阅读说明：本技术 马达的转子及其制造方法 (Rotor of motor and manufacturing method thereof ) 是由 杉胁皓介 于 2021-05-10 设计创作，主要内容包括：本发明提供马达的转子及其制造方法。马达的转子具有：旋转轴；以及磁铁,其固定于所述旋转轴,所述旋转轴在远离所述磁铁的位置具有切口部,该切口部划定与所述旋转轴的轴心垂直的截面形状相对于所述轴心非对称的非对称截面,所述磁铁形成有沿所述轴心的方向延伸的贯通孔和非贯通孔,以使所述磁铁的重心相对于所述轴心位于形成有所述切口部的一侧的方式设定所述贯通孔和非贯通孔。(The invention provides a rotor of a motor and a manufacturing method thereof. The rotor of the motor has: a rotating shaft; and a magnet fixed to the rotating shaft, the rotating shaft having a notch defining an asymmetric cross section in which a cross-sectional shape perpendicular to an axis of the rotating shaft is asymmetric with respect to the axis, the magnet being formed with a through hole and a non-through hole extending in a direction of the axis, the through hole and the non-through hole being set such that a center of gravity of the magnet is located on a side of the axis where the notch is formed.)

1. A rotor of a motor, comprising:

a rotating shaft; and

a magnet fixed to the rotating shaft,

the rotating shaft has a notch portion defining an asymmetric cross section in which a cross-sectional shape perpendicular to an axis of the rotating shaft is asymmetric with respect to the axis at a position away from the magnet,

the magnet is formed with a through hole and a non-through hole extending in the direction of the axis,

the through-hole and the non-through-hole are set so that the center of gravity of the magnet is located on the side where the notch is formed with respect to the axis.

2. The rotor of a motor according to claim 1,

the through hole is formed on the side of the cutout portion with respect to the shaft center when viewed from the direction of the shaft center,

the non-through hole is formed on the opposite side of the notch portion with respect to the shaft center when viewed from the direction of the shaft center,

the volume of the through-hole is smaller than the volume of the non-through-hole.

3. The rotor of a motor according to claim 1 or 2,

at least one of the through-hole and the non-through-hole has a tapered shape.

4. The rotor of a motor according to claim 1 or 2,

the magnet has:

a 1 st end surface perpendicular to the axis and located on a side opposite to the cutout portion; and

a 2 nd end surface perpendicular to the axis and located on the notch portion side,

the 1 st end surface is not provided with a projection at a position asymmetrical with respect to the axial center.

5. The rotor of a motor according to claim 4,

the 2 nd end surface is not provided with a projection at a position asymmetrical with respect to the axial center.

6. The rotor of a motor according to claim 1 or 2,

the magnet has a cylindrical outer peripheral side surface,

the outer peripheral side surface is symmetrical with respect to the axis when viewed from the direction of the axis.

7. A method of manufacturing a rotor of a motor according to claim 1 or 2,

the magnet is an integrally formed magnet,

the method for manufacturing the rotor of the motor includes a step of molding the magnet together with the rotating shaft by using a mold.

Technical Field

The present invention relates to a rotor of a motor and a method of manufacturing the same.

Background

Patent document 1 discloses a rotor of a motor including: a rotating shaft; a core member having a plurality of teeth radially formed thereon; and a winding unit in which a winding is wound around the grooves between the plurality of teeth. In patent document 1, a D-shaped cut portion is formed at the tip end of the rotating shaft, and the wire diameter, the number of turns, the winding method, and the like of the windings wound in the plurality of slots are different in order to eliminate the imbalance.

Patent document 1: japanese patent laid-open publication No. 2017-017941

As in patent document 1, it is necessary to perform winding work in consideration of the wire diameter, the number of turns, the winding method, and the like of the winding, and the work is complicated.

Disclosure of Invention

Accordingly, an object of the present invention is to provide a rotor of a motor having excellent workability and a method for manufacturing the same.

The above object can be achieved by a rotor of a motor having: a rotating shaft; and a magnet fixed to the rotating shaft, the rotating shaft having a notch defining an asymmetric cross section in which a cross-sectional shape perpendicular to an axis of the rotating shaft is asymmetric with respect to the axis, the magnet being formed with a through hole and a non-through hole extending in a direction of the axis, the through hole and the non-through hole being set such that a center of gravity of the magnet is located on a side of the axis where the notch is formed.

The above object is also achieved by a method for manufacturing a rotor of a motor, which is a method for manufacturing a rotor of a motor, wherein the magnet is an integrally molded magnet, and the method for manufacturing a rotor of a motor includes a step of molding the magnet together with the rotating shaft by a mold.

A rotor of a motor having excellent workability and a method for manufacturing the same can be provided.

Drawings

Fig. 1A and 1B are explanatory views of the rotor.

Fig. 2A and 2B are explanatory views of the rotor.

Fig. 3A and 3B are explanatory views of a method of manufacturing the rotor.

Detailed Description

Fig. 1A, 1B, 2A, and 2B are explanatory views of the rotor 1. Fig. 1B is a sectional view taken along line a-a of fig. 1A. Fig. 2B is a sectional view taken along line B-B of fig. 2A. The rotor 1 is used for an inner rotor type motor, and includes a rotary shaft 10 and a magnet 20. The rotary shaft 10 and the magnet 20 are integrally formed with each other. The rotating shaft 10 is made of, for example, metal, but is not limited thereto. The rotary shaft 10 has a base end portion 11 and a tip end portion 12. The distal end portion 12 side corresponds to an output side for transmitting the rotational power of the motor to the outside. The distal end portion 12 is formed with a notch portion 13, and the notch portion 13 is a D-shaped notch portion defining an asymmetrical cross section having an asymmetrical cross section shape with respect to the axial center a. Fig. 1B shows the position of the center of gravity G1 of only the rotation axis 10. The position of the center of gravity G1 is shifted from the axis a toward the opposite side of the cutout portion 13 by the cutout portion 13. Fig. 1A is a view of the rotor 1 from the base end 11 side, and fig. 2A is a view of the rotor 1 from the tip end 12 side.

The magnet 20 is provided closer to the base end 11 than the tip end 12. The magnets 20 are made of plastic magnets in which magnetic powder is mixed with resin, and are alternately arranged in the circumferential direction with different polarities. The magnet 20 is an example of an integrally molded magnet, and may be a rubber magnet using rubber, for example. The magnet 20 is formed in a substantially disc shape having a predetermined thickness in the direction of the axis a. Specifically, the outer surface of the magnet 20 has an upper end surface 21, a lower end surface 22, and an outer peripheral side surface 23. The upper end surface 21 and the lower end surface 22 are respectively perpendicular to the axial center a and are circular. The upper end surface 21 and the lower end surface 22 are opposed to each other with a distance corresponding to the thickness of the magnet 20 in the direction of the axis a. The upper end surface 21 is an example of the 1 st end surface. The lower end surface 22 is an example of the 2 nd end surface. The outer peripheral side surface 23 is cylindrical. In other words, as shown in fig. 1A and 2A, the outer peripheral side surface 23 is symmetrical with respect to the axial center a, and for example, no portion is provided that protrudes radially outward from the outer peripheral side surface 23.

The lower end surface 22 is formed with a recess 24 having a predetermined depth. As shown in fig. 2A, the recess 24 has a substantially circular shape centered on the rotation shaft 10. In the magnet 20, a plurality of non-through holes 25, small-diameter through holes 26, and large-diameter through holes 27 are formed at substantially equal angular intervals on a predetermined circumference around the rotation axis 10. Thus, the magnet 20 is reduced in weight. The non-through hole 25, the small-diameter through hole 26, and the large-diameter through hole 27 extend from the bottom of the recess 24 toward the upper end face 21 in the direction of the axis a, and the small-diameter through hole 26 and the large-diameter through hole 27 penetrate the magnet 20 in the direction of the axis a, but the non-through hole 25 does not penetrate the magnet 20. That is, the non-through hole 25 does not extend to the upper end surface 21.

As shown in fig. 1A and 2A, the shape viewed from the direction of the axial center a of each of the non-through hole 25, the small-diameter through hole 26, and the large-diameter through hole 27 is an elongated hole shape extending in the circumferential direction of the magnet 20. As shown in fig. 1B and 2B, the non-through hole 25, the small-diameter through hole 26, and the large-diameter through hole 27 are each formed in a tapered shape whose inner diameter gradually decreases from the recess 24 side to the end face 21 side. The small-diameter through hole 26 is formed to have a smaller inner diameter than the large-diameter through hole 27. Specifically, as shown in fig. 1A and 2A, the small-diameter through hole 26 is shorter than the large-diameter through hole 27 with respect to the length of the magnet 20 in the circumferential direction, and the small-diameter through hole 26 is narrower than the large-diameter through hole 27 with respect to the width of the small-diameter through hole 26 in the radial direction of the magnet 20.

As shown in fig. 1A, two small-diameter through holes 26, two large-diameter through holes 27, two non-through holes 25, and two large-diameter through holes 27 are formed in the circumferential direction of the magnet 20. Two small-diameter through holes 26 are formed on the notch portion 13 side with respect to the axial center a. Two non-through holes 25 are formed on the opposite side of the axis a from the two small-diameter through holes 26. Fig. 1B shows the position of the center of gravity G2 of the magnet 20. The positions of the centers of gravity G2 are shifted toward the cutout portion 13 side with respect to the axial center a by the non-through holes 25, the small-diameter through holes 26, and the large-diameter through holes 27. The position of the center of gravity of the rotor 1 is adjusted to be on or near the axial center a depending on the position of the center of gravity G1 of the rotary shaft 10 and the position of the center of gravity G2 of the magnet 20.

As shown in fig. 1B and 2B, in magnet 20, when viewed in a direction perpendicular to axial center a, no protruding portion is provided that protrudes from an asymmetric position with respect to axial center a of upper end surface 21 or lower end surface 22. As shown in fig. 1A and 2A, the outer peripheral side surface 23 is not provided with a protruding portion protruding from a position asymmetrical with respect to the axis a when viewed from the direction of the axis a, and has a shape symmetrical with respect to the axis a. That is, the position of the center of gravity G2 is set so as to be balanced with respect to the center of gravity G1 of the rotary shaft 10 by the shape of the inside of the magnet 20 formed by the non-through hole 25, the small-diameter through hole 26, and the large-diameter through hole 27. Therefore, once a mold for manufacturing the magnet 20 is designed, the same magnet 20 can be manufactured in large quantities at low cost, and workability in manufacturing is excellent.

Further, since there is no need for work such as coating a balance weight at a position on the outer peripheral surface of the magnet 20 asymmetrical to the axial center a, the workability in manufacturing is also excellent from such a viewpoint. Further, since no portion is provided which protrudes from the upper end surface 21, the lower end surface 22, and the outer peripheral side surface 23, the operability is also excellent. Further, since the magnet 20 is formed with the plurality of non-through holes 25, the small-diameter through holes 26, and the large-diameter through holes 27, the surface area of the magnet 20 can be secured, and the heat dissipation performance can be improved.

Next, a method of manufacturing the rotor 1 will be explained. Fig. 3A and 3B are explanatory views of a method of manufacturing the rotor 1. The rotary shaft 10 prepared in advance is set in the fixed mold 40 and the movable mold 50. Specifically, the rotary shaft 10 is disposed in the holding hole 41 of the fixed mold 40, and the movable mold 50 is brought close to the fixed mold 40 so that the rotary shaft 10 is inserted into the insertion hole 52 of the movable mold 50. Here, the fixed die 40 is formed with an upper end face 42, a convex portion 44, a low projecting portion 45, and a small-diameter high projecting portion 46 corresponding to the lower end face 22, the concave portion 24, the non-through hole 25, and the small-diameter through hole 26 of the magnet 20, respectively. Although not shown in fig. 3A and 3B, a large-diameter and high-protrusion portion corresponding to the large-diameter through hole 27 of the magnet 20 is also formed. A lower end surface 51 corresponding to the upper end surface 21 of the magnet 20 is formed on the movable die 50. The movable die 50 is made to approach the fixed die 40 until the lower end face 51 of the movable die 50 comes into contact with the front end of the high projecting portion 46 of the fixed die 40.

Next, an annular magnetization magnet 60 is disposed around the space between the fixed mold 40 and the movable mold 50. The magnetizing magnets 60 are alternately arranged in different polarities in the circumferential direction. Next, the injection device is driven to inject molten resin containing magnetic powder into the cavity surrounded by the fixed mold 40, the movable mold 50, and the magnetization magnet 60. The injected dissolved resin is magnetized to different polarities alternately arranged in the circumferential direction by the magnetizing magnet 60 during the curing process. Thus, as shown in fig. 3A, the magnet 20 is molded using the rotary shaft 10 as an insert. After the dissolved resin is cured and the magnet 20 is molded, as shown in fig. 3B, the movable mold 50 is separated from the magnet 20, and the rotary shaft 10 is pulled out from the holding hole 41 of the fixed mold 40, whereby the rotor 1 can be manufactured. Here, the low protrusion 45 and the high protrusion 46 are tapered. Therefore, the magnet 20 can be easily separated from the fixed mold 40.

In the above embodiment, the D-cut is shown as an example of the asymmetrical cross section formed on the rotary shaft 10, but the present invention is not limited thereto. In the above embodiment, the non-through hole 25, the small-diameter through hole 26, and the large-diameter through hole 27 have a tapered shape in which the inner diameter gradually decreases from the lower end surface 22 side to the upper end surface 21 side. For example, the holes may have a tapered shape in which the inner diameter gradually decreases from the upper end surface 21 side to the lower end surface 22 side. In this case, the fixed mold and the movable mold may be arranged on the opposite side of the positional relationship between the fixed mold 40 and the movable mold 50 shown in fig. 3A.

Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the present invention described in the claims.