JP2020078176A - Rotor, motor and brushless wiper motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotor, a motor and a brushless wiper motor capable of suppressing demagnetization of a permanent magnet due to the interlinkage magnetic flux of a stator coil. A rotor 9 includes a rotor core 32, a permanent magnet 33, and a salient pole 35. The salient pole 35 projects radially outward between the permanent magnets 33 adjacent to each other in the circumferential direction on the outer peripheral surface 32b of the rotor core 32. The permanent magnet 33 includes a magnetic coercive portion 39 having a larger intrinsic coercive force than other portions at the peripheral end portion 33s. [Selection diagram] Fig. 3

Description

  The present invention relates to a rotor, a motor and a brushless wiper motor.

  2. Description of the Related Art Conventionally, a surface permanent magnet (SPM) type rotor having permanent magnets for field magnets on the surface of a rotor core has a protrusion protruding radially outward of the rotor core between permanent magnets arranged in the circumferential direction. An inset type rotor is known (for example, refer to Patent Document 1). In this rotor, the rotor core and the protrusions are made of a magnetic material. The protrusion of the rotor core generates a reluctance torque that rotates the rotor core so that the protrusion direction is the direction in which the interlinking magnetic flux due to the coil of the stator easily flows and the magnetic resistance (reluctance) of the magnetic path of the interlinking magnetic flux is reduced. .

International Publication No. 2015/102047

  By the way, in the rotor as described above, the interlinkage magnetic flux due to the coils of the stator easily flows so as to be attracted toward the protrusions of the rotor core, so that the interlinkage magnetic flux penetrates into the magnets at the ends of the permanent magnets. Then, a demagnetizing field may be generated inside the magnet. Therefore, it is desired to suppress demagnetization of the permanent magnet due to the interlinkage magnetic flux of the stator coil.

  Therefore, an object of the present invention is to provide a rotor, a motor, and a brushless wiper motor that can suppress demagnetization of a magnet due to interlinkage magnetic flux of a stator coil.

The present invention adopts the following means in order to solve the above problems.
That is, the rotor of the present invention includes a shaft that rotates about a rotation axis, a rotor core that holds the shaft and that rotates about the rotation axis as a radial center, and a magnet that is arranged on an outer peripheral surface of the rotor core. Salient poles that project outward in the radial direction of the rotor core between the magnets that are adjacent to each other in the circumferential direction of the outer peripheral surface of the rotor core, and the magnet has another portion at both ends in the circumferential direction. It has a coercive force part having a larger intrinsic coercive force.

  According to such a configuration, since both end portions in the circumferential direction of the magnet are provided with the magnetic coercive portions, the intrinsic coercive force is larger than that of other portions such as the central portion in the circumferential direction. As a result, it is possible to suppress demagnetization due to the interlinkage magnetic flux of the stator coil at both circumferential ends of the magnet.

  In addition, in the rotor of the present invention, it is preferable that the coercive force portion is provided in a region including a range where the magnet and the salient pole are in contact with each other when viewed from the magnetization direction of the magnet.

  According to such a configuration, the magnetism and the salient poles of the coercive portion may come into contact with each other at both ends in the circumferential direction in which the thickness in the magnetizing direction may be smaller than that in other portions depending on the magnetizing direction of the magnet. It is provided in the area including the range. As a result, even if both ends in the circumferential direction have low permeance due to the small thickness in the magnetization direction and demagnetization easily occurs, the demagnetization can be suppressed by the magnetic coercive portion. it can.

  Further, in the rotor of the present invention, it is preferable that the coercive force portion is provided in the region including the salient pole at the both end portions when viewed from the magnetization direction.

  According to such a configuration, the coercive force portion is provided at least in a region where the interlinking magnetic flux flowing to the salient poles along the magnetizing direction of the magnet penetrates into the magnet. As a result, it is possible to suppress the generation of a demagnetizing field inside the magnet due to the interlinkage magnetic flux.

  Further, in the rotor of the present invention, the orientation of the magnets is preferably a parallel orientation in which the easy magnetization direction is a direction parallel to the radial direction in the central portion of the magnets.

  According to such a configuration, the coercive force portions are provided at both end portions in the circumferential direction in which the thickness in the magnetization direction is smaller than that in other portions in the parallel orientation. As a result, the permeance is low due to the small thickness in the magnetization direction compared to other portions such as the central portion in the circumferential direction, and demagnetization can be suppressed at both ends in the circumferential direction where demagnetization is likely to occur. it can.

  Further, in the rotor of the present invention, it is preferable that the coercive force portion is provided on the outer peripheral portions of the both end portions.

  With such a configuration, it is possible to suppress the interlinkage magnetic flux due to the coil of the stator from entering the magnet from the outer side in the radial direction of the rotor toward the salient poles by the coercive portion on the outer peripheral portion.

  Further, in the rotor of the present invention, it is preferable that the coercive force portion and the other portion of the magnet are formed of the same material, and the residual magnetic flux density of the other portion is larger than a predetermined residual magnetic flux density.

  With such a configuration, it is possible to secure the stability and strength of the magnetic characteristics of the magnet by increasing the magnetic flux density in the other portions while suppressing the demagnetization by the coercive force portion.

  Further, in the rotor of the present invention, it is preferable that the magnetic coercive portion is formed of a rare earth magnet and the other portion is formed of a ferrite magnet.

  According to such a configuration, it is possible to suppress demagnetization by the coercive force portion and suppress an increase in cost required to secure a magnetic flux density having a desired strength in other portions.

  A motor according to the present invention includes a stator having an annular stator core and a plurality of teeth protruding inward in the radial direction from an inner peripheral surface of the stator core, a coil attached to the teeth, and a plurality of teeth. And the rotor arranged on the inner side in the radial direction.

  According to such a configuration, the motor includes the rotor having the coercive force portions having larger intrinsic coercive force than the other portions at both ends in the circumferential direction of the magnet. As a result, it is possible to suppress the occurrence of demagnetization due to the interlinkage magnetic flux of the coils of the stator at both ends in the circumferential direction of the magnet.

A brushless wiper motor of the present invention includes the above motor.
With such a configuration, it is possible to suppress demagnetization due to the interlinkage magnetic flux of the coils of the stator at both ends in the circumferential direction of the magnet, and to secure a desired output of the brushless wiper motor.

  According to the present invention, it is possible to suppress demagnetization of the magnet due to the interlinkage magnetic flux of the coils of the stator.

It is a perspective view of the wiper motor in the embodiment of the present invention. It is sectional drawing which follows the AA line of FIG. 1 of the wiper motor in embodiment of this invention. FIG. 3 is a plan view of the stator and the rotor in the embodiment of the present invention as viewed from the axial direction. It is a top view which expands and shows a part of rotor in embodiment of this invention, Comprising: It is a figure which shows an example of the lower limit of the arrangement range of the coercive part in a permanent magnet. It is a top view which expands and shows a part of rotor in embodiment of this invention, Comprising: It is a figure which shows an example of the upper limit of the arrangement range of the coercive part in a permanent magnet. It is a top view showing an example of the flow of the magnetic flux to the salient pole of the rotor in the embodiment of the present invention. FIG. 11 is a plan view of a rotor according to a modified example of the embodiment of the present invention as viewed in the axial direction.

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

(Wiper motor)
FIG. 1 is a perspective view of the wiper motor 1. FIG. 2 is a sectional view taken along the line AA of FIG.
As shown in FIGS. 1 and 2, a wiper motor (brushless wiper motor) 1 is, for example, a drive source of a wiper mounted on a vehicle. The wiper motor 1 includes a motor unit (motor) 2, a deceleration unit 3 that decelerates and outputs the rotation of the motor unit 2, and a controller unit 4 that controls driving of the motor unit 2. The motor unit 2 in the embodiment is an example of the motor in the claims.
In the following description, the term “axial direction” refers to the direction of the rotation axis of the shaft 31 of the motor unit 2, the term “circumferential direction” refers to the circumferential direction of the shaft 31, and the term “radial direction” refers to the shaft. 31 in the radial direction.

(Motor part)
The motor unit 2 is provided with a motor case 5, a substantially cylindrical stator 8 housed in the motor case 5, and a rotor 9 provided inside the stator 8 in the radial direction and rotatable with respect to the stator 8. And are equipped with. The motor unit 2 is a so-called brushless motor that does not require a brush when supplying electric power to the stator 8.

(Motor case)
The motor case 5 is made of a material having excellent heat dissipation, such as aluminum die cast. The motor case 5 is composed of a first motor case 6 and a second motor case 7, which are configured to be axially separable. The outer shapes of the first motor case 6 and the second motor case 7 are each formed into a bottomed tubular shape.
The first motor case 6 is integrally formed with the gear case 40 so that the bottom portion 10 is joined to the gear case 40 of the reduction gear unit 3. A through hole 10a into which the shaft 31 of the rotor 9 can be inserted is formed in the center of the bottom portion 10 in the radial direction.

  Further, an outer flange portion 16 that projects outward in the radial direction is formed in the opening portion 6a of the first motor case 6, and an outward flange in the radial direction is formed in the opening portion 7a of the second motor case 7. An outer flange portion 17 is formed so as to project toward. These outer flange portions 16 and 17 are butted against each other to form a motor case 5 having an internal space. A stator 8 is arranged in the internal space of the motor case 5 so as to be fitted inside the first motor case 6 and the second motor case 7.

(Stator)
FIG. 3 is a plan view of the stator 8 and the rotor 9 as seen from the axial direction.
As shown in FIGS. 2 and 3, the stator 8 includes a tubular core portion 21 and a plurality of teeth (for example, six teeth in the present embodiment) protruding inward in the radial direction from the core portion 21. 22 and 22 have an annular stator core 20 integrally formed.
The stator core 20 is formed by stacking a plurality of metal plates in the axial direction. The stator core 20 is not limited to being formed by stacking a plurality of metal plates in the axial direction, and may be formed by press-molding soft magnetic powder, for example.

  The tooth 22 includes a tooth main body 22a and a pair of flange portions 22b that are integrally formed. The tooth main body 22 a projects inward from the inner peripheral surface of the core portion 21 along the radial direction. The collar portion 22b extends in the circumferential direction from the radially inner end of the tooth body 22a. The pair of collar portions 22b are formed so as to extend outward in the circumferential direction from the tooth body 22a. Then, the slots 19 are formed between the flange portions 22b adjacent to each other in the circumferential direction.

  The inner peripheral surface of the core portion 21 and the teeth 22 are covered with an insulator 23 made of resin. A coil 24 is mounted so that it is wound around each tooth 22 from above the insulator 23. Each coil 24 generates a magnetic field for rotating the rotor 9 by the power supply from the controller unit 4.

(Rotor)
The rotor 9 is rotatably provided inside the stator 8 with a minute gap therebetween.
The rotor 9 includes a shaft 31, a rotor core 32, and four permanent magnets 33. Thus, in the motor unit 2, for example, the ratio between the number of magnetic poles of the permanent magnet 33 and the number of slots 19 (teeth 22) is 4: 6.
The rotor 9 rotates with the center line (axis center) C1 of the shaft 31 as a rotation axis, and the rotation axis as a radial center.
The shaft 31 is integrally formed with a worm shaft 44 (see FIG. 2) that constitutes the reduction gear unit 3.
The rotor core 32 is fixed so as to be fitted to 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.

The rotor core 32 is formed by stacking a plurality of metal plates in the axial direction. The rotor core 32 is not limited to the case of being formed by laminating a plurality of metal plates in the axial direction, and may be formed by press-molding soft magnetic powder, for example.
Further, a through hole 32a penetrating in the axial direction is formed substantially in the radial center of the rotor core 32. The shaft 31 is press fitted into the through hole 32a. The shaft 31 may be relatively inserted into the through hole 32a so that the rotor core 32 is fitted to the outside of the shaft 31, and the shaft 31 and the rotor core 32 may be fixed to each other with an adhesive or the like.
In the rotor core 32, the circular arc center of the radially inner inner peripheral surface (that is, the inner peripheral surface of the through hole 32a) and the circular arc center of the radially outer peripheral surface 32b coincide with the position of the axial center C1 of the shaft 31. ..

Further, four salient poles 35 are provided on the outer peripheral surface 32b of the rotor core 32 at equal intervals in the circumferential direction. The salient poles 35 are formed so as to integrally project with the rotor core 32 outward in the radial direction and extend over the entire axial direction of the rotor core 32. The salient pole 35 is formed by stacking a plurality of metal plates in the axial direction similarly to the rotor core 32.
On the outer peripheral surface 32b of the rotor core 32 formed in this way, between the two salient poles 35 that are adjacent in the circumferential direction, each is configured as a magnet housing portion 36.
That is, the rotor 9 is a surface magnet (SPM: Surface Permanent Magnet) type rotor having the field permanent magnet 33 on the outer peripheral surface 32 b of the rotor core 32, and the rotor core 32 is arranged between the permanent magnets 33 arranged in the circumferential direction. This is an inset type rotor provided with a salient pole 35 that projects radially outward.

Further, a concave portion 38 extending in the axial direction is formed on the tip surface 35A of the tip portion 35a of the salient pole 35 (that is, the outer surface in the projecting direction).
Further, round chamfered portions 35b are formed at the corners on both sides in the circumferential direction on the outer side of the salient pole 35 in the projecting direction.
Further, the salient pole 35 is formed such that two side surfaces 35c facing each other in the circumferential direction are parallel to the projecting direction. That is, the salient poles 35 are formed so that the width dimension in the circumferential direction is uniform in the projecting direction.

FIG. 4 is a diagram showing an example of the lower limit of the arrangement range of the magnetic coercive portion 39 in the permanent magnet 33 in the rotor 9. FIG. 5 is a diagram showing an example of the upper limit of the arrangement range of the magnetic coercive portion 39 in the permanent magnet 33 in the rotor 9.
The four permanent magnets 33 are arranged in the four magnet housing portion 36 provided on the outer peripheral surface 32 b of the rotor core 32. Each of the permanent magnets 33 is fixed to the rotor core 32 in the magnet housing portion 36 with, for example, an adhesive.

The permanent magnet 33 is magnetized, for example, so that the orientation of magnetization (magnetic field) becomes parallel orientation along the thickness direction. That is, the orientation of the permanent magnet 33 is a parallel orientation in which the easy magnetization direction is parallel to the radial direction in the central portion of the permanent magnet 33.
The permanent magnets 33 that are adjacent to each other in the circumferential direction are arranged such that their magnetization directions are opposite to each other. The four permanent magnets 33 are arranged so that their magnetic poles alternate in the circumferential direction. That is, the permanent magnet 33 having the N pole on the outer peripheral side and the permanent magnet 33 having the S pole on the outer peripheral side are arranged so as to be adjacent to each other in the circumferential direction. As a result, the salient poles 35 of the rotor core 32 arranged between the permanent magnets 33 adjacent to each other in the circumferential direction are located at the magnetic pole boundaries (pole boundaries).

  In the permanent magnet 33, the circular arc center Ci of the radially inner inner peripheral surface 33b coincides with the position of the axial center C1 of the shaft 31. The arc center Co of the outer peripheral surface 33a on the radially outer side is eccentric with respect to 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 closer to 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, in the permanent magnet 33, the radial thickness at the end portions 33s on both sides in the circumferential direction around the axis C1 of the shaft 31 becomes smaller than the radial thickness at the central portion 33c in the circumferential direction. Along with this, the gap between the outer peripheral surface 33a on the radially outer side of the permanent magnet 33 and the inner peripheral surface of the tooth 22 is the smallest in the central portion 33c in the circumferential direction of the permanent magnet 33, and the central portion 33c in the circumferential direction. Increases with increasing distance from the outer side in the circumferential direction.

  The inner peripheral surface 33b of the permanent magnet 33 contacts almost the entire outer peripheral surface 32b of the rotor core 32. Further, the circumferential side surfaces 33d on both circumferential sides of the permanent magnet 33 are in contact with the side surfaces 35c of the salient poles 35. The circumferential side surface 33d is smoothly connected to the radially inner inner circumferential surface 33b via an arcuate surface 33f.

The permanent magnet 33 includes a coercive force portion 39 having a larger intrinsic coercive force than the other portions at each end portion 33s on both sides in the circumferential direction. The magnetic coercive part 39 is provided, for example, over substantially the entire axial direction of the rotor core 32 in the outer peripheral part 33t of the end part 33s.
The outer shape of the magnetic coercive part 39 is, for example, a curved plate shape provided with an inner peripheral surface 39a and an outer peripheral surface 39b so as to have a predetermined thickness in the radial direction of the permanent magnet 33. The outer peripheral surface 39b of the magnetic coercive part 39 is smoothly connected to the outer peripheral surface 33a of the permanent magnet 33.
In addition, the pair of side surfaces 39c on both sides of the magnetic coercive force portion 39 in the circumferential direction are, for example, flat surfaces. An outer side surface 39c of the magnetic coercive portion 39 in the circumferential direction is connected to a circumferential side surface 33d of the permanent magnet 33.

The outer side surface 39c of the magnetic coercive portion 39 in the circumferential direction is formed so as to gradually approach the central portion 33c of the permanent magnet 33 in the circumferential direction as it goes outward in the projecting direction of the salient poles 35. .. The outer side surface 39c is formed so as to gradually increase in the radial thickness of the permanent magnet 33 as it goes toward the center in the circumferential direction. That is, the permanent magnet 33 is formed such that the distance between the two side surfaces 39c in the circumferential direction gradually decreases as it goes inward in the radial direction.
The pair of side surfaces 39c on both sides in the circumferential direction of the magnetic coercive portion 39 are provided, for example, parallel to the radial direction in the central portion 33c in the circumferential direction of the permanent magnet 33.

The magnetic coercive portion 39 is provided in a region including the salient poles 35 that are in contact with the permanent magnet 33 when viewed from the magnetization direction D of the permanent magnet 33. The coercive force portion 39 is provided in a region including at least a range where the permanent magnet 33 and the salient pole 35 are in contact with each other when viewed from the magnetization direction D of the permanent magnet 33. For example, the magnetic coercive part 39 is configured such that the inner side surface 39c in the circumferential direction of the magnetic coercive part 39 is arranged between the first virtual straight line L1 shown in FIG. 4 and the second virtual straight line L2 shown in FIG. And is provided on the permanent magnet 33.
The first imaginary straight line L1 shown in FIG. 4 is parallel to the magnetization direction D of the permanent magnet 33 and is a region of the side surface 35c of the salient pole 35 that contacts the permanent magnet 33 and that contacts the circumferential side surface 33d of the permanent magnet 33. The inner peripheral edge 35d is included. The second virtual straight line L2 shown in FIG. 5 is parallel to the magnetization direction D of the permanent magnet 33 and includes the inner peripheral end 35e of the side surface 35c of the salient pole 35 that is in contact with the permanent magnet 33.

In the permanent magnet 33, the coercive force portion 39 and the portion other than the coercive force portion 39 are formed of, for example, the same material, and the residual magnetic flux density of the portion other than the coercive force portion 39 is a predetermined residual magnetic flux. It is formed larger than the density.
In addition, in the permanent magnet 33, the magnetic coercive part 39 and the part other than the magnetic coercive part 39 may be formed of different materials, for example. For example, the magnetic coercive part 39 may be formed of a rare earth magnet, and the other parts than the magnetic coercive part 39 may be formed of a ferrite magnet.
Further, the magnetic coercive portion 39 and the portion other than the magnetic coercive portion 39 may be formed of, for example, the same material of the same grade, and only the magnetic coercive portion 39 may be formed of a grain boundary diffusion alloy. The materials of the same grade are materials having the same degree of magnetic force and heat resistance.

(Reduction unit)
1 and 2, the reduction gear unit 3 includes a gear case 40 to which the motor case 5 is attached, and a worm reduction mechanism 41 housed in the gear case 40.
The gear case 40 is formed of a material having excellent heat dissipation, such as aluminum die cast. The outer shape of the gear case 40 is formed in a box shape having an opening 40a on one surface. The gear case 40 has a gear accommodating portion 42 that accommodates the worm reduction mechanism 41 therein. Further, on the side wall 40b of the gear case 40, an opening 43 is formed at a location where the first motor case 6 is integrally formed, through which the through hole 10a of the first motor case 6 and the gear accommodating portion 42 pass. ..

The bottom wall 40c of the gear case 40 is provided with a substantially cylindrical bearing boss 49.
The bearing boss 49 is provided to rotatably support the output shaft 48 of the worm speed reduction mechanism 41, and has a slide bearing (not shown) on its inner peripheral surface.
Further, an O-ring (not shown) is attached to the inner peripheral edge of the tip of the bearing boss 49. This prevents dust and water from entering the inside from the outside through the bearing boss 49.
A plurality of ribs 52 are provided on the outer peripheral surface of the bearing boss 49. This ensures the desired rigidity of the bearing boss 49.

The worm speed reduction mechanism 41 accommodated in the gear accommodating portion 42 includes a worm shaft 44 and a worm wheel 45 meshed with the worm shaft 44.
The worm shaft 44 is arranged coaxially with the shaft 31 of the motor unit 2. Both ends of the worm shaft 44 are rotatably supported by bearings 46 and 47 provided on the gear case 40. The end of the worm shaft 44 on the motor unit 2 side projects to the opening 43 of the gear case 40 via the bearing 46. The projecting end of the worm shaft 44 and the end of the shaft 31 of the motor unit 2 are joined together, and the worm shaft 44 and the shaft 31 are integrated. The worm shaft 44 and the shaft 31 may be integrally formed by molding the worm shaft portion and the rotary shaft portion from one base material.

  The worm wheel 45 meshed with the worm shaft 44 is provided with an output shaft 48 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 projects outside the gear case 40 via the bearing boss 49 of the gear case 40. A spline 48a that can be connected to an electric component (not shown) is formed at the protruding tip of the output shaft 48.

  A sensor magnet (not shown) is provided at the center of the worm wheel 45 in the radial direction on the side opposite to the side where the output shaft 48 is projected. This sensor magnet constitutes one of the rotational position detection units 60 that detect the rotational position of the worm wheel 45. The magnetic detection element 61, which constitutes the other side of the rotational position detection unit 60, is provided in the controller unit 4 which is arranged to face the worm wheel 45 on the sensor magnet side of the worm wheel 45 (the opening 40a side of the gear case 40). There is.

(Controller section)
The controller unit 4 that controls the drive of the motor unit 2 includes a controller board 62 on which the magnetic detection element 61 is mounted, and a cover 63 provided so as to close the opening 40a of the gear case 40. The controller board 62 is arranged so as to face the sensor magnet side of the worm wheel 45 (the opening 40a side of the gear case 40).

The controller board 62 is a so-called epoxy board on which a plurality of conductive patterns (not shown) are formed. The controller board 62 is connected to the terminal portion of the coil 24 pulled out from the stator core 20 of the motor portion 2 and is electrically connected to a terminal (not shown) of the connector 11 provided on the cover 63. Further, on the controller board 62, in addition to the magnetic detection element 61, an FET (Field) for controlling a current supplied to the coil 24 is provided.
A power module (not shown) including a switching element such as an effect transistor (field effect transistor) is mounted. Further, a capacitor (not shown) for smoothing the voltage applied to the controller board 62 is mounted on the controller board 62.

The cover 63 that covers the controller board 62 configured as described above is made of resin. The cover 63 is formed so as to bulge slightly outward. The inner surface side of the cover 63 is a controller housing portion 56 that houses the controller board 62 and the like.
Further, the connector 11 is integrally formed on the outer peripheral portion of the cover 63. The connector 11 is formed so that it can be fitted with a connector extending from an external power source (not shown). The controller board 62 is electrically connected to the terminals (not shown) of the connector 11. As a result, the power of the external power supply is supplied to the controller board 62.

  Further, at the opening edge of the cover 63, a fitting portion 81 that is fitted to the end portion of the side wall 40b of the gear case 40 is formed to project. The fitting portion 81 is composed of two walls 81a and 81b along the opening edge of the cover 63. Then, the end portion of the side wall 40b of the gear case 40 is inserted (fitted) between the two walls 81a and 81b. As a result, the labyrinth portion 83 is formed between the gear case 40 and the cover 63. The labyrinth portion 83 prevents dust or water from entering between the gear case 40 and the cover 63. The gear case 40 and the cover 63 are fixed by fastening bolts (not shown).

(Brushless motor operation)
Next, the operation of the wiper motor 1 will be described.
In the wiper motor 1, the electric power supplied to the controller board 62 via the connector 11 is selectively supplied to each coil 24 of the motor unit 2 via a power module (not shown).
Then, the current flowing through each coil 24 forms a predetermined interlinkage magnetic flux in the stator 8 (teeth 22). This interlinkage magnetic flux generates a magnetic attractive force or repulsive force (magnet torque) with the effective magnetic flux formed by the permanent magnet 33 of the rotor 9.
In addition, the salient poles 35 of the rotor core 32 have the protruding direction in a direction in which the interlinking magnetic flux from the stator 8 (teeth 22) easily flows, and reduce the magnetic resistance (reluctance) of the magnetic path of the interlinking magnetic flux. Reluctance torque that rotates the rotor core 32 is generated.
These magnet torque and reluctance torque continuously rotate the rotor 9.
The rotation of the rotor 9 is transmitted to a worm shaft 44 that is integrated with the shaft 31, and is further transmitted to a worm wheel 45 that is meshed 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 a desired electric component.

  The detection signal of the rotation position of the worm wheel 45 detected by the magnetic detection element 61 mounted on the controller board 62 is output to an external device (not shown). The external device (not shown) is, for example, a software function unit that functions when a processor such as a CPU (Central Processing Unit) executes a predetermined program. The software function unit is an ECU (Electronic Control Unit) including a processor such as a CPU, a ROM (Read Only Memory) for storing programs, a RAM (Random Access Memory) for temporarily storing data, and an electronic circuit such as a timer. . Further, at least a part of the external device (not shown) may be an integrated circuit such as an LSI (Large Scale Integration). An external device (not shown) controls the switching timing of the switching elements and the like of the power module (not shown) based on the rotation position detection signal of the worm wheel 45 to control the drive of the motor unit 2. The output of the drive signal of the power module and the drive control of the motor unit 2 may be executed by the controller unit 4 instead of an external device (not shown).

As described above, according to the rotor 9 of the present embodiment, the circumferential end portions 33 s of the permanent magnet 33 are provided with the magnetic coercive portions 39, so that the permanent magnet 33 has a magnetic coercive portion 39. Large intrinsic coercive force. As a result, it is possible to suppress the occurrence of demagnetization due to the interlinkage magnetic flux of the coil 24 of the stator 8 at both circumferential ends 33s of the permanent magnet 33.
FIG. 6 is a plan view showing an example of the flow of magnetic flux to the salient poles 35 of the rotor 9.
As shown in FIG. 6, when the interlinking magnetic flux of the coil 24 flows from the teeth 22 on the front side in the rotation direction R toward the salient poles 35 during the rotation of the rotor 9, along the magnetization direction D of the permanent magnet 33. Interlinkage magnetic flux may enter inside. However, the magnetic coercive portion 39 provided on the outer peripheral portion 33t of the end portion 33s in the circumferential direction of the permanent magnet 33 suppresses the interlinking magnetic flux from entering the inside along the magnetization direction D of the permanent magnet 33, and It is recognized that the demagnetizing field is suppressed from being generated inside the magnet 33.

In addition, the coercive force portion 39 includes a range in which the permanent magnet 33 and the salient pole 35 are in contact with each other in both circumferential end portions 33s of the parallel-oriented permanent magnet 33 having a smaller thickness in the magnetization direction than other portions. It is provided in the area. As a result, even if both ends 33s in the circumferential direction have a low permeance due to a small thickness in the magnetization direction and demagnetization is likely to occur, the demagnetization is suppressed by the magnetic coercive section 39. be able to.
Further, the coercive force portion 39 is provided in a region where the interlinking magnetic flux flowing to the salient poles 35 along the magnetization direction of the permanent magnet 33 penetrates into the permanent magnet 33. As a result, it is possible to suppress the generation of the demagnetizing field inside the permanent magnet 33 due to the interlinkage magnetic flux.

Further, in the permanent magnet 33, the coercive force portion 39 and the portion other than the coercive force portion 39 are formed of the same material, and the residual magnetic flux density of the portion other than the coercive force portion 39 is a predetermined residual magnetic flux. It is formed larger than the density. Thereby, while suppressing the demagnetization by the magnetic coercive part 39, by increasing the magnetic flux density in other parts, it is possible to secure the stability and strength of the magnetic characteristics of the permanent magnet 33.
Further, in the permanent magnet 33, when the coercive force portion 39 and other portions other than the coercive force portion 39 are made of different materials, the coercive force portion 39 is made of a rare earth magnet and the coercive force portion is formed. Other parts than 39 may be formed by a ferrite magnet. Thereby, while suppressing demagnetization by the magnetic coercive part 39, it is possible to suppress an increase in cost required to secure a magnetic flux density having a desired strength in other parts.
Further, in the permanent magnet 33, when the coercive force portion 39 and other portions other than the coercive force portion 39 are made of the same material of the same grade, only the coercive force portion 39 is formed by the grain boundary diffusion alloy. May be. As a result, the magnetic force and heat resistance of the coercive force portion 39 can be increased more than other portions.

  Further, according to the wiper motor 1 of the present embodiment, the rotor 9 is provided with the coercive force portion 39 having a larger coercive force than the other portions at both circumferential end portions 33s of the permanent magnet 33. As a result, demagnetization due to the interlinkage magnetic flux of the coil 24 of the stator 8 can be suppressed at both circumferential ends 33s of the permanent magnet 33, and a desired output can be secured.

(Modification)
Hereinafter, modified examples of the embodiment will be described.
In the above-described embodiment, the permanent magnet 33 is provided with the magnetic coercive portion 39 on the outer peripheral portion 33t of the end 33s, but the present invention is not limited to this, and the magnetic coercive portion 39 is provided over the entire area of the end 33s. Good.
FIG. 7 is a plan view of the rotor according to the modified example of the embodiment of the present invention as viewed from the axial direction.
As shown in FIG. 7, in the rotor 9 of the modified example, the coercive force portion 39 is provided in the entire area including at least the area where the permanent magnet 33 and the salient pole 35 are in contact with each other when viewed from the magnetization direction D of the permanent magnet 33. Has been. For example, the magnetic coercive part 39 is provided in a region including the salient poles 35 that are in contact with the permanent magnet 33 when viewed from the magnetization direction D of the permanent magnet 33. That is, the magnetic coercive portion 39 is provided between the second virtual straight line L2 and the circumferential end of the permanent magnet 33. In this case, the circumferential side surfaces 33d on both sides in the circumferential direction of the permanent magnet 33, which come into contact with the side surface 35c of the salient pole 35, and a part of the arc surface 33f that smoothly connects the circumferential side surface 33d and the inner circumferential surface 33b, It is formed by the surface of the magnetic coercive portion 39.

In the embodiment described above, the orientation of the permanent magnet 33 is the parallel orientation in which the easy magnetization direction is parallel to the radial direction in the central portion of the permanent magnet 33, but the orientation is not limited to this. The orientation of the permanent magnet 33 may be a radial orientation in which the easy magnetization direction is parallel to the radial direction of the permanent magnet 33.
In this case, the easy magnetization direction near the ends 33s on both sides in the circumferential direction of the permanent magnet 33 adjacent to the salient pole 35 is substantially parallel to the protruding direction of the salient pole 35. As a result, when the rotor 9 rotates, for example, from the tooth 22 on the front side in the rotation direction R toward the salient pole 35, the circumferential end 33s of the permanent magnet 33 is moved from the direction intersecting the protruding direction of the salient pole 35. It is possible to prevent the interlinking magnetic flux from penetrating into the permanent magnet 33 and to prevent the demagnetizing field from being generated inside the permanent magnet 33 by making it traverse.

Although the arc center Co of the outer peripheral surface 33a is eccentric with respect to the axis C1 of the shaft 31 in the above-described embodiment, the present invention is not limited to this.
For example, in the permanent magnet 33, the arc center Co of the radially outer peripheral surface 33a may coincide with the axis C1 of the shaft 31. In this case, in the permanent magnet 33, the radial thickness between the outer peripheral surface 33a and the inner peripheral surface 33b is uniform over the entire circumferential direction. Along with this, the gap between the outer peripheral surface 33a on the radially outer side of the permanent magnet 33 and the inner peripheral surface of the tooth 22 becomes constant over the entire circumferential direction.

  In the above-described embodiment, the concave portion 38 is formed in the distal end surface 35A of the distal end portion 35a of the salient pole 35, but the concave portion 38 is not limited to this and the concave portion 38 may be omitted.

  In the above-described embodiment, the wiper motor 1 is taken as an example of the motor, but the motor according to the present invention is not limited to the wiper motor 1. For example, the motor may be a drive source of various electric components mounted on the vehicle (for example, a power window, a sunroof, an electric seat, etc.) or a drive source mounted on various devices other than the vehicle.

  The embodiments of the present invention are presented as examples, and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. The embodiments and their modifications are included in the scope of the invention and the scope thereof, and are included in the invention described in the claims and the scope of equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Wiper motor (brushless wiper motor), 2 ... Motor part (motor), 8 ... Stator, 9 ... Rotor, 20 ... Stator core, 21 ... Core part, 22 ... Teeth, 24 ... Coil, 31 ... Shaft, 32 ... Rotor core , 32b ... Outer peripheral surface, 33 ... Permanent magnet (magnet), 33a ... Outer peripheral surface, 33c ... Circumferential center part, 33s ... Circumferential end part, 33t ... Outer peripheral part, 35 ... Salient pole, 35a ... Tip part, 35A ... Tip surface, 39 ... Magnetic coercive part

Claims (9)

A shaft that rotates around the axis of rotation,
While holding the shaft, a rotor core that rotates about the rotation axis as a radial center,
A magnet arranged on the outer peripheral surface of the rotor core,
Salient poles that project outward in the radial direction of the rotor core between the magnets that are adjacent in the circumferential direction of the outer peripheral surface of the rotor core;
Equipped with
The magnet is provided with a coercive force portion having a larger intrinsic coercive force than other portions at both end portions in the circumferential direction,
A rotor characterized in that The magnetic coercive portion is provided in a region including a range in which the magnet and the salient pole are in contact with each other when viewed from the magnetization direction of the magnet at the both ends.
The rotor according to claim 1, wherein the rotor is a rotor. The coercive portion is provided in a region including the salient poles when viewed from the magnetization direction at the both end portions,
The rotor according to claim 2, wherein: The orientation of the magnet is a parallel orientation in which the easy magnetization direction is parallel to the radial direction in the central portion of the magnet,
The rotor according to any one of claims 1 to 3, wherein the rotor is a rotor. The magnetic coercive portion is provided on the outer peripheral portions of the both end portions,
The rotor according to claim 1, wherein the rotor is a rotor. The coercive part and the other part of the magnet are formed of the same material,
The residual magnetic flux density of the other portion is larger than a predetermined residual magnetic flux density,
The rotor according to any one of claims 1 to 5, wherein: The coercive portion is formed of a rare earth magnet,
The other portion is formed by a ferrite magnet,
The rotor according to any one of claims 1 to 5, wherein: A stator having an annular stator core and a plurality of teeth protruding inward in the radial direction from the inner peripheral surface of the stator core;
A coil attached to the tooth,
The rotor according to any one of claims 1 to 7, which is arranged inside the radial direction with respect to the plurality of teeth,
With
A motor characterized by that. The motor according to claim 8 is provided,
A brushless wiper motor characterized in that

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