Rotor and electric motor

Abstract

The present application relates to a rotor and an electric motor. The rotor includes a plurality of magnets supported by a rotor core, and an end plate disposed so as to sandwich end faces of both sides of the rotor core. The end plate is formed of a material having magnetism. The end plate includes a notch portion having a shape in which a surface of the end plate is distanced from an end face of the magnet. The notch portion is formed in a region opposite the magnet.

Description

Technical Field

[0001] The present invention relates to a rotor having an end plate disposed on the end face of a rotor core and an electric motor having the rotor. Background Technology

[0002] An electric motor has a rotor that rotates about a rotation axis and a stator disposed around the rotor. In conventional rotors, it is known that there is a structure including a shaft extending along the rotation axis, a rotor core fixed to the shaft, and magnets fixed to the rotor core.

[0003] It is known that end plates are disposed on both end faces in the direction of extension of the rotation axis of the rotor core. The end plates are formed to clamp the two end faces of the rotor core in the axial direction. Such end plates are fixed by fastening members such as bolts (for example, see Japanese Patent Application Publication No. 2006-238531 and Japanese Patent Application Publication No. 2012-120422). Summary of the Invention

[0004] Multiple magnets fixed to the rotor core are configured, for example, with their outer surfaces alternately forming N and S poles. For the motor to rotate efficiently, it is preferable that the magnetic flux emanating from the N pole of one magnet's outer surface passes through the stator core of the stator and is directed towards the S pole of another magnet. That is, it is preferable that the magnetic field lines travel from the outer surface of one magnet through the stator core towards the surface of another magnet.

[0005] Here, end plates located on both sides of the rotor core along its axial direction contact the end faces of the magnets fixed to the rotor core. Furthermore, the end plates are positioned with a small gap between them and the magnets. When the end plates are made of a magnetic material, magnetic field lines extending from the N pole of one magnet pass through the end plates towards the S pole of the same magnet. A problem arises where loops of magnetic field lines form between the N and S poles of a magnet, causing magnetic flux leakage. This leakage reduces the magnetic force that contributes to the torque generated by the motor. Moreover, the formation of loops of magnetic field lines passing through the end plates leads to overheating of the end plates and iron losses.

[0006] Therefore, in conventional technologies, the end plates sandwiching the rotor core are made of non-magnetic materials. For example, the rotor end plates are made of stainless steel or aluminum. However, stainless steel or aluminum are expensive materials compared to magnetic materials such as iron, resulting in high rotor prices.

[0007] A rotor according to one disclosed technical solution comprises: a rotor core that rotates about a rotation axis; a plurality of magnets supported by the rotor core; and an end plate disposed such that it clamps the end faces of both sides of the rotor core. The end plate is formed of a magnetic material. The end plate includes a recessed portion formed in at least a portion of a region opposite to the magnets, and has a shape in which the surface of the end plate is away from the end face of the magnets. The recessed portion includes at least one of a notch and a recess, the notch being formed at a radial end of the end plate, and the recess being recessed relative to the portion of the end plate that contacts the rotor core.

[0008] The electric motor of the present disclosure has the above-described rotor and a stator in which the rotor is internally arranged. Attached Figure Description

[0009] Figure 1 This is a schematic cross-sectional view of the electric motor in the embodiment of the embodiment, which is cut along a plane parallel to the axis of rotation.

[0010] Figure 2 This is a three-dimensional view of the rotor core, magnets, and end plates of the first rotor.

[0011] Figure 3 This is an exploded three-dimensional view of the rotor core, magnets, and end plates of the first rotor.

[0012] Figure 4 It is a three-dimensional view of the rotor core, magnets and end plates when a portion of the first rotor is cut out.

[0013] Figure 5 This is a three-dimensional view of the end plate of the first rotor.

[0014] Figure 6 This is an enlarged sectional view of the rotor core, magnets, and end plates of the first rotor.

[0015] Figure 7 This is a cross-sectional view illustrating the manufacturing method of the first rotor.

[0016] Figure 8 This is a perspective view of the end plate of the second rotor in the embodiment.

[0017] Figure 9 This is an enlarged top view of the end plate of the second rotor.

[0018] Figure 10 This is an enlarged cross-sectional view of the rotor core, magnet, and end plate of the third rotor in the embodiment.

[0019] Figure 11 This is a perspective view of the end plate of the fourth rotor in the embodiment.

[0020] Figure 12 This is an enlarged sectional view of the rotor core, magnets, and end plates of the fourth rotor.

[0021] Figure 13 This is a perspective view of the end plate of the fifth rotor in the embodiment.

[0022] Figure 14 This is an enlarged top view of the end plate of the 5th rotor. Detailed Implementation

[0023] Reference Figures 1 to 14 The rotor and motor of the embodiment will be described. Figure 1 The diagram shows a schematic cross-sectional view of the electric motor 2 of this embodiment, with the first rotor cut along a plane parallel to the axis of rotation. The electric motor 2 of this embodiment includes a rotor that rotates about a rotation axis 51 and a stator 6 in which the rotor is internally disposed. Figure 1 In the example shown, a first rotor 1 is configured.

[0024] The first rotor 1 includes a shaft 11 that rotates about a rotation axis 51. The shaft 11 is cylindrical. The stator 6 includes, for example, a stator core on which multiple electromagnetic steel plates are stacked in the direction of extension of the shaft 11. The stator 6 includes multiple coils supported by the stator core and arranged circumferentially. The stator 6 is fixed to the housing 3. The shaft 11 is supported by bearings 4 and 5. The bearings 4 and 5 are supported by the housing 3.

[0025] exist Figure 2 The diagram shows a perspective view of the rotor core, magnets, and end plates of the first rotor of this embodiment. Figure 3 An exploded perspective view of the rotor core, magnet, and end plate of the first rotor of this embodiment is shown. (Refer to...) Figures 1-3 In this embodiment, the first rotor 1 is a surface magnet type rotor in which a magnet 13 is disposed on the surface of the rotor core 12.

[0026] The first rotor 1 includes a rotor core 12 fixed to a shaft 11. In this embodiment, the rotor core 12 includes a cylindrical portion 12a having a cylindrical shape. The rotor core 12 rotates about a rotation axis 51. The rotor core 12 in this embodiment is formed from a single magnetic component. For example, the rotor core 12 can be formed by cutting a component primarily composed of iron. The structure of the rotor core is not limited to this form. The rotor core may, for example, be a laminated body consisting of multiple electromagnetic steel plates stacked in the direction extending along the rotation axis.

[0027] The first rotor 1 includes a plurality of magnets 13 supported by a rotor core 12. The plurality of magnets 13 are disposed on the outer peripheral surface of the rotor core 12. In this embodiment, the magnets 13 are permanent magnets formed in a plate shape. The plurality of magnets 13 are arranged at certain intervals along the circumferential direction. The number of magnets depends on the number of poles of the rotor. Any number of magnets can be fixed to the rotor core according to the number of poles of the rotor.

[0028] The magnet 13 extends from one end to the other along the extension direction of the rotation axis 51 of the rotor core 12. The length of the magnet 13 in the extension direction of the rotation axis 51 is less than the length of the rotor core 12. Multiple magnets 13 are configured, for example, with N poles and S poles repeating circumferentially on the outer surface.

[0029] The rotor core 12 has a locking portion 12b extending along the rotation axis 51. The locking portion 12b is formed to protrude radially outward from the cylindrical portion 12a. The locking portion 12b is formed to extend from one end face to the other end face along the extending direction of the rotation axis 51 of the rotor core 12. The locking portion 12b is formed to contact the side of the magnet 13. The locking portion 12b is formed to clamp the magnet 13 in the circumferential direction. The magnet 13 is disposed between the two locking portions 12b. In this embodiment, the magnet 13 is fixed to the rotor core 12 using an adhesive. Alternatively, the magnet 13 may be fixed to the rotor core 12 by being clamped by the two locking portions 12b without using an adhesive. Furthermore, when the magnet 13 is fixed to the rotor core 12 using an adhesive, the movement of the magnet 13 in the circumferential direction can be suppressed by the adhesive. Therefore, it is also possible not to form a locking portion 12b for clamping the magnet 13 in the rotor core 12.

[0030] The first rotor 1 of this embodiment has two end plates 14 arranged such that they hold the end faces on both sides in the extension direction of the rotation axis 51 of the rotor core 12. Each end plate 14 is formed in an annular shape corresponding to the cross-sectional shape of the rotor core 12. Each end plate 14 has a hole 14c through which the shaft 11 passes. Furthermore, in this embodiment, the end plates are arranged in the direction indicated by arrow 61 (…). Figure 2 The end plate 14 (located on the lower side) is referred to as the end plate on one side and will be positioned opposite to arrow 61. Figure 2 The end plate 14 on the upper side is called the end plate on the other side.

[0031] exist Figure 4 The image shows a perspective view of the rotor core, magnet, and end plate of the first rotor of this embodiment, cut across. (Refer to...) Figures 2-4 The two end plates 14 are fixed to each other by bolts 31, which serve as fastening components. The bolts 31 are arranged at certain intervals along the circumference.

[0032] In configuration Figure 2 , Figure 3 and Figure 4 The lower end plate 14 has a hole 26 formed on one side, and the hole 26 has threads for fixing the bolt 31. A through hole 12c is formed in the cylindrical portion 12a of the rotor core 12 for the bolt 31 to pass through. In a configuration... Figures 2-4 The end plate 14 on the other side of the upper side has an insertion portion 25 for supporting the head of the bolt 31. The hole 26, the through hole 12c and the insertion portion 25 are formed in a position where they communicate with each other.

[0033] The method of fixing the end plate 14 to the rotor core 12 is not limited to the method of fixing with bolts 31, and any method can be used. For example, the end plate can be fixed to the rotor core by welding, bonding, heat fitting to the inner circumferential surface of the rotor core, or pressing into the inner circumferential surface of the rotor core. In addition, sometimes the rotor core is not formed by a laminate of electromagnetic steel sheets, but by cutting an iron component. In this case, the bolt does not need to penetrate the rotor core, and a threaded hole with a bottom can be formed in the rotor core. Moreover, the bolt can be fixed in the threaded hole.

[0034] exist Figure 5 A perspective view of the end plate according to this embodiment is shown. Figure 5 The diagram shows one of the two end plates 14. As described above, an insertion portion 25 is formed on the other end plate 14 instead of a hole portion 26. A notch portion 14a, identical to that on the other end plate 14, is also formed on the other end plate 14. The other structure of the other end plate 14 is the same as that of the other end plate 14.

[0035] exist Figure 6 The image shows an enlarged sectional view of the rotor core, magnets, and end plates, taken at the point where the bolts penetrate the first rotor. (Refer to...) Figure 5 and Figure 6 In this embodiment, the end plate 14 is formed of a magnetic material. For example, the end plate 14 is formed of a material whose main component is iron, such as carbon steel.

[0036] The end plate 14 has a notch 14a formed on the surface in contact with the rotor core 12, serving as a retraction portion. The retraction portion has a shape in which a space is formed on the side of the end face 13a of the magnet 13. Furthermore, the retraction portion has a shape in which the surface of the end plate 14 is away from the end face 13a of the magnet 13. The retraction portion is formed in at least a portion of the region opposite to the magnet 13. In the first rotor 1, the notch 14a is formed on the outer periphery of the end plate 14 in the radial direction. In particular, the notch 14a is formed throughout the entire outer periphery. The notch 14a is formed to extend circumferentially along the end plate 14.

[0037] Furthermore, in this embodiment, the length of the magnet 13 is slightly shorter than the length of the rotor core 12 in the extending direction of the rotation axis 51. The end plate 14 contacts the end face of the rotor core 12, thereby pressing down on the rotor core 12. If the end plate 14 contacts the magnet 13, there is a possibility that the end plate 14 presses down on the magnet 13 in the direction that clamps the magnet 13. As a result, the magnet 13 may break. Therefore, in the first rotor 1 of this embodiment, the magnet 13 is formed to be shorter so that it is not pressed down by the end plate 14.

[0038] The first rotor 1 is formed such that the radial length of the notch 14a is shorter than the maximum radial thickness of the magnet 13. The end plate 14 has a support portion 14b formed opposite to the magnet 13. The support portion 14b is close to the end face 13a of the magnet 13. The support portion 14b is formed to contact the magnet 13 and support it when the magnet 13 moves along the extension direction of the rotation axis 51. The support portion 14b is formed in the region surrounding the notch 14a. In the first rotor 1, the support portion 14b is formed in the region radially inward of the notch 14a. Furthermore, in this embodiment, the magnet 13 is fixed to the rotor core 12 using an adhesive. A small gap is formed between the support portion 14b of the end plate 14 and the end face 13a of the magnet 13.

[0039] In this embodiment, the end plate 14 is formed of a magnetic material. Therefore, it is not necessary to use expensive materials such as stainless steel or aluminum. On the other hand, there is a situation where the magnetic flux of the magnet 13 leaks when the end face 13a of the magnet 13 approaches or contacts the magnetic end plate 14 with a large area. That is, there is a situation where a loop of magnetic field lines is formed in a magnet 13 through the interior of the end plate 14.

[0040] In the first rotor 1 of this embodiment, a notch 14a is formed as a retraction portion to create a space between the magnet 13 and the end plate 14. The notch 14a allows the surface of the end plate 14 to be moved away from the end face 13a of the magnet 13. Therefore, it is possible to suppress the formation of loops of magnetic field lines on a single magnet. The motor equipped with the rotor of this embodiment can suppress the reduction in torque caused by magnetic flux leakage.

[0041] Thus, in the rotor of this embodiment, the use of expensive materials can be avoided and magnetic flux leakage can be suppressed. As a result, an inexpensive rotor and motor with excellent performance can be provided.

[0042] exist Figure 7 The diagram shows an enlarged cross-sectional view of the rotor core, magnet, and end plate illustrating the manufacturing method of the first rotor according to this embodiment. The operator places the rotor core 12 on one side of the end plate 14. At this time, the rotor core 12 is arranged such that a through hole 12c formed in the rotor core 12 communicates with a hole 26 formed in one side of the end plate 14. The rotor core 12 and the end plate 14 are temporarily fixed using a fixture such as a fastener.

[0043] Next, the operator applies adhesive 35 to the area between the locking portions 12b of the rotor core 12. Then, the operator positions the magnet 13 between the locking portions 12b. The operator moves the magnet 13 as indicated by arrow 62, thereby inserting the magnet 13 between the locking portions 12b. Adhesive 35 is disposed between the magnet 13 and the outer peripheral surface of the rotor core 12. Excess adhesive 35 is extruded by the magnet 13 into the notch 14a as indicated by arrow 63. Afterward, the other end plate 14 is positioned, and the two end plates 14 are secured to the rotor core 12 using bolts 31.

[0044] In conventional technology, since no notch 14a is formed in the end plate 14, excess adhesive overflows outward from the boundary between the magnet and the end plate. The operator needs to wipe away the adhesive overflowing from the boundary between the magnet and the end plate. In contrast, in the first rotor of this embodiment, excess adhesive 35 moves towards the notch 14a as shown by arrow 63. This prevents excess adhesive 35 from overflowing outward. Therefore, the operation of wiping away excess adhesive is unnecessary. Furthermore, the operation of shaving off excess adhesive after it dries is also unnecessary.

[0045] Furthermore, when a large amount of adhesive 35 is applied, there is a situation where, when the magnet 13 is inserted between the locking portions 12b, the adhesive 35 protrudes radially outward from the notch 14a. In this case, the operator can also wipe or shave off the adhesive 35. In this case, by forming the notch 14a, the amount of adhesive protruding from the notch 14a can be reduced, thus simplifying the operator's work.

[0046] Reference Figure 6 In this embodiment, the end plate 14 has a support portion 14b, which is formed in a region radially inward than the notch portion 14a and faces the magnet 13. When the adhesive 35 detaches from the magnet 13, the magnet 13 moves along the rotation axis 51. The support portion 14b is formed to contact the magnet 13 and support it during movement. Therefore, even if the adhesive 35 detaches from the magnet 13, movement of the magnet 13 in the direction of the rotation axis 51 can be suppressed. In particular, protrusion of the magnet 13 from the end face of the rotor core 12 can be suppressed.

[0047] Furthermore, in this embodiment, the magnet 13 is fixed to the rotor core 12 using adhesive 35, but this configuration is not limited to this form. The magnet 13 may also be fixed to the rotor core 12 without adhesive 35. The magnet 13 may also be configured to move slightly along the extension direction of the rotation axis 51. Even in this case, since the end plate 14 has a support portion 14b, it is possible to prevent the magnet 13 from moving and protruding from the end face of the rotor core 12. In addition, in this embodiment, the end face 13a of the magnet 13 is slightly separated from the support portion 14b of the end plate 14, but this configuration is not limited to this form. Alternatively, the end plate 14 may be fastened using bolts 31, thereby bringing the end face 13a of the magnet 13 into contact with the support portion 14b of the end plate 14.

[0048] exist Figure 8 The diagram shows an enlarged perspective view of the end plate of the second rotor according to this embodiment. The end plate 14 of the first rotor 1 has a notch 14a formed throughout its outer periphery, but is not limited to this form. The notch 14a, serving as a retraction portion, may also be formed in at least a portion of the area where the magnet 13 is disposed. The second rotor has two end plates 15. Each end plate 15 has a plurality of notches 15a. The notches 15a are formed circumferentially along the outer periphery of the end plate 15.

[0049] exist Figure 9 The image shows an enlarged top view of the end plate of the second rotor in this embodiment. Figure 9 The region 41 where the magnet 13 is disposed is shown in dashed lines. (See reference...) Figure 8 and Figure 9 The notch 15a is formed to correspond to the area where the magnet 13 is disposed. The circumferential length of the notch 15a is shorter than the circumferential length of the magnet 13. A support portion 15b is formed in the area surrounding the notch 15a, opposite to the magnet 13. Alternatively, the circumferential length of the notch 15a may be the same as the circumferential length of the magnet 13. Furthermore, the circumferential length of the notch 15a may be longer than the circumferential length of the magnet 13.

[0050] In the second rotor, the space formed by the notch 15a can also be used to suppress magnetic flux leakage. Since other structures, functions, and effects are the same as in the first rotor, they will not be repeated here.

[0051] exist Figure 10The diagram shows an enlarged cross-sectional view of the rotor core, magnet, and end plates of the third rotor according to this embodiment. The third rotor includes two end plates 16 disposed on both sides of the rotor core 12. The magnet 13 is fixed to the rotor core 12 using an adhesive. A notch 16a is formed on the outer periphery of the end plate 16. The radial length of the notch 16a is longer than the radial length of the magnet 13. No support portion is formed on the end plate 16 opposite to the end face 13a of the magnet 13. The magnet 13 is disposed inside the region where the notch 16a is formed. The notch 16a is formed such that the entire end face 13a of the magnet 13 is separated from the surface of the end plate 16.

[0052] By adopting the structure of the notch 16a in the third rotor, the space formed on the side of the end face 13a of the magnet 13 is increased, thereby increasing the effect of suppressing magnetic flux leakage of the magnet 13. The other structures, functions, and effects of the third rotor are the same as those of the first and second rotors, and therefore will not be repeated here.

[0053] In the first, second, and third rotors described above, a notch is formed on the outer periphery of the end plate, but this is not limited to this configuration. The notch can be formed at the radial end of the end plate. For example, the notch can also be formed on the inner periphery of the end plate. That is, the notch can also be formed from the inner peripheral surface of the end plate toward the radially outer side.

[0054] exist Figure 11 The image shows a perspective view of the end plate of the fourth rotor in this embodiment. Figure 12 The image shows an enlarged cross-sectional view of the rotor core, end plate, and magnet of the fourth rotor of this embodiment. (Refer to...) Figure 11 and Figure 12 The fourth rotor includes two end plates 18. Each end plate 18 includes a recess 18a as a recessed portion having a shape that avoids the end face 13a of the magnet 13. The recess 18a is a recessed portion relative to the part of the end plate 18 that contacts the rotor core 12. The recess 18a is formed in the region where the end face 13a of the magnet 13 is disposed. The recess 18a extends circumferentially. The recess 18a is formed such that at least a portion of the end face 13a of the magnet 13 does not contact the end plate 18. Furthermore, the recess 18a is formed such that at least a portion of the end face 13a of the magnet 13 is not close to the end plate 18. In the fourth rotor of this embodiment, the recess 18a is formed by a groove that surrounds the circumference.

[0055] exist Figure 11 The diagram shows the end plate 18 on one side where the hole 26 is formed. For the other end plate 18 on the other side where the insertion portion 25 is formed, a recess 18a, similar to that on one side of the end plate 18, is also formed on the surface that contacts the rotor core 12. In the fourth rotor, at least a portion of the end face 13a of the magnet 13 is in contact with the space formed by the recess 18a, thus suppressing magnetic flux leakage.

[0056] Furthermore, during the rotor manufacturing process, when the magnets are positioned between the locking parts, excess adhesive is squeezed into the interior of the recess 18a. Since the recess 18a is not connected to the outer peripheral surface, it is possible to prevent excess adhesive from protruding to the outside of the rotor. Therefore, the work of wiping or shaving off excess adhesive can be reduced.

[0057] In this embodiment, the end plate 18 has a support portion 18b, which is formed opposite to the end face 13a of the magnet 13. The support portion 18b is formed in the area surrounding the recess 18a. The end plate 18 having the support portion 18b can suppress movement of the magnet 13 along the extension direction of the rotation axis 51. In particular, when the magnet 13 is not fixed by adhesive, it can suppress the magnet 13 from protruding from the end face of the rotor core 12.

[0058] Additionally, the fourth rotor has a support portion 18b opposite to the end face of the magnet 13, but is not limited to this configuration. A recess may also be formed in the end plate without the support portion. For example, the entire end face of the magnet may be positioned inside the recessed area. That is, the recess may be formed to be large enough that the end face of the magnet is positioned inside the recessed area.

[0059] The other structures, functions, and effects of the fourth rotor are the same as those of the first to third rotors, so they will not be repeated here.

[0060] exist Figure 13 The diagram shows a perspective view of the end plate of the fifth rotor according to this embodiment. Multiple recesses 19a are formed on the end plate 19 of the fifth rotor as recesses. The multiple recesses 19a are formed separately from each other in a manner corresponding to the regions of the magnet 13. The recesses 19a are formed along the circumferential direction. Figure 13 The end plate 19 on one side, which has a hole 26, is shown. The end plate 19 on the other side, which has an insertion portion 25, has the same recess 19a as the end plate 19 on one side.

[0061] exist Figure 14 The image shows a top view illustrating the area of ​​the fifth rotor where multiple recesses are formed and the area where magnets are arranged. Figure 14 In the diagram, the region 41 where the magnet 13 is disposed is shown in dashed lines. Each recess 19a is formed corresponding to the region 41 where the magnet is disposed. Furthermore, in this example, one recess 19a is formed relative to each magnet 13.

[0062] The radial length of the recess 19a is smaller than the maximum radial thickness of the magnet 13. Furthermore, the circumferential length of the recess 19a is smaller than the circumferential length of the magnet 13. The support portion 19b of the end plate 19 is composed of a circumferential lateral portion and a radial lateral portion of the recess 19a within the region 41 where the magnet is disposed. The end plate 19 includes the support portion 19b, thereby suppressing movement of the magnet along the extension direction of the rotation axis 51.

[0063] The other structures, functions, and effects of the fifth rotor are the same as those of the first to fourth rotors, so they will not be repeated here.

[0064] In the fourth and fifth rotors of this embodiment, recesses extending circumferentially are formed in the end plates, but the embodiment is not limited to this form. The recesses can be formed in at least a portion of the region opposite the magnet. For example, dot-shaped recesses can also be formed in the region where the magnet is disposed.

[0065] In the end plate of the above-described embodiment, a recessed portion, either a notch or a recess, is formed, but the embodiment is not limited to this configuration. At least one of the notch and recess can be formed in the end plate. For example, notches and recesses can be alternately formed circumferentially in one end plate. Furthermore, a notch can be formed on one side of the end plate, and a recess can be formed on the other side.

[0066] The rotor of this embodiment is a surface magnet type rotor in which multiple permanent magnets are arranged circumferentially on the outer peripheral surface of the rotor core, but it is not limited to this form. It is also possible to arrange the end plate with the retractable part of this embodiment in a rotor in which permanent magnets are embedded inside the rotor core.

[0067] The technical solution disclosed herein can provide a rotor having magnetic end plates that suppress magnetic flux leakage and an electric motor having the rotor.

[0068] The above-described embodiments can be appropriately combined. In the above figures, the same or equivalent parts are labeled with the same reference numerals. Furthermore, the above-described embodiments are illustrative and do not limit the invention. In addition, modifications to the embodiments shown in the claims are included in the embodiments.

Claims

1. A rotor, wherein, The rotor has the following features: The rotor core rotates about its axis of rotation. Multiple magnets, supported by the rotor core and disposed on the outer peripheral surface of the rotor core; and End plates, which are arranged to clamp the end faces of both sides of the rotor core. The end plate is formed of a magnetic material. The end plate includes a recessed portion formed in at least a portion of the region opposite the magnet, and has a shape in which the surface of the end plate is away from the end face of the magnet. The retraction portion includes a notch that is formed radially at the end of the end plate in contact with the rotor core, extending throughout the entire outer periphery. Air exists in the space formed by the notch and the end face of the magnet. The end plate has a support portion that is opposite to the magnet and supports the magnet when the magnet moves along the extension direction of the rotation axis. The support portion forms the area surrounding the recessed portion.

2. The rotor according to claim 1, wherein, The magnet is fixed to the rotor core using an adhesive.

3. An electric motor, wherein, This electric motor has the following features: The rotor as claimed in claim 1; and The stator, in which the rotor is arranged.

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