JP2021180585A - Brushless motor - Google Patents

Abstract

To reduce the weight of a brushless motor.SOLUTION: A brushless motor includes a stator with a stator core, and a rotor with a rotor core 22 and a ring-shaped magnet, and the stator core includes a plurality of teeth, and the rotor is arranged inside the plurality of teeth. The magnet is magnetized such that a magnetic pole is formed on the outer peripheral portion of the magnet facing each of the plurality of teeth. The rotor core 22 is composed of a plurality of rotor core sheets 22a formed in a non-circular shape having an arc-shaped portion and a non-arc-shaped portion in a planar shape, and the plurality of rotor core sheets 22a are laminated alternately such that the non-arc-shaped portions of the rotor core sheets 22a adjacent to each other in the stacking direction do not overlap in the circumferential direction of the magnet.SELECTED DRAWING: Figure 10

Description

The present invention relates to a brushless motor.

Brushless motors are known as drive sources for sunroof devices mounted on vehicles such as automobiles. There are generally two types of brushless motors, SPM (Surface Permanent Magnet) and IPM (Interior Permanent Magnet). In the SPM type brushless motor, a segment magnet or a ring magnet is used as a magnet. As a magnetizing method for increasing the magnetic flux of the ring magnet, extremely anisotropic magnetizing is known in which magnetism is performed so that a magnetic pole is formed on the outer peripheral surface of the ring magnet.

A brushless motor in which magnetic poles are formed by polar anisotropy is disclosed in, for example, Patent Document 1.

Japanese Unexamined Patent Publication No. 2019-161933

In the brushless motor magnetized by the above-mentioned extremely different magnetization, magnetic flux leakage does not occur inside the ring magnet due to the magnetic circuit structure of the Halbach array of the ring magnets. As a result, in the brushless motor as described above, the magnetic circuit inside the ring magnet and the rotor core, which are indispensable for the motor using the radial anisotropic ring magnet, become unnecessary. As a result, it becomes possible to dispose a non-magnetic resin or the like inside the ring magnet, and it is conceivable to fill the inside of the ring magnet with the resin or the like to reduce the weight of the brushless motor.

However, when the inside of the ring magnet is filled with resin, there are concerns about the strength of the resin and deterioration over time. Therefore, from the viewpoint of strength, it is conceivable to arrange a metal body inside the ring magnet, but in that case, there is a concern that the weight of the brushless motor will increase and the cost will increase.

The brushless motor described in Patent Document 1 has a structure in which a rotor core is not arranged inside a ring magnet and the ring magnet is directly fixed to a shaft which is a rotation axis. In such a structure, there is a concern that the shaft becomes thick and the weight of the brushless motor becomes heavy.

An object of the present invention is to provide a brushless motor having a reduced weight.

One aspect of the present invention is a brushless motor including a stator core, a stator having a winding wound around the stator core, and a rotor core and a rotor having a ring-shaped magnet provided on the outer periphery of the rotor core. , The stator core has a plurality of teeth extending radially inward of the stator core, the rotor is rotatably arranged inside the plurality of teeth, and the magnet is attached to each of the plurality of teeth. The rotor core is magnetized so that a magnetic pole is formed on the outer peripheral portion of the magnets facing each other, and the rotor core has a plurality of plate-like shapes formed in a non-circular shape including an arc-shaped portion and a non-arc-shaped portion in a planar shape. The plurality of plate-shaped members are laminated in a staggered manner so that the non-arc-shaped portions of the plate-shaped members adjacent to each other in the stacking direction do not overlap in the circumferential direction of the magnet.

According to the present invention, the weight of the brushless motor can be reduced.

It is a schematic diagram which shows the sunroof device mounted on the roof of a vehicle. It is a perspective view of the sunroof motor apparatus of embodiment of this invention. It is a perspective view which shows the meshing state of the worm and the worm wheel formed in the shaft of the brushless motor incorporated in the sunroof motor apparatus shown in FIG. 2. It is sectional drawing which follows the AA line of FIG. It is a perspective view of the rotor core unit of the brushless motor shown in FIG. It is sectional drawing of the rotor core unit shown in FIG. It is a top view of the rotor core sheet in the rotor core unit shown in FIG. FIG. 3 is a plan view showing a rotor core structure formed by laminating the rotor core sheets shown in FIG. 7. It is a side view of the rotor core structure shown in FIG. It is a perspective view of the rotor core structure shown in FIG. It is a top view which shows the yield state of the rotor core sheet of the comparative example. It is a top view which shows the yield state of the rotor core sheet of embodiment of this invention. It is a top view of the rotor core sheet of the 1st modification of this invention. It is a top view of the rotor core sheet of the 2nd modification of this invention. It is a top view of the rotor core sheet of the 3rd modification of this invention. It is a top view which shows the rotor core structure of the 4th modification made by laminating the rotor core sheets of this invention. It is a side view of the rotor core structure shown in FIG. It is a perspective view of the rotor core structure shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, a sunroof motor device on which the brushless motor of the present embodiment is mounted will be described. As shown in FIG. 1, the sunroof device 10 includes a roof panel 11. The roof panel 11 opens and closes the opening 14 formed in the roof 13 of the vehicle 12. A pair of shoes 15a and 15b are fixed to both sides of the roof panel 11 along the vehicle width direction (vertical direction in the drawing). Further, guide rails 16 extending in the front-rear direction (left-right direction in the figure) of the vehicle 12 are fixed on both sides of the opening 14 of the roof 13 along the vehicle width direction. The pair of shoes 15a and 15b are guided by the corresponding pair of guide rails 16, so that the roof panel 11 can be moved in the front-rear direction of the vehicle 12, that is, can be opened and closed.

One ends of the drive cables 17a and 17b with gears are connected to each of the shoes 15b arranged on the rear side (right side in the drawing) of the vehicle 12. The other ends of these drive cables 17a and 17b are routed to the front side (left side in the figure) of the vehicle 12 with respect to the opening 14.

A sunroof motor device 20 is mounted inside the roof 13 arranged between the opening 14 and the windshield 18 on the front side of the vehicle 12. The other ends of the pair of drive cables 17a and 17b are meshed with the output gear 42b provided in the sunroof motor device 20. Here, when the sunroof motor device 20 is driven, the pair of shoes 15a and 15b are moved in opposite directions as the output gear 42b rotates. As a result, the roof panel 11 is pushed and pulled by the pair of drive cables 17a and 17b via the pair of shoes 15b, whereby the roof panel 11 is automatically opened and closed.

Next, the sunroof motor device 20 of the present embodiment will be described. In the following description, the term "axial direction" refers to the rotation axis direction of the motor shaft, the term "circumferential direction" refers to the circumferential direction of the shaft, and the term "diametrical direction" refers to the diameter of the shaft. It shall refer to the direction.

As shown in FIG. 2, the sunroof motor device 20 includes a brushless motor 21 and a gear portion 40. The brushless motor 21 has a stator 29 including an annular stator core 25 shown in FIG. 4 and a coil (winding wire) 28 wound around the stator core 25. The stator core 25 has a plurality of teeth 30 extending inward in the radial direction. Further, the brushless motor 21 has a rotor 24 rotatably arranged inside the teeth 30. The rotor 24 has a rotor core 22 and a ring-shaped magnet 23 provided on the outer periphery of the rotor core 22. Further, the brushless motor 21 has a shaft 27 provided inside the stator core 25 in the radial direction and rotating around the rotation axis 31 shown in FIG. The rotor core 22 is fixed to the shaft 27 and has the rotation axis 31 as the radial center. As shown in FIG. 3, the shaft 27 is rotatably supported by a ball bearing 44.

Further, as shown in FIG. 4, the stator core 25 includes a plurality of teeth 30 protruding inward in the radial direction of the stator core 25 from the inner peripheral surface of the stator core 25, and an insulating film 33 is provided on each of the plurality of teeth 30. The coil 28 is wound through the coil 28.

Next, as shown in FIG. 2, the gear portion 40 is provided with a gear case 41. The opening portion of the gear case 41 is closed by a gear cover (not shown). This gear cover is formed in a substantially flat plate shape by a resin material such as plastic, and can be easily attached to the gear case 41 by a so-called snap-fit engagement structure.

Further, the gear case 41 is provided with a worm wheel accommodating portion 41a. The worm wheel accommodating portion 41a is provided so as to be recessed in the thickness direction of the gear case 41 and on the side opposite to the gear cover side. A worm wheel 42 forming a deceleration mechanism is rotatably housed in the worm wheel accommodating portion 41a.

The worm wheel 42 is formed of a resin material such as plastic in a substantially disk shape, and the worm 43a provided on the worm shaft 43 formed in succession with the shaft 27 on the radial outer side thereof, as shown in FIG. A tooth portion 42a is formed in which the wheels are meshed with each other. Further, the axial proximal end side of the output gear 42b is fixed to the center of rotation of the worm wheel 42. Here, the output gear 42b is made of steel, and its axial intermediate portion is rotatably supported by the boss portion of the gear case 41 shown in FIG. The axial tip side of the output gear 42b extends to the outside of the gear case 41, whereby the other ends of the pair of drive cables 17a and 17b are meshed with the tip end side of the output gear 42b (FIG. FIG. 1).

Here, the operation of the sunroof motor device 20 will be described.

In the sunroof motor device 20, the electric power supplied from the outside to the controller board (not shown) via the terminal 32 shown in FIG. 2 is selectively supplied to each coil 28 of the brushless motor 21 shown in FIG. Then, a predetermined interlinkage magnetic flux is formed in the stator 29 (teeth 30), and a magnetic attraction force or a repulsive force is formed between the interlinkage magnetic flux and the effective magnetic flux formed by the magnet 23 provided in the rotor core 22. Occurs. As a result, the rotor core 22 continuously rotates.

Then, when the rotor core 22 rotates, the worm shaft 43 integrated with the shaft 27 shown in FIG. 3 rotates, and further, the worm wheel 42 meshing with the worm shaft 43 rotates. Then, the output gear 42b connected to the worm wheel 42 rotates, and a desired electrical component or the like can be driven.

Next, the ring-shaped magnet 23 mounted on the brushless motor 21 of the present embodiment will be described. As shown in FIG. 4, the magnet 23 is magnetized so that magnetic poles such as N pole and S pole are formed on the outer peripheral surface 23a on the outer peripheral portion of the magnet 23 facing each of the plurality of teeth 30. The magnet 23 magnetized in this way is also referred to as a polar oriented magnet 23. Specifically, in the ring-shaped magnet 23, as a means for increasing the magnetic flux 23b, polar anisotropic magnetism is applied so as to form a magnetic pole on the outer peripheral surface 23a of the outer peripheral portion of the magnet 23. .. As a result, magnetic poles such as N pole and S pole are formed on the outer peripheral surface 23a facing each of the plurality of teeth 30. In the brushless motor 21 magnetized by the above-mentioned polar anisotropy, a magnetic material is arranged inside the ring-shaped magnet 23 because magnetic flux leakage does not occur inside the ring-shaped magnet 23. It is not mandatory to do.

Therefore, as shown in the rotor core unit 26 of FIGS. 5 and 6, the rotor core 22 in the brushless motor 21 of the present embodiment is formed into a non-circular shape having an arc-shaped portion and a non-arc-shaped portion. A plurality of rotor core sheets (plate-shaped members, also referred to as rotor core plates) 22a are laminated. A rotor core 22 in which a plurality of rotor core sheets 22a are laminated is arranged inside the ring-shaped magnet 23. As shown in FIG. 7, each of the rotor core sheets 22a of the present embodiment is formed in a non-circular shape having an arc-shaped portion and a non-arc-shaped portion in a planar shape. As shown in FIGS. 8 to 10, the plurality of rotor core sheets 22a each having a non-circular planar shape have the non-arc-shaped portions of the rotor core sheets 22a adjacent to each other in the stacking direction as shown in FIG. The magnets 23 are stacked alternately so as not to overlap in the circumferential direction.

In this embodiment, the case where the non-arc-shaped portion is a straight line portion 22b made of a straight line will be described. Therefore, each planar shape of the rotor core sheet 22a of the present embodiment includes a pair of straight portions (non-arc-shaped portions) 22b, a pair of arc-shaped portions 22c connected to each end of the pair of straight portions 22b, and a pair of arcuate portions 22c. It is an oval shape consisting of. In other words, the planar shape of the rotor core sheet 22a is a two-way shape as if the opposite side portions of the circular rotor core sheet are scraped off. A through hole 22e in which the shaft 27 shown in FIG. 5 is arranged is formed near the center of each rotor core sheet 22a. That is, the rotor core 22 in which a plurality of rotor core sheets 22a are laminated is fixed to the shaft 27 that is press-fitted into the through hole 22e.

Further, in the rotor core sheet 22a, the ends on both sides in the direction along the straight line portion 22b are arcuate portions 22c.

In other words, as shown in FIG. 7, each rotor core sheet 22a is arranged around the through hole 22e and has a straight line with a region of the sheet central portion 22i having straight line portions 22b on both sides. It is arranged on both sides of the seat central portion 22i in the direction along the portion 22b, and is composed of a region of the end portion 22d including the arcuate portion 22c.

That is, in the brushless motor 21 of the present embodiment, the rotor cores 22 provided inside are each formed by laminating a plurality of rotor core sheets 22a formed in an oval shape (two-sided shape). As a result, the volume of the rotor core 22 can be reduced as compared with the rotor core formed by laminating circular rotor core sheets. Then, in order to balance the weight of the brushless motor 21 during rotation, the plurality of rotor core sheets 22a are staggered so that the non-arc-shaped portions of the rotor core sheets 22a adjacent to each other in the stacking direction do not overlap in the circumferential direction of the magnet 23. It is laminated in. That is, the rotor core sheets 22a are alternately laminated so that the non-arc-shaped portions do not overlap in the circumferential direction of the magnet 23, whereby the motor provided with the rotor core formed by laminating the circular rotor core sheets and the motor during rotation The motor characteristics of are made to be the same.

Further, the rotor core sheet 22a of the present embodiment is formed of, for example, an iron-based metal. However, the rotor core sheet 22a may be formed of a metal other than iron, or may be formed of a resin other than metal or the like.

In this embodiment, as shown in FIGS. 8 to 10, the plurality of rotor core sheets 22a are arranged in the circumferential direction of the magnet 23 shown in FIG. 5 (circumferential direction of the shaft 27) of the rotor core sheets 22a adjacent to each other in the stacking direction. ), The straight portions 22b are stacked alternately so that the angle formed by them is 90 ° (R = 90 °). In other words, as shown in FIG. 8, the plurality of rotor core sheets 22a are arranged every other so that the angle formed by the straight portions 22b of the rotor core sheets 22a adjacent to each other in the stacking direction is 90 ° (R = 90 °). They are stacked alternately by turning to. As a result, the end portion 22d of each rotor core sheet 22a has a structure protruding from the sheet center portion 22i of the rotor core sheets 22a adjacent to each other in the stacking direction.

Therefore, in the rotor core 22 shown in FIG. 10, the space portion 22f shown in FIG. 9 is between the end portions 22d of the rotor core sheets 22a adjacent to each other in the stacking direction of the plurality of rotor core sheets 22a laminated in the same direction in the circumferential direction. Is formed.

The effect obtained by the brushless motor 21 of the present embodiment will be described. In the brushless motor 21, the rotor core 22 provided inside the rotor core 22 is formed by laminating a plurality of rotor core sheets 22a formed in a non-circular shape having an arcuate portion and a non-arc-shaped portion in a planar shape. In the present embodiment, the non-circular shape is an oval shape (also referred to as a two-way shape). As a result, the volume of the rotor core 22 can be reduced as compared with the rotor core formed by laminating circular rotor core sheets. As a result, the weight of the brushless motor 21 can be reduced and the material cost can be reduced.

Further, since each of the plurality of rotor core sheets 22a is formed of an iron-based metal, the strength of the rotor core 22 can be increased as compared with the case where each of the plurality of rotor core sheets 22a is formed of a resin. Further, it is possible to delay the progress of aging deterioration and extend the life of the rotor core 22.

Further, when the magnet 23 is adhered to the rotor core 22, as shown in FIG. 6, the space portion 22f between the end portions of the rotor core sheets 22a adjacent to each other in the stacking direction of the plurality of rotor core sheets 22a (see FIG. 9). Can be used as an adhesive pool. That is, by filling the space 22f between the end portions with the adhesive 19 for fixing the magnet 23 to the rotor core 22, the bonding strength of the magnet 23 to the rotor core 22 can be increased.

Further, when the magnet 23 is molded by injection molding, the anchor effect of the magnet 23 on the rotor core 22 can be enhanced by filling the space portion 22f with a magnet material.

Further, by making the planar shape of the rotor core sheet 22a a non-circular shape such as an oval shape (two-sided shape), the yield of the rotor core sheet 22a can be increased. The comparative example shown in FIG. 11 shows the number of circular rotor core sheets 22h taken from the base material 34, and in this case, the number of taken rotor core sheets 22h from the base material 34 is six. On the other hand, in the case of the rotor core sheet 22a of the present embodiment shown in FIG. 12, since the planar shape of the rotor core sheet 22a is an oval shape (two-sided shape), the base material 34 having the same size is used. The number of rotor core sheets 22a can be set to nine. Therefore, in the rotor core sheet 22a having a non-circular shape such as an oval shape (two-way shape) in the present embodiment, the yield can be increased as compared with the rotor core sheet 22h having a circular plane shape.

Next, a modified example of the present embodiment will be described.

The rotor core sheet 22a of the first modification shown in FIG. 13 has a one-sided planar shape of the rotor core sheet 22a. That is, the rotor core sheet 22a has a shape in which a part of the circular rotor core sheet is linearly cut out, and has a one-sided shape in which a straight portion (non-arc-shaped portion) 22b is formed at a predetermined position. .. By stacking the rotor core sheets 22a shown in FIG. 13 alternately so that the straight portions 22b do not overlap in the circumferential direction to form the rotor core 22, the rotor core sheet 22a having the two-way shape of the embodiment is brushless. It is possible to reduce the weight and material cost of the brushless motor 21 while maintaining the characteristics of the motor 21.

Further, by forming the one-sided rotor core sheet 22a with an iron-based metal, the strength of the rotor core 22 can be increased as compared with the case where the rotor core sheet 22a is formed of a resin. Further, even in the case of the one-sided rotor core sheet 22a, the number of rotor core sheets 22a that can be obtained from the base material 34 can be increased, and the yield of the rotor core sheet 22a can be increased.

Further, the rotor core sheet 22a of the second modification shown in FIG. 14 is a convex rotor core sheet 22a in which a convex portion (non-arc-shaped portion) 22 g protruding outward is formed at a predetermined position of the circular rotor core sheet. It has become. Further, the rotor core sheet 22a of the third modification shown in FIG. 15 is a rotor core sheet having a convex shape on both sides, in which 22 g of convex portions (non-arc-shaped portions) protruding outward are formed at two contradictory points of the circular rotor core sheet. It is 22a. Also in the rotor core sheets 22a shown in FIGS. 14 and 15, the rotor core sheets 22a are alternately laminated so that the convex portions 22g do not overlap in the circumferential direction to form the rotor core 22, and the respective rotor core sheets 22a are formed. By forming the brushless motor 21 with a resin, it is possible to reduce the weight and material cost of the brushless motor 21 while maintaining the characteristics of the brushless motor 21.

Further, in the rotor core structure of the fourth modification shown in FIG. 16, in the elliptical (two-way shape) rotor core sheet 22a, the linear portions 22b of the rotor core sheets 22a adjacent to each other in the stacking direction of the plurality of rotor core sheets 22a are formed. The rotor core sheets 22a are alternately laminated by changing the orientation of the rotor core sheets 22a in the circumferential direction for each sheet so that the formed angle is 120 ° (R = 120 °). That is, as shown in FIGS. 17 and 18, the rotor core 22 has a circumference of the shaft 27 so that the angle formed by the straight portions 22b between the rotor core sheets 22a adjacent to each other in the stacking direction is 120 ° (R = 120 °). The rotor core sheets 22a are laminated in a staggered manner by changing the orientation of the rotor core sheets 22a one by one.

Even in the rotor core structure of the fourth modification, the weight balance during rotation of the rotor core 22 can be well maintained as in the case where the orientation of the rotor core sheet 22a is changed by 90 ° in the circumferential direction. Therefore, similarly to the case where the orientation of the rotor core sheet 22a is changed by 90 °, the weight of the brushless motor 21 can be reduced and the material cost can be reduced while maintaining the characteristics of the brushless motor 21. Further, by forming the rotor core sheet 22a with an iron-based metal, the strength of the rotor core 22 can be increased as compared with the case where the rotor core sheet 22a is formed of a resin. Further, the number of rotor core sheets 22a that can be obtained from the base material 34 can be increased, and the yield of the rotor core sheet 22a can be increased.

It goes without saying that the present invention is not limited to the above embodiment and can be variously modified without departing from the gist thereof. For example, in the above embodiment, the case where the cross-sectional shape of the stator 29 of the brushless motor 21 incorporated in the sunroof motor device 20 is substantially hexagonal has been taken up, but the cross-sectional shape of the stator 29 may be circular. ..

Further, in the above embodiment, the case where the angles formed by the non-arc-shaped portions (straight line portions 22b) between the rotor core sheets 22a adjacent to each other in the stacking direction of the plurality of rotor core sheets 22a are 90 ° and 120 ° has been described. The angle may be an angle other than 90 ° or 120 ° as long as the weight balance during rotation of the rotor core 22 can be well maintained.

Further, in the above embodiment, the case where the brushless motor 21 is mounted on the sunroof motor device 20 has been described, but the brushless motor 21 may be a motor for driving a power window or the like.

10: Sun roof device, 11: Roof panel, 12: Vehicle, 13: Roof, 14: Opening, 15a, 15b: Shoe, 16: Guide rail, 17a, 17b: Drive cable, 18: Front glass, 19: Adhesive , 20: Sun roof motor device, 21: Brushless motor, 22: Rotor core, 22a: Rotor core sheet (plate-shaped member), 22b: Straight part (non-arc-shaped part), 22c: Arc-shaped part, 22d: End part, 22e : Through hole, 22f: Space part, 22g: Convex part (non-arc-shaped part), 22h: Rotor core sheet, 22i: Sheet center part, 23: Magnet, 23a: Outer peripheral surface, 23b: Magnetic flux, 24: Rotor, 25: Stator core, 26: Rotor core unit, 27: Shaft, 28: Coil (winding), 29: Stator, 30: Teeth, 31: Rotating axis, 32: Terminal, 33: Insulation film, 34: Base material, 40: Gear part , 41: gear case, 41a: worm wheel housing, 42: worm wheel, 42a: teeth, 42b: output gear, 43: worm shaft, 43a: worm, 44: ball bearing

Claims (5)

A brushless motor comprising a stator core and a stator having windings wound around the stator core, and a rotor core and a rotor having a ring-shaped magnet provided on the outer circumference of the rotor core.
The stator core has a plurality of teeth extending radially inward of the stator core.
The rotor is rotatably arranged inside the plurality of teeth.
The magnet is magnetized so that a magnetic pole is formed on the outer peripheral portion of the magnet facing each of the plurality of teeth.
The rotor core is composed of a plurality of plate-shaped members formed in a non-circular shape having an arc-shaped portion and a non-arc-shaped portion in a planar shape.
The brushless motor is characterized in that the plurality of plate-shaped members are alternately laminated so that the non-arc-shaped portions of the plate-shaped members adjacent to each other in the stacking direction do not overlap in the circumferential direction of the magnet. The non-arc-shaped portion is a straight portion and is a straight portion.
The planar shape of each of the plurality of plate-shaped members is characterized in that it is an oval shape composed of a pair of the straight portions and a pair of arcuate portions connected to the respective ends of the pair of straight portions. The brushless motor according to claim 1. 2. The brushless motor described. The brushless motor according to any one of claims 1 to 3, wherein the plurality of plate-shaped members are made of an iron-based metal. Each of the plurality of plate-shaped members has an end portion including the arc-shaped portion.
The magnet is fixed to the rotor core with an adhesive and is fixed to the rotor core.
The one according to any one of claims 1 to 4, wherein the adhesive is filled in a space between the end portions adjacent to each other in the stacking direction of the plurality of plate-shaped members. Brushless motor.

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