WO2024116245A1

WO2024116245A1 - Magnetization device for rotor, rotor, motor, and method for manufacturing rotor

Info

Publication number: WO2024116245A1
Application number: PCT/JP2022/043796
Authority: WO
Inventors: 淳一宮木; 冰潔石
Original assignee: ミネベアミツミ株式会社
Filing date: 2022-11-28
Publication date: 2024-06-06

Abstract

A magnetization device (10) for a rotor (20) comprises a plurality of electromagnets (500, 600) that are arrayed in the circumferential direction and that magnetize the rotor (20) having a rotor core (100) provided with a hole (310) and a magnet (200) stored in the hole (310) of the rotor core (100). The electromagnets (500, 600) are provided with magnetic bodies (510, 610) and coils (520, 620) wound on the magnetic bodies (510, 610). The winding axis direction of the coils (520, 620) is the axial direction of the rotor (20). Magnetic fluxes generated from the coils (520, 620) pass through the magnetic bodies (510, 610) toward the side surfaces (230, 240) of the magnet (200) in the circumferential direction of the rotor (20).

Description

Rotor magnetization device, rotor, motor, and rotor manufacturing method

The present invention relates to a rotor magnetization device, a rotor, a motor, and a method for manufacturing a rotor.

When two magnets are placed inside a rotor, such as an IPM rotor, so that they repel each other, a technique known as post-magnetization is known in which an unmagnetized magnet is placed in the rotor, and then the entire rotor is magnetized using a magnetizing device.

JP 2021-197748 A JP 2021-164402 A JP 2010-193587 A

In the post-magnetization process, it can be difficult to achieve a magnetization rate approaching 100%.

In one aspect, the objective is to provide a rotor magnetization device, rotor, motor, and rotor manufacturing method that can improve the magnetization rate.

In one embodiment, the rotor magnetization device includes a plurality of electromagnets arranged in a circumferential direction to magnetize a rotor having a rotor core with holes and magnets housed in the holes of the rotor core. The electromagnets include a magnetic body and a coil wound around the magnetic body. The winding axis of the coil is the axial direction of the rotor, and the magnetic flux generated from the coil passes through the magnetic body and is directed toward the side of the magnet in the circumferential direction of the rotor.

According to one aspect, the magnetization rate can be improved.

FIG. 1 is a side cross-sectional view showing an example of a motor according to an embodiment. FIG. 2 is a perspective view illustrating an example of a rotor according to the embodiment. FIG. 3 is an enlarged perspective view illustrating an example of a rotor according to the embodiment. FIG. 4 is a perspective view showing an example of a magnetized result of the magnet in the embodiment. FIG. 5 is a perspective view illustrating an example of a magnetizing device according to an embodiment. FIG. 6 is a perspective view illustrating an example of an outer magnetization step in the embodiment. FIG. 7 is a cross-sectional perspective view illustrating an example of an inner magnetization step in the embodiment. FIG. 8 is an enlarged perspective view illustrating an example of an inner magnetization step in the embodiment.

Below, embodiments of the rotor magnetization device, rotor, motor, and rotor manufacturing method disclosed in the present application are described in detail with reference to the drawings. Note that the dimensional relationships and ratios of each element in the drawings may differ from reality. There may also be parts in which the dimensional relationships and ratios differ between the drawings.

[Embodiment]
First, a motor 1 and a rotor 20 in this embodiment will be described with reference to Figs. 1 to 3. Fig. 1 is a side cross-sectional view showing an example of a motor in this embodiment. Fig. 2 is a perspective view showing an example of a rotor in this embodiment. Fig. 3 is an enlarged perspective view showing an example of a rotor. Fig. 3 is an enlarged view of a portion shown in frame F1 in Fig. 2.

As shown in FIG. 1, the motor 1 includes a rotor 20, a shaft 80, and a stator 90. The stator 90 includes a stator core 91, an insulator 92, and a coil 93. In the motor 1, the rotor 20 is rotatably supported on the shaft 80 via a bearing 81. The motor 1 is also housed in a housing 70. As shown in FIG. 1, the motor 1 in this embodiment is a so-called inner rotor type motor in which the stator 90 is positioned radially outward of the rotor 20.

The stator core 91 is formed by stacking multiple magnetic materials, such as stainless steel or magnetic steel plates, in the axial direction. The insulator 92 is formed from an insulating material, such as resin. The coil 93 is formed by winding a rectangular wire, made of a conductor, such as copper, around the stator core 91 via the insulator 92.

As shown in Figures 1 and 2, the rotor 20 includes a rotor core 100 and a magnet 200. The rotor core 100 is formed by stacking multiple flat cores made of, for example, electromagnetic steel sheets.

As shown in FIG. 3, the rotor core 100 of the rotor 20 includes a magnetic pole portion 110, an annular portion 120, and a connection portion 130.

The annular portion 120 is located radially inward. The connection portion 130 connects the annular portion 120 and the magnetic pole portion 110 in the radial direction. In the circumferential direction, there is a gap 330 between the magnetic pole portion 110 and the connection portion 130.

The magnetic pole portion 110 is located radially outside the annular portion 120. As shown in FIG. 4, the magnetic pole portion 110 has an extension portion 112 that extends radially toward the annular portion 120. FIG. 4 is a perspective view showing an example of the magnetization result of a magnet in an embodiment. The extension portion 112 is an example of a portion that extends toward the annular portion 120.

As shown in FIG. 4, the magnet 200 is sandwiched in the circumferential direction between the extensions 112 of the magnetic pole portions 110 of the rotor 20. Also, in FIG. 4, the shading of the fill in the magnet 200 indicates the magnitude of the magnetic force or magnetization rate of the magnet 200, with a darker shade meaning that the magnetic force or magnetization rate is relatively high and a lighter shade meaning that the magnetic force or magnetization rate is relatively low.

The extension 112 of the magnetic pole portion 110 of the rotor core 100 is in contact with the

side surface

230 or 240 of the radially outer portion 211 of the magnet 200, and the

side surface

230 or 240 of the radially inner portion 212 of the magnet 200 is exposed to the extension 112. As shown in FIG. 1, the magnetic pole portion 110 faces the stator 90 in the radial direction. A hole 310 is formed between two magnetic pole portions 110 adjacent in the circumferential direction. In this case, the extension 112 of the magnetic pole portion 110 forms the inner surface of the hole 310.

The magnet 200 may be, for example, a bonded magnet or a sintered magnet made of a mixture of magnetic powder and resin. The magnet 200 is placed in the hole 310 in an unmagnetized state. The magnet 200 may be filled into the hole 310 by, for example, heating the bonded magnet to a high temperature to make it fluid.

As shown in FIG. 4, the magnet 200 is formed in a generally rectangular parallelepiped shape and has a side surface 230 that contacts the extension portion 112 on one side in the circumferential direction of the rotor core 100, and a side surface 240 that contacts the extension portion 112 on the other side. Also, as shown in FIG. 4, the magnet 200 has a radially outer portion 211 that contacts the extension portion 112, and a radially inner portion 212 that protrudes from the extension portion 112 toward the annular portion 120.

In this embodiment, the radially outer portion 211 of the magnet 200 is evenly magnetized as shown in FIG. 4. Meanwhile, the radially inner portion 212 protruding toward the annular portion 120 of the magnet 200 has a first region 201 with a low magnetic force and a second region 202 and a third region 203 with a high magnetic force. In the axial direction, the first region 201 is between the second region 202 and the third region 203.

In this embodiment, the magnetization rate in the first region 201 is smaller than the magnetization rate in the radially outer portion 211 of the magnet 200. In this case, the magnetic force in the first region 201 is smaller than the magnetic force in the radially outer portion 211 of the magnet 200.

As shown in FIG. 3, the radially inner side surface 270 of the magnet 200 faces the annular portion 120 of the rotor core 100 through a gap 320. In this case, the gap 320 acts as a flux barrier, preventing magnetic flux from flowing radially inward from the side surface 270 of the magnet 200.

The magnet 200 is placed in the hole 310 before being magnetized, and is then magnetized by the magnetization device 10 shown in FIG. 5. FIG. 5 is a perspective view showing an example of a magnetization device in an embodiment. As shown in FIG. 5, the magnetization device 10 in an embodiment includes

multiple electromagnets

500 and 600 arranged in the circumferential direction. In the following, when multiple magnets 200 are to be distinguished from one another, they may be referred to as magnets 20a to 20j.

Electromagnets

500 and 600 are arranged radially inward of magnet 200, which is indicated by a dashed line in FIG. 5. Electromagnet 500 is located on the upper side of magnetization device 10 in the axial direction, and electromagnet 600 is located on the lower side of magnetization device 10 in the axial direction. In the following, when the multiple electromagnets 500 are to be individually expressed, they may be written as electromagnets 50a to 50j, and when the multiple electromagnets 600 are to be individually expressed, they may be written as electromagnets 60a to 60j. The multiple electromagnets 50a to 50j are supported by, for example, a ring-shaped frame (not shown).

The

electromagnets

500 and 600 include an upper coil 520 wound around an upper magnetic body 510 and a lower coil 620 wound around a lower magnetic body 610. The upper magnetic body 510 and the lower magnetic body 610 face each other in the axial direction of the rotor 20, either directly or via another member (magnetic body). In this case, the gap 330 of the rotor core 100 is located between the upper coil 520 and the lower coil 620 in the axial direction. As shown in FIG. 5, the winding axis direction of the upper coil 520 and the lower coil 620 is the axial direction of the rotor 20. Note that when the upper magnetic body 510 and the lower magnetic body 610 are expressed without distinction, they may be simply referred to as

magnetic bodies

510 and 610, and when the upper coil 520 and the lower coil 620 are expressed without distinction, they may be simply referred to as

coils

520 and 620.

The multiple electromagnets of the magnetization device 10 may also include an outer electromagnet 700 that is adjacent to the

electromagnets

500 and 600 in the radial direction. In this case, the

electromagnets

500 and 600 are disposed inside the outer electromagnet 700 in the radial direction. The outer electromagnet 700 faces the rotor core 100 in the radial direction.

The outer electromagnet 700 comprises an outer magnetic body 710 and an outer coil 720 wound around the outer magnetic body 710. The outer magnetic body 710 extends radially inward from, for example, an annular support portion 730. The outer magnetic body 710 faces the magnetic pole portion 110 of the rotor core 100 in the radial direction. The winding axis direction of the outer coil 720 is the radial direction of the rotor 20.

The manufacturing method of the rotor 20 using the magnetizing device 10 will be described with reference to Figures 6 to 8. Figure 6 is a perspective view showing an example of the outer magnetizing process in the embodiment. Figure 7 is a cross-sectional perspective view showing an example of the inner magnetizing process in the embodiment. Figure 8 is an enlarged perspective view showing an example of the inner magnetizing process in the embodiment. Figure 7 shows a cross section taken along plane S1 in Figure 5. The manufacturing method in this embodiment includes a magnetizing process in which the side surfaces 230, 240 of the magnet 200 housed in the hole 310 of the rotor core 100 are magnetized in the circumferential direction of the rotor 20.

The magnetization process may also include a process of contacting the

magnetic bodies

510 and 610 with the side surfaces 250 and 260 of the magnet 200. Specifically, as shown in FIG. 8, the

magnetic bodies

51a and 51j contact the side surface 250 of the radially inner portion 212 of the magnet 200, and the

magnetic bodies

61a and 61j contact the side surface 260 of the radially inner portion 212 of the magnet 200.

Also, as shown in FIG. 7, in the magnetization process, a yoke 400 may be further disposed in the gap 330 of the rotor core 100. In this embodiment, the yoke 400 constitutes a part of the

electromagnets

500 and 600. In the following, when the yokes 400 are to be distinguished from one another, they may be referred to as yokes 4a1, 4b2, etc.

The yoke 400 is formed of a material with high magnetic permeability, such as iron. The yoke 400 has a shape that is substantially the same as the gap 330 of the rotor core 100. In the embodiment, the magnet 200 contacts two yokes 400 in the circumferential direction. For example, as shown in FIG. 6, the magnet 20a contacts two yokes 4a1 and 4a2, and the magnet 20b contacts two yokes 4b1 and 4b2.

In the embodiment, the

magnetic bodies

510 and 610 contact multiple yokes 400. For example, as shown in FIG. 6, the magnetic body 51a contacts two yokes 4a2 and 4b1.

Currents are passed through adjacent electromagnets in the circumferential direction so that the polarities are opposite to each other. For example, if the portion of electromagnet 50j shown in FIG. 6 that contacts magnet 200 is a north pole, then the portion of electromagnet 50a adjacent to electromagnet 50j that contacts magnet 200 is a south pole. In this configuration, magnetic flux flows from electromagnet 50j, through magnet 200, to electromagnet 50a.

As shown in FIG. 7, the magnetic flux generated from coil 52j passes through magnetic body 51j and is directed toward the side surfaces 230, 240 of magnet 200 in the circumferential direction of rotor 20. Similarly, the magnetic flux generated from coil 62j passes through magnetic body 61j and is directed toward the side surfaces 230, 240 of magnet 200 in the circumferential direction of rotor 20, and the magnetic flux generated from outer coil 72i passes through outer magnetic body 71i and is directed toward the side surfaces 230, 240 of magnet 200 in the circumferential direction of rotor 20.

As shown in FIG. 8, electromagnet 50j is located on the side surface 240 side of magnet 20a, and electromagnet 50a is located on the side surface 230 side of magnet 20a. In this configuration, magnet 20a is located between two

adjacent electromagnets

50j and 50a among the multiple electromagnets 500 in the circumferential direction.

In the magnetization process, magnetic flux directed in the direction of the rotation axis of the rotor 20 and magnetic flux directed in the circumferential direction toward the side surfaces 230, 240 of the magnet 200 pass through the side surfaces 230, 240 of the radially inner portion 212 of the magnet 200. For example, as shown in FIG. 8, part of the magnetic flux directed in the direction of the rotation axis passes from the

magnetic bodies

51j and 61j through the yoke 4a1 toward the side surface 240 of the magnet 20a. The magnetic flux then passes through the side surface 230 of the magnet 20a and the yoke 4a2 to flow to the

magnetic bodies

51a and 61a. In this case, one side surface 230 of the magnet 200 is magnetized to the north pole, and the other side surface 240 is magnetized to the south pole.

In this magnetization process, as shown in FIG. 6, the magnetic flux from the outer coil 72b of the outer electromagnet 700 toward the magnet 20b flows mostly to the radially outer portion 211 of the magnet 20b, but not so much to the radially inner portion 212 of the magnet 20b. As a result, the magnetic force of the radially inner portion 212 of the magnet 200 is smaller than the magnetic force of the radially outer portion 211 by the magnetization process using the outer electromagnet 700 alone.

On the other hand, as shown in FIG. 8, the magnetic flux from the

coils

52j and 62j of the

electromagnets

500 and 600 toward the magnet 20a flows more toward the radially inner portion 212 of the magnet 20a. This increases the magnetization rate of the radially inner portion 212 of the magnet 200.

In this embodiment, the portion of magnetic body 510 that contacts magnet 200 and the portion of magnetic body 610 that contacts magnet 200 have the same polarity. In this case, the magnetic flux that flows from magnetic body 510 in the direction of the rotation axis and the magnetic flux that flows from magnetic body 610 in the direction of the rotation axis repel each other. With this configuration, as shown in FIG. 4, a portion with a low magnetization rate is formed in first region 201 close to the position where the magnetic fluxes repel each other.

Even in this case, the magnetization rate of the second region 202 located near the magnetic body 510 and the third region 203 located near the magnetic body 610 in the radially inner portion 212 of the magnet 200 is approximately equal to the magnetization rate of the radially outer portion 211 of the magnet 200. As a result, the portion of the magnet 200 with low magnetic force can be made smaller compared to the case where the outer electromagnet 700 is used for magnetization.

Then, the yoke 400 is removed from the gap 330 after the magnetization process is completed. This causes the gap 330 to become a flux barrier in the rotor 20 in which the magnet 200 is magnetized.

In this embodiment, the coils 520 of two electromagnets 500 adjacent in the circumferential direction are formed in positions that do not interfere with each other. For example, as shown in FIG. 6, coil 52a is wound above magnetic body 51a in the axial direction, while

coils

52b and 52j, which are adjacent to coil 52a in the circumferential direction, are wound below

magnetic bodies

51b and 51j in the axial direction. The same is true for coil 620. In other words, coils 52b and 52j, which are adjacent to coil 52a in the circumferential direction, are in different positions in the axial direction.

As described above, the rotor magnetization device 10 in this embodiment magnetizes the rotor 20 having the rotor core 100 with the hole 310 and the magnet 200 housed in the hole 310 of the rotor core 100. The rotor magnetization device 10 includes a plurality of

electromagnets

500, 600 arranged in the circumferential direction. The

electromagnets

500, 600 include

magnetic bodies

510, 610 and coils 620, 620 wound around the

magnetic bodies

510, 610. The winding axis direction of the

coils

520, 620 is the axial direction of the rotor 20, and the magnetic flux generated from the

coils

520, 620 passes through the

magnetic bodies

510, 610 and is directed toward the side surfaces 230, 240 of the magnet 200 in the circumferential direction of the rotor 20. With this configuration, the magnetization rate can be improved even in the radially inner portion 212 of the magnet 200, and therefore the magnetization rate of the rotor 20 can be improved.

[Modification]
Although the configuration of the present embodiment has been described above, the embodiment is not limited thereto. For example, the magnetizing device 10 has been described as including both the

electromagnets

500 and 600 and the outer electromagnet 700, but may have a configuration including only one of them.

Although the configuration in which the yoke 400 is disposed in the gap 330 of the rotor core 100 and the

magnetic bodies

510 and 610 contact the yoke 400 has been described, the embodiment is not limited to this. For example, a configuration in which a portion of the magnetic body is inserted into the gap 330 of the rotor core 100 is also possible. In this case, the portion of the magnetic body inserted into the gap 330 contacts the

side surface

230 or 240 of the magnet 200. Note that since the upper magnetic body and the lower magnetic body repel each other, the upper magnetic body and the lower magnetic body do not need to contact each other.

The present invention has been described above based on the embodiment and various modifications, but it goes without saying that the present invention is not limited to the embodiment and various modifications, and various modifications are possible within the scope of the present invention without departing from the gist of the invention. Such modifications that do not depart from the gist of the invention are also included in the technical scope of the present invention, and this will be clear to those skilled in the art from the description of the claims.

1 motor, 10 magnetization device, 20 rotor, 70 housing, 80 shaft, 81 bearing, 90 stator, 91 stator core, 92 insulator, 93 coil, 100 rotor core, 110 magnetic pole portion, 112 extension portion, 120 annular portion, 130 connection portion, 200 magnet, 201 first region, 202 second region, 203 third region, 211 radial direction outer part, 212 radially inner part, 230, 240 side, 250, 260 side, 270 side, 310 hole, 320 gap, 330 gap, 400 yoke, 500, 600 electromagnet, 510 upper magnetic body, 520 upper coil, 610 lower magnetic body, 620 lower coil, 700 outer electromagnet, 710 outer magnetic body, 720 outer coil, 730 support

Claims

A magnetizing device that magnetizes a rotor having a rotor core with holes and magnets housed in the holes of the rotor core, the magnetizing device including a plurality of electromagnets arranged in a circumferential direction,
The electromagnet includes a magnetic body and a coil wound around the magnetic body,
a winding axis direction of the coil is the axial direction of the rotor,
The magnetic flux generated from the coil passes through the magnetic body and is directed toward a side surface of the magnet in the circumferential direction of the rotor.
Rotor magnetization device.
The electromagnet is
An upper coil is wound around an upper magnetic body, and a lower coil is wound around a lower magnetic body,
the upper magnetic body and the lower magnetic body face each other in the axial direction of the rotor,
a hole in the rotor core is located between the upper coil and the lower coil in the axial direction;
The rotor magnetizing device according to claim 1 .
The rotor magnetization device according to claim 1 or 2, wherein the magnet is positioned between two adjacent electromagnets of the plurality of electromagnets in the circumferential direction.
the plurality of electromagnets includes an outer electromagnet radially adjacent to the electromagnet;
The electromagnet is disposed inside the outer electromagnet in the radial direction,
The outer electromagnet faces the rotor core in a radial direction.
4. The rotor magnetizing device according to claim 1, wherein the magnetizing device is a magnetizing member.
A rotor core and a magnet are provided.
In a radial direction, the rotor core includes an annular portion located on an inner side, a magnetic pole portion located on an outer side of the annular portion, and a connection portion connecting the annular portion and the magnetic pole portion,
There is a gap between the magnetic pole portion and the connection portion in the circumferential direction,
a radially inner portion of the magnet protruding toward the annular portion includes a first region having a low magnetic force, and second and third regions having a high magnetic force;
In the axial direction, the first region is between the second region and the third region.
Rotor.
The rotor of claim 5, wherein the magnetic force in the first region is smaller than the magnetic force in the radially outer portion of the magnet.
The rotor of claim 5, wherein the magnetization rate in the first region is smaller than the magnetization rate in the radially outer portion of the magnet.
The magnetic pole portion includes a portion extending radially toward the annular portion,
A portion extending toward the annular portion in the circumferential direction is in contact with a side surface of a radially outer portion of the magnet,
A side surface of the magnet at a radially inner portion is exposed to a portion extending toward the annular portion.
A rotor as claimed in claim 5.
A rotor according to any one of claims 5 to 8;
A shaft,
A stator;
Equipped with
The magnetic pole portion faces the stator in a radial direction.
motor.
A manufacturing method of a rotor having a rotor core with a hole and a magnet housed in the hole of the rotor core, comprising the steps of:
a magnetizing step of magnetizing a side surface of a magnet housed in a hole of the rotor core in a circumferential direction of the rotor;
A method for manufacturing a rotor.
the magnet includes a radially outer portion in contact with an inner surface of the hole, and a radially inner portion protruding radially inward from the inner surface of the hole,
The magnetizing step includes a step of magnetizing a side surface of an inner portion of the magnet in the radial direction in a circumferential direction.
A method for manufacturing a rotor according to claim 10.
The method for manufacturing a rotor according to claim 10, wherein in the magnetization process, the magnetic flux directed in the direction of the rotor's rotation axis and the magnetic flux directed in the circumferential direction to the side of the magnet pass through the side of the inner portion of the magnet in the radial direction.
In the circumferential direction of the rotor, there is a gap between the magnet housed in the hole and the rotor core,
In the magnetization step,
The method includes the step of disposing an electromagnet in the gap.
A method for manufacturing a rotor according to any one of claims 10 to 12.
The electromagnet includes a coil and a magnetic body around which the coil is wound,
The magnetizing step includes a step of contacting the magnetic body with a side surface of the magnet.
A method for manufacturing a rotor according to claim 13.