JP2003284301A - Motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a slimmed motor which produces high torque with a simple structure. <P>SOLUTION: When three-phase electric signals are given to respective coils of a U phase, V phase and W phase, a force for stabilizing a magnetic path is generated between the inner-periphery side facing portion 16a and the outer- periphery side facing portion 17a of a magnetic field development unit 15 of each of the phases, and a low magnetism resistance portion 22 of a rotor so that the rotor 20 is rotated. This motor 10 needs no permanent magnets, thus slimming the motor. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor mounted on a flexible disk device or the like, and more particularly to a motor which can be made thin.

[0002]

2. Description of the Related Art FIG. 8 is a sectional view showing a conventional brushless motor used in a flexible disk device or the like.

In this motor 1, a rotating shaft 3 is rotatably supported by a bearing member 4 at the center of a thin plate-shaped base 2 on the stator side. On the base 2, a plurality of magnetic field generating units 5 are arranged around the rotating shaft 3 at a constant pitch. Each magnetic field generating unit 5 is composed of a vertically extending pole-shaped magnetic core 6 and a coil 7 wound around the magnetic core 6.

A disk-shaped rotor 8 is fixed to the rotating shaft 3, and a ring-shaped permanent magnet 9 is fixed to the lower surface of the rotor 8. The surface of the permanent magnet 9 facing the base 2 is a magnetized surface, and the N pole and the S pole are alternately formed in the circumferential direction on the magnetized surface.

The magnetic field generating units are divided into three groups, and the drive currents are applied to the three groups of magnetic field generating units at different timings. By this three-phase drive, the magnetic poles of the permanent magnet 9 are sequentially attracted to each magnetic field generation unit 5, whereby the rotor 8 rotates.

[0006]

However, in the above conventional motor 1, the permanent magnet 9 is provided on the lower surface of the rotor 8,
Since the magnetic field generating unit 5 is located below the magnetic field generating unit 5 with a space therebetween, there is a problem in that the thickness of the entire motor 1 cannot be reduced.

Further, in the motor 1 having the above-mentioned structure, since the magnetic flux generated in each magnetic field generation unit 5 does not form a magnetic circuit (closed magnetic path), the magnetic flux generated from the magnetic field generation unit 5 is large and the rotor 8 is rotated. Therefore, there is a problem in that the efficiency of conversion into a driving force is low and that the leakage magnetic field easily causes noise to various electric circuits outside the motor 1.

The present invention is intended to solve the above-mentioned conventional problems, and an object of the present invention is to provide a motor which can be made thin and has a small leakage magnetic field.

[0009]

According to the present invention, there is provided a rotor which rotates about an axis, and a stator which faces the rotor with a gap therebetween in the axial direction of the axis. A plurality of magnetic field generating units having coils,
In the motor arranged in the circumferential direction of rotation of the rotor, in the rotor, a plurality of low magnetic resistance portions are arranged at intervals in the circumferential direction via high magnetic resistance portions having a higher magnetic resistance than this, Each of the magnetic field generation unit, the inner peripheral side facing portion that faces the rotor on the inner peripheral side near the axis,
An outer peripheral side facing part facing the rotor on the outer peripheral side away from the axis, and the magnetic flux induced by the coil has the inner peripheral side facing part, the low magnetic resistance part, and the outer peripheral side facing part. When a drive current having a phase different from each other is applied to the coils of the different magnetic field generation units, the low magnetic resistance portion is added to the magnetic field generation unit to which the drive current is applied. It is characterized in that the rotor can be rotated by being sequentially attracted.

In the present invention, the low magnetic resistance portion provided in the rotor is attracted to the magnetic field generation unit to which the drive current is applied, and the magnetic path is stabilized by the magnetic field generation unit and the low magnetic resistance unit. The rotor is rotated by using the force. Therefore, it is not necessary to provide a permanent magnet on the rotor, the motor can be made thinner, and the rotor can be made lighter. Further, since the magnetic circuit (closed magnetic path) is formed by the magnetic field generation unit and the low magnetic resistance portion, there is little leakage magnetic field from the magnetic field generation portion to the outside, the utilization efficiency of the magnetic field is high, and Less likely to give noise to electric circuits.

In each magnetic field generation unit, a line connecting the center of the inner peripheral side facing portion and the center of the outer peripheral side facing portion is inclined with respect to a normal line extending in the radial direction from the center of the shaft. It is preferable.

That is, in each magnetic field generation unit, it is preferable that either the inner peripheral side facing portion or the outer peripheral side facing portion is displaced in the rotational direction of the rotor.

With this structure, the rotor can be efficiently given a force in the rotational direction, and the drive torque of the motor can be increased.

Further, it is preferable that a center line that bisects the circumferential width of the low magnetic resistance portion of the rotor is inclined with respect to a normal line extending from the center of the shaft in the radial direction.

In this case, the center of the inner peripheral side facing portion and the center of the outer peripheral side facing portion of the magnetic field generation unit may be located on a normal line about the axis, but the inner peripheral side facing portion may be located. It is preferable that the line connecting the center of the center and the center of the outer peripheral side facing portion is inclined with respect to the normal line. In this case, it is further preferable that the inclination direction between the centers and the inclination direction of the low magnetic resistance portion in the magnetic field generation unit are the same direction.

By tilting the center line of the low magnetic resistance portion with respect to the normal line, the force applied to the rotor in the rotational direction can be increased and the drive torque of the motor can be increased.

For example, at least the surface of the rotor facing the stator is made of a magnetic material, and the magnetic material portion is provided with a plurality of notches at intervals in the circumferential direction. Is the high magnetic resistance portion, and the portion where the magnetic material is left is the low magnetic resistance portion.

Alternatively, a magnetic material having a high magnetic permeability may be arranged at intervals in the circumferential direction on a rotor having a non-magnetic property or a high magnetic resistance, and the magnetic material portion may be a low magnetic resistance portion. .

Further, the plurality of magnetic field generation units are divided into three groups, the drive current is given to the same group of magnetic field generation units at the same timing, and the drive current is supplied to the three groups of magnetic field generation units. It is possible to perform three-phase driving in which the timings are changed and sequentially applied.

[0020]

1 is a plan view showing an embodiment of a motor of the present invention, FIG. 2 is a sectional view taken along the line II-II of the motor of FIG. 1, FIG. 3A is a plan view of a rotor, and FIG. It is sectional drawing of a rotor. The motor shown in FIGS. 1 and 2 is a reluctance motor 10 that converts a magnetic attraction force into a rotational force.

A motor 10 shown in FIGS. 1 and 2 has a stator (stator) 11 and a disk-shaped rotor (rotor) 20.
have. The stator 11 is provided with a substrate 12 made of a magnetic material. The rotor 20 is also made of a magnetic material. These substrate 12 and rotor 2
0 is a silicon steel plate obtained by adding silicon to a ferromagnetic material such as iron, cobalt, or nickel, or an electromagnetic steel plate having improved magnetic properties by controlling the crystal orientation of the steel plate and the width of magnetic domains. .

A bearing member 14 is provided in the center of the base plate 12 of the stator 11, and the rotating shaft 13 is rotatably supported by the bearing member 14. A tubular portion 20a is integrally formed in the central portion of the rotor 20 by drawing, and the tubular portion 20a is fixed to the rotary shaft 13.

In the stator 11, a plurality of magnetic field generating units 15 are provided on the upper surface of the substrate 12. Figure 4
FIG. 3 is a partial perspective view showing one magnetic field generating unit 15 exaggeratedly. The magnetic field generation unit 15 has an inner peripheral coil C1 located on the side closer to the rotary shaft 13 and an outer peripheral coil C2 located on the side farther from the rotary shaft 13. Inner circumference coil C
An inner circumference side magnetic core 16 is provided at the center of 1, and an outer circumference coil C
An outer peripheral magnetic core 17 is provided at the center of 2.

In the present embodiment, the upper end surface of the inner peripheral side magnetic core 16 is the inner peripheral side facing portion 16a, and the outer peripheral side magnetic core 1
The upper end surface of 7 is an outer peripheral side facing portion 17a. The lower surface of the rotor 20 has the inner peripheral facing portion 16a.
And the outer peripheral side facing portion 17a via a minimum gap G.

The winding directions of the inner circumference coil C1 and the outer circumference coil C2 are opposite to each other, and the inner circumference coil C1 and the outer circumference coil C2 are connected in series. When a drive current is applied to one magnetic field generation unit 15 at a predetermined timing,
As shown in FIG. 4, a path of a magnetic flux φ1 connecting the inner peripheral side facing portion 16a, the rotor 20 and the outer peripheral side facing portion 17a, and a magnetic flux φ2 connecting the inner peripheral side magnetic core 16, the substrate 12 and the outer peripheral side magnetic core 17.
And the magnetic field generating unit 15 forms a magnetic circuit (closed magnetic circuit).

In the magnetic field generation unit 15, the inner magnetic core 16 and the outer magnetic core 17 do not necessarily have to be provided, and the inner coil C1 and the outer coil C2 are formed on the substrate 12 made of a magnetic material. The structure may be provided. In this case, the inner peripheral coil C1 functions as the inner peripheral side facing portion, and the outer peripheral coil C2 functions as the outer peripheral side facing portion.

By providing the inner magnetic core 16 and the outer magnetic core 17, the magnetic flux density of the magnetic fluxes φ1 and φ2 can be increased. On the other hand, by adopting a structure in which the inner circumference side magnetic core 16 and the outer circumference side magnetic core 17 are not provided, the inner circumference coil C1 and the outer circumference coil C2 can be made thin, and the height of the motor can be reduced. When the magnetic core is not provided, the inner coil C1 and the outer coil C2 can be formed by printed coils. This printed coil can be formed by etching a thin film of a conductor provided on an insulating film (printed circuit board) on the surface of the substrate 12 into a planar spiral shape.

The magnetic field generating unit 15 includes the rotating shaft 13
The magnetic field generating units 15 are provided at a constant distance from the axis center O and at a constant pitch in the circumferential direction. In the illustrated embodiment, 18 magnetic field generating units 15 are provided at a pitch of 20 degrees.

As shown in FIG. 5A, in each magnetic field generating unit 15, an imaginary line connecting the center of the area of the inner peripheral side facing portion 16a and the center of the area of the outer peripheral side facing portion 17a is L1-.
Let L1 be a virtual circle having an arbitrary radius from the axis O of the rotary shaft 13 and be D. When the intersection of the virtual line L1-L1 and the virtual circle D is K1 and the normal line passing from the axis O of the rotary shaft 13 through the intersection K1 is R1, the virtual line L1-L1 is It is inclined by a predetermined angle β1 with respect to the normal R1.

In the illustrated embodiment, the drive rotation direction of the rotor 20 is counterclockwise (α direction), and in one magnetic field generating unit 15, the center of the inner peripheral side facing portion 16a is the outer peripheral side facing portion 17a. The magnetic field generating unit 15 is arranged so as to be tilted in the rotation direction with respect to the normal line so as to be shifted in the rotation direction (α direction) from the center of.

This motor 1 is a three-phase drive system,
The individual magnetic field generation unit 15 is divided into three groups, and
A drive current is applied to all the magnetic field generation units 15 of one set at the timing shown by the U phase in FIG. The drive current is applied to the other magnetic field generating units 15 of the other set at the timing indicated by the V phase, and the remaining magnetic field generating units 15 of the remaining one set.
Is supplied with a drive current at the timing indicated by the W phase.

In FIG. 1, six magnetic field generation units 15 to which a drive current is given at the U-phase timing are U1, U2 and
It is indicated by U3, U4, U5 and U6. Further, the magnetic field generation units 15 to which the drive current is applied at the V-phase timing are indicated by symbols V1, V2, V3, V4, V5 and V6, and the magnetic field generation unit 15 to which the drive current is applied at the W-phase timing is W.
1, W2, W3, W4, W5, W6.

As shown in FIGS. 1, 3 and 5, the rotor 20 is provided with a plurality of notches 21 formed by rectangular elongated holes (slits). Each of the notches 21 is formed equidistant from the axis O of the rotary shaft 13 and at a constant pitch in the circumferential direction.

In this embodiment, the cutout portion 21 is a space, and this portion has a high resistance to magnetic flux, so that the cutout portion 21 is a high magnetic resistance portion 23. The magnetic material forming the rotor 20 is present in the portion sandwiched between the adjacent notches 21 and 21. The magnetic flux easily passes through this portion, and the resistance to the magnetic flux is low, and the low magnetic resistance portion 22 is formed. In this embodiment, the low magnetic resistance portion 22 is
It is provided in some places.

In order to rotate the rotor with the three-phase drive current, when the number of the low magnetic resistance portions 22 is N and the number of the magnetic field generating units 15 is n, (n−N) / n is 1/3
Should be a relationship.

As shown in FIG. 3A, the notch portion 21 is formed with a constant inner width dimension, and the inner peripheral end portion 2 thereof is formed.
1a is formed to be inclined with respect to the normal line so as to be oriented in the rotational direction (α direction) with respect to the outer peripheral side end 21b. Further, the low magnetic resistance portion 22 has an inner peripheral side end portion 22a.
The outer peripheral end 22b has a fan shape with a wider width.

Letting L2-L2 be a virtual center line connecting the centers of the tangential width dimension at each location of the low magnetic resistance portion 22, this virtual center line L2-L2 is the center O of the rotary shaft 13. It is inclined with respect to the normal line that extends radially from. That is, as shown in FIG. 5A, the virtual center line L2-L
Let K2 be the intersection of 2 and the virtual circle D, and the axis center O
When a normal line connecting the intersection point K2 and the intersection point K2 is R2, the virtual center line L2-L2 is an angle β2 with respect to the normal line R2.
Just leaning.

Here, the angle β1 and the angle β2 indicating the inclination of the magnetic field generating unit 15 have the same direction, and β1> β2.

The basic operating principle of the motor 10 will be described.

In FIG. 4, the cutout portion 21, that is, the high magnetic resistance portion 23 of the rotor 20 is located on the inner peripheral side facing portion 16a and the outer peripheral side facing portion 17a of one of the magnetic field generating units 15, The low magnetic resistance portion 22 is separated from the inner peripheral side facing portion 16a and the outer peripheral side facing portion 17a.

At this time, when a drive current is applied to the inner peripheral coil C1 and the outer peripheral coil C2 of the magnetic field generating unit 15 shown in FIG. 4, the inner peripheral side facing portion 16a and the outer peripheral side facing portion 17 are provided.
In order to stabilize the path of the magnetic flux φ1 that crosses a, a force that guides the low magnetic resistance portion 22 onto the inner circumferential side facing portion 16a and the outer circumferential side facing portion 17a acts. That is, if the low magnetic resistance portion 22 covers the inner circumferential side facing portion 16a and the outer circumferential side facing portion 17a, the inner circumferential side facing portion 16a, the low magnetic resistance portion 22 and the outer circumferential side facing portion 17a are connected. The magnetic path of the magnetic flux φ1 is stably formed between
Such stabilizing force acts on the rotor 20. A rotational torque T is generated in the rotor 20 by this force.

Therefore, in FIG. 1, U-phase drive currents simultaneously applied to the inner peripheral coils C1 and the outer peripheral coils C2 of the sets U1 to U6, the inner peripheral coils C1 and the outer peripheral coils C2 of the sets indicated by V1 to V6, respectively. Drive current of V phase simultaneously given to the inner peripheral coils C1 of the groups W1 to W6
By sequentially switching the W-phase drive currents applied to the outer peripheral coil C2 and the outer peripheral coil C2, the stabilizing force described in FIG. 4 is applied to the low magnetic resistance portion 22 in order. As a result, the rotor 20 is continuously driven to rotate in the α direction.

FIG. 6 shows the drive currents of the U phase, V phase and W phase. In FIG. 6, the current phase is shown on the upper side of the diagram, and the rotation angle of the rotor is shown on the lower side.

The drive current of each phase has a pulse-like current in one direction (+ direction) and a current in the other direction (-direction).
The phase is 240 ° out of phase with the U phase, and the W phase is 240 ° out of phase with the V phase. The amount of phase shift in each phase is 2/3 of one cycle.

FIG. 5A shows the time when the rotation angle becomes 15 degrees in FIG. At this time, since the low magnetic resistance portion 22 reaches right above the magnetic field generation unit 15 of V1 and the magnetic path is stabilized, the inner peripheral coil C1 and the outer peripheral coil C of V1 at this point.
2 is energized. At this point of time, the energization of the magnetic field generation unit 15 of W6 is continued, and the energization of the magnetic field generation unit 15 of U1 is started.

FIG. 5B shows the time when the rotation angle reaches 25 degrees in FIG. At this time, the low magnetic resistance portion 22 reaches right above the magnetic field generating unit 15 of U1 and the magnetic path is stabilized, so that at this time, the inner peripheral coil C1 and the outer peripheral coil C of U1.
2 is energized. At this point, the energization of the magnetic field generation unit 15 of V1 is continued, and the energization of the magnetic field generation unit 15 of W6 is started.

Therefore, at the timing shown in FIG.
By setting the V-phase and W-phase currents, the rotor 2
0 can be driven in the α direction.

Further, in this embodiment, as shown in FIGS. 5A and 5B, in each magnetic field generation unit 15, the inner circumferential side facing portion 16a and the outer circumferential side facing portion 17a are circumferentially arranged with respect to the normal line. It is arranged so as to be displaced. Therefore, when the rotor 20 rotates, one facing portion (the outer circumferential side facing portion 17a in the illustrated embodiment) faces the low magnetic resistance portion 22 first, and after the magnetic flux enters the low magnetic resistance portion 22, A force for pulling the low magnetic resistance portion 22 on the other facing portion (the inner circumferential side facing portion 16a) to stabilize the magnetic path acts. Therefore, the utilization efficiency of the magnetic field is good, and high torque can be generated.

Further, by increasing the inclination of the angle β1 with respect to the normal line R1 of the virtual center line L1-L1 of the magnetic field generation unit 15 shown in FIG. 5A, the magnetic path is formed between the magnetic field generation unit 15 and the low magnetic resistance portion 22. It is possible to make it easier to direct the force for stabilizing in the circumferential direction of rotation. And in this case,
Since the virtual center line L2-L2 of the low magnetic resistance portion 22 is inclined by β2 with respect to the normal line R2, the low magnetic resistance portion 22 is provided on the outer peripheral side facing portion 17a of the magnetic field generating unit 15 which is inclined as described above. After reaching, the low magnetic resistance portion 22 can immediately reach the inner peripheral side facing portion 16a, and the low magnetic resistance portion 2
The magnetic path formed in 2 is easy to stabilize. Therefore, the utilization efficiency of the magnetic field is good, and high torque is easily obtained.

FIG. 7 is an enlarged sectional view showing another embodiment of each magnetic field generating unit. In the motor shown in FIG.
The substrate 32 of the stator is made of a non-magnetic material and is, for example, a printed circuit board. Each magnetic field generation unit 35 is
It has a U-shaped magnetic material core (magnetic core) 36, and a coil 37 is wound around the core 36. Then, one end surface of the core 36 is an inner peripheral side facing portion 36a, and the other end surface is an outer peripheral side facing portion 36b. The line connecting the centers of the inner peripheral side facing portion 36a and the outer peripheral side facing portion 36b is inclined as shown in FIG. 5A, and the structure of the rotor 20 is the same as that of the embodiment shown in FIG.

The notch 21 of the rotor 20 may be filled with a non-magnetic material such as synthetic resin to form a high magnetic resistance portion. Alternatively, layers or plates of a magnetic material may be arranged on the lower surface of the rotor 20 made of a non-magnetic material so as to be circumferentially spaced apart, and the portion of the magnetic material may be a low magnetic resistance portion.

[0052]

As described above, according to the present invention, since it is not necessary to use a permanent magnet, the motor can be made thin. It is also possible to generate high torque with a simpler configuration.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a motor of the present invention,

2 is a sectional view taken along line II-II of FIG.

FIG. 3A is a plan view of the rotor, B is a cross-sectional view of the rotor,

FIG. 4 is a perspective view showing a magnetic field generation unit and a low magnetic resistance part;

5A and 5B are partial plan views showing a relationship between a magnetic field generation unit and a rotor when the rotor rotates,

FIG. 6 is a chart showing timings of U-phase, V-phase, and W-phase drive currents;

FIG. 7 is a sectional view showing a magnetic field generation unit according to another embodiment,

FIG. 8 is a sectional view of a conventional motor,

[Explanation of symbols]

10 motors 11 Stator (stator) 12 substrates 13 rotation axis 14 Bearing member 15 Magnetic field generation unit 16a Inner peripheral facing portion 17a Outer peripheral facing portion 20 Rotor 21 Notch 22 Low magnetic resistance part 23 High magnetic resistance part 35 Magnetic field generation unit 36 core 37 coils

Claims (5)

[Claims] 1. A plurality of magnetic field generating units, each of which has a rotor that rotates about an axis and a stator that faces the rotor with a gap in the axial direction of the axis, and each of which has a coil. However, in the motor arranged in the circumferential direction of rotation of the rotor, in the rotor, a plurality of low magnetic resistance portions are arranged at intervals in the circumferential direction via high magnetic resistance portions having a higher magnetic resistance than this. Each of the magnetic field generation units has an inner peripheral side facing portion that faces the rotor on the inner peripheral side near the shaft and an outer peripheral side facing portion that faces the rotor on the outer peripheral side away from the shaft. Then, the magnetic flux induced by the coil can form a magnetic path that passes through the inner peripheral side facing portion, the low magnetic resistance portion, and the outer peripheral side facing portion. Drives with different phases When the flow is given, the magnetic field generating unit drive current is given by the low-reluctance portion is successively attracted, motor, wherein the rotor is rotatable operation. 2. In each magnetic field generation unit, a line connecting the center of the inner peripheral side facing portion and the center of the outer peripheral side facing portion is
The motor according to claim 1, wherein the motor is inclined with respect to a normal line extending in the radial direction from the center of the shaft. 3. The motor according to claim 1, wherein a center line that bisects a circumferential width of the low magnetic resistance portion of the rotor is inclined with respect to a normal line extending radially from the center of the shaft. . 4. The rotor has at least a surface facing the stator formed of a magnetic material, and the magnetic material portion is provided with a plurality of notches at intervals in the circumferential direction. 4. The motor according to claim 1, wherein is the high magnetic resistance portion, and the portion where the magnetic material is left is the low magnetic resistance portion. 5. The plurality of magnetic field generation units are divided into three groups, the drive currents are given to the same group of magnetic field generation units at the same timing, and the drive currents are supplied to the three groups of magnetic field generation units. 5. The motor according to claim 1, wherein the motor is capable of three-phase driving in which the timing is sequentially changed.