Motor and electronic apparatus

Abstract

To increase a detent torque.SOLUTION: A motor includes: a first rotor with a plurality of magnets lining in an axial direction; and a second rotor with a plurality of magnets. The second rotor has a larger detent torque than the first rotor and the first and second rotors have the same number of magnets.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Among inner rotor type motors, there is one in which the rotor is provided with a plurality of magnets and a magnetic body formed by laminating thin metal plates, and the magnetic body is formed in 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 motors have room for improvement in terms of increasing the detent torque.

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

[0006] In one aspect, the motor comprises a first rotor having a plurality of magnets arranged axially, and a second rotor having a plurality of magnets, the second rotor having a larger detent torque than the first rotor, and the number of magnets of the first rotor is the same as the number of magnets of the second rotor.

[0007] In 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 a first embodiment. [Figure 2] 2 is an exploded perspective view of a drive device 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] 8 is an exploded perspective view of a braking device included in the electronic device shown in FIG. [Figure 9] FIG. 9 is a perspective view of the magnetic body and magnet of the rotor provided in the braking device shown in FIG. [Figure 10] FIG. 10 is a front view of the magnetic body and the magnet shown in FIG. [Figure 11] FIG. 11 is an enlarged view of a portion of FIG. [Figure 12] FIG. 12 is a front view showing the magnetic circuits formed in the stator and rotor. [Figure 13] FIG. 13 is a cross-sectional view of the stator and rotor shown in FIG. [Figure 14] FIG. 14 is a front view of a modified stator. [Figure 15] FIG. 15 is an enlarged view of a portion of FIG. [Figure 16-1] FIG. 16-1 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 (magnetic pole portion) of the rotor faces the teeth of the stator. [Figure 16-2] FIG. 16-2 is a diagram showing the waveform of the cogging torque. [Figure 16-3]Figure 16-3 is a diagram showing the flow of magnetic flux from the rotor magnet relative to the stator and the magnitude of the magnetic flux density when the rotor rotates from an opposing state between the rotor's magnetic body (magnetic pole portion) and the stator's teeth to a non-opposing state. [Figure 17] FIG. 17 is a perspective view of an electronic device according to the second embodiment. [Figure 18] 18 is an exploded perspective view of the braking device included in the electronic device shown in FIG. [Figure 19] 19 is a perspective view of the magnetic body and magnet of the rotor provided in the braking device shown in FIG. [Figure 20] FIG. 20 is a front view of the magnetic body and the magnet shown in FIG. [Figure 21] FIG. 21 is an enlarged view of a portion of FIG. [Figure 22] FIG. 22 is a cross-sectional view of the rotor shown in FIG. [Figure 23] FIG. 23 is a perspective view of a magnetic body included in the rotor shown in FIG. [Figure 24] FIG. 24 is an enlarged view of a portion of FIG. [Figure 25] FIG. 25 is an enlarged view of a magnetic pole portion of a stator included in the motor shown in FIG. [Figure 26] FIG. 26 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 27] FIG. 27 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 28] FIG. 28 is a schematic diagram showing the magnetization of the rotor magnet of the driving device and the magnetization of the rotor magnet of the braking device. DETAILED DESCRIPTION OF THE INVENTION

[0009] [First embodiment] The motor 1 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 reality. 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 rotors 4, 7 rotate 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, the motor 1 will be described using Figure 1. In this embodiment, the motor 1 includes a shaft 2, a driving device 10 that rotates the shaft 2 in a circumferential direction C, and a braking device 50 that maintains the state in which the rotation of the shaft 2 in the circumferential direction C has stopped.

[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 driving device 10 shown in Fig. 2 includes a stator 3 and a rotor 4. Fig. 2 is an exploded perspective view of the driving device 10 included in the electronic device 300 shown in Fig. 1. Note that the motor 1 according to this embodiment is, for example, an inner rotor type brushless motor in which the stator 3 is located outside the rotor 4 in the radial direction R.

[0016] 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 parts, 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.

[0017] The yoke 31 is formed in an annular shape and located outside the stator 3 in the radial direction R. The teeth 32 protrude from the inner peripheral surface of the yoke 31 toward the inside in the radial direction R. In this embodiment, 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.

[0018] The coils 33 are wound around the teeth 32, for example, via insulators 34. The coils 33 are electrically connected to a DC power supply. When the motor 1 is driven, a DC voltage is applied to the coils 33 from the DC power supply, which generates a magnetic field in the coils 33 that changes over time. The interaction between this magnetic field and the magnetic force of the magnets 42 causes the rotor 4 to rotate in the circumferential direction C relative to the stator 3.

[0019] 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 disposed such that, for example, the same magnetic poles of two adjacent magnets 42 in the circumferential direction C face the magnetic pole portion 411, and the two magnets 42 are oriented to repel each other. The rotor 4 is a so-called IPM (Interior Permanent Magnet) rotor that includes the plurality of magnets 42 and the magnetic body 41 that houses the plurality of magnets 42, and the plurality of magnets 42 are disposed radially. The outer size (outer diameter D0) of the rotor 4 according to this embodiment is, for example, 24.5 mm (see FIG. 4).

[0020] 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.

[0021] 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 shown in FIG. 4 in the circumferential direction C is, for example, an outer diameter of 2.29 mm, and the length (length in the radial direction R) L1 (see FIG. 5) of the magnet 42 is, for example, 3.50 mm.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 2 and 6, the inner circumferential portion 433 protrudes from the inner peripheral 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.

[0030] 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.

[0031] Furthermore, the main body 431 of one cover 43a faces (or contacts) one surface of the magnet 42 in the axial direction A, and the main body 431 of the other cover 43b faces (or contacts) the other surface of the magnet 42 in the axial direction A. With this configuration, movement of the magnet 42 in the axial direction A is suppressed.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] The magnetic pole portions 411 are disposed on the outer side in the radial direction R of the magnetic body 41, and are formed in a generally 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 generally fan-like shape that gradually widens outward in the radial direction R so that the width in the circumferential direction C of the outer peripheral surface 4112 away from the axis 2o is larger than the width in the circumferential direction C of the inner peripheral surface 4111 close to the axis 2o. The magnetic pole portions 411 form the outer peripheral 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, for example, arranged in a line in the circumferential direction C at predetermined intervals (for example, equal intervals).

[0036] 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.

[0037] 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.

[0038] The outer peripheral surface 4112 is formed in an arc shape when viewed from the axial direction A, and is a curved surface extending along the circumferential direction C. The outer peripheral surface 4112 is an example of a side surface extending in the circumferential direction of the magnetic pole portion 411. End portions formed by curved surfaces are arranged between the outer peripheral surface 4112 and the side surfaces 4113 and 4114, respectively.

[0039] 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.

[0040] 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.

[0041] 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).

[0042] 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.

[0043] Also, as shown in Figure 5, the magnetic pole portion 411 has a first through hole 411H as a hole portion that penetrates the magnetic pole portion 411 in the axial direction A, and the annular portion 412 has a second through hole 412H as a hole portion that penetrates the annular portion 412 in the axial direction A.

[0044] 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.

[0045] The magnetic members 410 are coupled to one another by first screws N1 inserted through the first through holes 411H, respectively, and by second screws N2 inserted through the second through holes 412H, respectively. 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. That is, the first screws N1 and the second screws N2 function as flux barriers. Note that in this embodiment, the first screws N1 and the second screws N2, and the first through holes 411H and the second through holes 412H serving as fastening members may be replaced with first convex portions, second convex portions, first concave portions, and second concave portions, and the first convex portions may be fitted into the first concave portions and the second convex portions may be fitted into the second concave portions to fit the magnetic members together (caulking).

[0046] 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.

[0047] 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.

[0048] 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.

[0049] Furthermore, recesses 4111b are formed in the inner circumferential surface 4111 of the magnetic pole portion 411, and the magnetic permeability of the recesses 4111b is lower than that of the magnetic body 41, so the recesses 4111b function as flux barriers. 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 it easier for magnetic saturation 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 magnetic permeability lower than that of a magnetic material such as an electromagnetic steel sheet forming the stator).

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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 the stator).

[0054] 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, and when the motor 1 is driven, it is possible to increase the force by which the rotor 4 rotates the shaft 2.

[0055] 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.

[0056] 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.

[0057] 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).

[0058] Therefore, in this embodiment, as shown in FIG. 4, the magnet 42 is disposed on the inside 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 22.86 mm. With this configuration, by ensuring a distance between the coil 33 of the stator 3, which is located on the outside 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 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.

[0059] Furthermore, in a spoke-type IPM, if multiple magnetized magnets 42 are inserted into the magnetic body 41 (so-called pre-magnetization), a reaction force is generated between the multiple magnets, which may make assembly difficult, such as inserting the multiple magnets 42 into the magnetic body 41. Therefore, it is desirable to magnetize the multiple magnets 42 after inserting them into the magnetic body 41 (post-magnetization mounting).

[0060] 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.

[0061] 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, by setting the magnet length L1 to the outer diameter D of the rotor 4 × 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 magnet 42 can be magnetized entirely.

[0062] 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.

[0063] 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 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.

[0064] 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.

[0065] 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.

[0066] Next, the braking device 50 will be described with reference to Fig. 8. Fig. 8 is an exploded perspective view of the braking device 50 provided in the electronic device 300 shown in Fig. 1. The braking device 50 in this embodiment includes a shaft 2, a stator 6, and a rotor 7. Note that in the braking device 50 according to this embodiment, for example, the stator 6 is located outside the rotor 7 in the radial direction R.

[0067] The stator 6 includes a yoke 61 as an annular portion and teeth 62 as magnetic pole portions 60. In this embodiment, the stator 6 is made up of electrically non-connected members. The yoke 61 and the teeth 62 are made of a magnetic material. The yoke 61 and the teeth 62 form the magnetic pole portions 60 of the stator 6.

[0068] The yoke 61 is formed in an annular shape and is located outside the stator 6 in the radial direction R. The teeth 62 protrude inward in the radial direction R from the inner peripheral surface of the yoke 61. In this embodiment, no coils are provided on the teeth 62. The multiple teeth 62 are arranged at equal intervals in the circumferential direction C, for example. The yoke 61 and the teeth 62 are formed by punching out a flat plate-shaped member made of a magnetic material (magnetic substance) such as an electromagnetic steel plate, and stacking the multiple members in the axial direction A.

[0069] Next, the rotor 7 will be described. The rotor 7 is rotatably inserted into the inside of the stator 6 in the radial direction R. The rotor 7 has a magnetic body 71, a magnet 72, and a pair of covers 73.

[0070] The rotor 7 according to this embodiment is a so-called IPM (Interior Permanent Magnet) rotor that is made up of a plurality of magnets 72 and a magnetic body 71 that houses the plurality of magnets 72, and the plurality of magnets 72 are arranged radially. The outer size (outer diameter) of the rotor 7 according to this embodiment is, for example, 24.5 mm.

[0071] The magnetic body 71 provided in the rotor 7 will be described in detail later, and next, the magnet 72 will be described using Figures 9, 10, 11, and 12. Figure 9 is a perspective view of the magnetic body 71 and magnet 72 of the rotor 7 provided in the braking device 50 shown in Figure 8. Figure 10 is a front view of the magnetic body 71 and magnet 72 shown in Figure 9. Figure 11 is an enlarged view of a portion of Figure 10. Figure 12 is a front view showing the magnetic circuit MC2 formed in the stator 6 and the rotor 7.

[0072] The multiple magnets 72 are arranged at equal intervals in the circumferential direction C, for example. The magnets 72 in this embodiment are permanent magnets extending in the axial direction A, for example. The magnets 72 are sintered magnets, for example. The magnets 72 are located between the two connecting portions 713 in the circumferential direction C. More specifically, the magnets 72 are located between the two connecting portions 713 in the circumferential direction C, with two gaps 71H interposed therebetween. The magnets 72 are formed in a substantially rectangular shape when viewed from the axial direction A.

[0073] The magnet 72 has an inner end face (inner face) 721 in the radial direction R, an outer end face (outer face) 722 in the radial direction R, and side faces 723, 724 in the circumferential direction C. In the embodiment, the width W11 (see FIG. 10) of the magnet 72 shown in FIG. 10 in the circumferential direction C is, for example, 3.5 mm, and the magnet length (length in the radial direction R) L11 (see FIG. 10) of the magnet 72 is, for example, 2.29 mm.

[0074] 12 , for example, one magnet 72 of the multiple magnets 72 in the rotor 7 according to this embodiment has its south pole arranged on the inside in the radial direction R and its north pole arranged on the outside in the radial direction R. Another magnet 72 adjacent to that magnet 72 in the circumferential direction C has its south pole arranged on the outside in the radial direction R and its north pole arranged on the inside in the radial direction R. In other words, the multiple magnets 72 are arranged such that one magnetic pole and the other magnetic pole alternate on the inside in the circumferential direction C, and are arranged such that one magnetic pole and the other magnetic pole alternate on the outside in the circumferential direction C.

[0075] Next, the pair of covers 73 will be described with reference to Figures 8 and 13. Figure 13 is a cross-sectional view of the stator 6 and rotor 7 shown in Figure 9. The cover 73 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 71. Alternatively, the cover 73 may be made by bending a material with lower magnetic permeability than the electromagnetic steel sheet that makes up the magnetic body 71, such as austenitic stainless steel.

[0076] One cover 73a of the pair of covers 73 is attached to the magnetic body 71 from one side in the axial direction A, and the other cover 73b of the pair of covers 73 is attached to the magnetic body 71 from the other side in the axial direction A. In other words, the pair of covers 73 sandwich the magnetic body 71 in the axial direction A.

[0077] The configuration of one cover 73a and the configuration of the other cover 73b are the same in the pair of covers 73. Therefore, in the following, the configuration of one cover 73a will be described, and the configuration of the other cover 73b will be assigned the same reference numerals as the one cover 73a, and description thereof will be omitted.

[0078] One cover 73a includes a main body portion 731 formed in a flat ring shape, and an inner peripheral portion 732 that protrudes in the axial direction A from the main body portion 731 at the inner peripheral edge in the radial direction R.

[0079] 8 and 13, the inner circumferential portion 732 protrudes from the inner peripheral edge of the main body portion 731 toward the inner circumferential portion 732 of the other cover 73b in the axial direction A. The inner circumferential portion 732 is formed, for example, in a cylindrical shape. Moreover, the inner circumferential portion 732 faces the inner circumferential surface of the inner ring 712 of the magnetic body 71 and is disposed so as to be in contact with the inner ring 712.

[0080] The main body 731 of one cover 73a faces (or contacts) one surface of the magnet 72 in the axial direction A, and the main body 731 of the other cover 73b faces (or contacts) the other surface of the magnet 72 in the axial direction A. With this configuration, movement of the magnet 72 in the axial direction A is suppressed.

[0081] Next, the magnetic body 71 included in the rotor 7 will be described with reference to Figures 10 and 11. As shown in Figure 10, the magnetic body 71 has an outer ring 711, an inner ring 712, and a plurality of connecting portions 713 that connect the outer ring 711 and the inner ring 712. In the rotor 7 according to the embodiment, the magnetic body 71 forms a magnetic pole portion.

[0082] The outer ring 711 is formed in an annular shape when viewed from the axial direction A. The outer ring 711 is disposed outside the inner ring 712 in the radial direction R. The outer ring 711 is also disposed outside the magnet 72 in the radial direction R, and is in contact with the outer end face 722 of the magnet 72. Therefore, when the rotor 7 rotates, the magnet 72 can be prevented from moving outward in the radial direction R.

[0083] The inner ring 712 is formed in an annular shape when viewed from the axial direction A. The inner ring 712 is disposed inside the outer ring 711 in the radial direction R. The inner ring 712 is also disposed inside the magnet 72 in the radial direction R, and is in contact with the inner end face 721 of the magnet 72. This prevents the magnet 72 from moving inward in the radial direction R. The inner ring 712 includes an annular portion 712a and a plurality of protrusions 712b that protrude from the annular portion 712a toward the outer ring 711 in the radial direction R.

[0084] The shaft 2 is disposed inside the annular portion 712a in the radial direction R (see FIG. 8). Each of the protrusions 712b is connected to a magnet 72. The multiple protrusions 712b are disposed at predetermined intervals (e.g., equal intervals), for example, in the circumferential direction C. The inner ring 712 in this embodiment includes, for example, 12 protrusions 712b.

[0085] The protrusion 712b engages the magnet 72 with the inner ring 712, and has a pair of convex portions 712b1 and 712b2 spaced apart in the circumferential direction C, and a concave portion 712b3 located between the pair of convex portions 712b1 and 712b2 in the circumferential direction C. In the present embodiment, the bottom of the concave portion 712b3 is an example of an end portion of the protrusion 712b located on the outer side in the radial direction R.

[0086] The connecting portions 713 connect the outer ring 711 and the inner ring 712. The multiple connecting portions 713 are arranged at equal intervals, for example, in the circumferential direction C. The magnetic body 71 in this embodiment includes, for example, 12 connecting portions 713.

[0087] 11, the connecting portion 713 has an end portion (portion 713a) located on the inside in the radial direction R and an end portion (portion 713b) located on the outside in the radial direction R. The connecting portion 713 is connected to the inner ring 712 by the end portion (portion 713a), and is connected to the outer ring 711 by the end portion (portion 713b).

[0088] Furthermore, the magnetic body 71 has, in the circumferential direction C, two gaps 71H between the magnet 72 and two of the multiple connecting portions 713 on both sides of the magnet 72.

[0089] Each of the gaps 71H has a first gap 71H1 located on the outer side in the radial direction R and a second gap 71H2 located on the inner side in the radial direction R. In the circumferential direction C, the first gap 71H1 is located between the magnet 72 and the connecting portion 713. In addition, in the circumferential direction C, the second gap 71H2 is located between the protruding portion 712b and the connecting portion 713. In the circumferential direction C of the braking device 50 according to this embodiment, the width W13 of the first gap is larger than the width of the second gap 41H and smaller than the width W12 of the tooth 62 (see FIG. 8) and the width of the protruding portion 712b.

[0090] A portion 713a of the connecting portion 713 that connects to the inner ring 712 is located on the inner ring 712 side relative to the end of the outer ring 711 of the protruding portion 712b (the bottom of the recessed portion 712b3).

[0091] Next, a case where the braking device 50 according to this embodiment is used in a vehicle motor 1 will be described. The rotor 4 of the drive unit 10 is fixed to the shaft 2 described above, and the shaft 2 is connected to the vehicle's drive system via, for example, a first gear 302, a second gear 303, and an output shaft 304. The vehicle's drive system includes a differential gear, and the power of the drive motor 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 is driven, the left and right drive wheels rotate, and the vehicle moves forward or backward.

[0092] In such a motor, when the vehicle engine and motor are not driving, it is desirable that the rotor 4 stop relative to the stator 3 of the drive unit 10 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 stopped 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 is not driving. Therefore, the braking device 50 according to this embodiment employs the configuration described below to increase the detent torque (magnetic attraction torque acting between the magnet 72, the magnetic pole portion 60, and the magnetic body 71 when the coil 33 of the drive unit 10 is in a non-excited state).

[0093] In the braking device 50 of this embodiment, as shown in Figure 12, when the rotor 7 is stopped relative to the stator 6, a magnetic circuit MC2 is formed by the magnet 72 of the rotor 7 between the magnetic body (magnetic pole portion) 71 of the rotor 7 and the magnetic pole portion 60 of the stator 6, and a detent torque (cogging torque) is generated that prevents the rotor 7 from rotating in the circumferential direction C relative to the stator 6, thereby suppressing the rotor 4 from rotating in the circumferential direction C relative to the stator 6.

[0094] In the rotor 7 according to this embodiment, an air gap 71H is disposed adjacent to side surfaces 723, 724 of the magnet 72 shown in FIG. 11 in the circumferential direction C. The magnetic permeability of the air gap 71H is lower than that of the magnetic body 71, so the air gap 71H functions as a flux barrier. Therefore, the magnetic flux from the side surfaces 723, 724 of the magnet 72 in the circumferential direction C is suppressed, while the magnetic flux from the outer end surface 722 of the magnet 72 to the outside in the radial direction R is increased. Note that the air gap 71H may be filled with air or a non-magnetic body (for example, a resin having a magnetic permeability lower than that of the magnetic body, such as the electromagnetic steel sheet, that forms the stator 6).

[0095] Furthermore, in the circumferential direction C of the rotor 7 according to this embodiment, the width W14 of the connecting portion 713 is smaller than the width W13 of the gap 71H (first gap 71H1), and the width W15 of the outer ring 711 in the radial direction R is smaller than the width W13 of the first gap 71H1 in the circumferential direction C. For these reasons, the magnetic flux from the magnet 72 in the circumferential direction C passes through the outer ring 711 and the connecting portion 713. However, due to the above configuration, the magnetic resistance when the magnetic flux from the magnet 72 passes through the outer ring 711 and the connecting portion 713 is greater than the magnetic resistance when the magnetic flux from the magnet 72 passes through the magnetic circuit MC2. As a result, in the rotor 7 according to this embodiment, the magnetic flux from the magnet 72 in the circumferential direction C through the outer ring 711 is suppressed, while the magnetic flux from the outer end face 722 of the magnet 72 directed outward in the radial direction R is increased.

[0096] In the radial direction R of the rotor 7 according to this embodiment, the portions 713a of the two connecting portions 713 that connect to the inner ring 712 are located closer to the inner ring 712 than the inner surface of the magnet 72 that faces the inner ring 712 (i.e., the inner end face 721 of the magnet 72). Therefore, by increasing the length of the connecting portions 713 in the radial direction R, it is possible to increase the magnetic resistance when the magnetic flux of the magnet 72 passes through the outer ring 711 and the connecting portions 713. In particular, the length of the connecting portions 713 in the radial direction R is formed to be longer than the length of the magnet 72. Therefore, in the rotor 7 according to this embodiment, the magnetic flux from the magnet 72 through the outer ring 711 in the circumferential direction C is suppressed, while the magnetic flux from the outer end face 722 of the magnet 72 that flows outward in the radial direction R is increased.

[0097] In the rotor 7 according to this embodiment, the inner ring 712 has a plurality of protrusions 712b that protrude toward the outer ring 711 in the radial direction R, and the protrusions 712b are connected to the magnets 72. As a result, the distance between the outer ring 711 and the inner ring 712 in the radial direction R can be increased by the length of the protrusions 712b in the radial direction R, and the length of the connecting portion 713 in the radial direction R can be increased. As a result, the magnetic resistance when the magnetic flux of the magnet 72 passes through the outer ring 711 and the connecting portion 713 can be increased. Therefore, in the rotor 7 according to this embodiment, the magnetic flux from the magnet 72 passing through the outer ring 711 in the circumferential direction C is suppressed, while the magnetic flux from the outer end face 722 of the magnet 72 directed outward in the radial direction R is increased.

[0098] In the rotor 7 according to this embodiment, the portion 713a of the connecting portion 713 that connects to the inner ring 712 is located closer to the inner ring 712 than the end of the protruding portion 712b that faces the outer ring 711 (the bottom of the recessed portion 712b3). In other words, the portion 713a of the connecting portion 713 that connects to the inner ring 712 is located inward in the radial direction R from the end of the protruding portion 712b that faces the outer ring 711 (the bottom of the recessed portion 712b3). This allows the length of the connecting portion 713 in the radial direction R to be longer. As a result, the magnetic resistance when the magnetic flux of the magnet 72 passes through the outer ring 711 and the connecting portion 713 can be increased. Therefore, in the rotor 7 according to this embodiment, the magnetic flux from the magnet 72 that flows in the circumferential direction C through the outer ring 711 is suppressed, while the magnetic flux that flows outward in the radial direction R from the outer end face 722 of the magnet 72 is increased.

[0099] In the circumferential direction C of the rotor 7 according to this embodiment, the second gap 71H2 is located between the protruding portion 712b and the connecting portion 713. The magnetic permeability of the second gap 71H2 is lower than that of the magnetic body 71, and therefore the second gap 71H2 functions as a flux barrier. Therefore, the magnetic flux from the side surfaces 723 and 724 of the magnet 72 in the circumferential direction C is suppressed, while the magnetic flux from the outer end surface 722 of the magnet 72 to the outside in the radial direction R is increased. Note that the gap 71H2 may be filled with air or a non-magnetic material (for example, a resin having a magnetic permeability lower than that of the magnetic material, such as the electromagnetic steel sheet, that forms the stator 6).

[0100] Based on the various configurations described above, by increasing the magnetic flux directed outward in the radial direction R, it is possible to increase the magnetic flux directed from the outer surface of the magnetic body 71 to the teeth 62 of the stator 6 located outside in the radial direction R, thereby increasing the detent torque.

[0101] In the motor 1 according to this embodiment, the detent torque of the rotor 7 of the braking device 50, which is the second rotor, is greater than the detent torque of the rotor 4 of the driving device 10, which is the first rotor. In addition, the rotors 4 and 7 are spaced apart by a predetermined distance in the axial direction A so that the magnetic forces of the magnets 42 and 72 do not substantially interact with each other.

[0102] In the motor 1 according to the present embodiment described above, the radial dimension R of rotor 4, the first rotor, is the same as the radial dimension R of rotor 7, the second rotor. However, the motor 1 according to the present embodiment is not limited to this. For example, the ratio of the radial dimension R of rotor 4, the first rotor, to the radial dimension R of rotor 7, the second rotor, may be between 0.9 and 1.1.

[0103] As described above, the motor 1 in this embodiment includes the rotor (first rotor) 4 of the drive device 10 and the rotor (second rotor) 7 of the braking device 50, and therefore can improve detent torque.

[0104] As described above, the motor 1 in this embodiment comprises a rotor (first rotor) 4 having a plurality of magnets 42 arranged in the axial direction A, and a rotor (second rotor) 7 having a plurality of magnets 72, the detent torque of the rotor 7 is larger than the detent torque of the rotor 4, the number of the plurality of magnets 42 of the rotor 4 is the same as the number of the plurality of magnets 72 of the rotor 7, and the ratio of the radial dimension R of the rotor 4 to the radial dimension R of the rotor 7 is between 0.9 and 1.1.

[0105] In the motor 1 according to this embodiment, the size of the rotor 4 and the size of the rotor 7 in the radial direction R are the same.

[0106] In the axial direction A of the motor 1 according to this embodiment, the rotor 4 and the rotor 7 are spaced apart by a predetermined distance.

[0107] In the motor 1 of this embodiment, the rotor 4 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 the outer peripheral surfaces (side surfaces) 4112 extending in the circumferential direction C of the two magnetic pole portions 411 are continuous curved surfaces.

[0108] The electronic device 300 according to this embodiment includes the motor 1 described above and a housing 301 that houses the motor 1.

[0109] The electronic device 300 according to this embodiment includes the motor 1 described above and one or more gears 302 and 303.

[0110] [Modification of the first embodiment] Next, a modified stator 6α in the braking device 50 of this embodiment will be described with reference to Figures 14 and 15. Figure 14 is a front view of the modified stator 6α. Figure 15 is an enlarged view of a portion of Figure 14. Note that, in the configuration of the stator 6α according to the modified example, configurations that differ from those of the stator 6 according to the embodiment will be described below, and the same configurations will be assigned the same reference numerals and descriptions thereof will be omitted.

[0111] The teeth 62α of the stator 6α include a main body portion 620 extending in the radial direction R from the inner circumferential surface of the yoke 61, and protrusions 62a, 62b and a recess 62c provided on the inside of the main body portion 620 in the radial direction R. In other words, the inner circumferential surface (side surface) 60f of the magnetic pole portion 60 of the stator 6α facing the rotor 7 in the radial direction R includes two protrusions 62a, 62b protruding toward the rotor 7, and a recess 62c formed between the two protrusions 62a, 62b in the circumferential direction C.

[0112] The pair of protrusions 62a, 62b protrude away from each other in the circumferential direction C, and therefore, when viewed from the axial direction A, protrude outward in the circumferential direction C from the side surface 620f of the main body portion 620 (towards the adjacent other main body portion 620).

[0113] In the radial direction R of the braking device 50α according to this modification, the inner circumferential surface (side surface) 60f of the magnetic pole portion 60 of the stator 6α that faces the rotor 7 includes two protrusions 62a, 62b that protrude toward the rotor 7 and a recess 62c formed between the two protrusions 62a, 62b in the circumferential direction C. The presence of the two protrusions 62a, 62b on one tooth 62α results in the presence of two protrusions 62a, 62b that form the magnetic pole portion 60, and the number of magnetic pole portions is greater than that of a tooth that does not have two protrusions 62a, 62b. Therefore, the braking device 50 according to this modification can further increase the detent torque.

[0114] Next, the magnitude of the cogging torque will be described with reference to Figs. 16-1 to 16-3. Fig. 16-1 is a diagram showing the flow of magnetic flux of the magnet 72 of the rotor 7 relative to the stator 6α and the magnitude of the magnetic flux density when the magnetic body (magnetic pole portion) 71 of the rotor 7 and the teeth 62α of the stator 6α are facing each other. Fig. 16-2 is a diagram showing the waveform of the cogging torque. Fig. 16-3 is a diagram showing the flow of magnetic flux of the magnet 72 of the rotor 7 relative to the stator 6α and the magnitude of the magnetic flux density when the rotor 7 rotates from a state in which the magnetic body (magnetic pole portion) 71 of the rotor 7 and the teeth 62α of the stator 6α are facing each other to a state in which they no longer face each other.

[0115] As can be seen from Figures 16-1 and 16-2, when the magnetic body (magnetic pole portion) 71 of the rotor 7 faces the teeth 62α, which are the magnetic pole portions of the stator 6α, 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.

[0116] On the other hand, as can be seen from Figures 16-2 and 16-3, when the rotor 7 rotates from an opposing state between the magnetic body (magnetic pole portion) 71 of the rotor 7 and the teeth 62α, which are the magnetic pole portions of the stator 6α, to a non-opposing state, 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. Note that, as shown in Figure 16-2, the torque is greatest in the state shown in Figure 16-3.

[0117] [Second embodiment] Next, a second embodiment of the motor 1A according to this embodiment will be described with reference to FIG. 17. FIG. 17 is a perspective view of an electronic device 300A according to the second embodiment. The motor 1A according to this embodiment includes a shaft 2, a drive device 10, and a braking device 50A. Note that the following describes the configuration of the motor 1A according to this embodiment that is different from the motor 1 according to the first embodiment, and the same configuration is designated by the same reference numerals and description thereof will be omitted.

[0118] The braking device 50A includes a stator 6A and a rotor 7A. Next, the rotor 7A will be described with reference to FIGS. 18 to 24. FIG. 18 is an exploded perspective view of the braking device 50A included in the electronic device 300A shown in FIG. 17. FIG. 19 is a perspective view of the magnetic body 41 and the magnet 42 of the rotor 7A included in the braking device 50A shown in FIG. 18. FIG. 20 is a front view of the magnetic body 41 and the magnet 42 shown in FIG. 19. FIG. 21 is an enlarged view of a portion of FIG. 20. FIG. 22 is a cross-sectional view of the rotor 7A shown in FIG. 19. FIG. 23 is a perspective view of the magnetic body 41 included in the rotor 7A shown in FIG. 19. FIG. 24 is an enlarged view of a portion of FIG. 20.

[0119] The rotor 7A 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 configuration of the rotor 7A according to this embodiment is the same as that of the rotor 4 according to the first embodiment, except that the outer peripheral surface 4112A of the magnetic pole portions 411 has recesses and protrusions, which will be described below. The braking device 50A according to this embodiment can increase detent torque by providing the recesses and protrusions.

[0120] In the rotor 7A according to this embodiment, an outer peripheral surface 4112A extending in the circumferential direction C is formed with one or more recesses (hereinafter referred to as recesses DE1) recessed inward in the radial direction R, and one or more protrusions (hereinafter referred to as protrusions PR1) protruding outward in the radial direction R. The outer peripheral surface 4112A extending in the circumferential direction C of the magnetic pole portion 411 is an example of a side surface extending in the circumferential direction C of the magnetic pole portion 411.

[0121] 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.

[0122] 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.

[0123] Next, the recesses and protrusions of the magnetic pole portions 30A of the stator 6A will be described with reference to FIG. 25. FIG. 25 is an enlarged view of the magnetic pole portions 30A of the stator 6A included in the motor 1A shown in FIG. 19. The configuration of the stator 6A according to this embodiment is the same as that of the stator 3 of the first embodiment, except that the inner circumferential surfaces 321A of the teeth 32 are provided with recesses and protrusions, as described below. The brake device 50A according to this embodiment can increase detent torque by providing the recesses and protrusions. The stator 6A is composed of a yoke 31 as an annular portion and teeth 32 as the magnetic pole portions 30A. In the radial direction R of the motor 1A according to this embodiment, the inner circumferential surfaces (side surfaces) 321A of the teeth 32 of the stator 6A face the outer circumferential surfaces (side surfaces) 4112A of the magnetic pole portions 411 of the rotor 7A (see FIG. 26). The inner surface 321A of the tooth 32 extending in the circumferential direction C is formed with one or more recesses (hereinafter referred to as recesses DE2) recessed outward in the radial direction R, and one or more protrusions (hereinafter referred to as protrusions PR2) protruding inward in the radial direction R.

[0124] 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.

[0125] 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.

[0126] Next, the relationship between the recessed portion DE1 and the protruding portion PR1 of the magnetic pole portion 411 in the rotor 4 and the recessed portion DE2 and the protruding portion PR2 of the magnetic pole portion 30 in the stator 3 will be described with reference to Figures 26 and 27. Figure 26 is a plan view of the recessed portion DE1 and the protruding portion PR1 of the magnetic pole portion 411A in the rotor 7A, and the recessed portion DE2 and the protruding portion PR2 of the magnetic pole portion 30A in the stator 6A. Figure 27 is an enlarged view of the recessed portion DE1 and the protruding portion PR1 of the magnetic pole portion 411A in the rotor 7A, and the recessed portion DE2 and the protruding portion PR2 of the magnetic pole portion 30A in the stator 6A.

[0127] As described above, three recesses DE1 and four protrusions PR1 are formed in one magnetic pole portion 411A of the rotor 7A. Meanwhile, three recesses DE2 and four protrusions PR1 are formed in one magnetic pole portion 30A of the stator 6A. In other words, the number of recesses DE1 or protrusions PR1 in one magnetic pole portion 411 of the rotor 7A is the same as the number of recesses DE2 or protrusions PR2 in one magnetic pole portion 30 of the stator 6A.

[0128] Furthermore, in the radial direction R when the vehicle engine and motor 1A are not driving, the recess DE1 of the rotor 7A faces the recess DE2 of the stator 6A, and the protrusion PR1 of the rotor 7A faces the protrusion PR2 of the stator 6A.

[0129] For example, as shown in Figure 27, in the radial direction R, the first recess DE1a of the rotor 7A faces the first recess DE2a of the stator 6A, the second recess DE1b of the rotor 7A faces the second recess DE2b of the stator 6A, and the third recess DE1c of the rotor 7A faces the third recess DE2c of the stator 6A.

[0130] Furthermore, in the radial direction R, the first protrusion PR1a of the rotor 7A faces the first protrusion PR2a of the stator 6A, the second protrusion PR1b of the rotor 7A faces the second protrusion PR2b of the stator 6A, the third protrusion PR1c of the rotor 7A faces the third protrusion PR2c of the stator 6A, and the fourth protrusion PR1d of the rotor 7A faces the fourth protrusion PR2d of the stator 6A.

[0131] Also, as shown in Figure 26, when four protrusions PR1 in one magnetic pole portion 411A of the rotor 7A face four protrusions PR2 in one magnetic pole portion 30A of the stator 6A in the radial direction R, in the magnetic pole portion 411A adjacent to that magnetic pole portion 411A in the circumferential direction C, three protrusions PR1 of the rotor 7A face three protrusions PR2 of the stator 6A in the radial direction R.

[0132] Furthermore, in the motor 1A of this embodiment, when the four protrusions PR1 of one magnetic pole portion 411A of the rotor 7A and the four protrusions PR2 of one magnetic pole portion 411A of the stator 6A are opposed to each other in the radial direction R, at least two protrusions PR1 of the rotor 7A and two protrusions PR2 of the stator 6A are opposed to each other in the radial direction R between the remaining one magnetic pole portion 411A of the rotor 7A and one magnetic pole portion 30A of the stator 6A. As shown in Figure 27, the convex portion PR1 of the rotor 7A and the convex portion PR2 of the stator 6A, which are opposed to each other in the radial direction R, form a magnetic circuit MC3 (see Figure 27) that passes through the convex portion PR1 of the magnetic pole portion 411A of the rotor 7A and the convex portion PR2 of the magnetic pole portion 30A of the stator 6A, and also passes through the magnetic pole portion 411A of the rotor 7A having the convex portion PR1 and the magnetic pole portion 30A of the stator 6A having the convex portion PR2, based on the magnetic force of the magnet 42 of the rotor 7A.

[0133] For these reasons, when the vehicle engine and motor 1A are not driven, a magnetic circuit MC3 is formed between the magnetic pole portion 411A of the rotor 7A and the magnetic pole portion 30A of the stator 6A by the magnet 42 of the rotor 7A, passing through the convex portion PR1 of the rotor 7A and the convex portion PR2 of the stator 6A, and a detent torque (cogging torque) is generated that prevents the rotor 7A from rotating in the circumferential direction C relative to the stator 6A.

[0134] Next, the magnetization of the magnets 42 of the rotor (first rotor) 4 of the driving device 10A and the magnetization of the magnets 72 of the rotor (second rotor) 7A of the braking device 50A will be described with reference to FIG. 28. FIG. 28 is a schematic diagram showing the magnetization of the magnets 42 of the rotor 4 of the driving device 10A and the magnetization of the magnets 72 of the rotor 7A of the braking device 50A. As described above, the dimension of the rotor 4 in the radial direction R is the same as the dimension of the rotor 7A in the radial direction R. Furthermore, the number of the multiple magnets 42 of the rotor 4 is the same as the number of the multiple magnets 42 of the rotor 7A. Furthermore, the number of poles of the multiple magnets 42 of the rotor 4 is the same as the number of poles of the multiple magnets 42 of the rotor 7A.

[0135] Then, for example, after fixing the rotors 4 and 7A to the shaft 2, the positions of the magnets 42 of the rotor 4 and the positions of the magnets 42 of the rotor 7A are aligned in the axial direction A. At this time, the rotors 4 and 7A are arranged apart from each other by a predetermined distance L3 in the axial direction A.

[0136] Then, the magnetizing device 200 is disposed radially outside the rotor 4. The magnetizing device 200 is formed in a ring shape (annular shape) when viewed from the axial direction A, and the inner peripheral dimension in the radial direction R is slightly larger than the outer peripheral dimension of the rotor 4 of the drive device 10 and slightly larger than the outer peripheral dimension of the rotor 7A of the braking device 50. The magnetizing device includes a magnetizing yoke 201 having a coil (not shown), and a power supply electrically connected to the coil. The magnetizing device 200 forms a magnetic field in the coil by applying a voltage from the power supply, and the formed magnetic field magnetizes the magnets 42 of the rotor 4 and also magnetizes the magnets 42 of the rotor 7A.

[0137] Therefore, in the axial direction A, radial direction R, and circumferential direction C of the motor 1A according to this embodiment, the positions of the south and north poles of the magnet 42 formed on the rotor 4 of the drive device 10 are the same as the positions of the south and north poles of the magnet 42 formed on the rotor 7A of the braking device 50A. Therefore, in the motor 1A according to this embodiment, the magnet 42 of the rotor 4 of the drive device 10 and the magnet 42 of the rotor 7A of the braking device 50A can be magnetized together by a single magnetizing yoke 201.

[0138] As a result, in the motor 1A according to this embodiment, the magnet 42 of the rotor 4 of the drive device 10 and the magnet 42 of the rotor 7A of the brake device 50A can be magnetized simultaneously, thereby reducing the number of steps required. Therefore, by reducing the number of steps required, the motor 1A according to this embodiment can reduce the amount of foreign matter adhering to the magnet 42 of the rotor 4 of the drive device 10, and can also reduce the amount of foreign matter adhering to the magnet 42 of the rotor 7A of the brake device 50A. In addition, the magnetization yoke 201 of the magnetization device 200 can be reduced to one. Furthermore, in the motor 1A according to this embodiment, mutual interference during magnetization between the magnet 42 of the rotor 4 of the drive device 10 and the magnet 42 of the rotor 7A of the brake device 50A can be suppressed, and incorrect polarity of the magnet 42 can be prevented.

[0139] In the motor 1A according to this embodiment, the detent torque of the rotor 7A of the braking device 50A, which is the second rotor, is greater than the detent torque of the rotor 4 of the driving device 10, which is the first rotor. In addition, the rotors 4 and 7A are spaced apart by a predetermined distance in the axial direction A so that the magnetic force of the magnet 42 of the rotor 4 of the driving device 10 and the magnetic force of the magnet 72 of the rotor 7A of the braking device 50A do not substantially interact with each other.

[0140] In the motor 1A according to the present embodiment described above, the radial dimension R of the rotor 4 (first rotor) is the same as the radial dimension R of the rotor 7A (second rotor). However, the motor 1A according to the present embodiment is not limited to this. For example, the ratio of the radial dimension R of the rotor 4 (first rotor) to the radial dimension R of the rotor 7A (second rotor) may be between 0.9 and 1.1.

[0141] The rotor (second rotor) 7A of this embodiment comprises a magnetic body 41A having two magnetic pole portions 411A, an annular portion 412, and two connecting portions 413 connecting the two magnetic pole portions 411A and the annular portion 412, and a magnet 42 located between the two magnetic pole portions 411A in the circumferential direction C, and a plurality of recesses (concave) DE1 or protrusions (convex) PR1 are formed on the outer peripheral surface (side surface) 4112A extending circumferentially of the two magnetic pole portions 411A.

[0142] The braking device 50A of this embodiment has a stator (second stator) 6A that faces a rotor (second rotor) 7A in the radial direction R, and the stator 6A has a plurality of magnetic pole portions 30A, and a plurality of recesses (concave) DE2 or protrusions (protrusions) PR2 are formed on the inner surface (side surface) 321A of the magnetic pole portions 30A that faces the outer peripheral surface (side surface) 4112A of the rotor 7A in the radial direction R.

[0143] In the braking device 50A according to this embodiment, the number of recesses DE1 or protrusions PR1 of the rotor 7A is the same as the number of recesses DE2 or protrusions PR2 of the stator 6A.

[0144] In the above-described motors 1 and 1A, the rotors 4, 7, and 7A are merely examples, and other types of rotors or stators can be applied as long as the ratio of the radial dimension R of the rotor 4 of the drive device 10 to the radial dimension R of the rotors 7 and 7A of the braking devices 50 and 50A is between 0.9 and 1.1, and the detent torque of the rotors 7 and 7A relative to the stators 6 and 6A of the braking devices 50 and 50A is greater than the detent torque of the rotor 4 relative to the stator 3 of the drive device 10.

[0145] Furthermore, in the above-described first embodiment, the modified example of the first embodiment, and the second embodiment, the motors 1 and 1A are described as being applied to a vehicle. However, the motors 1 and 1A according to the present invention are not limited to this and can be used in other appliances and devices.

[0146] Although the present invention has been described above based on the first embodiment, a modified version of the first embodiment, and a second embodiment, it goes without saying that the present invention is not limited to the embodiments and modifications, and various modifications are possible without departing from the gist of the present invention. Such modifications without departing from the gist 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]

[0147] 1, 1A motor, 3, 6A stator, 30A magnetic pole portion, 321A inner peripheral surface, 4 rotor (first rotor), 41, 41A magnetic body, 411, 411A magnetic pole portion, 4112, 4112A outer peripheral surface, 412 annular portion, 413 connection portion, 42 magnet, 7, 7A rotor (second rotor), 72 magnet, 300 electronic device, 301 housing, 302, 303 gear, A axial direction, C circumferential direction, DE1 concave portion (concave), DE2 concave portion (concave), R radial direction, PR1 convex portion (convex), PR2 convex portion (convex)

Claims

1. a first rotor having a plurality of magnets arranged in an axial direction, and a second rotor having a plurality of magnets; a detent torque of the second rotor is greater than that of the first rotor; A motor, wherein the number of magnets in the first rotor is the same as the number of magnets in the second rotor.

2. 2. The motor of claim 1, wherein a ratio of a size of the first rotor to a size of the second rotor is between 0.9 and 1.

1.

3. 3. The motor according to claim 1, wherein the first rotor and the second rotor have the same size.

4. The motor according to claim 1 , wherein the first rotor and the second rotor are spaced apart from each other by a predetermined distance in the axial direction.

5. The first rotor is 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 The motor according to claim 1 , wherein the side surfaces of the two magnetic pole portions extending in the circumferential direction are continuous curved surfaces.

6. The second rotor is 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 The motor according to claim 1 , wherein a plurality of recesses or protrusions are formed on the circumferentially extending side surfaces of the two magnetic pole portions.

7. a stator facing the second rotor in a radial direction, the stator includes a plurality of magnetic pole portions, The motor according to claim 1 , wherein a plurality of recesses or protrusions are formed on a side surface of the magnetic pole portion that faces a side surface of the second rotor in the radial direction.

8. The motor according to claim 7 , wherein the number of the plurality of recesses or protrusions of the second rotor is the same as the number of the plurality of recesses or protrusions of the stator.

9. An electronic device comprising: the motor according to any one of claims 1 to 7; and a housing that houses the motor.

10. An electronic device comprising the motor according to any one of claims 1 to 7 and one or more gears.

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