JPH05316673A - Outer-rotor type permanent magnet rotor - Google Patents

Abstract

(57) [Abstract] [Purpose] The number of difficult-to-machine field permanent magnet segments is halved compared to the conventional number, and the work of attaching field permanent magnets to the rotor is reduced, resulting in low cost production. An outer rotation type permanent magnet rotor having excellent properties is provided. In the outer rotation type permanent magnet rotor in which the permanent magnets 2 for magnetic field magnetized in the radial direction are attached to the inner surface in the circumferential direction of the yoke 1 at equal intervals, all the permanent magnets 2 for field magnetism are included. Are attached so that the same poles are oriented in the center direction, and by providing convex protrusions 3 between the field permanent magnets, the polarity opposite to the center direction of the field permanent magnets is provided on the protrusions 3. And a magnetic circuit that alternately generates N poles and S poles on the inner surface in the circumferential direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outer rotor permanent magnet rotor.

[0002]

2. Description of the Related Art A cross section of a conventional outer rotor permanent magnet rotor is shown in FIG. The abduction-type permanent magnet rotor of FIG. 5 is an example of an abduction-type permanent magnet rotor having six magnetic poles, and includes six field permanent magnets 2 and a soft magnetic material or a laminated soft magnetic material. And a yoke 1 formed of a magnetic steel plate. The field permanent magnet is magnetized in the radial direction and is attached to the inner surface in the circumferential direction at equal intervals using an adhesive so that the N poles and the S poles alternate with respect to the central axis direction.

[0003]

However, in the conventional outer rotation type permanent magnet rotor, the permanent magnets for the field magnet are arranged on the inner surface of the yoke 1 in the circumferential direction so that the N poles and the S poles are alternately arranged. The structure described above has a problem that a large number of arc-shaped field permanent magnets 2 that are difficult to process are required. Further, sticking a large number of permanent magnets 2 for field magnetism leads to lower efficiency of rotor assembly work, which is a factor of cost increase.

An object of the present invention is to eliminate the drawbacks of the prior art, reduce the number of arc-shaped permanent magnets 2 for a field, increase the efficiency of assembly work, and reduce the cost. A permanent magnet rotor is provided.

[0005]

In the outer rotor permanent magnet rotor according to the present invention, a yoke is formed of a soft magnetic material or a plurality of laminated soft magnetic steel plates, and the inner surface in the circumferential direction of the yoke is Field permanent magnets magnetized in the radial direction are attached at equal intervals, and all the field permanent magnets are attached with the same pole in the central axis direction. By forming the yoke shape between the permanent magnets for projecting into a convex shape and providing a protrusion, a magnetic pole different from the magnetic pole on the surface in the central axis direction of the field magnet is generated at that portion, so that the N pole is formed on the inner surface in the circumferential direction. It is characterized by having a magnetic circuit that alternately generates south poles.

[0006]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of an outer rotor permanent magnet rotor showing an embodiment of the present invention. An outer rotor permanent magnet rotor having six magnetic poles will be described. The outer rotor permanent magnet rotor of the present invention is composed of a yoke 1 in which a soft magnetic material or a plurality of soft magnetic steel plates are laminated, and a field permanent magnet 2, and three field permanent magnets 2. Is magnetized in the radial direction. All the three permanent magnets 2 for field magnets are S poles in the center direction and N poles in the yoke direction, and all the same poles are attached so as to face the center direction. A convex projection 3A is formed between the field permanent magnets 2,
The field magnets and the protrusions are arranged alternately in the circumferential direction. The height of the protrusion is the same as that of the field permanent magnet, and the surfaces of the field permanent magnet and the protrusion in the center direction are on an arc having the same radius. The arc length of the protrusion is equal to the arc length of the field permanent magnet, and the gap between the field permanent magnet and the protrusion has an appropriate gap.

Next, the magnetic circuit structure of the present invention will be described in detail. FIG. 2 is an enlarged sectional view of the outer rotor permanent magnet rotor of the present invention, and arrows 4, 5A and 5B in the figure show the flow of magnetic flux from the field permanent magnet 2. Since the magnetic flux 4 on the center side surface of the field magnet 2 flows from the center toward the outer side as shown in the figure, that portion becomes the S pole. Further, the magnetic flux 5A on the surface opposite to the central axis direction passes through the yoke 1 as shown in the figure, and the magnetic flux 5B from the adjacent field permanent magnet.
Due to the repulsive action of the same pole as, the flow from the outside toward the center toward the protrusion 3A. Therefore, the protrusion 3A generates the N pole. As a result, the rotor has a north pole S on the inner surface in the circumferential direction.
The poles will be generated alternately. This makes it possible to construct a magnetic circuit similar to the case where the field permanent magnets are magnetized alternately in the circumferential direction only by magnetizing the field permanent magnets in the same direction.

Next, the gap distance between the permanent magnet for field and the protrusion will be described. FIG. 3 is a cross-sectional view of an outer rotor permanent magnet rotor according to the present invention when the gap distance is small. The arrow 6 in the figure indicates the flow of magnetic flux generated from the field magnet. When the gap distance between the field permanent magnet 2 and the protrusion 3A is short, a leakage magnetic flux 7 is generated and the motor is rotated. Therefore, the effective magnetic flux toward the center cannot be sufficiently obtained.
Therefore, the gap distance between the permanent magnet for field and the protrusion must be at least larger than the thickness of the permanent magnet for field.

FIG. 4 is a cross-sectional view of the outer rotor permanent magnet rotor according to the present invention when the protrusions have different shapes. When the distance between the field permanent magnet and the protrusion is small or when the leakage magnetic flux is large, the protrusion shape 3B shown in the figure is used. As shown in the figure, the protrusion has a chamfered corner, so the magnetic flux from the field permanent magnet reduces the leakage to the adjacent protrusion and causes the motor to rotate. Therefore, it becomes possible to sufficiently obtain the effective magnetic flux 6 toward the center.

In this embodiment, an example in which the field permanent magnet is attached with the S pole facing the center is described, but the magnetization direction of the field permanent magnet 2 is changed to change the N pole to the center. Needless to say, the same effect can be obtained by sticking with the face facing.
Further, in this embodiment, there are three field permanent magnets and three protrusions.
Although the number of magnetic poles composed of 6 pieces has been described as an example, if the number of poles is a multiple of 2, the same effect can be obtained in any case of the outer rotor type permanent magnet rotor. . Further, a rare earth magnet having a high energy density is most suitable for the permanent magnet for the field magnet, but the same effect can be obtained by using various magnets such as a ferrite magnet and an alnico magnet.

[0012]

As described above, the outer rotor permanent magnet rotor according to the present invention has the same pole of the permanent magnet for the field magnet attached in the direction of the central axis, and has a yoke shape between the field magnets. By the structure that is molded in a convex shape, compared with the conventional abduction rotor,
It is possible to reduce the number of permanent magnets for field that are difficult to process. Along with this, since the attachment of the permanent magnet for the field is half that of the conventional method, the working efficiency is increased, the cost is low, and the productivity is excellent.

[Brief description of drawings]

FIG. 1 is a sectional view of an outer rotor permanent magnet rotor of the present invention.

FIG. 2 is an enlarged cross-sectional view of an outer rotor permanent magnet rotor of the present invention.

FIG. 3 is a cross-sectional view of an outer rotation type permanent magnet rotor according to the present invention when the gap distance is small.

FIG. 4 is a cross-sectional view of the outer rotor permanent magnet rotor according to the present invention when the protrusions have different shapes.

FIG. 5 is a sectional view of a conventional outer rotation type permanent magnet rotor.

[Explanation of symbols]

1 yoke 2 permanent magnet for field magnet 3A, 3B protrusion 4, 5A, 5B, 6 flow of magnetic flux generated by permanent magnet for field 7 leakage flux

Claims (1)

[Claims] 1. A yoke is formed of a soft magnetic material or a plurality of laminated soft magnetic steel plates, and a permanent magnet for field magnetized in a radial direction is equidistantly formed on the inner surface in the circumferential direction of the yoke. In the abduction type permanent magnet rotor attached,
All the field permanent magnets are pasted with the same pole in the central axis direction, and the same number of convex protrusions as the number of field magnets are provided between the field permanent magnets. A magnetic circuit for alternately generating N-poles and S-poles on the inner surface in the circumferential direction by generating a polarity opposite to the polarity of the surface in the central axis direction of the permanent magnet for the field in the part. Convertible permanent magnet rotor.