JP2003319584A - Buried magnet motor and method for assembling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a high torque by reducing the reluctance of the magnetic circuit by eliminating the air gap and to reduce a torque ripple to eliminate the unevenness in the air gaps of respective poles. <P>SOLUTION: In a buried magnet motor having a magnet 2 embedded in a rotor core 1, the core 1 is formed in a split structure of an inner rotor 11 and an outer rotor 12. V-shaped sandwiching parts 31, 32 for sandwiching the magnets are formed at the opposed parts of the rotor 11 and the rotor 12. The motor has the structure in which the magnets 2 are brought into close contact with the V-shaped sandwiching parts 31, 31 of the rotor 11 and the rotor 12 by the relative rotation of any one of the rotor 11 and the rotor 12. The method for assembling the same is provided. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an embedded magnet type motor in which a magnet is embedded in a rotor core.

[0002]

2. Description of the Related Art Motors having an embedded magnet type (IPM) structure have been known. In this structure, eddy current is unlikely to occur in the permanent magnet and the loss is small. Embedded magnet type (I
The PM) motor has a structure in which a magnet M is inserted and embedded in a rectangular space RS provided in the rotor R as shown in FIG.

[0003]

In the conventional IPM motor described above, the magnet M is inserted and embedded in the rectangular space RS provided in the rotor R. Therefore, the rectangular space RS of the rotor core is formed due to the machining tolerance of the product. Since a large gap, that is, an air gap, may occur between the magnet and the magnet M, the large air gap causes a large magnetic resistance of the magnetic circuit, a high torque cannot be obtained, and the air gap of each pole varies. There was a problem that the torque ripple increased.

That is, rare earth magnets are often used as the magnets used in the embedded magnet type (IPM) structure, and the magnets of several mm to
The processing accuracy of a magnet with a size of about 10 mm is about ± 0.05. In addition, a rotor in which silicon steel plates are laminated is often used as the rotor, and the tolerance of the pressed product is about ± 0.03. Therefore, the maximum air gap when assembling a magnet with a rectangular cross section into a rectangular space is 0.16 mm.

Further, in the conventional IPM motor, as shown in FIG. 7, the magnetic flux leaks and a magnetic flux loss occurs.
In FIG. 7, the smaller the size of the B part is, the larger the magnetic resistance is and the smaller the magnetic flux leakage is. However, in the press molding, the B part can be reduced only to about 0.3 mm.

Therefore, in the embedded magnet type motor in which a magnet is embedded in the rotor core, the present inventor has a rotor core having a two-divided structure of an inner rotor and an outer rotor, and the inner rotor and the outer rotor are arranged relative to each other. As a result of further research and development, focusing on the technical idea of the present invention that the magnet is brought into close contact with the sandwiching portion that sandwiches the magnet formed in the facing portion of the inner rotor and the outer rotor by the static rotation. , By eliminating the air gap in the part that becomes the magnetic path of the magnet embedding part, the magnetic resistance of the magnetic circuit is reduced and high torque can be obtained, and the torque ripple is eliminated in order to eliminate the variation in the air gap of each pole. The present invention has been achieved which achieves the object of reducing

[0007]

The embedded magnet type motor of the present invention (the first invention according to claim 1) is an embedded magnet type motor in which a magnet is embedded in a rotor core, wherein the rotor core is an inner rotor. A two-part structure with an outer rotor is formed, and a sandwiching part for sandwiching a magnet is formed in a facing part between the inner rotor and the outer rotor, and by relative rotation of either one of the inner rotor and the outer rotor,
A structure is provided in which the magnet is brought into close contact with the sandwiching portion of the inner rotor and the outer rotor.

The embedded magnet type motor of the present invention (the second invention according to claim 2) is the embedded magnet type motor according to the first invention, wherein the serrated uneven surface formed on the inner peripheral portion of the outer rotor and the inner rotor. The sandwiching portion for sandwiching the magnet is formed by the saw-toothed concavo-convex surface formed on the outer peripheral portion of.

In the embedded magnet type motor of the present invention (the third invention according to claim 3), in the second invention, the V-shaped concave portion of the saw-toothed concavo-convex surface of the outer rotor is formed. The size of the matching uneven surface is larger than the size of the adjacent uneven surface forming the V-shaped convex portion of the sawtooth shaped uneven surface formed on the outer peripheral portion of the inner rotor.

In the embedded magnet type motor of the present invention (the fourth invention according to claim 4), in the second invention, the magnet sandwiched by the sandwiching portions of the inner rotor and the outer rotor is a rotor core. It is arranged so as to be inclined with respect to the circumferential direction.

The embedded magnet type motor assembling method according to the present invention (the fifth aspect of the present invention) is such that a magnet is sandwiched between the outer rotor and the inner rotor where the rotor core is divided into two parts. A method of assembling an embedded magnet type motor, which comprises forming an attachment portion and arranging a magnet in the sandwiching portion,
Inside the outer rotor, the magnet is disposed in the sandwiching portion of either the outer rotor or the inner rotor, and the outer rotor and the inner rotor are rotated in a direction in which the distance between the facing portions becomes wider. The inner rotor is inserted into the inner rotor, and the outer rotor and the inner rotor are rotated in a direction in which the gap between the facing portions is narrowed, so that the magnet is brought into close contact with the sandwiching portion.

According to the embedded magnet type motor assembling method of the present invention (sixth aspect of the present invention), an inner rotor is inserted into an outer rotor having a rotor core having a two-part structure, and the outer rotor and the inner rotor are inserted. One of the magnets is rotated in a direction in which the opposing distance between the two becomes wider, and the magnet is inserted into a sandwiching portion that sandwiches the magnet formed in the opposing portion of the outer rotor and the inner rotor, and the magnet is inserted into the sandwiching portion. After the magnet is inserted, one of the outer rotor and the inner rotor is rotated in the direction in which the facing interval between the outer rotor and the inner rotor is narrowed, so that the magnet is brought into close contact with the sandwiched portion of the inner rotor and the outer rotor. It is the one.

[0013]

According to the embedded magnet type motor of the first aspect of the present invention having the above structure, in the embedded magnet type motor in which magnets are embedded in the rotor core, the rotor core has a two-part structure of an inner rotor and an outer rotor. The relative rotation of either the inner rotor or the outer rotor causes the magnets to be in close contact with the sandwiching portion that sandwiches the magnets formed at the facing portions of the inner rotor and the outer rotor, so that the air gap is reduced. By eliminating them, the magnetic resistance of the magnetic circuit is reduced, high torque can be obtained, and the torque ripple is reduced in order to eliminate the variation in the air gap of each pole.

In the embedded magnet type motor of the second invention having the above-mentioned structure, in the first invention, the sawtooth shape formed on the inner peripheral portion of the outer rotor constituting the sandwiching portion for sandwiching the magnet is provided. Since the magnet is brought into close contact with and sandwiched by the uneven surface and the sawtooth-shaped uneven surface formed on the outer peripheral portion of the inner rotor, it is possible to effectively eliminate the air gap.

In the embedded magnet type motor of the third invention having the above structure, in the second invention, the dimension of adjacent concave and convex surfaces forming the V-shaped concave portion of the sawtooth concave and convex surface of the outer rotor is the same. Since the size is larger than the size of the adjacent uneven surface forming the V-shaped convex portion of the sawtooth-shaped uneven surface formed on the outer peripheral portion of the inner rotor, the facing distance between the inner rotor and the outer rotor is widened, or This has the effect of enabling relative rotation for narrowing.

In the embedded magnet type motor of the fourth invention having the above structure, in the second invention, the magnet sandwiched by the sandwiching portions of the inner rotor and the outer rotor is arranged in the circumferential direction of the rotor core. Since the magnets are arranged so as to be inclined, it is possible to employ a magnet having a large area of a magnetic flux generating portion, and it is possible to obtain a high torque.

According to the method of assembling the embedded magnet type motor of the fifth aspect of the present invention having the above-mentioned structure, a sandwiching portion for sandwiching a magnet is formed at an opposing portion of an outer rotor and an inner rotor, each of which has a rotor core divided into two parts. A method for assembling an embedded magnet type motor in which a magnet is disposed in the sandwiching portion, wherein the magnet is disposed in the sandwiching portion of either the outer rotor or the inner rotor, The inner rotor is inserted into the outer rotor in a state in which the inner rotor and the inner rotor are rotated in a direction in which the gap between the facing portions is widened, and the outer rotor and the inner rotor are placed in a direction in which the gap between the facing portions is narrowed. Since the magnet is brought into close contact with the sandwiched portion by rotating, the magnetic resistance of the magnetic circuit is eliminated by eliminating the air gap by a simple rotating operation. Reduced, as well as to obtain a high torque, an effect of allowing the assembly of interior permanent magnet motor to reduce the torque ripple in order to eliminate variations in the air gap of each pole.

In the method of assembling the embedded magnet type motor according to the sixth aspect of the present invention having the above structure, the inner rotor is inserted into the outer rotor having the rotor core of a two-divided structure, and either one of the outer rotor and the inner rotor is inserted into the outer rotor. After the magnet is inserted into the sandwiching part that rotates in the direction in which the facing interval of the magnet becomes wider and sandwiches the magnet formed in the facing part of the outer rotor and the inner rotor, and the magnet is inserted into the sandwiching part. By rotating either one of the outer rotor and the inner rotor in a direction in which the facing interval between the two becomes narrower, the magnet is brought into close contact with the sandwiching portion of the inner rotor and the outer rotor, By eliminating the air gap by rotating operation, the magnetic resistance of the magnetic circuit is reduced and high torque can be obtained. An effect of allowing the assembly of interior permanent magnet motor to reduce the torque ripple in order to eliminate variations in the poles of the air gap.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The embodiments of the present invention will be described below.
This will be described with reference to the drawings.

(Embodiment) The embedded magnet type motor of the present embodiment is an embedded magnet type motor in which a magnet 2 is embedded in a rotor core 1 as shown in FIG. 1 to FIG. 11 and outer rotor 1
2 is divided into two parts, and V-shaped sandwiching portions 31 and 32 for sandwiching a magnet are formed in the facing portion between the inner rotor 11 and the outer rotor 12, and either of the inner rotor 11 and the outer rotor 12 is formed. By relative rotation of one side,
A structure is provided in which the magnet 2 is closely attached to the V-shaped sandwiching portions 31 and 32 of the inner rotor 11 and the outer rotor 12.

The embedded magnet type motor of this embodiment is applied to an electric power steering apparatus. The electric power steering apparatus 40 includes a rack housing 51 as shown in FIG.
1, a tube yoke housing 513 coaxially attached to the end of the rack housing 511, and an end housing 514 coaxially attached to the end of the tube yoke housing 513.

Each of these three housings is hollow and formed in a substantially cylindrical shape, and the rack shaft 512 is inserted into the inside thereof. A hollow iron motor shaft 1 is rotatably inserted in the tube yoke housing 513 via bearings 517 and 530.

A ball screw nut 516 is fixed to the motor shaft 1, and a rack shaft 512 is axially movably coupled to the motor shaft 1 via the ball screw nut 516. At both ends of the rack shaft 512, the ball joints 5
Tie rods 519 connected to the steered wheels via 18 are connected to each other.

The tube yoke housing 513 is
As shown in FIG. 5, a brushless DC motor 20 is mounted inside the brushless DC motor 20.
The motor shaft 1, which is the rotation shaft, is inserted through 0.

The brushless DC motor 20 includes an armature core 521 fixed to the inner peripheral surface of the tube yoke housing 513 and a magnet 2 embedded in the motor shaft 1. That is, the motor shaft 1 forms a magnetic path. Although not entirely shown, the armature core 52
1 has a plurality of teeth in the circumferential direction, and an armature winding is wound around each of the teeth.

The rotor core 1 has a two-part structure of an inner rotor 11 and an outer rotor 12 made of laminated steel plates as shown in FIGS.
The sandwiching portion for sandwiching the magnet 2 by the sawtooth-shaped uneven surface 121 formed on the inner peripheral portion of the outer rotor 12 and the sawtooth-shaped uneven surface 111 formed on the outer peripheral portion of the inner rotor 11. 32 and 31 are configured.

As shown in FIGS. 1 and 2, the dimensions of the adjacent concave and convex surfaces forming the V-shaped concave portion 12C of the saw-tooth concave and convex surface 121 of the outer rotor 12 are the outer peripheral portion of the inner rotor 11. Sawtooth-shaped uneven surface 1 formed on
It is set to be larger than the dimension of the adjacent uneven surface forming the V-shaped convex portion 11P of 11.

The magnet 2 sandwiched by the sandwiching portions 31, 32 of the inner rotor 11 and the outer rotor 12 is
It is arranged so as to be inclined with respect to the circumferential direction of the rotor core 1.

The method of assembling the embedded magnet type motor constituting the brushless DC motor 20 is as follows.
The magnet 2 is embedded in the rotor, which will be described in detail below.

The inner rotor 11 is inserted into the outer rotor 12 in which the rotor core 1 is divided into two parts.
As shown in FIG. 5, either one of the outer rotor 12 and the inner rotor 11 is rotated in a direction in which the facing distance between the outer rotor 12 and the inner rotor 11 is widened, and the magnet formed in the facing portion between the outer rotor 12 and the inner rotor 11 is sandwiched. The magnet 2 having a rectangular cross section is inserted into the substantially rectangular sandwiching portion 1S.

After the magnet 2 is inserted into the sandwiched portion 1S, as shown in FIG. 1, one of the outer rotor 12 and the inner rotor 11 is arranged in a direction in which the facing interval between them becomes narrow (for example, a watch). Direction), the magnet 2 is brought into close contact with the sandwiching portion 1S of the inner rotor 11 and the outer rotor 12.

In the embedded magnet type motor of this embodiment, in the embedded magnet type motor in which the magnet 2 is embedded in the rotor core 1, the rotor core 1 has a two-part structure of an inner rotor 11 and an outer rotor 12, Rotor 1
1 and the outer rotor 12 rotate relative to each other, the sandwiching portions 31, 3 sandwiching the magnet 2 formed at the portion where the inner rotor 11 and the outer rotor 12 face each other.
Since the magnet 2 is closely attached to the magnet 2, the magnetic resistance of the magnetic circuit is reduced by eliminating the air gap, and a high torque can be obtained, and a torque ripple is generated in order to eliminate the variation in the air gap of each pole. It has the effect of making it smaller.

Further, in the embedded magnet type motor of this embodiment, the saw-toothed concavo-convex surface 121 formed on the inner peripheral portion of the outer rotor 12 constituting the sandwiching portions 31, 32 for sandwiching the magnet 2 is provided. Since the magnet 2 is closely contacted and sandwiched by the saw-toothed concavo-convex surface 111 formed on the outer peripheral portion of the inner rotor 11, the air gap can be effectively eliminated. With this configuration, the distance between the magnet 2 and the stator becomes longer, but since the rotor core 1 is made of a material having a high magnetic permeability (for example, a silicon steel plate), there is no problem such as a weak torque. Absent.

That is, in this embodiment, since the air gap is effectively eliminated, the magnetic flux can be effectively utilized, the magnetic flux leakage can be reduced, the magnetic flux loss can be suppressed, and a large torque can be obtained. When the torque is constant, the motor can be downsized.

Further, the embedded magnet type motor of this embodiment is
The dimension of the adjacent uneven surface forming the V-shaped concave portion 12C of the sawtooth-shaped uneven surface 121 of the outer rotor 12 is
Since the size of the adjacent uneven surface forming the V-shaped convex portion 11P of the sawtooth-shaped uneven surface 111 formed on the outer peripheral portion of the inner rotor 11 is larger than the distance between the inner rotor 11 and the outer rotor 12 facing each other. The effect of enabling relative rotation for widening or narrowing is achieved.

In the embedded magnet type motor of this embodiment, the inner rotor 11 and the outer rotor 12 are sandwiched by the sandwiching portions 3 therebetween.
Since the magnets 2 sandwiched by 1 and 32 are arranged so as to be inclined with respect to the circumferential direction of the rotor core 1, it is possible to adopt a magnet having a large area of a magnetic flux generating portion, and high torque The effect of being obtained is produced. That is, in the conventional embedded magnet type motor, the magnets are arranged in the circumferential direction as shown by the broken line in FIG. 8, whereas in the present embodiment, as shown by the solid line in FIG. Since the magnets 2 are arranged so as to be inclined, the width of the magnets is increased by 10% as compared with the conventional one, so that the magnetic flux that can be supplied by the magnets is increased by 10%.

Furthermore, in the method of assembling the embedded magnet type motor according to the present embodiment, the magnet is attached to the sandwiching portion of either the outer rotor or the inner rotor, and the outer rotor and the inner rotor are attached to the facing portion. The inner rotor is inserted into the outer rotor in a state of being urged to widen the gap, and the outer rotor and the inner rotor are rotated in a direction in which the gap between the facing portions becomes narrower, thereby sandwiching Since the magnet is brought into close contact with the part, the air gap can be eliminated by a simple rotation operation to reduce the magnetic resistance of the magnetic circuit and obtain a high torque, and also to improve the air gap of each pole. In order to eliminate it, it is possible to assemble an embedded magnet type motor that reduces torque ripple.

That is, in this embodiment, the IPM motor is constructed by dividing the rotor core 1 into two parts, and both the inner rotor 11 and the outer rotor 12 are made of laminated steel plates. The magnet 2 is arranged on the surface of the inner rotor 11, and the outer rotor 12 is covered with being rotated in the counterclockwise direction (CCW direction). Next, by rotating the outer rotor 12 clockwise (CW direction), the outer rotor 12 is rotated.
It is possible to close the gap between the magnet and the magnet 2. Therefore, by categorizing the dimensions of the magnet 2 into ranks, the air gap does not vary and can be almost zero. That is, since the magnetic resistance can be reduced, the magnetic flux can be effectively used by adopting the structure in which the air gap is not generated. In addition,
When assembling, the magnet 2 may be arranged on the outer rotor 12 and the inner rotor 11 may be inserted.

Further, there is an advantage that the torque ripple is less likely to occur because the variation of the air gap of each pole becomes small.
Further, in this structure, since the magnetic resistance of the short-circuit magnetic path connecting the NS poles of the magnet itself can be made large, magnetic flux leakage can be made small and magnetic flux loss can be suppressed.

The embodiments described above are merely examples for the purpose of explanation, and the present invention is not limited to them. Those skilled in the art will recognize from the claims, the detailed description of the invention and the description of the drawings. Modifications and additions can be made without departing from the technical idea of the present invention.

In the above-described embodiment, as an example, the magnet 2 is arranged on the surface of the inner rotor 11, the outer rotor 12 is covered in a state of being rotated counterclockwise (CCW direction), and then the outer rotor 12 is clockwise. (CW direction)
Although the example of the method of assembling the embedded magnet type motor in which the gap between the outer rotor 12 and the magnet 2 is closed and brought into close contact with each other by rotating the outer rotor 12 has been described, the present invention is not limited thereto and, for example, the outer rotor 12 A magnet may be arranged on the surface of the inner rotor and the inner rotor is inserted into the outer rotor of the rotor core having a two-part structure.
One of the outer rotor and the inner rotor is rotated in a direction in which the facing distance between the outer rotor and the inner rotor is widened, and a magnet is inserted into a sandwiching portion that sandwiches the magnet formed in the facing portion between the outer rotor and the inner rotor. After the magnet is inserted into the sandwiching portion, by rotating one of the outer rotor and the inner rotor in a direction in which the facing gap between the outer rotor and the inner rotor becomes narrower, the sandwiching portion between the inner rotor and the outer rotor is The embodiment of the method of assembling the embedded magnet type motor in which the magnets are closely contacted can be adopted.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a main part of an embedded magnet type motor according to an embodiment of the present invention in a state where a gap is zero.

FIG. 2 is a cross-sectional view showing a main part of the embedded magnet type motor according to the present embodiment with a gap formed.

FIG. 3 is a plan view showing an inner rotor and an outer rotor in the embedded magnet type motor of the present embodiment.

FIG. 4 is a partially cutaway sectional view showing an electric power steering apparatus to which the motor according to the present embodiment is applied.

FIG. 5 is a partially enlarged cross-sectional view showing a motor section of the electric power steering apparatus to which the present embodiment is applied.

FIG. 6 is a partial cross-sectional view showing a conventional IPM motor.

FIG. 7 is a partial cross-sectional view for explaining leakage of magnetic flux in a conventional IPM motor.

FIG. 8 is a comparison diagram for comparing the positional relationship between magnets embedded in the rotor of the conventional IPM motor and the motor of the present embodiment.

[Explanation of symbols]

1 rotor core 2 magnets 11 Inner rotor 12 Outer rotor 31, 32 sandwiching part

Claims (6)

[Claims] 1. An embedded magnet type motor in which a magnet is embedded in a rotor core, wherein the rotor core is composed of an inner rotor and an outer rotor.
With a split structure, a sandwiching portion that sandwiches a magnet is formed at a portion where the inner rotor and the outer rotor face each other, and relative rotation of either the inner rotor or the outer rotor causes the inner rotor and the outer rotor to rotate. An embedded magnet type motor comprising a structure for closely contacting the magnet with the sandwiching portion. 2. The magnet according to claim 1, wherein the magnet is sandwiched by a sawtooth-shaped uneven surface formed on an inner peripheral portion of the outer rotor and a sawtooth-shaped uneven surface formed on an outer peripheral portion of the inner rotor. The embedded magnet type motor, wherein the sandwiching portion is formed. 3. The size of adjacent concavo-convex surfaces forming the V-shaped concave portion of the saw-toothed concavo-convex surface of the outer rotor according to claim 2, An embedded magnet type motor characterized in that it is larger than the dimension of the adjacent uneven surface forming the V-shaped convex portion of the uneven surface. 4. The embedded structure according to claim 2, wherein the magnets sandwiched by the sandwiching portions of the inner rotor and the outer rotor are arranged so as to be inclined with respect to the circumferential direction of the rotor core. Built-in magnet type motor. 5. An embedded magnet type in which a sandwiching portion for sandwiching a magnet is formed at a facing portion of an outer rotor and an inner rotor having a rotor core having a two-divided structure, and the magnet is disposed at the sandwiching portion. A method of assembling a motor, wherein the magnet is disposed in the sandwiching portion of either the outer rotor or the inner rotor, and the outer rotor and the inner rotor are rotated in a direction in which a gap between the facing portions becomes wider. In this state, the inner rotor is inserted into the outer rotor, and the outer rotor and the inner rotor are rotated in a direction in which the gap between the facing portions becomes narrower, so that the magnet is brought into close contact with the sandwiching portion. The embedded magnet type motor assembling method characterized in that. 6. An inner rotor is inserted into an outer rotor having a rotor core having a two-divided structure, and one of the outer rotor and the inner rotor is rotated in a direction in which a facing interval between the outer rotor and the inner rotor is widened, and the outer rotor and the inner rotor are rotated. A magnet is inserted into a sandwiching portion that sandwiches a magnet formed in a portion facing the rotor, and after the magnet is inserted into the sandwiching portion, one of the outer rotor and the inner rotor is opposed to each other by a gap. The method of assembling an embedded magnet type motor according to claim 1, wherein the magnet is brought into close contact with the sandwiching portion of the inner rotor and the outer rotor by rotating the magnet in a direction in which the magnet becomes narrower.