Rotor, motor and brushless motor

Abstract

The present invention provides a rotor, a motor and a brushless motor that can ensure the fixation stability of permanent magnets and suppress the increase of magnetic field strain. The rotor includes a rotor core, a permanent magnet, and a protrusion. The protrusion protrudes radially outward between the adjacent permanent magnets in the circumferential direction on the outer peripheral surface of the rotor core. The orientation of the permanent magnet is a parallel orientation in which the easy magnetization direction becomes a direction parallel to the radial direction of the central part of the permanent magnet. The circumferential side surface of the permanent magnet contacts the protrusion in the circumferential direction. The connecting surface of the permanent magnet is connected to the circumferential side surface and the radial outer peripheral surface. The position of the front end of the protrusion in the protruding direction is arranged in the range between the central part of the circumferential side surface in the protruding direction and the intersecting ridge part of the circumferential side surface and the connecting surface.

Description

Technical Field

[0001] The invention relates to a rotor, a motor and a brushless motor. Background Art

[0002] As a surface magnet (SPM) type rotor including field permanent magnets on the surface of a rotor core, an embedded type rotor is known, which includes protrusions protruding radially outward of the rotor core between permanent magnets arranged in the circumferential direction (for example, see Patent Document 1). In this rotor, the protrusions of the rotor core restrict the movement of the permanent magnets on the surface of the rotor core in the rotational direction.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2015 / 102047 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In addition, in the rotor as described above, as the radial protrusion length of the protrusion increases, the fixing stability of the permanent magnet tends to increase. However, as the radial protrusion length of the protrusion containing the magnetic material increases, the strain of the magnetic field tends to increase. Therefore, there is a risk that the cogging torque and torque ripple increase due to the strain of the magnetic field, and the noise and vibration of the motor increase.

[0008] Therefore, an object of the present invention is to provide a rotor, a motor, and a brushless motor that can ensure the fixing stability of the magnets on the rotor surface and suppress the increase of the magnetic field strain.

[0009] Technical means of solving problems

[0010] The present invention adopts the following means to solve the above-mentioned problems.

[0011] That is, the rotor of the present invention includes: an axis rotating around a rotation axis; a rotor core holding the axis and rotating with the rotation axis as a radial center; a magnet arranged on the outer peripheral surface of the rotor core; and a protrusion protruding outward in the radial direction between the magnets adjacent in the circumferential direction of the outer peripheral surface of the rotor core; and the orientation of the magnet is parallel to the direction parallel to the radial direction of the central part of the magnet, and the magnet includes: a circumferential side surface in contact with the protrusion in the circumferential direction; and a connecting surface connected to the circumferential side surface and the radial outer peripheral surface, and formed in a manner that gradually approaches the circumferential center of the magnet as it moves toward the outer side of the protrusion direction; the position of the front end of the protrusion in the protrusion direction is formed in a manner that is arranged in the range between the central part of the circumferential side surface in the protrusion direction and the intersecting ridgeline part of the circumferential side surface and the connecting surface.

[0012] According to this structure, the protrusion can support more than half of the circumferential side surface of the magnet in the protruding direction. Thus, the required fixing stability (for example, rideability, etc.) of the magnet on the outer peripheral surface of the rotor core can be ensured.

[0013] In addition, the protrusion is formed in a manner that does not protrude outwardly beyond the intersecting ridgeline of the circumferential side surface of the magnet and the connecting surface in the protruding direction. Thus, the magnetic flux leaking from the magnet to the protrusion and the strain of the induced voltage waveform can be suppressed to below a prescribed allowable level as much as possible, and the effective magnetic flux of the permanent magnet can be maintained within a prescribed range including a maximum value.

[0014] In addition, the magnets are oriented in parallel, and the easy magnetization direction near the circumferential end of the magnet adjacent to the protrusion intersects with the protrusion direction of the protrusion. This can suppress the formation of a magnetic path by the magnetic flux leaking from the magnet to the protrusion, thereby suppressing the increase of leakage magnetic flux.

[0015] Furthermore, in the rotor of the present invention, it is preferable that the connection surface is parallel to the easy magnetization direction of the magnet.

[0016] According to this structure, the connection surface is parallel to the easy magnetization direction of the magnets in parallel orientation, thereby suppressing the distortion of the induced voltage waveform.

[0017] Furthermore, in the rotor of the present invention, it is preferable that the thickness of the magnet in the radial direction is formed to be greater than the thickness of the rotor core in the radial direction.

[0018] According to this structure, even in the case where the magnet is formed to have a relatively larger radial thickness than the rotor core, the required fixing stability of the magnet can be ensured by the protrusion.

[0019] The motor of the present invention comprises: a stator including an annular stator core and a plurality of teeth protruding from the inner circumference of the stator core toward the inner side in the radial direction; a coil mounted on the teeth; and the rotor arranged on the inner side in the radial direction relative to the plurality of teeth.

[0020] According to this structure, the motor includes a rotor that can ensure the required effective magnetic flux of the magnet, and the magnetic flux leaking from the magnet to the protrusion and the strain of the induced voltage waveform are suppressed. As a result, the increase in cogging torque and torque ripple caused by the strain of the magnetic field can be suppressed, the increase in vibration and noise when the motor is driven can be suppressed, and the required output can be ensured.

[0021] The brushless motor of the present invention includes the motor.

[0022] According to this configuration, it is possible to ensure the required output of the brushless motor and suppress increases in vibration and noise during driving.

[0023] Effects of the Invention

[0024] According to the present invention, it is possible to ensure the fixing stability of the magnet in the rotor and suppress the increase of the magnetic field strain. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a perspective view of a brushless motor in accordance with an embodiment of the present invention.

[0026] Figure 2 The brushless motor in the embodiment of the present invention is along Figure 1 Cross-sectional view of line AA.

[0027] Figure 3 This is a plan view of the stator and the rotor according to the embodiment of the present invention as viewed from the axial direction.

[0028] Figure 4 This is a plan view showing a part of the rotor in the embodiment of the present invention in an enlarged manner, and is a view showing the dimensions of the rotor core and the permanent magnets.

[0029] Figure 5 This is a plan view showing a part of the rotor in the embodiment of the present invention in an enlarged manner, and is a view showing the length range of the protrusion in the protruding direction.

[0030] Figure 6 This is a graph showing an example of the relationship between the length of the protrusion of the rotor and the effective magnetic flux of the permanent magnet in the embodiment of the present invention.

[0031] Figure 7 This is a graph showing an example of the relationship between the length of the protrusion of the rotor and the strain rate of the induced voltage in the embodiment of the present invention.

[0032] Figure 8 This is a plan view showing an example of the flow of magnetic flux to the protrusions of the rotor in the embodiment of the present invention.

[0033] Fig. 9 It is a plan view showing an example of the flow of magnetic flux to the protrusions of the rotor in a comparative example of the embodiment of the present invention.

[0034] [Explanation of Symbols]

[0035] 1: Brushless motor

[0036] 2: Motor part (motor)

[0037] 8: Stator

[0038] 9: Rotor

[0039] 20: stator core

[0040] 21: Core

[0041] 22: Teeth

[0042] 24: Coil

[0043] 31: Axis

[0044] 32: Rotor core

[0045] 32b: Outer surface

[0046] 33: Permanent magnet (magnet)

[0047] 33a: Outer surface

[0048] 33c: Central

[0049] 33d: circumferential side

[0050] 33e: Connection surface

[0051] 33g: Central

[0052] 33h: Cross ridges

[0053] 35: Protrusion

[0054] 35t: Front end DETAILED DESCRIPTION

[0055] Hereinafter, a rotor, a motor, and a brushless motor according to embodiments of the present invention will be described with reference to the drawings.

[0056] (Brushless Motor)

[0057] Figure 1 It is a perspective view of the brushless motor 1 . Figure 2 It is along Figure 1 Cross-sectional view of line AA.

[0058] like Figure 1 and Figure 2 As shown, the brushless motor 1 is, for example, a driving source of a sunroof mounted on a vehicle. The brushless motor 1 includes a motor unit (motor) 2, a speed reduction unit 3 that reduces the speed of the motor unit 2 and outputs the speed, and a controller unit 4 that controls the driving of the motor unit 2. The motor unit 2 in the embodiment is an example of a motor in the scope of the claims.

[0059] In the following description, only the axial direction refers to the rotation axis direction of the shaft 31 of the motor unit 2 , only the circumferential direction refers to the circumferential direction of the shaft 31 , and only the radial direction refers to the radial direction of the shaft 31 .

[0060] (Electrical Department)

[0061] The motor unit 2 includes a motor housing 5, a substantially square cylindrical stator 8 housed in the motor housing 5, and a rotor 9 disposed radially inward of the stator 8 and rotatable relative to the stator 8. The motor unit 2 is a so-called brushless motor that does not require brushes when supplying power to the stator 8.

[0062] (Motor housing)

[0063] The motor case 5 is made of a material having excellent heat dissipation properties such as die-cast aluminum. The motor case 5 includes a first motor case 6 and a second motor case 7 that are divisible in the axial direction. The first motor case 6 and the second motor case 7 are each formed in a bottomed cylindrical shape.

[0064] The first motor case 6 is formed in a bottomed square tube shape, for example. The second motor case 7 is formed in a bottomed tube shape, for example, with a substantially rounded regular hexagonal cross section. The outer peripheral surface of the second motor case 7 includes six corner portions 7A and a flat portion 7B.

[0065] The first motor case 6 is integrally formed with the gear box 40 of the speed reducing unit 3 so that the end portion 10 is joined to the gear box 40. A through hole 10a is formed substantially at the radial center of the end portion 10, through which the shaft 31 of the rotor 9 can be inserted.

[0066] In addition, an edge portion 16 for joining the second motor housing 7 is formed at the opening portion 6a of the first motor housing 6, and an outer flange portion 17 extending radially outward is formed at the opening portion 7a of the second motor housing 7. The edge portion 16 and the outer flange portion 17 are butted against each other to form the motor housing 5 having an internal space. In addition, the stator 8 is arranged in the internal space of the motor housing 5 so that a part of the coil 24 described below is accommodated inside the first motor housing 6, and the stator core 20 described below is fitted inside the second motor housing 7.

[0067] (stator)

[0068] Figure 3 It is a plan view of the stator 8 and the rotor 9 as viewed from the axial direction.

[0069] like Figure 2 , Figure 3 As shown, the stator 8 includes a stator core 20 formed by integrally forming a cylindrical core portion 21 and a plurality of (for example, six in this embodiment) teeth 22 protruding radially inward from the core portion 21 .

[0070] The stator core 20 is formed by laminating a plurality of metal plates in the axial direction. The stator core 20 is not limited to being formed by laminating a plurality of metal plates in the axial direction, and may be formed by, for example, press-forming soft magnetic powder.

[0071] The core 21 is formed into a square tube with a substantially rounded regular hexagonal cross section to fit inside the second motor housing 7. Thus, the outer peripheral surface of the core 21 includes six corners and a flat portion. A plurality of teeth 22 protrude radially inward from the portions of the cross section of the core 21 corresponding to the sides of the regular hexagon.

[0072] The tooth 22 includes an integrally formed tooth body 22a and a pair of flange portions 22b. The tooth body 22a protrudes radially inward from the inner circumferential surface of the core portion 21. The flange portion 22b extends circumferentially from the radial inner end of the tooth body 22a. The pair of flange portions 22b are formed in a manner extending from the tooth body 22a to the outer side in the circumferential direction. A slit 19 is formed between adjacent flange portions 22b in the circumferential direction.

[0073] The inner peripheral surface of the core 21 and the teeth 22 are covered with a resin insulator 23. Coils 24 are mounted so as to be wound around the surfaces of the insulator 23 and the teeth 22. Each coil 24 generates a magnetic field for rotating the rotor 9 when supplied with power from the controller 4.

[0074] (Rotor)

[0075] The rotor 9 is rotatably disposed radially inside the stator 8 via a small gap. The rotor 9 includes a shaft 31, a rotor core 32, and four permanent magnets 33. As described above, in the motor unit 2, for example, the ratio of the number of magnetic poles of the permanent magnets 33 to the number of slits 19 (teeth 22) is 4:6.

[0076] The rotor 9 uses the center line (axial center) C1 of the shaft 31 as a rotation axis and rotates with the rotation axis as a radial center.

[0077] The shaft 31 and the worm shaft 44 (see Figure 2 The shaft 31 rotates around the rotation axis.

[0078] The rotor core 32 is fixed so as to be fitted on the outside of the shaft 31. The outer shape of the rotor core 32 is formed in a cylindrical shape with the shaft 31 as the axis C1.

[0079] The rotor core 32 is formed by laminating a plurality of metal plates in the axial direction. The rotor core 32 is not limited to being formed by laminating a plurality of metal plates in the axial direction, and may be formed by, for example, press-forming soft magnetic powder.

[0080] In addition, a through hole 32a is formed in the radial direction substantially at the center of the rotor core 32. The shaft 31 is pressed into the through hole 32a. Furthermore, the shaft 31 can be relatively inserted into the through hole 32a in a manner that the rotor core 32 is embedded on the outside of the shaft 31, and the shaft 31 and the rotor core 32 are fixed by using an adhesive or the like.

[0081] In the rotor core 32 , the arc center of the radially inner inner peripheral surface (ie, the inner peripheral surface of the through hole 32 a ) and the arc center of the radially outer outer peripheral surface 32 b coincide with the axis C1 of the shaft 31 .

[0082] Furthermore, four protrusions 35 are provided at equal intervals in the circumferential direction on the outer peripheral surface 32 b of the rotor core 32 . The protrusions 35 are formed so as to protrude radially outward and extend along the entire axial direction of the rotor core 32 .

[0083] The protrusion 35 is formed so that two side surfaces 35a facing each other in the circumferential direction are parallel to the protruding direction. That is, the protrusion 35 is formed so that the width dimension in the circumferential direction is uniform in the protruding direction.

[0084] Furthermore, rounded chamfered portions 35 b are formed at corners on both sides in the circumferential direction on the outer side of the protruding direction of the protrusion 35 .

[0085] On the outer peripheral surface 32 b of the rotor core 32 formed in the above manner, a magnet housing portion 36 is formed between each of two protrusions 35 adjacent to each other in the circumferential direction.

[0086] That is, the rotor 9 is a surface magnet (SPM) type rotor including permanent magnets 33 for excitation on the outer peripheral surface 32b of the rotor core 32, and is an embedded type rotor including protrusions 35 protruding radially outward of the rotor core 32 between the permanent magnets 33 arranged along the circumferential direction.

[0087] The four permanent magnets 33 are arranged in four magnet housing portions 36 provided on the outer peripheral surface 32b of the rotor core 32. Each permanent magnet 33 is fixed to the rotor core 32 in the magnet housing portion 36 by, for example, an adhesive or the like.

[0088] The permanent magnet 33 is, for example, a ferrite magnet, a neodymium bond magnet, or a neodymium sintered magnet.

[0089] The permanent magnet 33 is magnetized so that the magnetization (magnetic field) is oriented parallel to the thickness direction. That is, the permanent magnet 33 is oriented parallel to the radial direction of the central portion of the permanent magnet 33.

[0090] Furthermore, the permanent magnets 33 adjacent to each other in the circumferential direction are arranged so that their magnetization directions are opposite to each other. The four permanent magnets 33 are arranged so that their magnetic poles are different from each other in the circumferential direction. That is, the permanent magnets 33 with the N poles on the outer circumferential side and the permanent magnets 33 with the S poles on the outer circumferential side are arranged adjacent to each other in the circumferential direction. Thus, the protrusions 35 of the rotor core 32 arranged between the permanent magnets 33 adjacent to each other in the circumferential direction are located at the boundaries of the magnetic poles (pole boundaries).

[0091] Figure 4 It is a plan view showing a part of the rotor 9 in an enlarged manner, and is a view showing the dimensions of the rotor core 32 and the permanent magnet 33 .

[0092] In the permanent magnet 33 , the arc center Ci of the inner peripheral surface 33 b on the radial inner side coincides with the position of the axis C1 of the shaft 31 .

[0093] In the permanent magnet 33, the arc center Co of the radially outer peripheral surface 33a is offset toward the axis C1 of the shaft 31. Specifically, the arc center Co of the outer peripheral surface 33a of the permanent magnet 33 is set in a manner that is more offset toward the outer peripheral surface 32b of the rotor core 32 than the axis C1 in the radial direction passing through the center of the permanent magnet 33. As a result, the permanent magnet 33 is formed in a manner that the radial thickness of the end portions 33s on both sides of the circumferential direction around the axis C1 of the shaft 31 is smaller than the radial thickness of the central portion 33c in the circumferential direction. Accordingly, the gap between the radially outer peripheral surface 33a of the permanent magnet 33 and the inner peripheral surface of the tooth 22 is the smallest at the central portion 33c in the circumferential direction of the permanent magnet 33, and changes to increase as it moves away from the central portion 33c in the circumferential direction in the circumferential direction.

[0094] The radial thickness of the permanent magnet 33 is formed to be greater than the radial thickness of the rotor core 32. For example, the radial thickness Rm of the circumferential center portion 33c of the permanent magnet 33 is formed to be greater than the radial thickness Rc of the circumferential center portion 32c of the rotor core 32.

[0095] The substantially entire inner peripheral surface 33b of the permanent magnet 33 is in contact with the outer peripheral surface 32b of the rotor core 32. In addition, each surface on both sides of the permanent magnet 33 in the circumferential direction includes a circumferential side surface 33d in contact with the protrusion 35, and a connecting surface 33e connecting the circumferential side surface 33d and the radially outer outer peripheral surface 33a.

[0096] The circumferential side surface 33d is smoothly connected to the inner circumferential surface 33b on the radial inner side via the arc surface 33f. The circumferential side surface 33d is formed as a flat surface, for example.

[0097] The connecting surface 33e is provided at a position radially outward of the circumferential side surface 33d, and is connected to the circumferential side surface 33d and the outer peripheral surface 33a.

[0098] The connection surface 33e is formed, for example, as a flat surface. The connection surface 33e is formed so as to gradually approach the central portion 33c of the circumferential direction of the permanent magnet 33 as it approaches the outer side of the protrusion direction of the protrusion 35. The connection surface 33e is formed, for example, so as to gradually increase the radial thickness of the permanent magnet 33 as it approaches the outer side in the radial direction. That is, the pair of connection surfaces 33e on both sides of the circumferential direction of the permanent magnet 33 are formed so as to gradually decrease the circumferential spacing as it approaches the outer side in the radial direction.

[0099] In addition, the connection surface 33 e is provided in parallel with the easy magnetization direction of the permanent magnet 33 .

[0100] Figure 5 It is a plan view showing a part of the rotor 9 in an enlarged manner, and is a view showing the length range of the protrusion 35 in the protruding direction.

[0101] The position of the front end 35t of the protrusion 35 in the protruding direction is arranged within the range between the central portion 33g of the circumferential side surface 33d of the permanent magnet 33 in the protruding direction and the intersecting ridge portion 33h of the circumferential side surface 33d and the connecting surface 33e. That is, the position of the front end 35t is arranged between the straight line L1 connecting the central portions 33g of the circumferential side surfaces 33d of the two permanent magnets 33 adjacent to each other so as to sandwich the protrusion 35 from both sides in the circumferential direction and connecting the intersecting ridge portions 33h of the two permanent magnets 33 adjacent to each other.

[0102] For example, with the axis C1 of the shaft 31 as the center, the radius R (outer diameter / 2) of the circle connected to the front end 35t of the protrusion 35 is greater than the radius (first radius) R1 of the circle connected to the straight line L1, and is less than the radius (second radius) R2 of the circle connected to the straight line L2.

[0103] Figure 6 : is a graph showing an example of the relationship between the length of the protrusion 35 of the rotor 9 and the effective magnetic flux of the permanent magnet 33 . Figure 7 3 is a graph showing an example of the relationship between the length of the protrusion 35 of the rotor 9 and the strain rate of the waveform of the induced voltage. Figure 6 and Figure 7 In FIG. 5 , the length of the protrusion 35 is, for example, the radius R (outer diameter / 2) of a circle in contact with the front end 35 t of the protrusion 35 .

[0104] In the rotor 9, as the length of the protrusion 35 in the protruding direction increases, the fixing stability of the permanent magnet 33 in contact with the protrusion 35 (for example, the riding performance with respect to the magnet housing 36, etc.) tends to increase. On the other hand, as the length of the protrusion 35 in the protruding direction increases, the magnetic flux leaking from the permanent magnet 33 to the protrusion 35 and the strain of the induced voltage waveform tend to increase.

[0105] The induced voltage is a voltage induced in each coil 24 by external driving of the rotor 9 when the coils 24 of the stator 8 are not energized from the power supply. The distortion of the induced voltage waveform is generated, for example, by superimposing harmonics on the sinusoidal induced voltage waveform, and causes an increase in vibration and noise when the brushless motor 1 is driven. Figure 7 The strain rate shown is zero when the induced voltage waveform is sinusoidal.

[0106] like Figure 6 and Figure 7 As shown, as the radius R corresponding to the front end 35t of the protrusion 35 increases from the first radius R1, the strain of the induced voltage waveform changes to increase. In contrast, the effective magnetic flux of the permanent magnet 33 to the tooth 22 becomes maximum at the second radius R2.

[0107] That is, the lower limit of the range for specifying the length of the protrusion 35 in the protruding direction is set, for example, in such a manner that the required fixing stability is ensured by supporting at least more than half of the circumferential side surface 33d of the permanent magnet 33 in the protruding direction by the protrusion 35. In addition, the upper limit of the range for specifying the length of the protrusion 35 in the protruding direction is set, for example, in such a manner that the strain of the induced voltage waveform is suppressed to a prescribed allowable level or less as much as possible and the effective magnetic flux of the permanent magnet 33 is maintained within a prescribed range including the maximum value Wm.

[0108] (Speed ​​Reduction Unit)

[0109] Back to Figure 1 and Figure 2 The speed reduction unit 3 includes: a gear box 40 , on which the motor housing 5 is installed; and a worm speed reduction mechanism 41 , which is accommodated in the gear box 40 .

[0110] The gear box 40 is formed of a material having excellent heat dissipation properties, such as die-cast aluminum. The outer shape of the gear box 40 is formed, for example, in a box shape. The gear box 40 includes a gear receiving portion 42 that receives the worm gear reduction mechanism 41. In addition, in the end portion 40a of the gear box 40, an opening portion 43 is formed at a portion where the first motor housing 6 is integrally formed so that the through hole 10a of the first motor housing 6 and the gear receiving portion 42 pass therethrough.

[0111] Furthermore, a guide plate 49 is provided in the gear box 40. The guide plate 49 is provided to rotatably support the output shaft 48 of the worm reduction mechanism 41.

[0112] The worm reduction mechanism 41 accommodated in the gear accommodation portion 42 includes a worm shaft 44 and a worm wheel 45 meshing with the worm shaft 44 .

[0113] The worm shaft 44 is coaxially arranged with the shaft 31 of the motor part 2. In addition, both ends of the worm shaft 44 are supported in a freely rotatable manner by bearings 46 and 47 provided in the gear box 40. The end of the worm shaft 44 on the motor part 2 side protrudes to the opening 43 of the gear box 40 via the bearing 46. The protruding end of the worm shaft 44 is joined to the end of the shaft 31 of the motor part 2, so that the worm shaft 44 and the shaft 31 are integrated. Furthermore, the worm shaft 44 and the shaft 31 can also be formed integrally by molding the worm shaft portion and the rotating shaft portion from a single base material.

[0114] In the worm wheel 45 meshing with the worm shaft 44, an output shaft 48 is provided at the radial center of the worm wheel 45. The output shaft 48 is arranged coaxially with the rotation axis direction of the worm wheel 45, and is connected to a gear unit 50 protruding to the outside of the gear box 40 via a guide plate 49 of the gear box 40. The gear unit 50 is connected to an electrical device not shown.

[0115] Furthermore, the worm shaft 44 is provided with a rotation position detection unit 60 for detecting the rotation position of the worm shaft 44. The rotation position detection unit 60 is connected to the controller unit 4.

[0116] (Controller part)

[0117] The controller unit 4 that controls the driving of the motor unit 2 includes a controller substrate 62 on which a magnetic detection element and the like are mounted. The controller substrate 62 is disposed in the through hole 10 a of the first motor case 6 .

[0118] The controller substrate 62 is a substrate formed by forming a plurality of conductive patterns (not shown) on a so-called epoxy substrate. The end of the coil 24 pulled out from the stator core 20 of the motor unit 2 is connected to the controller substrate 62, and the terminal 11 provided on the gear box 40 is electrically connected. In addition, in addition to the magnetic detection element, a power module (not shown) is installed on the controller substrate 62, and the power module includes a switching element such as a field effect transistor (FET) that controls the current supplied to the coil 24. Furthermore, a capacitor (not shown) and the like are installed on the controller substrate 62 to smooth the voltage applied to the controller substrate 62.

[0119] The terminal 11 is formed so as to be engageable with a connector extending from an external power source (not shown). The terminal 11 is electrically connected to the controller substrate 62. Thus, the power of the external power source is supplied to the controller substrate 62.

[0120] (Brushless motor operation)

[0121] Next, the operation of the brushless motor 1 will be described.

[0122] In the brushless motor 1 , the electric power supplied to the controller substrate 62 via the terminal 11 is selectively supplied to each coil 24 of the motor unit 2 via a power module (not shown).

[0123] Thus, the current flowing through each coil 24 forms a predetermined interlinkage magnetic flux in the stator 8 (teeth 22 ), and the interlinkage magnetic flux and the effective magnetic flux formed by the permanent magnets 33 of the rotor 9 generate magnetic attraction or repulsion (magnetic torque).

[0124] The protrusions 35 of the rotor core 32 generate reluctance torque to rotate the rotor core 32 so that the protrusion direction becomes a direction in which the interlinkage flux from the stator 8 (teeth 22) easily flows and the reluctance of the magnetic path of the interlinkage flux is reduced.

[0125] These magnetic torques and reluctance torques cause the rotor 9 to continue rotating.

[0126] The rotation of the rotor 9 is transmitted to the worm shaft 44 integrated with the shaft 31, and further transmitted to the worm wheel 45 meshing with the worm shaft 44. The rotation of the worm wheel 45 is transmitted to the output shaft 48 connected to the worm wheel 45, and the output shaft 48 drives the necessary electrical equipment.

[0127] In addition, the detection signal of the rotation position of the worm wheel 45 detected by the magnetic detection element and the rotation position detection unit 60 installed on the controller substrate 62 is output to an external machine not shown in the figure. The external machine not shown in the figure is, for example, a software function unit, which functions by executing a predetermined program by a processor such as a central processing unit (CPU). The software function unit is an electronic control unit (ECU) including an electronic circuit such as a processor such as a CPU, a read-only memory (ROM) for storing programs, a random access memory (RAM) for temporarily storing data, and a counter. In addition, at least a part of the external machine not shown in the figure can be an integrated circuit such as a large-scale integrated circuit (LSI). The external machine not shown in the figure controls the switching timing of the switch element of the power module not shown in the figure based on the rotation position detection signal of the worm wheel 45, and controls the drive of the motor unit 2. Furthermore, the output of the drive signal of the power module and the drive control of the motor unit 2 can also be performed by the controller unit 4 instead of the external machine not shown in the figure.

[0128] As described above, according to the rotor 9 of this embodiment, the protrusion 35 of the rotor core 32 can support more than half of the circumferential side surface 33d of the permanent magnet 33 in the protruding direction. As a result, the required fixing stability (for example, rideability, etc.) of the permanent magnet 33 on the outer peripheral surface 32b of the rotor core 32 can be ensured.

[0129] For example, even when the radial thickness of the permanent magnet 33 is formed to be relatively larger than the radial thickness of the rotor core 32 , the protrusion 35 can ensure the required fixing stability of the permanent magnet 33 .

[0130] In addition, the protrusion 35 is formed in a manner that does not protrude outward in the protruding direction beyond the intersecting ridgeline 33h of the circumferential side surface 33d and the connecting surface 33e of the permanent magnet 33. Thus, the magnetic flux leaking from the permanent magnet 33 to the protrusion 35 and the strain of the induced voltage waveform can be suppressed to a predetermined allowable level or less, and the effective magnetic flux of the permanent magnet 33 can be maintained within a predetermined range including a maximum value.

[0131] Furthermore, the orientation of the permanent magnets 33 is parallel, and the easy magnetization directions near the ends 33s on both sides of the permanent magnets 33 adjacent to the protrusions 35 intersect with the protruding direction of the protrusions 35. Thus, the magnetic flux leaking from the permanent magnets 33 to the protrusions 35 can be suppressed from forming a magnetic path, thereby suppressing the increase of the leakage magnetic flux.

[0132] Figure 8This is a plan view showing an example of the flow of magnetic flux to the protrusion 35 of the rotor 9 in the embodiment. Fig. 9 It is a plan view showing an example of the flow of magnetic flux to the protrusion 35 of the rotor 9 in a comparative example of the embodiment.

[0133] exist Fig. 9 In the comparative example shown, the orientation of the permanent magnet 33 is a radial orientation in which the easy magnetization direction D is radially radiated along the radial direction of the permanent magnet 33. In addition, the position of the front end 35t of the protrusion 35 in the protruding direction is arranged at a position further outside than the intersecting ridgeline portion 33h of the permanent magnet 33. This makes it easy to form a magnetic path between the end portions 33s on both sides of the circumferential direction of the permanent magnet 33 and the protrusion 35 by the magnetic flux leaking from the permanent magnet 33 to the protrusion 35.

[0134] On the other hand, Figure 8 In the embodiment shown, the orientation of the permanent magnet 33 is parallel. In addition, the position of the front end 35t of the protrusion 35 in the protruding direction is arranged within the range between the central part 33g and the intersecting ridge part 33h of the circumferential side surface 33d of the permanent magnet 33. By this, the formation of the magnetic path using the magnetic flux leaking from the permanent magnet 33 to the protrusion 35 is suppressed compared with the comparative example.

[0135] In addition, the connection surface 33e of the permanent magnet 33 is parallel to the easy magnetization direction of the permanent magnet 33, which is parallel oriented. This can suppress the distortion of the induced voltage waveform.

[0136] In addition, according to the brushless motor 1 of the present embodiment, the rotor 9 is provided, which can ensure the required effective magnetic flux of the permanent magnet 33 and suppress the magnetic flux leaking from the permanent magnet 33 to the protrusion 35 and the strain of the induced voltage waveform. As a result, the increase of the cogging torque and the torque ripple caused by the strain of the magnetic field can be suppressed, and the increase of the vibration and noise when the brushless motor 1 is driven can be suppressed, and the required output can be ensured.

[0137] (Variation Example)

[0138] Hereinafter, modified examples of the embodiment will be described.

[0139] In the above embodiment, the arc center Co of the radially outer peripheral surface 33a of the permanent magnet 33 is offset from the axis C1 of the shaft 31, but the present invention is not limited thereto. The arc center Co of the outer peripheral surface 33a of the permanent magnet 33 may also coincide with the position of the axis C1 of the shaft 31, similarly to the arc center Ci of the radially inner peripheral surface 33b.

[0140] Furthermore, in the above-described embodiment, the brushless motor 1 is a driving source for a sunroof mounted on a vehicle, but the present invention is not limited thereto. For example, the brushless motor 1 may be a driving source for various electrical devices mounted on a vehicle (e.g., electric windows, electric seats, and wipers) or a driving source for various devices mounted outside the vehicle.

[0141] The embodiments of the present invention are presented as examples and are not intended to limit the scope of the invention. These embodiments may be implemented in various other forms and may be omitted, replaced, or modified in various ways without departing from the gist of the invention. These embodiments or their modifications are included in the invention described in the claims and their equivalents as long as they are included in the scope or gist of the invention.

Claims

1. A rotor, characterized in that: include: Axle, which rotates about an axis of rotation; a rotor core that holds the shaft and rotates with the rotation axis as a radial center; A magnet is disposed on the outer peripheral surface of the rotor core; and a protrusion protruding outward in the radial direction between the magnets adjacent to each other in the circumferential direction of the outer peripheral surface of the rotor core, wherein two opposing surfaces of the protrusion are parallel to each other; and The magnet is oriented such that the easy magnetization direction is parallel to the radial direction of the central portion of the magnet. The magnet comprises: A circumferential side surface having a flat surface in contact with an opposite surface of the protrusion in the circumferential direction; and a connecting surface connected to the circumferential side surface and the radially outer outer circumferential surface, and formed in a manner that gradually approaches the circumferential center of the magnet as it moves toward the outer side of the protrusion direction, and the connecting surface is parallel to the easy magnetization direction of the magnet; The flat surface of the circumferential side surface of the magnet is parallel to the flat surface of the adjacent magnet. The position of the front end of the protrusion in the protruding direction is formed so as to be arranged in a range between a central portion of the circumferential side surface in the protruding direction and an intersecting ridge portion of the circumferential side surface and the connecting surface.

2. The rotor according to claim 1, characterized in that: The radial thickness of the magnet is formed to be greater than the radial thickness of the rotor core.

3. A motor, characterized in that: include: A stator including an annular stator core and a plurality of teeth protruding from an inner circumference of the stator core toward the inner side in the radial direction; a coil mounted on the tooth; and The rotor according to claim 1 or 2, arranged on the inner side in the radial direction relative to the plurality of teeth.

4. A brushless motor, characterized in that: Comprising the motor as claimed in claim 3.

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