JPH08340667A - Magnet motor - Google Patents

Abstract

PURPOSE: To provide a magnet motor which facilitates the improvement of the torque ripple. CONSTITUTION: A magnet motor has a rotor magnet 1, a stator core 2 which is composed of teeth 2a-2d and there tip parts 2f-2i and coils 3a-3d which are wound on the teeth 2a-2d. The coils 3a-3d are so wound as to have the polarities of the adjacent teeth 2a-2d different from each other. The rotor magnet 1 has pole pairs which are composed of a pair of first poles 1b and 1c having relatively large circumferential angles and a pair of second poles 1d and 1e having relatively small circumferential angles. The first and second poles 1b-1e are provided at such an angle ratio as to eliminate the counter-torque components of partial torques generated in the tip parts 2f-2i practically.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a fan motor, a CD-
The present invention relates to improvements in small and simple magnet motors such as ROM spindle motors.

[0002]

2. Description of the Related Art Conventionally, in a brushless magnet motor such as a fan motor in which torque ripple is not a problem, one Hall element is used with the number of rotor magnets and stator tips or slots being about four.
The two coils are alternately energized and rotated. In this case, when a magnetic field symmetrical with respect to the normal and reverse rotation directions is formed, a starting dead point is generated for the reason described below.Therefore, by providing a notch in a part of the tip, the magnetic pole of the magnet and the stator tip are provided. The method of avoiding the dead center by deflecting the cogging torque generated during the period is generalized.

FIG. 2 shows a cross section of a magnetic circuit of such a conventional fan motor. In the figure, 1 is a sine wave quadrupole magnetized annular rotor magnet, 1a is a magnetized zero-cross portion, and 1b is a rotor yoke. Reference numeral 2 denotes four protruding teeth 2a, 2b, 2c, 2d and a bearing hole 2e.
In the stator, which is formed by laminating dozens of lamination cores obtained by punching an isotropic silicon steel strip having a magnet, an outer rotor type magnetic circuit is constituted by the magnet 1 and the stator 2. Teeth 2a, 2b, 2c, 2
and d, which have taps 2f, 2g, 2h, and 2i, respectively, face the inner peripheral surface of the magnet 1, and are teeth 2b and 2d.
Has its central angle indicated by a chain line 2bd. Coils 3a, 3b, 3c, 3d are wound around the outer periphery of each tooth, and 3a-3c, 3b-3d are connected in series. An air gap 4 is formed between the inner circumference of the magnet 1 and the outer circumference of each tap, and a hole sensor 5 is mounted on a non-display base plate in the gap between the tip 2f and the adjacent tap 2g.

The tip 2f has a portion 2f1 protruding toward the magnet side and a portion 2f2 retracted from the magnet, and the other tips 2g, 2h and 2i are set to have the same shape. Therefore, with respect to the tip 2f, the magnetization center N of the facing magnet 1 is the tooth 2a.
Of the tip 2f is more strongly attracted to the projecting side 2f1 of the tip 2f, and as a result, the position of the zero cross 1a moves to the position shown in the figure and the magnetic field is linked to the sensor 5. In response, when an output voltage is generated in the sensor 5, this output voltage is signal-processed and given to the drive circuit of FIG. 3A as an on / off signal. That is, a conduction signal is applied to one of the bases of the semiconductor switches 6a and 6b that form the power stage of the drive circuit, and the semiconductor switch 6a
One of the windings 6b and 6b is closed, and an exciting current is supplied to the coil 31 formed of the windings 3a-3c or the coil 32 formed of the windings 3b-3d, whereby a rotating magnetic force is generated between the magnet 1 and each tip. The rotor rotates. Thereafter, the output voltage of the sensor alternates with the rotation of the rotor magnet, so that both switches are alternately opened and closed to continue the rotation of the rotor.

By the way, in the magnetic circuit of FIG. 2, if there is no deformation such as an overhanging portion 2f1 or a receding portion 2f2 on the tip, the center of the magnetic pole of the magnet only faces and faces the center line of each tooth. At this time, since the zero cross 1a is located on the center line of the gap between the tips, the magnetic flux does not interlink with the sensor 5, so that no current can be obtained. Depending on the drive circuit, there is a drive circuit that automatically energizes when no signal arrives for a certain period, but even if energization is obtained, in such a positional relationship, the magnet and tip are radial. It only attracts or repels the direction and does not start the rotor.
Therefore, in the conventional magnetic circuit, it is indispensable to deviate the rotor magnet with respect to the circumferential direction by notching the shape of each tip outer circumference facing the inner circumference of the magnet 1.

Regarding the reason why the rotor is declined due to the notch of the tip, in the case of FIG. 2, the rotor magnet 1
Since the radial length of the gap 4 formed so as to face the inner circumference of the air gap is asymmetric with respect to the rotation direction, the magnetic resistance of the air gap and therefore its attraction force are also asymmetric. Therefore, the magnetic pole of the rotor magnet 2 is attracted by this asymmetrical cogging torque generated between the rotor magnet 2 and each tip, and is stabilized at the moved position as compared with the case where there is no notch.

The structure shown in FIG. 2 is widely used because of its simple and low cost, but on the other hand, it has the following drawbacks. Primarily,
The gap length of a certain angle has a notch in the tip, so that the wave ripples with rotation, so that a vibration component is mixed in the magnetomotive force and the torque ripple increases. Secondly, this torque ripple not only directly causes electromagnetic vibration and noise, but also vibrates the mechanical parts of each part of the motor, resulting in an unavoidable increase in noise vibration level. Thirdly, the notch shape increases the average gap length and raises the air gap magnetic resistance, which causes a decrease in the rotating torque, and therefore the excitation current must be increased, and therefore the efficiency is inevitably reduced.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art and to provide a novel magnet motor capable of improving the torque ripple itself, which has been impossible by the new magnetic circuit. Is to provide.

[0009]

SUMMARY OF THE INVENTION In the present invention, a rotor magnet having a plurality of magnetic poles and a plurality of teeth arranged at intervals in the circumferential direction are provided, and the tips of the plurality of teeth are provided. A magnet motor including a stator core each provided with a tip extending in the circumferential direction, an excitation winding wound around the plurality of teeth, and a drive circuit for energizing the excitation winding. The tips of the individual tips and the rotor magnet have a substantially equal spacing in the circumferential direction, and the excitation winding is wound around the plurality of teeth such that the polarities of adjacent teeth are different. Cage,
The rotor magnet has a first magnetic pole having a relatively large circumferential angle and a second magnetic pole having a relatively small circumferential angle. The circumferential angles of the first and second magnetic poles are equal to each other. The ratio is set to substantially eliminate the generation of the reverse torque component in the partial torque generated in the plurality of tips.

[0010]

In the magnet motor of the present invention, the rotor magnet is composed of the first magnetic pole having a relatively large circumferential angle and the second magnetic pole having a relatively small circumferential angle. The circumferential angles of the first magnetic pole and the second magnetic pole are set to a ratio that substantially eliminates the reverse torque component in the partial torques generated in the plurality of tips. Therefore, the reverse torque component is not substantially generated in the plurality of tips, the efficiency of the motor can be improved, and the cogging torque and the torque ripple can be reduced.

[0011]

1 shows a cross section of a magnetic circuit according to a first embodiment of the present invention. In the figure, the symbols of each part are the same as those in FIG. The magnet 1 is a radially-oriented anisotropic rubber ferrite magnet magnetized in a sine wave, and is magnetized in four poles so that the N poles and the S poles are alternately arranged in the embodiment. The circumferential angle of the magnetic pole will be described later. The stator is formed of a lamination core 2 in which 13 isotropic silicon steel strips are laminated. The stator core 2 includes four teeth 2 arranged at substantially equal intervals in the circumferential direction.
a, 2b, 2c, 2d, and these teeth 2a, 2
Tips 2f, 2g, 2 extending in the circumferential direction (the direction of rotation of the motor and the opposite direction) are provided at the tips of b, 2c, 2d.
h and 2i are provided respectively. For example, teeth 2a
The tip 2f has an upstream portion 2f1 extending in the rotation direction of the rotor magnet 1 and a downstream portion 2f2 extending in the opposite direction to the rotation direction. Are substantially equal to the angle of. The intervals between the outer peripheral surfaces of the tips 2f, 2g, 2h, 2i and the inner peripheral surface of the rotor magnet 1 are set to be substantially equal in the circumferential direction.

Coils 3a, 3b, 3c and 3d as excitation windings are wound around the teeth 2a, 2b, 2c and 2d. In the embodiment, the coils 3a, 3b, 3c, 3d are composed of an integral coil, and are wound so that the magnetic poles of adjacent teeth are opposite to each other. For example, Teeth 2
The coil 3a wound around a is clockwise, the coil 3b wound around the tooth 2b is counterclockwise, the coil 3c wound around the tooth 2c is clockwise, and the coil 3d wound around the tooth 2d is counterclockwise. It is wound clockwise.

Next, the magnetic pole width of the rotor magnet 1 will be described. In the embodiment, the pair of first magnetic poles 1 is used.
b and 1c have a relatively large circumferential angle, for example, 105
It is set to every. The angle of the pair of second magnetic poles 1d and 1e in the circumferential direction is relatively small, and is set to, for example, 75 degrees. In this motor, the pair of first magnetic poles 1b, 1
c and a pair of second magnetic poles 1d and 1e constitute a magnetic pole set, and the pair of magnetic poles 1d and 1c are provided inside the pair of magnetic poles 1b and 1c.
and the circumferential angle of the first magnetic poles 1b and 1c is
By setting the angle of the second magnetic poles 1d and 1c in the circumferential direction to about 1.4 times, the effects described later can be achieved.

The magnetic force generated in the individual magnetic poles upon energization between the rotor magnet 1 and the stator in the above-described motor has the pattern shown in FIG. That is, in the embodiment, the tip 2 of the teeth 2a, 2b, 2c, 2d is used.
The ratio of the circumferential angle of f, 2g, 2h, 2i to the circumferential angle of the slot defined between adjacent tips (in other words, the slot gap) is 5: 1 (5 times).
Is set to When the rotor magnet 1 moves in the rotation direction indicated by the arrow with respect to the stator having such a configuration, it is possible to substantially eliminate the generation of the reverse torque component in each magnetic pole 1b, 1c, 1d, 1e of the rotor magnet 1. In FIG. 4, each magnetic pole 1b, 1c of the rotor magnet 1,
The V-shaped display near the display magnetic poles (symbol N or S in the drawing) in 1d and 1e indicates the rotor magnet 1
The magnitude and direction of the electromagnetic force acting between the stator and the stator are shown. <Character-shaped display indicates that the electromagnetic force acts in the protruding direction of the tip. And, on both sides of the display magnetic pole
When the character display is shown, the action of the driving electromagnetic force is relatively large, and when the <character display is shown on one side of the display magnetism, the driving electromagnetic force is medium and the display magnetic pole When the <character display is not shown in the vicinity, the driving electromagnetic force does not substantially act.

Further, each magnetic pole 1b of the rotor magnet 1,
The indications in the upstream portions of the rotational directions 1c, 1d, and 1e indicate the magnitude and direction of the cogging torque. Similar to the case of the driving electromagnetic force, the <shaped display indicates that the cogging torque acts in the protruding direction of the tip. When <character display is shown, cogging torque acts, and when “-” is displayed instead of <character display, cogging torque does not substantially act.

As a circuit of this motor, for example, FIG.
The thing shown in (b) can be used. That is, it is composed of four drive transistors 7a, 7b, 8a, 8b,
Between the drive transistors 7a and 8b, the coil 3 (a, b,
drive transistors 8a, 7b by connecting one ends of c, d)
The other end of the coil 3 is connected between the two. When supplying the coil 3 with a current in a predetermined direction indicated by an arrow, the drive transistors 7a and 7b are energized. Thus, the current from the power supply flows through the drive transistor 7a, the coil 3 and the drive transistor 7b in the direction indicated by the arrow. On the other hand, when the current is supplied in the opposite direction to the above, the drive transistors 8a and 8b are energized. Thus, the current from the power supply is sent through the drive transistor 8a, the coil 3 and the drive transistor 8b in the direction opposite to the arrow.

In such a motor, when the current is supplied to the coil 3 as described above, the rotor magnet 1 has the first magnetic pole and the second magnetic pole, so that the rotor magnet 1 repeats acceleration and reduction in a certain direction. Rotate at a predetermined speed. When the rotor magnet 1 is thus rotated in the predetermined direction, as can be understood from FIG. 4, the reverse torque component of the driving magnetic force is not substantially generated in each magnetic pole 1b, 1c, 1d, 1e of the rotor magnet 1, so that the rotor magnet 1 The rotation of 1 becomes smooth, and the cogging torque can be suppressed and the torque ripple can be reduced. A dedicated magnet may be provided to switch the current to the coil 3.

In the embodiment of FIG. 1, an isotropic material is used for the stator core 2, but in order to improve the starting characteristics, an anisotropic material having a certain directionality, for example, directional silicon steel is used. Bands can be used. For the configuration and the effect of using the anisotropic material, refer to the specification and drawings of the patent application (name: magnet motor) filed by the applicant on May 12, 1995.

The stator core is not limited to the lamination core, but may be used in a magnetic circuit that applies an electromagnetic force acting on the surface of a stator tip formed of a punched steel plate, such as an inductor motor. The same can be applied to the other case by adopting a plurality of tip shapes.

FIG. 5 shows a second embodiment of the motor according to the present invention. In FIG. 5, in the second embodiment, the stator 102 has twelve teeth 102a to 102l arranged at substantially equal intervals in the circumferential direction, and the tips of these teeth 102a to 102l are Respectively,
Tips 104a to 104l extending in the circumferential direction are provided. A rotor magnet 106 is rotatably arranged outside the stator 102. The rotor magnet 106 has the same number as the teeth 102a to 102l.
The tooth 10 has two magnetic poles 108a to 108l.
The intervals between the outer peripheral surfaces of the tips 104a to 104l of 2 to 102l and the inner peripheral surface of the rotor magnet 106 are substantially equal in the circumferential direction.

In the second embodiment, the rotor magnet 106 has three magnetic pole sets. Magnetic poles 108a, 1
08b, 108c and 108l constitute a first magnetic pole set, and the magnetic poles 108c and 108l constitute a first magnetic pole having a relatively large circumferential angle, and the magnetic poles 108b and 108c.
However, a second magnetic pole having a relatively small circumferential angle is formed,
A pair of second magnetic poles are arranged inside the pair of first magnetic poles. Further, the magnetic poles 108d and 108g (or 108
h, 108k) constitutes the first magnetic pole of the second set (or the third set), and the magnetic poles 108e, 108f (or 108i,
108j) constitutes the second magnetic pole of the second set (or the third set). Also in this example, the circumferential angle of the first magnetic pole is set to 1.4 times the circumferential angle of the second magnetic pole, the first magnetic pole is 35 degrees, and the second magnetic pole is 25 degrees. It has become.

Even in such a configuration, as will be easily understood, the rotational torque generated between the tips 104a to 104l of the teeth 102a to 102l and the magnetic poles 108a to 108l of the rotor magnet 106 is substantially zero. It becomes either (zero) or the rotation direction (forward direction), so that the torque component in the reverse direction can be eliminated. Therefore, the motor efficiency can be increased, or a magnet material having a low maximum magnetic flux density can be used. Further, in this case, it is possible to avoid the synchronization of all the magnetic poles and all the tips, so that the vibration frequency can be dispersed. It should be noted that such an effect can be obtained also in various combinations such as a multi-slot configuration in which a magnetic circuit is multiplied by an integer, or the above tooth width ratio 1/2 is changed to 2/3, and the cogging torque and the torque ripple are obtained. Can be reduced. Incidentally, in order to further reduce the cogging torque, a commutating pole may be appropriately provided.

In the motor of the second embodiment, the rotation can be controlled by the circuit shown in FIG. 6, for example. That is, the coil is a single coil for all the teeth 102a to 102a.
In this embodiment, for example, the coil 1 wound around the teeth 102a to 102d can be wound in series with 2l.
12a (teeth 102a-cw (clockwise), 102
d-ccw (counterclockwise), 102c-cw, 102d
-Ccw) and the coil 112b (teeth 102e-cw, 102f) wound around the teeth 102e to 102h.
-Ccw, 102g-cw, 102h-ccw) and the coil 112c wound around the teeth 102i to 102l.
(102i-cw, 102j-ccw, 102k-c
w, 1021-ccw) are connected in parallel. When thus connected, a power supply voltage is applied to each coil 112a, 112b, 112c, and each coil 112a, 112b, 1c
The applied voltage of 12c can be effectively maintained high, and the generated magnetic field can be increased. Therefore, such connection can be applied when driven at a relatively low voltage.

When the drive transistors 114a and 114b are energized, the current from the power supply is sent through the drive transistors 114a, 112a 112b and 112c and the drive transistor 114b in the direction indicated by the arrow.
On the other hand, when the drive transistors 116a and 116b are energized, the current from the power supply is
a, the coils 112a, 112b, 112c, and the driving transistor 116b are fed in the direction opposite to the arrow.

FIG. 7 shows a third embodiment of the magnet motor according to the present invention. In the third embodiment, the stator core 202 has twelve teeth 204a to 204l arranged at intervals in the circumferential direction.
4a to 204l are provided with tips 206a to 20
6l is provided. A rotor magnet 208 is arranged outside the stator core 202, and the structure of the rotor magnet 208 is substantially the same as that of the second embodiment shown in FIG.

In the third embodiment, the stator core is made of an anisotropic silicon steel plate having one direction, and the specific direction of this silicon steel plate is a straight line 205 (a straight line extending substantially vertically in FIG. 7). Is substantially 10 degrees in the counterclockwise direction with reference to
It extends substantially 10 degrees in the counterclockwise direction with reference to.

The angles of the tips 206a to 206l in the circumferential direction correspond to the ratio of the angles of the rotor magnet 208. That is, tip 206a,
206d, 206e, 206h, 206i, 206l
Constitutes the first tip having a relatively large circumferential length, and the remaining tips 206b, 206c, 206f, 2
06g, 206j, and 206k constitute a second tip having a relatively small circumferential length. The tips 206a to 206l are arranged in the circumferential direction such that the pair of second tips are arranged inside the pair of first tips, and the angle of the first tip in the circumferential direction is the second.
Is set to 1.4 times the circumferential angle of the tip.

The other structure of the third embodiment may be the same as that of the second embodiment. In the third embodiment, the same effect as that of the second embodiment is achieved, and since the grain-oriented silicon steel sheet is used, the starting characteristic can be improved.

Although the embodiments of the magnet motor according to the present invention have been described above, the scope of application of the present invention is not limited to the configurations of these embodiments, and is applicable to various motors and drives using anisotropic materials. It can be widely applied without departing from the technical base. For example, a stator with mixed directionality and multi-direction, a multi-directional stator such as bidirectional, a magnetic circuit with a further change in the number of poles and slots, a magnet with multiple orientations, an inner rotor type magnet It is possible to selectively use a circuit, various coil connections including parallel connection, a method in which the present invention is applied only to activation, and driving is performed in multiple phases during rotation. Further, although the magnet is rotated in the embodiment, it can be applied to a motor of a type in which the magnet is stationary and the exciting coil is rotated.

[0030]

According to the present invention, the magnetic poles of the rotor magnet are composed of two kinds of magnetic poles having different rotational angles, and the angles of these two kinds of magnetic poles are reversed in the partial torque generated in the tip of the stator. Since the torque component is set so as not to substantially occur, the cogging torque, and thus the torque ripple, can be reduced or eliminated. In particular, in a single-phase motor, it is possible to use a low-class magnet material by further improving the motor efficiency.

[Brief description of drawings]

FIG. 1 shows a cross section of a magnetic circuit of a first embodiment of a magnet motor according to the present invention.

FIG. 2 shows a cross section of a magnetic circuit of a conventional fan motor.

FIG. 3 shows power stages of various single-phase excitation drive circuits.

FIG. 4 shows a property of a partial torque generated in each tip of the motor according to the first embodiment.

FIG. 5 shows a cross section of a magnetic circuit of a second embodiment of a magnet motor according to the present invention.

FIG. 6 shows a power stage of a single-phase excitation drive circuit for a motor according to a second embodiment.

FIG. 7 shows a cross section of a magnetic circuit of a third embodiment of a magnet motor according to the present invention.

[Explanation of symbols]

 1 rotor magnet 2 stator core 2a to 2d teeth 2f to 2i tip 3a to 3d coil 5 magnet sensor

Claims (7)

[Claims] 1. A magnet having a plurality of magnetic poles and a plurality of teeth arranged at intervals in the circumferential direction, and tips at the tips of the plurality of teeth extending in the circumferential direction. A magnet motor including a core that is provided and is rotatable relative to the magnet, an excitation winding wound around the plurality of teeth, and a drive circuit for energizing the excitation winding. In the above, the intervals between the tip surfaces of the plurality of tips and the magnet are substantially the same in the circumferential direction, and the excitation winding is wound around the plurality of teeth so that the polarities of the adjacent teeth are different. The magnet has a first magnetic pole having a relatively large circumferential angle and a second magnetic pole having a relatively small circumferential angle, and the magnet has a circumferential circumference of the first and second magnetic poles. Angle of direction occurs in the plurality of tips The occurrence of reverse torque component in the minute torque is set to a ratio of substantially eliminate magnet motor, characterized in that. 2. The magnet has a magnetic pole set composed of four magnetic poles in which N poles and S poles are alternately arranged, and the magnetic pole set includes a pair of the first magnetic poles and a pair of the first magnetic poles. The magnet motor according to claim 1, wherein the magnet motor comprises two magnetic poles. 3. The pair of first magnetic poles of the pair of magnetic poles is arranged outside the pair of second magnetic poles in the circumferential direction.
The magnet motor described. 4. The magnet motor according to claim 2, wherein the magnet is composed of 1, 2 or 3 sets of the magnetic poles. 5. The magnet motor according to claim 1, wherein the circumferential angle of the first magnetic pole is 1.4 times the circumferential angle of the second magnetic pole. 6. The magnet motor according to claim 1, wherein the number of magnetic poles of the magnet is equal to the number of teeth of the plurality of teeth. 7. The core is made of a soft magnetic material having a specific directionality, and is fed from the magnet to the tips of the plurality of teeth when the excitation winding is not energized. 7. The magnet motor according to claim 1, wherein the magnetic flux is deflected to deflect the magnet in its rotation direction.