JP6744573B2 - Rotor unit and method for manufacturing rotor unit - Google Patents

Description

The present invention comprises a core in which thin plate-shaped members made of a magnetic material are laminated and a permanent magnet embedded in the core, and a plurality of cores are connected in the axial direction of the core to form a rotor, or One relates to a rotor unit that constitutes a rotor and a manufacturing method thereof.

For example, Patent Document 1 describes a rotor including a core in which a plurality of core members (thin plate-shaped members) formed by punching an electromagnetic steel plate are stacked so that the punching directions are aligned. The permanent magnet included in this rotor is formed by injection molding a magnet material into an insertion hole formed in the core. Here, the injection molding is performed by filling the magnetic material from the surface having a burr (burr surface) formed on each electromagnetic steel sheet by punching. It is described that this makes it possible to increase the permeance by the permanent magnet (paragraph "0046").

JP, 2016-123143, A

By the way, when the magnetic material is filled from the burr surface side as described above, the burr is deformed by the injection molding and this portion is separated from the core body, so that foreign matter may be generated in the injection molding process.

The present invention has been made in view of such circumstances, and an object thereof is to provide a rotor unit capable of suppressing the generation of foreign matter by filling an insertion hole formed in a core with a magnet material, and a manufacturing method thereof. To provide.

Hereinafter, the means for solving the above problems and the operation effects thereof will be described.
1. A rotor is provided, which comprises a core in which thin plate members made of a magnetic material are laminated and a permanent magnet embedded in the core, and a plurality of rotors are connected in the axial direction of the core, or a single rotor is used. In the constituting rotor unit, the core has an insertion hole penetrating the core in a direction intersecting a plane orthogonal to the axial direction and filled with the permanent magnet, and the permanent magnet is , A mixture of magnetic powder and resin is used as a magnetic material, and one of a pair of surfaces of the thin plate member orthogonal to the axial direction is a burr surface having a burr in a portion defining the insertion hole, and the other is the insertion. In each of the laminated thin plate-shaped members, the burr surface is located on one end surface (20b) side of the core in the axial direction. A gate mark is formed on the permanent magnet on the other end face side of the core in the axial direction.

In the above structure, the gate mark is formed on the permanent magnet on the other end side in the axial direction of the core. This means that the insertion hole was filled with the magnetic material from the other end side. That is, the magnetic material with which the insertion hole is filled means that the thin plate-shaped member is first filled with the sag surface side. As a result, it is possible to prevent the burr from being deformed when the magnet material is filled, and thus it is possible to suppress the generation of foreign matter as compared with the case where the burr surface is filled.

2. A rotor is provided, which comprises a core in which thin plate members made of a magnetic material are laminated and a permanent magnet embedded in the core, and a plurality of rotors are connected in the axial direction of the core, or a single rotor is used. In the method for manufacturing a rotor unit configured, an insertion hole penetrating the core in a direction intersecting a plane orthogonal to the axial direction is formed in the core, and the insertion hole is orthogonal to the axial direction of the thin plate member. The pair of surfaces, one of which is a burr surface having a burr in the portion defining the insertion hole, and the other is a sag surface having a sag in the portion defining the insertion hole, and one of the cores in the axial direction. A magnet, which is a mixture of magnetic powder and resin, in the insertion hole from the other end face side of the core in the axial direction with respect to the thin plate-shaped members laminated so that the burr face is located on the end face (20b) side of There is a filling step of filling the material.

According to the filling step, the magnetic material with which the insertion hole is filled is first filled with the thin plate member from the sag surface side. As a result, it is possible to prevent the burr from being deformed when the magnet material is filled, and thus it is possible to suppress the generation of foreign matter as compared with the case where the burr surface is filled.

3. In the method of manufacturing a rotor unit according to the above item 2, in the filling step, the magnet material is filled by injection molding.
4. In the method for manufacturing a rotor unit according to the above 3, there is a magnetizing step of applying a magnetic field to the magnet material filled in the insertion hole, and a period of the filling step and a period of the magnetizing step overlap. There is.

When the magnetic material is filled from the burr surface side in the filling step, the flow of the magnetic material tends to be disturbed. When the period of the filling step and the period of the magnetizing step are overlapped in the state where the flow of the magnetic material is disturbed, the magnetization rate of the permanent magnets generated through the magnetizing step and The orientation ratio is likely to decrease. In this respect, in the above method, since the magnet material is filled from the sagging surface side in the filling step, it is possible to suppress the decrease in the magnetization rate and the orientation rate.

The perspective view concerning one embodiment of a rotor unit. The top view of the thin plate-shaped member concerning the embodiment. 3-3 sectional drawing of FIG. Sectional drawing which shows the filling process concerning the embodiment. The partially expanded sectional view of the said filling process.

An embodiment of a rotor unit and a method of manufacturing the rotor unit will be described below with reference to the drawings.
The rotor unit 10 shown in FIG. 1 constitutes a rotor of an embedded magnet synchronous machine (IPMSM) alone. Specifically, in the rotor unit 10, the stators are arranged so as to face each other from the outside in the radial direction Dr, and thus the IPMSM is configured. This IPMSM is built in an electric power steering device (EPS). The rotor unit 10 has a cylindrical shape.

The rotor unit 10 includes a core 20 and a permanent magnet 40. The core 20 is formed by laminating a plurality of electromagnetic steel plates such as silicon steel plates. The core 20 is provided with 10 first insertion holes 22 and 10 second insertion holes 24 that penetrate in the axial direction Da. The first insertion hole 22 is filled with the first portion 42 of the permanent magnet 40, and the second insertion hole 24 is filled with the second portion 44 of the permanent magnet 40.

The first portion 42 and the second portion 44 extend in the radial direction Dr and are joined at the joint portion CON on the inner side in the radial direction Dr. The radial direction Dr is defined for each point on a plane including the cross section of the core 20 orthogonal to the axial direction Da, and from the point defining the radial direction Dr to the rotation center axis O of the rotor unit 10 shown in FIG. 1. It is the direction parallel to the downline. Therefore, the radial direction Dr changes depending on the points defining the radial direction Dr. In FIG. 1, however, the radial direction Dr at a point deviated to the left side in the drawing with respect to the rotation center axis O is particularly noticeable. Is illustrated.

The pair of the first portion 42 and the second portion 44, which are coupled to each other, have a substantially U-shaped cross section orthogonal to the axial direction Da. The pair of the first portion 42 and the second portion 44 coupled to each other is evenly arranged in the circumferential direction Dc of the core 20. The circumferential direction Dc of the core 20 is the tangential direction at a point defined above in a circle whose radius is the distance from the rotation center axis O to the point defining the circumferential direction Dc on a plane orthogonal to the axial direction Da. I will. Therefore, the circumferential direction Dc changes in accordance with the position defining the circumferential direction Dc, but in FIG. 1, the circumferential direction Dc at the lower position of the core 20 in the drawing is schematically illustrated. Is illustrated in. By the way, when the circumferential direction Dc and the radial direction Dr are defined at the same point, they are orthogonal to each other. Further, the axial direction Da is a direction parallel to the rotation center axis O.

FIG. 2 shows a planar configuration of the thin plate member 30 that constitutes the core 20. As shown in FIG. 2, the thin plate member 30 is formed with a first insertion hole 22 and a second insertion hole 24 in which the permanent magnet 40 shown in FIG. 1 is filled.

FIG. 3 shows a cross section taken along line 3-3 of FIG.
Since the first insertion hole 22 of the thin plate member 30 is formed by punching, the first insertion hole 22 of the thin plate member 30 protrudes toward the burr surface 32 side as shown in FIG. It has a burr 36 to do. Further, in the portion of the thin plate member 30 corresponding to the first insertion hole 22, there is a sag 38 in which the vicinity of the first insertion hole 22 is depressed on the sagging surface 34 side which is the back surface of the burr surface 32. This is formed by pressing a punch from the sagging surface 34 side of the thin plate member 30. Each thin plate member 30 has a burr 36 near the second insertion hole 24 on the burr surface 32 side, and has a sag 38 near the second insertion hole 24 on the sagging surface 34 side.

Here, the core 20 according to the present embodiment is laminated and formed such that one sag surface 34 and the other burr surface 32 of the pair of adjacent thin plate-shaped members 30 face each other. The rotor unit 10 is manufactured by filling the core 20 with the magnetic material that is the material of the permanent magnet 40.

FIG. 4 shows a filling process of the magnetic material according to this embodiment. The magnet material 40a shown in FIG. 4 is a material of the permanent magnet 40 and is a mixture of resin and magnetic powder.
As shown in FIG. 4, the core 20 is placed in the mold 60. Here, a magnetizing device 62 for applying a magnetic field to the magnet material 40 a in the core 20 is arranged outside the core 20 in the radial direction Dr. In the present embodiment, the magnetizing device 62 is assumed to have a permanent magnet. Further, a gate 64 for filling the first insertion hole 22 and the second insertion hole 24 with the magnetic material 40a is installed on the side of the first end surface 20a, which is one of the pair of end surfaces of the core 20 in the axial direction Da. Has been done. Here, in the present embodiment, the first end surface 20a is the sagging surface 34 of the thin plate member 30 that constitutes the first end surface 20a. As a result, in each of the thin plate-shaped members 30 forming the core 20, the sagging surface 34 is on the first end surface 20a side and the burr surface 32 is on the second end surface 20b side which is the back surface of the first end surface 20a.

Here, the operation of the present embodiment will be described.
When the core 20 is placed in the mold 60, the magnet material 40 a is filled in the first insertion hole 22 and the second insertion hole 24 by injection molding. Thereby, the magnetic material 40a is gradually filled from the first end surface 20a side of the core 20 to the second end surface 20b side which is the back surface of the first end surface 20a.

FIG. 5 shows an enlarged cross section near the first insertion hole 22 in the filling step.
As shown in FIG. 5, the magnet material 40 a filled in the first insertion holes 22 is filled in the first insertion holes 22 in each thin plate member 30 from the sagging surface 34 side.

When the magnet material 40a is filled up to the second end surface 20b side of the core 20, the filling process is completed. In the present embodiment, since the magnetic field is applied to the magnet material 40a in the filling step of the magnet material 40a, the magnetizing step of applying the magnetic field to the magnet material 40a overlaps with the filling step. After the filling step is completed, the core 20 is taken out of the mold 60, so that the magnetizing step is also completed.

When the core 20 is taken out from the mold 60 shown in FIG. 4, the magnet material 40a remaining in the gate 64 and the magnet material 40a filled in the first insertion hole 22 and the second insertion hole 24 are separated. To be done. Therefore, as shown in FIG. 1, on the first end surface 20a side of the core 20 of the rotor unit 10, the permanent magnet 40 has a gate trace 40b which is a trace of this division. In the present embodiment, in FIG. 1, one of the permanent magnets 40 forming the magnetic poles of the rotor unit 10 has a first portion 42 of the pair of adjacent permanent magnets 40 and a second portion 44 of the other permanent magnet 40. A gate mark 40b corresponding to the gate 64 is formed. This is a phenomenon that occurs because the common gate 64 is assigned to the one first portion 42 and the other second portion 44 of the adjacent permanent magnets 40.

As described above, in this embodiment, the burr 36 is deformed by the force applied to the burr 36 by the magnet material 40 a, as compared with the case where the magnet material 40 a is charged from the sag surface 34 side. It is suppressed, and by extension, the generation of foreign matter in the injection process is suppressed. Further, in the case of filling from the sag surface 34 side, as compared with the case of filling from the burr surface 32 side, the magnet material 40a is less likely to enter between the adjacent thin plate-shaped members 30, and the permanent magnet 40 in the rotor unit 10 is less likely to enter. Variation in quantity is suppressed. Therefore, according to the present embodiment, the torque constant of the motor in which the rotor unit 10 is mounted is less likely to vary.

According to this embodiment described above, the following effects can be further obtained.
(1) The period of the filling process and the period of the magnetizing process are overlapped. Here, when the magnet material 40a is filled from the burr surface 32 side in the filling step, the burr 36 is more likely to be deformed than when it is filled from the sag surface 34 side. The flow of the magnetic material 40a tends to be disturbed. When the period of the filling step and the period of the magnetizing step are overlapped in the state where the flow of the magnetic material 40a is disturbed, the permanent magnet 40 generated through the magnetizing step is magnetized as compared with the case where the flow is not disturbed. The magnetic susceptibility and orientation ratio tend to decrease. Therefore, in the present embodiment, the merit of filling the magnet material 40a from the sagging surface 34 side is particularly great.

Incidentally, the orientation ratio is the degree to which the easy magnetization direction is aligned in the direction parallel to the magnetic moment required for the permanent magnet 40. The magnetization rate is the degree to which the magnetic moments (magnetization directions) are aligned in one direction.

<Other embodiments>
Note that at least one of the items of the above-described embodiment may be changed as follows.
"About permanent magnets"
It is not essential that the cross-sectional shape orthogonal to the axial direction Da is U-shaped. For example, it may be V-shaped. In addition, for example, the first portion 42 and the second portion 44 may not be joined, and the cross-sectional shape orthogonal to the axial direction Da may be a U-shape that is divided into two at the joining portion CON shown in FIG. 1. Further, for example, the cross-sectional shape orthogonal to the axial direction Da may be a rectangular shape extending in the radial direction Dr.

"About insertion holes"
In the above embodiment, the first insertion hole 22 and the second insertion hole 24 are formed so as to extend in the axial direction Da, but the present invention is not limited to this. For example, the core 20 may be penetrated by extending in a direction intersecting both the plane orthogonal to the axial direction Da and the axial direction Da.

"About the magnetizing process"
In the above-described embodiment, the period of the filling step of filling the magnet material 40a in the first insertion hole 22 and the second insertion hole 24 and the period of the magnetizing step of magnetizing the magnet material 40a are overlapped. Not exclusively. For example, after the completion of the filling process, the magnetizing device 62 may be arranged to face the core 20 to start the magnetizing process. Alternatively, for example, the magnetizing device 62 may be configured to include an electromagnet, and after the filling step is completed, the electromagnet may be energized to enter the magnetizing step.

In the above embodiment, the magnetic field was applied in the radial direction of the core 20 in the magnetizing step, but the present invention is not limited to this. For example, as described in JP-A-2014-121116, the magnetic field may be applied not only in the radial direction of the rotor unit 10 but also in the axial direction. In this case, it is particularly effective to connect a plurality of rotor units 10 in the axial direction Da to form a rotor. Incidentally, when a plurality of rotor units 10 are connected in the axial direction Da to form a rotor, the gate mark 40b is not always formed on one end face side in the axial direction Da. That is, for example, when two rotor units 10 are connected in the axial direction Da to form a rotor, if the first end surfaces 20a shown in FIG. This means that the gate mark 40b is not formed in any of them. However, in this case, when the rotor is separated into the pair of rotor units 10, the gate marks 40b are formed on the first end face 20a side of each.

"About the gate mark 40b"
For example, the gate mark 40b generated when the rotor unit 10 is taken out from the mold 60 may be removed thereafter. In this case, the gate mark 40b does not remain on the rotor unit 10 mounted on the IPMSM.

"About the filling process"
It is not limited to injection molding. For example, compression molding may be used. This can be done, for example, as follows. That is, first, the molding guide in which the holes having the same shapes as the first insertion hole 22 and the second insertion hole 24 in FIG. 1 are formed is placed in contact with the first end surface 20a of the core 20. The first insertion hole 22 and the second insertion hole 24 are filled with a magnetic material. Next, pressure is applied so that the magnet material in the hole of the molding guide is filled in the first insertion hole 22 and the second insertion hole 24. Even when compression molding is performed in this manner, foreign matter may be generated due to a large force being applied to the burr 36, so it is effective to fill the magnet material from the sag 38 side.

In the above-described embodiment, the common gate 64 is allocated to the one first portion 42 and the other second portion 44 of the adjacent permanent magnets 40, but the present invention is not limited to this, and the first gate 42 of one of the adjacent permanent magnets 40 is not limited thereto. The magnet material 40a may be filled from each of the gates 64 in the portion 42 and the second portion 44 on the other side.

"others"
The thin plate member is not limited to an electromagnetic steel plate, and may be a plate-shaped magnetic body.
Further, the shape of the core is not limited to the cylindrical shape, and may be, for example, a shape in which the distance between the rotation center axis O and the outer circumference of the core is longer in the central portion of the magnetic pole than in the end portion of the magnetic pole.

The number of magnetic poles is not limited to that illustrated in the above embodiment.
The rotating electric machine is not limited to one in which the rotor and the stator face each other in the radial direction Dr, but may be an axial gap type rotating electric machine in which the rotor and the stator face each other in the axial direction Da.

The rotary electric machine with a built-in rotor unit is not limited to the one with built-in EPS. For example, it may be a variable gear ratio steering system built-in device, an electric pump system built-in device, or a device built in a device for switching between four-wheel drive and two-wheel drive in a vehicle.

DESCRIPTION OF SYMBOLS 10... Rotor unit, 20... Core, 20a... 1st end surface, 20b... 2nd end surface, 22... 1st insertion hole, 24... 2nd insertion hole, 30... Thin plate-shaped member, 32... Burr surface, 34... Drip surface , 36... Burr, 38... Drip, 40... Permanent magnet, 40a... Magnet material, 40b... Gate trace, 42... First part, 44... Second part, 60... Mold, 62... Magnetizing device, 64... Gate ..

Claims (4)

A rotor is provided, which comprises a core in which thin plate members made of a magnetic material are laminated and a permanent magnet embedded in the core, and a plurality of rotors are connected in the axial direction of the core, or a single rotor is used. In the constituent rotor unit,
The core has an insertion hole that penetrates the core in a direction intersecting a plane orthogonal to the axial direction and is filled with the permanent magnet.
The permanent magnet uses a mixture of magnetic powder and resin as a magnet material,
The pair of surfaces orthogonal to the axial direction of the thin plate-shaped member is a burr surface in which one has a burr in a portion defining the insertion hole, and the other is a sag surface having a sag in a portion defining the insertion hole. Yes,
In each of the laminated thin plate-shaped members, the burr surface is located on one end surface side of the core in the axial direction,
A rotor unit in which a gate mark is formed on the permanent magnet on the other end surface side of the core in the axial direction. A rotor is provided, which comprises a core in which thin plate members made of a magnetic material are laminated and a permanent magnet embedded in the core, and a plurality of rotors are connected in the axial direction of the core, or a single rotor is used. In the method of manufacturing the rotor unit to configure,
The core has an insertion hole penetrating the core in a direction intersecting a plane orthogonal to the axial direction,
The pair of surfaces orthogonal to the axial direction of the thin plate-shaped member is a burr surface in which one has a burr in a portion defining the insertion hole, and the other is a sag surface having a sag in a portion defining the insertion hole. Yes,
With respect to the thin plate-shaped members laminated so that the burr surface is located on one end surface side of the core in the axial direction, magnetic powder and resin are introduced into the insertion hole from the other end surface side of the core in the axial direction. A method of manufacturing a rotor unit having a filling step of filling a magnetic material which is a mixture of The method of manufacturing a rotor unit according to claim 2, wherein in the filling step, the magnet material is filled by injection molding. A magnetizing step of applying a magnetic field to the magnet material filled in the insertion hole,
The method for manufacturing a rotor unit according to claim 3, wherein the period of the filling step and the period of the magnetizing step overlap.

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