JP2016208615A - Rotor for dynamo-electric machine and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnet-embedded rotor for dynamo-electric machine capable of outputting a high torque while reducing the cost of the permanent magnets formed in the rotor core by compression molding, and to provide a manufacturing method therefor.SOLUTION: In a state where the axial direction of the insertion hole 6 of a rotor core 2 is the vertical direction, a magnet fitting hole 4 has a taper inner surface 13 formed so that the hole dimension decreases from the upper end toward the lower end, and is fitted with a permanent magnet 3. The rotor core 2 is casted using cast iron (spherical graphite cast iron), and a plurality (10) of magnet fitting holes 4 are formed simultaneously by a casting mold. At this time, the taper inner surface 13 is formed by the draft slope of casting. The permanent magnet 3 is compression molded by a press device consisting of a dice 7 and a punch 9, by using a magnetic powder material (samarium iron nitrogen) 11 having a large coercive force. The spherical graphite cast iron has a strength of several times that of ordinary cast iron, and is used in a rotor core 2 requiring high strength, because it is excellent in toughness.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a rotor for a rotating electrical machine used as an electric motor and a generator and a method for manufacturing the same.

  Conventionally, some rotary electric machines have a so-called embedded magnet type rotor in which a permanent magnet is embedded and fixed in a rotor core. This rotor for a rotating electrical machine is orthogonal to the radial direction by inserting or forming a permanent magnet into a single or U-shaped magnet mounting hole (slot) extending in the axial direction formed in a rotor core in which electromagnetic steel plates are laminated, for example. What is arranged in such a way is known. In a rotating electrical machine (IPM motor) equipped with such an embedded magnet type rotor, not only magnet torque by a permanent magnet but also reluctance torque is generated. Therefore, a so-called surface magnet type rotor in which a permanent magnet is fixed to the surface of a rotor core. Compared to a rotating electrical machine (SPM motor) equipped with

  And as a permanent magnet used for the rotor of an IPM motor, a bond magnet may be used from the viewpoints of freedom of shape and ease of processing. In this bonded magnet, a magnet mounting hole of a rotor core formed by laminating electromagnetic steel sheets is filled with, for example, a rare earth-based magnetic powder material, and compression molding is performed with a die and a punch of a press device, thereby forming a permanent magnet. A manufacturing method has been proposed (see, for example, Patent Document 1).

JP 2009-44795 A

  However, in the method using compression molding as described above, since the magnetic powder material is repeatedly compression molded by directly punching the plurality of magnet mounting holes formed in the rotor core, the gap between the side surfaces of the punch and the magnet mounting holes The magnetic powder material may leak out. As a result, biting and insufficient compression may occur. For this reason, in order to arrange a permanent magnet on the rotor core by compression molding, it is necessary to ensure high dimensional accuracy of the magnet mounting hole, and if the magnet mounting hole is processed accurately, the processing cost increases.

  When a rotor core is formed by laminating electromagnetic steel plates, for example, if a U-shaped permanent magnet is disposed, the magnetic steel sheet has a low saturation magnetic flux density, and the magnetic flux density is saturated near the outer periphery of the rotor core. Since it cannot be made sufficiently high, the effective magnetic flux number of the permanent magnet is reduced and the magnetic properties of the rotor are deteriorated. As a result, it is difficult to manufacture a rotor core and a rotor that can output high torque, and to obtain an IPM motor.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to reduce the cost of a permanent magnet formed on a rotor core by compression molding and to rotate a magnet embedded type capable of outputting high torque. An object of the present invention is to provide an electric rotor and a method for manufacturing the same.

  In order to solve the above-mentioned problems, the invention described in claim 1 is a rotor for a rotating electrical machine, wherein the rotor is integrally fixed to a rotating shaft, and a plurality of magnet mounting holes extend in the axial direction at intervals in the circumferential direction. And a permanent magnet embedded and fixed in each magnet mounting hole, and the permanent magnet compression-molds the magnetic powder material filled in the magnet mounting hole. The gist is that it was formed.

  According to the said structure, a permanent magnet is formed by compression-molding magnetic powder material in the several magnet attachment hole formed in the rotor core shape | molded with cast iron. For this reason, a rotor core having a high saturation magnetic flux density can be formed, and a rotor for a rotating electrical machine in which a permanent magnet that can be easily formed by compression is embedded can be formed. As a result, a magnet-embedded rotor and rotating electrical machine capable of outputting high torque can be realized.

  According to a second aspect of the present invention, there is provided a rotor core made of cast iron which is fixed to a rotating shaft so as to be integrally rotatable, and has a plurality of magnet mounting holes extending in the axial direction at intervals in the circumferential direction. In a method for manufacturing a rotor for a rotating electrical machine comprising a permanent magnet embedded and fixed in a hole, a rotor core forming step of forming the rotor core provided with the magnet mounting hole with the cast iron, A filling step of filling each magnet mounting hole with a magnetic powder material, a die disposed in close contact with one end of the rotor core, and a hole facing the magnet mounting hole; and a hole in the die And a compression molding step of compressing and molding the magnetic powder material filled in the magnet mounting holes using a punch to be driven.

  According to the said structure, the rotor core in which the magnet attachment hole was formed is shape | molded with cast iron (rotor core shaping | molding process), and the magnetic powder material is filled in the magnet attachment hole formed in the rotor core (filling process). Thereafter, a punch is driven into a die hole arranged in close contact with one end of the rotor core in the axial direction, and the magnetic powder material is compressed (compression molding process) to form a permanent magnet. As a result, the magnetic powder material is not pressed by the die and the punch and leaks from the magnet mounting hole. For this reason, the rotor core which has a high saturation magnetic flux density and does not require the dimensional accuracy of the magnet mounting hole can be formed. Thereby, the processing cost for forming a permanent magnet can be reduced, and the rotor which can output a high torque can be manufactured.

  According to a third aspect of the present invention, in the method for manufacturing a rotor for a rotating electrical machine according to the second aspect, in the rotor core forming step, the hole size is shortened from one end portion in the axial direction to the other end portion of the rotor core. The magnet mounting hole having a tapered inner surface is formed of a mold, and the compression molding step is such that one side of the magnet mounting hole in a state having the tapered inner surface and the hole of the die face each other in the axial direction. The gist is that the punch is driven in the axial direction into the hole of the die.

  According to the said structure, a compression molding is shape | molded by compression by arrange | positioning a die | dye to the one side of the axial direction of a magnet attachment hole, and driving a punch into the axial direction of a die | dye. Thereby, even if the taper inner surface of the magnet mounting hole is still formed, compression molding can be performed, so that it is not necessary to perform additional machining of the magnet mounting hole with high accuracy. As a result, a cost reduction effect can be expected.

  ADVANTAGE OF THE INVENTION According to this invention, the rotor for permanent magnets which can reduce the cost of the permanent magnet formed in a rotor core by compression molding, and can output a high torque, and its manufacturing method can be provided.

Sectional drawing of the rotor for rotary electric machines which concerns on one Embodiment of this invention. The longitudinal cross-sectional view of the permanent magnet part of the rotor core seen from the XX direction in FIG. The figure which shows the manufacturing process of the rotor for rotary electric machines. (A)-(c) is the schematic explaining each process of forming a permanent magnet by compression molding. (A) is the arrangement | positioning process of the rotor core before forming a permanent magnet, (b) is a filling process of a magnetic powder material, (c) is a figure which shows a compression molding process. Sectional drawing of the rotor for rotary electric machines which concerns on other embodiment of this invention.

  Below, the rotor 1 for rotary electric machines used for the rotary electric machine of embodiment of this invention is demonstrated based on the figure of the rotor of an IPM motor. In the following description, the radial direction and the axial direction refer to the radial direction and the axial direction of the rotor 1 (rotor core 2) for a rotating electrical machine.

FIG. 1 is a cross-sectional view of a rotating electrical machine rotor (hereinafter referred to as a rotor) 1 according to an embodiment of the present invention.
The rotating electrical machine is mounted on a vehicle, for example, and is used as an electric motor (for example, a three-phase brushless motor) for a drive source of an electric power steering device that assists steering operation or an electric oil pump device that generates hydraulic pressure.

  As shown in FIG. 1, the rotor 1 is composed of a columnar rotor core 2 and a permanent magnet 3 that are fixed so as to be integrally rotatable with a rotating shaft 5 of a rotating electrical machine (in this embodiment, an IPM motor). A plurality (10 in this embodiment) of permanent magnets 3 are embedded in the rotor core 2 and fixed to the rotor core 2. That is, the rotor 1 of the present embodiment is configured as a so-called embedded magnet type rotor. The rotating electrical machine configured as described above has a magnetic attractive force and a repulsive force generated between a magnetic field formed by supplying driving power to each coil of a stator (not shown) and a magnetic flux of the permanent magnet 3. Thus, the rotor 1 is configured to rotate.

  The rotor core 2 is formed in a substantially cylindrical shape using iron or the like, and has an insertion hole 6 into which the rotating shaft 5 of the rotating electrical machine is inserted. The rotor core 2 is formed with a plurality (ten in this embodiment) of substantially U-shaped magnet mounting holes 4 in which the permanent magnets 3 are respectively disposed. In addition, the magnet attachment hole 4 of this embodiment is formed in the hole (cavity) shape which has substantially the same cross-sectional shape as the cross-sectional shape of the permanent magnet 3, respectively.

  Specifically, the rotor core 2 is formed by casting using cast iron (for example, spheroidal graphite cast iron or the like). Cast iron is a soft magnetic material containing carbon containing iron as a main component, and spheroidal graphite cast iron containing a large amount of carbon is effective in securing the strength of the rotor core 2. Each magnet mounting hole 4 is formed by a mold (for example, a sand mold) when the rotor core 2 is molded.

  Each permanent magnet 3 is accommodated in each of ten substantially U-shaped magnet mounting holes 4 penetratingly formed in the axial direction in the vicinity of the outer peripheral edge of the rotor core 2 and fixedly held on the rotor core 2. The magnet mounting holes 4 extend from both distal ends (U-shaped distal end portions) on the outer side in the radial direction so as to face each other in the circumferential direction and approach each other toward the inner side in the radial direction. The U-shaped bottom portion is formed in a substantially arc shape with a convex shape.

  In addition, the permanent magnet 3 of the present embodiment uses a rare earth-based magnet (for example, samarium iron nitrogen, etc.) obtained by molding and solidifying fine magnetic powder (magnetic powder material, which may include a part of the lubricant). Yes. Samarium iron nitrogen is a hard magnetic material that forms a magnet with high coercivity. After the magnetic powder material is compression molded into the magnet mounting hole 4 to form a magnetic powder compression molded body, it is magnetized (magnetized) to form the permanent magnet 3. Furthermore, the permanent magnet 3 is magnetized so that one polarity (for example, S pole) faces in the circumferential direction. And the other permanent magnet 3 and the other polarity (for example, N pole) oppose in the circumferential direction.

FIG. 2 is a longitudinal sectional view of the permanent magnet 3 portion of the rotor core 2 as viewed from the XX direction in FIG.
As shown in FIG. 2, in the state where the axial direction of the insertion hole 6 of the rotor core 2 is vertical, the magnet mounting hole 4 has a shorter hole dimension from the upper end (one end) to the lower end (the other end). A tapered inner surface 13 is formed, and a permanent magnet (magnetic powder compression molding) 3 is embedded.

  The rotor core 2 is cast using cast iron (in this embodiment, spheroidal graphite cast iron (FCD)), and a plurality (10 in this embodiment) of magnet mounting holes 4 are simultaneously formed by a mold. At this time, the taper inner surface 13 is formed by a draft of casting (for example, about 1 to 2 °).

  The permanent magnet 3 is formed by compression molding using a press machine composed of a die 7 and a punch 9 using a magnetic powder (magnetic powder material, in this embodiment, samarium iron nitrogen) 11 having a large coercive force. Spheroidal graphite cast iron has several times the strength of gray cast iron (ordinary cast iron) and is excellent in toughness (stickiness), and is therefore suitable for the rotor core 2 requiring high strength.

Next, a method for manufacturing the magnet-embedded rotor 1 will be described.
FIG. 3 is a diagram showing a manufacturing process of the rotor 1, FIGS. 4A to 4C are schematic diagrams for explaining each step of forming the permanent magnet 3 by compression molding, and FIG. 3A is a permanent magnet. 3 is a diagram illustrating an arrangement process of the rotor core 2 before forming 3, (b) a filling process of the magnetic powder material 11, and (c) a compression molding process.

  First, the rotor core 2 is formed by casting using cast iron (in this embodiment, spheroidal graphite cast iron) (step S301, rotor core forming step). At the same time, a plurality (ten in this embodiment) of magnet mounting holes 4 having a tapered inner surface 13 in the rotor core 2 are formed by a mold.

  Next, the rotor core 2 is arranged between the lower press table 10 and the upper die 7 with the punch 9 raised so that the axial direction of the rotor core 2 is vertical (step S302, arrangement step). ). The upper surface (one end portion) of the rotor core 2 and the lower surface of the die 7 are in close contact with each other, and the upper side (one side) of the magnet mounting hole 4 and the punch hole 8 provided in the die 7 communicate with each other.

  Subsequently, the magnetic powder material 11 is filled into the magnet mounting hole 4 and the punch hole 8 through the punch hole 8 provided in the die 7 (step S303, filling step). The amount (mass) of the magnetic powder material 11 filled in the punch hole 8 is determined by the compressibility.

  Then, the punch 9 is driven into the punch hole 8 of the die 7 (for example, the gap on the side surface with the punch 9 is formed below the magnetic powder diameter), and the magnetic powder material 11 is compression-molded (step S304, compression molding process). The compression molding is performed on the magnetic powder material 11 in all the magnet mounting holes 4 at one time.

  Thereafter, a magnetic field is applied to the magnetic powder compression molded body 12 molded and fixed in the magnet mounting hole 4 of the rotor core 2 to perform a magnetization (magnetization) process to form the permanent magnet 3. (Step S305, magnetization process).

  Specifically, as shown in FIG. 4A, the punch hole 8 of the die 7 and the magnet mounting hole 4 of the rotor core 2 are opposed to each other between the lower press table 10 and the upper die 7. The rotor core 2 is disposed on the surface (arrangement step). At this time, the punch 9 is in a raised state.

  Next, as shown in FIG. 4B, the magnetic powder material 11 is filled into the magnet mounting hole 4 in the vertical direction through the punch hole 8 provided in the die 7 (filling step). The height of the die 7 is set by a ratio between the apparent density of the magnetic powder material 11 and the density of the compressed magnetic powder compression molded body 12 in the magnet mounting hole 4 (compression rate as a measure of volume reduction). Depends on the magnetic powder material and the molding pressure. For example, when the compression ratio is three times, the magnetic powder compression molded body 12 after molding becomes 1/3 of the amount of the filled magnetic powder material 11).

  Then, as shown in FIG. 4 (c), a punch 9 is driven into the punch hole 8 of the die 7, and the magnetic powder material 11 filled in the punch hole 8 is compression molded at once toward the magnet mounting hole 4 side. (Compression molding process). The magnetic powder material 11 is compressed in the magnet mounting hole 4 to form a magnetic powder compression molded body 12. In addition, since the dimensional accuracy of the punch hole 8 and the punch 9 is high, the magnetic powder material 11 is compression-molded without entering the gap between the side surfaces of the punch hole 8 and the punch 9.

  As described above, even if the taper inner surface 13 is formed in the axial direction of the magnet mounting hole 4 of the rotor core 2, the magnetic powder material 11 can be compression-molded by using the die 7 and the punch 9 without additional processing. it can.

  Next, operations and effects of the rotor 1 according to the embodiment of the present invention configured as described above will be described.

  According to the above embodiment, the magnetic powder material (samarium iron nitrogen in this embodiment) is provided in the magnet mounting hole 4 formed in the rotor core 2 formed using cast iron (in this embodiment, spheroidal graphite cast iron). The permanent magnet 3 is formed by compression molding 11. For this reason, the rotor core 2 having a high saturation magnetic flux density can be formed, and the rotor 1 embedded with the permanent magnet 3 that can be easily formed by compression can be formed. Thereby, the rotor 1 which can output a high torque is realizable.

  Further, the rotor core 2 is molded from cast iron (rotor core molding process), and the magnetic powder material 11 is filled into the magnet mounting holes 4 formed in the rotor core 2 (filling process). Then, a punch 9 is driven into a punch hole 8 provided in a die 7 disposed in close contact with the upper end of the rotor core 2 in the axial direction, and the magnetic powder material 11 is compressed (compression molding process). 3 is formed. As a result, the magnetic powder material 11 is not pressed by the die 7 and the punch 9 and leaks from the magnet mounting hole 4. For this reason, the rotor core 2 which has a high saturation magnetic flux density and does not require the dimensional accuracy of the magnet mounting hole 4 can be formed. Thereby, the rotor 1 which can reduce processing cost and can output a high torque can be manufactured.

  Further, a die 7 is disposed at the upper end of the taper inner surface 13 in the axial direction of the magnet mounting hole 4, and the punch 9 is driven in the axial direction into the punch hole 8, thereby compressing the magnetic powder material 11 and forming the magnetic powder compression molded body 12. Mold. Thereby, even if the taper inner surface 13 is still formed in the magnet mounting hole 4, compression molding can be performed, so that it is not necessary to perform additional machining of the magnet mounting hole 4 with high accuracy. As a result, a cost reduction effect can be expected.

  As described above, according to the embodiment of the present invention, a permanent magnet rotor that can reduce the cost of a permanent magnet formed on a rotor core by compression molding and can output high torque, and a method for manufacturing the rotor Can be provided.

  As mentioned above, although embodiment which concerns on this invention was described, this invention can also be implemented with another form.

  In the above embodiment, the case where the rotor core 2 is formed by casting using cast iron has been described. However, the present invention is not limited to this, and the rotor core 2 is formed by other methods such as forging or stamping. It may be.

  In the above-described embodiment, the case where the magnetic powder material 11 filled in the magnet mounting hole 4 is compression-molded at a time by driving the punch 9 once is not limited to this. The driving may be divided into several times and compressed.

  In the above embodiment, an example is shown in which a magnetic field is applied after compression molding and the magnetization process is performed. However, the present invention is not limited to this, and compression molding may be performed while applying a magnetic field.

In the above embodiment, ten magnet mounting holes 4 are provided, and the permanent magnet 3 has one polarity facing in the circumferential direction, and the other permanent magnet 3 is facing the other polarity in the circumferential direction. However, the present invention is not limited to this.
FIG. 5 is a cross-sectional view of a rotor 1 according to another embodiment of the present invention. As shown in FIG. 5, one polarity (N pole in this embodiment) is magnetized so as to oppose in the circumferential direction, and the other permanent magnet 3 and the other polarity (S in this embodiment) are arranged in the circumferential direction. The poles may be arranged so as to face each other.

  In the above-described embodiment, the filling is performed by another method, for example, by using an aeration method in which compressed air is injected from the side wall and the low-density magnetic powder material 11 is slowly put in, instead of filling by the vertical blow method. You may do it. Also, the compression method may use a punch that is pressed both up and down (for example, withdrawal method), or may be compressed while applying vibration.

  In the above embodiment, the present invention is embodied in an electric motor (IPM motor) used as a drive source such as an electric power steering device or an electric oil pump device. However, the present invention is not limited to this, and driving of other devices is possible. It may be used as a source motor. Moreover, you may use as a generator.

1: rotor for rotating electrical machine, 2: rotor core, 3: permanent magnet, 4: magnet mounting hole, 5: rotating shaft, 6: insertion hole, 7: die, 8: punch hole, 9: punch, 10: press stand,
11: Magnetic powder material, 12: Magnetic powder compression molding, 13: Tapered inner surface

Claims (3)

A rotor core made of cast iron which is fixed to the rotary shaft so as to be integrally rotatable, and has a plurality of magnet mounting holes extending in the axial direction at intervals in the circumferential direction;
A permanent magnet embedded and fixed in each magnet mounting hole,
The rotor for a rotating electrical machine, wherein the permanent magnet is formed by compression molding a magnetic powder material filled in the magnet mounting hole. A rotor core made of cast iron which is fixed to the rotary shaft so as to be integrally rotatable, and has a plurality of magnet mounting holes extending in the axial direction at intervals in the circumferential direction;
In a method for manufacturing a rotor for a rotating electrical machine, comprising a permanent magnet embedded and fixed in each magnet mounting hole,
A rotor core molding step of molding the rotor core provided with the magnet mounting holes with the cast iron;
A filling step of filling each magnet mounting hole of the rotor core with a magnetic powder material;
The magnet mounting holes are filled using a die that is arranged in close contact with one end of the rotor core and that has a hole facing the magnet mounting hole, and a punch that is driven into the hole of the die. And a compression molding step of compression molding the magnetic powder material. In the manufacturing method of the rotor for rotary electric machines according to claim 2,
In the rotor core molding step, the magnet mounting hole having a tapered inner surface whose hole size is shortened from one end of the rotor core in the axial direction toward the other end is formed by a mold,
In the compression molding step, one side of the magnet mounting hole having the tapered inner surface and the hole of the die are arranged so as to face each other in the axial direction, and the punch is placed in the hole of the die. A method for manufacturing a rotor for a rotating electrical machine, characterized by driving in an axial direction.

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