Rotor, motor, and electronic apparatus

Abstract

To provide a rotor which can increase a detent torque.SOLUTION: The rotor includes: a magnet body having two magnetic pole parts, a ring part, and two connection parts connecting the two magnetic parts and the ring part together; and a magnet between the two magnetic pole parts in a circumferential direction. In a side surface extending in the circumferential direction of the two magnetic pole parts, at least one recessed part or at least one protruding part is formed.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a rotor, a motor, and an electronic device. [Background technology]

[0002] Among inner rotor type motors, there is one in which the rotor is provided with multiple magnets and a magnetic body formed by laminating thin metal plates, and the magnetic body is formed into a spoke shape (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2013-529054 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional rotors have room for improvement in terms of increasing detent torque.

[0005] The present invention has been made in view of the above, and has an object to provide a rotor, a motor, and an electronic device that are capable of increasing detent torque. [Means for solving the problem]

[0006] In one embodiment, the rotor comprises a magnetic body having two magnetic pole portions, an annular portion, and two connecting portions connecting the two magnetic pole portions and the annular portion, and a magnet located between the two magnetic pole portions in the circumferential direction, and one or more recesses or one or more protrusions are formed on the side surfaces of the two magnetic pole portions extending in the circumferential direction.

[0007] According to one aspect, the detent torque can be increased. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of an electronic device according to an embodiment. [Figure 2] FIG. 2 is an exploded perspective view of a motor included in the electronic device shown in FIG. [Figure 3] FIG. 3 is a perspective view of the magnetic body and magnet of the rotor included in the motor shown in FIG. [Figure 4] FIG. 4 is a front view of the magnetic body and the magnet shown in FIG. [Figure 5] FIG. 5 is an enlarged view of a portion of FIG. [Figure 6] FIG. 6 is a cross-sectional view of the rotor shown in FIG. [Figure 7] FIG. 7 is a perspective view of a magnetic body included in the rotor shown in FIG. [Figure 8] FIG. 8 is an enlarged view of a portion of FIG. [Figure 9] FIG. 9 is an enlarged view of a magnetic pole portion of a stator included in the motor shown in FIG. [Figure 10] FIG. 10 is a plan view of the recesses and protrusions of the magnetic pole portions of the rotor and the recesses and protrusions of the magnetic pole portions of the stator. [Figure 11] FIG. 11 is an enlarged view of the recesses and protrusions of the magnetic pole portions of the rotor and the recesses and protrusions of the magnetic pole portions of the stator. [Figure 12] FIG. 12 is a diagram showing the flow of magnetic flux from the magnet of the rotor relative to the stator and the magnitude of the magnetic flux density when the magnetic body of the rotor and the teeth of the stator face each other. [Figure 13] FIG. 13 is a diagram showing the waveform of the cogging torque in the state shown in FIG. [Figure 14] Figure 14 shows the flow of magnetic flux from the rotor's magnet relative to the stator and the magnitude of the magnetic flux density when the rotor rotates slightly circumferentially from a state in which the rotor's magnetic material and the stator's teeth are facing each other to a non-facing state. [Figure 15] FIG. 15 is a diagram showing the waveform of the cogging torque in the state shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Embodiment] The motor 1, rotor 4, and electronic device 300 according to the embodiment will be described in detail below with reference to the drawings. Note that the dimensional relationships and ratios of elements in the drawings may differ from the actual situation. The dimensional relationships and ratios may also differ between the drawings.

[0010] The motor 1 of this embodiment is housed in an electronic device 300 as shown in Fig. 1, for example. Fig. 1 is a perspective view of the electronic device 300 according to this embodiment. In explaining the motor 1 according to this embodiment, to facilitate understanding of directions, the direction in which the shaft 2 extends is referred to as the axial direction A, the direction in which the rotor 4 rotates is referred to as the circumferential direction C, and the direction that is included in a plane perpendicular to the axial direction A, passes through the axis 2o of the shaft 2, and is perpendicular to the circumferential direction C is referred to as the radial direction R.

[0011] The electronic device 300 is a device mounted on a vehicle such as an electric vehicle or a hybrid vehicle, and includes, for example, a motor 1, a housing 301 that houses the motor 1, a first gear 302, and a second gear 303.

[0012] The first gear 302 is, for example, a worm gear, and rotates in conjunction with the shaft 2 of the motor 1. The second gear 303 is, for example, a helical gear that meshes with the first gear 302, and rotates in conjunction with the output shaft 304. With this configuration, the driving force of the shaft 2 of the motor 1 is transmitted to the output shaft 304 of the electronic device 300.

[0013] Next, motor 1 will be described with reference to Figures 1 and 2. Figure 2 is an exploded perspective view of motor 1 provided in electronic device 300 shown in Figure 1. Motor 1 in this embodiment includes a shaft 2, a stator 3, and a rotor 4. Note that motor 1 according to this embodiment is an inner rotor brushless motor in which, for example, stator 3 is located outside rotor 4 in the radial direction R.

[0014] The shaft 2 is a so-called rotating shaft, and is formed, for example, in the shape of a column or cylinder using a metal material, and extends along the axial direction A. The shaft 2 has an axial center 2o, and is provided so as to be rotatable about the axial center 2o in the circumferential direction C relative to the electronic device 300. A first gear 302 is fixed to one end of the shaft 2 in the axial direction A.

[0015] The stator 3 is a part that generates a force for rotating the rotor 4 in the circumferential direction C. The stator 3 includes a yoke 31 as an annular part, teeth 32 as magnetic pole portions 30, coils 33, and insulators 34. The stator 3 according to this embodiment is composed of electrically non-connected members. The yoke 31 and teeth 32 are made of a magnetic material (see FIG. 9).

[0016] The yoke 31 is formed in an annular shape and located outside the stator 3 in the radial direction R. The teeth 32 protrude inward in the radial direction R from the inner peripheral surface of the yoke 31. The yoke 31 and the teeth 32 are formed by punching out flat plate-shaped members made of a magnetic material (magnetic substance) such as an electromagnetic steel plate, and stacking multiple members in the axial direction A. The coils 33 are wound around the teeth 32, for example, via insulators 34.

[0017] Next, the rotor 4 will be described. The rotor 4 is rotatably disposed inside the stator 3 in the radial direction R. The rotor 4 includes a magnetic body 41 having at least two magnetic pole portions 411, a plurality of magnets 42, and a pair of covers 43. The rotor 4 according to this embodiment is a so-called IPM (Interior Permanent Magnet) rotor, which is configured with a plurality of magnets 42 arranged such that two adjacent magnets 42 repel each other in the circumferential direction C, and a magnetic body 41 housing the plurality of magnets 42, and the plurality of magnets 42 are arranged radially. The outer size (outer diameter D0) of the rotor 4 according to this embodiment is, for example, 24.5 mm (see FIG. 4).

[0018] The magnetic body 41 provided in the rotor 4 will be described in detail later, and next, the magnet 42 will be described using Figures 3, 4, and 5. Figure 3 is a perspective view of the magnetic body 41 and magnet 42 of the rotor 4 provided in the motor 1 shown in Figure 2. Figure 4 is a front view of the magnetic body 41 and magnet 42 shown in Figure 3. Figure 5 is an enlarged view of a portion of Figure 4. The multiple magnets 42 are arranged at equal intervals in the circumferential direction C, for example. The magnet 42 in this embodiment is a permanent magnet extending in the axial direction A, for example. The magnet 42 is also a sintered magnet, for example. The magnet 42 is located between two magnetic pole portions 411 in the circumferential direction C. The magnet 42 is formed in a substantially rectangular shape when viewed from the axial direction A.

[0019] The magnet 42 has an inner end face (inner face) 421 in the radial direction R, an outer end face (outer face) 422 in the radial direction R, and side faces 423, 424 in the circumferential direction C. In the embodiment, the width W1 (see FIG. 4) of the magnet 42 in the circumferential direction C shown in FIG. 4 is, for example, an outer diameter of 2.29 mm, and the magnet length (length in the radial direction R) L1 (see FIG. 4) of the magnet 42 is, for example, 3.50 mm.

[0020] In this embodiment, two magnets 42 adjacent to each other in the circumferential direction C via a magnetic pole portion 411 are arranged so that the same poles face each other. For example, as shown in Fig. 5, two magnets 42 adjacent to each other in the circumferential direction C are arranged so that the N poles face each other.

[0021] Next, the pair of covers 43 will be described with reference to Figures 2 and 6. Figure 6 is a cross-sectional view of the rotor 4 shown in Figure 3. The cover 43 according to this embodiment is made of a non-magnetic material, such as brass, or a material with lower magnetic permeability than the magnetic body 41. The cover 43 may also be formed by bending a material with lower magnetic permeability than the electromagnetic steel sheet that makes up the magnetic body 41, such as austenitic stainless steel.

[0022] One cover 43a of the pair of covers 43 is attached to the magnetic body 41 from one side in the axial direction A, and the other cover 43b of the pair of covers 43 is attached to the magnetic body 41 from the other side in the axial direction A. In other words, the pair of covers 43 are arranged to sandwich the magnetic body 41 in the axial direction A.

[0023] In the pair of covers 43, the configuration of one cover 43a and the configuration of the other cover 43b are the same, but they may also have different configurations and are not limited thereto. Therefore, in the following, the configuration of one cover 43a will be described, and the configuration of the other cover 43b will be assigned the same reference numerals as the one cover 43a and will not be described again.

[0024] One cover 43a has a main body portion 431 formed in the shape of a flat ring, a plurality of outer peripheral portions 432 protruding in the axial direction A from the main body portion 431 at its outer peripheral edge in the radial direction R, and an inner peripheral portion 433 protruding in the axial direction A from the main body portion 431 at its inner peripheral edge in the radial direction R.

[0025] Each of the outer peripheral portions 432 protrudes from the outer peripheral edge of the main body portion 431 toward the outer peripheral portion 432 of the other cover 43b in the axial direction A. The multiple outer peripheral portions 432 are arranged, for example, at predetermined intervals (e.g., equal intervals) in the circumferential direction C. Furthermore, as shown in FIG. 6 , the outer peripheral portions 432 are arranged at positions facing the outer end faces 422 of the magnets 42 in the radial direction R. In the radial direction R of the rotor 4 according to this embodiment, a small gap is formed between the outer end faces 422 of the magnets 42 and the inner surfaces of the outer peripheral portions 432, but the outer end faces 422 of the magnets 42 may also come into contact with the inner surfaces of the outer peripheral portions 432. Furthermore, in this embodiment, the number of the multiple outer peripheral portions 432 is the same as the number of magnets 42.

[0026] The outer peripheral portion 432 is disposed outside the magnet 42 so as to be able to come into contact with the outer end face 422 of the magnet 42 in the radial direction R. Therefore, in the rotor 4 shown in Fig. 4, each cover 43 prevents the magnet 42 from moving outward in the radial direction R due to a repulsive force with other adjacent magnets 42 in the circumferential direction C and a centrifugal force generated by the rotation of the rotor 4.

[0027] 2 and 6, the inner circumferential portion 433 of one cover 43a protrudes from the inner circumferential edge of the main body portion 431 toward the inner circumferential portion 433 of the other cover 43b in the axial direction A. The inner circumferential portion 433 is formed, for example, in a cylindrical shape. Moreover, the inner circumferential portion 433 is disposed so as to face the inner circumferential surface of the annular portion 412.

[0028] The inner circumferential portion 433 is disposed inside the magnet 42 so as to be able to come into contact with the inner end face 421 of the magnet 42 in the radial direction R. Therefore, in the rotor 4 shown in Fig. 4, each cover 43 prevents the magnet 42 disposed on the magnetic body 41 from moving inward in the radial direction R due to a repulsive force with other magnets 42 adjacent thereto in the circumferential direction C, etc.

[0029] Furthermore, the main body 431 of one cover 43a faces (or contacts) one side of the magnet 42 in the axial direction A, and the main body 431 of the other cover 43b faces (or contacts) the magnet 42 on the other side in the axial direction A. With this configuration, movement of the magnet 42 in the axial direction A is suppressed.

[0030] The outer diameter (size) of the inner circumferential portion 433 is, for example, slightly larger than the inner diameter (size) of the second protrusion 415 formed on the magnetic body 41. The inner diameter (size) of the inner circumferential portion 433 is, for example, slightly smaller than the outer diameter (size) of the shaft 2.

[0031] In this configuration, the cover 43 is press-fitted, for example, into the second protruding portion 415 of the magnetic body 41 in the radial direction R. Thereafter, the shaft 2 is press-fitted into the inner circumferential portion 433. That is, in this embodiment, the pair of covers 43, the magnetic body 41, and the shaft 2 form a double press-fit structure.

[0032] Next, the magnetic body 41 included in the rotor 4 will be described with reference to Fig. 4 and Fig. 5. As shown in Fig. 4, the magnetic body 41 has at least two magnetic pole portions 411, an annular portion 412, at least two connection portions 413, a first protrusion 414, and a second protrusion 415. The first protrusion 414 is an example of a protrusion that protrudes from the annular portion 412 in the magnetic body 41.

[0033] The magnetic pole portions 411 are disposed on the outer side of the magnetic body 41 in the radial direction R, and are formed in a substantially fan-like shape when viewed from the axial direction A. More specifically, when viewed from the axial direction A, the magnetic pole portions 411 are formed in a substantially fan-like shape that gradually widens outward in the radial direction R, such that the length of the arc (passing through the two outermost portions of) the outer circumferential surface 4112 away from the axis 2o is longer than the length of the arc (passing through the two innermost portions of) the inner circumferential surface 4111 close to the axis 2o. The magnetic pole portions 411 form the outer circumferential portion of the magnetic body 41. The magnetic body 41 in this embodiment includes, for example, ten magnetic pole portions 411. The multiple magnetic pole portions 411 are arranged, for example, in a line in the circumferential direction C at predetermined intervals (for example, equal intervals).

[0034] As shown in Figure 5, each magnetic pole portion 411 has an inner circumferential surface 4111 located on the inside in the radial direction R, an outer circumferential surface 4112 located on the outside in the radial direction R, and two side surfaces 4113 and 4114 connecting the inner circumferential surface 4111 and the outer circumferential surface 4112.

[0035] The inner circumferential surface 4111 has an end (hereinafter referred to as a tip portion 4111a) that protrudes inward from the magnetic pole portion 411 in the radial direction R. The tip portions 4111a form a part of the inner circumferential surface 4111 of the magnetic pole portion 411, and for example, two tip portions 4111a are formed on the inner circumferential surface 4111. A recessed portion 4111b that forms a part of the inner circumferential surface 4111 of the magnetic pole portion 411 is formed between the two tip portions 4111a.

[0036] The outer peripheral surface 4112 will be described in detail later. Between the outer peripheral surface 4112 and the side surfaces 4113 and 4114, end portions formed by curved surfaces are disposed.

[0037] 4 is disposed on the inner side of the magnetic pole portion 411 in the radial direction R of the magnetic body 41, and is formed in a ring shape when viewed from the axial direction A. The annular portion 412 forms the inner circumferential portion of the magnetic body 41.

[0038] The connecting portion 413 connects the magnetic pole portion 411 and the annular portion 412. The connecting portion 413 is disposed between the magnetic pole portion 411 and the annular portion 412 in the radial direction R, and is formed to extend linearly in the radial direction R. The connecting portion 413 is disposed between the recessed portions 4111b located between the two tip portions 4111a in the circumferential direction C. The magnetic body 41 in this embodiment includes, for example, ten connecting portions 413. The multiple connecting portions 413 are disposed, for example, lined up in the circumferential direction C at equal intervals.

[0039] When viewed from the axial direction A, the first protrusions 414 protrude outward in the radial direction R from the outer circumferential surface of the annular portion 412. The magnet 42 is in contact with the first protrusions 414 in the radial direction R. In the rotor 4 of this embodiment, the first protrusions 414 support the inner end face (inner surface) 421 of the magnet 42 from the inside in the radial direction R. The magnetic body 41 of this embodiment includes, for example, ten first protrusions 414. The multiple first protrusions 414 are arranged, for example, in a line in the circumferential direction C at predetermined intervals (for example, equal intervals).

[0040] When viewed from the axial direction A, the second protrusions 415 protrude inward in the radial direction R from the inner circumferential surface of the annular portion 412. The magnetic body 41 in this embodiment includes, for example, ten second protrusions 415. The multiple second protrusions 415 are, for example, arranged side by side in the circumferential direction C at equal intervals.

[0041] Also, as shown in Figure 5, the magnetic pole portion 411 has a first through hole (hole portion) 411H that penetrates the magnetic pole portion 411 in the axial direction A, and the annular portion 412 has a second through hole (hole portion) 412H that penetrates the annular portion 412 in the axial direction A.

[0042] Next, a manufacturing method of the magnetic body 41 will be described with reference to Fig. 7. Fig. 7 is a perspective view of the magnetic body 41 provided in the rotor 4 shown in Fig. 3. In this embodiment, the magnetic body 41 is made up of a plurality of magnetic members 410 stacked in the axial direction A. The plurality of magnetic members 410 are formed to have, for example, the same shape and size.

[0043] The magnetic members 410 are coupled to one another by first screws N1 inserted through the respective first through holes 411H, and are coupled to one another by second screws N2 inserted through the respective second through holes 412H. The first screws N1 and the second screws N2 are formed of a material, such as stainless steel, that has a lower magnetic permeability than the magnetic body 41. In other words, the first screws N1 and the second screws N2 function as flux barriers.

[0044] 5, the first screw N1 inserted through the first through hole 411H is located in the middle of the magnetic paths M1, M2 that extend from the center of the side surfaces 423, 424 of the magnet 42 in the radial direction R toward the circumferential direction C. The magnetic permeability of the first screw N1 is lower than the magnetic permeability of the magnetic body 41, and therefore the first screw N1 functions as a flux barrier. Therefore, the magnetic flux that extends from the center of the side surfaces 423, 424 of the magnet 42 in the radial direction R toward the circumferential direction C is suppressed, and the magnetic flux that extends from the side surfaces 423, 424 of the magnet 42 toward the outer peripheral surface 4112 on the outside in the radial direction R is increased.

[0045] In addition, the magnetic paths M3 and M4 extending from the inner end face 421 of the magnet 42 in the radial direction R toward the inside of the first protrusion 414 in the radial direction R are narrowed by the second screw N2. This makes it easier for magnetic saturation to occur in the magnetic paths M3 and M4, so that the magnetic flux extending from the inner end face 421 of the magnet 42 toward the inside in the radial direction R is suppressed by the magnetic paths M3 and M4, and the magnetic flux extending from the outer end face 422 of the magnet 42 toward the outer peripheral surface 4112 on the outside in the radial direction R is increased.

[0046] Furthermore, magnetic flux from the inside of the side surfaces 423, 424 of the magnet 42 in the radial direction R flows through the tip portion 4111a of the magnetic pole portion 411 toward the outer peripheral surface 4112 on the outside in the radial direction R. Because the magnetic pole portion 411 is formed in a substantially fan shape when viewed from the axial direction A, magnetic paths M5, M6 extending from the inside of the side surfaces 423, 424 of the magnet 42 in the radial direction R toward the outer peripheral surface 4112 on the outside of the magnetic pole portion 411 gradually widen toward the outside in the radial direction R. Therefore, the magnetic flux extending from the inside of the side surfaces 423, 424 of the magnet 42 in the radial direction R toward the outer peripheral surface 4112 on the outside in the radial direction R is increased.

[0047] Furthermore, recesses 4111b are formed in the inner circumferential surface 4111 of the magnetic pole portion 411, and because the magnetic permeability of the recesses 4111b is lower than that of the magnetic body 41, the air in the recesses 4111b functions as a flux barrier. Therefore, the magnetic paths M5 and M6 that run from the inside in the radial direction R of the side surfaces 423 and 424 of the magnet 42 in the circumferential direction C to the connecting portion 413 via the magnetic pole portion 411 are narrowed by the recesses 4111b, making magnetic saturation more likely to occur. This further suppresses leakage of magnetic flux from the magnet 42 to the annular portion 412 located on the inside in the radial direction R via the magnetic pole portion 411 and the connecting portion 413, and increases the magnetic flux that runs from the side surfaces 423 and 424 of the magnet 42 to the outer circumferential surface 4112 on the outside in the radial direction R. Note that recess 4111b may be filled with air or a non-magnetic material (for example, a resin having a lower magnetic permeability than the magnetic material such as the electromagnetic steel sheet that forms stator 3).

[0048] Furthermore, the outer end face 422 of the magnet 42 is located inside the outer peripheral surface 4112 of the magnetic pole portion 411 in the radial direction R. A space U is formed outside the outer end face 422 of the magnet 42 in the radial direction R and between two adjacent magnetic pole portions 411 in the circumferential direction C. An outer peripheral portion 432 of the cover 43 is disposed in this space U. Because the magnetic permeability of the cover 43 is lower than that of the magnetic body 41, the outer peripheral portion 432 functions as a flux barrier. Therefore, in magnetic paths M7 and M8 extending from the side surfaces 423 and 424 of the magnet 42 toward the outer outer peripheral surface 4112, the magnetic flux directed toward the outer outer peripheral surface 4112 in the radial direction R is increased.

[0049] In this embodiment, the connecting portion 413 has a plurality of branched branches (hereinafter referred to as branched portions 413a and 413b). The connecting portion 413 is connected to the annular portion 412 in the radial direction R via the branched portions 413a and 413b. That is, the connecting portion 413 has branched portions 413a and 413b that are a plurality of portions branched toward the annular portion 412. The branched portions 413a and 413b are connected to the annular portion 412.

[0050] In this case, a gap 413H is formed in a portion surrounded by the branched portions 413a and 413b of the connecting portion 413 and the annular portion 412. The gap 413H is disposed outside the second protruding portion 415 in the radial direction R, and the annular portion 412 and the gap 413H are adjacent to each other in the radial direction R. That is, the gap 413H is formed between the branched portions 413a and 413b in the circumferential direction C.

[0051] Since gap 413H also functions as a flux barrier, magnetic paths M9 and M10 passing through branch portions 413a and 413b from connecting portion 413 toward annular portion 412 are also narrowed. Even in this configuration, the magnetic flux from the inner side in the radial direction R toward outer peripheral surface 4112 on the outer side is increased on side surfaces 423 and 424 of magnet 42. Note that gap 413H may be filled with air or a non-magnetic material (for example, a resin having a magnetic permeability lower than that of a magnetic material such as an electromagnetic steel sheet forming stator 3).

[0052] Based on the various configurations described above, by increasing the magnetic flux directed toward the outer peripheral surface 4112 of the magnetic pole portion 411 in the radial direction R, it is possible to increase the magnetic flux directed from the outer peripheral surface 4112 toward the teeth 32 of the stator 3 located outside the radial direction R, thereby increasing the detent torque.

[0053] In this embodiment, the second protruding portion 415 and the magnetic pole portion 411 face each other in the radial direction R via the gap 413H and the connecting portion 413. In this case, the stress applied to the second protruding portion 415 in the radial direction R due to the press-fitting of the shaft 2 is alleviated by the presence of the gap 413H. In other words, when the shaft 2 is press-fitted, deformation of the magnetic body 41 and deterioration of the roundness are suppressed.

[0054] The motor 1 of this embodiment may be required to produce high torque at high ambient temperatures, for example, at ambient temperatures of 120° C. to 150° C. In such cases, the torque may be suppressed by a demagnetizing field due to the ampere turns of the coil 33 in addition to demagnetization due to heat.

[0055] It is known that magnets with a high dysprosium (Dy) content can be used to suppress demagnetization, but increasing the proportion of dysprosium in the magnet increases manufacturing costs and reduces residual magnetic flux density (Br).

[0056] Therefore, in this embodiment, as shown in FIG. 4, the magnet 42 is disposed on the inner side in the radial direction R of the rotor 4. For example, the outer diameter D1 of the outer end face 422 of the magnet 42 is 22.6 mm. With this configuration, by ensuring a sufficient distance between the coil 33 of the stator 3, which is located on the outer side in the radial direction R, and the outer end face 422 of the magnet 42, the demagnetization rate of the magnet 42 due to heat and ampere turns can be kept low, for example, to a maximum of about 2%. This allows for high stall torque. Furthermore, a magnet with a low dysprosium content, such as one with Hcj = 1500 to 1600 KA / m, can be used for the magnet 42.

[0057] Furthermore, in a spoke-type IPM, if multiple magnetized magnets 42 are inserted into the magnetic body 41 (pre-magnetization), a reaction force is generated between the multiple magnets 42, It may be difficult to assemble the magnets 42 by inserting them into the magnetic body 41. Therefore, it is desirable to magnetize the magnets 42 after inserting them into the magnetic body 41 (attaching after magnetization).

[0058] On the other hand, magnetization may not be possible if the outer end surface 422 of the magnet 42 comes too close to the annular portion 412 in the radial direction R. Furthermore, if the length of the magnet 42 in the radial direction R becomes large, it may become difficult to apply a magnetic field to the entire magnet 42 during magnetization, so the length of the magnet 42 in the radial direction R may be shortened.

[0059] Therefore, in this embodiment, the length L1 of the magnet 42 in the radial direction R (hereinafter referred to as the magnet length) shown in FIG. 4 is shortened. For example, the magnet length L1 is set to be the outer diameter D of the rotor 4× By setting the ratio (for example, a predetermined value smaller than the outer diameter (for example, 3.5) / outer diameter D (for example, 24.5 mm)), the magnetization rate can be made 90% or more, and the entire magnet 42 can be magnetized.

[0060] Furthermore, it is known that in a motor 1 equipped with an IPM rotor, increasing the surface area of the magnet 42 that contacts the magnetic pole portion 411 increases torque. However, if the magnet 42 is extended in the radial direction R to near the annular portion 412, the magnitude of magnetic resistance from the magnet 42 to the annular portion 412 becomes relatively small. As a result, the magnitude of the magnetic flux of the magnet 42 that flows toward the annular portion 412 becomes larger than the magnetic flux that flows toward the stator 3. As a result, the surface area of the magnet 42 that contacts the magnetic pole portion 411 and the magnitude of the torque may no longer be proportional. In particular, in the case where the magnetic body 41 is formed with the first protruding portion 414 that supports the inner end face 421 of the magnet 42 from the inside in the radial direction R, extending the magnet 42 to near the annular portion 412 in the radial direction R makes it easier for the magnetic flux to flow toward the annular portion 412 via the contact portion between the magnet 42 and the first protruding portion 414.

[0061] In this embodiment, as the magnet length L1 of the magnet 42 is shortened, the magnet 42 is disposed so as to be a predetermined distance away from the annular portion 412 in the radial direction R. For example, the inner diameter D2 of the inner end face 421 of the magnet 42 is equal to or greater than ½, and preferably equal to or greater than ⅔, the outer diameter (external size) D0 of the rotor 4. In other words, the distance from the inner end face of the magnet 42 to the annular portion 412 is equal to or greater than ½, and preferably equal to or greater than ⅔, the outer diameter (external size) D0 of the rotor 4.

[0062] Furthermore, the motor 1 in the embodiment is a small-diameter motor 1, for example, with a rotor 4 having a diameter of 24.5 mm or less. When the outer diameter (size) of the rotor 4 is small, it may be difficult to manufacture the recess 4111b with a fine shape. For example, it may be difficult to make the width of the recess 4111b in the circumferential direction C 0.25 mm or less.

[0063] By forming the recess 4111b in the magnetic body 41 according to the embodiment, it is possible to ensure a predetermined contact area between the magnetic pole portion 411 and the magnet 42 without extending the magnet 42 to the annular portion 412 in the radial direction R. Furthermore, by enlarging the recess 4111b, it is possible to reduce the weight of the magnetic pole portion 411, thereby reducing the inertia of the rotor 4, which is a rotating body. In other words, the rotor 4 according to the embodiment can suppress an increase in the moment of inertia of the rotor 4. In other words, the rotor 4 according to the embodiment can suppress an increase in GD2 (G Disk Air) of the rotor 4.

[0064] Next, a case will be described in which the motor 1 according to this embodiment is used as a motor 1 for driving a vehicle. The shaft 2 of the motor 1 described above is connected to the drive system of the vehicle via, for example, a first gear 302, a second gear 303, and an output shaft 304. The drive system of the vehicle includes a differential gear, and the power of the motor 1 is transmitted to the differential gear and then distributed and transmitted from the differential gear to the drive wheels, which consist of the left and right front wheels or rear wheels. As a result, when the motor 1 is driven, the left and right drive wheels rotate, and the vehicle moves forward or backward.

[0065] In such a motor 1, when the vehicle engine and motor 1 are not driven, it is desirable that the rotor 4 be stopped relative to the stator 3 so that the drive wheels do not rotate. For example, it is desirable that the drive wheels do not rotate even when the vehicle is parked on a steep slope. In other words, it is desirable that the detent torque (cogging torque) of such a motor 1 be increased when the motor 1 is not driven. Therefore, by providing the recesses and protrusions described below, the motor 1 according to this embodiment can increase the detent torque (magnetic attraction torque acting between the magnet 42 and the magnetic pole portions 30, 411 when the coil 33 is not excited).

[0066] Therefore, the recesses and protrusions of the magnetic pole portions 411 of the rotor 4 will be described using Figure 8. Figure 8 is an enlarged view of a portion of Figure 4. In the rotor 4 according to this embodiment, an outer peripheral surface 4112 extending in the circumferential direction C has a plurality of recesses (hereinafter referred to as recesses DE1) recessed inward in the radial direction R and a plurality of protrusions (hereinafter referred to as protrusions PR1) protruding outward in the radial direction R. The outer peripheral surface 4112 extending in the circumferential direction C of the magnetic pole portions 411 is an example of a side surface extending in the circumferential direction C of the magnetic pole portions 411.

[0067] For example, three recesses DE1 (a first recess DE1a, a second recess DE1b, and a third recess DE1c) are provided in one magnetic pole portion 411. The second recess DE1b and the third recess DE1c are arranged symmetrically with respect to an imaginary center line CL1 located in the center of one magnetic pole portion 411 in the circumferential direction C.

[0068] For example, four protrusions PR1 (first protrusion PR1a, second protrusion PR1b, third protrusion PR1c, and fourth protrusion PR1d) are provided on one magnetic pole portion 411. The first protrusion PR1a and second protrusion PR1b are arranged line-symmetrically with respect to an imaginary center line CL1 located at the center of one magnetic pole portion 411 in the circumferential direction C, and the third protrusion PR1c and fourth protrusion PR1d are arranged line-symmetrically with respect to the imaginary center line CL1.

[0069] Next, the recesses and protrusions of the magnetic pole portions 411 of the stator 3 will be described with reference to FIG. 9. FIG. 9 is an enlarged view of the magnetic pole portions 30 of the stator 3 included in the motor 1 shown in FIG. 3. The magnetic pole portions 30 of the stator 3 are composed of a yoke 31 and teeth 32. In the radial direction R of the motor 1 according to this embodiment, the outer peripheral surfaces (side surfaces) 4112 of the magnetic pole portions 411 of the rotor 4 face the inner peripheral surfaces (side surfaces) 321 of the teeth 32 of the stator 3 (see FIG. 10). The inner peripheral surfaces 321 extending in the circumferential direction C of the teeth 32 are formed with a plurality of recesses (hereinafter referred to as recesses DE2) recessed outward in the radial direction R and a plurality of protrusions (hereinafter referred to as protrusions PR2) protruding inward in the radial direction R.

[0070] For example, three recesses DE2 (a first recess DE2a, a second recess DE2b, and a third recess DE2c) are provided in one magnetic pole portion 411. The second recess DE2b and the third recess DE2c are arranged symmetrically with respect to an imaginary center line CL2 located in the center of one magnetic pole portion 411 in the circumferential direction C.

[0071] For example, four protrusions PR2 (a first protrusion PR2a, a second protrusion PR2b, a third protrusion PR2c, and a fourth protrusion PR2d) are provided on one magnetic pole portion 411. The first protrusion PR2a and the second protrusion PR2b are arranged line-symmetrically with respect to an imaginary center line 2CL located at the center of one magnetic pole portion 411 in the circumferential direction C, and the third protrusion PR2c and the fourth protrusion PR2d are arranged line-symmetrically with respect to the imaginary center line 2CL.

[0072] Next, the relationship between the recessed portion DE1 and the protruding portion PR1 of the magnetic pole portion 411 of the rotor 4 and the recessed portion DE2 and the protruding portion PR2 of the magnetic pole portion 30 of the stator 3 will be described with reference to Figures 10 and 11. Figure 10 is a plan view of the recessed portion DE1 and the protruding portion PR1 of the magnetic pole portion 411 of the rotor 4, and the recessed portion DE2 and the protruding portion PR2 of the magnetic pole portion 30 of the stator 3. Figure 11 is an enlarged view of the recessed portion DE1 and the protruding portion PR1 of the magnetic pole portion 411 of the rotor 4, and the recessed portion DE2 and the protruding portion PR2 of the magnetic pole portion 30 of the stator 3.

[0073] As described above, three recesses DE1 and four protrusions PR1 are formed in one magnetic pole portion 411 of the rotor 4. On the other hand, three recesses DE2 and four protrusions PR1 are formed in one magnetic pole portion 30 of the stator 3. In other words, the number of recesses DE1 or protrusions PR1 in one magnetic pole portion 411 of the rotor 4 is the same as the number of recesses DE2 or protrusions PR2 in one magnetic pole portion 30 of the stator 3.

[0074] Furthermore, in the radial direction R when the vehicle engine and motor 1 are not driving, the recess DE1 of the rotor 4 faces the recess DE2 of the stator 3, and the protrusion PR1 of the rotor 4 faces the protrusion PR2 of the stator 3.

[0075] For example, as shown in Figure 11, in the radial direction R, the first recess DE1a of the rotor 4 faces the first recess DE2a of the stator 3, the second recess DE1b of the rotor 4 faces the second recess DE2b of the stator 3, and the third recess DE1c of the rotor 4 faces the third recess DE2c of the stator 3.

[0076] Furthermore, in the radial direction R, the first protrusion PR1a of the rotor 4 faces the first protrusion PR2a of the stator 3, the second protrusion PR1b of the rotor 4 faces the second protrusion PR2b of the stator 3, the third protrusion PR1c of the rotor 4 faces the third protrusion PR2c of the stator 3, and the fourth protrusion PR1d of the rotor 4 faces the fourth protrusion PR2d of the stator 3.

[0077] Also, as shown in Figure 10, when four protrusions PR1 in one magnetic pole portion 411 of the rotor 4 face four protrusions PR2 in one magnetic pole portion 30 of the stator 3 in the radial direction R, in the magnetic pole portion 411 adjacent to the magnetic pole portion 411 in the circumferential direction C, three protrusions PR1 of the rotor 4 face three protrusions PR2 of the stator 3 in the radial direction R.

[0078] Furthermore, in the motor 1 according to this embodiment, when the four protruding portions PR1 of one magnetic pole portion 411 of the rotor 4 face the four protruding portions PR2 of one magnetic pole portion 411 of the stator 3 in the radial direction R, at least two protruding portions PR1 of the rotor 4 face two protruding portions PR2 of the stator 3 in the radial direction R between the remaining one magnetic pole portion 411 of the rotor 4 and one magnetic pole portion 30 of the stator 3. As shown in Figure 11, the convex portion PR1 of the rotor 4 and the convex portion PR2 of the stator 3, which are opposed to each other in the radial direction R, form a magnetic circuit MC (see Figure 11) that passes through the convex portion PR1 of the magnetic pole portion 411 of the rotor 4 and the convex portion PR2 of the magnetic pole portion 30 of the stator 3, and also passes through the magnetic pole portion 411 of the rotor 4 having the convex portion PR1 and the magnetic pole portion 30 of the stator 3 having the convex portion PR2, based on the magnetic force of the magnet 42 of the rotor 4.

[0079] For these reasons, when the vehicle engine and motor 1 are not driven, a magnetic circuit MC is formed between the magnetic pole portion 411 of the rotor 4 and the magnetic pole portion 30 of the stator 3 by the magnet 42 of the rotor 4, passing through the protrusion PR1 of the rotor 4 and the protrusion PR2 of the stator 3, and a detent torque (cogging torque) is generated that prevents the rotor 4 from rotating in the circumferential direction C relative to the stator 3.

[0080] Furthermore, in the motor 1 according to this embodiment, the detent torque is increased by providing a plurality of protrusions PR1 on the outer peripheral surface 4112 of the magnetic pole portion 411 of the rotor 4 and a plurality of protrusions PR2 on the inner peripheral surface 321 of the magnetic pole portion 30 of the stator 3. Therefore, there is no need to provide a rotor of a braking device separate from the rotor 4 of the driving motor 1 on the shaft 2, which prevents the electronic device 300 from becoming larger and also prevents an increase in the number of magnets used.

[0081] In the motor 1 according to this embodiment, the number MA of magnets 42 in the rotor 4 is 10, and the number SL of slots (spaces that house coils 33) in the stator 3 is 12 (12 slots). Therefore, in the motor 1 according to this embodiment, the cogging torque (detent torque) increases at 60 positions, which is the least common multiple of 10 and 12 slots, out of 360 degrees in the circumferential direction C, resulting in the generation of so-called cogging ripples (waves). In the cogging ripples, 360 degrees divided by 60 is 6 (degrees / 1), which is the period of one wave.

[0082] In other words, if the number of magnets 42 in the rotor 4 is MA, the number of slots (coils 33) in the stator 3 is SL, and the least common multiple of MA and SL is X, then 360 (degrees) divided by X is Y (degrees / 1), which is the period of the cogging ripple. According to findings based on extensive research conducted by the present inventors, the cogging torque can be increased by arranging the protrusions PR1 and recesses DE1 in accordance with the period (one wave) of the cogging ripple. For example, in the motor 1 according to this embodiment, the cogging torque can be increased by arranging two protrusions PR1 and two recesses DE1 in accordance with the period (one wave) of the cogging ripple. In other words, in the motor 1 according to this embodiment, when the least common multiple of the numbers MA and SL is X, at least one recessed portion DE1, DE2 and one protruding portion PR1, PR2 are arranged on the outer peripheral surface (side surface) 4112 of the rotor 4 and the inner peripheral surface (side surface) 321 of the teeth 32, respectively, so as to correspond to the period of the cogging ripple for every angle obtained by dividing 360 degrees by X.

[0083] In the motor 1 according to this embodiment, the outer diameter of the rotor 4 is φ24.5 mm, so the circumferential length of the rotor 4 is 24.5 mm × π = 76.93 mm. Since the least common multiple X of MA and SL is 60, the period (one wave) of the cogging ripple, that is, the period between the recessed portion DE1 and the protruding portion PR1, is 76.93 mm ÷ 60 = 1.28 mm.

[0084] In the motor 1 according to this embodiment, the cogging torque can be increased by alternately arranging the recessed portions DE1 and the protruding portions PR1 as follows in accordance with the period of the cogging ripple. That is, by arranging, for example, two recessed portions DE1 and two protruding portions PR1 alternately on the outer peripheral surface 4112 of the magnetic pole portion 411 of the rotor 4, approximately 1.28 mm from the outer peripheral surface of the rotor 4, the recessed portions DE1 and the protruding portions PR1 can be arranged to match the shape of the cogging ripple. By arranging the recessed portions DE1 and the protruding portions PR1 in this way, the recessed portions DE1 and the protruding portions PR1 are arranged every 1.5 degrees.

[0085] In addition, it is preferable to alternately arrange the recesses DE and the protrusions PR1 on the inner circumferential surface 321 of the teeth 32 of the stator 3 in accordance with the number of recesses DE1 and the number of protrusions PR1 on the rotor 4 in order to improve the cogging torque.

[0086] The length of one magnet 42 in the circumferential direction C is 2.29 mm. Therefore, adding up the lengths of one magnet 42 in the circumferential direction C is 2.29 mm × 10 = 22.9 mm. And, because 22.9 mm is the length in the circumferential direction C occupied by the magnet 42, the length (outer circumference) in the circumferential direction C of the magnetic body 41, which is an electromagnetic steel plate, is 76.93 mm - 22.9 = 56.48 mm.

[0087] The number of pairs of concave and convex portions forming the period of the cogging ripple is 53.48 mm ÷ 1.28 mm ≈ 42, and there should be about 40 pairs of convex and concave portions for 12 poles for the 10 magnetic poles of the magnet 42 .

[0088] To summarize the above, the cogging torque can be improved by matching the waveform of the cogging ripple formed by the slot combination (a combination of a rotor 4 having ten magnets 42 and a stator 3 having space for accommodating twelve coils 33) with the shape of the inner circumferential surfaces (side surfaces) 321 of the teeth 32, which are the magnetic pole portions 30 of the stator 3. Furthermore, the cogging torque can be improved by matching the waveform of the cogging ripple formed by the slot combination with the shape of the outer circumferential surfaces (side surfaces) 4112 of the magnetic pole portions 411 of the rotor 4.

[0089] 8, the magnetic pole portion 411 of the rotor 4 according to this embodiment includes, on the outer side in the radial direction R, two corner portions 4CO and a portion (outer peripheral surface 4112) extending in the circumferential direction C between the two corner portions 4CO. Therefore, more magnetic flux is directed in the circumferential direction C between the corner portions 4CO of the magnetic pole portion 411 of the rotor 4 and the teeth 32 which are the magnetic pole portions 30 of the stator 3, thereby increasing the contribution to torque. Therefore, a magnetic accompanying force in the circumferential direction C is generated between the corner portions 4CO of the magnetic pole portion 411 of the rotor 4 and the teeth 32 which are the magnetic pole portions 30 of the stator 3.

[0090] On the other hand, the magnetic flux is directed in the radial direction R between the portion (outer peripheral surface 4112) of the magnetic pole portion 411 of the rotor 4 extending in the circumferential direction C and the teeth 32 which are the magnetic pole portions 30 of the stator 3, so the contribution to torque is small. Therefore, no accompanying magnetic force in the circumferential direction C is generated between the portion (outer peripheral surface 4112) of the magnetic pole portion 411 of the rotor 4 extending in the circumferential direction C and the teeth 32 which are the magnetic pole portions 30 of the stator 3. Even if a magnetic accompanying force is generated, it is smaller than the accompanying magnetic force in the circumferential direction C generated between the corner portion 4CO of the magnetic pole portion 411 of the rotor 4 and the teeth 32 which are the magnetic pole portions 30 of the stator 3.

[0091] Next, the presence or absence of recesses DE1, DE2 and protrusions PR1, PR2 will be described with reference to FIGS. 12 to 15. FIG. 12 is a diagram showing the flow of magnetic flux of the magnet 42 of the rotor 4 relative to the stator 3 and the magnitude of magnetic flux density when the magnetic body 41 of the rotor 4 and the teeth 32 of the stator 3 face each other. FIG. 13 is a diagram showing the waveform of cogging torque in the state shown in FIG. 12. FIG. 14 is a diagram showing the flow of magnetic flux of the magnet 42 of the rotor 4 relative to the stator 3 and the magnitude of magnetic flux density when the rotor 4 is rotated slightly in the circumferential direction C from the state in which the magnetic body 41 of the rotor 4 and the teeth 32 of the stator 3 face each other and no longer face each other. FIG. 15 is a diagram showing the waveform of cogging torque in the state shown in FIG. 14.

[0092] As can be seen from Figure 13, when the magnetic pole portion 411 of the rotor 4 and the teeth 32, which are the magnetic pole portion 30 of the stator 3, and the magnetic pole portion 411 of the rotor 4 do not have the recesses DE1 and DE2 and do not have the protrusions PR1 and PR2, the magnetic flux is mainly directed in the radial direction R, and the component of the magnetic flux that contributes to the torque in the circumferential direction C is small.

[0093] On the other hand, as can be seen from Figures 13 to 15, when the magnetic pole portion 411 of the rotor 4 and the teeth 32 which are the magnetic pole portion 30 of the stator 3 and the magnetic pole portion 411 of the rotor 4 have recesses DE1 and DE2 and protrusions PR1 and PR2, the magnetic flux is mainly directed in the circumferential direction C, and the component of the magnetic flux that contributes to the torque becomes large.

[0094] As described above, the rotor 4 in this embodiment comprises a magnetic body 41 having two magnetic pole portions 411, an annular portion 412, and two connecting portions 413 connecting the two magnetic pole portions 411 and the annular portion 412, and a magnet 42 located between the two magnetic pole portions 411 in the circumferential direction C, and one or more recesses (concave) DE1 or one or more protrusions (protrusions) PR1 are formed on the outer peripheral surface (side surface) 4112 extending in the circumferential direction C of the two magnetic pole portions 411.

[0095] In the rotor 4 according to this embodiment, the magnetic body 41 has a first protrusion (protrusion) 414 that protrudes from the annular portion 412, and the magnet 42 is in contact with the first protrusion (protrusion) 414 in the radial direction R.

[0096] In the rotor 4 according to this embodiment, the first protrusion (protrusion) 414 has a plurality of branch portions (portions) 413a, 413b branching out toward the annular portion 412, and the branched branch portions (portions) 413a, 413b are connected to the annular portion 412, and a gap 413H is formed between the branched branch portions (portions) 413a, 413b in the circumferential direction C.

[0097] The motor 1 of this embodiment comprises a rotor 4 and a stator 3, and the stator 3 comprises a plurality of magnetic pole portions 30, and in the radial direction R, one or more recesses (concave) DE20 or one or more protrusions (protrusions) PR20 are formed on the inner surface (side) 321 of the magnetic pole portion 30 facing the outer surface (side) 4112 of the rotor 4.

[0098] In the motor 1 according to this embodiment, the number of recesses (concave) DE1 or protrusions (convex) PR1 on the rotor 4 is the same as the number of recesses (concave) DE2 or protrusions (convex) PR2 on the stator 3.

[0099] In the motor 1 according to this embodiment, when the number MA of magnets 42 of the rotor 4 is different from the number SL of slots (teeth) of the stator 3, and the least common multiple of the number MA of magnets 42 of the rotor 4 and the number SL of slots (teeth) of the stator 3 is X, at least one recess DE1, DE2 and one protrusion PR1, PR2 are arranged on the outer peripheral surface (side surface) 4112 of the rotor 4 and the inner peripheral surface (side surface) 321 of the teeth 32, respectively, for every angle obtained by dividing 360 degrees by X.

[0100] The electronic device 300 according to this embodiment includes a motor 1 and a housing 301 that houses the motor 1.

[0101] The electronic device 300 according to this embodiment includes a motor 1 and one or more gears 302 and 303.

[0102] In the above-described rotor 4 and stator 3, three recesses DE1, DE2 and four protrusions PR1, PR2 are formed on one magnetic pole portion 411. However, the numbers of recesses DE1, DE2 and protrusions PR1, PR2 formed on the rotor 4 and stator 3 according to the present invention can be increased or decreased to an appropriate number as needed.

[0103] Furthermore, in the rotor 4 described above, the first screw N1 is inserted into the first through-hole 411H and the first screw N2 is inserted into the second through-hole 412H, thereby engaging the multiple magnetic members 410. However, the rotor 4 according to the present invention is not limited to this, and for example, the multiple magnetic members 410 may be engaged by inserting the screws N1, N2 into only one of the two through-holes 411H, 412H. Of course, the engagement of the multiple magnetic members 410 is not limited to using the screws N1, N2, and may be achieved by other methods.

[0104] Furthermore, in the rotor 4 described above, the number of magnetic pole portions 411 and the number of connecting portions 413 provided on the magnetic body 41 are not limited to ten, but may be a plural number of nine or less, or a plural number of eleven or more.

[0105] Furthermore, in the above-described motor 1, the number of recesses DE1 or protrusions PR1 of one magnetic pole portion 411 of the rotor 4 is the same as the number of recesses DE2 or protrusions PR2 of one magnetic pole portion 30 of the stator 3. However, the motor 1 according to the present invention is not limited to this, and the number of recesses DE1 or protrusions PR1 of one magnetic pole portion 411 of the rotor 4 may be different from the number of recesses DE2 or protrusions PR2 of one magnetic pole portion 30 of the stator 3.

[0106] Furthermore, the above-described motor 1 has been described as having recesses DE1 and protrusions PR1 provided on magnetic pole portion 411 of rotor 4, and recesses DE2 and protrusions PR2 provided on magnetic pole portion 30 of stator 3. However, motor 1 according to the present invention is not limited to this, and recesses DE1, DE2 and protrusions PR1, PR2 may be provided on only one of magnetic pole portion 411 of rotor 4 and magnetic pole portion 30 of stator 3.

[0107] In the above-described motor 1, a plurality of recesses DE1 and a plurality of protrusions PR1 are arranged on one magnetic pole portion 411 of the rotor 4, with respect to the imaginary center line CL1. However, the recesses DE1 and protrusions PR1 according to the present invention are not limited to this. For example, the recesses DE1 and protrusions PR1 may be arranged at equal intervals along the circumferential direction C.

[0108] Furthermore, in the above-described motor 1, a plurality of recesses DE2 and a plurality of protrusions PR2 are arranged on one magnetic pole portion 30 of the stator 3, with respect to the imaginary center line CL2. However, the recesses DE2 and protrusions PR2 according to the present invention are not limited to this. For example, the recesses DE2 and protrusions PR2 may be arranged at equal intervals along the circumferential direction C.

[0109] While the present invention has been described above based on the embodiments, it goes without saying that the present invention is not limited to the embodiments and that various modifications can be made without departing from the spirit of the present invention. Such modifications made without departing from the spirit of the present invention are also included in the technical scope of the present invention, and this will be clear to those skilled in the art from the description of the claims. [Explanation of symbols]

[0110] 1 motor, 3 stator, 30 magnetic pole portion, 321 inner peripheral surface (side surface), 4 rotor, 41 magnetic body, 411 magnetic pole portion, 4112 outer peripheral surface (side surface), 412 annular portion, 413 connection portion, 413a, 413b branch portion (branched portion), 413H air gap, 414 first protrusion (protrusion), 42 magnet, 300 electronic device, 301 housing, 302, 303 gear, A axial direction, C circumferential direction, DE1 recess, DE2 recess, PR1 protrusion, PR2 protrusion

Claims

1. a magnetic body having two magnetic pole portions, an annular portion, and two connection portions connecting the two magnetic pole portions and the annular portion; a magnet located between the two magnetic pole portions in the circumferential direction; Equipped with A rotor in which one or more recesses or one or more protrusions are formed on the circumferentially extending side surfaces of the two magnetic pole portions.

2. the magnetic body includes a protrusion protruding from the annular portion, The rotor according to claim 1 , wherein the magnets are in contact with the protrusions in the radial direction.

3. the protrusion has a plurality of portions branching toward the annular portion, the branched portions are connected to the annular portion; The rotor according to claim 2 , wherein gaps are formed between the branched portions in the circumferential direction.

4. A rotor according to any one of claims 1 to 3; a stator; Equipped with the stator includes a plurality of magnetic pole portions, A motor in which one or more recesses or one or more protrusions are formed on the side surface of the magnetic pole portion that faces the side surface of the rotor in the radial direction.

5. The motor according to claim 4 , wherein the number of the plurality of recesses or protrusions of the rotor is the same as the number of the plurality of recesses or protrusions of the stator.

6. When the number of the magnets of the rotor is different from the number of slots of the stator, and the least common multiple of the number of the magnets of the rotor and the number of slots of the stator is X, The motor according to claim 5 , wherein at least the recesses and the protrusions are arranged on the side surfaces of the rotor and the teeth, respectively, at intervals of an angle obtained by dividing 360 degrees by X.

7. An electronic device comprising: the motor according to claim 4; and a housing that houses the motor.

8. An electronic device comprising the motor according to claim 6 and one or more gears.

Images