JP2020078177A - Rotor, motor and brushless wiper motor - Google Patents

Abstract

To provide a rotor, a motor and a brushless wiper motor, capable of properly holding a permanent magnet on a rotor surface and also capable of suppressing an increase in leakage magnetic flux.SOLUTION: A rotor 9 includes a rotor core 32, a permanent magnet 33, a salient pole 35 and a claw 37. The permanent magnet 33 includes a flat surface 33g formed on the outside in the radial direction at least in part in the axial direction of an edge in the circumferential direction. The salient pole 35 projects outward in the radial direction between the permanent magnets 33 adjacent to each other on the outer peripheral surface 32b of the rotor core 32 in the circumferential direction. The claw 37 projects toward the flat surface 33g of the permanent magnet 33 at least in part in the axial direction of a tip 35a of the salient pole 35. The claw 37 includes a contact surface 37a in surface contact with the flat surface 33g, the contact surface being in parallel with the flat surface 33g closer on a center side than an edge 33j of the permanent magnet 33 in the axial direction.SELECTED DRAWING: Figure 4

Description

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

  Conventionally, as a surface permanent magnet (SPM) type rotor having a permanent magnet for a field on the surface of a rotor core, an inset type rotor provided with a magnet holding member made of a magnetic material between permanent magnets arranged in a circumferential direction. A rotor is known (for example, refer to Patent Document 1). The magnet holding member of the rotor includes a protrusion that protrudes outward in the radial direction of the rotor core, and a pair of claws provided at the tip of the protrusion. The claw portion comes into contact with an outer arc surface of the permanent magnet that bulges in an arc shape, exposes a part of the magnetic pole surface of the permanent magnet to the outside, and restricts the movement of the permanent magnet.

JP, 2009-261191, A

By the way, in the rotor described above, the pair of claw portions provided on the protrusion are deformed so as to come into contact with the outer arc surface of the permanent magnet by being spread by caulking or the like. Therefore, the tip of the claw portion may locally contact the outer arc surface of the permanent magnet, and if local stress concentration occurs in the permanent magnet, the permanent magnet may be damaged.
Further, in the rotor as described above, the magnetic characteristics and the output characteristics may deteriorate due to an increase in the magnetic flux leaking from the end of the permanent magnet to the magnet holding member. Therefore, it is desired to suppress an increase in leakage flux from the permanent magnet to the magnet holding member.

  Therefore, an object of the present invention is to provide a rotor, a motor, and a brushless wiper motor that can appropriately hold a permanent magnet on the surface of the rotor and can suppress an increase in leakage flux.

The present invention adopts the following means in order to solve the above problems.
That is, the rotor of the present invention, a shaft that rotates around a rotation axis, a rotor core that holds the shaft and that rotates around the rotation axis as a radial center, and a permanent magnet that is arranged on the outer peripheral surface of the rotor core. A flat surface formed on the outer side in the radial direction of the rotor core in at least a part in the axial direction parallel to the rotation axis among the end portions in the circumferential direction of the permanent magnet, and the circumferential direction of the outer peripheral surface of the rotor core. And a salient pole protruding outward in the radial direction between the adjacent permanent magnets, and at least a part of the tip of the salient pole in the axial direction faces the flat surface of the permanent magnet. And a claw portion protruding from the permanent magnet. The claw portion includes a contact surface that is parallel to the flat surface and is in surface contact with the flat surface on the center side of the axial end of the permanent magnet.

According to such a configuration, the claw portions of the salient poles of the rotor core fix the permanent magnet to the outer peripheral surface of the rotor core by making surface contact with the flat surface of the permanent magnet. As a result, it is possible to suppress the local stress from concentrating on the surface of the permanent magnet and prevent the permanent magnet from being damaged, while properly holding the permanent magnet.
Further, the claw portion of the salient pole is in surface contact with the flat surface on the center side of the end portion of the permanent magnet in the axial direction. As a result, for example, the permanent magnet can be appropriately fixed while avoiding the end portion that is more likely to be damaged by the action of stress than the central portion of the permanent magnet in the axial direction, and the permanent magnet can be fixed at the axial end portion of the permanent magnet. It is possible to suppress the magnetic flux of the magnet from leaking to the salient poles through the claws, and to suppress the deterioration of the magnetic characteristics and the output characteristics.

  In the rotor of the present invention, it is preferable that both ends of the permanent magnet in the axial direction project outward in the axial direction from both ends of the rotor core in the axial direction.

  According to such a configuration, it is possible to suppress the leakage magnetic flux from both ends of the permanent magnet in the axial direction to the rotor core.

  In the rotor of the present invention, it is preferable that a concave portion extending in the axial direction is formed on the outer surface of the salient pole in the protruding direction.

  With such a configuration, the radial distance between the surface of the salient pole on the outer side in the protruding direction and the stator arranged on the outer side in the radial direction of the rotor becomes uneven. As a result, it is possible to suppress an abrupt change in the magnetic flux density generated in the stator due to the salient poles, and to suppress an abrupt torque fluctuation and an increase in torque ripple of the rotor core.

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

  According to such a configuration, the permanent magnets are oriented in parallel, and the easy magnetization direction near the circumferential ends of the permanent magnets adjacent to the salient poles intersects the salient poles. As a result, for example, compared with the case where the easy magnetization direction near the circumferential end of the permanent magnet is substantially parallel to the protruding direction of the salient pole, the magnetic path is formed by the magnetic flux leaking from the permanent magnet to the salient pole through the claw portion. Is suppressed, and an increase in leakage flux can be suppressed.

  In the rotor of the present invention, the magnetic susceptibility of the claw portion is preferably smaller than the magnetic susceptibility of the salient pole.

  According to such a configuration, the claw portion is less likely to be magnetized than the salient pole because the magnetic susceptibility of the claw portion is smaller than that of the salient pole. As a result, it is possible to suppress the formation of a magnetic path due to the magnetic flux leaking from the permanent magnet adjacent to the salient pole to the salient pole via the claw portion, and to suppress the increase of the leakage magnetic flux.

  In the rotor of the present invention, it is preferable that the claw portion is in surface contact with the flat surface of the permanent magnet in a compressed and deformed state.

  According to this structure, the claw portion has a magnetic susceptibility smaller than that of the salient pole that is not compressed and deformed by the action of the compressive stress. As a result, it is possible to suppress the formation of a magnetic path due to the magnetic flux leaking from the permanent magnet adjacent to the salient pole to the salient pole via the claw portion, and to suppress the increase of the leakage magnetic flux.

  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 that appropriately holds the permanent magnet on the surface of the rotor and suppresses the increase of the leakage magnetic flux. As a result, the desired output can be secured while preventing damage to the permanent magnet.

A brushless wiper motor of the present invention includes the above motor.
With such a configuration, it is possible to prevent the permanent magnet in the rotor from being damaged while ensuring a desired output of the brushless wiper motor.

  According to the present invention, it is possible to properly hold the permanent magnet on the surface of the rotor and suppress an increase in leakage flux.

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 perspective view of the rotor in the embodiment of the present invention. It is a graph which shows an example of the magnetizing force ratio with respect to the stress of the magnetic material which concerns on embodiment of this invention. It is a figure explaining the method of forming a pair of nail | claw part of a compression deformation state in the salient pole of the rotor core in embodiment of this invention. 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. It is a perspective view of the rotor in the 1st modification of the embodiment of the present invention. In the first modified example of the embodiment of the present invention, an example of the relationship between the ratio of the outer diameter portion of the permanent magnet held by the claw portion of the salient pole (outer diameter retention rate) and the effective magnetic flux of the permanent magnet It is a graph figure which shows. A graph showing an example of the relationship between the cogging torque and the ratio of the portion held by the claw portion of the salient pole to the outer diameter portion of the permanent magnet in the first modified example of the embodiment of the present invention. It is a figure.

  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 from the core portion 21 in the radial direction. 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 project outward in the radial direction and extend over the entire axial direction of the rotor core 32.
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.
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.

FIG. 4 is a perspective view of the rotor 9.
A pair of claws 37 projecting outward on both sides in the circumferential direction is formed on at least a portion of the outer end portion 35a of the salient pole 35 in the projecting direction in the axial direction of the rotor core 32. For example, the pair of claw portions 37 are provided over the entire axial direction of the rotor core 32 at the tip end portion 35 a of the salient pole 35. As will be described later, the pair of claw portions 37 project toward the flat surfaces 33g of the two permanent magnets 33 that sandwich the salient pole 35 from both sides in the circumferential direction, and are in surface contact with the flat surfaces 33g. For example, each claw portion 37 includes a contact surface 37a, which is parallel to the flat surface 33g of the permanent magnet 33 and is in surface contact with the flat surface 33g, in the radial direction.
Further, a concave portion 38 extending in the axial direction is formed on the tip end surface 35A of the tip end portion 35a provided with the pair of claw portions 37 in the salient pole 35 (that is, the outer surface in the protruding direction). As a result, the radially outer surfaces of the pair of claw portions 37 are connected via the surface of the recess 38. As will be described later, the concave portion 38 is formed by compressive deformation of the pair of claw portions 37. That is, the pair of claw portions 37 are formed so as to be in a relatively high compression deformation state as compared with the salient pole 35.

FIG. 5 is a graph showing an example of the magnetizing force ratio α with respect to the stress of the magnetic material. The stress in FIG. 5 is, for example, the first compressive stress S1, the second compressive stress S2 larger than the first compressive stress S1, and the tensile stress S3.
The magnetizing force is the strength of the magnetic field required for the desired magnetization of the magnetic material. The magnetizing force ratio α is the ratio of the magnetizing force when the stress of the magnetic material is other than zero due to the tensile stress or the compressive stress to the magnetizing force when the stress of the magnetic material is zero. For example, when the magnetization force ratio α is smaller than 1, the magnetic material is likely to be magnetized due to the stress, and when the magnetization force ratio α is larger than 1, the magnetic material is less likely to be magnetized due to the stress. Is becoming
As shown in FIG. 5, when the magnetic field strength B is less than the predetermined strength Ba, the magnetic material is easily magnetized due to the tensile stress and hard to be magnetized due to the compressive stress. ..
As a result, the pair of claw portions 37 that are in a relatively higher compression deformation state than the salient poles 35 are less likely to be magnetized than the salient poles 35, and the magnetic susceptibility of the pair of claw portions 37 is It is smaller than the magnetic susceptibility of the salient pole 35.

Returning to FIGS. 3 and 4, 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, for example, a ferrite magnet, a neodymium bond magnet, a neodymium sintered magnet, or the like.

The permanent magnet 33 is magnetized, for example, so that the orientation of magnetization (magnetic field) is a radial radial orientation along the radial direction. That is, the orientation of the permanent magnet 33 is a radial orientation in which the easy magnetization direction is parallel to the radial direction 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. Each surface on both sides in the circumferential direction of the permanent magnet 33 is provided with a circumferential side surface 33d that contacts the salient pole 35 and a connecting surface 33e that is connected to the circumferential side surface 33d.
The circumferential side surface 33d is smoothly connected to the radially inner inner circumferential surface 33b via an arcuate surface 33f.
The connection surface 33e is provided radially outward of the circumferential side surface 33d, and is further connected to the outer peripheral surface 33a through a radially outer flat surface 33g.

The connection surface 33e is formed as a flat surface, for example. The connecting surface 33e is formed so as to gradually approach the central portion 33c in the circumferential direction of the permanent magnet 33 as it goes outward in the protruding direction of the salient pole 35. The connection surface 33e is formed, for example, so as to gradually change the radial thickness of the permanent magnet 33 in an increasing tendency as it goes outward in the radial direction. That is, the pair of connection surfaces 33e on both sides of the permanent magnet 33 in the circumferential direction are formed so as to gradually change the circumferential spacing to decrease with the outward radial direction.
Further, the connection surface 33e is provided, for example, in parallel with the radial direction in the central portion 33c of the permanent magnet 33 in the circumferential direction.

  The flat surface 33g is connected to the outer peripheral surface 33a and the connecting surface 33e at the circumferential end 33s on the outer side in the radial direction of the permanent magnet 33. The flat surface 33g is provided, for example, in parallel with the direction orthogonal to the protruding direction of the salient pole 35. The flat surface 33g is parallel to the contact surface 37a provided on the radially inner side of the claw portion 37 projecting outward from the salient pole 35 in the circumferential direction, and is in surface contact with the contact surface 37a.

The thickness of the permanent magnet 33 in the axial direction is larger than the thickness of the rotor core 32 in the axial direction. For example, both axial ends of the permanent magnet 33 project (overhang) outward in the axial direction more than both axial ends of the rotor core 32.
Further, an inclined surface 33k connected to the axial end surface 33h and the outer peripheral surface 33a is formed at a corner portion on the radially outer side of the axial end portion 33j of the permanent magnet 33. The inclined surface 33k is formed so that the radial thickness of the permanent magnet 33 gradually becomes smaller toward the axial end surface 33h. The inclined surface 33k is formed, for example, as a flat surface that inclines at a predetermined angle with respect to the axis.

  The flat surface 33g of the permanent magnet 33 is provided, for example, at least in a part closer to the center than the axial end portion 33j so as to avoid a portion where the inclined surface 33k of the axial end portion 33j is formed. May be For example, the flat surface 33g is provided over the entire salient pole 35 of the rotor core 32 in the axial direction. As a result, the flat surface 33g of the permanent magnet 33 is in contact with the claw portion 37 of the salient pole 35 of the rotor core 32 on the center side of the end portion 33j in the axial direction of the permanent magnet 33.

(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).

(Method for manufacturing wiper motor)
Next, among the methods for manufacturing the wiper motor 1, particularly, a method for forming the pair of claw portions 37 in a compression deformed state on the salient poles 35 of the rotor core 32 in the method for manufacturing the rotor 9 will be described.
FIG. 6 is a diagram illustrating a method of forming the pair of claw portions 37 in the compression deformation state on the salient poles 35 of the rotor core 32.
First, the rotor member 91 including the rotor core 32 and the four salient poles 35 is formed by, for example, stacking a plurality of metal plates or press-molding soft magnetic powder. The rotor member 91 includes a pair of protrusions 92 that protrude outward on both sides in the circumferential direction at the tip end portions 35 a of the salient poles 35.
Next, jigs 93 that sandwich each salient pole 35 from both sides in the circumferential direction are installed on the rotor member 91. The outer shape of the jig 93 is, for example, substantially the same as the outer shape of the end 33s of the permanent magnet 33 in the circumferential direction.

Next, the molding member 94 is pressed from the outer side to the inner side in the projecting direction of each salient pole 35 against the tip end portion 35 a of each salient pole 35 to form the recess 38, thereby forming the recess 38. The pair of protrusions 92 is compressed and deformed inward in the radial direction together with 35a. As a result, the claw portion 37 in a compressed and deformed state having the contact surface 37a parallel to the direction orthogonal to the protruding direction of the salient pole 35 in the radial direction is formed. The outer shape of the molding member 94 is formed, for example, in a rod shape in which the cross section of the tip portion is tapered in a V shape or a U shape.
Next, the jig 93 is removed from the rotor core 32, the permanent magnet 33 is attached to the rotor core 32, and is fixed to the rotor core 32 with, for example, an adhesive agent.

(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 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 ECU (Electronic Control Unit) including electronic circuits 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), etc. The external device (not shown) is based on a rotation position detection signal of the worm wheel 45. The switching timing of the switching elements and the like of the power module (not shown) is controlled 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 are performed in place of an external device (not shown). It may be executed by the controller unit 4.

As described above, according to the rotor 9 of the present embodiment, the claw portions 37 of the salient poles 35 of the rotor core 32 are brought into surface contact with the flat surface 33g of the permanent magnet 33, thereby causing the permanent magnet 33 to move to the outer peripheral surface 32b of the rotor core 32. Fixed to. As a result, it is possible to suppress the local stress from concentrating on the surface of the permanent magnet 33, prevent the permanent magnet 33 from being damaged, and appropriately hold the permanent magnet 33.
Further, since the claw portion 37 is provided over the entire axial direction of the rotor core 32, the claw portion 37 is locally provided on the surface of the permanent magnet 33 as compared with the case where it is provided only in a part of the rotor core 32 in the axial direction. Concentration of stress can be suppressed.
In addition to this, by making both axial ends of the permanent magnet 33 project outward (overhanging) in the axial direction more than both axial ends of the rotor core 32, the axial ends of the permanent magnet 33 extend from the axial ends of the rotor core 32. It is possible to suppress magnetic flux leaking to both ends in the axial direction.

Further, since the claw portion 37 is in surface contact with the flat surface 33g of the permanent magnet 33 in a relatively high compression deformation state as compared with the salient pole 35, it is hard to be magnetized as compared with the salient pole 35. The magnetic susceptibility of the claw portion 37 is smaller than that of the salient pole 35. As a result, it is possible to suppress the formation of a magnetic path due to the magnetic flux leaking to the salient pole 35 from the permanent magnet 33 adjacent to the salient pole 35 via the claw portion 37, and to suppress the increase of the leakage magnetic flux.
FIG. 7 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. 7, the orientation of the permanent magnet 33 is a radial orientation in which the easy magnetization direction is radial along the radial direction of the permanent magnet 33, and the end portions 33 s on both sides in the circumferential direction of the permanent magnet 33 and the salient poles 35 are arranged. A magnetic path due to the leakage magnetic flux is easily formed between them. However, the claws 37 are less likely to be magnetized than the salient poles 35, and the magnetic path due to the leakage flux is generated between the salient poles 35 and the ends 33s on both sides in the circumferential direction of the permanent magnet 33 via the claws 37. It is observed that the formation is suppressed. As a result, it is possible to suppress an increase in leakage magnetic flux and suppress deterioration in magnetic characteristics and output characteristics.

  Further, the claw portion 37 of the salient pole 35 is in surface contact with the flat surface 33g on the center side of the axial end 33j of the permanent magnet 33. Accordingly, for example, the permanent magnet 33 can be appropriately fixed while avoiding the end portion 33j that is more likely to be damaged by the action of stress as compared with the axial center side of the permanent magnet 33, and the permanent magnet 33 can be axially fixed. It is possible to prevent the magnetic flux of the permanent magnet 33 from leaking to the salient pole 35 through the claw portion 37 at the end portion 33j, and to suppress the deterioration of the magnetic characteristics and the output characteristics.

  Further, a concave portion 38 extending over the entire axial direction is formed on the tip end surface 35A of the salient pole 35 on the outer side in the projecting direction. As a result, the radial distance between the tip end surface 35A of the salient pole 35 and the tooth 22 of the stator 8 (particularly, the flange portion 22b) becomes uneven. As a result, abrupt changes in the magnetic flux density generated in the teeth 22 (particularly, the flange portions 22b) before and after the salient poles 35 pass between the teeth 22 while the rotor 9 is rotating are suppressed, and abrupt torque fluctuations in the rotor 9 and It is possible to suppress an increase in torque ripple.

  Further, according to the wiper motor 1 of the present embodiment, the permanent magnet 33 is appropriately held on the outer peripheral surface 32b of the rotor core 32, and the rotor 9 in which the increase of the leakage magnetic flux is suppressed is provided. As a result, the desired output can be secured while preventing the permanent magnet 33 from being damaged.

(Modification)
Hereinafter, modified examples of the embodiment will be described.
In the above-described embodiment, the pair of claw portions 37 is provided over the entire axial direction of the rotor core 32 at the tip end portion 35a of the salient pole 35, but the present invention is not limited to this. The pair of claw portions 37 may be provided only on a part of the tip portion 35 a of the salient pole 35 in the axial direction of the rotor core 32.
FIG. 8 is a perspective view of the rotor 9 in the first modified example of the embodiment.
The rotor 9 of the first modified example includes a pair of claw portions 37 at both ends in the axial direction of the rotor core 32 at the tip end portion 35 a of the salient pole 35. A concave portion 38 is formed in a portion of the tip surface 35A of the tip portion 35a of the salient pole 35 where the pair of claw portions 37 is provided.
According to the first modified example, as compared with the case where the pair of claw portions 37 are provided over the entire axial direction of the rotor core 32 as in the above-described embodiment, a desired fixing stability with respect to the permanent magnet 33 is secured. However, it is possible to increase the effective magnetic flux and suppress the increase in cogging torque and torque ripple due to the distortion of the magnetic field.

FIG. 9 shows the relationship between the ratio of the portion of the outer diameter of the permanent magnet 33 held by the claw portion 37 of the salient pole 35 (outer diameter holding ratio) and the effective magnetic flux of the permanent magnet 33 in the first modification. It is a graph figure which shows an example. FIG. 10 is a graph showing an example of the relationship between the outer diameter retention rate of the permanent magnet 33 and the cogging torque in the first modified example.
As shown in FIG. 9, as the outer diameter retention rate increases, the magnetic flux leaking from the permanent magnet 33 to the salient poles 35 via the claws 37 changes to increase, so that the effective magnetic flux of the permanent magnet 33 decreases. Changes to. Further, as shown in FIG. 10, as the outer diameter retention rate increases, the magnetic flux leaking from the permanent magnet 33 to the salient pole 35 via the claw portion 37 and the distortion of the induced voltage waveform change to an increasing tendency, so that the magnetic field The cogging torque and the torque ripple caused by the distortion of the above change in an increasing tendency. With these, by providing the claw portions 37 only in a part of the rotor core 32 in the axial direction, the outer diameter retention rate is reduced, so that the effective magnetic flux of the permanent magnet 33 is increased and the cogging torque and the torque ripple are reduced. You can

In the above embodiment, the orientation of the permanent magnet 33 is the radial orientation in which the easy magnetization direction is parallel to the radial direction of the permanent magnet 33, but the orientation is not limited to this. The orientation of the permanent magnet 33 may be parallel orientation in which the easy magnetization direction is parallel to the radial direction in the central portion of the permanent magnet 33.
In this case, the easy magnetization direction near the end portions 33s on both sides in the circumferential direction of the permanent magnet 33 adjacent to the salient pole 35 intersects the protruding direction of the salient pole 35. As a result, the formation of a magnetic path due to the magnetic flux leaking from the permanent magnet 33 to the salient pole 35 via the claw portion 37 is suppressed, and an increase in the leakage magnetic flux can be suppressed.

In the above-described embodiment, the concave portion 38 is formed on the distal end surface 35A of the distal end portion 35a of the salient pole 35 provided with the pair of claw portions 37, but the concave portion 38 is not limited to this and the concave portion 38 is omitted. May be done.
In this case, in the method for manufacturing the wiper motor 1 according to the above-described embodiment, when forming the pair of claw portions 37 in the compression deformed state on the salient poles 35 of the rotor core 32, for example, the molding member 94 having a flat surface at the tip end portion thereof. May be used to compressively deform the pair of protrusions 92 inward in the radial direction.
In addition, in the above-described embodiment, when the rotor 9 is formed by stacking a plurality of metal plates, the metal plate formed by press punching or the like is pre-compressed in a portion corresponding to the claw portion 37. Therefore, the magnetic susceptibility may be relatively reduced.
Further, in the above-described embodiment, when the pair of protrusions 92 of the rotor member 91 is compressed and deformed by the molding member 94, the jig 93 is previously attached to the rotor member 91, but the present invention is not limited to this. A permanent magnet 33 may be attached instead of 93.

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 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, 33a ... Outer peripheral surface, 33c ... Circumferential center portion, 33d ... Circumferential side surface, 33e ... Connection surface, 33g ... Flat surface, 33j ... Axial end portion, 33s ... Circumferential end portion, 35 ... Salient pole, 35a ... Tip portion, 35A ... Tip surface, 37 ... Claw portion, 37a ... Contact surface, 38 ... Recessed portion

Claims (8)

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 permanent magnet arranged on the outer peripheral surface of the rotor core;
A flat surface formed on the outer side in the radial direction of the rotor core in at least a part in the axial direction parallel to the rotation axis among the end portions in the circumferential direction of the permanent magnet;
Salient poles protruding outward in the radial direction between the permanent magnets adjacent to each other in the circumferential direction of the outer peripheral surface of the rotor core;
A claw portion projecting toward the flat surface of the permanent magnet in at least a part of the tip portion of the salient pole in the axial direction,
Equipped with
The claw portion includes a contact surface that is parallel to the flat surface and is in surface contact with the flat surface on the center side of the end portion of the permanent magnet in the axial direction,
A rotor characterized in that Both ends of the permanent magnet in the axial direction project outward in the axial direction from both ends of the rotor core in the axial direction.
The rotor according to claim 1, wherein the rotor is a rotor. A recess extending in the axial direction is formed on the outer surface of the salient pole in the protruding direction,
The rotor according to claim 1, wherein the rotor is a rotor. The orientation of the permanent magnet is a parallel orientation in which the easy magnetization direction is a direction parallel to the radial direction in the central portion of the permanent magnet,
The rotor according to any one of claims 1 to 3, wherein the rotor is a rotor. The magnetic susceptibility of the claw portion is smaller than the magnetic susceptibility of the salient pole,
The rotor according to claim 1, wherein the rotor is a rotor. The claw portion is in surface contact with the flat surface of the permanent magnet in a compressed deformation state,
The rotor according to claim 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 6, 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 7,
A brushless wiper motor characterized in that

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