JP2003139131A - Bearing device and motor using the bearing, and disc device using the motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To widen the region of a seal part without damaging sealing ability as bearing performance is maintained and simultaneously decrease thickness, in a slide system bearing device. SOLUTION: The bearing part is provided with: a shaft member 11 having a shaft part 111; a sleeve member 12 situated opposite to the shaft part 11 with a micro-gap X therebetween; a lubricator fluid L filled in the micro-gap X; and a seal member 15 having an insertion hole 15a in which the shaft part 111 is inserted and adhered to an upper end face 12b of the sleeve member 12. A gap between an insertion hole 15a and the shaft part 111 is radially enlarged to form a seal part 150, and the sleeve member 12 and the shaft member 11 are relatively revolvably supported. The seal part 150 is divided into an inside region 150a and an outside region 150b by an annular member 17 situated coaxially with the shaft part 111, the two regions 150 and 150b are intercommunicated and continuously connected to the upper end of the shaft gap X with the regions having shapes to which respective capillary phenomena occur. The two regions 150a and 150b allow the fluctuations of interfaces Lsa and Lsb, which holding a part of the lubrication fluid L and the respective interfaces Lsa and Lsb.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing device, a motor using the same, and a disk device using the motor, and in particular, a lubricating fluid is interposed in a minute gap between a shaft member and a sleeve member. The present invention relates to a bearing device that rotatably supports both members, a motor including the bearing device, and a disk device including the motor.

[0002]

2. Description of the Related Art Generally, types of bearing devices are roughly classified into a sliding type and a rolling type. In the former, since the rotating side member and the stationary side member are supported by the sliding contact so that they can rotate relative to each other, the structure is relatively simple and is applicable to various axis rotating devices without being restricted in size. It is customary to interpose a lubricating fluid in the mutual contact area in order to reduce the resistance which tends to become excessive. On the other hand, the latter has a characteristic that it is supported by rolling contact, so that it is difficult to apply it to a small apparatus which has a complicated structure and particularly requires a high-speed rotation range.

By the way, a hard disk drive (HD
D) and high-capacity floppy disk drives (FDD) have become extremely high-capacity and miniaturized year by year, and the spindle motor used in them has a life and quietness that can withstand high-speed rotation, Excellent runout accuracy,
Furthermore, compactness that achieves miniaturization is required. Therefore, as a bearing means for such a spindle motor, a sliding type bearing device is applied when it is extremely difficult to satisfy such a requirement with a rolling type bearing device such as a ball bearing. Hereinafter, this sliding type bearing device will be examined.

Here, in order to further satisfy the above-mentioned requirements, a structure in which a lubricating fluid is only interposed in the contact region to reduce the sliding friction resistance is not provided, but a structure between the rotating side member and the stationary side member is provided. It is preferable to provide a so-called dynamic pressure type bearing device that supports in a contact region in a non-contact manner by using the fluid dynamic pressure generated in the intervening lubricating fluid. For example, the structure of the dynamic pressure type bearing device is roughly that a shaft member having a thrust plate portion, a sleeve member arranged facing the shaft member with a minute gap, and the minute gap filled with the sleeve member. It comprises a lubricating fluid and a dynamic pressure generating groove provided on the opposing surfaces forming a minute gap for inducing a fluid dynamic pressure in the lubricating fluid when the motor rotates. In the dynamic pressure type bearing device having such a basic structure, in order to meet the market demand for further reliability and durability of the device and cost reduction due to the simplification of the structure, a small amount between the shaft member and the sleeve member is required. A so-called full-fill structure has been developed in which the entire gap is filled with a lubricating fluid. A conventional example of a dynamic pressure type bearing device using the full-fill structure is shown in FIG.
Shown in.

In the bearing device of FIG. 9, the sleeve support member 1
A through hole 131 is formed in the center of the shaft 3 in the axial direction, and a fitting groove portion 132 having a diameter larger than the inner diameter of the through hole 131 is formed at the lower end of the sleeve supporting member 13. The two radial dynamic pressure generating grooves 121a and 121b are axially separated from each other on the inner peripheral surface of the through hole 131 to form the inner peripheral surface 12a.
And the thrust dynamic pressure generating groove 12 is formed on the lower end surface.
1c is formed, and the length in the axial direction is the sleeve support member 13
A hollow cylindrical sleeve member 12 made of a shorter porous sintered body is fixed.

On the other hand, the shaft member 11 comprises a shaft portion 111 and a thrust plate portion 112 formed at the lower end of the shaft portion 111. Then, until the upper surface of the thrust plate portion 112 contacts the lower end surface of the sleeve member 12, the shaft member 11 is inserted into the hollow portion formed by the inner peripheral surface 12a of the sleeve member 12.
The shaft portion 111 of is inserted through a certain minute gap (hereinafter, also referred to as “shaft portion gap”) so as to seal the lower opening of the through hole 131 formed in the sleeve support member 13. The thrust bush member 14 having the thrust dynamic pressure generating groove 141 formed on the upper surface is attached to the fitting groove portion 132. On the other hand, the shaft portion 111 is provided in the upper opening of the through hole 131.
An annular seal member 15 having an insertion hole 15a for inserting
However, the upper surface 15b and the upper end surface 1 of the sleeve supporting member 13
The lower surface 15c and the upper end surface 12b of the sleeve member 12 are brought into close contact with each other so that they are flush with the through hole 131.
Is fixed to the inner surface of the.

The inside of the through hole 131 surrounded by the sleeve support member 13, the thrust bush member 14, and the seal member 15 is filled with a lubricating fluid (not shown).
That is, between the sleeve member 12 and the shaft portion 111, and between the thrust plate portion 112 and the thrust bush member 1.
4 and a continuous hole formed inside the sleeve member 12 are filled with a lubricating fluid.

In the bearing device having the above structure, the shaft member 11
The radial load of No. 1 is two herringbone type radial dynamic pressure generating grooves 1 formed on the inner peripheral surface of the sleeve member 12.
On the other hand, due to the fluid dynamic pressure generated at 21a and 121b, the thrust load on the other hand is generated by the spiral dynamic pressure generation grooves 121c and 141 formed on the lower end surface of the sleeve member 12 and the surface of the thrust bush member 14. The shaft member 111 and the sleeve member 12 are relatively rotatable with each other.

Here, the role and structure of the seal member 15 will be described with reference to FIG. Figure 10
FIG. 10 is an enlarged cross-sectional view of a main part of the bearing device of FIG. 9.
A taper surface 117 is formed on the shaft portion 111 facing the inner peripheral surface of the insertion hole 15a of the seal member 15 with a small gap so as to gradually reduce the shaft portion outer diameter upward in the axial direction. The tapered seal portion 150 is formed by the gap formed by the tapered surface 117 and the inner peripheral surface of the insertion hole 15a of the seal member 15 and gradually increasing axially upward.
Is configured. The lower end of the seal portion 150 is continuous with the upper end of the shaft portion gap X formed by the inner peripheral surface 12a of the sleeve member 12 and the shaft portion 111, and holds the lubricating fluid L therein.

Therefore, the seal portion 150 can be brought into a state in which the lubricating fluid is constantly held and replenished in the contact region (the shaft gap X in FIG. 10), and the lubricating fluid L changes due to the temperature change. When thermal expansion / contraction causes the interface Ls to fluctuate (broken line in the figure), it also serves as a buffer that allows this interface fluctuation. Further, by making the taper shape, a capillary phenomenon is caused, and it is possible to prevent the lubricating fluid L from scattering or leaking out of the device. In addition, the seal member 15
Since the upper end surface 12b of the sleeve member 12 is isolated from the atmosphere by the above, even if the sleeve member 12 is made of a porous sintered body, the air in the atmosphere is inadvertently sucked into the inside of the lubricating fluid. It is possible to prevent air from being entrapped or the lubricating fluid existing therein to be inadvertently evaporated into the atmosphere. In this way, the seal member 15
Plays an extremely important role from the viewpoint of maintaining the filled state of the lubricating fluid so that the amount of the lubricating fluid in the contact area is not insufficient, and is essential for providing long-term smooth and stable rotation operation of the bearing device. There is no such thing.

What is important here is that the volume of the seal portion 150 needs to be large enough to allow the interface fluctuation of the lubricating fluid due to thermal expansion / contraction.
In particular, when the sleeve member 12 is made of a porous sintered body, a large amount of lubricating fluid is filled as a whole, and the interface fluctuation amount inevitably becomes large. It needs to be set significantly larger.

[0012]

However, in order to secure the volume of the seal portion 150 in the conventional example shown in FIG. 10, the taper angle of the taper surface 117 is increased or the insertion hole 15a of the seal member 15 is formed. By expanding the diameter,
It is conceivable to expand the seal portion 150 in the radial direction. However, in this case, the capillary phenomenon is impaired, the retaining force for the lubricating fluid is reduced, and the sealing property deteriorates. In particular, in the high-speed rotation range, a high centrifugal force acts on the lubricating fluid, so that the sealing property is significantly deteriorated. Further, it is conceivable to thicken the seal member 15 in the axial direction in order to maintain the sealing property, but the device itself has to be enlarged in the axial direction, which is disadvantageous for compactness, particularly for thinning.

Therefore, the present invention has been made in view of the above problems, and in a sliding type bearing device, while maintaining the bearing performance, the area of the seal portion is expanded without impairing the sealability, and At the same time, the purpose is to reduce the thickness.

Another object of the present invention is to provide a motor capable of maintaining good motor performance without deteriorating the sealing performance of the bearing device and at the same time achieving a thin type, and a disk device using the same. Especially.

[0015]

To achieve the above object, a bearing device according to the present invention comprises a shaft member having a shaft portion,
A sleeve member is disposed opposite to the shaft portion with a minute gap, and a lubricating fluid filled in the minute gap is provided, and at least one end portion of the minute gap is expanded in the radial direction with respect to the shaft portion. A bearing device that forms a seal portion that allows the interface fluctuation of the lubricating fluid and that rotatably supports the sleeve member and the shaft member,
The seal portion is composed of a plurality of divided regions in a radial direction with respect to the shaft portion, and each of the divided regions has a shape in which a capillarity phenomenon is generated to retain the lubricating fluid present therein and mutually It is characterized by communication.

A shaft member having a shaft portion, and a sleeve member arranged to face the shaft portion with a minute gap therebetween.
A lubricating fluid filled in the minute gap, and a seal member having an insertion hole through which the shaft portion is inserted and being in close contact with at least one end surface of the sleeve member, the inner peripheral surface of the insertion hole and the shaft portion. A gap between the sleeve member and the shaft member is made larger than the minute gap in the radial direction with respect to the shaft portion to form a seal portion that allows the interface fluctuation of the lubricating fluid, and the sleeve member and the shaft member are relatively rotatable. In the bearing device to support,
The seal portion is composed of a plurality of divided regions in a radial direction with respect to the shaft portion, and each of the divided regions has a shape in which a capillarity phenomenon is generated to retain the lubricating fluid present therein and mutually It is characterized by communication.

Here, the seal member mainly retains and replenishes the lubricating fluid in the minute gaps at all times, and prevents the careless entrainment of air into the lubricating fluid and the inadvertent evaporation of the lubricating fluid. Plays a role in isolating one end surface of the air from the atmosphere. Further, the fact that the divided regions are in communication with each other includes not only the case where they are communicated directly but also the case where they are communicated indirectly through a minute gap.

For example, considering the ease of manufacturing the divided regions, each of the divided regions is preferably formed by an annular member arranged coaxially with the shaft portion. Further, in order to more surely generate a capillary phenomenon in each of the divided regions, each of the divided regions may have a tapered shape that expands outward in the axial direction with respect to the shaft portion.

For the purpose of surely maintaining a sufficient filling state of the lubricating fluid in the minute gap, the sleeve member is preferably made of a porous sintered body. Further, from the viewpoint of providing smoother and stable high-precision rotation operation in a high-speed rotation range, a fluid dynamic pressure is applied to the lubricating fluid so that the shaft portion and the sleeve member are supported in a non-contact manner in the minute gap. It is preferable to generate and support the sleeve member and the shaft member so as to be rotatable relative to each other.
The fluid dynamic pressure is generated by providing a radial dynamic pressure generating groove for supporting a radial load on at least one of the shaft portion and the inner peripheral surface of the sleeve member facing the shaft portion. Can be achieved.

A motor of the present invention that achieves the above object is characterized by including any of the bearing devices described above.

Further, the disk device according to the present invention for achieving the above object is a disk device in which a disk-shaped recording medium capable of recording information is mounted, and a housing and a spindle fixed inside the housing for rotating the recording medium. A disk device having a motor and information access means for writing or reading information at a required position on the recording medium, wherein the spindle motor is the motor.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The bearing device of the present invention will be described in detail below with reference to the drawings. First, the first embodiment will be described by taking a dynamic pressure type as an example. FIG. 1 is an enlarged sectional view of an essential part showing a bearing device of the first embodiment. The same members and parts as those of the conventional bearing device shown in FIGS. 9 and 10 are denoted by the same reference numerals, and the description of structures and functions common to those is omitted here, and only different structures and functions are described. . The same applies to the second to fifth embodiments described later.

As shown in FIG. 1, the seal member 15 has an insertion hole 15a having a diameter larger than that of the inner peripheral surface 12a of the sleeve member 12, and the shaft portion 111 is inserted through the insertion hole 15a. , The lower surface 15c of the sleeve member 12
Through the through hole 131 (not shown) in close contact with the upper end surface 12b of the
Is fixed to the inner surface of the. A taper surface 117 is formed on the shaft portion 111 facing the inner peripheral surface of the insertion hole 15a of the seal member 15 so as to gradually reduce the shaft portion outer diameter upward in the axial direction. The gap formed between the tapered surface 117 and the inner peripheral surface of the insertion hole 15a of the seal member 15 forms an annular seal portion 150 with respect to the shaft portion 111, and the shaft portion 111 is located in the seal portion 150. An annular member 17 having an inner peripheral surface 17a that is coaxial with the shaft portion 111 and is parallel to the shaft portion 111, and an outer peripheral surface 17b that is inclined so as to decrease in diameter axially upward is disposed. That is, the area of the seal portion 150 by the annular member 17 is an inner area 150a formed by the gap between the inner peripheral surface 17a and the tapered surface 117, and the outer peripheral surface 17b and the insertion hole 15.
An outer region 150b formed by a gap between the inner peripheral surface of a and
, Will be divided into concentric circles.

These inner region 150a and outer region 150
Both b communicate with the lower end surface 17c of the annular member 17 and the upper end surface 12b of the sleeve member 12 and are continuously connected to the upper end of the shaft gap X. The shaft portion gap X is filled with the lubricating fluid L, and the inner region 150a and the outer region 150b retain a part of the lubricating fluid L and the interfaces Lsa and Lsb, respectively. The inner region 150a and the outer region 150
Since each of b has a tapered shape so that the gap thereof expands upward in the axial direction, it is possible to effectively cause a capillary phenomenon and reliably hold the lubricating fluid L existing inside each. . In addition, the seal member 15
Since the upper end surface 12b of the sleeve member 12 can be isolated from the atmosphere by the above, the lubricating fluid is always retained and replenished mainly in the minute gap X, and careless entrainment of air into the lubricating fluid L and the lubricating fluid L It is possible to prevent careless evaporation.

By thus dividing the radially enlarged seal portion 150 into two regions, namely, the inner region 150a and the outer region 150b, in the same radial direction, the capillary phenomenon and the sealing property associated therewith occur. The volume of the seal portion 150 can be increased while suppressing adverse effects and without expanding in the axial direction. Therefore, the lubricating fluid L thermally expands / contracts due to the temperature change and its interface Ls
Even if a and Lsb change more than before (broken line in the figure), the enlarged seal portion 150 (the inner area 150a and the outer area 150b) allows this change and the lubricating fluid L in the shaft gap X is increased. The filling state of can be maintained.

Here, an example of the annular member 17 is shown in FIG.
It will be explained based on. FIG. 2 is an external perspective view showing an example of the annular member. In addition, in the figure, the same reference numerals are given to the portions having the same names as those in FIG. The annular member 17 is made of a metal plate material that is plastically deformable and is punched into a ring shape by press molding. At the lower end portion of the outer peripheral surface 17b, four protrusions 170 (FIG. No. 1) is provided. The annular member 17 is arranged in the seal portion 150 (see FIG. 1), but at this time, each projection 170 is inserted into the insertion hole 15a of the seal member 15 by light press fitting.
The annular member 17 is fixed to the seal member 15 at a predetermined distance from the upper end surface 12b of the sleeve member 12 while being pressed against the inner peripheral surface of the sleeve member 12.

Although the number of the protrusions 170 is four in FIG. 2, if the number of protrusions is three or more, the annular member 1 is lightly press-fitted.
7 can be fixed stably. Further, the protrusion 170 may be provided on the inner peripheral surface 17a side of the annular member 17, and in this case,
Each protrusion 170 is in pressure contact with the shaft portion 111 or the tapered surface 117, so that the annular member 17 is fixed to the shaft member 11.

Furthermore, the inner region 150a and the outer region 150
Although b is communicated with each other so that the lubricating fluid L goes back and forth, even if the lubricating fluid L in one region decreases, it is replenished from the other side, and the deterioration of the sealing property is suppressed. ing. In FIG. 1, the inner region 150a and the outer region 1
Since the gap formed between the lower end surface 17c of the annular member 17 and the upper end surface 12b of the sleeve member 12 is utilized as a communication path for communicating the 50b, the lower end surface 17c and the upper end surface 12b are in a non-contact state. Is designed to keep
Not limited to this, for example, a notch is provided in the lower end surface 17c of the annular member 17, and then the lower end surface 17c is brought into contact with the upper end surface 12b of the sleeve member 12, and the notch portion is used as the communication passage. It is also possible to do so. Further, the material of the annular member 17 is not particularly limited, and may be made of a resin molded by a mold.

Further, as the sleeve member 12, a porous sintered body having continuous holes inside and capable of holding the lubricating fluid L, for example, Fe-Cu, Cu-Sn, Cu-Sn-P.
b, Fe-C, etc., various metal powders, metal compound powders, non-metal powders that are molded and sintered as raw materials, or even metal ones that do not have continuous holes inside are applied. I do not care. The former has the advantage of increasing the certainty with respect to maintaining the filled state of the lubricating fluid L in the shaft gap X, while it is assumed that the amount of interfacial fluctuation of the lubricating fluid L will increase, so the volume of the seal portion 150 Is particularly suitable for the bearing device of the present invention capable of expanding On the other hand, the latter is excellent in wear resistance due to contact with the shaft member 11, so that the dynamic pressure generating groove 12 provided on the inner peripheral surface 12 a of the sleeve member 12 is used.
The shapes of 1a and 121b can be maintained for a long time, which is effective when the bearing device is used for a long time.

Next, a second embodiment will be described with reference to FIG. FIG. 3 is an enlarged cross-sectional view of an essential part showing the bearing device of the second embodiment. The feature of the second embodiment is that the annular member 17
This is in consideration of the ease of manufacturing, and as shown in FIG.
The inner peripheral surface 17a and the outer peripheral surface 17b of the annular member 17 are both parallel to the shaft portion 111. On the other hand, the inner peripheral surface of the insertion hole 15a of the seal member 15 is inclined so as to expand in the axial direction upward.

Next, a third embodiment and a fourth embodiment will be described with reference to FIGS. 4 and 5. 4, 5
[Fig. 4] is an enlarged sectional view of an essential part showing a bearing device of a third embodiment and a bearing device of a fourth embodiment, respectively. The characteristics of the third and fourth embodiments are that the ease of manufacturing the shaft member 11 and the securing of the shaft strength are taken into consideration. As shown in FIGS. Such a tapered surface 117 is not formed, and the shaft portions 111 have the same shaft diameter. On the other hand, the inner peripheral surface 17a of the annular member 17 is inclined so as to expand in the axially upward direction. It is desirable that the surface of the shaft portion 111 that forms the shaft portion gap X is a highly accurate surface in order to reduce the sliding friction resistance, and if the tapered surface 117 is not provided as in the third and fourth embodiments, that highly accurate surface is achieved. The surface can be easily processed.

Further, in the third embodiment, as shown in FIG. 4, the outer peripheral surface 17b of the annular member 17 is parallel to the shaft portion 111, and the inner peripheral surface of the insertion hole 15a of the seal member 15 is It is inclined so as to expand its diameter upward in the axial direction. On the other hand, in the fourth embodiment, as shown in FIG. 5, the outer peripheral surface 17b of the annular member 17 is inclined so as to reduce its diameter upward in the axial direction, and the inner peripheral surface of the insertion hole 15a of the seal member 15 is It is parallel to the shaft 111.

Next, a fifth embodiment will be described with reference to FIG. FIG. 6 is an enlarged cross-sectional view of essential parts showing the bearing device of the fifth embodiment. The feature of the fifth embodiment is that the seal member 15 used in the first to fourth embodiments is eliminated to reduce the number of parts, and as shown in FIG.
The upper end of the inner peripheral surface 12a of the second member 2 is inclined so as to expand in the axially upward direction. Thereby, the sleeve member 1
A seal portion 150 is formed on the upper end of the shaft portion gap X by itself, and the annular member 17 is arranged in the seal portion 150.
An inner region 150a and an outer region 150b that communicate with each other are formed. The fifth embodiment is the sleeve member 1.
2 is effective when a metal made of metal that does not hinder the contact of the upper end surface 12b with the atmosphere is applied. The seal portion 150 (the inner region 150a and the outer region 150
Regarding the shapes of the shaft member 11, the annular member 17, and the sleeve member 12 that form b), in FIG. 6, the seal member 15 of the second embodiment shown in FIG.
And is not limited to this, the first,
Of course, it is possible to replace them as in the third and fourth embodiments. In addition, regarding the mode and attachment method of the annular member 17, similarly, the annular member 17 may be press-contacted and fixed to the shaft member 11 or the sleeve member 12.

As described above, the bearing device according to the present invention is capable of expanding the volume of the seal portion 150 without impairing the bearing performance and the sealing property and without expanding in the axial direction. Is preferred.

The bearing device of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the region of the seal portion 150 may be divided into three or more regions, and this can be achieved by arranging the plurality of annular members 17 concentrically.

Further, in the present embodiment, the dynamic pressure type bearing device is exemplified, but the effect is most remarkable when the seal portion 150 of the present invention is applied to the dynamic pressure type bearing device. . This is because in this dynamic pressure type bearing device, the sleeve member 12 is filled with a large amount of the lubricating fluid L in order to generate the fluid dynamic pressure, and the interface fluctuation amount is large as described above. Therefore, even in the dynamic pressure type bearing device, particularly in the full-fill structure in which the sleeve member 12 is made of the porous sintered body, the lubricating fluid L is more filled, and the effect becomes more remarkable. In connection with this, the present invention is also applicable to a dynamic pressure type bearing device having a partial fill structure in which the lubricating fluid is retained only in the main part of the bearing in the minute gap between the shaft member and the sleeve member. Further, as the other bearing device, a bearing device in which the lubricating fluid is used not for the dynamic pressure of the fluid but for reducing the sliding frictional resistance in the contact region is also applicable. Further, in the present embodiment, it is suitable mainly for supporting a radial load, but the present invention is not limited to this, and can be applied to a structure in which the shaft portion gap is configured to support a thrust load.

Finally, a motor according to the present invention and a disk device using this motor will be described. A major feature of the motor of the present invention and the disk device using this motor is that the bearing device described above is mounted. Hereinafter, a motor of the present invention and a disk device using the motor will be described in detail with reference to the drawings.

FIG. 7 is a vertical sectional view of an HDD spindle motor 72 equipped with a dynamic pressure type bearing device having a full-fill structure. The bracket 2 includes a base portion 21 provided at the center, a peripheral wall 22 provided in the outer peripheral direction of the base portion 21, and a flange portion 23 extending further outward from the peripheral wall 22, and these are integrally and It is formed coaxially.

An annular protrusion 24 is formed in the center of the base portion 21, and the dynamic pressure type bearing device 1 equipped with any of the bearing devices described above is fitted and fixed thereto. In addition, the aspect of FIG. 1 is shown for convenience in the figure. The upper end of the shaft member 11 of the bearing device 1 is fitted and fixed in a hole 31 formed in the center of the upper surface of the substantially cylindrical rotor hub 3. On the inner peripheral surface of the rotor hub 3, a cylindrical rotor magnet 32 magnetized in the circumferential direction with multiple poles is arranged.
Further, the stator 4 is arranged radially inward of the rotor magnet 32 so as to face the rotor magnet 32, and an annular protrusion 24 formed on the base portion 22 of the bracket 2.

A collar portion 33 is formed on the lower side of the outer circumference of the rotor hub 3, and a hard disk (not shown) is mounted on the collar portion 33. Specifically, after positioning the outer peripheral portion 34 of the rotor hub 3 and mounting a plurality of hard disks on the collar portion 33, a hole 35 is formed by a clamp member (not shown) or the like.
The hard disk is held and fixed to the rotor hub 3 by screwing.

Next, a disk device 70 using the spindle motor 72 will be described. FIG. 8 is a vertical cross-sectional view schematically showing the internal structure of a general disk device. Housing 71 that constitutes the outer shape of the disk device 70
A clean space in which dust and the like are extremely small is formed inside, and a spindle motor 72 mounted with a disc-shaped disk plate 73 for recording information is installed inside thereof. In addition, inside the housing 71, a head moving mechanism 7 for reading / writing information from / to the disk plate 73 is provided.
7, a head moving mechanism 77 is provided with a head 76 for reading and writing information on the disk plate 73, and the head 7
6, an arm 75 for supporting the head 6, a head 76, and an actuator section 74 for moving the arm 75 to a desired position on the disk plate 73. By using the spindle motor 72 shown in FIG. 7 as the spindle motor 72 of the disk device 70, it is possible to reduce the thickness and cost of the disk device while obtaining a desired rotation accuracy.

The motor of the present invention is also suitable for a cooling fan motor used for cooling electronic components such as a CPU.

[0043]

As described above, according to the bearing device of the present invention, the shaft member having the shaft portion, the sleeve member opposed to the shaft portion with a minute gap, and the minute gap filled with the sleeve member. And a lubricating fluid, wherein at least one end portion of the minute gap is enlarged in the radial direction with respect to the shaft portion,
Forming a seal portion that allows the interface fluctuation of the lubricating fluid,
In the bearing device that rotatably supports the sleeve member and the shaft member, the seal portion includes a plurality of divided regions in a radial direction with respect to the shaft portion, and each of the divided regions has a divided region. Since they have a shape that causes a capillary phenomenon to hold the lubricating fluid existing inside and communicate with each other, in a sliding type bearing device, even if there is a large interfacial fluctuation of the lubricating fluid in a minute gap, the bearing performance is improved. It is possible to expand the region of the flow path that will be the seal portion without impairing the sealing property while maintaining the same, and at the same time, achieve thinning.

Further, a shaft member having a shaft portion, and a sleeve member arranged facing the shaft portion with a minute gap,
A lubricating fluid filled in the minute gap, and a seal member having an insertion hole through which the shaft portion is inserted and being in close contact with at least one end surface of the sleeve member, the inner peripheral surface of the insertion hole and the shaft portion. A gap between the sleeve member and the shaft member is made larger than the minute gap in the radial direction with respect to the shaft portion to form a seal portion that allows the interface fluctuation of the lubricating fluid, and the sleeve member and the shaft member are relatively rotatable. In the bearing device to support,
The seal portion is composed of a plurality of divided regions in a radial direction with respect to the shaft portion, and each of the divided regions has a shape in which a capillarity phenomenon is generated to retain the lubricating fluid present therein and mutually When in communication, the above effect can be achieved by using the seal member, and the degree of freedom in the shape of the sleeve member can be increased.

If each of the divided areas is formed by an annular member arranged coaxially with the shaft portion, the divided areas can be easily obtained.
Further, when each of the divided regions has a tapered shape that expands outward in the axial direction with respect to the shaft portion, the capillary phenomenon can be more reliably generated in each of the divided regions.

If the sleeve member is made of a porous sintered body, the reliability of the filling state of the lubricating fluid in the minute gap increases. Further, when the dynamic pressure of the lubricating fluid is generated to support the sleeve member and the shaft member in a relatively rotatable manner, the shaft portion and the sleeve member are separated from each other by the minute gap. Since it is supported in a non-contact manner, it is possible to provide smoother and more stable rotation operation in the high-speed rotation range.

Since the motor according to the present invention is equipped with any one of the bearing devices described above, even if the interfacial fluctuation of the lubricating fluid in the minute gap is large, the sealing performance of the bearing device does not deteriorate. The performance can be maintained well, and at the same time thinning can be achieved.

Further, since the disk device according to the present invention is provided with the above-mentioned motor, the motor device has good motor performance and is thin, so that the disk device also has good read / write performance and can be made thin.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of an essential part showing a bearing device according to a first embodiment of the present invention.

FIG. 2 is an external perspective view showing an example of an annular member.

FIG. 3 is an enlarged sectional view of an essential part showing a bearing device according to a second embodiment of the present invention.

FIG. 4 is an enlarged sectional view of an essential part showing a bearing device according to a third embodiment of the present invention.

FIG. 5 is an enlarged sectional view of an essential part showing a bearing device according to a fourth embodiment of the present invention.

FIG. 6 is an enlarged sectional view of an essential part showing a bearing device according to a fifth embodiment of the present invention.

FIG. 7 is a sectional view showing an example of a motor according to the present invention.

FIG. 8 is a sectional view schematically showing an example of a disk device according to the present invention.

FIG. 9 is a cross-sectional view showing a conventional dynamic pressure type bearing device.

FIG. 10 is an enlarged cross-sectional view of a main part of the bearing device of FIG.

[Explanation of symbols]

1 Dynamic pressure bearing device 2 bracket 3 rotor hub 4 stator 11 Shaft member 12 Sleeve member 13 Sleeve support member 14 Thrust bush member 15 Seal member 17 Annular member 70 disk unit 71 housing 72 Spindle motor 73 Disc board 77 Head moving mechanism 111 Shaft 112 Thrust plate part 121a, 121b Radial dynamic pressure generating groove 121c, 141 thrust dynamic pressure generating groove 150 seal 150a, 150b divided areas 170 protrusion L Lubricating fluid Ls, Lsa, Lsb Lubricating fluid interface

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3J011 AA07 AA12 BA04 CA02 DA01                       JA02 KA02 KA03 LA01 MA21                       SB19                 5H605 BB05 BB14 BB19 CC04 EB06                       EB10 EB28                 5H607 AA00 BB01 BB09 BB14 BB17                       BB25 CC01 GG01 GG12 GG15                       JJ09

Claims (8)

[Claims] 1. A shaft member having a shaft portion, a sleeve member arranged to face the shaft portion with a minute gap therebetween, and a lubricating fluid filled in the minute gap, wherein at least the minute gap is provided. In a bearing device, one end portion of which is enlarged in a radial direction with respect to the shaft portion to form a seal portion which allows an interface fluctuation of the lubricating fluid, and which rotatably supports the sleeve member and the shaft member, The seal portion is composed of a plurality of divided regions in a radial direction with respect to the shaft portion, and each of the divided regions has a shape in which a capillarity phenomenon is generated to retain the lubricating fluid present therein and mutually A bearing device characterized by being communicated. 2. A shaft member having a shaft portion, a sleeve member arranged to face the shaft portion with a minute gap, a lubricating fluid filled in the minute gap, and an insertion member for inserting the shaft portion. A seal member having a hole and closely contacted to at least one end surface of the sleeve member, and a gap between the inner peripheral surface of the insertion hole and the shaft portion is larger than the minute gap in the radial direction with respect to the shaft portion. In the bearing device that forms a seal portion that allows the interface fluctuation of the lubricating fluid and rotatably supports the sleeve member and the shaft member, a plurality of seal portions are provided in the radial direction with respect to the shaft portion. The bearing device is characterized in that the divided regions are divided into a plurality of regions, and each of the divided regions has a shape in which a capillarity phenomenon occurs so as to retain the lubricating fluid present therein and communicates with each other. 3. The bearing device according to claim 1, wherein each of the divided areas is formed by an annular member arranged coaxially with the shaft portion. 4. The bearing device according to claim 1, wherein each of the divided regions has a tapered shape that expands outward in the axial direction with respect to the shaft portion. 5. The bearing device according to claim 1, wherein the sleeve member is made of a porous sintered body. 6. The bearing according to claim 1, wherein a fluid dynamic pressure is generated in the lubricating fluid to rotatably support the sleeve member and the shaft member. apparatus. 7. A motor comprising the bearing device according to any one of claims 1 to 6. 8. A disk device in which a disk-shaped recording medium capable of recording information is mounted, a housing, a spindle motor fixed inside the housing to rotate the recording medium, and information at a required position of the recording medium. A disk device having an information access unit for writing or reading data, wherein the spindle motor is the motor according to claim 7.