JPH088766B2 - Brushless motor - Google Patents

Description

The present invention relates to a brushless motor used for driving a small fan or the like.

[Conventional technology]

In a conventional brushless motor of this type, as shown, for example, in Japanese Examined Patent Publication No. 60-42700, a winding is directly wound around a slot of a stator core in which punched steel sheets are laminated to form a stator, and such a stator is used for a rotor. I am trying to rotate.

However, such a configuration has a problem that it is difficult to insulate the winding from the stator core and to wind the winding around the slot of the stator core, and it is difficult to automate the assembly. Therefore, the applicant of the present invention, as already filed as Japanese Patent Application No. 61-276084, provides a rotor equipped with a magnet rotatably coaxially with a bobbin around which a winding is wound, while A plurality of magnetic poles that can be excited based on the windings of the rotor are provided, and the magnetic poles are arranged so as to face the magnets of the rotor to rotate the rotor. This makes assembly easy and easy automation. I tried to be.

(Problems to be solved by the invention) However, in such a brushless motor, it may be difficult to self-start the rotor depending on the arrangement state of the magnetic poles. The present invention aims to solve such problems.

[Means for solving problems]

In order to solve such a problem, the present invention has a cylindrical magnetic core, and a bobbin around which two windings are wound is attached to the outer periphery of the magnetic core. A bearing is provided on the circumference, and the rotating shaft of a disk-shaped rotor provided with a magnet is rotatably supported by the magnetic core through the bearing, and both ends of the magnetic core are outside of both ends of the bobbin. One end of the magnetic core is provided with a disc-shaped flange projecting toward the outer periphery of the magnetic core, and one cylindrical magnetic pole body surrounding the bobbin is attached to the outer periphery of the flange. At the other end of the core, another flat plate-shaped magnetic pole body disposed inside the opening of the cylindrical magnetic pole body is attached, and the opening edge portion of the cylindrical magnetic pole body and the flat plate shape are attached. A plurality of magnetic poles are formed at the end of each magnetic pole body, and these magnetic poles are centered around the rotation axis of the rotor. The magnetic poles of one magnetic pole body and the magnetic poles of the other magnetic pole body are alternately arranged along the circumferential direction of the magnet, and are arranged on the outer peripheral side of the magnet. The magnetized polarity is detected by a position detection element, and the rotor is rotated by controlling energization of the winding through an electronic circuit based on the detection, and each magnetic pole of each magnetic pole body is Is formed in a fan shape centering on the rotation center axis of the rotor, and the width of the angular spread of the fan in each magnetic pole of the one magnetic pole body is the width of the angular spread of the fan in each magnetic pole of the other magnetic pole body. Different from the above, each magnetic pole of the other magnetic pole body arranged between the magnetic poles of the one magnetic pole body is arranged at a position deviated in the rotational direction of the rotor from the middle of each other. It is a thing.

[Action]

A reluctance torque (cogging torque) having a waveform shown in FIG. Also, by switching the energization of the two windings, an electromagnetic torque having a waveform shown in FIG. Therefore, at the time of energization, as shown in FIG. 7C, the driving torque having the waveform of the reluctance torque and the electromagnetic torque is obtained. As can be seen from the waveform of the drive torque, there is no position where the drive torque is always generated and the drive torque becomes zero, that is, there is no dead point regardless of the rotation angle of the rotatable rotor. Therefore, even if the rotor is stopped at any position, it can be self-started.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.
It will be described with reference to the drawings.

In the figure, reference numeral 1 denotes a bobbin formed of an electrically insulating material, and two windings 2 are wound around the bobbin 1 by a bi-fara winding.
A cylindrical magnetic core 3 made of a magnetic material is fitted and fixed in the center hole of the bobbin 1, and the rotary shaft 4 is provided inside the magnetic core 3.
Is inserted, and the rotating shaft 4 is rotatably supported via a bearing 5. A disc-shaped yoke 6 made of a magnetic material is horizontally attached to the upper end of the rotary shaft 4, and a ring-shaped magnet 7 is attached to the lower surface of the yoke 6 with an adhesive or the like. Rotor 8
Is configured. As shown in FIG. 4, the magnet 7 has N poles and S poles alternately arranged in quarters along the circumferential direction.
The poles are magnetized.

The upper and lower ends of the magnetic core 3 project outward at both ends of the bobbin 1, and the lower end of the magnetic core 3 is formed with a disc-shaped flange 3a that projects to the outer peripheral side. The magnetic core 3 has a first magnetic pole body 1 and a second magnetic pole body 1 each made of a magnetic material.
0.11 is installed. The first magnetic pole body 10 is the bobbin 1.
And is magnetically connected to the magnetic core 3 by being joined to the outer periphery of the flange 3a of the magnetic core 3 by means such as caulking or press fitting, and the second magnetic pole body 11 is formed in a flat plate shape. The magnetic core 3 is engaged with the outer periphery of the upper end of the magnetic core 3 by means such as caulking or press fitting to be magnetically connected to the magnetic core 3. The first cylindrical magnetic pole body 10 integrally has a pair of magnetic poles 10a.10b facing each other at the peripheral edge of the opening at the upper end, and these magnetic poles 10a.10b are arranged below the magnet 7 and They are spaced apart and face each other. The second flat magnetic pole body 11 has magnetic poles 11a.11b at both ends thereof.
Are arranged between the magnetic poles 10a and 10b of the first magnetic pole body 10 and face the magnet 7.

A position detecting element (hall element) 14 for detecting the rotational position of the rotor 8 is provided on the upper end surface of the bobbin 1 so as to face the magnet 7. Further, on the lower end surface of the bobbin 1, an electronic circuit board 15 having an electronic circuit for controlling energization of the winding 2.2 according to the output of the position detecting element 14 is provided.

Then, if the pole of the magnet 7 facing the position detecting element 14 is the N pole, one winding 2 of the bi-farer winding wound on the bobbin 1 is energized by the control of the electronic circuit of the electronic circuit board 15. , Magnetic poles 11a.11b are N poles, and magnetic poles 10a.10b are S poles.
If the pole of the magnet 7 which is excited to the pole and conversely faces the position detecting element 14 is the S pole, the other winding 2 of the bi-fara winding wound around the bobbin 1 is energized and the magnetic poles 11a and 11b are S-shaped. The magnetic poles 10a and 10b are excited to the N pole, and the rotor 8 is rotated by the repulsion and the suction action.

Each magnetic pole 10a.10b of the first and second magnetic pole body 10.11 and
As shown in FIG. 1, 11a.11b are formed in a fan shape with the rotation axis 4 as the center. The width of the spread angle of the fan (hereinafter, referred to as an angle width) will be described.
Angle width of the magnetic poles 10a.10b of the second magnetic pole body 11a.1
The angular width of 1b is different, and the angular width of one magnetic pole 10a of the first magnetic pole body 10 is different from the angular width of the other magnetic pole 10b. For example, the angular width of one magnetic pole 10a of the first magnetic pole body 10 is 85 °, the angular width of the other magnetic pole 10b is 71 °, and the angular width of each magnetic pole 11a.11b of the second magnetic pole body 11 is 45 °. Is.
The magnetic poles 11a and 11b of the second magnetic pole body 11 are the same as those of the first magnetic pole body 1.
The zero magnetic poles 10a and 10b are deviated in the rotational direction of the rotor 8 from the middle of the magnetic poles 10a and 10b, and the magnetic poles 11a and 11b and the magnetic pole 10a are arranged at an angle of 71 °. Then, the other magnetic pole 10b of the first magnetic pole body 10 and the second magnetic pole body 11
The position sensing element 14 is arranged between the other magnetic pole 11b and the magnetic pole 11b at a position adjacent to the magnetic pole 10b.

With such a configuration, a reluctance torque (cogging torque) having a waveform shown in FIG. Also, by switching the energization of the two windings 2.2, an electromagnetic torque having the waveform shown in FIG. Therefore, at the time of energization, as shown in FIG. 7C, a wave torque having a composite waveform of the reluctance torque and the electromagnetic torque can be obtained. As can be seen from the waveform of this drive torque, even if the rotatable rotor 8 is at any rotation angle position,
A drive torque is always generated in a fixed direction, and the drive torque is 0
There is no dead point, that is, Therefore, even if the freely rotatable rotor 8 is stopped at any rotation angle position, it can be self-started. Further, in order to improve efficiency, it is preferable that the magnetic resistance of the magnetic circuit is as small as possible. Therefore, in the case of four poles as in the present embodiment, the angular width of the poles is preferably close to 90 °. In this embodiment, the angle width of the pole is optimally set to obtain a predetermined reluctance torque without making the angle width of the pole so small.

FIG. 6 shows another embodiment of the present invention.
The angular width of the magnetic poles 11a and 11b of 11 is equal to the magnetic pole 10 of the first magnetic pole body 10.
The angle width of a.10b is made larger so as to have the same relationship as in the above embodiment.

The present invention is not limited to the four-pole structure as in the above-described embodiment, but can be applied to any 2n (n is a positive integer) pole structure.

〔The invention's effect〕

As described above, according to the present invention, even if the rotatable rotor is at any rotation angle position, a driving torque in a fixed direction is generated, and the rotor can always be self-started.

[Brief description of drawings]

1 is a plan view showing an embodiment of the present invention, FIG. 2 is a perspective view of the same in an exploded state, FIG. 3 is a sectional view taken along line III-III of FIG. 2, and FIG. 5 is a perspective view showing a torque generation state, and FIG. 6 is a plan view showing another embodiment of the present invention. 2 ... Winding, 3 ... Magnetic core, 7 ... Magnet, 8 ... Rotor, 10.11 ... Magnetic pole body, 10a.10b.11a.11b ... Magnetic pole, 14
…… Position detection element.

Claims (2)

[Claims] 1. A magnet having a cylindrical magnetic core, a bobbin around which two windings are wound is mounted on the outer circumference of the magnetic core, and a bearing is provided on the inner circumference of the magnetic core. A rotary shaft of a disk-shaped rotor provided with is rotatably supported by the magnetic core via the bearing, and both ends of the magnetic core project outward on both ends of the bobbin, and one of the magnetic cores A disc-shaped flange that projects to the outer peripheral side is provided at the end of, and one cylindrical magnetic pole body that surrounds the bobbin is attached to the outer periphery of this flange, and the other end of the magnetic core, Another flat plate-shaped magnetic pole body disposed inside the opening of the cylindrical magnetic pole body is attached, and a plurality of magnetic pole bodies are provided at the opening edge portion of the cylindrical magnetic pole body and the end portion of the flat pole body. Magnetic poles are formed, and these magnetic poles are arranged on the outer peripheral side of the rotation axis of the rotor, and To face at a distance from each other in data of the magnet,
The magnetic poles of one magnetic pole body and the magnetic poles of the other magnetic pole body are alternately arranged along the circumferential direction of the magnet, and the polarity magnetized by the magnet is detected by a position detection element, and based on this detection, the The rotor is rotated by controlling energization to a winding through an electronic circuit, wherein each magnetic pole of each magnetic pole body is formed in a fan shape around a rotation center axis of the rotor, and The width of the angle of spread of the fan in each magnetic pole of the magnetic pole body is different from the width of the angle of spread of the fan in each magnetic pole of the other magnetic pole body, and is arranged between the magnetic poles of the one magnetic pole body. A brushless motor characterized in that each magnetic pole of the other magnetic pole body is arranged at a position deviated in the rotational direction of the rotor from the middle thereof. 2. The brushless motor according to claim 1, wherein one magnetic pole body and the other magnetic pole body each have a pair of magnetic poles.