JPH06245458A - Flat brushless motor - Google Patents

Abstract

PURPOSE:To provide a flat brushless motor of small cogging torque and high torque. CONSTITUTION:A flat brushless motor comprises a first stator 14 where six stator winding 16 is arranged on an iron plate yoke and a second stator 17 where six stator windings 19 are arranged on an iron plate yoke 18. Disc permanent magnets 12 and 13 each magnetized alternately with four N poles and four S poles in conformity to the first stator 14 and the second stator 17, respectively, are mounted in phase on an iron plate yoke 11 and fixed on a rotary shaft 10 to constitute a rotor 9. The first and second stators 14 and 17 are fixed on the main body via a motor housing so that their stator windings 16 and 19 may displace by 1/2 pitch of arrangement angle. Applying this motor for drive of a VTR reel can reduce wow flutter and jitter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat type brushless motor.

[0002]

2. Description of the Related Art As electronic devices such as video tape recorders have become lighter, thinner, shorter, smaller, and have higher functions, various brushless motors used in electronic devices have small size, high torque,
A low cogging motor is required. In order to satisfy this requirement in the conventional flat type brushless motor, (1) the magnetic coercive force of the disk permanent magnet constituting the rotor is increased. (2) Increase the number of stator windings that form the stator. (3) Increase the applied current to the stator winding. It is necessary to take measures such as.

However, (1) An increase in the magnetic coercive force of the disk permanent magnet causes an increase in the cogging torque at the same time. (2) Increasing the number of windings of the stator winding increases the loss of magnetic flux, and thus the required torque cannot be earned. (3) The increase of the applied current is limited by the capability of the driving IC. For these reasons, it has been very difficult for the conventional flat type brushless motor to meet the requirements for small size, high torque, and low cogging.

FIG. 4 shows an example of a conventional flat type brushless motor, and FIG. 4 (A) shows the internal structure thereof.
(B) shows the arrangement of the fan-shaped flat windings that form the stator,
FIG. 4C shows a magnetized state of the disk permanent magnets that form the rotor. In FIG. 4, a stator 1 comprises a plurality of, for example, six flat windings 3 arranged on an iron plate yoke 2, and is fixed to a main body via a motor outer casing 4. Also,
The rotor 5 is composed of a disk permanent magnet 8 provided on an iron plate yoke 7 fixed to the rotating shaft 6. The disk permanent magnet 8
Are magnetized into a plurality of N poles and S poles (eight poles alternately), and when a voltage is applied to the flat winding 3, a rotational moment is generated in the disk permanent magnet 8.

By the way, of the motor torque, the cogging torque is a forward / reverse torque shown in FIG. 2 (D) which is generated by the correlation between the reluctance change of the winding 3 and the magnetic field distribution of the permanent magnet 8. It is a torque ripple (torque fluctuation) that is felt when the motor shaft is rotated from the outside when the motor is not energized.
When it is used for driving a TR reel, a smaller value is desirable because it affects wow and flutter in audio and jitter in video.

[0006]

SUMMARY OF THE INVENTION In view of the above problems, the present invention is to provide a flat brushless motor having a small cogging torque and a high torque.

[0007]

SUMMARY OF THE INVENTION The present invention provides a flat brushless motor having a stator comprising a plurality of stator windings and a rotor comprising a plurality of pairs of forward and reverse magnetized disk permanent magnets. At least two stages of a combination of a stator composed of a plurality of stator windings and a rotor composed of a plurality of pairs of forward and reverse magnetized disk permanent magnets are superposed, and at least one of the stator windings of one stator is wound. The stator winding of the other stator or the forward / reverse magnetization of the other rotor is shifted by a predetermined angle with respect to the forward / reverse magnetization of the rotor to reduce the cogging torque, and a flat brushless motor suitable for driving the reel is configured. To do.

[0008]

FIG. 1 shows an embodiment of the brushless motor of the present invention. The rotor 9 is provided on both sides of an iron plate yoke 11 fixed to the rotating shaft 10, and as shown in (C) of FIG. 1, a first N-pole and an S-pole are alternately magnetized into eight poles. Consisting of a disk permanent magnet 12 and a second disk permanent magnet 13,
The first and second disk permanent magnets 12 and 13 are closely fixed to the iron plate yoke 11 so that the same poles face each other.

Further, the embodiment of the brushless motor of the present invention includes the first and second stators. First
As shown in FIG. 1B, the stator 14 of the fan-shaped winding 1 is arranged in a plurality, for example, six, on the iron plate yoke 15.
6 and is installed at a position facing the first disk permanent magnet 12. The second stator 17 is shown in FIG.
As shown in FIG. 7, six fan-shaped windings 19 are arranged on the iron plate yoke 18 similarly to the first stator 14, and the fan-shaped windings 19 are installed at positions facing the second disk permanent magnet 13.

Both of the stators 14 and 17 are fixed to the set body through the motor outer casing 20. At this time, the arrangement of the fan-shaped windings is 1/1 as shown in FIGS. 1 (B) and 1 (D).
Install by shifting 2 pitches.

When the fan-shaped windings are arranged so as to be displaced by 1/2 pitch in this manner, the cogging torque characteristic generated by the first disk permanent magnet 12 and the fan-shaped winding 16 is shown in FIG. 2A. The second disk permanent magnet 1 shown in FIG.
3 and the cogging torque characteristic generated by the fan-shaped winding 19 deviate from each other.

The cogging torque characteristic of the motor as a whole is a cogging torque characteristic with a low torque ripple as shown in (C) in which the cogging torque characteristic (A) and the cogging torque characteristic (B) are added. In the case of this embodiment, the cogging torque characteristic is half that of the conventional flat type brushless motor, as shown in FIG.
It is possible to realize a flat type brushless motor that rotates smoothly with low torque ripple.

When such a flat brushless motor of the present invention is used to drive a reel motor of a VTR or the like, it is possible to obtain an electronic device having a small effect on wow and flutter and jitter as described above.

In the case of the above-mentioned embodiment, the pitch of the windings constituting the stator is shifted as shown in FIGS. 1B and 1D, but as another embodiment, FIG. 3A and FIG. (B)
As shown in, even if the magnetizing switching positions of the N and S poles of the disk permanent magnets 12 and 13 are displaced, the same effect can be obtained. In this case, the arrangement of the fan-shaped windings of the stators 14 and 17 is the same, and the disk permanent magnet 1 is
In order to prevent the magnetic fields generated by 2 and 13 from affecting each other, it is necessary to use a magnetic shield plate instead of the iron plate yoke 11.

[0015]

According to the present invention, the cogging torque can be at least half that of the conventional flat type brushless motor, and at least two disk permanent magnets can be used. At least twice as much torque as that of the conventional flat type brushless motor can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing cogging torque characteristics of the present invention and a conventional example.

FIG. 3 is an explanatory diagram of another embodiment.

FIG. 4 is an explanatory diagram of a conventional example.

[Explanation of symbols]

 9 rotor 12 1st disk permanent magnet which comprises a rotor 13 2nd disk permanent magnet which comprises a rotor 14 and 17 stator 16 1st fan-shaped winding which comprises a stator 19 2nd which comprises a stator Fan-shaped winding

Claims (2)

[Claims] 1. A flat brushless motor comprising a stator composed of a plurality of stator windings and a rotor composed of a plurality of pairs of forward and reverse magnetized disk permanent magnets, comprising a plurality of stator windings. At least two layers of a combination of a stator and a rotor composed of a plurality of pairs of forward and reverse magnetized disk permanent magnets are superposed on each other, and the stator winding of one stator or the forward and reverse magnetization of one rotor is magnetized. On the other hand, a flat brushless motor characterized in that the stator winding of the other stator or the normal and reverse magnetization of the other rotor are shifted by a predetermined angle. 2. The flat brushless motor according to claim 1, which drives a reel of the tape recording / reproducing apparatus.