Rotor and motor

Abstract

This rotor has: a rotor core that has a cylindrical rotor yoke extending in the axial direction; and a plurality of magnets that are positioned in a predetermined order in the circumferential direction in a Halbach array on a first surface that is one of the inner peripheral surface and outer peripheral surface of the rotor yoke. The plurality of magnets are each rectangular when viewed in the axial direction and include: a plurality of main magnets magnetized in the radial direction; and a plurality of auxiliary magnets magnetized in the circumferential direction. The rotor core has a protrusion protruding in the radial direction. The protrusion is positioned between a pair of magnets in which at least one of the pair of magnets adjacent to each other in the circumferential direction is the auxiliary magnet, and is in contact with the pair of magnets in the circumferential direction.

Description

Rotor and motor

[0001] The present invention relates to a rotor and a motor. This application claims priority based on Japanese Patent Application No. 2024-206705 filed in Japan on November 27, 2024, and the content thereof is incorporated herein by reference.

[0002] A rotor having Halbach arrayed magnets is known. For example, in Patent Document 1, a rotor of a two-segment pseudo-Halbach motor is disclosed, which includes a plurality of magnets including radially magnetized main magnets and circumferentially magnetized auxiliary magnets arranged along the circumferential direction, and a back iron arranged on one side of the plurality of magnets so as to be in surface contact with one surface of the plurality of magnets.

[0003] Japanese Unexamined Patent Application Publication No. 2022-82518

[0004] In the Halbach array, circumferentially magnetized auxiliary magnets are arranged in the circumferential direction of the radially magnetized main magnets. In this array, since the magnetic flux of the auxiliary magnets flows into the main magnets, the amount of magnetic flux on the output side of the main magnets increases. As a result, by arranging the magnets of the rotor in a Halbach array, it becomes possible to form a stronger magnetic field on either the radially inner or outer side of the rotor than the other. However, in such a rotor with a Halbach array, if a gap occurs between the main magnet and the auxiliary magnet, magnetic flux leakage may occur due to the gap, and the effect of the Halbach array may not be fully exerted.

[0005] In the rotor disclosed in Patent Document 1, by making the shape of the magnet trapezoidal when viewed in the axial direction, the occurrence of a gap between a pair of adjacent magnets in the circumferential direction is prevented. However, high machining accuracy is required to arrange the magnets without gaps in the circumferential direction of the rotor. Therefore, in a rotor with a Halbach array using magnets rectangular when viewed in the axial direction, a configuration capable of achieving high torque has been demanded.

[0006] An object of the present invention is to provide a configuration capable of achieving high torque in a rotor having a Halbach array of magnets rectangular when viewed in the axial direction.

[0007] A rotor according to an exemplary embodiment of the present invention comprises a rotor core having a cylindrical rotor yoke extending in the axial direction, and a plurality of magnets positioned in a predetermined order in the circumferential direction by a Halbach arrangement on a first surface which is either the inner or outer circumferential surface of the rotor yoke. The plurality of magnets are each rectangular in shape when viewed in the axial direction and include a plurality of main magnets magnetized in the radial direction and a plurality of auxiliary magnets magnetized in the circumferential direction. The rotor core has a projection that protrudes radially. The projection is located between a pair of magnets where at least one of the circumferentially adjacent magnets is the auxiliary magnet, and is in circumferential contact with the pair of magnets.

[0008] A rotor according to an exemplary embodiment of the present invention comprises a rotor core having a cylindrical rotor yoke extending in the axial direction, and a plurality of magnets positioned in a predetermined order in the circumferential direction by a Halbach arrangement on a first surface, which is either the inner or outer circumferential surface of the rotor yoke. A retaining member is located on the second surface side, which is the other surface of the inner or outer circumferential surface of the rotor yoke, and holds the rotor core. The plurality of magnets are each rectangular in shape when viewed in the axial direction and include a plurality of main magnets magnetized in the radial direction and a plurality of auxiliary magnets magnetized in the circumferential direction. The retaining member has a cylindrical portion extending in the axial direction and in contact with the second surface of the rotor yoke. The rotor yoke has recesses on the second surface at positions radially aligned with the main magnets. The cylindrical portion has protrusions on the rotor yoke side that are inserted into the recesses.

[0009] A motor according to an exemplary embodiment of the present invention comprises a rotor and a stator radially opposed to the plurality of magnets of the rotor.

[0010] According to the present invention, a rotor in which rectangular magnets are arranged in a Halbach configuration when viewed in the axial direction can be provided that enables high torque.

[0011] Figure 1 is a cross-sectional view showing an example of the schematic configuration of a motor according to Embodiment 1. Figure 2 is a diagram showing the inside of the motor as viewed from the other axial direction. Figure 3 is a perspective view showing an example of the configuration of the rotor core and magnets according to Embodiment 1. Figure 4 is an enlarged view of the rotor as viewed in the axial direction. Figure 5 is a diagram schematically showing an example of the arrangement of multiple magnets when the magnets of the rotor are arranged in a Halbach array. Figure 6 is a cross-sectional view taken along line VI-VI in Figure 2. Figure 7 is a cross-sectional view taken along line VII-VII in Figure 2. Figure 8 is an enlarged perspective view of the retaining member as viewed from the radially inward direction. Figure 9 is a partially enlarged view of Figure 4. Figure 10 is an enlarged view of the rotor as viewed in the axial direction according to a modified example of Embodiment 1. Figure 11 is a perspective view showing an example of the configuration of the rotor and magnets according to Embodiment 2. Figure 12 is an enlarged perspective view of the retaining member as viewed from the radially inward direction. Figure 13 is an enlarged view of the rotor as viewed in the axial direction.

[0012] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. Note that identical or corresponding parts in the drawings are denoted by the same reference numerals, and their descriptions will not be repeated. Furthermore, the dimensions of the components in each drawing do not faithfully represent the actual dimensions of the components or their dimensional ratios.

[0013] In the following description, the direction in which the central axis P of the motor 100 extends is referred to as the "axial direction A". The circumferential direction centered on the central axis P is referred to as the "circumferential direction C", and the radial direction centered on the central axis P is referred to as the "radial direction R". In this specification, the direction extending linearly between two points that are at equal distances from the center when viewing the member in the axial direction is also referred to as the "circumferential direction".

[0014] Furthermore, the direction described as "one axial direction" in the specification is indicated as "A1" in the figure, and the direction described as "the other axial direction" is indicated as "A2" in the figure. Note that the directions shown in the figure are defined solely for explanatory purposes and do not limit the orientation of the motor during use or assembly according to the present invention.

[0015] Furthermore, in the following explanation, the expressions "fix," "connect," and "attach" (hereinafter referred to as "fixing, etc.") include not only cases where components are directly fixed to each other, but also cases where they are fixed to each other via other components. In other words, in the following explanation, the expressions "fixing, etc." include both direct and indirect fixing of components to each other.

[0016] (Embodiment 1) (Motor) Figure 1 is a cross-sectional view showing an example of the schematic configuration of the motor 100. Figure 2 is a view of the inside of the motor 100 from the other axial direction A2. As shown in Figures 1 and 2, the motor 100 has a fixed shaft 2, a stator 3, a rotor 4, and a plurality of bearings 5. The motor 100 is applied to, for example, an in-wheel motor that is placed in the drive wheel of an electric motorcycle. In this embodiment, the case in which the motor 100 is a so-called outer rotor type motor in which the rotor 4 is located radially R outward of the stator 3 will be described as an example.

[0017] The fixed shaft 2 is a hollow cylindrical shape extending in the axial direction A with respect to the central axis P. The stator 3 and multiple bearings 5 ​​are fixed to the outer surface of the fixed shaft 2.

[0018] The stator 3 is the armature of the motor 100. In this embodiment, the stator 3 has a stator core 31, a coil 32, and an insulator 33. The stator core 31 is a magnetic material. The stator core 31 is constructed, for example, by laminating electromagnetic steel sheets.

[0019] The stator core 31 has a cylindrical core back portion 311 and a plurality of teeth 312. In this embodiment, the core back portion 311 is located on the inner circumference side of the stator core 31. The plurality of teeth 312 extend radially outward from the core back portion 311 and are arranged in the circumferential direction C. The tips of the plurality of teeth 312 face the plurality of magnets 42. An insulating insulator 33 is attached to each of the plurality of teeth 312.

[0020] The coil 32 is wound around each of the teeth 312 to which an insulator 33 is attached. The insulator 33 insulates the coil 32 from the stator core 31. The coil 32 is electrically connected to an external device via lead wires.

[0021] When a drive current is supplied to the coil 32 from an external device, a radial magnetic flux is generated in the teeth 312. This generates a circumferential torque in the rotor 4, which has magnets 42, causing the rotor 4 to rotate around the central axis P.

[0022] In this embodiment, the rotor 4 is located radially outward R relative to the stator 3. The rotor 4 is rotatably supported on the fixed shaft 2 via a plurality of bearings 5. The rotor 4 rotates about its central axis P due to the circumferential torque generated by the supply of drive current to the stator 3.

[0023] (Rotor) The rotor 4 has a rotor core 41, a magnet 42, and a holding member 43. The rotor core 41 is annular in shape and extends in the axial direction A with respect to the central axis P. The magnet 42 is fixed on the inner circumferential surface of the rotor core 41. The magnet 42 faces the stator 3 in the radial direction R.

[0024] (Rotor Core) Figure 3 is a perspective view showing an example of the configuration of the rotor core 41 and magnet 42. Figure 4 is an enlarged view of the rotor 4 as seen in the axial direction A. In Figure 4, the core back portion 311 and teeth 312 of the stator 3 are shown by dashed lines.

[0025] The rotor core 41 is made of a magnetic material. The rotor core 41 has a rotor yoke 411 and a protruding portion 412 that protrudes radially from the rotor yoke 411.

[0026] The rotor yoke 411 is cylindrical in shape, extending axially A with respect to the central axis P. The rotor yoke 411 has a first surface 411a, which is the surface facing the stator 3 in the radial direction R, and a second surface 411b on the opposite side. In this embodiment, the stator 3 is located radially R inward of the rotor 4. Therefore, in this embodiment, the first surface 411a is the inner surface of the rotor yoke 411, and the second surface 411b is the outer surface of the rotor yoke 411.

[0027] Multiple magnets 42 are fixed to the first surface 411a of the rotor yoke 411.

[0028] The protrusion 412 projects radially inward R from the first surface 411a of the rotor yoke 411. The protrusion 412 is located between adjacent magnets 42 in the circumferential direction C. The axial length A of the rotor yoke 411 and the axial length A of the protrusion 412 are equivalent. The relationship between the protrusion 412 and the magnets 42 will be described later.

[0029] (Magnets) The magnets 42 are positioned on the first surface 411a of the rotor yoke 411 in a predetermined order in the circumferential direction C by a Halbach arrangement. A Halbach arrangement is a magnetic circuit that concentrates the magnetic field in a specific direction and suppresses the magnetic field in other directions by arranging the polarity of the magnets in a certain pattern. Figure 5 is a schematic diagram showing an example of the arrangement of multiple magnets M when the magnets M of the rotor are arranged in a Halbach arrangement. In Figure 5, the magnetization direction of the magnets M is indicated by arrows. When the magnets M are arranged as in Figure 5, a strong magnetic field is formed radially inward of the rotor.

[0030] As shown in Figure 4, the rotor 4 includes a magnet 42 comprising a plurality of main magnets 421 magnetized in the radial direction and a plurality of auxiliary magnets 422 magnetized in the circumferential direction. In Figure 4, the magnetization direction of the magnets 42 is indicated by solid arrows, and the flow of magnetic flux is indicated by dashed arrows. As indicated by the dashed arrows in Figure 4, a strong magnetic field is formed in the rotor 4 in the radial direction R where the stator 3 is located. This makes it possible to provide a rotor 4 that can achieve high torque.

[0031] As shown in Figure 3, the main magnet 421 and the auxiliary magnet 422 are each rectangular parallelepiped. That is, the main magnet 421 and the auxiliary magnet 422 each have six planar sections. The axial length A of the main magnet 421 and the auxiliary magnet 422 is the same. The auxiliary magnet 422 is smaller than the main magnet 421.

[0032] Figure 6 is a cross-sectional view taken along line VI-VI in Figure 2. Figure 7 is a cross-sectional view taken along line VII-VII in Figure 2. As described above, the stator 3 has a cylindrical core back portion 311 extending in the axial direction A, and a plurality of teeth 312 extending radially R from the core back portion 311, with their tips facing a plurality of magnets 42.

[0033] As shown in Figure 6, the rotor core 41 protrudes in one axial direction A1 and the other axial direction A2 relative to the plurality of magnets 42. That is, the axial side A1 of the rotor yoke 411 protrudes in the axial direction A more than the axial side A1 of the plurality of magnets 42, and the axial side A2 of the rotor yoke 411 protrudes in the axial direction A more than the axial side A2 of the plurality of magnets 42.

[0034] By making the axial end A of the rotor yoke 411 protrude in the axial direction A relative to the axial end A of the magnet 42, leakage of the magnetic flux of the magnet 42 in the direction opposite to the direction in which the stator 3 is located can be suppressed.

[0035] Furthermore, the multiple magnets 42 protrude in one axial direction A1 and the other axial direction A2 relative to the multiple teeth 312 of the stator 3. That is, the axial direction A1 side of the multiple magnets 42 protrudes in the axial direction A more than the axial direction A1 side of the multiple teeth 312, and the axial direction A2 side of the multiple magnets 42 protrudes in the axial direction A more than the axial direction A2 side of the multiple teeth 312.

[0036] By making the ends of the multiple magnets 42 in the axial direction A protrude in the axial direction A relative to the ends of the multiple teeth 312 in the axial direction A, the multiple teeth 312 can capture the magnetic flux of more magnets 42. This makes it possible to obtain a motor 100 with increased torque.

[0037] (Holding Member) The holding member 43 is a member that holds the rotor core 41. The holding member 43 is a non-magnetic material. The holding member 43 is, for example, a cast part made of aluminum, or a resin molded part made of resin. For example, the holding member 43 is integrally molded with the rotor core 41 by insert molding.

[0038] Figure 8 is an enlarged perspective view of the retaining member 43 as seen from the radial direction R inward. As shown in Figures 6 to 8, the retaining member 43 has a cylindrical portion 431, a one-sided retaining portion 432, and a other-sided retaining portion 433. The cylindrical portion 431, the one-sided retaining portion 432, and the other-sided retaining portion 433 are a single component.

[0039] The cylindrical portion 431 is cylindrical and is located on the second surface 411b side of the rotor yoke 411. In other words, in this embodiment, the cylindrical portion 431 is located on the outer circumference side of the rotor core 41. The cylindrical portion 431 is in contact with the second surface 411b of the rotor yoke 411.

[0040] The one-sided retaining portion 432 extends radially inward R from one axial A1 of the cylindrical portion 431. The one-sided retaining portion 432 is annular when viewed in the axial direction A. The one-sided retaining portion 432 is in contact with the end face of one axial A1 of the rotor core 41.

[0041] In this embodiment, the one-sided retaining portion 432 has a groove portion 432a that extends in the circumferential direction. As shown in Figures 6 and 7, one axial end A1 of the rotor core 41 is inserted into the groove portion 432a in the axial direction A. That is, the bottom of the groove portion 432a is located in the axial direction A1 relative to the axial end A1 of the rotor core 41. The side wall portion of the groove portion 432a is located radially R inward relative to the axial end A1 of the rotor core 41.

[0042] The other side retaining portion 433 extends radially inward R from the other axial A2 of the cylindrical portion 431. The other side retaining portion 433 is annular when viewed in the axial direction A. The other side retaining portion 433 is in contact with the end face of the other axial A2 of the rotor core 41. That is, the other side retaining portion 433 is located in the axial direction A2 relative to the end of the other axial A2 of the rotor core 41.

[0043] That is, the holding member 43 has an annular one-side holding portion 432 that extends from one axial end A1 of the cylindrical portion 431 in the radial direction R and contacts the end surface of the rotor yoke 411 on the one axial end A1, and an annular other-side holding portion 433 that extends from the other axial end A2 of the cylindrical portion 431 in the radial direction R and contacts the end surface of the rotor yoke 411 on the other axial end A2 when viewed in the axial direction A. The one-side holding portion 432 has a groove portion 432a that extends in the circumferential direction into which the end portion of the rotor yoke 411 in the axial direction A is inserted in the axial direction A.

[0044] The one-side holding portion 432 and the other-side holding portion 433 of the holding member 43 contact the end surface of the rotor yoke 411 on the one axial end A1 and the end surface of the rotor yoke 411 on the other axial end A2, respectively. Thereby, the rotor yoke 411 can be fixed to the holding member 43 in the axial direction A. Further, the end portion of the rotor yoke 411 on the one axial end A1 is inserted into the groove portion 432a of the one-side holding portion 432. Thereby, the end portion of the rotor yoke 411 on the one axial end A1 can be fixed to the holding member 43 in the radial direction R. Therefore, a rotor 4 capable of achieving a high torque can be provided in a configuration in which the rotor yoke 411 can be fixed to the holding member 43 in the axial and radial directions.

[0045] (Details of the magnet and the protruding portion) As shown in FIG. 4, the magnets 42 are each rectangular when viewed in the axial direction A. Specifically, each of the plurality of magnets 42 has an other-side circumferential extension surface 42a located on the rotor yoke 411 side, a one-side circumferential extension surface 42b located on the side opposite to the rotor yoke 411 side, and radial extension surfaces 42c located on both sides in the circumferential direction. The other-side circumferential extension surface 42a, the one-side circumferential extension surface 42b, and the radial extension surfaces 42c are each linear when viewed in the axial direction A. The one-side circumferential extension surface 42b corresponds to the circumferential extension surface of the present invention.

[0046] When a plurality of magnets 42 that are rectangular when viewed in the axial direction A are arranged in the circumferential direction C on the first surface 411a of the rotor yoke 411, as shown in FIG. 4, a gap occurs between a pair of some of the magnets 42 adjacent to each other in the circumferential direction C.

[0047] The protruding portion 412 is located between the pair of magnets 42 of the part, filling the gap. That is, the pair of magnets 42 adjacent to each other in the circumferential direction C are either in contact with each other or in contact with the protruding portion 412 located therebetween.

[0048] Specifically, in the present embodiment, a pair of auxiliary magnets 422 magnetized in the same direction are located between the main magnets 421 adjacent to each other in the circumferential direction. The protruding portion 412 is located between the pair of auxiliary magnets 422 and in contact with the pair of auxiliary magnets 422. The side of each auxiliary magnet 422 opposite to the protruding portion 412 side is in contact with the main magnet 421.

[0049] That is, on one side and the other side of the circumferential direction C with respect to the protruding portion 412, the N pole of the auxiliary magnet 422 and the S pole of the auxiliary magnet 422 are in contact respectively.

[0050] Although not particularly shown, three or more auxiliary magnets magnetized in the same direction may be located between the main magnets adjacent to each other in the circumferential direction. In this case, two or more protruding portions may be located between the main magnets adjacent to each other in the circumferential direction.

[0051] The protruding portion 412 made of a magnetic material can form a magnetic path through which magnetic flux flows. Therefore, the protruding portion 412 located between the pair of auxiliary magnets 422 magnetized in the same direction can allow the magnetic flux output from one of the pair of auxiliary magnets 422 to flow to the other auxiliary magnet 422.

[0052] That is, in the present embodiment, the plurality of main magnets 421 are located at a predetermined interval in the circumferential direction C. The plurality of auxiliary magnets 422 are located at least two between the main magnets 421 adjacent to each other in the circumferential direction C. The at least two auxiliary magnets 422 located between the main magnets 421 adjacent to each other in the circumferential direction C are magnetized in the same radial direction. The protruding portion 412 is located between the pair of auxiliary magnets 422 adjacent to each other in the circumferential direction C and in contact with the pair of auxiliary magnets 422 in the circumferential direction C.

[0053] The protrusion 412, located between a pair of auxiliary magnets 422 magnetized in the same direction, fills the gap between the pair of auxiliary magnets 422 and forms a magnetic path that allows the magnetic flux output from one of the auxiliary magnets 422 to flow to the other auxiliary magnet 422. As a result, magnetic flux can be efficiently transferred from the auxiliary magnets 422 to the main magnet 421 compared to a configuration where there is space between the pair of auxiliary magnets. Therefore, a rotor 4 with improved magnetic flux in the radial direction R can be obtained.

[0054] Figure 9 is a partially enlarged view of Figure 4. As shown in Figure 9, in this embodiment, the projection 412 has a projection tip surface 412a extending in the circumferential direction C at its tip in the projection direction. That is, the projection 412 has a length in the circumferential direction C even at its tip in the projection direction. This allows the magnets 42 located on one side of the circumferential direction C and the other side of the circumferential direction C relative to the projection 412 to be stably supported in the circumferential direction C by the projection 412. Therefore, even when a large inertial force in the circumferential direction C is generated on the magnets 42 due to the rotation of the rotor 4, a configuration can be obtained that can stably support the magnets 42 in the circumferential direction C. Note that in each figure, the projection tip surface 412a of the projection 412 is straight when viewed in the axial direction A. However, the projection tip surface of the projection may be curved when viewed in the axial direction.

[0055] In this embodiment, the protruding tip surface 412a of the protruding portion 412 does not protrude radially R relative to the pair of magnets 42 located in one circumferential direction C and the other circumferential direction C relative to the protruding portion 412, nor is it recessed radially R relative to the pair of magnets 42.

[0056] In other words, the protruding tip surface 412a of the protruding portion 412 is a surface that extends in the circumferential direction C between the corner between the radially extended surface 42c and the one-sided circumferentially extended surface 42b of the magnet 42 located on one side in the circumferential direction C relative to the protruding portion 412, and the corner between the radially extended surface 42c and the one-sided circumferentially extended surface 42b of the magnet 42 located on the other side in the circumferential direction C relative to the protruding portion 412.

[0057] Thus, since the protrusion 412 does not protrude radially R relative to the pair of magnets 42, the protrusion 412 does not interfere with the stator 3 which is positioned opposite the magnets 42. Furthermore, since the protrusion 412 is not recessed radially R relative to the pair of magnets 42, no space is formed between the circumferential directions of the pair of magnets 42. Therefore, a rotor 4 can be provided that improves the amount of magnetic flux in the radial direction R while preventing interference with the stator 3.

[0058] (Modified Version of Embodiment 1) Figure 10 shows a rotor 4 according to a modified version of Embodiment 1. Figure 10 is an enlarged view of the rotor 4 as seen in the axial direction A. In this modified version, one auxiliary magnet 422 is located between two adjacent main magnets 421 in the circumferential direction. The protrusions 412 are located on one side of the circumferential direction C and the other side of the circumferential direction C of the auxiliary magnet 422. That is, the main magnet 421 is in contact with the protrusion 412 on one side of the circumferential direction C, and the auxiliary magnet 422 is in contact with the other side of the circumferential direction C. Even with this configuration, the protrusions 412 can form a magnetic path that allows the magnetic flux of the auxiliary magnet 422, which is magnetized in the circumferential direction C, to flow. Therefore, compared to a configuration in which there is space between the pair of magnets, the magnetic flux can be efficiently passed from the auxiliary magnet 422 to the main magnet 421. Thus, a rotor 4 with an improved amount of magnetic flux in the radial direction R can be obtained.

[0059] The exemplary rotor 4 described above is a rotor having a rotor core 41 having a cylindrical rotor yoke 411 extending in the axial direction A, and a plurality of magnets 42 positioned in a predetermined order in the circumferential direction C by a Halbach arrangement on a first surface 411a, which is the inner circumferential surface of the rotor yoke 411. The plurality of magnets 42 are each rectangular in shape when viewed in the axial direction A, and include a plurality of main magnets 421 magnetized in the radial direction R and a plurality of auxiliary magnets 422 magnetized in the circumferential direction C. The rotor core 41 has a protruding portion 412 that protrudes in the radial direction R. The protruding portion 412 is located between a pair of magnets 42 adjacent to each other in the circumferential direction C, where at least one of the pair of magnets 42 is an auxiliary magnet 422, and is in contact with the pair of magnets 42 in the circumferential direction C.

[0060] By arranging the multiple magnets 42 of the rotor 4 in a Halbach arrangement, a stronger magnetic field can be created in either the radial direction R inward or radial direction R outward of the rotor 4 than in the other direction. On the other hand, when rectangular magnets 42 are arranged in the circumferential direction C of the rotor yoke 411 when viewed in the axial direction A, a gap is created between adjacent pairs of magnets 42 in the circumferential direction C. If the gap is empty space, magnetic flux leakage occurs between adjacent pairs of magnets 42 in the circumferential direction C, and the amount of magnetic flux toward the radial direction R decreases.

[0061] In the above configuration, the rotor core 41 has a protrusion 412 located between a pair of adjacent magnets 42 in the circumferential direction C. The protrusion 412 can fill the gap that occurs when rectangular magnets 42 are arranged in the circumferential direction C. In this configuration, an auxiliary magnet 422, magnetized in the circumferential direction C, is located on at least one side of the protrusion 412 in either the circumferential direction C or the other circumferential direction C. Therefore, the protrusion 412 can form a magnetic path through which the magnetic flux of the auxiliary magnet 422 flows. That is, the protrusion 412 fills the gap between adjacent magnets 42 in the circumferential direction C while forming a magnetic path in the circumferential direction C. Therefore, with this configuration, a rotor 4 can be obtained that reduces magnetic flux leakage due to gaps and improves the amount of magnetic flux in the radial direction R. Thus, a rotor 4 capable of achieving high torque can be provided.

[0062] Furthermore, the exemplary motor 100 includes a rotor 4 having the above-described configuration and a stator 3 facing the rotor 4 in the radial direction R.

[0063] The rotor 4 of the motor 100 can create a strong magnetic field in the direction in which the stator 3 is located. Therefore, a motor 100 with high torque can be obtained.

[0064] (Embodiment 2) Next, the rotor 104 according to Embodiment 2 will be described with reference to Figures 11 to 13. In this embodiment, the rotor core 141 of the rotor 104 differs from the rotor 4 of Embodiment 1 in that it has a recess 1413 on the second surface 1411b, and the retaining member 143 has a projection 1431a on the surface facing the rotor core 141. In the following, the same configuration as Embodiment 1 will be omitted from the description, and only the configuration that differs from Embodiment 1 will be described.

[0065] In this embodiment, the rotor 104 includes a rotor core 141, a magnet 42, and a holding member 143. Figure 11 is a perspective view showing an example of the configuration of the rotor 104 and the magnet 42. Figure 12 is an enlarged perspective view of the holding member 143 viewed from the radial direction R inward. Figure 13 is an enlarged view of the rotor 104 viewed in the axial direction A.

[0066] In this embodiment, the rotor core 141 has a cylindrical rotor yoke 1411, a protrusion 412, and a recess 1413. The rotor yoke 1411 has a first surface 1411a, which is the surface facing the stator 3 in the radial direction R, and a second surface 1411b on the opposite side. On the first surface 1411a of the rotor yoke 1411, a plurality of magnets 42 are positioned in a predetermined order in the circumferential direction C by a Halbach arrangement.

[0067] As shown in Figure 11, the recess 1413 is located on the second surface 1411b of the rotor yoke 1411. As shown in Figures 11 and 13, the recess 1413 is located in a position aligned radially R with the main magnet 421. In this embodiment, the recess 1413 extends from one axial end A1 to the other axial end A2 of the rotor yoke 1411.

[0068] Although not specifically shown in the figures, in this embodiment as well, one axial side A1 of the rotor yoke 1411 protrudes in the axial direction A more than one axial side A1 of the multiple magnets 42, and the other axial side A2 of the rotor yoke 1411 protrudes in the axial direction A more than the other axial side A2 of the multiple magnets 42. This makes it possible to achieve high torque.

[0069] As shown in Figure 12, the holding member 143 has a cylindrical portion 1431, a one-sided holding portion 432, and a other-sided holding portion 433.

[0070] In this embodiment, the cylindrical portion 1431 has a projection 1431a on the surface facing the rotor yoke 1411. As shown in Figure 13, the projection 1431a is inserted into the recess 1413 of the rotor core 141.

[0071] In other words, in this embodiment, the rotor 104 has a retaining member 143 that holds the rotor core 141 and is located on the second surface 1411b side of the rotor yoke 1411. The plurality of magnets 42 are each rectangular in shape when viewed in the axial direction A, and include a plurality of main magnets 421 magnetized in the radial direction R and a plurality of auxiliary magnets 422 magnetized in the circumferential direction C. The retaining member 143 has a cylindrical portion 1431 that extends in the axial direction A and contacts the second surface 1411b of the rotor yoke 1411. The rotor yoke 1411 has a recess 1413 on the second surface 1411b at a position aligned radially R with the main magnets 421. The cylindrical portion 1431 has a projection 1431a on the surface facing the rotor yoke 1411 that is inserted into the recess 1413.

[0072] This configuration allows the recess 1413 on the second surface 1411b of the rotor yoke 1411 and the protrusion 1431a of the retaining member 143 inserted into the recess 1413 to act as a rotation stopper, preventing the rotor yoke 1411 from shifting in the circumferential direction C relative to the retaining member 143. On the other hand, in a configuration in which the rotor yoke has a recess, the recess may obstruct the magnetic flux flowing circumferentially through the rotor yoke.

[0073] In contrast, in the above-described configuration, the recess 1413 is located in the rotor yoke 1411 at a position where the main magnet 421, which has magnetic flux flowing in the radial direction R, is fixed, rather than at a position where the auxiliary magnet 422, which has magnetic flux flowing in the circumferential direction C, is fixed. That is, the recess 1413 is located in a part where it is not necessary for magnetic flux to flow in the circumferential direction C. This makes it possible to position the recess 1413 in the rotor yoke 1411 while suppressing obstruction of the flow of magnetic flux. Thus, in a configuration in which the rotor yoke 1411 can be fixed to the holding member 143 in the circumferential direction C, a rotor 104 capable of achieving high torque can be provided.

[0074] In this embodiment as well, the one-sided holding portion 432 has a groove portion 432a that extends in the circumferential direction into which the axial end A of the rotor yoke 1411 is inserted in the axial direction A.

[0075] This makes it possible to provide a rotor 104 that can achieve high torque in a configuration in which the rotor yoke 1411 can be fixed to the holding member 143 in the axial, radial, and circumferential directions.

[0076] (Other Embodiments) Although embodiments of the present invention have been described above, the embodiments described above are merely examples for carrying out the present invention. Therefore, the invention is not limited to the embodiments described above, and it is possible to carry out the invention by appropriately modifying the embodiments described above without departing from the spirit of the invention.

[0077] In the embodiments described above, an in-wheel motor positioned within the drive wheel of an electric motorcycle was described as an example of application of the motor 100, but the motor of this embodiment may also be applied to other configurations.

[0078] In the embodiments described above, the motor 100 was described as a so-called outer rotor type motor in which the rotors 4 and 104 are located radially outward R of the stator 3. However, the motor may also be a so-called inner rotor type motor in which the rotor is located radially inward of the stator. In this case, the first surface of the rotor yoke is the outer surface, and the second surface is the inner surface. That is, a plurality of magnets are arranged in a predetermined order in the circumferential direction on the outer surface of the rotor yoke in a Halbach arrangement, and a holding member is located on the inner surface side of the rotor yoke.

[0079] In each of the above embodiments, the axial length A of the rotor yokes 411 and 1411 is the same as the axial length A of the projection 412. However, the axial length of the rotor yoke and the axial length of the projection may be different.

[0080] In each of the above embodiments, the rotor yokes 411 and 1411 protrude in one axial direction A1 and the other axial direction A2 relative to the plurality of magnets 42. However, the rotor yoke does not have to protrude in one axial direction relative to the plurality of magnets. The rotor yoke does not have to protrude in the other axial direction relative to the plurality of magnets.

[0081] In each of the above embodiments, the projection 412 has a projection tip surface 412a extending in the circumferential direction C at its tip in the projection direction. That is, the projection is trapezoidal when viewed in the axial direction. However, the projection does not have to have a surface extending in the circumferential direction at its tip in the projection direction. For example, the projection may be triangular when viewed in the axial direction.

[0082] In each of the above embodiments, the protruding tip surface 412a of the protruding portion 412 does not protrude radially R with respect to the pair of magnets 42 located in one circumferential direction C and the other circumferential direction C relative to the protruding portion 412, nor is it recessed radially R with respect to the pair of magnets 42. However, the protruding tip surface of the protruding portion may protrude radially with respect to the pair of magnets located in one circumferential direction and the other circumferential direction relative to the protruding portion. The protruding tip surface of the protruding portion may also be recessed radially with respect to the pair of magnets.

[0083] In each of the above embodiments, the one-sided retaining portion 432 of the retaining members 43, 143 has a groove 432a into which the axial end A of the rotor core 41, 141 is inserted in the axial direction A. However, the other-sided retaining portion of the retaining member may also have a groove.

[0084] In the above embodiment 1, the multiple magnets 42 protrude from the multiple teeth 312 in one axial direction A1 and the other axial direction A2. However, the multiple magnets do not have to protrude from the multiple teeth in one axial direction. The multiple magnets do not have to protrude from the multiple teeth in the other axial direction.

[0085] In the above embodiment 2, the rotor core 141 has a protrusion 412. However, the rotor core does not have to have a protrusion.

[0086] In the above embodiment 2, the recess 1413 of the rotor core 141 extends from one axial end A1 to the other axial end A2 of the rotor yoke 1411. However, the recess may extend intermittently in the axial direction. The recess may extend in different axial ranges at different circumferential positions.

[0087] (Example Configuration) This technology can also be configured as follows:

[0088] (1) The rotor comprises a rotor core having a cylindrical rotor yoke extending in the axial direction, and a plurality of magnets positioned in a predetermined order in the circumferential direction by a Halbach arrangement on a first surface which is either the inner or outer circumferential surface of the rotor yoke. The plurality of magnets are each rectangular in shape when viewed in the axial direction and include a plurality of main magnets magnetized in the radial direction and a plurality of auxiliary magnets magnetized in the circumferential direction. The rotor core has a projection that protrudes in the radial direction. The projection is located between a pair of magnets where at least one of the circumferentially adjacent magnets is an auxiliary magnet, and is in contact with the pair of magnets in the circumferential direction.

[0089] (2) In the rotor described in (1), the plurality of main magnets are positioned at predetermined intervals in the circumferential direction. At least two of the plurality of auxiliary magnets are positioned between adjacent main magnets in the circumferential direction. The at least two auxiliary magnets positioned between adjacent main magnets in the circumferential direction are magnetized in the same radial direction. The protrusion is positioned between a pair of adjacent auxiliary magnets in the circumferential direction and is in contact with the pair of auxiliary magnets in the circumferential direction.

[0090] (3) In the rotor described in (1) or (2), the projection has a projection tip surface extending in the circumferential direction at the tip in the projection direction.

[0091] (4) In the rotor described in (3), each of the plurality of magnets has a circumferentially extended surface located on the side opposite to the rotor yoke side of the radial surface, and radially extended surfaces located on both sides in the circumferential direction. The protruding tip surface of the protrusion is a surface that extends in the circumferential direction between the corner between the radially extended surface and the circumferentially extended surface of the magnet located on one side of the circumferential direction relative to the protrusion, and the corner between the radially extended surface and the circumferentially extended surface of the magnet located on the other side of the circumferential direction relative to the protrusion.

[0092] (5) In the rotor described in any one of (1) to (4), one axial side of the rotor yoke protrudes in the axial direction more than one axial side of the plurality of magnets, and the other axial side of the rotor yoke protrudes in the axial direction more than the other axial side of the plurality of magnets.

[0093] (6) The rotor comprises a rotor core having a cylindrical rotor yoke extending in the axial direction, and a plurality of magnets positioned in a predetermined order in the circumferential direction by a Halbach arrangement on a first surface which is either the inner or outer surface of the rotor yoke. A retaining member is located on the second surface side which is the other surface of the inner or outer surface of the rotor yoke and holds the rotor core. The plurality of magnets are each rectangular in shape when viewed in the axial direction and include a plurality of main magnets magnetized in the radial direction and a plurality of auxiliary magnets magnetized in the circumferential direction. The retaining member has a cylindrical portion that extends in the axial direction and contacts the second surface of the rotor yoke. The rotor yoke has recesses on the second surface at positions that are radially aligned with the main magnets. The cylindrical portion has protrusions on the rotor yoke side that are inserted into the recesses.

[0094] (7) In the rotor described in (6), the retaining member has an annular one-side retaining portion in the axial direction that extends radially from one axial side of the cylindrical portion and contacts one axial end face of the rotor yoke, and an annular other-side retaining portion in the axial direction that extends radially from the other axial side of the cylindrical portion and contacts the other axial end face of the rotor yoke. Either the one-side retaining portion or the other-side retaining portion has a circumferentially extending groove into which the axial end of the rotor yoke is inserted in the axial direction.

[0095] (8) In the rotor described in (6) or (7), one axial side of the rotor yoke protrudes axially more than one axial side of the plurality of magnets, and the other axial side of the rotor yoke protrudes axially more than the other axial side of the plurality of magnets.

[0096] (9) The motor comprises a rotor as described in any one of (1) to (8), and a stator facing radially opposite the plurality of magnets of the rotor.

[0097] In the motor described in (10) and (9), the stator has a cylindrical core back portion extending in the axial direction, and a plurality of teeth extending radially from the core back portion, the tips of which face the plurality of magnets. One axial side of the plurality of magnets protrudes in the axial direction more than one axial side of the plurality of teeth, and the other axial side of the plurality of magnets protrudes in the axial direction more than the other axial side of the plurality of teeth.

[0098] The configuration of the present invention is applicable to a rotor in which magnets are arranged in a Halbach array.

[0099] 2 Fixed shaft 3 Stator 4, 104 Rotor 5 Bearing 31 Stator core 32 Coil 33 Insulator 41, 141 Rotor core 42 Magnet 42a Other side circumferentially extended surface 42b One side circumferentially extended surface (circumferentially extended surface located on the opposite side from the rotor yoke among the radial surfaces) 42c Radially extended surface 43, 143 Holding member 100 Motor 311 Core back part 312 Teeth 411, 1411 Rotor yoke 411a, 1411a First surface 411b, 1411b Second surface 412 Projection part 412a Projection tip surface 421 Main magnet 422 Auxiliary magnet 431, 1431 Cylinder part 432 One side holding part 432a Groove part 433 Other side holding part 1413 Recess 1431a Projection P Central axis

Claims

1. A rotor having a rotor core having a cylindrical rotor yoke extending in the axial direction, and a plurality of magnets positioned in a predetermined order in the circumferential direction by a Halbach arrangement on a first surface which is either the inner or outer circumferential surface of the rotor yoke, wherein each of the plurality of magnets is rectangular in shape when viewed in the axial direction and includes a plurality of main magnets magnetized in the radial direction and a plurality of auxiliary magnets magnetized in the circumferential direction, the rotor core having a projection that protrudes in the radial direction, the projection being positioned between a pair of magnets where at least one of the circumferentially adjacent magnets is the auxiliary magnet, and in circumferential contact with the pair of magnets.

2. The rotor according to claim 1, wherein the plurality of main magnets are positioned at predetermined intervals in the circumferential direction, at least two of the plurality of auxiliary magnets are positioned between adjacent main magnets in the circumferential direction, the at least two auxiliary magnets positioned between adjacent main magnets in the circumferential direction are magnetized in the same radial direction, and the protrusion is positioned between a pair of adjacent auxiliary magnets in the circumferential direction and is in circumferential contact with the pair of auxiliary magnets.

3. The rotor according to claim 1, wherein the protrusion has a protruding tip surface extending in the circumferential direction at the tip in the direction of protrusion.

4. The rotor according to claim 3, wherein each of the plurality of magnets has a circumferentially extended surface located on the side opposite to the rotor yoke side of the radial surface, and radially extended surfaces located on both sides in the circumferential direction, and the protruding tip surface of the protrusion is a surface that extends in the circumferential direction between the corner between the radially extended surface and the circumferentially extended surface of the magnet located on one side of the circumferential direction relative to the protrusion, and the corner between the radially extended surface and the circumferentially extended surface of the magnet located on the other side of the circumferential direction relative to the protrusion.

5. A rotor according to claim 1, wherein one axial side of the rotor yoke protrudes in the axial direction more than one axial side of the plurality of magnets, and the other axial side of the rotor yoke protrudes in the axial direction more than the other axial side of the plurality of magnets.

6. A rotor having a rotor core having a cylindrical rotor yoke extending in the axial direction, and a plurality of magnets positioned in a predetermined order in the circumferential direction by a Halbach arrangement on a first surface which is either the inner or outer circumferential surface of the rotor yoke, wherein a retaining member is located on the second surface side which is the other surface of the inner or outer circumferential surface of the rotor yoke and holds the rotor core, wherein the plurality of magnets are each rectangular in shape when viewed in the axial direction and include a plurality of main magnets magnetized in the radial direction and a plurality of auxiliary magnets magnetized in the circumferential direction, the retaining member has a cylindrical portion extending in the axial direction and in contact with the second surface of the rotor yoke, the rotor yoke has a recess on the second surface at a position radially aligned with the main magnets, and the cylindrical portion has a projection on the rotor yoke side that is inserted into the recess.

7. The rotor according to claim 6, wherein the retaining member has: an annular one-side retaining portion in the axial direction extending radially from one axial side of the cylindrical portion and in contact with one axial end face of the rotor yoke; and an annular other-side retaining portion in the axial direction extending radially from the other axial side of the cylindrical portion and in contact with the other axial end face of the rotor yoke, wherein either the one-side retaining portion or the other-side retaining portion has a circumferentially extending groove into which the axial end of the rotor yoke is inserted in the axial direction.

8. A rotor according to claim 6, wherein one axial side of the rotor yoke protrudes in the axial direction more than one axial side of the plurality of magnets, and the other axial side of the rotor yoke protrudes in the axial direction more than the other axial side of the plurality of magnets.

9. A motor comprising a rotor according to any one of claims 1 to 8, and a stator radially opposite to the plurality of magnets of the rotor.

10. A motor according to claim 9, wherein the stator has a cylindrical core back portion extending in the axial direction, and a plurality of teeth extending radially from the core back portion, the tips of which face the plurality of magnets, and one axial side of the plurality of magnets protrudes in the axial direction more than one axial side of the plurality of teeth, and the other axial side of the plurality of magnets protrudes in the axial direction more than the other axial side of the plurality of teeth.

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