JP7462533B2 - Rotor, motor and brushless wiper motor - Google Patents

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 magnet on the surface of the rotor core, an inset type rotor with protrusions protruding radially outward from the rotor core between the permanent magnets arranged in the circumferential direction has been known. In this rotor, the rotor core and the protrusions are formed from a magnetic material. The protrusions of the rotor core protrude in the direction that makes it easy for the interlinkage magnetic flux of the stator coil to flow, and generate a reluctance torque that rotates the rotor core so as to reduce the magnetic resistance (reluctance) of the magnetic path of the interlinkage magnetic flux.

However, in such a rotor, the flux linkage of the stator coils tends to flow toward the protrusions of the rotor core, and this can enter the interior of the permanent magnet at both circumferential ends of the magnet, generating a demagnetizing field inside the magnet. For this reason, it is desirable to suppress the demagnetization of the permanent magnets caused by the flux linkage of the stator coils. Various techniques have been disclosed for suppressing the demagnetization of the permanent magnets.
For example, a technique has been disclosed in which a magnetically coercive portion having a larger intrinsic coercivity than other portions is provided at both circumferential ends of a permanent magnet (see, for example, Patent Document 1).

JP 2020-78176 A

However, in reality, if one were to provide the above-mentioned holding portions at both circumferential ends of the permanent magnet, it would be necessary to change the material of the holding portions from that of other portions. As a result, the permanent magnet would be difficult to manufacture, and manufacturing costs could increase.

The present invention provides a rotor, motor, and brushless wiper motor that can be easily manufactured, while suppressing increases in manufacturing costs, and that can suppress demagnetization of magnets due to interlinkage magnetic flux of the stator coil.

In order to solve the above problems, a rotor according to the present invention includes a shaft that rotates about a rotation axis, a rotor core that holds the shaft and rotates about the rotation axis in a radial direction, a plurality of magnets arranged side by side along a circumferential direction on an outer circumferential surface of the rotor core, and salient poles that protrude radially outwardly of the rotor core between adjacent magnets in the circumferential direction on the outer circumferential surface of the rotor core, the salient poles having salient-pole-side opposing surfaces facing circumferential ends of the magnets on both sides in the circumferential direction, the plurality of magnets having magnet-side opposing surfaces facing the salient-pole-side opposing surfaces on both sides in the circumferential direction, the radial dimension of the surface is larger than the radial dimension of the magnet side opposing surface, the multiple magnets have a first region on the circumferential center side and a second region on the salient pole side, sandwiched between a first line that is parallel to a first line passing through the circumferential center of the magnet and the rotation axis when viewed from the rotation axis direction, and that passes through an intersection of a line along the salient pole side opposing surface and a curve along the outer peripheral surface of the rotor core, the magnetization orientation of the first region is a parallel orientation that is parallel to the first line, the overall magnetization orientation of the second region is a radial orientation that is along the radial direction, and the overall magnetization orientation of the salient pole side opposing surface is along the magnet side opposing surface .

The motor according to the present invention is characterized by comprising a stator having an annular stator core and a number of teeth protruding radially inward from the inner peripheral surface of the stator core, a coil attached to the teeth, and the rotor described above that is positioned radially inward relative to the teeth.

The brushless wiper motor according to the present invention is characterized by having the motor described above as a drive source for a wiper mounted on a vehicle.

The present invention makes it possible to easily manufacture the motor while minimizing increases in manufacturing costs, while also preventing demagnetization of the magnets due to the interlinkage magnetic flux of the stator coil.

1 is a perspective view of a brushless wiper motor according to an embodiment of the present invention; FIG. 2 is a cross-sectional view taken along line AA in FIG. 2 is a cross-sectional view taken along a radial direction of a stator and a rotor according to the embodiment of the present invention; FIG. FIG. 4 is an enlarged view of part B in FIG. 3 . FIG. 4 is an explanatory diagram showing an example of a flow of interlinkage magnetic flux to a salient pole of a rotor according to an embodiment of the present invention. 5 is a graph showing a change in demagnetization factor of a permanent magnet according to an embodiment of the present invention. 5 is a graph comparing the magnetization orientation of a permanent magnet in an embodiment of the present invention when it is parallel orientation and when it is radial orientation.

The rotor, motor, and brushless wiper motor according to an embodiment of the present invention will be described below with reference to the attached drawings.

<Brushless wiper motor>
Fig. 1 is a perspective view of a brushless wiper motor 1. Fig. 2 is a cross-sectional view taken along line AA in Fig. 1.
1 and 2, a brushless wiper motor 1 is a drive source for a wiper mounted on, for example, a vehicle. The brushless wiper motor 1 includes a motor unit 2 (an example of a motor in the claims), a speed reducer unit 3 that reduces the rotation speed of the motor unit 2 and outputs the reduced speed, and a controller unit 4 that controls the drive of the motor unit 2.
In the following description, when the term "axial direction" is used, it refers to the direction of the rotational axis of the shaft 31 of the motor section 2; when the term "circumferential direction" is used, it refers to the circumferential direction of the shaft 31 (the direction of rotation of the rotor 9 described below); and when the term "radial direction" is used, it refers to the radial direction of the shaft 31.

<Motor section>
The motor unit 2 includes a motor case 5, a substantially cylindrical stator 8 housed in the motor case 5, and a rotor 9 provided radially inside the stator 8 and rotatable relative to the stator 8. The motor unit 2 is a so-called brushless motor that does not require brushes to supply power to the stator 8.

<Motor case>
The motor case 5 is made of a material with excellent heat dissipation properties, such as aluminum die-casting. The motor case 5 is made up of a first motor case 6 and a second motor case 7, which are configured to be separable in the axial direction. The first motor case 6 and the second motor case 7 are each formed in a cylindrical shape with a bottom.
The first motor case 6 is molded integrally with the gear case 40 of the reduction gear unit 3 so that the bottom portion 10 is joined to the gear case 40. A through hole 10a is formed in approximately the center in the radial direction of the bottom portion 10, through which the shaft 31 of the rotor 9 can be inserted.

In addition, an outer flange portion 16 that protrudes radially outward is formed at the opening 6a of the first motor case 6. An outer flange portion 17 that protrudes radially outward is formed at the opening 7a of the second motor case 7. These outer flange portions 16, 17 are butted together to form the motor case 5 having an internal space. A stator 8 is arranged in the internal space of the motor case 5 so as to fit inside the first motor case 6 and the second motor case 7.

<Stator>
FIG. 3 is a cross-sectional view of the stator 8 and the rotor 9 taken along a radial direction.
As shown in Figures 2 and 3, the stator 8 has an annular stator core 20 integrally formed with a cylindrical core portion 21 and a plurality of teeth 22 (e.g., six in this embodiment) protruding radially inward from the core portion 21.
The stator core 20 is formed by stacking a plurality of metal plates in the axial direction. Note that 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, for example, by pressure molding soft magnetic powder.

The teeth 22 include an integrally molded teeth body 22a and a pair of flanges 22b. The teeth body 22a protrudes radially inward from the inner peripheral surface of the core portion 21. The flanges 22b extend circumferentially from the radially inner end of the teeth body 22a. The pair of flanges 22b are formed to extend circumferentially outward from the teeth body 22a. A dovetail-shaped slot 19 is formed between adjacent flanges 22b in the circumferential direction.

The inner circumferential surface of the core portion 21 and the teeth 22 are covered with a resin insulator 23. A coil 24 is wound around each tooth 22 from above the insulator 23. Each coil 24 generates a magnetic field for rotating the rotor 9 when power is supplied from the controller portion 4.

<Rotor>
The rotor 9 is rotatably provided radially inside the stator 8 via a small gap.
The rotor 9 includes a shaft 31, a rotor core 32 fixed to the shaft 31, four permanent magnets (an example of magnets in the claims) 33 fixed to the rotor core 32, and a substantially cylindrical magnet cover 70 that surrounds the rotor core 32 and the permanent magnets 33. Thus, in the motor section 2, the ratio of the number of magnetic poles of the permanent magnets 33 to the number of slots 19 (teeth 22) is, for example, 4:6.

The rotor 9 has a center line (axial center) C1 of the shaft 31 as its rotation axis, and rotates around this rotation axis as its radial center.
The shaft 31 is integrally formed with a worm shaft 44 (see FIG. 2 ) that constitutes the speed reducing portion 3 .
The rotor core 32 is fixed so as to be fitted onto the outside of the shaft 31. The rotor core 32 is formed in a cylindrical shape with the shaft 31 as its axis C1.

The rotor core 32 is formed by stacking multiple metal plates in the axial direction. Note that the rotor core 32 is not limited to being formed by stacking multiple metal plates in the axial direction, and may be formed, for example, by pressure molding soft magnetic powder.

A through hole 32a penetrating in the axial direction is formed at approximately the radial center of the rotor core 32. The shaft 31 is press-fitted into this through hole 32a. Note that the shaft 31 may be inserted relatively into the through hole 32a so that the rotor core 32 fits onto the outer circumferential surface of the shaft 31. In this case, the shaft 31 and the rotor core 32 may be fixed together by an adhesive or the like.
In the rotor core 32 , the arc center of the radially inner inner circumferential surface (i.e., the inner circumferential surface of the through hole 32 a ) and the arc center of the radially outer outer circumferential surface 32 b coincide with the position of the axis C<b>1 of the shaft 31 .

Furthermore, four salient poles 35 are provided at equal intervals in the circumferential direction on the outer peripheral surface 32b of the rotor core 32. The salient poles 35 are formed so as to protrude radially outward integrally with the rotor core 32 and extend over the entire axial direction of the rotor core 32. A rounded chamfered portion 32c is formed at the connection between the base end (radially inner end) of the salient pole 35 and the outer peripheral surface 32b of the rotor core 32. The salient poles 35 are formed by stacking multiple metal plates in the axial direction, similar to the rotor core 32.

On the outer peripheral surface 32 b of the rotor core 32 formed in this manner, the spaces between two adjacent salient poles 35 in the circumferential direction are each configured as a magnet housing portion 36 .
That is, the rotor 9 is a surface permanent magnet (SPM) type rotor having permanent magnets 33 for a field magnet on an outer peripheral surface 32 b of a rotor core 32, and is an inset type rotor having salient poles 35 that protrude radially outward from the rotor core 32 between the permanent magnets 33 arranged in the circumferential direction.

The tip surface (the radially outer end surface) 35a of the salient pole 35 has a recess 38 extending in the axial direction. Furthermore, the tip surface 35a of the salient pole 35 has rounded chamfered portions 35b formed at both circumferential corners. The salient pole 35 is also formed so that the two circumferentially opposing side surfaces 35c are parallel to the protruding direction. In other words, the salient pole 35 is formed so that the circumferential width dimension is uniform in the protruding direction.

<Permanent magnet>
FIG. 4 is an enlarged view of part B in FIG.
3 and 4, the four permanent magnets 33 are arranged in four magnet storage sections 36 provided on the outer circumferential surface 32b of the rotor core 32. Each permanent magnet 33 is fixed to the rotor core 32 in the magnet storage section 36 by, for example, an adhesive.

The permanent magnet 33 is, for example, a ferrite magnet or a rare earth magnet. The permanent magnet 33 is formed in a tile shape. In the permanent magnet 33, the arc center Ci of the inner peripheral surface 33b on the radially inner side coincides with the position of the axis 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, the radial thickness of the permanent magnet 33 at the ends 33s on both circumferential sides around the axis C1 of the shaft 31 is smaller than the radial thickness at the circumferential center 33c. Accordingly, the gap between the radially outer outer peripheral surface 33a of the permanent magnet 33 and the inner peripheral surface of the teeth 22 is smallest at the circumferential center 33c of the permanent magnet 33, and tends to increase as it moves away from the circumferential center 33c circumferentially outward.

The inner peripheral surface 33b of the permanent magnet 33 is in contact with almost the entire outer peripheral surface 32b of the rotor core 32. In addition, each circumferential side surface 33d on both sides of the permanent magnet 33 in the circumferential direction is in contact with the side surface 35c of the salient pole 35. The circumferential side surface 33d is smoothly connected to the inner peripheral surface 33b on the radially inner side via the arc surface 33f. The radius of curvature of the arc surface 33f is larger than the radius of curvature of the rounded chamfered portion 32c formed at the connection between the outer peripheral surface 32b of the rotor core 32 and the base end of the salient pole 35. Therefore, the arc surface 33f and the rounded chamfered portion 32c do not come into contact with each other. Therefore, the inner peripheral surface 33b of the permanent magnet 33 is reliably in contact with the outer peripheral surface 32b of the rotor core 32. In addition, the circumferential side surface 33d of the permanent magnet 33 is reliably in contact with the side surface 35c of the salient pole 35.

Next, the magnetization orientation of the permanent magnet 33 will be described in detail.
The permanent magnet 33 has two regions R1, R2 (a first region R1 and a second region R2) having different magnetization orientations.
The two regions R1 and R2 will now be described. A straight line passing through the circumferential center 33c of the permanent magnet 33 and the axis C1 when viewed from the axial direction is defined as a first straight line L1. A straight line along the side surface 35c of the salient pole 35 is defined as a complementary straight line Lh. A curved line along the outer peripheral surface 32b of the rotor core 32 is defined as Lk. The intersection of the complementary straight line Lh and the curve Lk is defined as an intersection point C2. A straight line passing through this intersection point C2 and parallel to the first straight line L1 is defined as a second straight line L2.

The permanent magnet 33 has a first region R1 on the circumferential center 33c side with respect to the second straight line L2. The salient pole 35 side region with respect to the second straight line L2 is set as the second region R2. That is, one permanent magnet 33 has one first region R1 and two second regions R2 arranged on both sides of the first region R1 in the circumferential direction with the second straight line L2 in between. When viewed from the axial direction, the first region R1 is a substantially rectangular region, and the second region R2 is a substantially triangular region tapering radially inward.
The entire first region R1 has a parallel orientation (see arrow PM in FIG. 4) in which the magnetization is aligned parallel to the first straight line L1, whereas the entire second region R2 has a radial orientation (see arrow RM in FIG. 4) in which the magnetization is aligned along the radial direction.

The permanent magnets 33 configured in this manner are arranged so that the magnetization orientation of adjacent permanent magnets 33 in the circumferential direction is in the opposite direction. In other words, the four permanent magnets 33 are arranged so that the magnetic poles alternate in the circumferential direction. In other words, the permanent magnets 33 with the outer circumferential side as the north pole and the permanent magnets 33 with the outer circumferential side as the south pole are arranged so that they are adjacent in the circumferential direction. As a result, the salient poles 35 of the rotor core 32 arranged between the adjacent permanent magnets 33 in the circumferential direction are located at the boundary (pole boundary) of the magnetic poles.

<Reduction section>
Returning to FIGS. 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 gear mechanism 41 housed within the gear case 40 .
The gear case 40 is made of a material with excellent heat dissipation properties, such as aluminum die casting. The gear case 40 has a box-like outer shape with an opening 40a on one side. The gear case 40 has a gear housing 42 that houses a worm reduction mechanism 41 therein. In addition, an opening 43 is formed in a side wall 40b of the gear case 40 at a location where the first motor case 6 is integrally molded, which allows the through hole 10a of the first motor case 6 to communicate with the gear housing 42.

Further, a substantially cylindrical bearing boss 49 is provided to protrude from the bottom wall 40c of the gear case 40.
The bearing boss 49 is provided to rotatably support the output shaft 48 of the worm reduction mechanism 41, and is provided with a sliding bearing (not shown) on its inner circumferential surface.
Furthermore, 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.
In addition, a plurality of ribs 52 are provided on the outer circumferential surface of the bearing boss 49. This ensures that the bearing boss 49 has the desired rigidity.

The worm reduction mechanism 41 housed in the gear housing portion 42 is composed of a worm shaft 44 and a worm wheel 45 that meshes with the worm shaft 44 .
The worm shaft 44 is disposed coaxially with the shaft 31 of the motor unit 2. Both ends of the worm shaft 44 are rotatably supported by bearings 46, 47 provided in the gear case 40. The end of the worm shaft 44 on the motor unit 2 side protrudes through the bearing 46 until it reaches the opening 43 of the gear case 40. The protruding 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 together. The worm shaft 44 and the shaft 31 may be integrally formed by molding the worm shaft portion and the rotating shaft portion from one base material.

The worm wheel 45 that meshes with the worm shaft 44 has an output shaft 48 provided at the radial center of the worm wheel 45. The output shaft 48 is arranged coaxially with the direction of the rotation axis of the worm wheel 45 and protrudes outside the gear case 40 via a bearing boss 49 of the gear case 40. A spline 48a that can be connected to an electrical component (not shown) is formed at the protruding tip of the output shaft 48.

A sensor magnet (not shown) is provided in the radial center of the worm wheel 45, opposite the side from which the output shaft 48 protrudes. This sensor magnet constitutes one side of a rotational position detection unit 60 that detects the rotational position of the worm wheel 45. A magnetic detection element 61 that constitutes the other side of the rotational position detection unit 60 is provided in the controller unit 4 that is disposed opposite the worm wheel 45 on the sensor magnet side of the worm wheel 45 (the opening 40a side of the gear case 40).

<Controller section>
The controller unit 4, which controls the drive of the motor unit 2, has a controller board 62 on which a magnetic detection element 61 is mounted, and a cover 63 provided to close the opening 40a of the gear case 40. The controller board 62 is disposed opposite 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 multiple conductive patterns (not shown) are formed. The terminals of the coils 24 drawn from the stator core 20 of the motor unit 2 are connected to the controller board 62, and a terminal (not shown) of the connector 11 provided on the cover 63 is electrically connected to the controller board 62. In addition to the magnetic detection element 61, the controller board 62 also has a power module (not shown) implemented, which is made up of switching elements such as FETs (field effect transistors) that control the current supplied to the coils 24. Furthermore, the controller board 62 also has a capacitor (not shown) and the like implemented to smooth the voltage applied to the controller board 62.

The cover 63 that covers the controller board 62 configured in this manner is made of resin. The cover 63 is formed so as to bulge outward slightly. The inner surface of the cover 63 serves as the controller housing section 56 that houses the controller board 62 and the like.
A connector 11 is integrally formed on the outer periphery of the cover 63. This connector 11 is formed so as to be able to be fitted with a connector extending from an external power source (not shown). A controller board 62 is electrically connected to a terminal (not shown) of the connector 11. This allows power from the external power source to be supplied to the controller board 62.

Furthermore, a fitting portion 81 that fits with the end of the side wall 40b of the gear case 40 is protrudingly formed on the opening edge of the cover 63. The fitting portion 81 is composed of two walls 81a, 81b along the opening edge of the cover 63. The end of the side wall 40b of the gear case 40 is inserted (fitted) between these two walls 81a, 81b. This forms a labyrinth portion 83 between the gear case 40 and the cover 63. This 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 together by tightening bolts (not shown).

<Operation of Brushless Wiper Motor>
Next, the operation of the brushless wiper motor 1 will be described.
In the brushless wiper motor 1, power supplied to the controller board 62 via the connector 11 is selectively supplied to each coil 24 of the motor section 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 attraction or repulsion force (magnetic torque) between the effective magnetic flux formed by the permanent magnets 33 of the rotor 9.

In addition, the salient poles 35 of the rotor core 32 protrude in a direction that facilitates the flow of linkage magnetic flux from the stator 8 (teeth 22), and generate a reluctance torque that rotates the rotor core 32 so as to reduce the magnetic resistance (reluctance) of the magnetic path of the linkage magnetic flux.
These magnetic torques and reluctance torques cause the rotor 9 to rotate continuously.
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 then transmitted to an output shaft 48 that is connected to the worm wheel 45, and the output shaft 48 drives a desired electrical component.

The detection signal of the rotational 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) that includes a processor such as a CPU, a ROM (Read Only Memory) that stores programs, a RAM (Random Access Memory) that temporarily stores data, and electronic circuits such as a timer.

In addition, at least a part of the external device (not shown) may be an integrated circuit such as an LSI (Large Scale Integration). The external device (not shown) controls the switching timing of the switching elements of the power module (not shown) based on the rotational position detection signal of the worm wheel 45, and controls the drive of the motor unit 2. Note that the output of the drive signal of the power module and the drive control of the motor unit 2 may be performed by the controller unit 4 instead of the external device (not shown).

<Function of permanent magnets>
Next, the function of the permanent magnet 33 will be described with reference to FIG.
5 is an explanatory diagram showing an example of a flow of interlinkage magnetic flux to the salient poles 35 of the rotor 9. FIG 5 corresponds to the above-mentioned FIG 4.
5, when the rotor 9 rotates and flux linkage due to the coils 24 of the stator 8 flows from the teeth 22 on the front side in the rotation direction R toward the salient poles 35, the flux linkage tries to pass near the salient poles 35 of the permanent magnets 33, that is, near the second regions R2 of the permanent magnets 33. In other words, the flux linkage tries to penetrate into the second regions R2 of the permanent magnets 33. The direction of the flow of the flux linkage near the second regions R2 is oblique to the radial direction, from the radial outside of the rotor 9 toward the tips of the salient poles 35 (see arrows Y1 in FIG. 5).

Here, when the flux linkage flows and penetrates into the interior of the permanent magnet 33, a demagnetizing field is generated in the permanent magnet 33. The flux linkage easily flows (penetrates) along the magnetization orientation of the permanent magnet 33. However, the magnetization orientation of the second region R2 of the permanent magnet 33 near the salient pole 35 is radial (arrow RM) with respect to the direction of the flux linkage flow toward the salient pole 35 (arrow Y1). Since the radial orientation is along the radial direction, it intersects with the flux linkage flow near the second region R2. As a result, the flux linkage does not easily flow (penetrate) into the second region R2.

Therefore, according to the rotor 9 of this embodiment, by making the magnetization orientation of the second region R2, which is the circumferential end portion of the permanent magnet 33 adjacent to the salient pole 35, radially oriented, it is possible to suppress demagnetization caused by the flux linkage of the coil 24 of the stator 8. In other words, the second region R2 is a region where the flux linkage is likely to be attracted toward the salient pole 35, that is, the region on the salient pole 35 side centered on the second straight line L2 of the permanent magnet 33. Therefore, by actively making the magnetization orientation of the parts of the permanent magnet 33 that are easily affected by the flux linkage intersect with the flow of the flux linkage, it is possible to effectively prevent the flux linkage from penetrating the permanent magnet 33.

FIG. 6 is a graph showing the change in the demagnetization rate of the permanent magnet 33 when the vertical axis represents the demagnetization rate [%] of the permanent magnet 33 in the second region R2 and the horizontal axis represents the current value [A] supplied to the coil 24, and comparing the changes by magnetization orientation.
As shown in Figure 6, it can be seen that the demagnetization rate is reduced when the magnetization orientation of the second region R2 is parallel, or when the magnetization orientation is reverse radially oriented (see the arrow indicated by the dashed double-dotted line in Figure 3) toward the circumferential center 33c on the outer circumferential surface 33a of the permanent magnet 33.

In addition, according to the rotor 9 of this embodiment, the magnetization orientation of the first region R1 of the permanent magnet 33 is parallel, which improves the motor characteristics of the brushless wiper motor 1. This will be described in detail below.

FIG. 7 is a graph showing the effective magnetic flux [μWb] of the permanent magnet 33 on the vertical axis, comparing the case where the magnetization orientation of the permanent magnet 33 is parallel orientation with the case where the magnetization orientation is radial orientation.
7, it can be seen that when the magnetization orientation of the permanent magnet 33 is parallel, the effective magnetic flux is greater than when the magnetization orientation is radial. Therefore, by setting the magnetization orientation of the first region R1, which is located away from the salient pole 35 and is less susceptible to the influence of interlinkage magnetic flux, to the parallel orientation, it is possible to sufficiently ensure the effective magnetic flux of the permanent magnet 33 when the brushless wiper motor 1 is driven. This makes it possible to improve the motor characteristics of the brushless wiper motor 1.

In addition, since the magnetization orientation of the second region R2 is merely changed relative to the magnetization direction of the first region R1, there is no need to change the material of the first region R1 and the second region R2 of the permanent magnet 33, for example. This makes it possible to easily manufacture the permanent magnet 33 and to suppress increases in manufacturing costs.
By radially aligning the entire second region R2, demagnetization of the entire second region R2 can be suppressed.

The present invention is not limited to the above-described embodiment, and includes various modifications to the above-described embodiment without departing from the spirit of the present invention.
For example, in the above embodiment, the brushless wiper motor 1 is given as an example of a motor, but the motor according to the present invention is not limited to the brushless wiper motor 1. For example, the motor may be a drive source for various electrical components (e.g., a power window, a sunroof, an electric seat, etc.) mounted on a vehicle, or a drive source mounted on various devices other than a vehicle.

In the above embodiment, in the rotor core 32, the arc center Co of the outer circumferential surface 33a is eccentric with respect to the axis C1 of the shaft 31, but this is not limited thereto.
For example, the arc center Co of the radially outer peripheral surface 33a of the permanent magnet 33 may coincide with the axis C1 of the shaft 31. In this case, the radial thickness between the outer peripheral surface 33a and the inner peripheral surface 33b of the permanent magnet 33 is uniform over the entire circumferential direction. Accordingly, the gap between the radially outer peripheral surface 33a of the permanent magnet 33 and the inner peripheral surface of the tooth 22 is constant over the entire circumferential direction.

In the above embodiment, the tip surface 35a of the salient pole 35 has a recess 38 formed therein, but this is not limited thereto, and the recess 38 may be omitted.

In the above embodiment, the permanent magnet 33 has been described as having a parallel orientation in which the magnetization orientation of the entire first region R1 is parallel to the first straight line L1. However, this is not limited to this. Instead of a parallel orientation, the magnetization orientation of the first region R1 can adopt various magnetization orientations, such as a radial orientation in the radial direction, a reverse radial orientation toward the circumferential center portion 33c of the outer circumferential surface 33a of the permanent magnet 33, and a polar anisotropic orientation. The entire first region R1 does not have to have the same magnetization orientation.

In the above embodiment, the permanent magnet 33 is radially oriented, in which the magnetization orientation of the entire second region R2 is in the radial direction. However, this is not limited to the above, and it is sufficient that at least a portion of the second region R2 is radially oriented. The orientation of the portions of the second region R2 other than the radial orientation may be the same as that of the first region R1. However, when only a portion of the second region R2 is radially oriented, there is a possibility that the magnetization may be slightly demagnetized compared to when the entire second region R2 is radially oriented.

1...Brushless wiper motor, 2...Motor section (motor), 3...Reduction section, 4...Controller section, 5...Motor case, 6...First motor case, 6a, 7a...Opening, 7...Second motor case, 8...Stator, 9...Rotor, 10...Bottom, 10a...Through hole, 11...Connector, 16...Outer flange section, 17...Outer flange section, 19...Slot, 20...Stator core, 21...Core section, 22...Teeth, 22a...Teeth body, 22b...Flange section, 23...Insulator, 24...Coil, 31...Shaft, 32...Rotor core, 32a...Through hole, 32b...Outer surface, 32c...Round chamfered section, 33...Permanent magnet (magnet), 33a...Outer surface, 33b...Inner surface, 33c...Circumferential center, 33d...Circumferential side (magnet side facing surface) , 33f... arc surface, 33s... end portion, 35... salient pole, 35a... tip surface, 35b... rounded chamfered portion, 35c... side surface (surface facing the salient pole) , 36...magnet storage section, 38...recess, 40...gear case, 40a, 43...opening, 40b...side wall, 40c...bottom wall, 41...worm reduction mechanism, 42...gear storage section, 44...worm shaft, 45...worm wheel, 46, 47...bearing, 48...output shaft, 48a...spline, 49...bearing boss, 52...rib, 56...controller storage section, 60...rotational position detection section, 61...magnetic detection element, 62...controller board, 63...cover, 70...magnet cover, 81...fitting section, 81a...wall, 81b...wall, 83...labyrinth section, C1...axis center (rotation axis), C2...intersection, L1...first straight line, L2...second straight line, Lh...complementary straight line, Lk...curve, R1...first region, R2...second region, PM...parallel orientation, RM...radial orientation

Claims (4)

A shaft that rotates about a rotation axis;
a rotor core that holds the shaft and rotates about the rotation axis;
A plurality of magnets are arranged in a line along a circumferential direction on an outer peripheral surface of the rotor core;
a salient pole protruding radially outwardly of the rotor core between adjacent magnets on the outer circumferential surface of the rotor core;
Equipped with
The salient pole has a salient-pole-side opposing surface that faces an end of the magnet in the circumferential direction on both sides in the circumferential direction,
The magnets each have a magnet-side facing surface that faces the salient pole-side facing surface on both sides in the circumferential direction,
a dimension of the salient pole side facing surface along a radial direction is greater than a dimension of the magnet side facing surface along a radial direction,
the plurality of magnets have a first region on the circumferential center side and a second region on the salient pole side, the first region being parallel to a first line passing through the circumferential center of the magnet and the rotation axis when viewed from the rotation axis direction, and the second line passing through an intersection of a line along the salient pole side opposing surface and a curve along the outer circumferential surface of the rotor core;
The magnetization orientation of the first region is a parallel orientation that is parallel to the first line,
The overall magnetization orientation of the second region is a radial orientation that is oriented along a radial direction,
The entire magnetization orientation of the magnet-side facing surface is aligned with the magnet-side facing surface.
A rotor characterized by: a stator having an annular stator core and a plurality of teeth protruding radially inward from an inner peripheral surface of the stator core;
A coil attached to the tooth;
the rotor according to claim 1 , the rotor being disposed radially inward with respect to the plurality of teeth;
A motor comprising: The plurality of teeth include
a teeth main body protruding inward along the radial direction from the inner circumferential surface of the stator core;
a pair of flange portions extending outward along the circumferential direction from the radially inner ends of the teeth main bodies;
having
A dimension of the first region along the circumferential direction is larger than a dimension of the tooth body along the circumferential direction and smaller than a dimension obtained by adding the dimension of the tooth body along the circumferential direction to each of the pair of flange portions along the circumferential direction.
3. The motor according to claim 2. 4. A brushless wiper motor comprising the motor according to claim 2 or 3 as a drive source for a wiper mounted on a vehicle.

Images