JP2001218393A - Permanent magnet electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem, where leakage flux is generated by adjacent permanent magnets, and the flux of the permanent magnets for contributing to the rotary drive of an electric motor is reduced when width tb of a bridge part is large, since a width tb of the bridge part cannot be set smaller than a thickness tr of a magnetic steel plate due to problems regarding strength and manufacture in a conventional permanent embedded rotor. SOLUTION: This permanent magnet electric motor is composed of a permanent magnet rotor, where a plurality of permanent magnets 2 that are provided at the outer periphery of a rotor core body in that a plurality of magnetic steel plates are laminated, are covered with a magnetic material pipe 3, and a stator that has a magnetic pole part that opposes the permanent magnet rotor for generating rotary flux. In this case, a tip surface 13 of the magnetic pole part has a curvature and is recessed in a direction opposite to the rotor, thus reducing the magnetic gap between the permanent magnet and the tip surface of the magnetic pole part by using the magnetic material pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor having a permanent magnet rotor for holding a permanent magnet by a holding pipe.

[0002]

2. Description of the Related Art A conventional permanent magnet rotor 21 having a permanent magnet embedded therein is formed by laminating a plurality of magnetic steel plates having slits for embedding a permanent magnet 22 into a laminated core body, and then forming the laminated core body. It was formed by embedding the permanent magnet 22. Since such a permanent magnet rotor holds the permanent magnet by the bridge portion of the laminated core body, the magnetic flux of the permanent magnet passes through the bridge portion, which is a magnetic steel plate, without being hindered, and Easy to flow. In such a configuration, the magnetic gap between the permanent magnet and the end face of the magnetic pole portion of the stator is smaller than that of the permanent magnet rotor in which the permanent magnet is covered with a nonmagnetic metal pipe, and the magnetic flux of the permanent magnet is effectively used. Can be used for

[0003]

However, the width tb of the bridge cannot be made smaller than the thickness tr of the magnetic steel sheet due to strength or manufacturing problems. Leakage magnetic flux is generated in the permanent magnet, and the magnetic flux of the permanent magnet that contributes to the rotation driving of the electric motor is reduced.

According to the present invention, by using a magnetic material as the permanent magnet holding pipe, the portion supported on the outer peripheral side of the permanent magnet can be made thin regardless of the thickness of the magnetic steel plate. An object of the present invention is to provide an efficient electric motor with a small air gap.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a permanent magnet rotor in which a plurality of permanent magnets disposed on the outer periphery of a rotor core body in which a plurality of magnetic steel sheets are laminated are covered with a magnetic pipe, and the permanent magnet rotor. And a stator having a magnetic pole portion that generates a rotating magnetic flux in opposition to the motor.The tip surface of the magnetic pole portion has a curvature, and is an electric motor that is concave with respect to the rotor. In addition, the magnetic gap between the permanent magnet and the tip surface of the magnetic pole portion can be reduced.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a permanent magnet rotor in which a plurality of permanent magnets disposed on the outer periphery of a rotor core body in which a plurality of magnetic steel sheets are laminated are covered with a magnetic pipe, and a permanent magnet rotor facing the permanent magnet rotor. And a stator having a magnetic pole portion that generates a rotating magnetic flux, the tip surface of the magnetic pole portion has a curvature, is an electric motor that is concave with respect to the rotor, and is made permanent by using a magnetic pipe. The magnetic gap between the magnet and the tip surface of the magnetic pole portion can be reduced. The distance between the tip end surface of the magnetic pole portion and the permanent magnet rotor is preferably substantially constant.

The relationship between the thickness tp of the magnetic pipe and the thickness tr of the magnetic steel plate forming the permanent magnet rotor is as follows.
If tp <tr, the magnetic gap can be further reduced, and an efficient permanent magnet motor can be provided. The thickness of the magnetic pipe may be 0.3 mm or less.

The resistance of the magnetic pipe is 115 μΩ ·
cm or more, generation of eddy current can be suppressed.

[0009]

(Embodiment 1) The permanent magnet rotor of this embodiment is
As shown in FIGS. 1 and 2, four arcuate permanent magnets 2 are arranged on the outer periphery of a laminated iron core 1 in which a plurality of magnetic steel sheets are laminated.
The length of the bow-shaped permanent magnet 2 in the stacking direction is shorter than the length of the laminated iron core 1 in the stacking direction, and the magnetic metal pipe 3 is shrink-fitted and pressed into the outer periphery of the bow-shaped permanent magnet 2.

The shrink-fitting press-fitting will be described in detail. First, the magnetic metal pipe 3 is heated, and the inner diameter of the magnetic metal pipe 3 is changed to the diameter of the permanent magnet rotor body in which the bow-shaped permanent magnet 2 is disposed on the laminated iron core 1. And shrink fit. Before the magnetic metal pipe 3 covers the whole of the permanent magnet rotor main body, the magnetic metal pipe 3 cools down, the diameter of the magnetic metal pipe 3 and the diameter of the permanent magnet rotor main body become the same, and the magnetic metal pipe 3 becomes the permanent magnet rotor. Shrink fitting is completed before covering the whole. When the diameters of the magnetic metal pipe 3 and the permanent magnet rotor main body become the same, the positioning of the magnetic metal pipe 3 is performed, the rear of the magnetic metal pipe 3 is pushed out, and the magnetic metal pipe 3 is permanently pressed by press fitting. Completely cover the magnet rotor body to complete the permanent magnet rotor. At the time of press-fitting, the magnetic metal pipe 3 has heat, so that the magnetic metal pipe 3 is easily inserted.

The laminated iron core 1 is provided with four clamp holes 6 having the same number of poles of the rotor, and these clamp holes are located at positions close to the center of the magnetic poles of the arcuate permanent magnet 2 in the circumferential direction.
One per pole is provided. Plate-shaped non-magnetic end plates 4 are provided on both end surfaces in the thickness direction of the laminated iron core 1, and the same number of holes are provided in positions corresponding to the clamp holes provided in the laminated iron core 1, and the laminated iron core 1 and the flat The clamp is integrally clamped through a clamp pin 5 penetrating through the non-magnetic end plate 4. The clearance t between the outer diameter of the flat non-magnetic end plate 4 and the inner diameter of the magnetic metal pipe 3 is 0.4 mm or less.

Even if the arc-shaped permanent magnet 2 is chipped during the assembly of the rotor, the gap t between the outer diameter of the flat non-magnetic end plate 4 and the inner diameter of the magnetic metal pipe 3 is 0.4 mm or less, so that the arc-shaped permanent magnet 2
Falling powder due to chipping does not scatter outside the rotor. By providing the clearance t, when the magnetic metal pipe 3 contracts, the stress of the magnetic metal pipe 3 can be applied to the permanent magnet without being hindered by the flat non-magnetic end plate 4.

The clamp holes 6 provided in the laminated iron core 1 are provided one by one in the circumferential direction at a position close to the center of the magnetic pole of the bow-shaped permanent magnet 2. Therefore, as shown in FIG. There is no hindrance to the flow of the magnetic flux inside, and the magnetic susceptibility such as the magnetic path does not deteriorate.

Such a permanent magnet rotor 11 is arranged in a distributed winding stator 12 as shown in FIG. 3, and the permanent magnet rotor rotates in synchronization with a rotating magnetic flux generated from the stator 12. . The front end surface 13 of the magnetic pole portion of the stator 12 (close to a plane in FIG.
That is, it has an arc shape on the opposite side of the permanent magnet rotor) and is concave in the opposite direction of the rotor. With such a shape, the distance between the permanent magnet 2 and the wire end surface 13 of the magnetic pole portion is kept substantially constant, and the magnetic flux distribution between the magnetic pole portion and the permanent magnet becomes uniform.

The permanent magnet rotor 11 of this embodiment uses the magnetic metal pipe 3 as a permanent magnet holding pipe, and the resistance of the magnetic metal pipe at this time is reduced by the resistance (1) of the conventional nonmagnetic pipe.
8-8 non-magnetic stainless steel tube: 72 μΩ · cm). Thus, the resistance of the magnetic metal pipe is 115 μΩ ·
cm or more, the generation of eddy current is small regardless of the magnetic material. That is, by using such a rotor, the permanent magnet rotor 11 and the stator 1
2 can reduce the air gap.

The thickness of the non-magnetic metal pipe is preferably smaller in order to suppress the leakage magnetic flux leaking from the adjacent arc-shaped permanent magnet.

Conventionally, as a means for preventing magnets from scattering, there has been a method of embedding magnets in an electromagnetic steel sheet. However, when the electromagnetic steel sheet is punched by a press, the bridge width is set to prevent the magnet from scattering. Is limited by the thickness of the sheet. Generally, the bridge width tb and the thickness tr of the electromagnetic steel sheet are td
Is the limit. On the other hand, in the present embodiment, since the magnetic metal pipe is not punched by a press, the thickness of the magnetic pipe can be reduced, and the thickness tp of the magnetic pipe is tp
By setting <tr, an effect superior to the method of embedding the magnet in the electromagnetic steel sheet can be obtained.

Further, the magnetic metal pipe 3 is connected to the arc-shaped permanent magnet 2.
By tightening the outer periphery of the magnet, the tightening of the bow-shaped permanent magnet is increased while reducing the thickness of the magnetic metal pipe. May be press-fitted or shrink-fitted.

FIG. 4 is a longitudinal sectional view of a permanent magnet rotor according to a second embodiment of the present invention. In addition to the first embodiment, a bent portion 7 is formed by bending both ends or one of the nonmagnetic metal pipes 21 (both ends in the figure) in the inner diameter direction, so that the clearance between the nonmagnetic metal pipe 21 and the flat nonmagnetic end plate 4 is reduced. . As a result, powder falling off due to the lack of the bow-shaped permanent magnet 2 is less likely to scatter outside the rotor. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

FIG. 5 is a longitudinal sectional view of a permanent magnet rotor according to a third embodiment. In addition to the first embodiment, balance correction weights 8 are attached to both sides or one side (one side in the figure) of the flat non-magnetic end plate 4 and are clamped integrally by the clamp pins 5. This eliminates the need for man-hours for attaching the weight in a separate step, and as a result, an assembly method can be easily obtained. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

(Embodiment 4) FIG. 6 is a longitudinal sectional view of a permanent magnet rotor according to Embodiment 4. In addition to the third embodiment, a non-magnetic end plate 9 with a weight, in which a flat non-magnetic end plate and a weight are integrated, is clamped integrally by a clamp pin 5 on the opposite side to which the weight 8 is mounted. Thereby, the man-hour for combining the flat non-magnetic end plate 4 and the weight 8 at the time of assembling the rotor can be omitted. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

[0022]

According to the present invention, by using a magnetic pipe, the magnetic gap between the permanent magnet and the tip of the magnetic pole portion can be reduced, and an efficient motor can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a rotor according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the rotor.

FIG. 3 is a sectional view of the electric motor.

FIG. 4 is a longitudinal sectional view of a rotor according to a second embodiment of the present invention.

FIG. 5 is a longitudinal sectional view of a rotor according to a third embodiment of the present invention.

FIG. 6 is a longitudinal sectional view of a rotor according to a fourth embodiment of the present invention.

FIG. 7A is a sectional view of a conventional permanent magnet rotor. FIG. 7B is a partial side view of the permanent magnet rotor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laminated iron core 2 Arched permanent magnet 3 Magnetic metal pipe

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hiroshi Murakami 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Terms (reference) 5H002 AA02 AB06 AE07 5H621 BB10 GA01 GA04 GA11 5H622 AA03 CA02 CA13 DD02 PP03 PP16

Claims (5)

[Claims] 1. A permanent magnet rotor in which a plurality of permanent magnets disposed on the outer periphery of a rotor core body in which a plurality of magnetic steel sheets are laminated is covered with a magnetic pipe, and a rotating magnetic flux is generated by facing the permanent magnet rotor. A permanent magnet motor comprising: a stator having a magnetic pole portion, wherein a tip end surface of the magnetic pole portion has a curvature and is concave with respect to the rotor. 2. The permanent magnet motor according to claim 1, wherein the distance between the tip end surface of the magnetic pole portion and the permanent magnet rotor is substantially constant. 3. The relationship between the thickness tp of the magnetic pipe and the thickness tr of the magnetic steel sheet forming the permanent magnet rotor is tp.
The permanent magnet electric motor according to claim 1, wherein <tr is satisfied. 4. The electric motor according to claim 3, wherein the thickness of the magnetic pipe is 0.3 mm or less. 5. The resistance of the magnetic pipe is 115 μΩ · cm.
The electric motor according to claim 1, which is as described above.