magnetic forces can be determined by simulation.

[0029] As can be seen from Figure 3, the first radial magnet 1 is subjected to the largest magnetic force directed radially inward, meaning that the risk of the first radial magnet 1 falling off is higher than the risk of the remaining three magnets 5 falling off. Furthermore, the second radial magnet 2 is also subjected to a magnetic force directed radially inward, meaning that the risk of the second radial magnet 2 falling off is higher than the risk of the first circumferential magnet 3 and the second circumferential magnet 4 falling off. Therefore, in this example, protrusions 50 for supporting the first radial magnet 1 and the second radial magnet 2 are provided on the core inner circumferential surface 26A (26). Note that, because a magnetic force directed radially outward acts on the first circumferential magnet 3 and the second circumferential magnet 4, a configuration for supporting these two magnets 5 is not essential.

[0030] The protrusions 50 include a first protrusion 51 and a second protrusion 52 that support the first radial magnet 1, and a third protrusion 53 and a fourth protrusion 54 that support the second radial magnet 2. The first protrusion 51 and the second protrusion 52 each support both end faces in the circumferential direction of the first radial magnet 1, and the third protrusion 53 and the fourth protrusion 54 each support both end faces in the circumferential direction of the second radial magnet 2. In this example, the first protrusion 51, the second protrusion 52, the third protrusion 53, and the fourth protrusion 54 are aligned in order from one side to the other in the circumferential direction.

[0031] The first radial magnet 1 and the second radial magnet 2 have the same shape. Furthermore, the first protrusion 51 and the third protrusion 53 have the same shape, and the second protrusion 52 and the fourth protrusion 54 have the same shape. To avoid repetition, the following will mainly describe the structure in which the first radial magnet 1 is supported by the first protrusion 51 and the second protrusion 52. All optional components related to the support structure for the first radial magnet 1 described below can also be applied to the support structure for the second radial magnet 2.

[0032] <Overview of Support Structure of First Radial Magnet 1> Prior to describing the support structure of the first radial magnet 1, an overview of the shape of the first radial magnet 1 will be described with reference to FIG. 4. FIG. 4 is a partially enlarged view of FIG. 3. The first radial magnet 1 has an outer peripheral surface 65 abutting against the tooth inner peripheral surface 259, a first inclined surface 61 connecting to one circumferential end 65a of the outer peripheral surface 65, and a second inclined surface 62 connecting to the other circumferential end 65b of the outer peripheral surface 65. The first inclined surface 61 and the second inclined surface 62 are inclined toward the circumferential center (imaginary line K1) of the first radial magnet 1 as they move radially inward. In this example, both the first inclined surface 61 and the second inclined surface 62 are inclined relative to the radial direction. The first inclined surface 61 may be directly connected to the one end 65a, or may be indirectly connected via another surface, such as a curved surface. Similarly, the second inclined surface 62 may be directly connected to the other end 65b, or may be indirectly connected.

[0033] In this example, the radial length (dimension M1) of the first inclined surface 61 is 50% or less, more specifically 25% or less, of the radial length of the first radial magnet 1. Similarly, the radial length of the second inclined surface 62 is 50% or less, more specifically 25% or less, of the radial length of the first radial magnet 1. Although not a required component of the present disclosure, the first radial magnet 1 has a circumferentially symmetrical shape, and the first inclined surface 61 and the second inclined surface 62 have the same radial length.

[0034] The first radial magnet 1 of this example further has an inner circumferential surface 66 (15) facing radially inward, a first connecting surface 63 connecting to the first inclined surface 61 and the inner circumferential surface 66, and a second connecting surface 64 connecting to the second inclined surface 62 and the inner circumferential surface 66. The first connecting surface 63 is directly connected to the radially inner end of the first inclined surface 61, and the second connecting surface 64 is directly connected to the radially inner end of the second inclined surface 62. Although not essential components of the present disclosure, the first connecting surface 63 and the second connecting surface 64 are flat surfaces extending parallel to the radial direction.

[0035] The first protrusion 51 and the second protrusion 52 will now be described. Both the first protrusion 51 and the second protrusion 52 protrude radially inward from the core inner circumferential surface 26. As a more specific example, the first protrusion 51 and the second protrusion 52 protrude radially inward from the tooth inner circumferential surface 259. In this example, the first protrusion 51, the second protrusion 52, and the tooth 25 are integrally formed from the same material. The radial length (dimension N1) of the first protrusion 51 is 25% or less of the radial length of the first radial magnet 1, more specifically, 10% or less. The radial length of the first protrusion 51 may also be shorter than the radial length of the first inclined surface 61. Similarly, the radial length of the second protrusion 52 is 25% or less of the radial length of the first radial magnet 1, more specifically, 10% or less. The radial length of the second protrusion 52 may also be shorter than the radial length of the second inclined surface 62. In this example, the first protrusion 51 and the second protrusion 52 are symmetrical to each other in the circumferential direction.

[0036] In this example, a plurality of first protrusions 51 and a plurality of second protrusions 52 are provided over the entire circumferential length of the stator core 24. At least one of the plurality of first protrusions 51 and the plurality of second protrusions 52 may protrude radially inward from the aforementioned holding member 209 (see FIG. 2). In this case, the protrusion 51 and the holding member 209 are integrally formed from the same material.

[0037] Referring to FIG. 4 , the description of the first protrusion 51 and the second protrusion 52 continues. The first protrusion 51 has a first support surface 55 that supports the first inclined surface 61, and the second protrusion 52 has a second support surface 56 that supports the second inclined surface 62. Both the first support surface 55 and the second support surface 56 are inclined radially and inclined toward the center of the first radial magnet 1 in the circumferential direction as they move radially inward. The first support surface 55 may directly abut the first inclined surface 61 or may indirectly abut the first inclined surface 61 via a separate member such as an adhesive. Similarly, the second support surface 56 may directly abut the second inclined surface 62 or may indirectly abut the second inclined surface 62. In the illustrated example, the first inclined surface 61 and the second inclined surface 62 are parallel to the first support surface 55 and the second support surface 56, respectively, but the present disclosure is not limited thereto. For example, when another member is interposed between the first inclined surface 61 and the first support surface 55, the first inclined surface 61 may be non-parallel to the first support surface 55. Similarly, the second inclined surface 62 may be non-parallel to the second support surface 56.

[0038] According to the above configuration, because the first support surface 55 and the second support surface 56 are inclined relative to the radial direction, the radially outward forces F1 and F2 acting on the first radial magnet 1 from the first support surface 55 and the second support surface 56 can be increased, preventing the first radial magnet 1 from falling off. Furthermore, because the force acting on the first radial magnet 1 can be increased without increasing the radial length of each of the first support surface 55 and the second support surface 56, the radial length of each of the first protrusions 51 and the second protrusions 52 can be shortened, simplifying the configuration of the stator core 24. As described above, a stator 20 is realized that can prevent at least one of the multiple magnets 5 from falling off with a simple configuration. The stator core 24 does not necessarily have to include the third protrusions 53 and the fourth protrusions 54. As described above, the risk of the second radial magnets 2 falling off is smaller than the risk of the first radial magnets 1 falling off, and a configuration may be employed in which the second radial magnets 2 are attached to the tooth inner circumferential surfaces 259 with, for example, an adhesive. Even in such an embodiment, the above-mentioned advantages can be obtained.

[0039] Furthermore, by configuring the core inner surface 26A (26) to include the tooth inner surface 259, the first protrusion 51 and the second protrusion 52 can be integrated with multiple teeth 25, thereby further simplifying the configuration of the stator 20.

[0040] Further details of the first protrusion 51 and the second protrusion 52 will be described below in the order of a first embodiment, a second embodiment, and a third embodiment. However, the present disclosure is not limited to these three embodiments. In the following description, one side in the axial direction may be simply referred to as the "first side," and the other side in the axial direction may be simply referred to as the "second side."

[0041] <Details of the First Protrusion 51 and the Second Protrusion 52 (First Embodiment)> Figure 5 is a schematic diagram of the stator 20A (20) according to the first embodiment. The stator 20A includes a stator core 24A (24). The first protrusion 51A (51) and the second protrusion 52A (52) of the stator core 24A are both provided on a tooth inner peripheral surface 259, which is an example of a core inner peripheral surface 26. In the example shown in the figure, at least one of the first protrusion 51A and the second protrusion 52A extends continuously in the axial direction over the entire axial length of the tooth inner peripheral surface 259. In the illustrated example, both the first protrusion 51A and the second protrusion 52A extend continuously in the axial direction and support the first radial magnet 1A (1).

[0042] 5 is configured from a single member extending in the axial direction, the present disclosure is not limited to this. For example, the first radial magnet 1A may be configured from a plurality of permanent magnets 12 (see FIG. 16), or as a more detailed example, a plurality of first divided magnets 111 and second divided magnets 222 (see FIG. 6).

[0043] An example of a method for assembling the first radial magnet 1A is shown below. The first radial magnet 1A is placed on the second axial side of the stator core 24. The first radial magnet 1A is slid axially toward the first side (arrow B1 in FIG. 5 ) so that the first inclined surface 61 engages with the first support surface 55 and the second inclined surface 62 engages with the second support surface 56. This assembles the first radial magnet 1A to the first protrusions 51A and the second protrusions 52A. By repeatedly performing this assembly process, multiple first radial magnets 1A are assembled to the stator core 24A around the circumference.

[0044] In another example of an assembly method for the first radial magnet 1A, the first support surface 55 of the first protrusion 51A and the second support surface 56 of the second protrusion 52A may both be parallel to the radial direction before the first radial magnet 1A is placed. As a more specific example, the protruding directions of the first protrusion 51A and the second protrusion 52A may both be parallel to the radial direction before the first radial magnet 1A is placed. In this case, the first radial magnet 1A may be placed between the first protrusion 51A and the second protrusion 52A, and then the first protrusion 51A and the second protrusion 52A may be deformed toward the first radial magnet 1A. As a result of this deformation, the first support surface 55 engages with the first inclined surface 61, and the second support surface 56 engages with the second inclined surface 62.

[0045] According to the above configuration, the axial range in which the first radial magnet 1A is supported by at least one of the first protrusions 51A and the second protrusions 52A can be expanded, thereby further preventing the first radial magnet 1A from falling off.

[0046] <Details of the First Protrusions 51 and the Second Protrusions 52 (Second Embodiment)> FIG. 6 is a schematic diagram of a stator 20B (20) according to a second embodiment. The stator 20B includes a stator core 24B (24). The stator core 24B includes a plurality of first protrusions 51B (51) spaced apart in the axial direction and a plurality of second protrusions 52B (52) spaced apart in the axial direction. The axial lengths of the first protrusions 51B and the second protrusions 52B are the same. The axial range in which the plurality of first protrusions 51B are arranged is the same as the axial range in which the plurality of second protrusions 52B are arranged. For example, the stator core 24 may be configured with multiple types of laminated steel plates stacked together. The multiple types of laminated steel plates include first laminated steel plates for forming the first protrusions 51B and the second protrusions 52B and second laminated steel plates that do not form the first protrusions 51B and the second protrusions 52B.

[0047] Furthermore, the first radial magnet 1B (1) supported by the first protrusions 51B and the second protrusions 52B includes a first divided magnet 111B (111) and a second divided magnet 222B (222) arranged so as to be stacked in the axial direction. In this example, a plurality of first divided magnets 111B and a plurality of second divided magnets 222B are arranged so as to be alternately stacked in the axial direction. The first divided magnet 111B engages with the first protrusions 51B and the second protrusions 52B. On the other hand, the second divided magnet 222C is arranged so as to be offset in the axial direction from the first protrusions 51B and the second protrusions 52B. Note that both the first divided magnet 111B and the second divided magnet 222B are examples of stacked permanent magnets 12 (see FIG. 16 ) that constitute the magnet 5.

[0048] 6, the first divided magnet 111B has a first inclined surface 61, a second inclined surface 62, a first connecting surface 63, and a second connecting surface 64. These surfaces have been described above. The number of first divided magnets 111 is the same as the number of first protrusions 51B (i.e., the number of second protrusions 52B), and the axial length of each first divided magnet 111 is the same as the axial length of each first protrusion 51B and the axial length of each second protrusion 52B.

[0049] The second divided magnet 222B does not have the first inclined surface 61, the second inclined surface 62, the first connecting surface 63, or the second connecting surface 64. As an example, one circumferential end face of the second divided magnet 222B, which may have a substantially rectangular parallelepiped shape, is flush with the first connecting surface 63 of the first divided magnet 111B. The other circumferential end face of the second divided magnet 222B is flush with the second connecting surface 64 of the first divided magnet 111B. Therefore, the second divided magnet 222B is disposed circumferentially between the tip 511 of the first protrusion 51B and the tip 522 of the second protrusion 52B. In other words, the second divided magnet 222 is disposed between the tips 511 and 522 when viewed in the axial direction.

[0050] Each first divided magnet 111B has a first magnet end face 115, which is the end face on the first side, and each second divided magnet 222B has a second magnet end face 125, which is the end face on the second side. The first magnet end face 115 and the second magnet end face 125 are abutted via adhesive. Therefore, even if only the first divided magnet 111B of the first divided magnet 111B or the second divided magnet 222B is supported by the first protrusions 51B and the second protrusions 52B, the first radial magnet 1B is prevented from falling off.

[0051] Referring to Figures 6 to 8, an example of an assembly method for the first radial magnet 1B according to the second embodiment is shown. Figures 7 and 8 are schematic diagrams showing the assembly process for the first radial magnet 1B. As shown in Figure 7, the first radial magnet 1B is positioned radially inward of the first protrusions 51B and second protrusions 52B. At this time, the first divided magnet 111B is shifted axially from the first protrusions 51B and second protrusions 52B.

[0052] Next, the first radial magnet 1B is moved radially outward (arrow D1 in FIG. 7 ) until it abuts against the tooth inner circumferential surface 259 (see FIG. 8 ). At this time, the first divided magnet 111B is offset axially from the first protrusions 51B and second protrusions 52B, so interference between the first divided magnet 111B and the first protrusions 51B and second protrusions 52B can be avoided. Furthermore, the second divided magnet 222 is positioned circumferentially between the protrusions 511 and 522, so interference between the second divided magnet 222B and the first protrusions 51B and second protrusions 52B can also be avoided.

[0053] Thereafter, the first radial magnet 1B is slid in the axial direction (arrow D2 in FIG. 8 ) to engage the first divided magnet 111B with the first protrusions 51B and the second protrusions 52B (see FIG. 6 ). This assembles the first radial magnet 1B to the first protrusions 51B and the second protrusions 52B. By repeating this assembly process, multiple first radial magnets 1B are assembled to the stator core 24B around the circumferential direction.

[0054] According to the above configuration, the first radial magnet 1B is divided into first divided magnets 111B and second divided magnets 222B as the multiple permanent magnets 12, thereby reducing eddy current loss generated in the first radial magnet 1B. Furthermore, the axial length of each of the first protrusions 51B and second protrusions 52B can be made shorter than the axial length of the teeth 25, further simplifying the configuration of the stator core 24B. Furthermore, in the assembly process of the first radial magnet 1B, the first radial magnet 1B can be moved from the radial inside to the radial outside (arrow D1 in FIG. 7 ) with the first divided magnet 111B axially offset from the first protrusions 51B and second protrusions 52B, thereby bringing the first radial magnet 1B into contact with the tooth inner circumferential surface 259, which is an example of the core inner circumferential surface 26A. Then, by sliding the first radial magnet 1B in the axial direction (arrow D2 in FIG. 8) and engaging the first divided magnet 111B with the first protrusions 51B and the second protrusions 52B, the first radial magnet 1B can be attached to the stator core 24B. Since the amount of sliding of the first radial magnet 1B in the axial direction can be reduced, it is also possible to simplify the assembly of the stator 20B. Note that the number of first protrusions 51B and the number of second protrusions 52B may both be one. Even in this case, the above-mentioned advantages can be obtained.

[0055] Furthermore, according to a configuration in which multiple first protrusions 51B and multiple second protrusions 52B are arranged at intervals in the axial direction, the first radial magnet 1B is supported by multiple first protrusions 51B and multiple second protrusions 52B, thereby further preventing the first radial magnet 1B from falling off.

[0056] Figure 9 is a schematic diagram showing a detailed example of the first divided magnet 111B and the second divided magnet 222B. Although not a required component of the present disclosure, both the first magnet end face 115 and the second magnet end face 125 may be inclined toward the first side as they move radially inward. When the first magnet end face 115 and the second magnet end face 125 abut each other directly or indirectly, a force F3 acts from the first magnet end face 115 to the second magnet end face 125, acting radially outward. This further prevents the first radial magnet 1 from falling off.

[0057] <Details of the first protrusion 51 and the second protrusion 52 (Third embodiment)> Figure 10 is a schematic diagram of a stator 20C (20) according to a third embodiment. Figure 10 shows the stator 20C as viewed from the inside in the radial direction, and the circumferential direction is illustrated as being aligned with the horizontal direction of the page. Figure 11 is a schematic diagram of a first radial magnet 1C (1) according to the third embodiment.

[0058] The stator 20C includes a stator core 24C (24). The stator core 24C includes a plurality of first protrusions 51C (51) spaced apart in the axial direction and a plurality of second protrusions 52C (52) spaced apart in the axial direction. The axial length of each of the first protrusions 51C and the axial length of each of the second protrusions 52C are the same. Furthermore, the axial range in which the plurality of first protrusions 51C are arranged is different from the axial range in which the plurality of second protrusions 52C are arranged. For example, the stator 20C may be configured with multiple types of laminated steel plates stacked together. The multiple types of laminated steel plates include a third laminated steel plate for forming the first protrusions 51C and a fourth laminated steel plate for forming the second protrusions 52C.

[0059] As shown in FIG. 11 , the first radial magnet 1C (1) according to the third embodiment includes a first divided magnet 111C (111) and a second divided magnet 222C (222) arranged so as to be stacked in the axial direction. In this example, a plurality of first divided magnets 111C and a plurality of second divided magnets 222C are arranged so as to be alternately stacked in the axial direction. The first divided magnet 111C engages with the first protrusion 51C, and the second divided magnet 222C engages with the second protrusion 52C. Note that both the first divided magnet 111C and the second divided magnet 222C are examples of stacked permanent magnets 12 (see FIG. 16 ) that constitute the magnet 5.

[0060] Each first divided magnet 111C (111) has a first inclined surface 61 and a first connecting surface 63. On the other hand, the second divided magnet 222C (222) has a second inclined surface 62 and a second connecting surface 64. The other circumferential end face of the first divided magnet 111C is flush with the second connecting surface 64 of the second divided magnet 222C. The one circumferential end face of the second divided magnet 222C is flush with the first connecting surface 63 of the first divided magnet 111C.

[0061] 10 and 12, an example of an assembly method for the first radial magnet 1C according to the third embodiment is shown. FIG. 12 is a schematic diagram showing the assembly process for the first radial magnet 1C. As shown in FIG. 12, the first radial magnet 1C is positioned radially inward of the first protrusions 51C and the second protrusions 52C. At this time, the first divided magnet 111C is shifted axially from the first protrusions 51C, and the second divided magnet 222C is shifted axially from the second protrusions 52C.

[0062] Next, the first radial magnet 1C is moved outward in the axial direction until it abuts against the tooth inner circumferential surface 259 (see FIG. 12). At this time, the first divided magnet 111C is offset in the axial direction from the first protrusion 51C, and the second divided magnet 222C is offset in the axial direction from the second protrusion 52C. Therefore, interference between the first divided magnet 111C and the first protrusion 51C, and between the second divided magnet 222C and the second protrusion 52C can be avoided.

[0063] The first radial magnet 1C is then slid in the axial direction (arrow E1 in FIG. 12 ) to engage the first divided magnet 111C with the first protrusions 51C, and the second divided magnet 222C with the second protrusions 52C (see FIG. 10 ). This assembles the first radial magnet 1C to the first protrusions 51C and the second protrusions 52C. By repeating this assembly process, multiple first radial magnets 1C are assembled to the stator core 24C around the circumferential direction.

[0064] According to the above configuration, the first radial magnet 1C is divided into the first divided magnets 111C and the second divided magnets 222C as the multiple permanent magnets 12, thereby reducing eddy current loss generated in the first radial magnet 1C. Furthermore, the axial length of each of the first protrusions 51C and the second protrusions 52C can be made shorter than the axial length of the teeth 25, further simplifying the configuration of the stator core 24C. Furthermore, during the assembly process of the stator 20C, the first radial magnet 1C can be moved from the radially inner side to the radially outer side with the first divided magnet 111C axially offset from the first protrusions 51C and the second divided magnet 222C axially offset from the second protrusions 52C, thereby bringing the first radial magnet 1C into contact with the tooth inner peripheral surface 259, which is an example of the core inner peripheral surface 26. The first radial magnet 1C is then slid in the axial direction (arrow E1 in FIG. 12) to engage the first divided magnet 111C with the first protrusion 51C and the second divided magnet 222C with the second protrusion 52C, thereby attaching the first radial magnet 1C to the stator core 24C. Since the amount of sliding of the first radial magnet 1C in the axial direction can be reduced, it is also possible to simplify the assembly of the stator 20C. Note that the number of first protrusions 51B and the number of second protrusions 52B may both be one. Even in this case, the above-mentioned advantages can be obtained.

[0065] <Other Magnets 5> Returning to Figure 3, the second radial magnet 2 is supported by the third protrusions 53 and the fourth protrusions 54. As already mentioned, the second radial magnet 2 has the same shape as the first radial magnet 1, and the third protrusions 53 and the fourth protrusions 54 have the same shapes as the first protrusions 51 and the second protrusions 52, respectively.

[0066] 4, the shape of the first circumferential magnet 3 will be described. One circumferential end face of the first circumferential magnet 3 has a first inclined extending surface 131 and a first extending surface 135, and the other circumferential end face has a second inclined extending surface 132 and a second extending surface 136.

[0067] The first inclined extension surface 131 and the second inclined extension surface 132 extend at an inclination such that the further they extend radially inward, the farther they are from the circumferential center of the first circumferential magnet 3. The radially inner ends of the first inclined extension surface 131 and the second inclined extension surface 132 are located radially inner than the protrusion 50. The first extension surface 135 extends radially inward from the radially inner end of the first inclined extension surface 131 and abuts against the second radial magnet 2. An adhesive may be interposed between the first extension surface 135 and the second radial magnet 2. Similarly, the second extension surface 136 extends radially inward from the radially inner end of the second inclined extension surface 132 and abuts against the first connecting surface 63 of the first radial magnet 1. An adhesive may be interposed between the second extension surface 136 and the first connecting surface 63.

[0068] The first inclined extension surface 131 abuts against the fourth protrusion 54, and the second inclined extension surface 132 abuts against the first protrusion 51. An adhesive may be interposed between the first inclined extension surface 131 and the fourth protrusion 54, and between the second inclined extension surface 132 and the first protrusion 51. As described above, a magnetic force acting radially outward acts on the first circumferential magnet 3 (arrow A3 in FIG. 3 ), and the first circumferential magnet 3 is pressed against the first protrusion 51 and the fourth protrusion 54.

[0069] The shape of the second circumferential magnet 4 will now be described. One circumferential end face of the second circumferential magnet 4 has a third inclined extending surface 133 and a third extending surface 137, and the other circumferential end face has a fourth inclined extending surface 134 and a fourth extending surface 138.

[0070] The third inclined extension surface 133 and the fourth inclined extension surface 134 extend at an inclination such that the further they extend radially inward, the farther they are from the circumferential center of the second circumferential magnet 4. The radially inner ends of the third inclined extension surface 133 and the fourth inclined extension surface 134 are located radially inward of the protrusion 50. The third extension surface 137 extends radially inward from the radially inner end of the third inclined extension surface 133 and abuts against the second connecting surface 64 of the first radial magnet 1. An adhesive may be interposed between the third extension surface 137 and the second connecting surface 64. Similarly, the fourth extension surface 138 extends radially inward from the radially inner end of the fourth inclined extension surface 134 and abuts against the second radial magnet 2. An adhesive may be interposed between the fourth extension surface 138 and the second circumferential magnet 4.

[0071] The third inclined extension surface 133 abuts against the second protrusion 52, and the fourth inclined extension surface 134 abuts against the third protrusion 53. An adhesive may be interposed between the third inclined extension surface 133 and the second protrusion 52, and between the fourth inclined extension surface 134 and the third protrusion 53. As described above, a magnetic force directed radially outward acts on the second circumferential magnet 4 (arrow A4 in FIG. 3 ), so the second circumferential magnet 4 is pressed against the second protrusion 52 and the third protrusion 53. The second circumferential magnet 4 has the same shape as the first circumferential magnet 3.

[0072] <Plate 70> Figures 13A to 13C are schematic diagrams showing multiple magnets 5. In Figures 13A to 13C, the circumferential direction is illustrated linearly, with the leftmost magnet 5 and the rightmost magnet 5 adjacent to each other in the circumferential direction. Also, in Figures 13A to 13C, the front side of the paper is the radially inner side, and the back side of the paper is the radially outer side. Figures 13A to 13C each schematically illustrate a plate 70A (70) according to a first example, a plate 70B (70) according to a second example, and a plate 70C (70) according to a third example.

[0073] As shown in Figures 13A to 13C, the plates 70A to 70C (70) extend in the circumferential direction. The plates 70A to 70C (70) are attached, for example, by adhesive to the inner circumferential surfaces 15 of two or more magnets 5 arranged continuously in the circumferential direction. The two or more magnets 5 arranged continuously include a first radial magnet 1. The plates 70A to 70C (70) are formed of a nonmagnetic material. This suppresses eddy currents from flowing in the plates 70, thereby reducing iron loss in the stator 20. The plates 70 are preferably made of a nonmagnetic and nonconductive material. Examples of such materials include glass fiber reinforced plastics (GFRP), carbon fiber reinforced plastics (CFRP), and heat-resistant resins.

[0074] In the example of FIG. 13A , multiple plates 70A are arranged at equal intervals in the circumferential direction. The magnets 5 to which each plate 70A is attached include a first radial magnet 1 and a second radial magnet 2. In the example of the same figure, the number of magnets 5 to which the plates 70A are attached is four or more, more specifically, four. The plate 70B shown in FIG. 13B is attached to the inner circumferential surface 15 of each of the multiple magnets 5 along the entire circumferential length of the stator core 24 (see FIG. 2 ). In other words, the plate 70B is a single cylindrical member attached to the inner circumferential surface 15 of each of all the magnets 5 constituting the stator 20. In the illustrated example, two plates 70B are attached to one end and the other end of the magnet 5 in the axial direction. Note that one plate 70B may be positioned so that one axial end of the magnet 5 is aligned with one axial end of the plate 70B. Similarly, the other plate 70B may be arranged so that the other axial end of the magnet 5 and the other axial end of the plate 70B are aligned.

[0075] The plate 70C shown in FIG. 13C includes a first plate portion 71 attached to two or more magnets 5 and a second plate portion 72 that is longer in the circumferential direction than the first plate portion 71. The first plate portion 71 and the second plate portion 72 are integrally configured, and the second plate portion 72 is connected to one axial end of the first plate portion 71. The number of magnets 5 to which the second plate portion 72 is attached is greater than the number of magnets 5 to which the first plate portion 71 is attached. More specifically, the magnets 5 to which the second plate portion 72 is attached include the magnet 5 to which the first plate portion 71 is attached and at least one other magnet 5. In the example shown in the figure, the second plate portion 72 is attached to all magnets 5 that make up the stator 20, and the number of magnets 5 to which the first plate portion 71 is attached is four. In the example shown in the figure, multiple first plate portions 71 are arranged at equal intervals in the circumferential direction. 13C , the number of first plate portions 71 is not limited to two or more, and may be one. Alternatively, the number of plates 70C is not limited to one, and may be two or more. In this case, a plurality of second plate portions 72 are arranged at equal intervals in the circumferential direction, and a plurality of first plate portions 71 are connected to each second plate portion 72.

[0076] According to the configuration in which the stator 20 includes the plate 70A (70), the four magnets 5 are integrated by the plate 70A, and the first protrusions 51 and the second protrusions 52 can support not only the first radial magnet 1 but also other magnets 5, such as the first circumferential magnet 3 or the second circumferential magnet 4. This realizes a stator 20 that can further prevent multiple magnets 5 from falling off. Note that the above advantages can also be obtained when plates 70B and 70C are used instead of plate 70A. For example, when plate 70B is used, all of the magnets 5 that make up the stator 20 are integrated by the attachment of plate 70B, and the magnets 5 are prevented from falling off.

[0077] Furthermore, according to a configuration in which the magnets 5 attached to the plate 70A include the first radial magnet 1 and the second radial magnet 2, the plate 70A can be attached to multiple magnets 5, including the first radial magnet 1 and the second radial magnet 2, which are two magnets 5 that have a relatively high risk of falling off, thereby more reliably preventing the multiple magnets 5 from falling off.

[0078] Furthermore, since the plate 70C includes the first plate portion 71 and the second plate portion 72, it is possible to attach the second plate portion 72 to locations where the temperature rises slowly, and to attach the first plate portion 71 to locations where the temperature rises rapidly. This makes it possible to prevent the integrated magnet 5 from falling off, and also to prevent damage to the plate 70C due to thermal deformation.

[0079] <Method of Assembling Stator 20> A method of assembling the stator 20 will be described with reference to Figs. 14 and 15. In the following description, "step" may be abbreviated as "S". Fig. 14 is a flowchart of a method of assembling the stator 20 according to an embodiment of the present disclosure. Fig. 15 is a schematic diagram showing the process of the radial magnet placement step (S11) according to an embodiment of the present disclosure. The assembly described below is performed by a worker, a robot arm operated by a worker, or a combination thereof. At the start of assembly, the holding member 209 is already in place (see Fig. 15).

[0080] First, a radial magnet arranging step (S11) is executed in which the first radial magnet 1 and the second radial magnet 2 are arranged in the stator core 24.

[0081] The radial magnet arranging step (S11) includes a first radial magnet arranging step of arranging the first radial magnet 1 and a second radial magnet arranging step of arranging the second radial magnet 2. In the first radial magnet arranging step, each of the multiple first radial magnets 1 is assembled to the first protrusions 51 and the second protrusions 52. Details of this assembly process are as described above. In this assembly process, an adhesive may be used to adhere the first radial magnet 1 to the first protrusions 51 and the second protrusions 52. In addition, in the second radial magnet arranging step, each of the multiple second radial magnets 2 is assembled to the third protrusions 53 and the fourth protrusions 54. This assembly process is similar to the first radial magnet arranging step and is achieved by sliding the second radial magnet 2 in the axial direction to engage the second radial magnet 2 with the third protrusions 53 and the fourth protrusions 54. In this assembly process, an adhesive may be used to adhere the second radial magnet 2 to the third protrusion 53 and the fourth protrusion 54 .

[0082] During execution of S11, the first radial magnet 1 and the second radial magnet 2 arranged on the stator core 24 are subjected to magnetic forces that move them toward each other in the circumferential direction (arrow W). This is because the radially inner end of the first radial magnet 1 has a south pole, and the inner end of the second radial magnet 2 has a north pole. Furthermore, the outer end of the first radial magnet 1 has a north pole, and the outer end of the second radial magnet 2 has a south pole. As a result, each protrusion 50 is subjected to a circumferential force from the first radial magnet 1 and the second radial magnet 2. In this regard, if the radial length of the protrusion 50 is configured to be 25% or less of the radial length of the first radial magnet 1 and the second radial magnet 2, the bending moment generated in the protrusion 50 can be reduced, making it possible to suppress damage to the protrusion 50.

[0083] When S11 is completed (i.e., when the first radial magnets 1 and second radial magnets 2 are arranged at equal intervals over the entire circumferential length of the stator 20), the bending moment generated in each protrusion 50 almost disappears. This is because the magnetic forces acting on the first radial magnets 1 and second radial magnets 2 cancel each other out in the circumferential direction.

[0084] After completion of S11, an assembly jig (not shown) may be temporarily placed to fix the first radial magnet 1 and the second radial magnet 2 at the assembly position. For example, the assembly jig presses the first radial magnet 1 and the second radial magnet 2 from the inside to the outside in the radial direction.

[0085] Next, a circumferential magnet arranging step (S13) is performed to arrange the first circumferential magnets 3 and the second circumferential magnets 4 in the stator core 24. For example, each of the multiple first circumferential magnets 3 is arranged between the first protrusions 51 and the fourth protrusions 54, and each of the multiple second circumferential magnets 4 is arranged between the second protrusions 52 and the third protrusions 53. More specifically, the first circumferential magnets 3 and the second circumferential magnets 4 are moved from the inside to the outside in the radial direction and arranged in a predetermined assembly position. Note that, when performing S13, an adhesive may be used to bond the first circumferential magnet 3 to the first protrusions 51 and the fourth protrusions 54, and an adhesive may be used to bond the second circumferential magnet 4 to the second protrusions 52 and the third protrusions 53. By performing S13, the first circumferential magnets 3 and the second circumferential magnets 4 are arranged in the stator core 24 (see FIG. 3 ).

[0086] Next, a plate placement step (S15) is performed in which plates 70 are placed on the inner circumferential surfaces 15 of two or more consecutively arranged magnets 5. The plates 70 are attached to the inner circumferential surfaces 15, for example, via an adhesive. This completes the assembly method for the stator 20.

[0087] <Other Embodiments (First Example)> A stator 20 according to another embodiment will be described with reference to Fig. 16. The stator 20 may further include a pressing member 80. The number of pressing members 80 in this example is the same as the number of magnets 5 that constitute the stator 20.

[0088] Each magnet 5 constituting the stator 20 includes a plurality of permanent magnets 12 stacked in the axial direction. That is, the first radial magnet 1, the second radial magnet 2, the first circumferential magnet 3, and the second circumferential magnet 4 each include a plurality of permanent magnets 12. The pressing member 80 presses the inner circumferential surface 15 of each permanent magnet 12 radially outward. An example of a more specific configuration is as follows.

[0089] The permanent magnet 12 includes a first permanent magnet 121 located closest to a first side in the axial direction and a second permanent magnet 122 located closest to a second side opposite the first side, with the first permanent magnet 121 having a first surface 121A facing the first side and the second permanent magnet 122 having a second surface 122A facing the second side. Note that the first divided magnet 111 or the second divided magnet 222 shown in Figures 6, 10, etc. may be the first permanent magnet 121 or the second permanent magnet 122.

[0090] The stator 20 further includes a first reel 91 provided on the first surface 121A and a second reel 92 provided on the second surface 122A. The first reel 91 includes a first joint portion bonded to the first surface 121A and a first cylindrical portion provided at the first joint portion. The first cylindrical portion extends linearly along the circumferential direction and faces the first surface 121A in the axial direction with a gap therebetween. The first cylindrical portion may be fixed to the first joint portion or rotatably provided at the first joint portion. Alternatively, a first cylindrical portion may be provided instead of the first cylindrical portion. The second reel 92 includes a second joint portion bonded to the second surface 122A and a second cylindrical portion provided at the second joint portion. The second cylindrical portion extends linearly along the circumferential direction and faces the second surface 122A in the axial direction with a gap therebetween. The second columnar portion may be fixed to the second joint portion or rotatably provided on the second joint portion. Also, a second cylindrical portion may be provided instead of the second columnar portion.

[0091] The pressing member 80 in this example is a wire 89 that binds together the first reel 91, the second reel 92, and each of the plurality of permanent magnets 12. The wire 89 is made of CFRP or GFRP.

[0092] The wire 89 includes a first winding portion 81 wound around a first reel 91, a first axially extending portion 83 pulled out from the first reel 91, a bent portion 85 connected to the first axially extending portion 83 and bent while abutting against the second reel 92, a second axially extending portion 84 connected to the bent portion 85, and a second winding portion 82 connected to the second axially extending portion 84 and wound around the first reel 91. Note that, for ease of viewing the drawing, the second winding portion 82 is shown separated from the first reel 91, but the second winding portion 82 is actually wound around the first cylindrical portion of the first reel 91. For the same reason, the first axially extending portion 83 is shown separated from the inner circumferential surface 15 of the permanent magnet 12, but the first axially extending portion 83 actually abuts against the inner circumferential surface 15.

[0093] The first winding portion 81 is wound around the first cylindrical portion of the first reel 91. The first axially extending portion 83 extends in the axial direction and abuts against the inner circumferential surface 15 of each of the multiple permanent magnets 12 from the radially inner side. More specifically, a groove (not shown) extending in the axial direction is provided in the inner circumferential surface 15 of each permanent magnet 12, and the first axially extending portion 83 is disposed inside the groove. The first axially extending portion 83 presses each inner circumferential surface 15 radially outward. The bent portion 85 abuts against approximately half of the outer circumferential surface of the second cylindrical portion of the second reel 92. In other examples, the bent portion 85 may be wound around the second reel 92. The second axially extending portion 84 extends in the axial direction radially outward of the first axially extending portion 83. In this example, a hole is formed in each permanent magnet 12, and the second axially extending portion 84 is disposed inside the hole. In another example, the second axially extending portion 84 may be disposed so as to abut against the outer circumferential surface of the tooth 25 (more specifically, the outer circumferential surface of the tip portion 252 shown in FIG. 2).

[0094] According to a configuration in which the stator 20 includes a pressing member 80, each permanent magnet 12 is pressed radially outward, thereby preventing at least one of the multiple permanent magnets 12 constituting each magnet 5 from falling off. In particular, according to a configuration in which the pressing member 80 presses the multiple permanent magnets 12 of the first radial magnet 1, the first radial magnet 1, which has a relatively high risk of falling off, is pressed, thereby preventing at least one of the multiple permanent magnets 12 constituting the first radial magnet 1 from falling off. Similarly, according to a configuration in which the pressing member 80 presses the multiple permanent magnets 12 constituting the second radial magnet 2, the second radial magnet 2, which has the second highest risk of falling off after the first radial magnet 1, is pressed, thereby preventing at least one of the multiple permanent magnets 12 constituting the second radial magnet 2 from falling off. Note that the pressing member 80 is not limited to the wire 89. For example, it may be a rubber band provided to bind the stator core 24 and the multiple permanent magnets 12. This embodiment also provides the above advantages. Furthermore, at least one of the pressing members 80 that press the first circumferential magnets 3 and the pressing members 80 that press the second circumferential magnets 4 may not be provided. In other words, the number of pressing members 80 may be less than the number of magnets 5 that constitute the stator 20.

[0095] Furthermore, when the pressing member 80 is configured as the first reel 91, the second reel 92, and the wire 89 that binds each of the plurality of permanent magnets 12, the second axially extending portion 84 presses each of the plurality of permanent magnets 12 radially outward due to the tension of the wire 89 that is generated when the wire 89 is wound around at least one of the first reel 91 or the second reel 92. This makes it possible to prevent at least one of the plurality of permanent magnets 12 that make up each magnet 5 from falling off.

[0096] <Other Embodiments (Second Example)> The Halbach-arranged magnet group may be eight magnets 5 arranged continuously in the circumferential direction. In this case, the arrangement is a so-called dual Halbach arrangement, and the magnetization direction components of the first circumferential magnet 3 and the second circumferential magnet 4 adjacent to the first radial magnet 1 in the circumferential direction each have not only a circumferential component but also a radial component.

[0097] <Summary> The contents described in the above-described embodiments can be understood, for example, as follows.

[0098] 1) A stator (20) according to an embodiment of the present disclosure is a stator comprising: a stator core (24, 28); and a plurality of magnets (5) including a magnet group (for example, four magnets 5 arranged continuously in the circumferential direction) arranged circumferentially on the inner circumferential side of the stator core, the magnet group being arranged in a Halbach array, wherein the magnet group has a first radial magnet (1) magnetized radially outward, the first radial magnet having: an outer circumferential surface (65); a first inclined surface (61) connected to one circumferential end (65a) of the outer circumferential surface and inclined so as to approach the circumferential center (imaginary line K1) of the first radial magnet as it moves inward in the radial direction; and a second inclined surface (62) connected to the other circumferential end (65b) of the outer circumferential surface and inclined so as to approach the center of the first radial magnet as it moves inward in the radial direction, and the stator core is The core magnet includes an inner peripheral surface (26) which is an inner peripheral surface on which the plurality of magnets are arranged; a first protrusion (51) which protrudes radially inward from the inner peripheral surface of the core and has a first support surface (55) that supports the first inclined surface; and a second protrusion (52) which protrudes radially inward from the inner peripheral surface of the core and has a second support surface (56) that supports the second inclined surface, wherein both the first support surface and the second support surface are inclined with respect to the radial direction and are inclined so as to move toward the center of the first radial magnet as they move radially inward.

[0099] According to the configuration of 1) above, because the first support surface and the second support surface are inclined relative to the radial direction, the radially outward forces (F1, F2) acting on the first radial magnet from each of the first support surface and the second support surface can be increased, preventing the first radial magnet from falling off. Furthermore, because the force acting on the first radial magnet can be increased without increasing the radial length of each of the first support surface and the second support surface, the radial length of each of the first protrusions and the second protrusions can be shortened, simplifying the configuration of the stator core. As a result, a stator that can prevent at least one of the multiple magnets from falling off with a simple configuration is realized.

[0100] 2) In some embodiments, the stator is as described in 1) above, wherein the first radial magnet includes a first divided magnet (5) and a second divided magnet (5) arranged so as to be stacked in the axial direction, the first divided magnet has the first inclined surface and the second inclined surface and is supported by the first protrusion and the second protrusion, and the second divided magnet is arranged so as to be offset from the first protrusion and the second protrusion in the axial direction and is arranged between the tip (511) of the first protrusion and the tip (522) of the second protrusion in the circumferential direction.

[0101] According to the configuration of 2), the first radial magnet is divided into multiple permanent magnets, thereby reducing eddy current loss generated in the first radial magnet. Furthermore, the axial length of each of the first and second protrusions can be made shorter than the axial length of the teeth, further simplifying the configuration of the stator core. Furthermore, during the stator assembly process, the first radial magnet can be moved from the radially inner side to the radially outer side while the first divided magnet is axially offset from the first and second protrusions, thereby contacting the first radial magnet with the inner circumferential surface of the core. The first radial magnet can then be attached to the stator core by sliding it axially to engage the first divided magnet with the first and second protrusions. Since the amount of sliding of the first radial magnet in the axial direction can be reduced, the stator assembly can also be facilitated.

[0102] 3) In some embodiments, the stator is as described in 1) above, wherein the first radial magnet includes a first divided magnet (5) and a second divided magnet (5) arranged so as to be stacked in the axial direction, the first protrusion and the second protrusion are arranged at different positions from each other in the axial direction, the first divided magnet has the first inclined surface and is supported by the first protrusion, and the second divided magnet has the second inclined surface and is supported by the second protrusion.

[0103] According to the configuration of 3), the first radial magnet is divided into multiple permanent magnets, thereby reducing eddy current loss generated in the first radial magnet. Furthermore, the axial length of each of the first and second protrusions can be made shorter than the axial length of the teeth, further simplifying the configuration of the stator core. Furthermore, during the stator assembly process, the first radial magnet can be moved from the radially inner side to the radially outer side with the first divided magnet axially offset from the first protrusion and the second divided magnet axially offset from the second protrusion, thereby abutting the first radial magnet against the inner circumferential surface of the core. The first radial magnet can then be attached to the stator core by sliding the first radial magnet axially to engage the first divided magnet with the first protrusion and the second divided magnet with the second protrusion. The reduced axial sliding of the first radial magnet also facilitates stator assembly.

[0104] 4) In some embodiments, the stator is as described in 2) or 3) above, wherein the first radial magnet includes a plurality of the first divided magnets and a plurality of the second divided magnets stacked so as to be alternately arranged in the axial direction, and the stator core includes a plurality of the first protrusions arranged at intervals in the axial direction, and a plurality of the second protrusions arranged at intervals in the axial direction.

[0105] According to the configuration of 4) above, the first radial magnets are supported by the plurality of first protrusions and the plurality of second protrusions, so that the first radial magnets can be further prevented from falling off.

[0106] 5) In some embodiments, the stator is the one described in any one of 2) to 4) above, wherein the first divided magnet has a first magnet end face (115) which is an end face on a first side in the axial direction, the second divided magnet has a second magnet end face (125) which is an end face on a second side in the axial direction and abuts the first magnet end face, and both the first magnet end face and the second magnet end face are inclined so as to be closer to the first side in the axial direction as they move radially inward.

[0107] According to the configuration of 5) above, a radially outward force acts from the first magnet end face of the first divided magnet supported by at least the first protrusion of either the first or second protrusion to the second magnet end face of the second divided magnet. This prevents the second divided magnet from falling off. This further prevents the first radial magnet from falling off.

[0108] 6) In some embodiments, in the stator described in 1) above, at least one of the first protrusion and the second protrusion extends continuously in the axial direction over the entire axial length of the core inner circumferential surface.

[0109] According to the configuration of 6) above, the axial range in which the first radial magnet is supported by at least one of the first protrusions or the second protrusions can be expanded, so that the first radial magnet can be further prevented from falling off.

[0110] 7) In some embodiments, the stator is described in any one of 1) to 6) above, wherein the stator core further includes a plurality of teeth spaced apart in the circumferential direction, and the core inner surface includes a teeth inner surface (66) that is the inner surface of at least one of the plurality of teeth.

[0111] According to the above configuration 7), the first and second projections can be integrated with the plurality of teeth, which further simplifies the configuration of the stator.

[0112] 8) In some embodiments, the stator according to any one of 1) to 7) above further comprises a plate (70) extending in the circumferential direction and attached to the inner circumferential surface (5) of each of the two or more magnets, including the first radial magnet.

[0113] According to the configuration of 8) above, the first radial magnet supported by the first and second protrusions is connected to another magnet via a plate, so that the other magnet is also indirectly supported by the first and second protrusions, realizing a stator that can prevent multiple magnets from falling off.

[0114] 9) In some embodiments, the stator is as described in 8) above, wherein the magnet group further includes a second radial magnet (2) magnetized radially inward, and the magnets to which the plate is attached include the first radial magnet and the second radial magnet.

[0115] According to the configuration 9) above, the plate is attached to multiple magnets, including the first radial magnet and the second radial magnet, which are two magnets that are relatively at risk of falling off, so that the falling off of multiple magnets can be more reliably prevented.

[0116] 10) In some embodiments, the stator is as described in 8) above, wherein the plate is a single member attached to the inner circumferential surface of each of the plurality of magnets over the entire circumferential length of the stator core.

[0117] According to the above configuration 10), all the magnets are integrated by the plate, and the magnets are prevented from falling off.

[0118] 11) In some embodiments, the stator is as described in 10) above, wherein the plate includes: a first plate portion (71) attached to the two or more magnets; and a second plate portion (72) connected to one axial end of the first plate portion and longer in the circumferential direction than the first plate portion, and the magnet to which the second plate portion is attached includes the two or more magnets to which the first plate portion is attached and at least one other magnet.

[0119] According to the configuration of 11), it is possible to attach the second plate portion to the location where the temperature rises slowly, and the first plate portion to the location where the temperature rises rapidly, which prevents the integrated magnet from falling off and also prevents damage to the plate due to thermal deformation.

[0120] 12) In some embodiments, the stator is described in any one of 1) to 11) above, wherein the first radial magnet includes a plurality of permanent magnets (12) stacked in the axial direction, and the stator core further includes a pressing member (80) that presses the inner circumferential surface (5) of each permanent magnet outward in the radial direction.

[0121] According to the configuration of 12) above, the first radial magnet, which has a relatively high risk of falling off, is pressed radially outward, thereby preventing at least one of the multiple permanent magnets constituting the first radial magnet from falling off.

[0122] 13) In some embodiments, the stator is the one described in 12) above, wherein the plurality of permanent magnets include a first permanent magnet (5) located at the first side in the axial direction, and a second permanent magnet (5) located at the second side in the axial direction, and the stator further includes a first reel (91) provided on a first surface (121A) of the first permanent magnet facing the first side, and a second reel (92) provided on a second surface (122A) of the second permanent magnet facing the second side, and the pressing member is a wire that binds together the first reel, the second reel, and each of the plurality of permanent magnets.

[0123] According to the configuration of 13), the permanent magnets are pressed radially outward by tension generated by winding the wire around at least one of the first reel and the second reel, thereby preventing at least one of the permanent magnets constituting the magnet from falling off.

[0124] 14) A magnetic gear electric machine (10) according to at least one embodiment of the present disclosure comprises: a stator (20) according to any one of 1) to 13) above; a pole piece rotor (30) including a plurality of pole pieces arranged in the circumferential direction and radially inward of the stator; and a magnet rotor (40) including an inner magnet arranged radially inward of the plurality of pole pieces.

[0125] The configuration 14) above provides the same advantages as those of the configuration 1).

[0126] 15) A method for assembling a stator (20) according to at least one embodiment of the present invention, comprising a step (S11) of sliding the first radial magnet (1) in the axial direction to engage the first inclined surface (61) with the first protrusion (51) and to engage the second inclined surface (62) with the second protrusion (52).

[0127] The configuration 15) above provides the same advantages as those of 1).

[0128] 1: First radial magnet 2: Second radial magnet 3: First circumferential magnet 4: Second circumferential magnet 5: Magnet 10: Magnetic gear electric machine 15: Inner peripheral surface 20: Stator 24, 28: Stator core 25: Teeth 26: Core inner peripheral surface 29: Yoke 30: Pole piece rotor 40: Magnet rotor 50: Protrusion 51: First protrusion 52: Second protrusion 53: Third protrusion 54: Fourth protrusion 55: First support surface 56: Second support surface 61: First inclined surface 62: Second inclined surface 65: Outer peripheral surface 65a: One end 65b: Other end 66: Inner peripheral surface 70: Plate 71: First plate portion 72: Second plate portion 80: Pressing member 91: First reel 92: Second reel 111: First divided magnet 115: First magnet end face 121: First permanent magnet 121A: First surface 122: Second permanent magnet 122A: Second surface 125: Second magnet end face 150: Mounting member 152: Extension portion 161: Engagement hole portion 166: Engagement protrusion portion 170: Pressing rod 201: Slot opening 222: Second divided magnet 259: Teeth inner surface 511, 522: Tip G1: Outer air gap G2: Inner air gap K1: Virtual line

Claims

1. A stator comprising: a stator core; and a plurality of magnets including a magnet group arranged continuously in a circumferential direction on an inner periphery side of the stator core, the magnet group being arranged in a Halbach array; the magnet group having a first radial magnet magnetized on the radially outward side, the first radial magnet having: an outer periphery surface; a first inclined surface connected to one circumferential end of the outer periphery surface and inclined toward the circumferential center of the first radial magnet as it moves inward in the radial direction; and a second inclined surface connected to the other circumferential end of the outer periphery surface and inclined toward the center of the first radial magnet as it moves inward in the radial direction; and the stator core comprising: a core inner periphery surface which is an inner periphery surface on which the plurality of magnets are arranged; and a first protrusion protruding radially inward from the core inner periphery surface, the first protrusion having a first support surface which supports the first inclined surface. a second protrusion protruding radially inward from the inner circumferential surface of the core, the second protrusion having a second support surface supporting the second inclined surface, wherein both the first support surface and the second support surface are inclined with respect to the radial direction and inclined toward the center of the first radial magnet as they move radially inward.

2. A stator as described in claim 1, wherein the first radial magnet includes a first divided magnet and a second divided magnet arranged so as to be stacked in the axial direction, the first divided magnet has the first inclined surface and the second inclined surface and is supported by the first protrusion and the second protrusion, and the second divided magnet is arranged so as to be offset from the first protrusion and the second protrusion in the axial direction and is arranged between the tip of the first protrusion and the tip of the second protrusion in the circumferential direction.

3. A stator as described in claim 1, wherein the first radial magnet includes a first divided magnet and a second divided magnet arranged so as to be stacked in the axial direction, the first protrusion and the second protrusion are arranged at different positions from each other in the axial direction, the first divided magnet has the first inclined surface and is supported by the first protrusion, and the second divided magnet has the second inclined surface and is supported by the second protrusion.

4. A stator as described in claim 2 or 3, wherein the first radial magnet includes a plurality of the first divided magnets and a plurality of the second divided magnets stacked so as to be arranged alternately in the axial direction, and the stator core includes a plurality of the first protrusions arranged at intervals in the axial direction, and a plurality of the second protrusions arranged at intervals in the axial direction.

5. A stator as described in claim 3, wherein the first divided magnet has a first magnet end face which is an end face on a first side in the axial direction, and the second divided magnet has a second magnet end face which is an end face on a second side in the axial direction and abuts the first magnet end face, and both the first magnet end face and the second magnet end face are inclined so as to approach the first side in the axial direction as they move inward in the radial direction.

6. A stator as set forth in claim 1, wherein at least one of said first projections and said second projections extends continuously in the axial direction over the entire axial length of said core inner peripheral surface.

7. A stator according to any one of claims 1 to 3, wherein the stator core further includes a plurality of teeth arranged at intervals in the circumferential direction, and the core inner peripheral surface includes a teeth inner peripheral surface which is the inner peripheral surface of at least one of the plurality of teeth.

8. A stator as claimed in any one of claims 1 to 3, further comprising a plate extending in the circumferential direction, the plate being attached to an inner circumferential surface of each of two or more of the magnets including the first radial magnet.

9. The stator according to claim 8, wherein the magnet group further includes a second radial magnet magnetized radially inward, and the magnets to which the plate is attached include the first radial magnet and the second radial magnet.

10. A stator as set forth in claim 8, wherein said plate is a single member attached to said inner circumferential surface of each of said plurality of magnets over the entire length of said stator core in the circumferential direction.

11. A stator as described in claim 10, wherein the plate includes a first plate portion attached to the two or more magnets, and a second plate portion connected to one axial end of the first plate portion and longer in the circumferential direction than the first plate portion, and the magnet to which the second plate portion is attached includes the two or more magnets to which the first plate portion is attached and at least one other magnet.

12. A stator as claimed in any one of claims 1 to 3, wherein the first radial magnet includes a plurality of permanent magnets stacked in the axial direction, and the stator core further includes a pressing member that presses the inner circumferential surface of each permanent magnet outward in the radial direction.

13. A stator as described in claim 12, wherein the plurality of permanent magnets include a first permanent magnet located on the first side in the axial direction, and a second permanent magnet located on the second side in the axial direction, the stator further comprising: a first reel provided on a first surface of the first permanent magnet facing the first side, and a second reel provided on a second surface of the second permanent magnet facing the second side, and the pressing member is a wire binding the first reel, the second reel, and each of the plurality of permanent magnets.

14. A magnetic gear electric machine comprising: a stator according to any one of claims 1 to 3; a pole piece rotor including a plurality of pole pieces arranged in the circumferential direction and radially inward of the stator; and a magnet rotor including an inner magnet arranged radially inward of the plurality of pole pieces.

15. A method for assembling a stator according to any one of claims 1 to 3, comprising the step of sliding the first radial magnet in the axial direction to engage the first inclined surface with the first protrusion and to engage the second inclined surface with the second protrusion.

Images