JP2002084720A - Spindle motor and disc driving device provided therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spindle motor of less noise with a thin configuration high-speed operation. SOLUTION: This spindle motor comprises a rotor hub 20 supported in such a way as to be rotatable freely via a bearing, an inside rotor magnet 52 fixed on the mounting part at the inside circumferential side of the rotor hub 20, an outside rotor magnet 54 fixed on the mounting part at the outside circumferential side of the rotor hub 20, a bracket 18, an inside stator 48 fixed on the mounting part at the inside circumferential side of the bracket 18, and an outside stator 50 fixed on the mounting part at the outside circumferential side of the bracket 18. The inside and outside stators 48, 50 are fixed to the bracket 18 by offsetting each other by a factor of a given angle to the rotational direction of the rotor hub 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor for rotating a disk or the like and a disk drive provided with the spindle motor.

[0002]

2. Description of the Related Art A spindle motor used in a disk drive device or the like is a brushless type motor, and noise reduction is one of the important research themes. The so-called switching noise occupies a large part of the noise component of the brushless motor. Switching noise forms the main electromagnetic noise of the brushless motor. The mechanism of switching noise is caused by a level of structural vibration caused by the exciting drive force or torque when the drive current supplied to the coils of the stator is switched from one phase to another.

[0003] Switching of the drive current produces an "unstable torque" which is generally characterized as torque ripple. If the magnetic center of the stator in the axial direction is displaced from the magnetic center of the rotor magnet in the axial direction, a similar unstable characteristic shape appears in the axial component of the driving force. These unstable torques and unstable axial driving forces are the main sources of structural vibration and radial noise. The fundamental frequency f of the switching noise in the three-phase motor is expressed by the following equation.

F = (3 × P) × Ω / 60 = P × Ω / 20 (1) where Ω: number of rotations of motor (rpm) P: number of poles of magnet f: switching frequency (Hz) switching noise One means of reducing torque ripple is to reduce torque ripple. FIG. 9 shows the switching torque characteristics of the three-phase motor, and the angle α in FIG.
Is given by the following equation.

Α = 360 / (3 × P) = 120 / P (2) where P: number of poles of the magnet α: switching angle (°) A normal three-phase motor has one annular rotor magnet and , And one control circuit for switching the current when switching from one phase to another phase. As a result, the driving torque or driving force has a time characteristic indicated by a solid line A or a solid line B in FIG.
The torque fluctuation around the axis becomes large.

In order to reduce the torque fluctuation in this conventional one-stator / one-rotor type motor, to improve the torque characteristics of the motor, or to realize various characteristics with one motor, two stators are provided in the axial direction. Has been proposed. In this type of motor, the mounting angle of the two stators has a phase difference of substantially α / 2 with respect to the angle α in FIG. As a result, the torque generated in each stator becomes the time characteristic shown by the solid line A and the time characteristic shown by the solid line B in FIG. When this is compared with the output torque characteristic of a conventional one-stator / one-rotor motor, the torque fluctuation is about 40%. That is, it can be seen that the torque fluctuation of the two-stator motor is significantly improved as compared with the conventional motor.

[0007] One of the prior arts corresponding to this is:
There is one disclosed in Japanese Utility Model Laid-Open No. 61-92155. In this known motor, a stator having (2n + 1) projections is divided into two core blocks in the axial direction, and these core blocks are mutually circumferentially angled 360 / (2 ×).
(2n + 1)) It is staggered, so that a more uniform torque is generated. However, since this motor has two core blocks in the axial direction,
The axial thickness of the motor increases. Further, the offset angle of the two core blocks is 360 / (2 × (2n +
1)), and sufficient attenuation of the cogging torque cannot be expected. Another prior art similar to this prior art is disclosed in Japanese Utility Model Laid-Open No. 63-153744.

Japanese Patent Application Laid-Open No. 60-241760 also discloses a motor having two stators in the axial direction. In this motor, the stator and the rotor magnet face each other in the radial direction. An object of the prior art is to provide a motor having characteristics corresponding to various demands, and this is realized by supplying a different current or the like to each stator. However, Japanese Unexamined Patent Publication No.
Japanese Patent No. 241760 does not disclose the circumferential offset angle of the two stator cores, and does not disclose a specific configuration for improving torque characteristics.

Further, Japanese Utility Model Application Laid-Open No. Sho 60-177773 discloses a motor structure which has two stators and two rotor magnets which are opposed in the axial direction and vertically above and below the axial direction. In this prior art, the supply of the drive current to the coils of the stator is the same, and the two rotor magnets are arranged with an electrical angle of 90 degrees from each other, thereby smoothing the drive torque. Also, Japanese Patent Application Laid-Open
Japanese Patent Application Publication No. 314640 discloses a motor structure which does not have a central shaft but has a stator and a rotor magnet arranged opposite to each other vertically in the axial direction. This motor has two stators and one
This is a rotor magnet type motor, and is characterized by a thin structure.

Japanese Unexamined Patent Publication No. 7-308055 discloses a motor in which one stator is arranged between two rotor magnets arranged inward and outward in the circumferential direction. In this motor, the rotor magnets are differently magnetized in accordance with the magnetic field of the stator core.
This known motor is a one-stator / two-rotor magnet type motor, and it is an object of this motor structure to increase the magnetic flux directivity of the rotor magnet and improve the output efficiency of the circumferential motor. However, there is no mention of smoothing the torque characteristics in the rotational direction and improving the characteristics.

[0011] All of the prior art stators have a structure having two stators or magnets in the axial direction, and it is difficult to realize a thin motor. The installation phase difference (offset angle in the circumferential direction) of the two stators substantially corresponds to α / 2 with respect to the angle α shown in FIG. 9, but both of the two stators are arranged in the axial direction. Therefore, a thin motor cannot be configured. Further, since the installation position phase difference between the two stators is made substantially equal to α / 2, the combined torque fluctuation with less pulsation in consideration of the magnetic pole edge effect and the like is not realized.

[0012]

In recent years, there has been an increasing demand for smaller, thinner, and faster disk drives, and the spread of personal computers equipped with disk drives in offices has made it possible to reduce noise as much as possible. It has been demanded. Therefore, an object of the present invention is to provide a spindle motor that is thin and has low noise despite high speed rotation. Another object of the present invention is to provide a spindle motor having high rotation efficiency by minimizing fluctuations in the torque characteristics around the axis of the motor.

Still another object of the present invention is to provide a disk drive device which is thin and has a quiet operation sound despite its high access speed.

[0014]

SUMMARY OF THE INVENTION The present invention provides a rotor hub rotatably held via a bearing, an annular inner rotor magnet fixed to an inner peripheral mounting portion of the rotor hub, and an inner peripheral magnet. An annular outer rotor magnet fixed to an outer peripheral mounting portion of the rotor hub located radially outward from the mounting portion, a bracket forming a stationary portion, and a small space in the radial direction with respect to the inner rotor magnet. The inner stator fixed to the inner peripheral side mounting portion of the bracket is opposed to the outer rotor magnet at a small interval in the radial direction, and is radially outward from the inner peripheral side mounting portion of the bracket. An outer stator fixed to an outer peripheral side mounting portion of the bracket, wherein the inner stator and the outer stator are arranged in a rotating direction of the rotor hub. A spindle motor fixed to the bracket with an offset angle of α / 2 (here, α = 120 ° / P, where P is the number of poles of a rotor magnet) in mechanical angles to each other. It is.

According to the present invention, the inner rotor magnet is fixed to the inner mounting portion of the rotor hub, the outer rotor magnet is fixed to the outer mounting portion, and the inner rotor magnet is fixed to the inner mounting portion of the bracket. The inner stator is fixed to face the outer stator, and the outer stator is fixed to the outer peripheral mounting portion of the bracket so as to face the outer rotor magnet. Therefore, the motor structure has two stators and two rotor magnets arranged in the radial direction.
It is a two-rotor magnet type. With such a structure, a large driving torque can be obtained while reducing the thickness of the motor. Further, since the inner stator and the outer stator are fixed with an offset angle of α / 2 in the rotation direction of the rotor hub, torque fluctuation is reduced as compared with the conventional art, and generation of noise due to torque fluctuation is suppressed. And the rotor hub can stably rotate at a high speed. The inner rotor magnet and the outer rotor magnet are fixed without being substantially offset in the rotation direction of the rotor hub.

Further, in the present invention, the offset angle β1 ° (mechanical angle) between the inner stator and the outer stator.
Is characterized in that β1 = α / 2 ± δ, where | δ | ≦ 1 ゜ (mechanical angle). According to the present invention, the offset angle β1 between the inner stator and the outer stator is (α / 2 ±
δ) degree, the trick ripple at the time of switching of the drive current is reduced, and thereby the torque fluctuation can be effectively suppressed.

Further, the present invention provides a rotor hub rotatably held via a bearing, an annular inner rotor magnet fixed to an inner peripheral mounting portion of the rotor hub, and a radius larger than the inner peripheral mounting portion. An annular outer rotor magnet fixed to the outer peripheral side mounting portion of the rotor hub located on the outer side in the direction, a bracket constituting a stationary portion, and opposed to the inner rotor magnet via a minute interval in the radial direction,
The inner stator fixed to the inner mounting portion of the bracket and the outer rotor magnet are opposed to the outer rotor magnet at a small interval in the radial direction, and are located radially outward from the inner mounting portion of the bracket. An outer stator fixed to the outer peripheral side of the bracket, wherein the inner rotor magnet and the outer rotor magnet have a mechanical angle α / 2 relative to each other with respect to the rotation direction of the rotor hub.
(Here, α = 120 ° / P, P is the number of poles of the rotor magnet) The spindle motor is fixed to the rotor hub with an offset angle.

According to the present invention, as described above, the motor structure is a two-stator / two-rotor magnet type in which two stators and two rotor magnets are arranged in the radial direction. Thus, a large driving torque is obtained while reducing the thickness of the motor. In addition, since the inner rotor magnet and the outer rotor magnet are fixed with an offset angle of α / 2 in the rotation direction of the rotor hub, torque fluctuation is reduced as compared with the conventional art, and noise caused by torque fluctuation is reduced. In addition, the rotor hub can be stably rotated at a high speed. The inner stator and the outer stator are fixed without being substantially offset in the rotation direction of the rotor hub.

In the present invention, the offset angle β between the inner rotor magnet and the outer rotor magnet is
1 ° (mechanical angle) is characterized in that β1 = α / 2 ± δ, where | δ | ≦ 1 ゜ (mechanical angle). According to the present invention, since the offset angle β1 of the fixed position between the inner rotor magnet and the outer rotor magnet is (α / 2 ± δ) degrees, the trick ripple at the time of switching of the drive current is reduced, thereby reducing the torque fluctuation. It can be suppressed effectively.

Also, in the present invention, the inner stator and the outer stator are integrally formed to form a common stator annular portion, and a plurality of the inner stators are provided on an inner peripheral portion of the stator annular portion. A tooth portion is provided integrally, and a plurality of tooth portions of the outer stator are provided integrally on an outer peripheral portion thereof. According to the present invention, the plurality of teeth of the inner stator are integrally provided on the inner periphery of the common stator annular portion, and the plurality of teeth of the outer stator are integrally formed on the outer periphery of the stator annular portion. Therefore, the inner stator and the outer stator can be formed into an integral structure with a relatively simple configuration.

In the present invention, the rotor hub is provided with an annular connecting member, the inner rotor magnet is fixed to an inner peripheral surface of the connecting member, and the outer rotor magnet is fixed to an outer peripheral surface of the connecting member. The inner rotor magnet and the outer rotor magnet are integrally formed via the annular connecting member. According to the present invention, the inner rotor magnet is fixed to the inner peripheral surface of the connecting member provided on the rotor hub,
Since the outer rotor magnet is fixed to the outer peripheral surface of the connecting member, the inner rotor magnet and the outer rotor magnet can be integrally formed with a relatively simple configuration.

Further, the present invention relates to a disk drive device on which a disk-shaped recording disk capable of recording information is mounted,
9. A spindle motor according to claim 1, further comprising: a housing; a spindle motor disposed inside the housing for rotating the recording disk; and a head means for writing and / or reading information on the recording disk. When,
A disk moving device for moving the head means in a radial direction of the recording disk.

According to the present invention, since the spindle motor according to any one of the first to sixth aspects is provided, the thickness of the disk drive device can be reduced, and noise caused by torque fluctuation of the spindle motor can be reduced. Generation can be suppressed, and operation noise of the disk drive device can be reduced.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a spindle motor according to the present invention and a disk drive device provided with the same will be described below with reference to FIGS. FIG. 1 is a sectional view schematically showing an embodiment of a disk drive according to the present invention, and FIG. 2 is a sectional view showing a spindle motor (a spindle motor according to the present invention) of the disk drive of FIG. FIG. 3 is a plan view schematically showing a magnetic circuit configuration in the spindle motor of FIG.
FIG. 5 is a plan view schematically showing a magnetic circuit configuration of a modification, FIG. 5 is a cross-sectional view schematically showing another embodiment of the spindle motor, and FIG. It is a top view which shows a circuit structure simply.

In FIG. 1, the illustrated disk drive includes an apparatus housing 4 that defines a storage chamber 2. The apparatus housing 4 seals a base member 6 having an open upper surface and an upper surface opening of the base member 6. It is composed of a cover 8. In the accommodation room 2, a recording disk 10 such as a hard disk, a spindle motor 12, a head means 14 such as a magnetic head, and a head moving mechanism 16 are provided. As will be described later, the spindle motor 12
A bracket 18 constituting a stationary portion, and the bracket 1
A bracket 18 is attached to the base member 6 of the apparatus housing 4, and a plurality of recording disks 10 are attached to the rotor hub 20.
Is installed. Therefore, when the rotor hub 20 is driven to rotate, the plurality of recording disks 10 are rotated in a predetermined direction integrally therewith. Incidentally, the bracket 18 may be formed integrally with the base member 6 of the device housing 4.

The head means 14 is provided corresponding to the recording surface of each recording disk 10. Head moving mechanism 16
Is provided with, for example, an arm member 22 provided to be swingable in correspondence with each head means 14 and a voice coil motor (not shown) for swinging the arm member 22. The head means 14 is attached to the tip of the. Accordingly, when the voice coil motor operates, the arm member 22 swings, the head means 14 mounted on the tip of the arm member 22 moves in the radial direction of the recording disk 10, and the head means 14 puts information on the recording surface of the recording disk 10. And / or read the written information.

Next, the illustrated spindle motor 12 will be described mainly with reference to FIG. Bracket 18
Has a bracket body 24, and the bracket body 24
Is provided on the inner peripheral side of the bracket 18, an annular inner support wall 26 constituting an inner peripheral side mounting portion of the bracket 18 is provided, and on the outer peripheral side of the bracket body 24 located radially from the inner peripheral side mounting portion, Is provided with an annular outer supporting wall 28 which constitutes the outer peripheral side mounting portion. A boss 30 is provided at the center of the bracket body 24,
One end (lower end) of the shaft member 32 is fixed to the boss 30 by, for example, press-fitting, and the other end of the shaft member 32 extends substantially vertically upward from the bracket body 24. The inner support wall 26 and the outer support wall 2 of the bracket body 24
The magnetic circuit arrangement 34 is disposed in the annular space between the magnetic circuit arrangements 8 and 8. The magnetic circuit configuration 34 will be described later.

The rotor hub 20 has a substantially cylindrical hub body 36.
The hub body 36 is rotatably supported by the shaft member 32 via a pair of bearings 38 and 40. At the lower end of the hub body 36, there is provided a disk mounting portion 42 protruding outward in the radial direction, and a plurality of recording disks 10 are mounted on the disk mounting portion 42 via an annular spacer 44. It is attached to the hub body 36 by a clamp member 46 attached to the upper end surface of the hub 36.

Referring to FIG. 3 together with FIG. 2, the magnetic circuit configuration 34 will be described.
The magnetic circuit configuration 34 is comprised of two stators, an inner stator 48 and an outer stator 50, and two rotor magnets, an inner rotor magnet 52 and an outer rotor magnet 54. Inner stator 48
Is mounted on the outer peripheral surface of the inner support wall 26 of the bracket body 24, and the outer stator 50 is mounted on the inner peripheral surface of the outer support wall 28 of the bracket body 24. The inner stator 48 includes an inner stator core 56 and a three-phase coil 60 wound around the inner stator core 56. The inner stator core 56 has an annular portion 58,
The annular portion 58 is attached to the inner support wall 26, and a plurality of (in this case, nine) teeth portions 62 are arranged at substantially equal intervals in the circumferential direction. Extend radially outward from the annular portion 58 in the radial direction, and the three-phase coils 60
2 is wound as required in a known manner. Also,
The outer stator 50 includes an outer stator core 64 and a three-phase coil 66 wound around the outer stator core 64. The outer stator core 64 has an annular portion 68
The annular portion 68 is attached to the outer support wall 28, and a plurality of (in this case, nine) tooth portions 7
0 are disposed at substantially equal intervals in the circumferential direction, the plurality of teeth portions 70 extend radially inward from the annular portion 68 in the radial direction, and the three-phase coils 66 The teeth 70 are wound as required in the same manner as the three-phase coils 60.

In this spindle motor 12, an annular connecting member 72 is attached to the lower end surface of the disk mounting portion 42 of the hub main body 36.
As shown in FIG. 3, a space between the inner stator 48 and the outer stator 50, specifically, a plurality of inner circles and a plurality of outer stators 50 defined by tips of a plurality of teeth 62 of the inner stator 48. The space between the outer circle defined by the tips of the teeth portions 70 extends toward the bracket body 24. Inner rotor magnet 52
Is formed of an annular magnet, and is attached to the inner peripheral surface of a connecting member 72 that constitutes an inner attachment portion of the rotor hub 20. The inner rotor magnet 52 is magnetized in the radial direction and is magnetized to eight poles in the circumferential direction.
The magnetic poles in the radially inner peripheral portion are alternately N poles and S poles as shown by "N" and "S" in FIG. The inner peripheral surface of the inner rotor magnet 52 is opposed to the distal end surfaces of the plurality of teeth portions 62 of the inner stator 48 located radially inward with a small interval. The outer rotor magnet 54 is formed of an annular magnet, and is attached to the outer peripheral surface of a connecting member 72 that constitutes an outer attachment portion of the rotor hub 20. The outer rotor magnet 54 is also magnetized in the radial direction and is magnetized to eight poles in the circumferential direction. Have an N pole and an S pole. The outer peripheral surface of the outer rotor magnet 54 is opposed to the distal end surfaces of the plurality of teeth portions 70 of the outer stator 50 located radially outward with a small interval.

In the magnetic circuit configuration 34, as shown in FIG. 3, the inner stator 48 and the outer stator 50 are offset by a predetermined angle in the rotation direction of the rotor hub 20 indicated by the arrow 74. The offset angle β1 (mechanical angle), that is, between the central axis 76 of the specific tooth portion 48a of the inner stator 48 and the central axis 78 of the specific tooth portion 50a of the outer stator 50 corresponding to the specific tooth portion 48a of the inner stator 48. Is β1 = α / 2 ± δ, where α = 120 ° / P, P is the number of poles of the inner and outer rotor magnets 52, 54, and | δ | ≦ 1 ° (mechanical angle). . On the other hand, the inner rotor magnet 52 and the outer rotor magnet 54 are not substantially offset in the rotation direction of the rotor hub 20 as shown in FIG. ) Is disposed radially outward of the outer rotor magnet 54, for example, an N-pole (magnetic pole at the outer peripheral portion) thereof. For example, an S pole (a magnetic pole on the outer peripheral portion) of the outer rotor magnet 54 is arranged. By setting the inner stator 48 and the outer stator 50 to such an offset angle, as described later, the three-phase coil 60 of the inner stator 48 and the outer stator 5
The torque ripple at the time of switching of the driving current supplied to the three-phase coil 66 of 0 is reduced, and the fluctuation of the driving torque generated by this can be suppressed.

In this spindle motor, the three-phase coil 60 of the inner stator 48 and the outer stator 52
The driving current is supplied to the three-phase coil 66 as required, and the switching of the driving current to both coils 60 and 66 is performed simultaneously. Therefore, the driving torque acts on the rotor hub 20 by the mutual magnetic action between the inner stator core 56 of the inner stator 48 and the inner rotor magnet 52 magnetized by the driving current, and the outer stator core 6 of the outer stator 50 magnetized by the driving current.
A drive torque acts on the rotor hub 20 by a mutual magnetic action between the outer rotor magnet 4 and the outer rotor magnet 54, and the rotor hub 20 (the recording disk 10 mounted thereon and integrally therewith) is rotationally driven in a predetermined direction by the drive torque. Thus, the rotor hub 20 is rotationally driven with a large driving torque. Three-phase coil 6 of inner stator 48
The drive currents to the three-phase coils 66 of the zero and outer stators 52 are sequentially and simultaneously switched and supplied. However, the inner stator 48 and the outer stator 50 are mutually at a predetermined angle in the rotation direction of the rotor hub 20, preferably (α / 2 ± δ)
Because of the degree (°) deviation, the torque ripple generated at the time of switching of the drive current becomes small, and thereby, the fluctuation of the drive torque can be suppressed and the noise at the time of rotation can be reduced. In addition, the magnetic circuit configuration 34 has a configuration in which the inner and outer stators 48 and 50 and the inner and outer rotor magnets 52 and 54 are arranged in the radial direction. Can be achieved.

Next, a modification of the magnetic circuit configuration of the spindle motor will be described with reference to FIG. In this modification, the arrangement of the two stators and the two rotor magnets is modified, and can be used instead of the magnetic circuit configuration 34 in the spindle motor shown in FIGS. 4, in the magnetic circuit configuration 34A, the inner stator 48A attached to the inner support wall 26 (see FIG. 2) of the bracket main body 24 includes an inner stator core 56A and a three-phase coil 60A wound around the inner stator core 56A. The outer stator 50A that is configured and attached to the outer support wall 28 (see FIG. 2) of the bracket body 24 includes an outer stator core 64A and a three-phase coil 66A wound around the outer stator core 64A.
It is composed of Also, the inner rotor magnet 52
A and the outer rotor magnet 54A are disposed in a space between the inner stator 48A and the outer stator 50A,
The inner rotor magnet 48A faces the plurality of teeth portions 62A of the inner stator 48A, and
The outer rotor magnet 50A is attached to the outer peripheral surface of the connecting member 72 in opposition to the plurality of teeth portions 70A of the outer stator 50A (see FIG. 2). The basic configurations of these stators 48A, 50A and rotor magnets 52A, 54A are shown in FIGS.
Are substantially identical to the inner and outer stators 48, 50 and the inner and outer rotor magnets 52, 54 shown in FIG.

In this modification, as shown in FIG. 4, the inner rotor magnet 52A and the outer rotor magnet 54
A is offset by a predetermined angle in the rotation direction of the rotor hub 20 (see FIG. 2) indicated by the arrow 74. This offset angle β2 (mechanical angle), that is, the inner rotor magnet 52
A of the center axis 82 in the circumferential direction of the specific magnetic pole portion 52Aa and the inner rotor magnet 52 of the outer rotor magnet 54A.
A specific magnetic pole part 54Aa corresponding to the specific magnetic pole part 52Aa of A
Is the angle between the circumferential center axis 84 and β2 = α / 2 ± δ, where α = 120 ° / P, where P is the number of poles of the inner and outer rotor magnets 52A and 54A, | δ | ≦ 1 ° (mechanical angle), is set to. On the other hand, the inner stator 48A and the outer stator 50A are not substantially offset in the rotation direction of the rotor hub 20 (see FIG. 2) as shown in FIG. , Each tooth portion 70A of the outer stator 50A is disposed. By setting the inner rotor magnet 52A and the outer rotor magnet 54A at such an offset angle, the magnetic relationship between the inner stator 48A and the inner rotor magnet 52A and the magnetic relationship between the outer stator 50A and the outer rotor magnet 54A can be improved. However, FIGS.
These magnetic relationships are substantially the same as those in the embodiment described above. Therefore, as described above, the torque ripple at the time of switching of the drive current is reduced, and the fluctuation of the generated drive torque can be suppressed.

Next, another embodiment of the spindle motor will be described with reference to FIGS. In this other embodiment, the arrangement of the two stators and the two rotor magnets is modified, and the other configuration is substantially the same as the embodiment shown in FIGS. 5 and 6, a spindle motor 102 includes a bracket 104 (constituting a stationary portion) attached to a base member (not shown) of a disk drive, and a rotor hub 106 rotatable with respect to the bracket 104.
A plurality of recording disks 108 are provided on the rotor hub 106 in the same manner as described above, for example.
Attached via 0. The bracket 104 has a bracket body 112, and a shaft member 114 is fixed to the bracket body 112. The rotor hub 106 has a hub body 116, and the hub body 116
It is rotatably supported by the shaft member 114 via the members 18 and 120.

The magnetic circuit configuration 122 of the spindle motor 102 is as follows. Bracket body 1
An annular stator support wall 124 is integrally provided on the inner support 12, and an inner stator 126 and an outer stator 128 are mounted on the stator support wall 124. And the outer stator 128 functions as an outer peripheral mounting portion to which the outer stator 128 is fixed.

The stator 130 in the magnetic circuit configuration 122 has an annular stator annular portion 132, and the stator annular portion 132 is attached to the stator support wall 124 of the bracket body 112. Stator ring 13
A plurality of (in this embodiment, nine) inner teeth portions 134 are provided at substantially equal intervals in the circumferential direction on the inner peripheral portion of the inner peripheral portion 2. And three-phase coils 136 (see FIG. 5) are wound around these inner teeth portions 134 as required. In addition, a plurality of (in this embodiment, nine) outer teeth portions 138 are provided on the outer peripheral portion of the stator annular portion 132 at substantially equal intervals in the circumferential direction, and the plurality of outer tooth portions 138 are provided. The three-phase coils 140 (see FIG. 5) extend radially outward from the stator annular portion 132 and are wound around these outer teeth portions 138 as required. With this configuration, the stator annular portion 1
32, a plurality of inner teeth portions 134 and a three-phase coil 136 wound therearound constitute an inner stator 126, and a stator annular portion 132, a plurality of outer tooth portions 138 and a three-phase coil wound therearound. The coil 140 forms the outer stator 128 and the stator annular portion 132 forms part of the inner and outer stators 126,128.

In the magnetic circuit structure 122, an annular inner rotor magnet 142 is disposed radially inward of the plurality of inner teeth portions 134 so as to face their tip surfaces. An annular hanging portion 144 (constituting an inner circumferential side attachment portion of the rotor hub 106) extending toward the bracket body 112 is provided on an inner circumferential portion of the hub body 116, and an inner rotor magnet 142 is provided on an outer circumferential surface of the annular hanging portion 144.
Is attached. Further, an annular outer rotor magnet 146 is disposed radially outward of the plurality of outer teeth portions 138 so as to face the tip surfaces thereof. An annular yoke member 150 (constituting an outer peripheral side attachment portion of the rotor hub 106) is attached to a lower end surface of the disk mounting portion 148 of the hub body 116.
An outer rotor magnet 146 is attached to the inner peripheral surface of the outer rotor. Inner and outer rotor magnets 142, 14
6 has substantially the same configuration as the embodiment shown in FIGS.

In the magnetic circuit structure 122, as shown in FIG. 6, the inner stator 126 and the outer stator 128 are offset by a predetermined angle in the rotation direction of the rotor hub 106 indicated by the arrow 154. This offset angle β1
(Mechanical angle), that is, the center axis 156 of the specific inner teeth portion 134a of the inner stator 126 and the outer stator 128
Of the specific inner teeth portion 134a of the inner stator 126
Center axis 15 of the specific outer teeth portion 138a corresponding to
8 is β1 = α / 2 ± δ, where α = 120 ° / P, P is the number of poles of the inner and outer rotor magnets 142 and 146, | δ | ≦ 1 ° (mechanical angle), Is set to On the other hand, as shown in FIG. 6, the inner rotor magnet 142 and the outer rotor magnet 146 are not substantially offset in the rotation direction of the rotor hub 106, and are, for example, N poles (“N” in FIG. 6) of the inner rotor magnet 142. Indicates the magnetic poles on the outer periphery)).
For example, the N pole of the outer rotor magnet 146 (“N” in FIG. 6 indicates a magnetic pole at the inner periphery thereof) is disposed.
For example, on the radially outer side of the S pole (“S” in FIG. 6 indicates the magnetic pole on the outer periphery) of the inner rotor magnet 142,
For example, an S pole (“S” in FIG. 6 indicates a magnetic pole on the outer periphery) of the outer rotor magnet 146 is arranged.

In the spindle motor having such a magnetic circuit configuration 122, the inner stator 126 (the plurality of inner teeth portions 134) and the outer stator 128 (the plurality of outer tooth portions 138) are rotated in the rotation direction of the rotor hub 106. , The three-phase coils 13 of the inner stator 126 are provided in the same manner as described above.
The torque ripple at the time of switching of the driving current supplied to the three-phase coils 140 of the outer stator 6 and the outer stator 128 is reduced, and the fluctuation of the driving torque generated thereby can be suppressed.

In the embodiment shown in FIGS. 5 and 6, in the magnetic circuit configuration 122 in which the inner and outer stators 126 and 128 are arranged between the inner and outer rotor magnets 142 and 146, the inner stator 126 and the outer stator 128 are arranged. Are offset from each other by a predetermined angle, but instead of such a configuration, in the magnetic circuit configuration of the above-described embodiment, similarly to the modification shown in FIG. The magnet 146 and the magnet 146 may be configured so as to be offset from each other by a predetermined angle, and the same effect is achieved by such a configuration.

In the embodiment described above, the magnetic circuit configuration is 8
Although the description has been made by applying the present invention to a spindle motor having 9 poles and 9 slots, the present invention is not limited to such a magnetic circuit configuration, and may be similarly applied to a spindle motor having a magnetic circuit configuration of 8 poles and 12 slots. it can. Example and Comparative Example The rotational torque was determined using the magnetic circuit configuration shown in FIG. The magnetic circuit configuration includes two stators and two rotor magnets, and two magnetic members are provided between the inner stator and the outer stator.
In this configuration, two rotor magnets are arranged. The inner and outer stators each have nine teeth arranged at equal intervals in the circumferential direction, and each of the three-phase coils in the inner and outer stators is connected to three continuous teeth. The windings are alternately wound clockwise, counterclockwise, and clockwise, and the offset angle in the rotation direction between the inner stator and the outer stator is β1 = [(120
° / 8/2) + 0.5 °] = 8.0 ° (α = 120 °,
P = 8, δ = 0.5 °). On the other hand, the inner and outer rotor magnets were alternately provided with N poles and S poles at equal intervals in the circumferential direction, and the number of these magnetic poles was eight in total.

The operation result of this magnetic circuit configuration was as shown in FIG. In FIG. 7, the solid line A indicates the cogging torque of the magnetic circuit configuration, and the dashed line B indicates the rotational torque generated by the mutual magnetic action between the inner stator and the inner rotor magnet in the magnetic circuit configuration. C is a rotational torque generated by a mutual magnetic action between the outer stator and the outer rotor magnet.
A broken line D is a combined rotational torque generated by the inner and outer stators and the inner and outer rotor magnets, and a solid line E is a total rotational torque (the combined rotational torque and the cogging) acting on the rotor hub by the magnetic circuit configuration. Rotation torque). At this time,
The fluctuation rate of the combined rotation torque was 6.53%, and the fluctuation rate of the total rotation torque was 13.07%.

As a comparative example, a rotational torque was determined using a magnetic circuit configuration in the form of an inner rotor. The outer stator has nine teeth arranged at equal intervals in the circumferential direction, and each coil of the three-phase coil is alternately clockwise and counterclockwise in three consecutive teeth. And a configuration wound clockwise. On the other hand, the inner rotor magnet has N poles and S poles alternately arranged at equal intervals in the circumferential direction, and the total number of these magnetic poles is eight.

The operation result of this magnetic circuit configuration was as shown in FIG. 8, the solid line F indicates the cogging torque of the magnetic circuit configuration, the broken line G indicates the rotational torque generated by the stator and the rotor magnet in the magnetic circuit configuration, and the solid line H indicates the rotor hub of the magnetic circuit configuration. (The rotation torque obtained by adding the rotation torque and the cogging torque). At this time, the fluctuation rate of the combined rotation torque is 16.04.
%, And the fluctuation rate of the total rotation torque was 26.24%.

From the above operation results, it can be seen that the cogging torque is smaller in the embodiment and the fluctuation of the total rotation torque is smaller than in the comparative example, so that the rotor hub can be driven to rotate stably at high speed. In a 2-stator / 2-motor magnet opposed in the radial direction at the same axial height, even when the mutual stators and the mutual magnets are mounted without a phase difference, the current supplied to each stator is controlled by an inverter or the like. By electrically controlling the phase difference of α / 2 or α / 2 ± δ by using the means, it is possible to realize a motor having the same effect.

[0047]

According to the spindle motor of the first aspect of the present invention, the motor structure is a two-stator / two-rotor magnet type in which two stators and two rotor magnets are arranged in the radial direction. A large driving torque can be obtained while reducing the thickness of the device. In addition, since the inner stator and the outer stator are offset by a predetermined angle in the rotation direction of the rotor hub, torque fluctuations are reduced as compared with the conventional art, so that noise caused by torque fluctuations can be suppressed and the rotor hub can be stabilized. Can rotate at high speed.

According to the spindle motor of the second aspect of the present invention, a trick ripple at the time of switching of the drive current is reduced, thereby effectively suppressing the torque fluctuation. According to the spindle motor of the third aspect of the present invention, it is possible to obtain a large driving torque while reducing the thickness of the motor, reduce the torque fluctuation compared to the conventional motor, and reduce the noise caused by the torque fluctuation. Can be suppressed.

Further, according to the spindle motor of the fourth aspect of the present invention, the trick ripple at the time of switching of the drive current is reduced, whereby the torque fluctuation can be effectively suppressed. Further, according to the spindle motor of the fifth aspect of the present invention, the inner stator and the outer stator can be integrally formed with a relatively simple configuration. According to the spindle motor of the sixth aspect of the present invention, the inner rotor magnet and the outer rotor magnet can be integrally formed with a relatively simple configuration.

Further, according to the disk drive of claim 7 of the present invention, the overall thickness of the device can be reduced.
Further, it is possible to suppress the generation of noise due to the torque fluctuation of the spindle motor, and to reduce the operation noise of the disk drive.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing an embodiment of a disk drive device according to the present invention.

FIG. 2 is a sectional view showing a spindle motor (a spindle motor according to the present invention) of the disk drive device of FIG. 1;

FIG. 3 is a plan view schematically showing a magnetic circuit configuration in the spindle motor of FIG. 2;

FIG. 4 is a plan view schematically showing a magnetic circuit configuration according to a modified embodiment.

FIG. 5 is a sectional view schematically showing another embodiment of a spindle motor.

FIG. 6 is a plan view schematically showing a magnetic circuit configuration in the spindle motor of FIG. 5;

FIG. 7 is a diagram illustrating an operation result of the magnetic circuit configuration of the example.

FIG. 8 is a diagram showing an operation result of a magnetic circuit configuration of a comparative example.

FIG. 9 is a diagram showing torque acting on a rotor hub of a conventional three-phase motor.

[Brief description of reference numerals]

 Reference Signs List 4 apparatus housing 10 recording disk 12, 102 spindle motor 14 head means 16 head moving mechanism 18, 112 bracket 20, 106 rotor hub 26 inner support wall 28 outer support wall 34, 34A, 122 magnetic circuit configuration 36, 116 hub body 48, 48A , 126 Inner stator 50, 50A, 128 Outer stator 52, 52A, 142 Inner rotor magnet 54, 54A, 146 Outer rotor magnet 72 Connecting member 130 Stator

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02K 1/27 502 H02K 1/27 502A 21/12 21/12 MF term (Reference) 5D109 BA01 BA02 BA13 BA18 BA20 BA26 BA28 5H002 AA01 AA09 AB04 AB05 AC06 5H621 AA02 AA04 BB01 BB07 GA01 GA04 GA15 GA16 GB08 JK13 JK17 5H622 AA02 AA03 CA02 CA05 CA10 CA14 CB03 PP01

Claims (7)

[Claims] 1. A rotor hub rotatably held via a bearing, an annular inner rotor magnet fixed to an inner peripheral mounting portion of the rotor hub, and a radially outer position from the inner peripheral mounting portion. An annular outer rotor magnet fixed to the outer peripheral mounting portion of the rotor hub, a bracket constituting a stationary portion, and the inner rotor magnet opposed to the inner rotor magnet at a small interval in a radial direction, and an inner periphery of the bracket. An inner stator fixed to a side mounting portion, and an outer peripheral mounting portion of the bracket which is opposed to the outer rotor magnet via a minute interval in a radial direction and is located radially outward from the inner peripheral mounting portion of the bracket. And an outer stator fixed to the portion, wherein the inner stator and the outer stator have a mechanical angle α / with respect to a rotation direction of the rotor hub. 2 (where α = 120 ° / P, P is the number of poles of the rotor magnet)
A spindle motor fixed to the bracket with an offset angle only. 2. An offset angle β1 ° (mechanical angle) between the inner stator and the outer stator is β1 = α / 2 ± δ, where | δ | ≦ 1 ゜ (mechanical angle). The spindle motor according to claim 1, wherein 3. A rotor hub rotatably held via a bearing, an annular inner rotor magnet fixed to an inner peripheral side mounting portion of the rotor hub, and a radially outer side of the inner peripheral side mounting portion. An annular outer rotor magnet fixed to the outer peripheral mounting portion of the rotor hub, a bracket constituting a stationary portion, and the inner rotor magnet opposed to the inner rotor magnet at a small interval in a radial direction, and an inner periphery of the bracket. An inner stator fixed to a side mounting portion, and an outer peripheral mounting portion of the bracket which is opposed to the outer rotor magnet via a minute interval in a radial direction and is located radially outward from the inner peripheral mounting portion of the bracket. An outer stator fixed to the rotor hub, wherein the inner rotor magnet and the outer rotor magnet are Spindle motor, wherein the alpha / 2 (where, α = 120 ° / P, P is the number of poles of the rotor magnet) in mechanical angle is fixed to the rotor hub with a offset angle. 4. An offset angle β1 ° between the inner rotor magnet and the outer rotor magnet (mechanical angle).
4. The spindle motor according to claim 3, wherein: β1 = α / 2 ± δ, where | δ | ≦ 1 ゜ (mechanical angle). 5. The inner stator and the outer stator are integrally formed to form a common stator annular portion, and a plurality of teeth portions of the inner stator are integrated with an inner peripheral portion of the stator annular portion. The spindle motor according to any one of claims 1 to 4, wherein a plurality of teeth portions of the outer stator are integrally provided on an outer peripheral portion of the spindle motor. 6. An annular connecting member is provided on the rotor hub, the inner rotor magnet is fixed to an inner peripheral surface of the connecting member, and the outer rotor magnet is fixed to an outer peripheral surface of the connecting member. And the outer rotor magnet is integrally formed via the annular connecting member.
The spindle motor according to any one of claims 1 to 4. 7. A disk drive on which a disk-shaped recording disk capable of recording information is mounted, comprising: a housing;
9. The spindle motor according to claim 1, wherein the spindle motor is disposed inside the housing and drives the recording disk to rotate, and a head means for writing and / or reading information to and from the recording disk. A disk moving device for moving a head means in a radial direction of the recording disk.