JP2021145419A - Brushless motor - Google Patents

Abstract

To optimize flow of magnetic fluxes in a rotor core.SOLUTION: There is disclosed a brushless motor, in which a core member of a rotor comprises: an annular part arranged outside in a circumferential direction of a rotational axis; an outer peripheral core part which supports a plurality of magnets; and a plurality of bridges provided between the annular part and the outer peripheral core part outside in a radial direction of the rotational axis, the outer peripheral core part is supported by the plurality of bridges inside in the radial direction, the plurality of bridges comprise one or more first bridges provided within a first range in an axial direction of the rotational axis, and one or more second bridges provided within a second range different from the first range in the axial direction of the rotational axis, the one or more first bridges connect the outer peripheral core part with the annular part adjacent to the one or more first magnets, and the one or more second bridges connect the outer peripheral core part with the annular part adjacent to the one or more second magnets among the plurality of magnets from the annular part.SELECTED DRAWING: Figure 2A

Description

The present invention relates to a brushless motor including a rotor.

A brushless motor including a plurality of magnets arranged in the circumferential direction about the rotation axis and a rotor core holding these magnets is known (see Patent Document 1). The rotor core of this brushless motor includes an outer core portion that supports a magnet, an inner core portion that is rotatably attached to a rotating shaft, and a connecting portion that connects the outer core portion and the inner core portion.

Japanese Unexamined Patent Publication No. 2015-177721

When connecting between the outer core part and the inner core part by the connecting part, the magnetic flux from the magnet that originally wants to flow to the outside of the rotor core also flows to the inside (the side of the rotating shaft) through the connecting part. It ends up. In particular, magnetic flux leakage occurs between magnets adjacent to each other in the circumferential direction via the connecting portion and the inner core portion. Therefore, the magnetic flux flowing to the outside of the rotor core is reduced, which may lead to a decrease in the output of the motor.

The present invention has been made to solve the above problems, and an object of the present invention is to optimize the flow of magnetic flux in the rotor core.

In order to solve the above problem, one aspect of the present invention is a brushless motor including a rotor.
The rotor
Rotation axis and
The core member fixed to the rotating shaft and
It has a plurality of magnets arranged radially in the core member, and has.
The core member includes an annular portion arranged on the outer side in the circumferential direction of the rotating shaft, an outer peripheral core portion for supporting the plurality of magnets, and the annular portion and the outer peripheral portion on the outer side in the radial direction of the rotating shaft. It has a plurality of bridges provided between the core part and
The outer peripheral core portion is supported by the plurality of bridges inside the radial direction.
The plurality of bridges are provided in one or more first bridges provided in the first range in the axial direction of the rotation axis and in a second range different from the first range in the axial direction of the rotation axis. Includes one or more second bridges
The one or more first bridges connect the outer peripheral core portion adjacent to the one or more first magnets of the plurality of magnets and the annular portion.
The one or more second bridges include the outer peripheral core portion and the outer peripheral core portion adjacent to one or more second magnets different from the one or more first magnets among the plurality of magnets from the annular portion. Provided is a brushless motor connected to an annular portion.

According to the present invention, it is possible to optimize the flow of magnetic flux in the rotor core.

It is an exploded perspective view which shows the structure of the brushless motor of this Example. It is a top view of the rotor which constitutes the brushless motor of this Example. It is a perspective view which shows the structure of a rotor. It is a perspective view which shows the structure of a rotor. It is an enlarged perspective view which shows a part of a rotor. It is an enlarged perspective view which shows a part of a rotor. It is a top view which shows the magnetic flux of a magnet. It is a top view which shows the magnetic flux of a magnet.

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

FIG. 1 is an exploded perspective view showing the configuration of the brushless motor of this embodiment. In addition, in FIG. 1, the rotor 10 is shown very schematically, and the detailed configuration of the rotor 10 is shown in FIGS. 2 and later.

The brushless motor 1 of this embodiment is, for example, a three-phase brushless motor of U phase, V phase, and W phase. The brushless motor 1 is an inner rotor type that includes a rotor 10 and a stator 40, and the rotor 10 is arranged inside the stator 40.

The rotor 10 and the stator 40 are housed in a housing (not shown). The stator 40 is fixed via a housing, and the rotor 10 is rotatably supported around a rotation shaft 11 via the housing. In the following description, the radial direction, the circumferential direction, the inside, and the outside are defined with the axis of the rotating shaft 11 as the center.

The stator 40 includes a stator core 41 and a coil 42. The stator core 41 is configured by, for example, laminating electromagnetic steel sheets. The stator core 41 includes a back yoke portion 43 and a plurality of teeth portions 44 (12 in FIG. 1).

The plurality of tooth portions 44 project radially inward from positions at equal intervals in the circumferential direction on the inner peripheral surface of the back yoke portion 43. The plurality of tooth portions 44 form a dovetail groove-shaped slot 45 between each of the two tooth portions 44, 44 adjacent to each other in the circumferential direction. The teeth portion 44 includes an insulator 46 that is mounted so as to cover the surface. The insulator 46 is formed of an insulating material such as resin.

The coil 42 is attached to each of the plurality of teeth portions 44 from above the insulator 46 by, for example, centralized winding. The coils 42 arranged in the plurality of (12 in FIG. 1) slots 45 are connected to a three-phase (U-phase, V-phase, and W-phase) structure.

2A and 2B are plan views of the rotor constituting the brushless motor of the present embodiment, FIGS. 2A to 2B are perspective views showing the configuration of the rotor, and FIGS. 2C to 2D are enlarged perspective views showing a part of the rotor. 3 and 3A are plan views showing the magnetic fluxes of the magnets 12 (first magnet 12A and second magnet 12B).

As shown in FIGS. 2 to 2D, the rotors 10 constituting the brushless motor according to the present invention radiate at equal angles (36 ° in FIGS. 2 to 2D) around the rotation shaft 11 and the rotation shaft. It has a plurality of (10 in FIGS. 2D and 2D) magnets 12 to be arranged, and a core member 3 that supports the magnets 12.

The magnet 12 has a rectangular parallelepiped shape, and is arranged radially in the core member 3 so that one plane thereof faces the rotation shaft 11. The magnet 12 is magnetized in the circumferential direction and is arranged so that the directions of the magnetic poles are alternately reversed in the circumferential direction. That is, the north pole and the north pole or the south pole and the south pole of the magnets 12 adjacent to each other in the circumferential direction face each other (FIGS. 3 and 3A).

The magnet 12 includes a first magnet 12A and a second magnet 12B according to the direction of the magnetic poles thereof. As described above, in the example shown in FIGS. 2D and 2D, the first magnet 12A and the second magnet 12B are alternately arranged in the circumferential direction. Therefore, the directions of the magnetic poles in the circumferential direction of all (five) first magnets 12A are the same. Further, the directions of the magnetic poles in the circumferential direction of all (five) second magnets 12B are the same. However, the magnetic poles of the first magnet 12A in the circumferential direction and the magnetic poles of the second magnet 12B in the circumferential direction are reversed from each other.

The core member 3 is formed by laminating electromagnetic steel sheets in the axial direction of the rotating shaft 11. Each electrical steel sheet is formed by a press with high processing accuracy, and its shape is defined with high accuracy.

The core member 3 includes an annular portion 31 attached to the outer periphery of the rotating shaft 11, an outer peripheral core portion 32 that supports a plurality of magnets 12, and an annular portion 31 and an outer peripheral core portion 32 in the radial direction with respect to the rotating shaft 11. It has a plurality of bridges 33 formed between the bridges 33. The outer peripheral core portion 32 is supported by a plurality of bridges 33 on the inner side in the radial direction with respect to the rotation shaft 11.

The plurality of bridges 33 include one or more (five in FIGS. 2D and 2D) first bridges 33A extending in the first range A1 in the axial direction of the rotating shaft 11, and the first bridge 33A in the axial direction of the rotating shaft 11. It includes one or more (five in FIGS. 2D and 2D) second bridges 33B extending in a second range A2 different from the first range A1.

The first bridge 33A extends radially from the annular portion 31 toward the first magnet 12A with respect to the rotating shaft 11, and faces the first magnet 12A from the inside in the radial direction.

The second bridge 33B extends radially from the annular portion 31 toward the second magnet 12B with respect to the rotating shaft 11, and faces the second magnet 12B from the inside in the radial direction.

As shown in FIGS. 2D and 2D, the first bridge 33A is formed with a width of 1/2 of the total length of the core member 3 in the axial direction of the rotating shaft 11. That is, in FIG. 2A, the first bridge 33A is formed in the first range A1 which is the front half of the total length of the core member 3 in the axial direction of the rotating shaft 11. Further, in FIG. 2A, the second bridge 33B is formed in the second range A2, which is the inner half of the total length of the core member 3 in the axial direction of the rotating shaft 11 (see also FIG. 2B).

The outer peripheral core portion 32 is provided with an engaging portion 32a that engages with the first magnet 12A from the inner peripheral side and an engaging portion 32b that engages with the second magnet 12B from the inner peripheral side. The engaging portion 32a is formed in the first range A1 in which the first bridge 33A is formed in the axial direction of the rotating shaft 11. Further, the engaging portion 32b is formed in the second range A2 in which the second bridge 33B is formed in the axial direction of the rotating shaft 11.

The first bridge 33A is connected to the engaging portion 32a from the inner peripheral side, and the second bridge 33B is connected to the engaging portion 32b from the inner peripheral side.

Further, the outer peripheral core portion 32 is provided with an engaging portion 32c (an example of an engaging portion) that engages with the first magnet 12A and the second magnet 12B from the outer peripheral side.

In this embodiment, the magnet 12 (first magnet 12A and second magnet 12B) is mounted by the bridge 33 (first bridge 33A and second bridge 33B) from the inner peripheral side via the engaging portion 32a and the engaging portion 32b. I support it. Therefore, the magnet 12 (first magnet 12A and second magnet 12B) is prevented from falling off to the inner peripheral side. Further, the magnet 12 (first magnet 12A and second magnet 12B) is supported from the outer peripheral side via the engaging portion 32c. Therefore, the magnet 12 (first magnet 12A and second magnet 12B) is prevented from falling off to the outer peripheral side.

Further, the first magnet 12A is supported by the outer peripheral core portion 32 in the radial direction and the circumferential direction so as to be sandwiched between the engaging portion 32a on the inner peripheral side and the engaging portion 32c on the outer peripheral side. The second magnet 12B is supported by the outer peripheral core portion 32 in the radial direction and the circumferential direction so as to be sandwiched between the engaging portion 32b on the inner peripheral side and the engaging portion 32c on the outer peripheral side. Therefore, the positions of the magnets 12 (first magnet 12A and second magnet 12B) can be defined with high accuracy corresponding to the shape of the electromagnetic steel sheet formed by the press.

Further, the first bridge 33A and the second bridge 33B are formed with a width of 1/2 of the total length of the core member 3 in the axial direction of the rotating shaft 11. Therefore, as will be described later, the magnetic flux passing through the first bridge 33A or the second bridge 33B can be reduced as compared with the case where the bridge is formed over the entire core member 3 in the axial direction of the rotating shaft 11.

Next, the magnetic flux of the magnet 12 (first magnet 12A and second magnet 12B) will be described.

As shown in FIGS. 3 and 3A, the first magnet 12A and the second magnet 12B have a magnetic flux 100 (FIG. 3) toward the outer periphery of the first magnet 12A and the second magnet 12B, and the first bridge 33A or the first bridge 33A or the second magnet 12B. It forms a magnetic flux 200 (FIG. 3A) that leaks inward via the two bridges 33B. As shown in FIG. 3A, the magnetic flux 200 is formed so as to pass through the engaging portion 32a or the engaging portion 32b in the circumferential direction.

Since the magnetic flux 100 acts on the stator core 41 via the teeth portion 44, it contributes to the torque of the brushless motor 1. On the other hand, the magnetic flux 200 does not contribute to the torque, and the magnetic flux 100 is reduced by the amount of the magnetic flux 200.

In this embodiment, the first bridge 33A and the second bridge 33B are formed at positions corresponding to the first magnet 12A and the second magnet 12B in the circumferential direction, respectively. That is, the first bridge 33A and the second bridge 33B are located between the north and south poles of the first magnet 12A and the second magnet 12B, respectively. Therefore, it is possible to suppress the magnetic flux leaking between the first magnet 12A and the second magnet 12B that are adjacent to each other in the circumferential direction. That is, it is possible to substantially avoid leakage of the magnetic flux to the path 300 (FIG. 3A) via the first bridge 33A, the second bridge 33B, and the annular portion 31.

Further, as described above, in this embodiment, the first bridge 33A and the second bridge 33B are formed with a width of 1/2 of the total length of the core member 3 in the axial direction of the rotating shaft 11. Therefore, in this embodiment, as compared with the case where the first bridge 33A and the second bridge 33B (engaging portion 32a and engaging portion 32b) are formed over the entire length of the core member 3 in the axial direction of the rotating shaft 11. , The cross-sectional area of the path of the magnetic flux 200 extending in the circumferential direction can be reduced to about 1/2. Therefore, the generation of the magnetic flux 200 can be suppressed and the magnetic flux 100 can be increased, so that the torque of the brushless motor 1 can be improved.

Further, the first bridge 33A and the second bridge 33B (engaging portion 32a and engaging portion 32b) are alternately arranged in the circumferential direction, and the core member 3 is divided into two in the axial direction of the rotating shaft 11. , Has symmetry with the axial center of the rotating shaft 11 in the core member 3 as a boundary. Therefore, the magnetic and weight balance of the rotor 10 is ensured in both the circumferential direction and the axial direction of the rotating shaft 11. Such a good balance contributes to torque stability and the like.

The core member 3 in this embodiment includes an electromagnetic steel sheet (an example of a first plate material) having a bridge forming portion for forming the first bridge 33A with the center of the core member 3 as a boundary in the axial direction of the rotating shaft 11. It can be configured by laminating an electromagnetic steel plate (an example of a second plate material) having a bridge forming portion for forming the two bridges 33B. The bridge forming portion for forming the first bridge 33A refers to a portion of the first bridge 33A corresponding to one laminated steel plate. The same applies to the bridge forming portion for forming the second bridge 33B.

In this embodiment, each shape of the core member 3 divided into two in the axial direction of the rotating shaft 11 is a shape that is rotationally symmetric around the rotating shaft 11. Therefore, with the center of the rotating shaft 11 in the axial direction as a boundary, an electromagnetic steel sheet having the same shape (an example of the first plate material) has a specified angle, and an electromagnetic steel sheet having the same shape has a constant angle (an example) from the above specified angle. For example, the core member 3 can be formed by laminating a material shifted by 36 °) (an example of a second plate material). As described above, in this embodiment, by changing the angle of the electromagnetic steel plate having the same shape, it is possible to obtain two different cross-sectional shapes on the fixed coordinates in the cross section perpendicular to the axial direction of the rotating shaft 11, and the component. An efficient configuration can be realized from the viewpoint of points.

Although the examples of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to the examples, and the design and the like within a range not deviating from the gist of the present invention are also included.

For example, one or more first bridges 33A extending in the direction of the rotating shaft 11 in the first range A1 and one or more extending in the direction of the rotating shaft 11 in a second range A2 different from the first range A1. In addition to the second bridge 33B of the above, another bridge extending in a range different from the first range A1 and the second range A2 in the direction of the rotation axis 11 may be provided. That is, if the first range A1 and the second range A2 are divided into two, the magnets 12 may be divided into three or more ranges and different magnets 12 may be handled in each range.

Further, in the above-described embodiment, as a preferable example, all the electromagnetic steel sheets in the first range A1 form only the first bridge 33A, and all the electrical steel sheets in the second range A2 form only the second bridge 33B. Is formed, but is not limited to this. For example, some electrical steel sheets in the first range A1 may form the second bridge 33B, or some electrical steel sheets in the second range A2 may form the first bridge 33A.

Further, in the above-described embodiment, the outer peripheral core portion 32 is continuous via the bridge 33 on the inner side in the radial direction, and is separated by sandwiching the magnet 12 on the outer side in the radial direction. However, the engaging portion 32c may be formed in a continuous manner over the entire circumference. That is, the outer side of the magnet 12 in the radial direction may be covered with the engaging portion 32c.

The following additional notes will be further disclosed with respect to the above examples of the present invention.

(Appendix 1)
A brushless motor (1) including a rotor (10).
The rotor
Rotation axis (11) and
The core member (3) fixed to the rotating shaft and
It has a plurality of magnets (12) radially arranged in the core member, and has a plurality of magnets (12).
The core member includes an annular portion (31) arranged outside the rotation axis in the circumferential direction, an outer peripheral core portion (32) that supports the plurality of magnets, and the outside outside the rotation axis in the radial direction. It has a plurality of bridges (33) provided between the annular portion and the outer peripheral core portion, and has a plurality of bridges (33).
The outer peripheral core portion is supported by the plurality of bridges inside the radial direction.
The plurality of bridges include one or more first bridges (33A) provided in the first range (A1) in the axial direction of the rotating shaft, and a first bridge (33A) different from the first range in the axial direction of the rotating shaft. Includes one or more second bridges (33B) provided in two ranges (A2).
The one or more first bridges connect the outer peripheral core portion and the annular portion adjacent to one or more first magnets (12A) of the plurality of magnets.
The one or more second bridges are the outer peripheral cores adjacent to one or more second magnets (12B) different from the one or more first magnets among the plurality of magnets from the annular portion. A brushless motor that connects a portion and the annular portion.

According to the configuration of Appendix 1, one or more first bridges extending in the first range in the direction of the rotation axis and one or more extending in the second range different from the first range in the direction of the rotation axis. Since the magnet is supported on the inner side in the radial direction by the second bridge, the magnetic flux of the magnet passing through the first bridge or the second bridge can be reduced while preventing the magnet from falling off inward. Therefore, the flow of magnetic flux can be optimized, and for example, the magnetic flux that contributes to torque can be increased.

In the brushless motor described in Appendix 1, one or more first bridges may be provided only in the first range, or one or more second bridges may be provided only in the second range. You may. Further, one or more first bridges may be provided in a part of the second range in addition to the first range, and in this case, one or more second bridges may be provided in addition to the second range. It may be provided in the entire first range. Alternatively, conversely, one or more first bridges may be provided over the entire second range in addition to the first range, in which case one or more second bridges may be added to the second range. It may be provided in a part of the first range.

According to the configuration of Appendix 2, since the substantial cross-sectional area of the first bridge and the second bridge in the radial direction can be reduced, the magnetic flux of the magnet passing through the first bridge or the second bridge can be reduced. ..

(Appendix 2)
In the brushless motor described in Appendix 1,
A brushless motor in which the first range is located on one side in the axial direction of the rotating shaft and the second range is located on the other side in the axial direction of the rotating shaft.

According to the configuration of Appendix 2, since the bridges are unevenly distributed on one side and the other side in the direction of the rotation axis, the magnetic and weight balance of the core member can be ensured.

(Appendix 3)
In the brushless motor according to any one of Appendix 1 to Appendix 2,
The core member is formed by laminating a plurality of plate members in the axial direction of the rotation axis.
Each of the plurality of plate materials has a bridge forming portion in the circumferential direction in a number smaller than the number of the magnets.
The plurality of plate materials include one or more first plate materials arranged such that the bridge forming portion forms the one or more first bridges, and the bridge forming portion forming the one or more second bridges. Includes one or more second plates arranged to form
A brushless motor in which the first bridge is composed of only the first plate material, and the second bridge is composed of only the second plate material.

According to the configuration of Appendix 3, the core member can be configured by laminating the first plate material having the first bridge forming portion and the second plate material having the second shape having the second bridge forming portion. ..

(Appendix 4)
In the brushless motor according to any one of Appendix 1 to Appendix 3,
The one or more first bridges are arranged one by one at predetermined angular intervals around the rotation axis.
A brushless motor in which the one or more second bridges are arranged one by one at the predetermined angular interval around the rotation axis.

According to the configuration of Appendix 4, since the first bridge and the second bridge are arranged one by one at predetermined angular intervals, the magnetic and weight balance of the core member can be ensured. In addition to the first bridge and the second bridge, bridges other than the first bridge and the second bridge, which are arranged one by one at predetermined angular intervals, may be provided.

(Appendix 5)
In the brushless motor described in Appendix 4,
The plurality of magnets are composed of the one or more first magnets and the one or more second magnets.
A brushless motor in which the first bridge and the second bridge are alternately arranged in the circumferential direction when viewed in the axial direction of the rotation axis.

According to the configuration of Appendix 5, since the first bridge and the second bridge are evenly arranged in the circumferential direction and the rotation axis direction, the magnetic and weight balance of the core member can be further improved.

(Appendix 6)
In the brushless motor according to any one of Supplementary Note 1 to Supplementary Note 5,
The core member is a brushless motor having an engaging portion (32c) that engages each of the plurality of magnets from the outer peripheral side in the radial direction.

According to the configuration of Appendix 7, the magnet is prevented from falling off to the outer peripheral side due to the engagement with the engaging portion.

1 Brushless motor 3 Core member 10 Rotor 11 Rotating shaft 12 Magnet 12A 1st magnet 12B 2nd magnet 31 Circular portion 32 Outer core portion 33 Bridge 33A 1st bridge 33B 2nd bridge

Claims (6)

A brushless motor with a rotor
The rotor
Rotation axis and
The core member fixed to the rotating shaft and
It has a plurality of magnets arranged radially in the core member, and has.
The core member includes an annular portion arranged on the outer side in the circumferential direction of the rotating shaft, an outer peripheral core portion for supporting the plurality of magnets, and the annular portion and the outer peripheral portion on the outer side in the radial direction of the rotating shaft. It has a plurality of bridges provided between the core part and
The outer peripheral core portion is supported by the plurality of bridges inside the radial direction.
The plurality of bridges are provided in one or more first bridges provided in the first range in the axial direction of the rotation axis and in a second range different from the first range in the axial direction of the rotation axis. Includes one or more second bridges
The one or more first bridges connect the outer peripheral core portion adjacent to the one or more first magnets of the plurality of magnets and the annular portion.
The one or more second bridges include the outer peripheral core portion and the outer peripheral core portion adjacent to one or more second magnets different from the one or more first magnets among the plurality of magnets from the annular portion. A brushless motor that connects to the annular part. In the brushless motor according to claim 1,
A brushless motor in which the first range is located on one side in the axial direction of the rotating shaft and the second range is located on the other side in the axial direction of the rotating shaft. In the brushless motor according to claim 1 or 2.
The core member is formed by laminating a plurality of plate members in the axial direction of the rotation axis.
Each of the plurality of plate materials has a bridge forming portion in the circumferential direction in a number smaller than the number of the magnets.
The plurality of plate materials include one or more first plate materials arranged such that the bridge forming portion forms the one or more first bridges, and the bridge forming portion forming the one or more second bridges. Includes one or more second plates arranged to form
A brushless motor in which the first bridge is composed of only the first plate material, and the second bridge is composed of only the second plate material. The brushless motor according to any one of claims 1 to 3.
The one or more first bridges are arranged one by one at predetermined angular intervals around the rotation axis.
A brushless motor in which the one or more second bridges are arranged one by one at the predetermined angular interval around the rotation axis. In the brushless motor according to claim 4,
The plurality of magnets are composed of the one or more first magnets and the one or more second magnets.
A brushless motor in which the first bridge and the second bridge are alternately arranged in the circumferential direction when viewed in the axial direction of the rotation axis. The brushless motor according to any one of claims 1 to 5.
The core member is a brushless motor having an engaging portion that engages each of the plurality of magnets from the outer peripheral side in the radial direction.

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