Rotor, controller, and electronic apparatus

Abstract

To provide a rotor which can increase a detent torque.SOLUTION: A rotor includes: an outside ring; an inside ring; a magnetic body with a plurality of connection parts connecting the outside ring and the inside ring to each other; a plurality of magnets; and two gaps between two of the connection parts on both sides of the magnet and the magnet in the circumferential direction. The connection parts are narrower than the gap in the circumferential direction.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a rotor, a braking device, 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] Japanese Patent Application Laid-Open No. 2017-63599 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 braking device, and an electronic device that can increase detent torque. [Means for solving the problem]

[0006] In one embodiment, the rotor includes a magnetic body having an outer ring, an inner ring, and a plurality of connecting portions connecting the outer ring and the inner ring, a plurality of magnets, and two gaps between the magnets and two connecting portions on both sides of the magnets in the circumferential direction, where the width of the connecting portions is smaller than the width of the gaps 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] 2 is an exploded perspective view of a braking device included in the electronic device shown in FIG. [Figure 3] 3 is a perspective view of the magnetic body and magnet of the rotor provided in the braking device 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 front view showing the magnetic circuits formed in the stator and rotor. [Figure 7] FIG. 7 is a cross-sectional view of the stator and rotor shown in FIG. [Figure 8] FIG. 8 is a front view of a modified stator. [Figure 9] FIG. 9 is an enlarged view of a portion of FIG. [Figure 10] FIG. 10 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 11] FIG. 11 is a diagram showing the waveform of the cogging torque. [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 rotor rotates from a facing state where the magnetic body of the rotor and the teeth of the stator are no longer facing each other. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Embodiment] The braking device 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 braking device 1 in this embodiment is housed in, for example, electronic device 300 as shown in Fig. 1. Fig. 1 is a perspective view of electronic device 300 according to this embodiment. In explaining the braking device 1 according to this embodiment, to facilitate understanding of directions, the direction in which shaft 2 extends will be referred to as axial direction A, the direction in which rotor 4 rotates will be referred to as circumferential direction C, and the direction that is included in a plane perpendicular to axial direction A, passes through axis center 2o of shaft 2, and is perpendicular to circumferential direction C will be referred to as 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 braking device 1, a housing 301 that houses the braking device 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 braking device 1. The shaft 2 rotates in conjunction with, for example, a rotor in a driving motor. 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 rotor of the driving motor is transmitted to the output shaft 304 of the electronic device 300 via the shaft 2.

[0013] Next, the braking device 1 will be described with reference to Figures 1 and 2. Figure 2 is an exploded perspective view of the braking device 1 provided in the electronic device 300 shown in Figure 1. The braking device 1 in this embodiment includes a shaft 2, a stator 3, and a rotor 4. Note that in the braking device 1 according to this embodiment, for example, the stator 3 is located outside the 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 and teeth 32 as magnetic pole portions 30. The stator 3 according to this embodiment is composed of electrically non-connected members. The yoke 31 and the teeth 32 are made of a magnetic material.

[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. In this embodiment, no coils are provided on the teeth 32. The multiple teeth 32 are arranged at equal intervals in the circumferential direction C, for example. 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 the multiple members in the axial direction A.

[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 has a magnetic body 41, a magnet 42, and a pair of covers 43.

[0018] The rotor 4 according to this embodiment is a so-called IPM (Interior Permanent Magnet) rotor that is composed of a plurality of magnets 42 arranged along the circumferential direction C and a magnetic body 41 that houses the plurality of magnets 42, and the plurality of magnets 42 are arranged radially. The outer size (outer diameter) of the rotor 4 according to this embodiment is, for example, 24.5 mm.

[0019] 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 braking device 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. Figure 6 is a front view showing the magnetic circuit MC formed in the stator 3 and the rotor 4.

[0020] The multiple magnets 42 are arranged at equal intervals in the circumferential direction C, for example. The magnets 42 in this embodiment are permanent magnets extending in the axial direction A, for example. The magnets 42 are sintered magnets, for example. The magnets 42 are located between the two connecting portions 413 in the circumferential direction C. More specifically, the magnets 42 are located between the two connecting portions 413 in the circumferential direction C, with two gaps 41H interposed therebetween. The magnets 42 are 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, 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.

[0022] 6, for example, one magnet 42 of the multiple magnets 42 of the rotor 4 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 42 adjacent to that magnet 42 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 42 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.

[0023] Next, the pair of covers 43 will be described with reference to Figures 2 and 7. Figure 7 is a cross-sectional view of the stator 3 and 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. Alternatively, the cover 43 may be made 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 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 includes a main body portion 431 formed in a flat ring shape, and an inner peripheral portion 432 that protrudes in the axial direction A from the main body portion 431 at its inner peripheral edge in the radial direction R.

[0027] 2 and 7, the inner circumferential portion 432 of one cover 43a protrudes from the inner circumferential edge of the main body portion 431 toward the inner circumferential portion 432 of the other cover 43b in the axial direction A. The inner circumferential portion 432 is formed, for example, in a cylindrical shape. Moreover, the inner circumferential portion 432 faces the inner circumferential surface of the inner ring 412 of the magnetic body 41 and is disposed so as to be in contact with the inner ring 412.

[0028] 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.

[0029] 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 an outer ring 411, an inner ring 412, and a plurality of connecting portions 413 that connect the outer ring 411 and the inner ring 412. In the rotor 4 according to the embodiment, the magnetic body 41 forms a magnetic pole portion.

[0030] The outer ring 411 is formed in an annular shape when viewed from the axial direction A. The outer ring 411 is disposed outward of the inner ring 412 in the radial direction R. The outer ring 411 is also disposed outward of the magnet 42 in the radial direction R, and is in contact with the outer end face 422 of the magnet 42. This prevents the magnet 42 from moving outward in the radial direction R when the rotor 4 rotates.

[0031] The inner ring 412 is formed in an annular shape when viewed from the axial direction A. The inner ring 412 is disposed inside the outer ring 411 in the radial direction R. The inner ring 412 is disposed inside the magnet 42 in the radial direction R and is in contact with the inner end face 421 of the magnet 42. This prevents the magnet 42 from moving inward in the radial direction R. The inner ring 412 includes an annular portion 412a and a plurality of protrusions 412b that protrude from the annular portion 412a toward the outer ring 411 in the radial direction R.

[0032] The shaft 2 is disposed inside the annular portion 412a in the radial direction R (see FIG. 2). Each of the protrusions 412b is connected to a magnet 42. The multiple protrusions 412b are disposed at predetermined intervals (e.g., equal intervals), for example, in the circumferential direction C. The inner ring 412 in this embodiment includes, for example, 12 protrusions 412b.

[0033] The protrusion 412b engages the magnet 42 with the inner ring 412, and has a pair of convex portions 412b1 and 412b2 spaced apart in the circumferential direction C, and a concave portion 412b3 located between the pair of convex portions 412b1 and 412b2 in the circumferential direction C. In the present embodiment, the bottom of the concave portion 412b3 is an example of an end portion of the protrusion 412b located on the outer side in the radial direction R.

[0034] The connecting portions 413 connect the outer ring 411 and the inner ring 412. The connecting portions 413 are arranged at equal intervals, for example, in the circumferential direction C. The magnetic body 41 in this embodiment includes, for example, 12 connecting portions 413.

[0035] 5, the connecting portion 413 has an end portion (portion 413a) located on the inside in the radial direction R and an end portion (portion 413b) located on the outside in the radial direction R. The connecting portion 413 is connected to the inner ring 412 by the end portion (portion 413a), and is connected to the outer ring 411 by the end portion (portion 413b).

[0036] Furthermore, the magnetic body 41 has, in the circumferential direction C, two gaps 41H between the magnet 42 and two of the multiple connecting portions 413 on both sides of the magnet 42.

[0037] Each of the gaps 41H has a first gap 41H1 located on the outer side in the radial direction R and a second gap 41H2 located on the inner side in the radial direction R. In the circumferential direction C, the first gap 41H1 is located between the magnet 42 and the connecting portion 413. In addition, in the circumferential direction C, the second gap 41H2 is located between the protruding portion 412b and the connecting portion 413. In the circumferential direction C of the braking device 1 according to this embodiment, the width W3 of the first gap is larger than the width of the second gap 41H2 and smaller than the width W2 of the tooth 32 (see FIG. 2) and the width of the protruding portion 412b.

[0038] A portion 413a of the connecting portion 413 that connects to the inner ring 412 is located on the inner ring 412 side relative to the end of the outer ring 411 of the protruding portion 412b (the bottom of the recess 412b3).

[0039] Next, a case where the brake device 1 according to this embodiment is used as a brake device for a vehicle will be described. A rotor of a drive motor is fixed to the shaft 2 of the brake device 1 described above, and the shaft 2 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 drive motor is transmitted to the differential gear and then distributed and transmitted from the differential gear to drive wheels consisting of 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.

[0040] In such a motor, when the vehicle engine and motor are not driving, it is desirable that the rotor stop relative to the stator of the drive motor 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 such a motor have an increased detent torque (cogging torque) when not driving. Therefore, the braking device 1 according to this embodiment can increase the detent torque by employing the configuration described below.

[0041] In the braking device 1 of this embodiment, as shown in Figure 6, when the rotor 4 is stopped relative to the stator 3, a magnetic circuit MC is formed by the magnet 42 of the rotor 4 between the magnetic body (magnetic pole portion) 41 of the rotor 4 and the magnetic pole portion 30 of the stator 3, and a detent torque (cogging torque) is generated, thereby suppressing the rotation of the rotor 4 in the circumferential direction C relative to the stator 3.

[0042] In the rotor 4 according to this embodiment, an air gap 41H is disposed adjacent to the side surfaces 423, 424 of the magnet 42 shown in FIG. 5 in the circumferential direction C. The magnetic permeability of the air gap 41H is lower than that of the magnetic body 41, so the air in the air gap 41H functions as a flux barrier. Therefore, the magnetic flux from the side surfaces 423, 424 of the magnet 42 in the circumferential direction C is suppressed, while the magnetic flux from the outer end surface 422 of the magnet 42 to the outside in the radial direction R is increased. Note that air or a non-magnetic body (for example, a resin having a magnetic permeability lower than that of the magnetic body 41, such as an electromagnetic steel sheet, that forms the stator 3) may be present in the air gap 41H.

[0043] Furthermore, in the circumferential direction C of the rotor 4 according to this embodiment, the width W4 of the connecting portion 413 is smaller than the width W3 of the gap 41H (first gap 41H1), and the width W5 of the outer ring 411 in the radial direction R is smaller than the width W3 of the first gap 41H1 in the circumferential direction C. For these reasons, the magnetic flux from the magnet 42 in the circumferential direction C passes through the outer ring 411 and the connecting portion 413, but due to the above configuration, the magnetic resistance when the magnetic flux from the magnet 42 passes through the outer ring 411 and the connecting portion 413 is greater than the magnetic resistance when the magnetic flux from the magnet 42 passes through the magnetic circuit MC. As a result, in the rotor 4 according to this embodiment, the magnetic flux from the magnet 42 through the outer ring 411 in the circumferential direction C is suppressed, while the magnetic flux from the outer end face 422 of the magnet 42 directed outward in the radial direction R is increased.

[0044] In the radial direction R of the rotor 4 according to this embodiment, the portions 413a of the two connecting portions 413 that connect to the inner ring 412 are located closer to the inner ring 412 than the inner surface of the magnet 42 that faces the inner ring 412 (i.e., the inner end face 421 of the magnet 42). Therefore, by increasing the length of the connecting portions 413 in the radial direction R, it is possible to increase the magnetic resistance when the magnetic flux of the magnet 42 passes through the outer ring 411 and the connecting portions 413. In particular, the length of the connecting portions 413 in the radial direction R is formed to be longer than the length of the magnet 42. Therefore, in the rotor 4 according to this embodiment, the magnetic flux from the magnet 42 through the outer ring 411 in the circumferential direction C is suppressed, while the magnetic flux from the outer end face 422 of the magnet 42 that flows outward in the radial direction R is increased.

[0045] In the radial direction R of the rotor 4 according to this embodiment, the inner ring 412 has a plurality of protrusions 412b that protrude toward the outer ring 411, and the protrusions 412b are connected to the magnets 42. As a result, the distance between the outer ring 411 and the inner ring 412 in the radial direction R can be increased by the length of the protrusions 412b in the radial direction R, and the length of the connecting portion 413 in the radial direction R can be increased. As a result, the magnetic resistance when the magnetic flux of the magnet 42 passes through the outer ring 411 and the connecting portion 413 can be increased. Therefore, in the rotor 4 according to this embodiment, the magnetic flux from the magnet 42 through the outer ring 411 in the circumferential direction C is suppressed, while the magnetic flux from the outer end face 422 of the magnet 42 directed outward in the radial direction R is increased.

[0046] In the rotor 4 according to this embodiment, the portion 413a of the connecting portion 413 that connects to the inner ring 412 is located closer to the inner ring 412 than the end of the protruding portion 412b that faces the outer ring 411 (the bottom of the recessed portion 412b3). In other words, the portion 413a of the connecting portion 413 that connects to the inner ring 412 is located more inward in the radial direction R than the end of the protruding portion 412b that faces the outer ring 411 (the bottom of the recessed portion 412b3). This allows the length of the connecting portion 413 in the radial direction R to be longer. As a result, the magnetic resistance when the magnetic flux of the magnet 42 passes through the outer ring 411 and the connecting portion 413 can be increased. Therefore, in the rotor 4 according to this embodiment, the magnetic flux from the magnet 42 that flows in the circumferential direction C through the outer ring 411 is suppressed, while the magnetic flux that flows from the outer end face 422 of the magnet 42 outward in the radial direction R is increased.

[0047] In the circumferential direction C of the rotor 4 according to this embodiment, the second gap 41H2 is located between the protruding portion 412b and the connecting portion 413. The magnetic permeability of the second gap 41H2 is lower than that of the magnetic body 41, and therefore the second gap 41H2 functions as a flux barrier. Therefore, the magnetic flux from the side surfaces 423 and 424 of the magnet 42 in the circumferential direction C is suppressed, while the magnetic flux from the outer end surface 422 of the magnet 42 to the outside in the radial direction R is increased. Note that the gap 41H may be filled with air or a non-magnetic material (for example, a resin having a magnetic permeability lower than that of the magnetic body 41, such as an electromagnetic steel sheet, that forms the stator 3).

[0048] 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 41o of the magnetic body 41 to the teeth 32 of the stator 3 located outside the radial direction R, thereby increasing the detent torque.

[0049] As described above, the rotor 4 in this embodiment comprises a magnetic body 41 having an outer ring 411, an inner ring 412, and a plurality of connecting portions 413 connecting the outer ring 411 and the inner ring 412, a plurality of magnets 42, and, in the circumferential direction C, two connecting portions 413 on either side of the magnet 42 among the plurality of connecting portions 413 and two gaps 41H between the magnet 42 and the magnet 42, and in the circumferential direction C, the width W4 of the connecting portion 413 is smaller than the width W3 of the gap 41H (first gap 41H1).

[0050] In the rotor 4 according to this embodiment, the width W5 of the outer ring 411 in the radial direction R is smaller than the width W3 of the gap 41H (first gap 41H1) in the circumferential direction C.

[0051] In the rotor 4 according to this embodiment, in the radial direction R, portions 413a of the two connecting portions 413 that connect to the inner ring 412 are on the inner ring 412 side relative to the inner surface of the magnet 42 on the inner ring 412 side.

[0052] In the rotor 4 according to this embodiment, the inner ring 412 has a plurality of protrusions 412b that protrude toward the outer ring 411 in the radial direction R, and the protrusions 412b are connected to the magnets .

[0053] In the rotor 4 according to this embodiment, the portion 413a of the connecting portion 413 that connects to the inner ring 412 is located on the inner ring 412 side relative to the end of the outer ring 411 of the protruding portion 412b (the bottom of the recess 412b3).

[0054] The rotor 4 of this embodiment has a first gap 41H1 as the gap 41H and a second gap 41H2 located on the inside in the radial direction R, and in the circumferential direction C, the second gap 41H2 is located between the protrusion 412b and the connecting portion 413.

[0055] In the rotor 4 according to this embodiment, the magnet 42 is sandwiched between the outer ring 411 and the inner ring 412 in the radial direction R, so that the magnet 42 can be held to the magnetic body 41 without using adhesive. Therefore, the rotor 4 according to this embodiment can use a sintered magnet with a high residual magnetic flux density (Br) for the magnet 42, and therefore can increase the detent torque compared to a rotor that uses another magnet for the magnet 42 and has the same size in the radial direction R.

[0056] The electronic device 300 according to this embodiment includes a braking device 1 and a housing 301 that houses the braking device 1.

[0057] The electronic device 300 according to this embodiment includes a braking device 1 and one or more gears 302 and 303.

[0058] [Variations] Next, a modified stator 3A in the braking device 1 of this embodiment will be described with reference to Figures 8, 9, and 10. Figure 8 is a front view of the modified stator 3A. Figure 9 is an enlarged view of a portion of Figure 8. Figure 10 is a front view showing the position of the teeth 32A at which the detent torque is maximized. Note that, in the configuration of the stator 3A according to this modification, configurations that differ from those of the stator 3 according to this embodiment will be described below, and the same configurations will be assigned the same reference numerals and descriptions thereof will be omitted.

[0059] The teeth 32A of the stator 3A include a main body portion 320 extending in the radial direction R from the inner circumferential surface of the yoke 31, and protrusions 32a, 32b and a recess 32c provided on the inside of the main body portion 320 in the radial direction R. In other words, the inner circumferential surface (side surface) 30f of the magnetic pole portion 30 of the stator 3A facing the rotor 4 in the radial direction R includes two protrusions 32a, 32b protruding toward the rotor 4, and a recess 32c formed between the two protrusions 32a, 32b in the circumferential direction C.

[0060] The pair of protrusions 32a, 32b protrude away from each other in the circumferential direction C, and therefore, when viewed from the axial direction A, protrude from the side surface 320f of the main body portion 320 in the circumferential direction C (towards the adjacent other main body portion 320).

[0061] In the radial direction R of the brake device 1 according to this modification, the inner circumferential surface (side surface) 30f of the magnetic pole portion 30 of the stator 3A facing the rotor 4 includes two protrusions 32a, 32b protruding toward the rotor 4 and a recess 32c formed between the two protrusions 32a, 32b in the circumferential direction C. The presence of the two protrusions 32a, 32b on one tooth 32A results in the presence of two protrusions 32a, 32b that form the magnetic pole portion 30, and the number of magnetic pole portions 30 is greater than that of a tooth 32 that does not have two protrusions 32a, 32b. Therefore, the brake device 1 according to this modification can further increase the detent torque.

[0062] In the braking device 1 according to this modification, the outer peripheral surface 41o of the rotor 4 may be provided with the same number of recesses and protrusions as the number of recesses 32c and protrusions 32a, 32b provided on the inner peripheral surface 30f of the teeth 32A of the stator 3A.

[0063] Next, the magnitude of the cogging torque will be described with reference to Figs. 10 to 12. Fig. 10 is a diagram showing the flow of magnetic flux of magnet 42 of rotor 4 relative to stator 3A and the magnitude of magnetic flux density when magnetic body (magnetic pole portion) 41 of rotor 4 and teeth 32A of stator 3A are facing each other. Fig. 11 is a diagram showing the waveform of cogging torque. Fig. 12 is a diagram showing the flow of magnetic flux of magnet 42 of rotor 4 relative to stator 3A and the magnitude of magnetic flux density when rotor 4 rotates from a state where magnetic body (magnetic pole portion) 41 of rotor 4 and teeth 32A of stator 3A are facing each other to a state where they no longer face each other.

[0064] As can be seen from Figures 10 and 11, when the magnetic body (magnetic pole portion) 41 of the rotor 4 faces the teeth 32, which are the magnetic pole portions of the stator 3, 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.

[0065] 11 and 12, when the rotor 4 rotates from an opposing state between the magnetic bodies (magnetic pole portions) 41 of the rotor 4 and the teeth 32, which are the magnetic pole portions of the stator 3, 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. As shown in Fig. 11, the torque becomes largest in the state shown in Fig. 12.

[0066] Furthermore, in the brake device 1 according to this modification, the number MA of magnets 42 on the rotor 4 is 12, and the number TE of teeth 32A on the stator 3A is 12. That is, in the brake device 1 according to this modification, the number MA of magnets 42 on the rotor 4 and the number TE of teeth 32A on the stator 3A are the same. However, if one of them were 10 and the other were 12, the least common multiple would be 60. In this case, in the brake device 1 according to this modification, the cogging torque (detent torque) increases at 60 positions, which is the least common multiple of the number MA of magnets 42 and the number TE of teeth 32A, out of 360 degrees in the circumferential direction C. This is called a cogging ripple (wave). In the cogging ripple, the period of one wave is 6 (degrees / 1), which is obtained by dividing 360 degrees by 60.

[0067] In other words, if the number of magnets 42 of the rotor 4 is MA, the number of teeth 32A of the stator 3A is TE, and the least common multiple of MA and TE 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 intensive studies conducted by the present inventors, the cogging torque can be increased by arranging at least one recess 32c and two protrusions 32a, 32b in correspondence with the period (one wave) of the cogging ripple. For example, in the braking device 1 according to this modification, the cogging torque can be increased by arranging two protrusions 32a, 32b and one recess 32c in correspondence with the period (one wave) of the cogging ripple. In other words, in the braking device 1 according to this modified example, when the least common multiple of the numbers MA and TE is X, at least one recess 32c and two protrusions 32a, 32b are arranged on the inner peripheral surface (side surface) 30f of the teeth 32 so as to correspond to the period of the cogging ripple for every angle obtained by dividing 360 degrees by X, and it is preferable to provide similar recesses and protrusions on the outer peripheral surface (side surface) of the rotor 4.

[0068] In the braking device 1 according to this modification, when the outer size (outer diameter) of the rotor 4 is φ24.5 mm, one recess 32c and two protrusions 32a, 32b are alternately arranged on the inner circumferential surface (side surface) 30f of the teeth 32, which are the magnetic pole portions 30 of the stator 3 facing the rotor 4, so that the recess 32c and the protrusions 32a, 32b can be arranged to match the shape of the cogging ripple. Furthermore, it is preferable to alternately arrange one recess and two protrusions on the outer circumferential surface (side surface) 41o of the magnetic body (magnetic pole portion) 41 of the rotor 4 facing the stator 3. By arranging the recess and the protrusion in this manner, the cogging torque can be further improved by arranging the recess and the protrusion on the outer circumferential surface 41o of the rotor 4 in accordance with the shape of the cogging ripple.

[0069] In other words, the cogging torque can be improved by matching the waveform of the cogging ripple formed by the teeth combination with the shape (one recess 32c and two protrusions 32a, 32b) of the inner circumferential surface (side surface) 30f of the teeth 32A, which are magnetic pole portions 30 of the stator 3A. Furthermore, forming recesses and protrusions on the outer circumferential surface 41o of the rotor 4 in accordance with the waveform of the cogging ripple formed by the teeth combination is preferable in terms of improving the cogging torque.

[0070] In other words, in the braking device 1 according to this modified example, when the number MA of the magnets 42 of the rotor 4 is different from the number of the teeth 32A of the stator 3A, and the least common multiple of the number MA of the magnets 42 of the rotor 4 and the number TE of the teeth 32A of the stator 3 is X, at least one recess 32c and one protrusion 32a, 32b are arranged on the inner circumferential surface (side surface) 30f of the teeth 32 for every angle obtained by dividing 360 degrees by X.

[0071] In the above-described embodiment and modified examples, the rotor 4 of the braking device 1 and the rotor of the drive motor are fixed to the same shaft 2. However, the invention according to this embodiment is not limited to this, and the shaft 2 to which the rotor 4 of the braking device 1 is fixed and the shaft to which the rotor of the drive motor is fixed may be provided separately.

[0072] Furthermore, in the above-described embodiment and modified examples, the braking device 1 applied to a vehicle has been described. However, the braking device 1 according to the present invention is not limited to this and can be used in other devices and apparatuses.

[0073] While the present invention has been described above based on the embodiments and modifications, 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 spirit of the present invention. Such modifications 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]

[0074] 1 braking device, 3, 3A stator, 30 magnetic pole portion, 32A teeth, 32a, 32b protrusions, 32c recesses, 4 rotor, 41 magnetic material, 411 outer ring, 412 inner ring, 413 connecting portion, 41H air gap, 41H1 first air gap, 41H2 second air gap, 42 magnet, 300 electronic device, 301 housing, 302, 303 gear, A axial direction, C circumferential direction, R radial direction, W3 width of first air gap, W4 width of connecting portion, W5 width of outer ring

Claims

1. a magnetic body having an outer ring, an inner ring, and a plurality of connecting portions connecting the outer ring and the inner ring; Several magnets and In the circumferential direction, two gaps are present between two of the connecting portions on both sides of the magnet and the magnet; and Equipped with In the circumferential direction, the width of the connecting portion is smaller than the width of the gap. Rotor.

2. The rotor of claim 1 , wherein a width of the outer ring in the radial direction is smaller than a width of the air gap in the circumferential direction.

3. 3. The rotor according to claim 2, wherein the portions of the two connecting portions that connect to the inner ring in the radial direction are located on the inner ring side with respect to the inner surface of the magnet on the inner ring side.

4. the inner ring has a plurality of protrusions that protrude radially toward the outer ring; The rotor according to claim 1 or 2, wherein the protrusion is connected to the magnet.

5. 5. The rotor of claim 4, wherein the portion of the coupling that couples to the inner ring is on the inner ring side relative to the outer ring end of the projection.

6. a first gap as the gap and a second gap located radially inward of the first gap in the radial direction, The rotor according to claim 4 , wherein the second gap is located between the protrusion and the connecting portion in the circumferential direction.

7. The rotor according to claim 1; a stator having a plurality of magnetic pole portions; A braking device comprising:

8. 8. The braking device according to claim 7, wherein a side surface of the magnetic pole portion of the stator facing the rotor in the radial direction includes two protruding portions protruding toward the rotor and a recessed portion formed between the two protruding portions in the circumferential direction.

9. When the number of the magnets of the rotor is different from the number of teeth of the stator, and the least common multiple of the number of the magnets of the rotor and the number of teeth of the stator is X, The braking device according to claim 7 , wherein the recesses and the protrusions are disposed on the side surfaces of the teeth at intervals of an angle obtained by dividing 360 degrees by X.

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

11. An electronic device comprising the braking device according to any one of claims 7 to 9 and one or more gears.

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