Rotor and electric motor

Abstract

To reduce cogging torque of a rotor and a motor. A rotor core (20) has a plurality of magnet arrangement holes (21). A plurality of permanent magnets (30) are arranged inside each of the plurality of magnet arrangement holes (21). A rotating shaft (10) is fixed to the rotor core (20) and rotates around an axial direction thereof. Each of the magnet arrangement holes (21) has a first protruding portion (22) at a portion of a first inner surface (21a) opposite to a second inner surface (21b) in a rotational direction. Each of the permanent magnets (30) has a second protruding portion (30a) facing the first inner surface (21a) where the first protruding portion (22) is located. The first protruding portion (22) and the second protruding portion (30a) are located near an opening of the magnet arrangement hole (21) in the axial direction of the rotating shaft (10) and are arranged on opposite sides of the magnet arrangement hole (21) in the axial direction of the rotating shaft (10).

Description

Technical Field

[0001] This disclosure relates to electric motors used in various types of equipment, including household electrical appliances and industrial equipment, and particularly to the rotors of electric motors. Background Technology

[0002] Electric motors are used in various electrical devices, such as household appliances and industrial equipment. One known type of electric motor is the IPM (Interior Permanent Magnet) motor. An IPM motor rotor typically includes: a rotor core; permanent magnets disposed in various magnet mounting holes within a plurality of magnet mounting holes provided in the rotor core; and a rotating shaft fixed to the center of the rotor core, penetrating through it. In an IPM motor, a torque is generated to rotate the rotor by allowing the magnetic flux produced by the permanent magnets of the rotor to pass through the stator.

[0003] Previously, as such motors, there were known IPM motors with rotors having multiple magnet mounting holes arranged radially on a rotor core (Patent Document 1).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-46386 Summary of the Invention

[0007] In conventional rotors, a predetermined space is sometimes provided between the rotor core and the permanent magnet to improve the insertion accuracy of the permanent magnet into the magnet mounting hole. In this case, if the permanent magnet is inserted into the magnet mounting hole, its position within the hole may deviate. As a result, the difference in magnetic flux density between the poles of the permanent magnet increases, leading to a problem of increased cogging torque.

[0008] This disclosure is intended to solve the problems mentioned above, and its purpose is to provide a rotor and motor capable of reducing cogging torque.

[0009] The rotor disclosed herein comprises: a rotor core having a plurality of magnet mounting holes; a plurality of permanent magnets respectively disposed inside the plurality of magnet mounting holes; and a rotating shaft fixed to the rotor core, the rotating shaft having an axis and rotating about the axis along a predetermined rotation direction. The magnet mounting holes each have a first inner surface and a second inner surface opposite to each other in the rotation direction, and a first protrusion is partially present on the first inner surface. The permanent magnets each have a second protrusion facing the first inner surface where the first protrusion is located, the first protrusion and the second protrusion being located near opposing openings of the magnet mounting holes along the axis.

[0010] The electric motor disclosed herein includes: the rotor; and a stator configured opposite to the rotor and generating a magnetic force acting on the rotor.

[0011] According to this disclosure, it is possible to provide a rotor and an electric motor capable of reducing cogging torque. Attached Figure Description

[0012] Figure 1 This is a perspective view of an electric motor according to one embodiment of the present disclosure.

[0013] Figure 2 This is a perspective view of the rotor of an electric motor according to one embodiment of the present disclosure.

[0014] Figure 3 This is a top view of the main part of the rotor of an electric motor according to one embodiment of the present disclosure.

[0015] Figure 4 This is a cross-sectional view of the main part of the rotor of an electric motor according to one embodiment of the present disclosure.

[0016] Figure 5 This is a top view of the main part of the rotor of an electric motor according to one embodiment of the present disclosure.

[0017] Figure 6 This is a top view of the main part of the rotor of an electric motor according to one embodiment of the present disclosure. Detailed Implementation

[0018] The embodiments of this disclosure will now be described. Furthermore, the embodiments described below represent specific examples of this disclosure. Therefore, the numerical values, constituent elements, arrangement and connection patterns of constituent elements, and processes and their order shown in the following embodiments are merely examples and are not intended to limit this disclosure. Therefore, constituent elements in the following embodiments that are not described in the independent claims representing the highest-level concept of this disclosure will be described as arbitrary constituent elements.

[0019] Furthermore, the figures are schematic diagrams and not necessarily strict representations. Also, in each figure, structures substantially identical to those in other figures are labeled with the same reference numerals, and repetitive descriptions are omitted or simplified.

[0020] (Implementation Method)

[0021] First, regarding the general structure of the motor 1 in the embodiment, using... Figure 1 Please provide an explanation. Figure 1 This is a perspective view of the electric motor 1 according to the embodiment.

[0022] like Figure 1As shown, the electric motor 1 includes a rotor 2 and a stator 3. The electric motor 1 in this embodiment is an inner rotor type motor in which the rotor 2 is disposed inside the stator 3. That is, the stator 3 is configured to surround the rotor 2.

[0023] The rotor 2 rotates under the magnetic force generated by the stator 3. Specifically, the rotor 2 has a rotation shaft 10 and rotates around the axis C of the rotation shaft 10.

[0024] The rotor 2 generates a magnetic force acting on the stator 3. The rotor 2 is structured such that multiple N and S poles, which constitute the main magnetic flux, are repeatedly present along the entire direction of rotation around the axis C (hereinafter sometimes referred to as the circumferential direction, the circular direction, or the direction of rotation). In this embodiment, the direction of the main magnetic flux generated by the rotor 2 is orthogonal to the direction along the axis C of the rotation axis 10 (hereinafter sometimes referred to as the axial direction or the direction of axis C). That is, the direction of the main magnetic flux generated by the rotor 2 is radial (hereinafter referred to as radial). Furthermore, at any point near the motor 1, including the motor 1, the circumferential, axial, and radial directions are all orthogonal to each other. Figure 1 The arrow shown indicates the direction of the axis C of the rotation axis 10.

[0025] The rotor 2 is configured to be separated from the stator 3 by an air gap. Specifically, there is a small air gap between the surface of the rotor 2 and the surface of the stator 3. The rotor 2 is a permanent magnet embedded type rotor (IPM rotor) with permanent magnets embedded in the iron core, as described later. Therefore, the motor 1 of this embodiment is an IPM motor.

[0026] The stator 3 is configured to face the rotor 2 across an air gap, generating a magnetic force acting on the rotor 2. Specifically, the stator 3 is configured to surround the rotor core 20 of the rotor 2. The stator 3 and the rotor 2 together form a magnetic circuit.

[0027] The stator 3 is configured to alternately generate N and S poles as the main magnetic flux along the circumferential direction on the air gap surface. In this embodiment, the stator 3 has a stator core 3a (stator core) and a winding coil 3b (stator coil).

[0028] The stator core 3a is provided with a plurality of teeth 3a1 protruding toward the rotor core 20 of the rotor 2. Specifically, the plurality of teeth 3a1 are arranged to protrude toward the axis C of the rotation shaft 10. In addition, the plurality of teeth 3a1 are arranged at equal intervals in the circumferential direction. Therefore, the plurality of teeth 3a1 extend radially in a direction orthogonal to the axis C of the rotation shaft 10.

[0029] The stator core 3a is, for example, composed of multiple steel plates stacked in the direction of the axis C of the rotation shaft 10. The multiple steel plates are, for example, electromagnetic steel plates that have been punched into a specified shape. In addition, the stator core 3a is not limited to a stack of multiple steel plates, but can also be a block made of magnetic material.

[0030] The winding coil 3b is wound around each of the multiple teeth 3a1 of the stator core 3a. Specifically, the winding coil 3b is wound around each tooth 3a1 through an insulator. Each winding coil 3b is composed of a unit coil of each of the three phases: U-phase, V-phase, and W-phase, with an electrical phase difference of 120 degrees. That is, the winding coil 3b wound around each tooth 3a1 is driven by three-phase AC current energized separately in the phase units of U-phase, V-phase, and W-phase. As a result, the main magnetic flux of the stator 3 is generated in each tooth 3a1.

[0031] In addition, the winding coil 3b is composed of a winding with a circular or rectangular cross-section, which is made of a metal material such as copper with an insulating coating applied to its surface.

[0032] In the electric motor 1 configured in this way, when the winding coil 3b of the stator 3 is energized, the excitation current flows through the winding coil 3b and generates a magnetic field. This generates a magnetic flux from the stator 3 toward the rotor 2. Conversely, a magnetic flux is generated in the rotor 2 toward the stator 3. That is, the permanent magnets of the rotor 2 generate a magnetic flux passing through the stator 3. The magnetic force generated by the interaction between the magnetic flux generated by the stator 3 and the magnetic flux generated by the rotor 2 becomes the torque that causes the rotor 2 to rotate around the rotation axis 10.

[0033] Next, regarding the detailed structure of the rotor 2 in this embodiment, refer to... Figure 1 and use Figure 2 and Figure 3 Please provide an explanation. Figure 2 This is a perspective view of rotor 2 in the embodiment. Figure 3 This is a top view of the main part of rotor 2 in the embodiment. Figure 2 , Figure 3 In the original text, the rotation axis 10 is omitted.

[0034] For example Figures 1-3 As shown, the rotor 2 has a rotating shaft 10, a rotor core 20, and multiple permanent magnets 30.

[0035] The rotating shaft 10 is an elongated shaft that serves as the center when the rotor 2 rotates. The rotating shaft 10 is, for example, a metal rod, fixed to the center of the rotor 2. Specifically, the rotating shaft 10 is fixed to the rotor core 20. In this embodiment, the rotating shaft 10 is fixed to the rotor core 20 in a manner that protrudes from both sides of the rotor 2 and penetrates the center of the rotor core 20. The rotating shaft 10 is fixed to the rotor core 20 by press-fitting or hot-pressing into a through hole 201 formed in the center of the rotor core 20.

[0036] Additionally, although not shown, a first portion of the rotating shaft 10 protruding from one side of the rotor 2 is supported by a first bearing, and a second portion of the rotating shaft 10 protruding from the other side of the rotor 2 is supported by a second bearing. A load driven by the electric motor 1 is mounted at either the first or second portion of the rotating shaft 10.

[0037] The rotor core 20 (rotor core) is, for example, composed of multiple steel plates stacked in the direction along the axis C of the rotation shaft 10. These multiple steel plates are, for example, electromagnetic steel plates that have been punched into a predetermined shape and are fixed together by means of mortise and tenon joints. Furthermore, the rotor core 20 is not limited to a stack of multiple steel plates; it can also be a block made of magnetic material.

[0038] The rotor core 20 is a core having multiple magnet mounting holes 21. These holes 21 are for mounting permanent magnets 30. Specifically, permanent magnets 30 are inserted into the magnet mounting holes 21. That is, the magnet mounting holes 21 are magnet insertion holes for inserting permanent magnets 30. One permanent magnet 30 is inserted into each magnet mounting hole 21. As an example, the rotor 2 is a 10-pole rotor with 10 poles. Therefore, the rotor core 20 has 10 magnet mounting holes 21 and 10 permanent magnets 30. However, it is not particularly limited to this, and other pole numbers can also be used.

[0039] Furthermore, in this embodiment, the magnet mounting hole 21 is a through hole that penetrates the rotor core 20 along the axis C of the rotation shaft 10. Therefore, in any cross-section obtained by cutting with a plane orthogonal to the rotation shaft 10, the cross-sectional shape of the magnet mounting hole 21 is the same in the direction of the axis C of the rotation shaft 10. That is, magnet mounting holes 21 of the same shape are formed on all the steel plates constituting the rotor core 20. In addition, the magnet mounting hole 21 only needs to be able to mount the permanent magnet 30, and does not have to be a through hole.

[0040] like Figure 1 , Figure 2As shown, multiple magnet mounting holes 21 are arranged radially around the rotation axis 10. Furthermore, the multiple magnet mounting holes 21 are arranged at equal intervals along the circumference of the rotor core 20 (the rotation direction of the rotation axis 10). Each of the multiple magnet mounting holes 21 extends radially (in a direction orthogonal to the axis C of the rotation axis 10) of the rotor core 20 when viewed from above. That is, the magnet mounting holes 21 are elongated in the radial direction of the rotor core 20, and their radial length is longer than their length in the rotation direction (circumferential direction). Alternatively, the magnet mounting holes 21 can also be designed to be elongated in the rotation direction (circumferential direction) of the rotor core 20, and their length in the rotation direction (circumferential direction) is longer than their radial length.

[0041] Multiple elongated magnet mounting holes 21 are formed in a spoke-like pattern around the rotation shaft 10. That is, the rotor 2 is a spoke-type IPM rotor, and the motor 1 is a spoke-type IPM motor. In this embodiment, the top view shape of each magnet mounting hole 21 is approximately rectangular with the radial direction of the rotor core 20 as its length. Furthermore, the top view shape of each magnet mounting hole 21 is the same as the top view shape of the other magnet mounting holes 21.

[0042] like Figure 2 As shown, permanent magnets 30 are inserted into the magnet mounting holes 21 of the rotor 2 along the direction of the axis C of the rotation shaft 10, and permanent magnets 30 are respectively mounted in the multiple magnet mounting holes 21. In this embodiment, the permanent magnets 30 are inserted from above the axis C of the rotation shaft 10 (above the paper), but they can also be inserted from below the axis C (below the paper).

[0043] Here, the surface of the rotor core 20 into which the permanent magnet 30 is inserted (in) Figure 2 The surface above the paper is designated as the insertion surface 20a, and the surface opposite to the insertion surface 20a in the axial direction of the rotation axis 10 is designated as the bottom surface 20b.

[0044] In this embodiment, the permanent magnet 30 is, for example, a sintered magnet. The multiple permanent magnets 30 are configured such that the direction of their magnetic poles is circumferential to the rotor core 20 (the direction of rotation of the rotating shaft 10). That is, the permanent magnets 30 are magnetized such that the direction of their magnetic poles is circumferential to the rotor core 20. Furthermore, the S and N poles of two adjacent permanent magnets 30 have opposite directions.

[0045] The top view shape and size of the permanent magnet 30 are approximately the same as those of the magnet mounting hole 21, and the permanent magnet 30 is fitted into the magnet mounting hole 21. Therefore, the top view shape of the permanent magnet 30 is a long, rectangular strip. As an example, the permanent magnet 30 is a plate-shaped cuboid with a thickness in a direction orthogonal to the radial direction of the rotor core 20. Alternatively, the permanent magnet 30 can also be divided into multiple parts.

[0046] In each magnet mounting hole 21, there is a gap (space, void) of a certain size between the outer surface of the permanent magnet 30 and the inner surface of the magnet mounting hole 21. An adhesive for bonding and fixing the permanent magnet 30 to the magnet mounting hole 21 can be provided in this gap.

[0047] The permanent magnet 30 is, for example, composed of sintered magnets based on the Nd-Fe-B system or sintered ferrite magnets. Alternatively, it can be a bonded magnet formed from magnet powders such as Nd-Fe-B system magnet powder and ferrite system magnet powder, resin materials, and a small amount of additives.

[0048] Furthermore, regarding the magnetization of the permanent magnet 30, it can be performed either after the permanent magnet 30 is placed in the magnet placement hole 21, or it can be pre-magnetized before the permanent magnet 30 is inserted into the magnet placement hole 21. However, considering the operability of inserting the permanent magnet 30 into the magnet placement hole 21, it is better to magnetize it after the permanent magnet 30 is inserted into the magnet placement hole 21.

[0049] In addition, a coating layer 30b is formed by coating the permanent magnet 30 with a coating material made of resin, thereby covering the area around the permanent magnet 30.

[0050] like Figure 3 As shown, in a top view (viewed from the axis C of the rotation axis 10), the magnet mounting hole 21 has a first inner surface 21a and a second inner surface 21b opposite to each other in the rotational direction. For the first inner surface 21a and the second inner surface 21b, for example, in the direction from the axis C of the rotation axis 10, Figure 1 When observing the magnet mounting hole 21 in the direction indicated by the arrow, the first inner surface 21a is positioned to the right of the second inner surface 21b.

[0051] The permanent magnets 30 are fixed within the magnet mounting holes 21 in a manner that they contact the second inner surface 21b. That is, each permanent magnet 30 is positioned within its respective magnet mounting hole 21 at a distance from the axis C of the rotation shaft 10. Figure 1 When observing the magnet configuration hole 21 in the direction indicated by the arrow, for example, near the position (left side) of the second inner surface 21b.

[0052] The following details the permanent magnet 30 and the first inner surface 21a and the second inner surface 21b of the magnet mounting hole 21, referring to... Figure 4 Please provide an explanation.

[0053] Figure 4 This is a cross-sectional view of each magnet mounting hole 21 viewed from a direction orthogonal to the axis C of the rotation axis 10 (axial direction). Figure 3 (Sectional view along line IV-IV).

[0054] When viewed from the axial direction of the rotating shaft 10, the magnet placement hole 21 has an opening on the bottom surface 20b and the insertion surface 20a of the rotor core 20 for inserting and placing the permanent magnet 30.

[0055] like Figure 4 As shown, a first protrusion 22 is provided on a portion of the first inner surface 21a of the magnet mounting hole 21. The first protrusion 22 is provided at the lowermost part of the magnet mounting hole 21 (the side below the paper, i.e., the bottom surface 20b side) in the axial direction of the rotation shaft 10.

[0056] The permanent magnet 30 has a second protrusion 30a facing the first inner surface 21a where the first protrusion 22 is located. The second protrusion 30a is provided at the uppermost part of the magnet placement hole 21 (the upper side of the paper, i.e. the insertion surface 20a side) in the axial direction of the rotation shaft 10.

[0057] Therefore, the first protrusion 22 and the second protrusion 30a are respectively located near the opening of the magnet mounting hole 21, i.e., near the bottom surface 20b and the insertion surface 20a of the rotor core 20, in the direction of the axis C of the rotation shaft 10, and are arranged on opposite sides in the axial direction of the rotation shaft 10. More specifically, the first protrusion 22 is provided on the bottom surface 20b, and the second protrusion 30a is provided with a portion of its portion located on the insertion surface 20a. In the magnet mounting hole 21, the two are arranged on opposite sides in the axial direction of the rotation shaft 10, i.e., on the insertion surface 20a side and the bottom surface 20b side, respectively.

[0058] Alternatively, the first protrusion 22 can be formed at the uppermost part of the magnet placement hole 21 in the axial direction of the rotation shaft 10, and the second protrusion 30a can be formed at the lowermost part of the magnet placement hole 21 in the axial direction of the rotation shaft 10. However, since the permanent magnet 30 is not inserted from the side where the first protrusion 22 exists, the first protrusion 22 is disposed on the bottom surface 20b side. The permanent magnet 30 is inserted into the magnet placement hole 21 from the insertion surface 20a side with the second protrusion 30a not facing the side opposite to the first protrusion 22.

[0059] The first protrusion 22 and the second protrusion 30a do not contact each other. The second protrusion 30a can be formed by deforming the shape of the permanent magnet 30 itself, or it can be formed by the coating layer alone.

[0060] As described above, the first protrusion 22 and the second protrusion 30a are arranged on opposite sides of each other in the axial direction of the rotation shaft 10 in the magnet mounting hole 21. Therefore, when the permanent magnet 30 is inserted into the magnet mounting hole 21, the contact distance between the second protrusion 30a and the first inner surface 21a can be reduced, and stress can be prevented from being applied to the magnet mounting hole 21 (rotor core 20).

[0061] Alternatively, the surface 31 of the first protrusion 22 opposite to the second protrusion 30a may be arc-shaped when viewed radially. Furthermore, in the rotational direction, the combined thickness of the permanent magnet 30 and the second protrusion 30a is approximately the same as or smaller than the dimension between the first inner surface 21a and the second inner surface 21b. This prevents the second protrusion 30a from getting stuck when the permanent magnet 30 is inserted into the magnet placement hole 21, thus preventing difficulty in inserting the permanent magnet 30.

[0062] In the rotational direction, the dimension w1 of the first protrusion 22 (the length of the portion protruding from the first inner surface 21a) is larger than the dimension w2 of the second protrusion 30a (the length of the portion protruding from the permanent magnet 30). Furthermore, in the rotational direction, the dimension between the first protrusion 22 and the second inner surface 21b is smaller than the thickness of the portion of the permanent magnet 30 excluding the second protrusion 30a. This prevents the permanent magnet 30 from falling off the bottom surface 20b side when it is inserted into the magnet placement hole 21.

[0063] Furthermore, preferably, in the rotational direction, the combined thickness of the permanent magnet 30 and the second protrusion 30a is substantially the same as the dimension between the first inner surface 21a and the second inner surface 21b. According to this structure, the permanent magnet 30 contacts the second inner surface 21b, and the second protrusion 30a contacts the first inner surface 21a. Moreover, due to this contact, the permanent magnet 30 can be fixed in place without moving.

[0064] At this point, it could also be, such as Figure 5 As shown, when viewed from the axis C of the rotation axis 10, the two corners 20c of the magnet placement hole 21 connected to the first inner surface 21a are arc-shaped, and the radius of the outer peripheral surface of the corner 30c of the second protrusion 30a is larger than that of the corner 20c. Therefore, inserting the permanent magnet 30 into the magnet placement hole 21 becomes easier.

[0065] Alternatively, it could be, such as Figure 6 As shown, the second protrusion 30a has a notch 30a1 in the radial direction orthogonal to the axis C of the rotation shaft 10. Specifically, the notch 30a1 is located at the center of the second protrusion 30a in the radial direction. The notch 30a1 can be used as a gap for applying adhesive. Multiple notches 30a1 may also be formed.

[0066] By setting the structure as described above, the permanent magnets 30 inserted into each magnet placement hole 21 can contact one side of the surface (in this embodiment, the second inner surface 21b on the left side of the rotation direction) within each magnet placement hole 21, and the permanent magnets 30 can be fixed so that they do not move.

[0067] Therefore, deviations in the placement positions of the permanent magnets 30 in each magnet placement hole 21 can be suppressed. As a result, the following advantages are obtained: the difference in magnetic flux density in each permanent magnet 30 can be reduced, and the increase in torque fluctuation or cogging torque can be prevented.

[0068] Furthermore, the above-described embodiment is merely an example, and this disclosure is not limited thereto; appropriate modifications are permissible. For instance, a portion of the structure of the above embodiment may be replaced with other known structures. Additionally, structures not mentioned in the above embodiments are arbitrary; for example, known structures may be appropriately selected and combined with this disclosure.

[0069] (Implementation Mode)

[0070] The following describes the implementation of this disclosure.

[0071] The rotor of the first embodiment of this disclosure comprises: a rotor core having a plurality of magnet mounting holes; a plurality of permanent magnets disposed inside each of the plurality of magnet mounting holes; and a rotating shaft fixed to the rotor core, the rotating shaft having an axis and rotating about the axis along a predetermined rotation direction. The magnet mounting holes each have a first inner surface and a second inner surface opposite to each other in the rotation direction, and a first protrusion is partially present on the first inner surface. The permanent magnets each have a second protrusion facing the first inner surface where the first protrusion is located. The first and second protrusions are located near opposite openings of the magnet mounting holes along the axis.

[0072] Based on the first embodiment, in the rotor of the second embodiment of this disclosure, the surface of the first protrusion opposite to the second protrusion is arc-shaped.

[0073] Based on the first embodiment, in the rotor of the third embodiment of this disclosure, the size of the first protrusion is larger than the size of the second protrusion in the rotational direction.

[0074] Based on the third embodiment, in the rotor of the fourth embodiment of this disclosure, the dimension between the first protrusion and the second inner surface in the rotational direction is smaller than the thickness dimension of the permanent magnet.

[0075] Based on the third embodiment, in the rotor of the fifth embodiment of this disclosure, in the rotational direction, the combined thickness of the permanent magnet and the second protrusion is approximately the same as or smaller than the dimension between the first inner surface and the second inner surface.

[0076] Based on the third embodiment, in the rotor of the sixth embodiment of this disclosure, the permanent magnet is in contact with the second inner surface, and the second protrusion is in contact with the first inner surface.

[0077] Based on the sixth embodiment, in the rotor of the seventh embodiment of this disclosure, when viewed from the axial direction of the rotating shaft, the corner of the magnet placement hole connected to the first inner surface is arc-shaped, and the radius of the outer peripheral surface of the corner of the second protrusion is larger than the radius of the corner.

[0078] Based on the sixth embodiment, in the rotor of the eighth embodiment of this disclosure, the second protrusion has a notch in the radial direction orthogonal to the axis of rotation.

[0079] The electric motor of the ninth aspect of this disclosure includes: a rotor of any one of the first to eighth aspects; and a stator configured to be opposite to the rotor and generating a magnetic force acting on the rotor.

[0080] Industrial availability

[0081] The rotor and motor disclosed herein can be widely used in motors used in various equipment, including household electrical appliances and industrial equipment.

[0082] Explanation of reference numerals in the attached figures

[0083] 1. Electric motor; 2. Rotor; 3. Stator; 3a. Stator core; 3a1. Tooth; 3b. Winding coil; 10. Rotating shaft; 20. Rotor core; 21. Magnet mounting hole; 21a. First inner surface; 21b. Second inner surface; 22. First protrusion; 30. Permanent magnet; 30a. Second protrusion; 30b. Covering layer.

Claims

1. A rotor, wherein, The rotor has the following features: The rotor core has multiple magnet mounting holes; Multiple permanent magnets are disposed inside each of the multiple magnet mounting holes; and A rotating shaft, fixed to the rotor core, has a center and rotates about the center along a predetermined direction. The magnet mounting holes each have a first inner surface and a second inner surface opposite to each other in the rotational direction, and a first protrusion is partially present on the first inner surface. The permanent magnets each have a second protrusion facing the first inner surface where the first protrusion is located. The first protrusion and the second protrusion are located near the opposite openings of the magnet configuration hole along the axis.

2. The rotor according to claim 1, wherein, The surface of the first protrusion opposite to the second protrusion is arc-shaped.

3. The rotor according to claim 1, wherein, In the direction of rotation, the size of the first protrusion is larger than the size of the second protrusion.

4. The rotor according to claim 3, wherein, In the direction of rotation, the dimension between the first protrusion and the second inner surface is smaller than the thickness dimension of the permanent magnet.

5. The rotor according to claim 3, wherein, In the direction of rotation, the combined thickness of the permanent magnet and the second protrusion is approximately the same as or smaller than the dimension between the first inner surface and the second inner surface.

6. The rotor according to claim 3, wherein, The permanent magnet is in contact with the second inner surface, and the second protrusion is in contact with the first inner surface.

7. The rotor according to claim 6, wherein, When viewed from the axial direction of the rotating shaft, the corner of the magnet mounting hole connected to the first inner surface is arc-shaped, and the outer circumferential surface of the corner of the second protrusion has a larger radius (R) than that of the corner.

8. The rotor according to claim 6, wherein, The second protrusion has a notch in the radial direction orthogonal to the axis of rotation.

9. An electric motor, wherein, The electric motor comprises: a rotor according to any one of claims 1 to 8; and a stator configured opposite to the rotor and generating a magnetic force acting on the rotor.

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