JP3786355B2 - Spindle motor and recording disk drive device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spindle motor, and more particularly to a spindle motor having a rotating member composed of a hub and a shaft fitted in a center hole thereof. The present invention further relates to a recording disk drive apparatus employing the spindle motor.
[0002]
[Prior art]
A recording disk drive device such as a hard disk has a spindle motor for rotational driving arranged concentrically with the recording disk. The spindle motor mainly includes a stationary member having an armature coil, a rotating member having a rotor magnet facing the coil, and a bearing mechanism that rotatably supports the rotating member on the stationary member.
[0003]
As an example of such a spindle motor, a shaft rotation type spindle motor is known. In this spindle motor, the rotating member has a hub and a shaft having one end fitted in the center hole thereof, and the stationary member has a hollow cylindrical sleeve that accommodates the shaft of the rotating member on the inner peripheral side. ing. The hub is generally a disk-shaped member, and a cylindrical portion extending in the axial direction is formed on the outer peripheral edge. A stator coil is provided on the inner peripheral side of the cylindrical portion, and a plurality of recording disks are fixed to the flange portion on the outer peripheral side. The recording disk fixing means includes a clamp member for clamping the recording disk to the end face of the flange and a screw member for fixing the recording disk to the hub. For this reason, the rotation member is formed with a screw hole for screwing the screw member. In addition, as a bearing mechanism, for example, a fluid dynamic pressure bearing is formed between the sleeve and the shaft.
[0004]
[Problems to be solved by the invention]
Due to the recent trend toward downsizing and thinning of devices such as personal computers on which recording disk drive devices are mounted, and the diversification of products used such as application to small devices such as digital cameras of recording disk drive devices, The spindle motor itself that is driven to rotate is also required to be reduced in size and thickness. Therefore, in the spindle motor, the hub, which is a rotating member, is becoming thinner.
[0005]
As the hub becomes thinner, screw holes for fixing the disk clamp to the rotating member cannot be formed in the hub, but are formed in the end face of the shaft. Then, the disk clamp is bent at the central portion by the screw member, so that a bending reaction force is applied to the inner peripheral portion of the recording disk from the outer peripheral portion. Therefore, the outer peripheral portion of the hub is always pushed to the opposite side of the clamp member by the clamping force from the disk clamp.
[0006]
When the clamping force acts in this way, the hub is bent and deformed. Therefore, there is a problem that accuracy (perpendicularity) between the hub and the shaft is deviated and RRO (Repeatable Run-Out) is deteriorated or the fastening between the hub and the shaft is disengaged.
In particular, when the hub is made thinner, the fastening section of the hub / shaft becomes shorter, so that the fastening strength between the shaft and the hub cannot be sufficiently obtained. Therefore, it is conceivable that the above problem becomes more remarkable.
[0007]
Various measures can be considered for the above-described problem of lowering the fastening strength between the shaft and the hub, but each measure includes a problem. For example, in the method of increasing the tightening allowance when the hub / shaft is press-fitted, there is a concern that the load on the hub / shaft (residual stress of fastening, etc.) is increased and plastic deformation occurs, which may deteriorate the rotational accuracy. . Further, in the method of reducing the clamping force, there is a concern that the recording disk is displaced or scattered.
[0008]
SUMMARY OF THE INVENTION An object of the present invention is to provide a spindle motor in which a screw hole for screwing a disk clamp is formed on one end face of a rotary shaft fastened to a center hole of a hub. The problem is to appropriately eliminate the problem of the hub / shaft fastening portion due to the clamping force.
[0009]
[Means for Solving the Problems]
The spindle motor described in claim 1 includes a stationary member, a hub, a shaft, a stator coil, and a rotor magnet. The stationary member has a hollow cylindrical sleeve. The hub includes a disk-shaped part in which a central hole is formed, and a cylindrical part protruding in the axial direction from the inner peripheral edge of the disk-shaped part. The shaft is a member arranged on the inner side in the radial direction of the inner peripheral surface of the sleeve, and one end is fitted to the inner peripheral surface of the cylindrical portion. A screw hole into which a screw member for deflecting the disk clamp is screwed is formed on the end surface of one end of the shaft. The bearing mechanism is a mechanism for rotatably supporting the hub and the shaft with respect to the stationary member. The stator coil is fixed to the stationary member. The rotor magnet is fixed to the hub so as to face the stator coil, and generates a rotating magnetic field in cooperation with the stator coil.
[0010]
In this spindle motor, in the recording disk driving apparatus, the screw member is screwed into the screw hole of the shaft to deflect the disk clamp. For this reason, the disk clamp clamps the recording disk between the hub.
By forming a screw hole in the shaft, the disk-shaped part of the hub can be thinned.However, this configuration allows the clamping force against the hub to press the outer peripheral part of the hub toward one side in the axial direction. ing. For this reason, it is considered that the hub is flexibly deformed by the clamp, the hub is inclined at the fitting portion with respect to the shaft, and the fastening is easily released at the front end side in the axial direction of the fitting portion.
[0011]
However, in this spindle motor, the hub tubular portion is fastened to the shaft, so that a sufficient contact area between the hub and the shaft can be secured, and sufficient hub / shaft fastening strength can be obtained. Therefore, it is difficult for the hub and the shaft to be unfastened when a clamping force is applied.
According to a second aspect of the present invention, in the spindle motor according to the first aspect, the bearing mechanism holds the lubricating fluid between the outer peripheral surface of the cylindrical portion and the radial inner peripheral surface of the sleeve, and induces dynamic pressure in the lubricating fluid. The first radial bearing portion configured by providing the dynamic pressure generating groove is included.
[0012]
In this spindle motor, since the first radial bearing portion is formed on the outer peripheral surface of the cylindrical portion of the hub, the diameter of the radial bearing portion is larger than the conventional one. For this reason, peripheral speed increases in a radial bearing part, and the generated dynamic pressure becomes large.
Also, simply setting the fastening section long in order to improve the fastening strength between the hub and the shaft limits the dimensions of the radial bearing provided near the hub / shaft fastening part. It becomes difficult to secure necessary rotational support force such as bearing rigidity. On the other hand, in this spindle motor configuration, the first radial bearing portion is formed on the outer peripheral surface of the cylindrical portion of the hub, so that sufficient bearing rigidity can be ensured.
[0013]
According to a third aspect of the present invention, in the spindle motor according to the second aspect, the bearing mechanism holds the lubricating oil between a portion of the outer peripheral surface of the shaft that is not covered by the cylindrical portion of the hub and a radial inner peripheral surface of the sleeve. And further includes a second radial bearing portion configured by providing a dynamic pressure generating groove for inducing dynamic pressure in the lubricating fluid.
In this spindle motor, the diameter of the second radial bearing portion is smaller than the diameter of the first radial bearing portion, which is the same as the conventional one, but the radial dynamic pressure is large in the entire bearing mechanism.
[0014]
According to a fourth aspect of the present invention, in the spindle motor according to the first aspect, the bearing mechanism holds the lubricating fluid between the outer peripheral surface of the cylindrical portion and the two radial inner peripheral surfaces of the sleeve, and the dynamic pressure is applied to the lubricating fluid. The first and second radial bearing portions are provided by providing a dynamic pressure generating groove for inducing the above.
In this spindle motor, since the first and second radial bearing portions are formed on the outer peripheral surface of the cylindrical portion, the diameter of the radial bearing portion is larger than the conventional one. For this reason, peripheral speed increases in a radial bearing part, and the generated dynamic pressure becomes large.
[0015]
According to a fifth aspect of the present invention, in the spindle motor according to the fourth aspect, the outer diameters of the portions constituting the first and second radial bearings on the outer peripheral surface of the cylindrical portion are the same, and the two radial inner peripheral surfaces of the sleeve are the same. The inner diameter is the same.
In this spindle motor, the coaxiality of the two radial bearing portions is improved.
According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the bearing mechanism holds the lubricating fluid between the thrust surface of the shaft and the thrust surface of the sleeve, and applies dynamic pressure to the lubricating fluid. It further includes a thrust bearing portion configured by providing an inductive dynamic pressure generating groove.
[0016]
In this spindle motor, the thrust dynamic pressure can be obtained by the thrust bearing portion.
According to a seventh aspect of the present invention, there is provided a recording disk drive device including a housing, the spindle motor according to any one of the first to sixth aspects fixed to the inside of the housing, and information fixed to a disk-shaped portion of the hub. A disc-shaped recording medium capable of recording, and information access means for writing or reading information at a required position of the recording medium are provided.
[0017]
In this recording disk drive apparatus, the recording medium can be stably rotated by providing the spindle motor with the improved fastening strength between the shaft and the hub.
According to an eighth aspect of the present invention, there is provided a recording disk drive device according to the seventh aspect, further comprising: a screw member that is screwed into a screw hole of the shaft; and a disk clamp that is bent by the screw member and clamps the recording medium to the hub. ing.
[0018]
In this recording disk drive apparatus, the recording medium can be stably rotated by providing the spindle motor with the improved fastening strength between the shaft and the hub.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
1. First embodiment
(1) Overall configuration of spindle motor
FIG. 1 is a longitudinal sectional view schematically showing a schematic configuration of a spindle motor 1 as an embodiment of the present invention. The spindle motor 1 is a recording disk driving spindle motor and constitutes a part of a recording disk driving device such as a hard disk.
[0020]
Note that OO shown in FIG. 1 is the rotation axis of the spindle motor 1. In the description of the present embodiment, the vertical direction in FIG. 1 is referred to as the “axis vertical direction” for convenience, but the direction in the actual mounting state of the spindle motor 1 is not limited.
In FIG. 1, the spindle motor 1 mainly includes a stationary member 2, a rotating member 3, and a bearing mechanism 4 for rotatably supporting the rotating member 3 on the stationary member 2. The spindle motor 1 further includes a stator 6 fixed to the stationary member 2 and a rotor magnet 7 fixed to the rotating member 3. A magnet for applying a rotational force to the rotating member 3 by both members. A circuit unit is configured.
[0021]
(2) Stationary member
The stationary member 2 includes a bracket 10 and a sleeve 11 fixed in the central opening of the bracket 10. More specifically, a cylindrical portion 10a extending upward in the axial direction is formed at the central opening edge of the bracket 10, and the outer peripheral surface of the sleeve 11 is fitted to the inner peripheral surface thereof. The stator 6 is fixed to the outer peripheral surface of the cylindrical portion 10a.
[0022]
The sleeve 11 is a hollow cylindrical member, and a through hole 51 penetrating in the axial direction is formed at a substantially central portion thereof. The inner peripheral surface of the through hole 51 of the sleeve 11 includes a first radial inner peripheral surface 53, a second radial inner peripheral surface 54, and a lower inner peripheral surface 55 arranged in the following order from the upper side to the lower side in the axial direction. Have. The first and second radial inner peripheral surfaces 53 and 54 constitute each radial bearing portion of the bearing mechanism 4 (described later). The lower end of the through hole 51 of the sleeve 11 is closed by the thrust cover 12.
[0023]
(3) Rotating member
The rotating member 3 is a member that is rotatably supported by the sleeve 11 via the bearing mechanism 4, and is located on the outer peripheral side of the rotor hub 14 on which the recording disk 83 is placed, and on the inner peripheral side of the rotor hub 14. And a shaft 15 supported by the sleeve 11 via the bearing mechanism 4.
[0024]
The rotor hub 14 is a substantially disk-shaped member, and is disposed close to the stationary member 2 and the stator 6. More specifically, the rotor hub 14 mainly includes a disc-shaped portion 31, a cylindrical portion 32 extending downward in the axial direction from the outer peripheral edge of the disc-shaped portion 31, and an axis line from the inner peripheral edge of the disc-shaped portion 31. It is comprised from the cylindrical part 33 extended in the direction lower side. The cylindrical portions 32 and 33 are both cylindrical.
[0025]
The rotor magnet 7 is fixed to the inner peripheral surface of the cylindrical portion 32 by means such as adhesion. The rotor magnet 7 is arranged to face the stator 6 with a small gap in the radial direction, and generates a rotating magnetic field in cooperation with the stator 6. That is, when the coil of the stator 6 is energized, torque acts on the rotating member 3 due to electromagnetic interaction between the stator 6 and the rotor magnet 7.
[0026]
A flange portion 34 is formed at the distal end portion of the cylindrical portion 32 so as to extend to the outer peripheral side. The flange portion 34 has an axial upper end surface 35 for receiving a clamping force from a disk clamp 88 described later.
(4) Hub and shaft fastening structure
The hub 14 and the shaft 15 are fastened together by fitting the upper end of the shaft 15 into the center hole of the hub 14, that is, the inner peripheral surface thereof. More specifically, as shown in FIG. 2, the outer peripheral surface 42 of the upper portion 41 of the shaft 15 is press-fitted into the inner peripheral surface 38 of the cylindrical portion 33. Note that an adhesive may be supplied between the peripheral surfaces to improve the fastening strength.
[0027]
A stepped portion 43 is formed on the outer peripheral side of the tip of the upper portion 41 of the shaft 15. The stepped portion 43 has an axially upper end surface 44 and an outer peripheral surface 45. Therefore, the portion where the stepped portion 43 is formed is a cylindrical portion whose radial thickness is shorter than other portions. . An inner peripheral protrusion 36 is formed on the upper portion of the inner periphery of the hub 14 in the axial direction so as to correspond to the stepped portion 43. The protruding portion 36 is in contact with the stepped portion 43, whereby the hub 14 and the shaft 15 are positioned in the axial direction, and further, the shaft 15 is prevented from slipping out from the hub 14 in the axial direction.
[0028]
The fastening structure described above will be described in more detail. The cylindrical portion 33 is a portion protruding from the lower end surface in the axial direction of the disc-like portion 31, and the entire inner peripheral surface thereof is the outer peripheral surface 42 of the shaft 15. It is in close contact with.
In the fastening structure described above, since the shaft 15 is fitted to the tubular portion 33 of the hub 14, the fastening section / contact area is increased as compared with the conventional case, and the fastening strength is improved. Moreover, since the cylindrical part 33 of the hub 14 is fastened to the thick part (upper part 41) of the shaft 15, compared with the conventional example fastened to the thin part in which the step part 43 is formed, The allowance can be increased. That is, the fastening strength between the hub 14 and the shaft 15 can be further improved.
[0029]
Since the fastening strength between the hub 14 and the shaft 15 is improved in this way, even when a radial impact is applied to the hub 14, the accuracy (perpendicularity) between the hub and the shaft is less likely to be distorted.
(5) Bearing mechanism
The bearing mechanism 4 is a hydrodynamic bearing mechanism for rotatably supporting the rotating member 3 with respect to the stationary member 2, more specifically, the hub 14 and the shaft 15 with respect to the sleeve 11 via a lubricating fluid. It is. The bearing mechanism 4 includes first and second radial bearing portions 21 and 22 and first and second thrust bearing portions 23 and 24. Hereinafter, the structure of each bearing part 21-24 is demonstrated, touching the structure of the sleeve 11, the hub 14, and the shaft 15. FIG.
[0030]
(1) Radial bearing
As shown in FIG. 2, the first radial inner peripheral surface 53 of the sleeve 11 faces the outer peripheral surface 37 of the cylindrical portion 33 so as to secure a radial minute gap in which the lubricating fluid 8 is held. . The first radial inner peripheral surface 53 is formed with a herringbone dynamic pressure generating groove for generating dynamic pressure in the lubricating fluid 8. Thus, the 1st radial bearing part 21 is comprised by the 1st radial inner peripheral surface 53 of the sleeve 11, the outer peripheral surface 37 of the cylindrical part 33, and the lubricating fluid 8 between them.
[0031]
The second radial inner peripheral surface 54 of the sleeve 11 has a smaller diameter than the first radial inner peripheral surface 53 and is a lower portion in the axial direction of the outer peripheral surface 42 of the shaft 15 (the portion not covered by the cylindrical portion 33 of the hub 14). ) So as to secure a radial minute gap in which the lubricating fluid 8 is held. A herringbone dynamic pressure generating groove for generating dynamic pressure in the lubricating fluid 8 is formed in the second radial inner peripheral surface 54. Thus, the second radial bearing portion 22 is configured by the second radial inner peripheral surface 54 of the sleeve 11, the outer peripheral surface 42 of the shaft 15, and the lubricating fluid 8 therebetween.
[0032]
As described above, since the first radial bearing portion 21 is formed on the outer peripheral surface of the cylindrical portion 33 of the hub 14, the radius r1 of the first radial bearing portion 21 is the radius r2 of the second radial bearing portion 22. It is larger than Therefore, in the 1st radial bearing part 21, peripheral speed increases and the generated dynamic pressure becomes large. In addition, if there is a margin in the generated dynamic pressure, the gap between the cylindrical part and the sleeve can be increased, so the required accuracy for processing is eased, the yield is improved, the processing cost is reduced, etc. It is possible to contribute to cost reduction.
[0033]
The radius r2 of the second radial bearing portion 22 is equal to the outer peripheral surface 42 of the shaft 15 and is therefore the same size as the conventional one, but since the radius r1 of the first radial bearing portion 21 is large, the bearing mechanism The radial dynamic pressure is large in all four.
In addition, simply setting the fastening section to be long in order to improve the fastening strength between the hub and the shaft limits the dimensions because the radial bearing part is provided in the vicinity of the fastening part of the hub / shaft. As a result, it becomes difficult to secure necessary rotational support force such as bearing rigidity in the radial bearing portion. On the other hand, in the configuration of the spindle motor 1, since the first radial bearing portion 21 is formed on the outer peripheral surface of the cylindrical portion 33 of the hub 14, sufficient bearing rigidity is ensured after sufficiently securing a fastening section. can do.
[0034]
(2) Thrust bearing
The lower inner peripheral surface 55 of the sleeve 11 forms a stepped portion 52 having a larger diameter than the first and second radial inner peripheral surfaces 53 and 54 at the lower end of the through hole 51. That is, the stepped portion 52 has a thrust surface 56 that faces downward in the axial direction around the through-hole 51 and the lower inner peripheral surface 55 described above.
[0035]
A thrust flange 46 is formed at the lower end of the shaft 15. The thrust flange 46 is a disk-shaped portion that protrudes radially outward from the lower end of the shaft 15, and is disposed in the step portion 52 close to the thrust surface 56. The thrust flange 46 has a first thrust surface 47 facing the thrust surface 56 of the sleeve 11 and a second thrust surface 48 facing the opposite side, that is, the thrust surface 12 a side of the thrust cover 12.
[0036]
The first thrust surface 47 and the second thrust surface 48 of the thrust flange 46 are respectively formed with herringbone dynamic pressure generating grooves for generating dynamic pressure in the lubricating fluid as the shaft 15 rotates. Yes. Thus, the first thrust bearing portion 23 is formed by the thrust surface 56 of the sleeve 11, the first thrust surface 47 of the thrust flange 46, and the lubricating fluid 8 therebetween. Further, the second thrust bearing portion 24 is constituted by the second thrust surface 48 of the thrust flange 46, the thrust surface 12a of the thrust cover 12, and the lubricating fluid 8 therebetween.
[0037]
(6) Configuration of hard disk device
Although one embodiment of the spindle motor 1 for driving the recording disk according to the present invention has been described above, a hard disk device as a recording disk driving apparatus having the spindle motor 1 according to the present invention will be described as an example.
FIG. 5 shows a schematic diagram of an internal configuration of a general hard disk device 80. The inside of the housing 81 forms a clean space with extremely little dust and the like, and the above-described spindle motor 1 on which a disc-shaped recording disk 83 for storing information is mounted is installed. . In addition, a magnetic head moving mechanism 87 for reading / writing information from / to the recording disk 83 is disposed inside the housing 81. The magnetic head moving mechanism 87 includes a head 86 for reading / writing information on the recording disk, and this head. The supporting arm 85 and the actuator unit 84 that moves the head and the arm to required positions on the disk are configured.
[0038]
(7) Clamp structure
As shown in FIG. 1, the recording disk 83 is attached to the spindle motor 1 by a disk clamp 88 and a clamp screw 89. The recording disk 83 is three members arranged side by side in the axial direction, and the inner peripheral surface is fitted to the outer peripheral surface of the cylindrical portion 32 of the hub 14. The lowermost recording disk 83 is in contact with the axially upper end surface 35 of the flange portion 34 of the hub 14, and spacers 90 are disposed between the inner peripheral ends of the recording disks 83.
[0039]
The disc clamp 88 is a disc-shaped leaf spring member made of, for example, stainless steel, and has a curved shape with a central portion protruding upward in the axial direction in a free state. The disk clamp 88 is disposed close to the upper side in the axial direction of the hub 14. A central hole 88a is formed at the center of the disc clamp 88, and the inner peripheral edge thereof is a tapered surface 88b that opens upward in the axial direction. Further, a protruding portion 88 c that extends downward in the axial direction and contacts the side surface of the uppermost recording disc 83 is formed on the outer peripheral edge of the disc clamp 88.
[0040]
A screw hole 49 is formed in the upper end surface of the shaft 15 so as to extend in the axial direction. The clamp screw 89 is screwed into the screw hole 49, and the head portion 89 a abuts against the tapered surface 88 b of the disc clamp 88 in a complementary manner. As described above, the disc clamp 88 is bent so that the central portion thereof is urged downward in the axial direction with respect to the shaft 15 by the clamp screw 89 to become a flat plate shape, and the disc clamp 88 records the deflection reaction force. The disc 83 is given. In other words, the projecting portion 88 c strongly presses the inner peripheral portion of each recording disk 83 against the flange portion 34 of the hub 14.
[0041]
As described above, since the clamp screw 89 for fixing the disc clamp 88 is fixed to the shaft 15, the clamping force causes the hub 14 to bend and deform as compared with the case where the clamp screw 89 is fixed to the hub 14. To work. Specifically, the hub 14 is deformed so that the hub 14 is inclined with respect to the shaft 15 and the upper part of the fastening inner peripheral surface of the hub 14 is separated from the outer peripheral surface of the shaft 15 by moving the outer peripheral portion of the hub 14 downward in the axial direction. It is supposed to be. However, in this embodiment, since the fastening strength of both is improved by the cylindrical part 33 of the hub 14, the malfunction due to the clamping force hardly occurs. Specifically, RRO deterioration and disconnection between the hub and the shaft are unlikely to occur.
[0042]
2. Second embodiment
In this embodiment, the basic structure of the spindle motor 1 is the same as that of the above embodiment. Therefore, only the part of a different structure is demonstrated here.
As shown in FIG. 3, the hub 14 and the shaft 15 are positioned in the axial direction by providing an inner peripheral side protruding portion 39 on the inner peripheral edge of the hub 14 and bringing the upper end surface of the shaft 15 into contact therewith. .
[0043]
In this embodiment, the inner circumferential surface of the disk-shaped portion 31 of the hub 14 and the upper portion in the axial direction of the inner circumferential surface of the tubular portion 33 are fastened to the outer circumferential surface 42 of the upper portion 41 of the shaft 15. An inner peripheral surface 38A is formed. That is, the diameter of the lower portion 38B of the inner peripheral surface of the cylindrical portion 33 is larger than the outer diameter of the upper portion 41 of the shaft 15, and a minute amount is formed between the lower portion 38B of the inner peripheral surface and the outer peripheral surface 42. A gap is secured. As described above, unlike the embodiment, the cylindrical portion 33 is in close contact with the outer peripheral surface 42 of the shaft 15.
[0044]
3. Third embodiment
In this embodiment, the basic structure of the spindle motor 1 is the same as that of the above embodiment. Therefore, only the part of a different structure is demonstrated here.
As shown in FIG. 4, the arrangement of the cylindrical portion 133 of the hub 114 covers the entire outer peripheral surface of the shaft 115. As a result, the first radial bearing portion 121 and the second radial bearing portion 122 are formed by the outer peripheral surface 137 of the cylindrical portion 133.
[0045]
As described above, since the first and second radial bearing portions 121 and 122 are formed on the outer peripheral surface of the cylindrical portion 133 of the hub 114, the outer diameter of the shaft 115 is equivalent to the conventional one. The radius r1 of the first and second radial bearing portions 121 and 122 is larger than the radius r2 of the conventional radial bearing portion. Therefore, in the 1st and 2nd radial bearing parts 121 and 122, peripheral speed increases and generated dynamic pressure becomes large. In addition, if there is a margin in the generated dynamic pressure, the gap between the cylindrical part and the sleeve can be increased, so the required accuracy for processing is eased, the yield is improved, the processing cost is reduced, etc. It is possible to contribute to cost reduction.
[0046]
Furthermore, since the outer peripheral surface 137 of the cylindrical portion 133 and the inner peripheral surface 153 of the sleeve 111 have the same diameter at the portions forming the first radial bearing portion 121 and the second radial bearing portion 122, the first radial bearing portion. 121 and the 2nd radial bearing part 122 are arrange | positioned in the same radial direction position. As a result, the coaxiality of the first radial bearing portion 121 and the second radial bearing portion 122 is improved.
[0047]
4). Other embodiments
The present invention is not limited to the above-described embodiment, and various changes and modifications can be made without departing from the scope of the present invention.
Specifically, the present invention is not limited to the dynamic pressure bearing, the spindle motor, or the recording disk driving device shown in the above embodiment.
[0048]
In addition to the lubricating oil, air may be used as the lubricating fluid.
Furthermore, the shape and the formation position of the dynamic pressure generating groove constituting the radial thrust bearing portion of the dynamic pressure bearing are not limited to the above embodiment.
[0049]
【The invention's effect】
In the spindle motor according to the first aspect, in the recording disk device, the screw member is screwed into the screw hole of the shaft to deflect the disk clamp. For this reason, the disk clamp clamps the recording disk between the hub.
[0050]
By forming a screw hole in the shaft, the disk-shaped part of the hub can be thinned.However, this configuration allows the clamping force against the hub to press the outer peripheral part of the hub toward one side in the axial direction. ing. For this reason, it is considered that the hub is flexibly deformed by the clamp, the hub is inclined at the fitting portion with respect to the shaft, and the fastening is easily released at the front end side in the axial direction of the fitting portion.
[0051]
However, in this recording disk device, the hub tubular portion is fastened to the shaft, so that a sufficient contact area between the hub and the shaft can be secured, and sufficient hub / shaft fastening strength can be obtained. . Therefore, it is difficult for the hub and the shaft to be unfastened when a clamping force is applied.
According to a second aspect of the present invention, in the spindle motor according to the first aspect, since the first radial bearing portion is formed on the outer peripheral surface of the cylindrical portion of the hub, the diameter of the radial bearing portion is larger than that of the conventional one. . For this reason, peripheral speed increases in a radial bearing part, and the generated dynamic pressure becomes large.
[0052]
Also, simply setting the fastening section long in order to improve the fastening strength between the hub and the shaft limits the dimensions of the radial bearing provided near the hub / shaft fastening part. It becomes difficult to secure necessary rotational support force such as bearing rigidity. On the other hand, in this spindle motor configuration, the first radial bearing portion is formed on the outer peripheral surface of the cylindrical portion of the hub, so that sufficient bearing rigidity can be ensured.
[0053]
In the spindle motor according to a third aspect, in the second aspect, the diameter of the second radial bearing portion is smaller than the diameter of the first radial bearing portion, and is equal to the conventional one, but the radial dynamic pressure is increased in the entire bearing mechanism. Yes.
According to a fourth aspect of the present invention, in the spindle motor according to the first aspect, since the first and second radial bearing portions are formed on the outer peripheral surface of the cylindrical portion, the diameter of the radial bearing portion is larger than that of the conventional one. Yes. For this reason, peripheral speed increases in a radial bearing part, and the generated dynamic pressure becomes large.
[0054]
According to a fifth aspect of the present invention, in the spindle motor according to the fourth aspect, the outer diameters of the portions constituting the first and second radial bearings on the outer peripheral surface of the cylindrical portion are the same, and the two radial inner peripheral surfaces of the sleeve are the same. Since the inner diameter is the same, the coaxiality of the two radial bearing portions is improved.
The spindle motor according to claim 6, wherein the bearing mechanism further includes a thrust bearing portion between the thrust surface of the shaft and the thrust surface of the sleeve. Thrust dynamic pressure can be generated by the portion.
[0055]
In the recording disk drive apparatus according to the seventh aspect, the recording medium can be stably rotated by including the spindle motor having the improved fastening strength between the shaft and the hub.
In the recording disk drive apparatus according to the eighth aspect of the present invention, the recording medium can be stably rotated by including the spindle motor having the improved fastening strength between the shaft and the hub.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view of a spindle motor as a first embodiment of the present invention.
2 is a schematic longitudinal sectional view of a fastening portion of a hub and a shaft and a first radial bearing portion, and is a partially enlarged view of FIG. 1;
FIG. 3 is a schematic longitudinal sectional view of a fastening portion between a hub and a shaft and a first radial bearing portion in a second embodiment.
FIG. 4 is a schematic vertical sectional view of a spindle motor as a third embodiment.
FIG. 5 is a schematic configuration diagram of a general hard disk device.
[Explanation of symbols]
1 Spindle motor
11 Sleeve
14 Hub
15 shaft
21 First radial bearing
33 Cylindrical part
38 Inner peripheral surface
41 Upper side
42 outer peripheral surface
49 Screw hole
88 Disc clamp (clamp member)
89 Screw member

Claims (8)

A spindle motor used in a recording disk drive device,
A stationary member having a hollow cylindrical sleeve;
A hub having a disk-shaped part in which a central hole is formed, and a cylindrical part protruding in an axial direction from the inner periphery of the disk-shaped part;
A member disposed radially inside the sleeve, one end of which is fitted to the inner peripheral surface of the cylindrical portion, and a screw member is screwed to the end surface of the one end to bend the disk clamp. A shaft formed with a screw hole to be
A bearing mechanism for rotatably supporting the hub and the shaft with respect to the stationary member;
A stator coil fixed to the stationary member;
A rotor magnet fixed to the hub so as to face the stator coil, and generating a rotating magnetic field in cooperation with the stator coil;
With spindle motor. The bearing mechanism is configured by holding a lubricating fluid between an outer peripheral surface of the cylindrical portion and a radial inner peripheral surface of the sleeve and providing a dynamic pressure generating groove for inducing dynamic pressure in the lubricating fluid. The spindle motor according to claim 1, comprising a first radial bearing portion formed. The bearing mechanism holds lubricating oil between a portion of the outer peripheral surface of the shaft not covered by the cylindrical portion of the hub and a radial inner peripheral surface of the sleeve, and induces dynamic pressure in the lubricating fluid. The spindle motor according to claim 2, further comprising a second radial bearing portion configured by providing a dynamic pressure generating groove. The bearing mechanism holds a lubricating fluid between the outer peripheral surface of the cylindrical portion and the two radial inner peripheral surfaces of the sleeve, and provides a dynamic pressure generating groove for inducing dynamic pressure in the lubricating fluid. 2. The spindle motor according to claim 1, comprising first and second radial bearing portions configured as follows. The outer diameters of the portions constituting the first and second radial bearing portions on the outer peripheral surface of the cylindrical portion are the same,
The spindle motor according to claim 4, wherein inner diameters of the two radial inner peripheral surfaces of the sleeve are the same. The bearing mechanism is configured to hold a lubricating fluid between a thrust surface of the shaft and a thrust surface of the sleeve, and to provide a dynamic pressure generating groove for inducing dynamic pressure in the lubricating fluid. The spindle motor according to claim 1, further comprising a portion. A housing;
The spindle motor according to any one of claims 1 to 6, which is fixed inside the housing;
A disk-shaped recording medium fixed to the disk-shaped portion of the hub and capable of recording information; and an information access means for writing or reading information at a required position of the recording medium;
A recording disk drive device comprising: A screw member screwed into the screw hole of the shaft;
A disk clamp that is bent by the screw member and clamps the recording medium to the hub;
The recording disk drive device according to claim 7, further comprising:

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