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

Abstract

This stator is composed of a Halbach-arrayed magnet group which includes: a first radial magnet magnetized outward in the radial direction; a first circumferential magnet positioned on one side in the circumferential direction of the first radial magnet and magnetized toward the one side; and a second circumferential magnet positioned on the other side in the circumferential direction of the first radial magnet and magnetized toward the other side. At least one of one end surface and the other end surface in the circumferential direction of the first radial magnet has a first inclined end surface that slopes toward the center side in the circumferential direction of the first radial magnet as the surface extends toward the inside in the radial direction. At least one of the other end surface in the circumferential direction of the first circumferential direction magnet and one end surface in the circumferential direction of the second circumferential direction magnet has a first abutting / inclined end surface that slopes toward the center side in the circumferential direction of the first radial direction magnet as the surface extends toward the inside in the radial direction and that abuts the first inclined end surface.

Description

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

[0001] This application claims priority to Japanese Patent Application No. 2023-122922, 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 this application have devised the application of a Halbach array, which concentrates magnetic flux radially inward from the stator, to the stator magnet arrangement. 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, the magnetic force that radially magnetized magnets experience is a relatively large force that faces radially inward, making the magnets particularly susceptible to dislodgment.

[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.

[0006] A stator according to at least one embodiment of the present disclosure comprises: a stator core including a plurality of teeth arranged at intervals in a circumferential direction based on an axis; and a plurality of magnets including a magnet group arranged continuously in the circumferential direction radially inward of the plurality of teeth, the magnet group being arranged in a Halbach array, wherein the magnet group includes: a first radial magnet magnetized on the outer side in the radial direction; a first circumferential magnet located on one side in the circumferential direction of the first radial magnet and magnetized on the one side; and a second circumferential magnet located on the other side in the circumferential direction of the first radial magnet and magnetized on the other side, wherein at least one of one end face or the other end face in the circumferential direction of the first radial magnet has a first inclined end face that inclines so as to approach a center side in the circumferential direction of the first radial magnet as it moves inward in the radial direction, At least one of the other end face in the circumferential direction of the first circumferential magnet or one end face in the circumferential direction of the second circumferential magnet has a first abutting inclined end face that inclines toward the center of the circumferential direction of the first radial magnet as it moves toward the inside in the radial direction and abuts against the first inclined end face.

[0007] A magnetic gear electric machine according to 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 first radial magnet that is magnetized on the outer side in the radial direction; a first circumferential magnet that is located on one side in the circumferential direction of the first radial magnet and magnetized on the one side; and a second circumferential magnet that is located on the other side in the circumferential direction of the first radial magnet and magnetized on the other side; and a stator assembly method according to an embodiment of the present disclosure, the stator assembly method including: a stator core including a plurality of teeth that are arranged at intervals in a circumferential direction based on an axis; a plurality of magnets including a magnet group that is continuously arranged in the circumferential direction radially inward of the plurality of teeth, the magnet group being arranged in a Halbach array; and a plurality of protrusions that protrude toward the inner side in the radial direction of the plurality of teeth and are arranged alternately with the plurality of magnets in the circumferential direction, the magnet group including: a first radial magnet that is magnetized on the outer side in the radial direction; a first circumferential magnet that is located on one side in the circumferential direction of the first radial magnet and magnetized on the one side; and a second circumferential magnet that is located on the other side in the circumferential direction of the first radial magnet and magnetized on the other side; and at least one of one end face or the other end face in the circumferential direction of the first radial magnet has a first inclined end face that is inclined so as to approach a center side in the circumferential direction of the first radial magnet as it goes inward in the radial direction, At least one of the other end face in the circumferential direction of the first circumferential magnet or one end face in the circumferential direction of the second circumferential magnet has a first abutting inclined end face that inclines toward the center of the first radial magnet in the circumferential direction as it moves toward the inside in the radial direction and abuts against the first inclined end face, and the method for assembling the stator includes the steps of: arranging the first radial magnet between any two of the protrusions that are lined up consecutively in the circumferential direction; and, after performing the step of arranging the first radial magnet, arranging the first circumferential magnet and the second circumferential magnet between two other protrusions that are lined up consecutively in the circumferential direction.

[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.

[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. 2; FIG. 4 is a schematic diagram showing forces acting on a plurality of magnets according to an embodiment; FIG. 5 is a schematic diagram of a plate according to a first embodiment; FIG. 6 is a schematic diagram of a plate according to a second embodiment; FIG. 7 is a schematic diagram of a plate according to a third embodiment; FIG. 8 is a schematic diagram of a stator including plates according to an embodiment; FIG. 9 is a flowchart of a method of assembling a stator according to an embodiment; FIG. 10 is a schematic diagram showing radial magnet arrangement steps according to an embodiment; FIG. 11 is a schematic diagram showing circumferential magnet arrangement steps according to an embodiment; FIG. 12 is a schematic diagram of a stator according to another embodiment (first example); FIG. 13 is a schematic diagram of a stator according to another embodiment (second example); FIG. 14 is a schematic diagram of a stator according to another embodiment (second example); FIG. 15 is a schematic diagram of a stator according to another embodiment (third example); FIG. 16 is a schematic diagram of a stator according to another embodiment (fourth example); FIG. 17 is a schematic diagram of a stator according to another embodiment (fifth example).

[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 extending in the circumferential direction, a plurality of teeth 25 protruding radially inward from the stator core 24, a stator coil 27 wound around the plurality of teeth 25, and a plurality of magnets 5 supported by the plurality of 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 plurality of magnets 5 are arranged on the inner circumferential surfaces of the plurality of teeth 25. 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 of the teeth 25, or may be a configuration in which the magnets 5 are attached to the inner circumferential surfaces of the teeth 25 via another member (see FIG. 10 ).

[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 faces the magnets 5 in the radial direction across an outer air gap G1. The annular body 35 also includes a plurality of pole pieces 36 and a plurality of non-magnetic bodies (not shown) arranged alternately along the circumferential direction. The connecting members 31 and 32 extend radially. The connecting members 31 and 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 piece 36 may be a plurality of electromagnetic steel plates stacked in the axial direction, or may be at least one powder magnetic core extending in the axial direction, or may be a combination of these.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 2 is a schematic diagram of the stator 20 according to an embodiment of the present disclosure. The stator 20 includes a cylindrical stator core 24 extending along the axial direction, a plurality of teeth 25 spaced apart in the circumferential direction inside the stator core 24, and stator coils 27 provided on the plurality of teeth 25.

[0022] The teeth 25 all extend in the axial direction. Each tooth 25 includes a protruding portion 251 that protrudes radially inward from the stator core 24 and a tip portion 252 that is connected to the tip of the protruding portion 251. The stator core 24, 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 wound around the protruding portion 251. A slot opening 201 is formed as a space between two circumferentially adjacent tip portions 252, and a retaining member 209, which may be made of, for example, a resin material, is disposed in the slot opening 201. The retaining member 209 is retained by the circumferential ends of the two tip portions 252.

[0023] The stator 20 further includes a plurality of protrusions 50 that protrude radially inward beyond the plurality of teeth 25. The protrusions 50 illustrated in FIG. 2 include a protrusion 53 that protrudes radially inward from a tip 252 of the tooth 25, and a protrusion 54 that protrudes radially inward from the retaining member 209. The protrusion 53 is integrally formed from the same soft magnetic material as the tip 252, and the protrusion 54 is integrally formed from the same resin material as the retaining member 209. The protrusions 53, 54 have the same shape. Note that the protrusion 50 does not necessarily have to include the protrusion 54, and the plurality of protrusions 50 may be formed only by the plurality of protrusions 53. In the following description, the protrusions 53, 54 may be referred to as "protrusions 50" without distinguishing between them.

[0024] The stator 20 further includes a plurality of magnets 5 arranged alternately in the circumferential direction with the plurality of protrusions 50. The plurality of magnets 5 are arranged radially inward of the plurality of teeth 25, and each magnet 5 is sandwiched between two of the plurality of protrusions 50 that are adjacent in the circumferential direction.

[0025] 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 such magnet groups are arranged. In FIG. 2, 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. 13). In this specification, for convenience of explanation, each magnet 5 extending in the axial direction (see FIG. 2) is counted as one magnet.

[0026] In the following description, the group of magnets arranged in a Halbach array may be referred to as "four magnets 5." Furthermore, the end face of the magnet 5 on one circumferential side is referred to as "one end face 6," and the end face of the magnet 5 on the other circumferential side is referred to as "the other end face 7." In the example of Figure 2, the clockwise side is one side, and the counterclockwise side is the other side. Although not shown, the counterclockwise side may be one side, and the clockwise side may be the other side.

[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. At least one of the one end face 11 (6) or the other end face 111 (7) of the first radial magnet 1 (magnet 5) has a first inclined end face 61. The first inclined end face 61 is inclined so as to approach the circumferential center C1 of the first radial magnet 1 as it moves radially inward. In the example of Figure 3, both the one end face 11 and the other end face 111 have a first inclined end face 61. As a more specific example, the first radial magnet 1 has a symmetrical shape in the circumferential direction. In other words, at least a portion of the first radial magnet 1 has a shape in which the circumferential length becomes shorter as it moves radially inward.

[0029] One end face 22 (6) of the second radial magnet 2 (magnet 5) has a second inclined end face 62. The second inclined end face 62 inclines toward the center C2 of the second radial magnet 2 in the circumferential direction as it moves radially inward. As a more specific example, the second radial magnet 2 has a circumferentially symmetrical shape. In other words, the other end face 222 (7) of the second radial magnet 2 (magnet 5) also has a second inclined end face 62, and at least a portion of the second radial magnet 2 has a shape in which the circumferential length decreases as it moves radially inward. The inclination angle (acute angle) of the second inclined end face 62 relative to the radial direction is the same as the inclination angle (acute angle) of the first inclined end face 61 relative to the radial direction. In this example, when viewed in the axial direction, the second radial magnet 2 has the same shape as the first radial magnet 1.

[0030] The other end face 333 (7) of the first circumferential magnet 3 (magnet 5) is adjacent to one end face 11 of the first radial magnet 1 in the circumferential direction, and one end face 44 (6) of the second circumferential magnet 4 (magnet 5) is adjacent to the other end face 111 of the first radial magnet 1 in the circumferential direction. At least one of the other end face 333 of the first circumferential magnet 3 or the one end face 44 of the second circumferential magnet 4 has a first abutting inclined end face 49. The first abutting inclined end face 49 is inclined toward the center C1 of the first radial magnet 1 as it moves radially inward. In the example of FIG. 3 , the other end face 333 and the one end face 44 each have the first abutting inclined end face 49.

[0031] Additionally, the other end face 444 (7) of the second circumferential magnet 4 (magnet 5) has a second inclined abutment end face 48. The second inclined abutment end face 48 is inclined radially inward toward the center C2 of the second radial magnet 2. The second circumferential magnet 4 has a symmetrical shape in the circumferential direction, and the inclination angle (acute angle) of the second inclined abutment end face 48 relative to the radial direction is the same as the inclination angle (acute angle) of the first inclined abutment end face 49 relative to the radial direction.

[0032] Furthermore, one end face 33 (6) of the first circumferential magnet 3 (magnet 5) also has a second abutting inclined end face 48. The second abutting inclined end face 48 of the first circumferential magnet 3 is inclined radially inward so as to be closer to the center C2 of the second radial magnet 2, which is located on one side of the first circumferential magnet 3 in the circumferential direction. In this example, when viewed in the axial direction, the shape of the first circumferential magnet 3 is the same as the shape of the second circumferential magnet 4.

[0033] Although not an essential component of the present disclosure, the stator 20 illustrated in Fig. 3 includes a plurality of intervening members 90 arranged radially inward of the plurality of protrusions 50. Each intervening member 90 is sandwiched between any two circumferentially adjacent magnets 5 among the plurality of magnets 5. In other words, the first abutment inclined end surface 49 in the example shown in the figure indirectly abuts against the first inclined end surface 61 of the first radial magnet 1 via the intervening member 90. Furthermore, the second abutment inclined end surface 48 indirectly abuts against the second inclined end surface 62 of the second radial magnet 2 via the intervening member 90.

[0034] The interposing member 90 has a plate shape extending in the axial direction. In some embodiments, a radially outer end of the interposing member 90 abuts a radially inner end of the protrusion 50. The interposing member 90 is preferably made of an insulating material. The interposing member 90 may be an adhesive or a resin member.

[0035] FIG. 4 is a schematic diagram showing forces acting on multiple magnets 5 according to an embodiment of the present disclosure. Arrows A1 to A4 indicate the magnetic forces 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 received by the first radial magnet 1. Similarly, arrow A2 indicates the direction and magnitude of the magnetic force received by the second radial magnet 2, arrow A3 indicates the direction and magnitude of the magnetic force received by the first circumferential magnet 3, and arrow A4 indicates the direction and magnitude of the magnetic force received by the second circumferential magnet 4. The lengths of arrows A1 to A4 indicate the magnitude of the magnetic force. The direction and magnitude of these magnetic forces can be determined by simulation. As can be seen from the figure, the first radial magnet 1 receives the largest magnetic force directed radially inward, and the risk of the first radial magnet 1 becoming disengaged from the teeth 25 is higher than the risk of the other magnets 5 becoming disengaged from the teeth 25.

[0036] In this regard, with the configuration in which the first inclined contact end surface 49 indirectly contacts the first inclined end surface 61 via the intervening member 90, the force F acting from the first inclined contact end surface 49 to the first inclined end surface 61 includes a component force R that acts radially outward. The application of force R can prevent the first radial magnet 1 from coming off the teeth 25. This achieves a stator 20 that can prevent at least one of the multiple magnets 5 from falling off.

[0037] Of the one end face 11 or the other end face 111 of the first radial magnet 1, the other end face 111 may not have the first inclined end face 61. In this case, the one end face 44 of the second circumferential magnet 4 does not have the first abutting inclined end face 49. Alternatively, the one end face 11 may not have the first inclined end face 61. In this case, the other end face 333 of the first circumferential magnet 3 does not have the first abutting inclined end face 49. Also, the second radial magnet 2 may not have the second inclined end face 62. Furthermore, the stator 20 may not have the intervening member 90 (details will be described later). In any embodiment, the radial force R generated by the abutment between the first abutting inclined end face 49 and the first inclined end face 61 acts on the first radial magnet 1, thereby obtaining the above-mentioned advantages.

[0038] Furthermore, according to a configuration in which one end face 11 and the other end face 111 of the first radial magnet 1 each have a first inclined end face 61, and the first circumferential magnet 3 and the second circumferential magnet 4 each have a first abutting inclined end face 49, a force R directed radially outward is generated at each of the one end face 11 and the other end face 111, thereby further preventing the first radial magnet 1 from coming off the teeth 25.

[0039] 4, a magnetic force directed radially inward also acts on the second radial magnet 2. In this regard, according to a configuration in which the second abutment inclined end surface 48 indirectly abuts against the second inclined end surface 62 via the intervening member 90, a force (not shown) directed radially outward acts on the second radial magnet 2. This makes it possible to prevent the second radial magnet 2 from coming off the teeth 25, thereby realizing a stator 20 that can prevent the plurality of magnets 5 from falling off.

[0040] Furthermore, with a configuration in which the other end face 222 of the second radial magnet 2 has the second inclined end face 62 and the first circumferential magnet 3 located on the other circumferential side of the second radial magnet 2 has the second abutting inclined end face 48, a force directed radially outward is generated at each of the one end face 22 and the other end face 222. This further prevents the second radial magnet 2 from coming off the teeth 25.

[0041] Furthermore, when the stator 20 is configured to include multiple intervening members 90, the intervening members 90 are interposed between two adjacent magnets 5, thereby preventing the dispersion of the force transmitted from one of the two adjacent magnets 5 to the other. As a more specific example, the first abutment inclined end surface 49 can be in stable surface contact with the first inclined end surface 61 via the intervening members 90, preventing the dispersion of the force F applied from the first abutment inclined end surface 49 to the first inclined end surface 61. This increases the radial force R acting on the first radial magnet 1, preventing the first radial magnet 1 from coming off the multiple teeth 25. This further prevents the multiple magnets 5 from falling off.

[0042] <Relationship between Protrusions 50 and Magnets 5> Returning to FIG. 3 , each protrusion 50 includes a first end face 51 and a second end face 52, which are both circumferential end faces. Furthermore, both the first end face 6 and the other end face 7 of each magnet 5 have a protrusion abutment surface 8 that abuts against the protrusion 50. The protrusion abutment surface 8 is located radially outward from the first inclined end face 61 and the first abutment inclined end face 49. More specifically, the protrusion abutment surface 8 is located radially outward from the first inclined end face 61, the second inclined end face 62, the first abutment inclined end face 49, and the second abutment inclined end face 48. In the example of FIG. 3 , the two protrusion abutment surfaces 8 of each magnet 5 abut against the second end face 52 of the protrusion 50 on one side and against the first end face 51 of the protrusion 50 on the other side. As a result, each magnet 5 is sandwiched between the two protrusions 50. An intervening member 90 may be interposed between each magnet 5 and the protrusion 50 .

[0043] 3, the radial length (dimension M) of each protrusion 50 is less than half, more specifically less than one-third, and even more specifically less than one-quarter of the radial length of each of the multiple magnets 5. The radial length of each protrusion 50 is also greater than one-fifth of the radial length of each magnet 5. Furthermore, in this example, the circumferential length (maximum circumferential length) of each protrusion 50 is less than one-quarter of the radial length of each protrusion 50.

[0044] By configuring the dimension M to be equal to or less than half the radial length of the magnet 5, the radial length of each protrusion 50 can be shortened. This allows each of the multiple magnets 5 to be moved from the radially inner side to a predetermined assembly position where it is sandwiched between two protrusions 50 during the assembly process of the stator 20 (details of the assembly method will be described later). Conventionally, the magnet 5 had to be slid axially to a predetermined assembly position where it is sandwiched between two fingers (not shown in this document). However, because the fingers and magnets 5 generally have a shape that extends axially, the sliding distance of the magnet 5 is large, which poses a problem of the assembly process of the magnet 5 being time-consuming. In this regard, with the above configuration, each magnet 5 is moved radially, thereby reducing the movement distance of the magnet 5 and improving the assembly of the stator 20.

[0045] 3, the first end face 51 and the second end face 52 extend radially. In other words, the first end face 51 and the second end face 52 are planes parallel to the radial direction. According to the above configuration, the configuration in which the first end face 51 and the second end face 52 extend radially results in a shape of the protrusion 50 whose circumferential length decreases toward the radially inner side, facilitating the process of moving the magnet 5 from the radially outer side to a predetermined assembly position. This further simplifies the assembly process of the magnet 5.

[0046] In the example shown in FIG. 3 , the protrusion abutment surface 8 of each magnet 5 is a plane extending radially. In other words, the protrusion abutment surface 8 is a plane parallel to the radial direction. This configuration widens the radial range in which the protrusion abutment surface 8 and the protrusions 50 abut. As a result, even if the radial length of the protrusions 50 is short, each magnet 5 is firmly sandwiched between the two protrusions 50. This achieves a stator 20 that prevents multiple magnets 5 from falling off. Furthermore, even if at least one of the first circumferential magnet 3 or the second circumferential magnet 4 has a first abutment inclined end surface 49 and the circumferential magnet has a shape in which its circumferential length increases radially inward, the protrusion abutment surface 8 extends radially, making it easy to move the circumferential magnet to the predetermined assembly position where it is sandwiched between the two protrusions 50. This further simplifies the assembly process of the stator 20.

[0047] 3, the radial length of the projection abutment surface 8 is less than half, more specifically less than one-third, and even more specifically less than one-quarter of the radial length of each magnet 5. With this configuration, the distance that the projection abutment surface 8 moves radially while sliding against the projection 50 during the magnet assembly process can be shortened, further simplifying the assembly process of the stator 20.

[0048] <Plate 70> Figures 5A to 5C are schematic diagrams showing multiple magnets 5. In Figures 5A to 5C, 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 5A to 5C, the front side of the paper is the radially inner side, and the back side of the paper is the radially outer side. Figures 5A to 5C are schematic diagrams of a plate 70A (70) according to the first embodiment, a plate 70B (70) according to the second embodiment, and a plate 70C (70) according to the third embodiment, respectively.

[0049] As shown in FIGS. 5A to 5C , 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 (see FIG. 6 ) 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.

[0050] In the example of FIG. 5A , 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. 5B 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 magnets 5 constituting the stator 20. In the illustrated example, two plates 70B are attached to one axial end and the other axial end of the magnet 5, respectively. 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.

[0051] The plate 70C shown in FIG. 5C includes a first plate portion 71 attached to two or more magnets 5 described above 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. 5C , 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.

[0052] Fig. 6 is a schematic diagram of the stator 20 including a plate 70A. The plate 70A shown in Fig. 6 is attached to four magnets 5 (i.e., a first radial magnet 1, a second radial magnet 2, a first circumferential magnet 3, and a second circumferential magnet 4) that are arranged in a Halbach array, thereby integrating the four magnets 5.

[0053] The advantages of having the stator 20 equipped with the plate 70A are explained below. The angle between the protrusion direction of the protrusions 50 and the horizontal direction tends to vary among the multiple protrusions 50. The smaller the angle between the protrusion direction and the horizontal direction, the greater the radially outward force acting from the protrusions 50 on the magnets 5. The greater this force, the greater the contribution to preventing the magnets 5 from falling off.

[0054] To explain a specific example with reference to Figure 6, of the five protrusions 50 that abut against any of the four magnets 5 integrated by the attachment of plate 70A, the angle between the protruding direction and the horizontal direction of the protrusion 50 located on the other circumferential side of the second radial magnet 2 is the smallest. The radially outward force Tr acting on the magnet 5 from this protrusion 50 is greater than the radially outward forces (not shown) acting from the other four protrusions 50, and contributes greatly to preventing the magnet 5 from falling off (suppressing falling off).

[0055] According to the configuration in which the stator 20 includes the plate 70A (70), the four magnets 5 are integrated by the plate 70A, so the protrusions 50 in Fig. 6 that generate the force Tr can significantly contribute to preventing the detachment of not only the second radial magnet 2 but also the other three magnets 5. This realizes a stator 20 that can further prevent the detachment of multiple magnets 5. The protrusion direction of the protrusions 50 is parallel to the radial direction.

[0056] By using the same principle, the above advantages can 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 constituting stator 20 are integrated by the attachment of plate 70B, which prevents the magnets 5 from falling off.

[0057] Furthermore, with 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 a plurality of magnets 5, including the first radial magnet 1 and the second radial magnet 2, which are two magnets 5 with a relatively high risk of falling off, so that the plurality of magnets 5 can be more reliably prevented from falling off.

[0058] 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.

[0059] <Method of Assembling Stator 20> A method of assembling the stator 20 will be described with reference to FIGS. 6 to 9. In the following description, "step" may be abbreviated as "S." FIG. 7 is a flowchart of a method of assembling the stator 20 according to an embodiment of the present disclosure. FIG. 8 is a schematic diagram showing a radial magnet placement step (S11) according to an embodiment of the present disclosure. FIG. 9 is a schematic diagram showing a circumferential magnet placement step (S13) according to an embodiment of the present disclosure. Assembly 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. 9).

[0060] First, a radial magnet placement step (S11) is performed to place the first radial magnet 1 and the second radial magnet 2 between any two protrusions 50 that are consecutively arranged in the circumferential direction. As shown in FIG. 8 , the first radial magnet 1 and the second radial magnet 2 are each moved from the inside to the outside in the radial direction to a predetermined assembly position where they are sandwiched between the two protrusions 50. In the example of FIG. 8 , when the first radial magnet 1 moves, the two protrusion abutment surfaces 8 slide against the second end face 52 of the protrusion 50 on one side and the first end face 51 of the protrusion 50 on the other side, respectively. The first radial magnet 1 then reaches the predetermined assembly position. Similarly, when the second radial magnet 2 moves, the two protrusion abutment surfaces 8 slide against the first end face 51 and the second end face 52, respectively, and the second radial magnet 2 then reaches the predetermined assembly position.

[0061] During execution of S11, the first radial magnet 1 and the second radial magnet 2, which have reached their assembly positions, 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 protrusions 50 is configured to be half or less of the radial length of the magnet 5, the bending moment generated in the protrusions 50 can be reduced, making it possible to prevent damage to the protrusions 50.

[0062] 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.

[0063] 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.

[0064] Next, a circumferential magnet arrangement step (S13) is performed in which the first circumferential magnet 3 and the second circumferential magnet 4 are arranged between the other two protrusions 50 that are consecutively arranged in the circumferential direction. As shown in Figure 9, the first circumferential magnet 3 and the second circumferential magnet 4 are each moved from the inside to the outside in the radial direction to a predetermined assembly position where they are sandwiched between the two protrusions 50. The details are the same as in S11.

[0065] Next, an intervening member disposing step (S15) is performed in which an intervening member 90 is disposed between two circumferentially adjacent magnets 5. For example, in S15, the intervening member 90 as an adhesive is filled into the space formed between the two adjacent magnets 5, and then a curing process such as a heat treatment is performed. In this way, the intervening member 90 is disposed (see FIG. 6 ).

[0066] Next, a plate placement step (S17) is performed in which plate 70A (70) is placed on inner circumferential surfaces 15 of two or more consecutively arranged magnets 5. Plate 70A is attached to inner circumferential surfaces 15, for example, via adhesive (not shown). This completes the assembly method for stator 20 (see FIG. 6).

[0067] <Another embodiment (first example)> Fig. 10 is a schematic diagram showing a stator 20A according to another embodiment. The stator 20A includes a cylindrical body 99 fitted onto the inner circumferential surfaces of a plurality of tip portions 252, and the above-mentioned plurality of protrusions 53 (50) are integrally formed with the cylindrical body 99. The cylindrical body 99 is made of, for example, a non-magnetic material. More specifically, the cylindrical body 99 is formed of CFRP or GFRP.

[0068] The plurality of protrusions 50 protrude radially inward from the cylindrical body 99. The protrusion 50 illustrated in Fig. 10 is formed integrally with the cylindrical body 99 and protrudes radially inward beyond the plurality of teeth 25. The plurality of protrusions 50 are connected to the plurality of teeth 25 via the cylindrical body 99.

[0069] Furthermore, no intervening members 90 (see FIG. 3 ) are disposed between the multiple magnets 5 that make up the stator 20A. Therefore, the first abutment inclined end surfaces 49 of each of the first circumferential magnets 3 and the second circumferential magnets 4 directly abut against the first inclined end surfaces 61 of the first radial magnets 1. Even in this case, the force acting from the first abutment inclined end surfaces 49 to the first inclined end surfaces 61 includes a force directed radially outward. The application of this force prevents the first radial magnets 1 from coming off the teeth 25.

[0070] Furthermore, the second inclined end face 62 of the second radial magnet 2 also directly abuts against the second inclined contact end face 48 of the second circumferential magnet 4. Even in this case, the force acting from the second inclined contact end face 48 to the second inclined end face 62 includes a force directed radially outward. The action of this force can prevent the second radial magnet 2 from coming off the teeth 25.

[0071] The stator 20A may further include the above-described plate 70. Although the plate 70A is shown in Fig. 10, the stator 20A may also include plates 70B and 70C.

[0072] <Another embodiment (second example)> The radial magnet placement step (S11 in FIG. 7) according to another embodiment will be described with reference to Figure 11. After the first radial magnet 1 is placed between the two protrusions 50 in S11, a step of bending the two protrusions 50 toward the center C1 of the first radial magnet 1 may be performed. In this case, as an example, the magnet 5 moving from the inside to the outside in the radial direction may not slide relative to the protrusions 50.

[0073] The shape of the protrusions 50 after this step is performed (i.e., the shape of the protrusions 50 in the lower part of Figure 11) will be described. In the following description, the pair of protrusions 50 that sandwich the first radial magnet 1 in the circumferential direction may be referred to as a pair of first protrusions 55.

[0074] Each first protrusion 55 includes a first base-side extending portion 551, a first tip-side extending portion 552 located radially inward of the first base-side extending portion 551, and a first bent portion 553 connected to the first base-side extending portion 551 and the first tip-side extending portion 552. The first base-side extending portion 551 and the first tip-side extending portion 552 extend radially, and the first bent portion 553 bends toward the center C1 of the first radial magnet 1 as it moves radially inward. At least one of the pair of first tip-side extending portions 552 abuts against a first inclined end surface 61 of the first radial magnet 1. In the example of FIG. 11 , a first inclined end surface 61 is formed on each of the one end face 11 and the other end face 111 of the first radial magnet 1, and the pair of first tip-side extending portions 552 abut against the pair of first inclined end surfaces 61, respectively. In this example, the first base end extension portion 551 faces the first radial magnet 1 in the circumferential direction with a gap M1 therebetween.

[0075] According to the above configuration, the provision of the first bent portion 553 reduces the angle (acute angle) between the first tip-side extending portion 552 and the radial direction, allowing the pair of first tip-side extending portions 552 to firmly sandwich the first radial magnet 1. This prevents the first radial magnet 1 from falling off. Furthermore, before the bending process to form the first bent portion 553 is performed, the circumferential distance between the two protrusions 50 is relatively long. In this example, the first radial magnet 1 can be moved (inserted) between the two protrusions 50 before the bending process is performed, thereby facilitating the step (S11) of arranging the first radial magnet 1. At least one of the first end face 51 or the second end face 52, which are both circumferential end faces of each first protrusion 55 (protrusion 50), may be inclined radially so as to move radially inward toward the center of the first protrusion 55. In this case, the step (S11) of moving the first radial magnet 1 to between the two first protrusions 55 before bending is further facilitated. Furthermore, the radially inner end surface of each first protrusion 55 may be a curved surface that is convex toward the inside in the radial direction. Even in this case, the first radial magnet 1 moving toward between the two protrusions 50 is prevented from being obstructed by the radially inner end surface of the first protrusions 55, so the step (S11) of arranging the first radial magnet 1 can be further facilitated.

[0076] The configuration of the first protrusions 55 described above may be applied to a pair of protrusions 50 that circumferentially sandwich the second radial magnet 2 shown in Fig. 12. In the following description, the pair of protrusions 50 that circumferentially sandwich the second radial magnet 2 may be referred to as a pair of second protrusions 56.

[0077] Each second protrusion 56 includes a second base-side extending portion 561, a second tip-side extending portion 562 located radially inward of the second base-side extending portion 561, and a second bent portion 563 connected to the second base-side extending portion 561 and the second tip-side extending portion 562. The second base-side extending portion 561 and the second tip-side extending portion 562 extend radially, and the second bent portion 563 bends toward the center C2 of the second radial magnet 2 as it moves radially inward. At least one of the pair of second tip-side extending portions 562 abuts against the second inclined end surfaces 62 of the second radial magnet 2. In the example of FIG. 12 , the second inclined end surfaces 62 are formed on each of the one end surface 22 and the other end surface 222 of the second radial magnet 2, and the pair of second tip-side extending portions 562 abut against the pair of second inclined end surfaces 62, respectively. In addition, the second base end side extending portion 561 in this example faces the second radial magnet 2 in the circumferential direction with a gap M2 therebetween.

[0078] According to the above configuration, the pair of second tip-side extending portions 562 can firmly hold the second radial magnet 2 therebetween, and the second radial magnet 2 can be prevented from falling off.

[0079] The radial length of at least one of the first protrusions 55 and the second protrusions 56 may be less than half the radial length of the magnet 5. Also, an intervening member 90 (see FIG. 6) may be disposed between the magnet 5 and the protrusions 50 (i.e., the first protrusions 55 and the second protrusions 56) shown in Figures 11 and 12, or a plate 70 (see FIG. 6) may be disposed on the magnet 5 shown in the same figures. The advantages obtained by employing at least one of these configurations have already been described, so detailed explanation will be omitted.

[0080] <Another embodiment (third example)> A stator 20B according to another embodiment will be described with reference to Fig. 13. The stator 20B includes pressing members 80. The number of pressing members 80 in this example is the same as the number of magnets 5 that constitute the stator 20.

[0081] Each magnet 5 constituting the stator 20B 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.

[0082] The permanent magnet 12 includes a first permanent magnet 121 located closest to the first side in the axial direction and a second permanent magnet 122 located closest to the second side opposite the first side, 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.

[0083] The stator 20B 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.

[0084] 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.

[0085] 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.

[0086] 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. 10 ).

[0087] According to a configuration in which the stator 20B includes the 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.

[0088] Furthermore, when the pressing member 80 is configured as a wire 89 that binds the first reel 91, the second reel 92, and each of the plurality of permanent magnets 12, the tension of the wire 89 generated by winding the wire 89 around at least one of the first reel 91 and the second reel 92 causes the second axially extending portion 84 to press each of the plurality of permanent magnets 12 radially outward. This prevents at least one of the plurality of permanent magnets 12 constituting each magnet 5 from falling off. The stator 20B may also include the plate 70 described above. In this case, the first axially extending portion 83 described above may be disposed in a groove formed on the inner surface of the plate 70. The first reel 91 and the second reel 92 may also be provided on the teeth 25. In this case, the second axially extending portion 84 extends axially radially outward of the tip portion 252 (see FIG. 2 ). The above advantages are achieved in any of the embodiments.

[0089] <Another embodiment (fourth example)> A stator 20C (20) according to another embodiment will be described with reference to Fig. 14. More specifically, the shapes of the first circumferential magnets 3 and the second circumferential magnets 4 constituting the stator 20C will be described.

[0090] The other end surface 333 of the first circumferential magnet 3 and the one end surface 44 of the second circumferential magnet 4 both have a first abutting inclined end surface 49. The other end surface 333 and the one end surface 44 each further have a first extending surface 131 and a first connecting surface 141. The first extending surface 131 extends radially from the outer side to the inner side along the protrusion 53 (50) radially outward from the first abutting inclined end surface 49. The first extending surface 131 directly abuts the protrusion 53. The first connecting surface 141 extends along the circumferential direction radially inward from the protrusion 53 (50). The first connecting surface 141 may extend parallel to the circumferential direction, or may extend at an angle relative to the circumferential direction as shown. Furthermore, the first connecting surface 141 connects to the radially inner end 131 a of the first extending surface 131 and the radially outer end 49 a of the first abutting inclined end surface 49. At least a part of the circumferential range in which the first connecting surface 141 is arranged is included in the circumferential range in which the protrusion 53 (50) that abuts against the first extending surface 131 is arranged.

[0091] 14 , an intervening member 90 is interposed between the other end face 333 of the first circumferential magnet 3 and the first inclined end face 61 of the first radial magnet 1, and between the one end face 44 of the second circumferential magnet 4 and the first inclined end face 61 of the first radial magnet 1, but the present disclosure is not limited to this. For example, the other end face 333 may directly abut the first inclined end face 61, or the one end face 44 may directly abut the first inclined end face 61. Furthermore, either the other end face 333 of the first circumferential magnet 3 or the one end face 44 of the second circumferential magnet 4 may not have the first abutting inclined end face 49, the first extending surface 131, or the first connecting surface 141. Furthermore, at least one of the one end face 33 of the first circumferential magnet 3 or the other end face 444 of the second circumferential magnet 4 may have a first abutting inclined end face 49, a first extending surface 131, and a first connecting surface 141.

[0092] According to the above configuration, the first connecting surface 141 is interposed between the first abutting inclined end surface 49 and the first extending surface 131, so that at least one of the other end surface 333 of the first circumferential magnet 3 and the one end surface 44 of the second circumferential magnet 4 is raised in the circumferential direction. This makes it possible to increase the amount of magnet in the same space of at least one of the first circumferential magnet 3 and the second circumferential magnet 4.

[0093] <Another embodiment (fifth example)> A stator 20D according to another embodiment will be described with reference to Fig. 15. More specifically, the shape of the first radial magnets 1 constituting the stator 20D will be described.

[0094] Both the first end face 51 and the second end face 52 have a first inclined end face 61. Each of the first end face 51 and the second end face 52 further has a second extension surface 132 and a second connecting surface 142. The second extension surface 132 extends radially from the outer side to the inner side along the protrusion 53 (50) radially outward from the first inclined end face 61. The second extension surface 132 directly abuts the protrusion 53. The second connecting surface 142 extends circumferentially radially inward from the protrusion 53 (50). The second connecting surface 142 may extend parallel to the circumferential direction or may extend at an angle relative to the circumferential direction as shown. Furthermore, the second connecting surface 142 connects the radially inner end 132a of the second extension surface 132 and the radially outer end 61a of the first inclined end face 61. At least a portion of the circumferential range in which the second connecting surface 142 is disposed is included in the circumferential range in which the protrusion 53 (50) that abuts against the second extending surface 132 is disposed.

[0095] 15 , intervening members 90 are interposed between the first radial magnet 1 and the first circumferential magnet 3, and between the first radial magnet 1 and the second circumferential magnet 4, but the present disclosure is not limited to this. For example, the two first inclined end faces 61 may directly abut the first circumferential magnet 3 and the second circumferential magnet 4, respectively. Furthermore, either the first end face 51 or the second end face 52 may not have the first inclined end face 61, the second extension surface 132, and the second connecting surface 142.

[0096] According to the above configuration, the second connecting surface 142 is interposed between the first inclined end surface 61 and the second extending surface 132, so that at least one of the first end surface 51 and the second end surface 52 is raised in the circumferential direction. This increases the amount of magnet in the same space of the first radial magnet 1.

[0097] It is also possible to apply both the other embodiment according to the fourth example and the other embodiment according to the fifth example to the stator 20. For example, when only one end face 33 of the one end face 33 or the other end face 333 of the first circumferential magnet 3 has the first abutment inclined end face 49, the first extension surface 131, and the first connecting surface 141, only the first end face 51 of the first end face 51 or the second end face 52 of the first radial magnet 1 may have the first inclined end face 61, the second extension surface 132, and the second connecting surface 142.

[0098] <Other Embodiments (Sixth 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.

[0099] <Summary> The contents described in the above-described embodiments can be understood, for example, as follows.

[0100] 1) A stator (20, 20A, 20B, 20C, 20D) according to one embodiment of the present disclosure is a stator comprising: a stator core (24) including a plurality of teeth (25) arranged at intervals in a circumferential direction based on an axis (S); and a plurality of magnets (5) including a magnet group (e.g., four magnets 5 arranged continuously in the circumferential direction) arranged radially inward of the plurality of teeth in the circumferential direction, the magnet group being arranged in a Halbach array, wherein the magnet group includes: a first radial magnet (1) magnetized on the radially outer side; a first circumferential magnet (3) located on one side of the first radial magnet in the circumferential direction and magnetized to the one side; and a second circumferential magnet (4) located on the other side of the circumferential direction of the first radial magnet and magnetized to the other side. At least one of the one end face (11) or the other end face (111) in the circumferential direction of the first radial magnet has a first inclined end face (61) that inclines toward the circumferential center (C1) of the first radial magnet as it moves inward in the radial direction, and at least one of the other end face (333) in the circumferential direction of the first circumferential magnet or the one end face (44) in the circumferential direction of the second circumferential magnet has a first abutting inclined end face (49) that inclines toward the circumferential center of the first radial magnet as it moves inward in the radial direction and abuts against the first inclined end face.

[0101] According to the configuration of 1), the first inclined contact end surface directly or indirectly contacts the first inclined end surface, and a radially outward force acts on the first radial magnet. This prevents the first radial magnet from coming off the multiple teeth. This realizes a stator that can prevent at least one of the multiple magnets from falling off.

[0102] 2) In some embodiments, the stator described in 1) above, wherein the one end face and the other end face of the first radial magnet each have the first inclined end face, and the other end face of the first circumferential magnet and the one end face of the second circumferential magnet each have the first abutting inclined end face.

[0103] According to the configuration of 2), a force directed radially outward is generated at each of the one end face and the other end face of the first radial magnet, which further prevents the first radial magnet from coming off the multiple teeth.

[0104] 3) In some embodiments, the stator is the one described in 1) or 2) above, wherein the magnet group further includes a second radial magnet (2) located on the other side of the second circumferential magnet in the circumferential direction and magnetized radially inward, one end face (22) of the second radial magnet in the circumferential direction has a second inclined end face (62) that inclines toward a center (C2) of the second radial magnet in the circumferential direction as it moves toward the radially inward, and the other end face (444) of the second circumferential magnet has a second abutting inclined end face (48) that inclines toward the center of the second radial magnet as it moves radially inward and abuts against the second inclined end face.

[0105] According to the configuration of 3), the second inclined contact end surface directly or indirectly contacts the second inclined end surface, and a radially outward force acts on the second radial magnet. This prevents the second radial magnet from coming off the multiple teeth. This realizes a stator that prevents the multiple magnets from falling off.

[0106] 4) In some embodiments, the stator is the one described in any one of 1) to 3) above, further comprising a plurality of protrusions (50) that protrude radially inward beyond the plurality of teeth and are arranged alternately with the plurality of magnets in the circumferential direction, two of the plurality of protrusions that are adjacent in the circumferential direction sandwich any one of the plurality of magnets in the circumferential direction, and the radial length of each of the plurality of protrusions is equal to or less than half the radial length of each of the plurality of magnets.

[0107] According to the configuration of 4) above, the radial length of each of the multiple protrusions can be shortened. This allows each of the multiple magnets to be moved from the radially inner side to a predetermined assembly position where it is sandwiched between two protrusions during the stator assembly process. Conventionally, it was necessary to slide the magnet axially to a predetermined assembly position where it is sandwiched between two fingers. However, because the fingers and magnets generally have a shape that extends axially, the magnet slides a long distance, which poses a problem of laborious assembly of the magnet. In this regard, according to the configuration above, each magnet is moved radially, thereby reducing the amount of magnet movement and improving stator assembly.

[0108] 5) In some embodiments, the stator is as described in 4) above, wherein a first end face (51) and a second end face (52) in the circumferential direction of each of the plurality of protrusions both extend in the radial direction.

[0109] According to the configuration of 5) above, the protrusions have a shape in which the circumferential length becomes shorter as they move radially inward, which makes it easier to move the magnets from the radially outer side to the predetermined assembly position. This further simplifies the magnet assembly process.

[0110] 6) In some embodiments, the stator is as described in 4) or 5) above, wherein one end face (6) and the other end face (7) in the circumferential direction of each of the plurality of magnets are both located radially outward of the first inclined end face and the first abutment inclined end face and have a protrusion abutment surface (8) that abuts against the protrusion, and the protrusion abutment surface extends in the radial direction.

[0111] According to the configuration of 6) above, the projection abutment surface extends radially, thereby widening the radial range in which the projection abutment surface and the projection abut. As a result, even if the radial length of the projection is short, each magnet is firmly sandwiched between the two projections. This achieves a stator that prevents multiple magnets from falling off. Furthermore, even if at least one of the first circumferential magnet and the second circumferential magnet has a first abutment inclined end surface, the projection abutment surface extends radially, making it easy to move the circumferential magnet to the predetermined assembly position where it is sandwiched between the two projections, further simplifying the stator assembly process.

[0112] 7) In some embodiments, in the stator described in 6) above, the radial length of each of the projection abutment surfaces is equal to or less than half the radial length of each of the plurality of magnets.

[0113] According to the configuration 7) above, the distance that the projection abutment surface slides over relative to the projection during the magnet assembly process can be shortened, further simplifying the stator assembly process.

[0114] 8) In some embodiments, the stator is the one described in any one of 1) to 3) above, further comprising a plurality of protrusions (50) that protrude radially inward beyond the plurality of teeth and are arranged alternately with the plurality of magnets in the circumferential direction, two of the plurality of protrusions that are adjacent in the circumferential direction sandwich one of the plurality of magnets in the circumferential direction, the plurality of protrusions include a pair of first protrusions (55) that sandwich the first radial magnet, and each of the pair of first protrusions has a first bent portion (553) that bends toward the center (C1) of the first radial magnet.

[0115] According to the configuration of 8) above, the pair of first protrusions can more firmly sandwich the first radial magnet. This makes it possible to prevent the first radial magnet from falling off. Furthermore, the circumferential distance between the two protrusions before the bending process to form the first bent portion is relatively long. According to the configuration of 8) above, the first radial magnet can be moved (inserted) between the two protrusions before the bending process is performed, which simplifies the process of arranging the first radial magnet 1.

[0116] 9) In some embodiments, the stator is the one described in any one of 4) to 8) above, further comprising a plurality of intervening members (90) arranged radially inward of the plurality of protrusions, each intervening member being sandwiched between two of the plurality of magnets that are adjacent to each other in the circumferential direction.

[0117] According to the configuration of 9) above, since an intervening member is interposed between two adjacent magnets, dispersion of the force transmitted from one of the two adjacent magnets to the other can be suppressed. As a more specific example, the first abutment inclined end surface can be in stable surface contact with the first inclined end surface via the intervening member, suppressing dispersion of the force exerted from the first abutment inclined end surface to the first inclined end surface. This increases the radial force acting on the first radial magnet, suppressing disengagement of the first radial magnet from the multiple teeth. This realizes a stator that further suppresses disengagement of the multiple magnets.

[0118] 10) In some embodiments, the stator according to any one of 4) to 9) above further comprises a plate (70) extending in the circumferential direction and attached to the inner circumferential surface (15) of each of the two or more magnets, including the first radial magnet.

[0119] The angle between the protrusion direction and the horizontal direction tends to vary among multiple protrusions. The smaller the angle between the protrusion direction and the horizontal direction, the greater the radial force acting from the protrusion on the magnet, making it less likely for the magnet to fall off. In this regard, with the configuration of 10) above, the protrusion with the smallest angle among three or more protrusions that contact two or more magnets integrated by a plate contributes significantly to preventing the two or more integrated magnets from falling off. This achieves a stator that can further prevent multiple magnets from falling off.

[0120] 11) In some embodiments, the stator is as described in 10) above, wherein the magnet group further includes a second radial magnet (2) located on the other side of the circumferential direction relative to the second circumferential magnet and magnetized radially inward, and the magnets to which the plate is attached include the first radial magnet and the second radial magnet.

[0121] According to the configuration of 11) 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 the multiple magnets can be more reliably prevented.

[0122] 12) In some embodiments, the stator is described in either 10) or 11) 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.

[0123] According to the above configuration 12), all the magnets are integrated by the plate, and the magnets are prevented from falling off.

[0124] 13) In some embodiments, the stator is as described in any one of 10) to 12) 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.

[0125] According to the configuration of 13), it is possible to attach the second plate part to the place where the temperature rises slowly and the first plate part to the place where the temperature rises rapidly, which makes it possible to prevent the integrated magnet from falling off and also to prevent damage to the plate due to thermal deformation.

[0126] 14) In some embodiments, the stator is described in any one of 1) to 13) above, wherein the first radial magnet includes a plurality of permanent magnets (12) stacked in the axial direction, and the stator further includes a pressing member (80) that presses the inner circumferential surface of each permanent magnet outward in the radial direction.

[0127] According to the configuration of 14) 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.

[0128] 15) In some embodiments, the stator is the one described in 14) above, wherein the plurality of permanent magnets include a first permanent magnet (121) located at the first side in the axial direction, and a second permanent magnet (122) 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 (121B) of the second permanent magnet facing the second side, and the pressing member is a wire (89) that binds together the first reel, the second reel, and each of the plurality of permanent magnets.

[0129] According to the configuration of 15), the tension generated by winding the wire around at least one of the first reel and the second reel presses the permanent magnets radially outward, thereby preventing at least one of the permanent magnets constituting the magnet from falling off.

[0130] 16) In some embodiments, the stator described in any one of 1) to 15) above further comprises a plurality of protrusions (50) that protrude radially inward beyond the plurality of teeth and are arranged alternately with the plurality of magnets in the circumferential direction, and two of the plurality of protrusions that are adjacent in the circumferential direction sandwich one of the plurality of magnets in the circumferential direction, and at least one of the other end face in the circumferential direction of the first circumferential magnet or the one end face in the circumferential direction of the second circumferential magnet has: a first extending surface (131) that extends along the protrusions radially outward from the first abutting inclined end face, and a first connecting surface (141) that extends along the circumferential direction radially inward from the protrusions and connects to the radially inner end of the first extending surface and the radially outer end of the first abutting inclined end face.

[0131] According to the configuration of 16), since the first connecting surface is interposed between the first inclined end surface and the first extending surface, at least one of the other end surface of the first circumferential magnet and one end surface of the second circumferential magnet is raised in the circumferential direction, thereby increasing the amount of magnet in the same space of at least one of the first circumferential magnet and the second circumferential magnet.

[0132] 17) In some embodiments, the stator described in any one of 1) to 16) above further comprises a plurality of protrusions (50) that protrude radially inward beyond the plurality of teeth and are arranged alternately with the plurality of magnets in the circumferential direction, and two of the plurality of protrusions that are adjacent in the circumferential direction sandwich one of the plurality of magnets in the circumferential direction, and at least one of the one end face or the other end face in the circumferential direction of the first radial magnet has: a second extension surface (132) that extends along the protrusions radially outward from the first inclined end face; and a second connection surface (142) that extends along the circumferential direction radially inward from the protrusions and connects the radially inner end of the second extension surface and the radially outer end of the first inclined end face.

[0133] According to the configuration of 17), since the second connecting surface is interposed between the first inclined end surface and the second extending surface, at least one of the first end surface and the second end surface is raised in the circumferential direction, thereby increasing the amount of magnet in the same space of the first radial magnet.

[0134] 18) A magnetic gear electric machine (10) according to at least one embodiment of the present disclosure comprises: a stator (20, 20A, 20B) according to any one of 1) to 13) above; a pole piece rotor (30) including a plurality of pole pieces (36) arranged in the circumferential direction and radially inward of the stator; and a magnet rotor (40) including an inner magnet (41) arranged radially inward of the plurality of pole pieces.

[0135] According to the configuration of 18) above, the same effects as those of 1) above can be obtained.

[0136] 19) A method for assembling a stator (20, 20A, 20B, 20C, 20D) according to at least one embodiment of the present disclosure, is a manufacturing method of a stator including: a stator core (24) including a plurality of teeth (25) arranged at intervals in a circumferential direction based on an axis (S); a plurality of magnets (5) including a magnet group (e.g., four magnets 5 arranged continuously in the circumferential direction) arranged radially inward of the plurality of teeth, the magnet group being arranged in a Halbach array; and a plurality of protrusions (50) that protrude radially inward beyond the plurality of teeth and are arranged alternately with the plurality of magnets in the circumferential direction, wherein the magnet group includes: a first radial magnet (1) magnetized on the outside in the radial direction; a first circumferential magnet (3) located on one side of the first radial magnet in the circumferential direction and magnetized to the one side; and a second circumferential magnet (4) located on the other side of the first radial magnet in the circumferential direction and magnetized to the other side. At least one of one end face (11) or the other end face (111) in the circumferential direction of the first radial magnet has a first inclined end face (61) that inclines toward the center (C1) of the circumferential direction of the first radial magnet as it moves toward the inside in the radial direction, and at least one of the other end face (333) in the circumferential direction of the first circumferential magnet or one end face (44) in the circumferential direction of the second circumferential magnet has a first abutting inclined end face (49) that inclines toward the center in the circumferential direction of the first radial magnet as it moves toward the inside in the radial direction and abuts against the first inclined end face, The assembling method of the stator includes the steps of: arranging the first radial magnet and the second radial magnet between any two of the protrusions that are lined up consecutively in the circumferential direction; After the step of arranging the first radial magnet is performed, the method includes a step (S13) of arranging the first circumferential magnet and the second circumferential magnet between two other protrusions that are aligned consecutively in the circumferential direction.

[0137] According to the configuration of 19) above, the same effects as those of 1) above can be obtained.

[0138] 1: First radial magnet 2: Second radial magnet 3: First circumferential magnet 4: Second circumferential magnet 5: Magnet 6, 11, 22, 33, 44: One end face 7, 111, 222, 333, 444: Other end face 8: Projection abutment surface 10: Magnetic gear electric machine 12: Permanent magnet 15: Inner peripheral surface 20, 20A, 20B, 20C, 20D: Stator 24: Stator core 25: Teeth 30: Pole piece rotor 36: Pole piece 40: Magnet rotor 41: Inner magnet 48: Second abutment inclined end face 49: First abutment inclined end face 50, 53, 54: Projection 51: First end face 52: Second end face 55 : First protrusion 56 : Second protrusion 61 : First inclined end surface 62 : Second inclined end surface 70, 70A, 70B, 70C : Plate 71 : First plate portion 72 : Second plate portion 80 : Pressing member 81 : First winding portion 82 : Second winding portion 83 : First axially extending portion 84 : Second axially extending portion 85 : Bent portion 89 : Wire 90 : Intervening member 91 : First reel 92 : Second reel 99 : Cylinder 111 : Other end surface 121 : First permanent magnet 121A : First surface 122 : Second permanent magnet 122A : Second surface 201 : Slot opening 209 : Holding member 251 : Protrusion 252 : Tip part 551 : First base side extension part 552 : First tip side extension part 553 : First bent part 561 : Second base side extension part 562 : Second tip side extension part 563 : Second bend part C1 : Center C2 : Center S : Axis center

Claims

1. A stator comprising: a stator core including a plurality of teeth arranged at intervals in a circumferential direction based on an axis; and a plurality of magnets including a magnet group arranged continuously in the circumferential direction radially inward of the plurality of teeth, the magnets being arranged in a Halbach array, wherein the magnet group includes: a first radial magnet magnetized on the outer side in the radial direction; a first circumferential magnet located on one side in the circumferential direction of the first radial magnet and magnetized on the one side; and a second circumferential magnet located on the other side in the circumferential direction of the first radial magnet and magnetized on the other side, wherein at least one of one end face or the other end face in the circumferential direction of the first radial magnet has a first inclined end face that inclines toward the center of the circumferential direction of the first radial magnet as it moves toward the inside in the radial direction, At least one of the other end face in the circumferential direction of the first circumferential magnet and one end face in the circumferential direction of the second circumferential magnet has a first abutment inclined end face that inclines toward the center in the circumferential direction of the first radial magnet as it moves toward the inside in the radial direction and abuts against the first inclined end face.

2. A stator as set forth in claim 1, wherein said one end face and said other end face of said first radial magnet each have said first inclined end face, and said other end face of said first circumferential magnet and said one end face of said second circumferential magnet each have said first abutting inclined end face.

3. A stator as described in claim 1 or 2, wherein the magnet group further includes a second radial magnet located on the other side in the circumferential direction than the second circumferential magnet and magnetized radially inward, one end face in the circumferential direction of the second radial magnet has a second inclined end face that inclines toward the center of the second radial magnet in the circumferential direction as it moves toward the inside in the radial direction, and the other end face of the second circumferential magnet in the circumferential direction has a second abutting inclined end face that inclines toward the center of the second radial magnet as it moves toward the inside in the radial direction and abuts against the second inclined end face.

4. A stator as described in claim 1 or 2, further comprising a plurality of protrusions that protrude radially inward beyond the plurality of teeth and are arranged alternately with the plurality of magnets in the circumferential direction, wherein two of the plurality of protrusions that are adjacent in the circumferential direction sandwich one of the plurality of magnets in the circumferential direction, and the radial length of each of the plurality of protrusions is less than half the radial length of each of the plurality of magnets.

5. A stator according to claim 4, wherein a first end face and a second end face in the circumferential direction of each of the plurality of projections both extend in the radial direction.

6. A stator as described in claim 4, wherein one end face and the other end face in the circumferential direction of each of the plurality of magnets are each located radially outboard of the first inclined end face and the first abutment inclined end face, and have a protrusion abutment surface that abuts against the protrusion, and the protrusion abutment surface extends in the radial direction.

7. A stator as set forth in claim 6, wherein the radial length of each of said projection abutment surfaces is equal to or less than half the radial length of each of said plurality of magnets.

8. A stator as described in claim 1 or 2, further comprising a plurality of protrusions that protrude radially inward beyond the plurality of teeth and are arranged alternately with the plurality of magnets in the circumferential direction, wherein two of the plurality of protrusions that are adjacent in the circumferential direction sandwich one of the plurality of magnets in the circumferential direction, and the plurality of protrusions include a pair of first protrusions that sandwich the first radial magnet, and each of the pair of first protrusions has a first bent portion that is bent toward the center of the first radial magnet.

9. A stator as described in claim 4, further comprising a plurality of intervening members arranged radially inward of the plurality of protrusions, each intervening member being sandwiched between two of the plurality of magnets that are adjacent in the circumferential direction.

10. The stator of claim 4, further comprising a circumferentially extending plate attached to an inner circumferential surface of each of two or more of said magnets, including said first radial magnet.

11. A stator as described in claim 10, wherein the magnet group further includes a second radial magnet located on the other circumferential side of the second circumferential magnet and magnetized radially inward, and the magnets to which the plate is attached include the first radial magnet and the second radial magnet.

12. A stator as set forth in claim 10, 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.

13. 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.

14. A stator as claimed in claim 1 or 2, wherein the first radial magnet includes a plurality of permanent magnets stacked in the axial direction, and the stator further comprises a pressing member that presses the inner circumferential surface of each permanent magnet outward in the radial direction.

15. A stator as described in claim 14, 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.

16. A stator as claimed in claim 1 or 2, further comprising a plurality of protrusions which protrude radially inward beyond the plurality of teeth and are arranged alternately with the plurality of magnets in the circumferential direction, wherein two of the plurality of protrusions which are adjacent in the circumferential direction sandwich one of the plurality of magnets in the circumferential direction, and at least one of the other end face in the circumferential direction of the first circumferential magnet or the one end face in the circumferential direction of the second circumferential magnet has a first extending surface which extends along the protrusions radially outward from the first abutting inclined end face, and a first connecting surface which extends along the circumferential direction radially inward from the protrusions and which connects to an inner end in the radial direction of the first extending surface and an outer end in the radial direction of the first abutting inclined end face.

17. A stator as claimed in claim 1 or 2, further comprising a plurality of protrusions which protrude radially inward beyond the plurality of teeth and are arranged alternately with the plurality of magnets in the circumferential direction, wherein two of the plurality of protrusions which are adjacent in the circumferential direction sandwich one of the plurality of magnets in the circumferential direction, and at least one of the one end face or the other end face in the circumferential direction of the first radial magnet has: a second extending surface which extends along the protrusions radially outward from the first inclined end face, and a second connecting surface which extends along the circumferential direction radially inward from the protrusions and which connects to an inner end in the radial direction of the second extending surface and an outer end in the radial direction of the first inclined end face.

18. A magnetic gear electric machine comprising: a stator according to claim 1 or 2; 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.

19. A method for assembling a stator comprising: a stator core including a plurality of teeth arranged at intervals in a circumferential direction based on an axis; a plurality of magnets including a magnet group arranged continuously in the circumferential direction radially inward of the plurality of teeth, the magnet group being arranged in a Halbach array; and a plurality of protrusions that protrude toward the inside in the radial direction beyond the plurality of teeth and are arranged alternately with the plurality of magnets in the circumferential direction, wherein the magnet group includes: a first radial magnet magnetized on the outside in the radial direction; a first circumferential magnet located on one side in the circumferential direction of the first radial magnet and magnetized to the one side; and a second circumferential magnet located on the other side in the circumferential direction of the first radial magnet and magnetized to the other side, wherein at least one of one end face or the other end face in the circumferential direction of the first radial magnet has a first inclined end face that inclines toward the center of the circumferential direction of the first radial magnet as it moves toward the inside in the radial direction, At least one of the other end face in the circumferential direction of the first circumferential magnet or one end face in the circumferential direction of the second circumferential magnet has a first abutting inclined end face that inclines toward the center of the first radial magnet in the circumferential direction as it moves toward the inside in the radial direction and abuts against the first inclined end face, and a method for assembling a stator includes the steps of: arranging the first radial magnet between any two of the protrusions that are lined up continuously in the circumferential direction; and after performing the step of arranging the first radial magnet, arranging the first circumferential magnet and the second circumferential magnet between other two of the protrusions that are lined up continuously in the circumferential direction.

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