JP2003264954A - Motor and disc device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spindle motor which is possible of downsizing while having slip stop construction. <P>SOLUTION: In the spindle motor 52 to be used for a disc drive or the like, a rotor magnet 14 is fixed to a rotor 6 of the body of rotation via a yoke 18. A base member 2 constituting a thrust bearing part is fixed to a bracket 10, and it constitutes a fixing body of the spindle motor 52 together with a stator 12. The yoke 18 is provided with an annular projection 18a which projects toward a shaft 4, and the base member 2 is provided with an annular flange 2a1 which projects in the reverse direction from the shaft 4 via a cylindrical wall 2a. Consequently, when the rotor shifts in the direction of parting from the rotor, the flange 2a1 and the projection 18a abut on each other, which regulates quantity of shifting in axial direction of the rotor. Moreover, since slip stop structure is provided except for the bearing part, the downsizing of the spindle motor 52 can be materialized. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor and a disk device using the motor.

[0002]

2. Description of the Related Art Conventionally, as a bearing of a motor for driving a recording disk in a disk drive device such as a hard disk device or a removable disk device, a fluid dynamic pressure such as oil interposed between a shaft which is a rotating shaft and a sleeve. A dynamic pressure bearing that utilizes is adopted. In a motor using such a dynamic pressure bearing, the rotating body is moved in the direction opposite to the direction away from the fixed body (that is,
Regardless of the posture of the motor, in the thrust bearing that supports the thrust load supporting pressure of the motor, prevent the rotor from becoming unstable due to the rotor being constantly pressed against the fixed body). A magnetic attractive force acts between the body and the fixed body. For example, measures have been taken such as arranging the field magnet and the armature so as to be displaced in the axial direction.

On the other hand, in recent years, since a disk drive device using a motor having a dynamic pressure bearing has been downsized and mounted in various portable electronic devices, it is necessary to design a motor capable of withstanding a shock. ing. Therefore, a retaining structure has been proposed that prevents the shaft from coming off the sleeve. For example, there has been proposed a structure in which an annular protrusion is provided on the outer periphery of the shaft and the protrusion contacts the sleeve when the shaft moves in the direction of coming out of the sleeve.

[0004]

However, since the design is conventionally performed from the viewpoint of preventing the shaft from coming off,
A retaining structure has been provided in the bearing portion. Therefore,
It was necessary to take measures to prevent particles generated from the retaining structure from entering between the shaft and the sleeve when the motor is assembled or when a shock is applied.

Further, there is an increasing demand for further downsizing of the disk drive device, and further downsizing of the motor is also required. However, when a retaining structure is provided in the bearing portion, further downsizing becomes difficult because the bearing structure and the retaining structure are arranged in the axial direction.

The present invention has been made in view of the above problems, and its main object is to easily downsize a motor having a retaining structure.

[0007]

According to a first aspect of the present invention, there is provided an electric motor in which a field magnet arranged around a central axis is attached via a yoke. And a second member facing the field magnet and having an armature attached thereto that generates a rotational force around the central axis between the field magnet and the field magnet. A protruding portion that is supported so as to be rotatable relative to the second member about the central axis, and that the yoke protrudes in a direction perpendicular to the central axis at an end portion on the second member side. And the second member has a locking portion that comes into contact with the protruding portion when the first member moves in a direction away from the second member.

The invention according to claim 2 is the motor according to claim 1, wherein the second member has a thrust bearing member, and the engaging portion is a part of the thrust bearing member. .

According to a third aspect of the invention, there is provided the motor according to the first or second aspect, wherein at least one of the protruding portion and the locking portion has an annular shape centered on the central axis.

The invention according to claim 4 is the motor according to any one of claims 1 to 3, wherein the yoke is longer than the field magnet in the central axis direction.

According to a fifth aspect of the present invention, in the motor according to any one of the first to fourth aspects, the field magnet is arranged closer to the central axis than the armature.

According to a sixth aspect of the invention, there is provided the motor according to any one of the first to fifth aspects, wherein the yoke is attached to the first member by laser welding.

According to a seventh aspect of the present invention, there is provided a disk device in which a disc-shaped recording medium for recording information is mounted.
7. A housing for accommodating the recording medium, a motor according to claim 1, which is fixed inside the housing to rotate the recording medium, and access means for writing or reading information to or from the recording medium. Equipped with.

[0014]

1 is a schematic diagram showing the internal structure of a disk drive device 50 according to an embodiment of the present invention. The inside of the housing 51 forms a clean space in which dust and the like are extremely small, and a spindle motor 52 having a disc-shaped disk plate 53 for storing information is installed therein. In addition, inside the housing 51, a head moving mechanism 57 for reading and writing information from the disk plate 53 is arranged.
Is a head 5 that reads and writes information on the disk plate 53.
6, arm 55 supporting this head, and head 5
6 and the arm 55 are constituted by an actuator section 54 that moves the arm 55 to a desired position on the disk plate 53.

FIG. 2 is a view showing a vertical section of the spindle motor 52. In FIG. 2, this spindle motor 52
Is a substantially disk-shaped base member (thrust receiving member) 2,
A shaft 4 having one end fixed to the central portion of the base member 2, a rotor 6 having a through hole 6a into which the shaft 4 is inserted, and an axis line of the through hole 6a (a central axis of rotation of a motor). The seal cap 8 (closure member) is provided so as to close the opening on the upper end side in the direction (i.e. The shaft 4 may be formed integrally with the base member 2.

The base member 2 has a substantially bowl-like shape, and has a housing for the disk drive (housing 5 in FIG. 1).
(Shown as 1) is fixed to a bracket 10 attached to the bracket 1 by means such as press fitting or adhesion.
On the inner peripheral surface 10a of 0, a stator (armature) 12 having a plurality of teeth protruding inward in the radial direction is arranged. In the spindle motor 52, the shaft 4, the base member 2, the bracket 10 and the stator 12 form a fixed body.

The rotor 6, which is a rotating body of the spindle motor 52, is provided with a yoke 18, which will be described later, and a rotor magnet 14, which is a field magnet, facing the stator 12 with a gap from the inside in the radial direction. Fixed through. Then, the drive mechanism formed by the stator 12 and the rotor magnet 14 generates torque (rotational force) to rotate the rotating body with respect to the fixed body with the shaft 4 as the central axis. In addition, the base member 2 and the bracket 10, the bracket 10 and the housing 51, or the base member 2, the bracket 10 and the housing 51.
It is also possible to integrate and.

A notch 6b is formed in the outer peripheral portion of the lower end side (base member 2 side) of the rotor 6, and the notch 6b is formed.
The outer peripheral surface 6b1 of b is formed in an inclined surface shape so that the diameter thereof decreases as the distance from the base member 2 increases. In addition, the base member 2 has a cylindrical wall 2a whose inner peripheral surface faces the outer peripheral surface 6b1 of the cutout portion 6b in the radial direction in a non-contact state.
It is provided concentrically with.

Between the inner peripheral surface of the cylindrical wall 2a and the outer peripheral surface 6b1 of the cutout portion 6b, between the lower end surface of the rotor 6 following the outer peripheral surface 6b1 of the cutout portion 6b and the upper surface of the base member 2, and continuously to this. A series of gaps are formed between the inner peripheral surface of the through hole 6a and the outer peripheral surface of the shaft 4, and between the end surface of the shaft 4 and the lower surface of the seal cap 8 which are continuous with this. The oil is continuously retained in the gap without interruption, forming a so-called full-fill dynamic bearing.

On the inner peripheral surface of the through hole 6a of the rotor 6, a plurality of vertical grooves 20a for generating dynamic pressure are formed in the circumferential direction over substantially the entire axial dimension of the through hole 6a. A radial dynamic pressure bearing portion 20 is configured between the outer peripheral surface of the shaft 4 and the shaft 4. Instead of these vertical grooves 20a, a plurality of herringbone dynamic pressure generating grooves may be arranged in the circumferential direction.

On the lower end surface of the rotor 6, there is a pump-in spiral groove 22 which induces a pressure toward the oil radially inward (shaft 4 side) when the rotor 6 rotates.
a is formed, and the thrust bearing portion 22 is formed between the upper surface of the base member 2. In FIG. 2, the spiral groove 22a is symbolically shown by a broken line for the sake of convenience.

Further, between the free end side end surface of the shaft 4 and the lower surface of the seal cap 8, there is a static pressure bearing portion 24 utilizing the internal pressure of oil increased by the spiral groove 22a of the thrust bearing portion 22. Composed.

A rotor magnet 14 is attached to the bracket 10.
An annular magnetic body 26 is provided at a position opposed to the axial direction. By generating a magnetic attraction force in the axial direction between the rotor magnet 14 and the magnetic body 26, the thrust of the rotor 6 is balanced with the floating pressure of the rotor 6 generated in the thrust bearing portion 22 and the static pressure bearing portion 24. The directional support is stabilized, and the occurrence of over-levitation in which the rotor 6 floats more than necessary is suppressed. The magnetic bias applied to the rotor 6 is, for example, the stator 12 and the rotor magnet 14
It is also possible to act by making the magnetic centers of and different in the axial direction.

FIG. 3 shows an enlarged cross-sectional view of the vicinity of the right cutout portion 6b in FIG. Hereinafter, the cutout portion 6b will be described with reference to FIG.
The configuration of the neighborhood will be described.

The radial dimension of the gap defined between the inner peripheral surface of the cylindrical wall 2a and the outer peripheral surface 6b1 of the notch 6b is that the outer peripheral surface 6b1 is formed into an inclined surface shape as described above. , Gradually taper upward in the axial direction (direction away from the base member 2). That is, the inner peripheral surface of the cylindrical wall 2a and the outer peripheral surface 6b1 of the cutout portion 6b cooperate with each other to form the taper seal portion 16. With respect to the oil held in the series of gaps, the surface tension of the oil and the external pressure are balanced only in the taper seal portion 16, and the interface between the oil and the air is formed in a meniscus shape.

A flange portion 2a1 is provided on the upper end of the cylindrical wall 2a so as to project radially outward. Also, the rotor 6
Then, the concave portion 6c is provided so as to be cut out radially outward of the cutout portion 6b, and an annular yoke 18 made of a magnetic material such as SUS is fixed to the concave portion 6c by laser welding. An annular rotor magnet 14 is fixed to the outer surface of the yoke 18, and the length of the yoke 18 in the axial direction is longer than the length of the rotor magnet 14 in the axial direction. As a result, the yoke 18 forms a magnetic circuit together with the rotor magnet 14, and an unnecessary magnetic field from the rotor magnet 14 toward the rotor 6 is suppressed. Further, by increasing the length of the yoke 18 in the axial direction, the yoke 18 can be appropriately fixed even when a thin rotor magnet having a thickness as small as a bead diameter of laser welding is used.

At the end of the yoke 18 on the fixed body side, a protrusion 18a is provided which protrudes toward the shaft 4 perpendicularly to the axial direction. The upper surface of the protruding portion 18a has a cylindrical wall 2
The lower surface of the flange portion 2a1 of a is opposed to the taper seal portion 16 via an axial gap that is continuous with the taper seal portion 16 and has a smaller gap size than the minimum radial gap of the taper seal portion 16. .

FIG. 4 is a cross-sectional view of the spindle motor 52 at the position of the arrow AA in FIG. In FIG. 4, only a portion inside the yoke 18 is shown, and as described above, the rotor 6 is provided around the shaft 4 via the radial dynamic pressure bearing portion 20, and between the rotor 6 and the yoke 18. It shows that the flange portion 2a1 is located at. In addition,
In FIG. 4, the vertical groove 20a forming the radial dynamic pressure bearing portion 20 is formed.
Are not shown.

The protruding portion 18a provided on the yoke 18 is
The flange portion 2a1 is provided on the cylindrical wall 2a so as to project in an annular shape toward the shaft 4 (inward in the radial direction), and to protrude outward in the annular direction in an annular shape. As a result, even if the spindle motor 52 is impacted and the rotor 6 (rotating body) moves in a direction away from the base member 2 and the bracket 10 (fixed body), the protruding portion 18a and the flange portion 2a1.
And abut, and the rotor 6 is locked (see FIG. 3). That is, the protruding portion 18a and the flange portion 2a1 form a retaining structure for the rotating body with respect to the fixed body.

As described above, in the spindle motor 52, the retaining structure is formed by the yoke 18 and the base member 2, so that it is smaller than the case where the retaining structure is provided in the bearing portion as in the conventional spindle motor. Can be easily converted. That is, in the spindle motor 52, the radial dynamic pressure bearing portion 20 and the retaining structure are not aligned on the same line in the axial direction by forming the retaining structure for the rotor 6 in the notch portion 6b. Therefore, the entire length of the shaft 4 can be effectively utilized as a bearing, and the spindle motor can be made thinner while maintaining the bearing rigidity.

Further, in the spindle motor 52, since it is not necessary to separately provide a member constituting the retaining structure, it is possible to reduce the manufacturing cost, and further, the retaining structure is provided outside the bearing portion. , Protruding portion 18a
Particles generated by the contact between the flange portion 2a1 and the flange portion 2a1 are prevented from entering the bearing portion, and the reliability of the spindle motor 52 can be improved.

By using the spindle motor 52 shown in FIG. 2 as the spindle motor of the disk drive device 50 shown in FIG. 1, downsizing of the disk drive device 50 and improvement of reliability can be realized.

FIG. 5 is a diagram showing another example of the retaining structure. In the spindle motor having the retaining structure shown in FIG. 5, a plurality of convex (pin-shaped) locking pins 2a2 protruding toward the yoke 18 are provided on the cylindrical wall 2a, and the yoke 18 is provided at the end portion on the fixed body side. It has an annular projecting portion 18 a that projects toward the shaft 4. Other configurations of the spindle motor are the same as those in FIGS. 2 to 4. In the retaining structure shown in FIG. 5, the locking pin 2a2 and the protruding portion 18a constitute a retaining structure, and when the rotating body and the fixed body move in the direction of separating from each other, the plurality of retaining pins 2a2 and the protruding portion are formed. 18
a and abut, and regulate the moving distance.

FIG. 6 is a diagram showing another example of the retaining structure. In FIG. 6, an annular flange portion 2a1 is provided on the cylindrical wall 2a.
And the yoke 18 has a plurality of projecting pins 18b that are convex (pin-shaped) toward the shaft 4. In the retaining structure shown in FIG. 6, the retaining structure is constituted by the annular flange portion 2a1 and the plurality of projecting pins 18b.

As shown in FIGS. 5 and 6, at least one of the structure (flange 2a1) on the base member 2 side and the structure (projection 18a) on the yoke 18 side of the retaining structure is provided in an annular shape. The shaft 4
It is possible to prevent particles from entering the surrounding bearing portion, and it is possible to easily prevent deterioration in performance of the bearing portion, seizure, and the like. Further, by making any of the configurations of the retaining structure into an annular shape, retaining can be easily realized at any rotation position of the rotating body.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments and various modifications can be made.

The above embodiment is a so-called inner rotor type in which the rotor magnet 14 is provided closer to the shaft 4 than the stator 12, but is a so-called outer rotor type in which the stator 12 is provided closer to the shaft 4 than the rotor magnet 14. It may be. The inner rotor type has a yoke 1 more than the outer rotor type.
Since the diameter of 8 is small, the retaining structure can be made compact.

The shape of the yoke 18 is not limited to the above-mentioned embodiment, and for example, as shown in FIG. 7, the yoke 18 may further have an annular protrusion 181 protruding outward in the radial direction. Good. In this case, the rotor magnet 14
Is fixed to the lower surface of the protrusion 181 and the outer surface of the yoke 18, and the protrusion 181 prevents the magnetic field of the rotor magnet 14 from unnecessarily leaking upward in FIG.

Although the yoke 18 is fixed to the rotor 6 by laser welding in the above embodiment, the yoke 18 may be fixed by resistance welding or by a method other than welding. For example, by applying an adhesive to the recess 6c of the rotor 6 and press-fitting the yoke 18, the yoke 18 can be fixed while preventing the adhesive from leaking to the notch 6b side. As a result, the adhesive is notched 6b.
It is possible to avoid a problem such as a defective rotation that may occur when the protrusion extends to the side.

Further, in the above-described embodiment, the length of the yoke 18 in the axial direction is longer than the length of the rotor magnet 14 in the axial direction, but the unnecessary leakage magnetic field of the rotor magnet 14 affects the characteristics of the spindle motor. If it is suppressed to the extent that it does not affect, it is not always necessary.

In the spindle motor, a member to which a rotor magnet which is a field magnet is fixed may be a fixed body, and a member to which a stator which is an armature is attached may be a rotating body.

In the above embodiment, the protruding portion 18a (or the protruding pin 18b) of the yoke 18 protrudes vertically inward with respect to the rotating shaft, and the flange portion 2a1 of the base member 2 is formed.
(Alternatively, the locking pin 2a2) also projects vertically to the outside with respect to the rotation axis, but these do not have to project exactly perpendicular to the rotation axis, and the cross-sectional shape may be changed as appropriate.
That is, the protruding portion 18a and the like protrude in the direction perpendicular to the rotation axis, and the flange portion 2a1 and the like also protrude in the perpendicular direction, so that the retaining structure is realized.

Further, the flange portion 2a1 (or the locking pin 2a2) does not have to be provided on the base member 2 and may be provided separately on the bracket 10.

Further, in the spindle motor shown in FIG. 2, the seal cap 8 is eliminated, and a taper shape is formed in which the gap widens toward the upper end between the outer peripheral surface of the shaft 4 and the inner peripheral surface of the rotor 6 in the axially outward direction. A gap portion may be formed, and a taper seal portion that holds the oil interface by surface tension may be formed at this portion. In this case, the rotor 6
The floating pressure is generated only in the thrust bearing portion 22.

The disk drive device 50 is not limited to a so-called hard disk device, but may be a device that drives an optical disk, a magneto-optical disk, or the like.

[0046]

According to the inventions of claims 1 to 6, it is possible to construct a retaining structure using a yoke, and it is possible to reduce the size of the motor.

According to the second aspect of the invention, the thrust bearing member can be used for the retaining structure.

According to the third aspect of the invention, it is possible to prevent the particles from entering around the central axis.

Further, in the invention of claim 4, the unnecessary leakage magnetic field of the field magnet can be further suppressed.

According to the invention of claim 7, a highly reliable disk device can be easily miniaturized.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an internal configuration of a disk drive device.

FIG. 2 is a vertical sectional view of a spindle motor.

FIG. 3 is an enlarged cross-sectional view in the vicinity of a cutout portion.

FIG. 4 is a transverse sectional view of the spindle motor.

FIG. 5 is a cross-sectional view showing another example of the spindle motor.

FIG. 6 is a transverse sectional view showing still another example of the spindle motor.

FIG. 7 is a diagram showing another example of a retaining structure.

[Explanation of symbols]

2 Base member 2a1 flange part 4 shafts 6 rotor 10 bracket 12 stator 14 rotor magnet 18 York 18a protrusion 50 disk drive 51 housing 52 Spindle motor 53 disc plate 57 Head moving mechanism

Continued front page    F-term (reference) 5D109 BA02 BA15 BA18 BA25 BB17                       BB21 BB22                 5H605 AA00 BB05 BB10 BB14 CC01                       CC02 CC04 DD03 EA07 EB02                 5H621 BB07 GA01 GA04 HH01 JK08                       JK15 JK19                 5H622 AA03 CA05 CA10 PP09

Claims (7)

[Claims] 1. An electric motor, comprising: a first member to which a field magnet arranged around a central axis is attached via a yoke; and a field member facing the field magnet and the field member. A second member to which an armature that generates a rotational force about the central axis is attached between the magnet and the magnet for magnetism, the first member being the central axis with respect to the second member. Is supported so as to be relatively rotatable about a center, and the yoke has a protruding portion that protrudes in a direction perpendicular to the central axis at an end portion on the second member side, and the second member is A motor having a locking portion that comes into contact with the protrusion when the first member moves in a direction away from the second member. 2. The motor according to claim 1, wherein the second member has a thrust bearing member, and the locking portion is a part of the thrust bearing member. 3. The motor according to claim 1, wherein at least one of the projecting portion and the locking portion is a circular ring centered on the central axis. 4. The motor according to claim 1, wherein the yoke is longer than the field magnet in the central axis direction. 5. The motor according to claim 1, wherein the field magnet is arranged closer to the central axis than the armature. 6. The motor according to claim 1, wherein the yoke is attached to the first member by laser welding. 7. A disk device in which a disc-shaped recording medium for recording information is mounted, wherein the housing accommodates the recording medium, and the recording medium is fixed inside the housing to rotate the recording medium. 7. A disk device comprising: the motor according to any one of 1 to 6; and an access unit that writes or reads information on the recording medium.