JP2021175905A - Fluid dynamic pressure bearing device, spindle motor and hard disc drive device - Google Patents

Abstract

To provide a fluid dynamic pressure bearing device which suppresses discharge of an out gas generated from an adhesive agent to the outside.SOLUTION: A fluid dynamic pressure bearing device includes: a base part 101 including a shaft 102; a rotor 110 supported so as to rotate relatively with respect to the base part 101; a dynamic pressure bearing part 215 formed by an outer peripheral surface of the shaft 102 and an inner peripheral surface of the rotor 110 opposed to the shaft 102; a lubrication oil C filled in the dynamic pressure bearing part 215; and a cap 160 which is fitted in an annular protrusion part 150 provided at the rotor 110. The cap 160 includes a flat plate part 161, and a cylindrical part 162 extending axially downward from an edge part of the flat plate part 161. Between the outer peripheral surface of the annular protrusion part 150 and an inner peripheral surface of the cylindrical part 162 of the cap 160, a fitting region 164 is provided. Between the cylindrical part 162 of the cap 160 and the rotor 110, a closed space 170 adjacent to the fitting region 164 is provided across the whole periphery, and a sealing material is held in the closed space.SELECTED DRAWING: Figure 4

Description

The present invention relates to a fluid dynamic bearing device, a spindle motor, and a hard disk drive device, and more particularly to a technique for suppressing the release of outgas generated from an adhesive for fixing a cap for preventing leakage of lubricating oil.

The fluid dynamic bearing device of the spindle motor that rotates the recording disk of the hard disk drive device is a device that generates dynamic pressure in the lubricating oil interposed between the shaft fixed to the fixed part and the sleeve part of the rotating member. be. In order to prevent this lubricating oil from leaking to the outside from between the shaft and the sleeve portion, a cap is fixed to the sleeve portion to cover the liquid level of the lubricating oil from above in the axial direction (for example, patented). Document 1).

FIG. 9 is a cross-sectional view showing a main part of the conventional spindle motor 1. The spindle motor 1 shown in this figure is roughly configured by fixing a shaft 2 to a fixed portion (not shown) and supporting a rotor 3 on the shaft 2 so as to be relatively rotatable by a fluid dynamic bearing 4. In the hydrodynamic bearing 4, the conical bearing member 5 is fixed to the shaft 2, and the conical bearing surface 5a and the outer peripheral surface 2a of the shaft 2 provided in the lower half of the conical bearing member 5 and the rotor side conical surface 3a of the rotor 3 The dynamic bearing portion 6 formed by the inner peripheral surface 3b and the inner peripheral surface 3b is filled with lubricating oil 7.

Here, an annular convex portion 3c protruding in the axial direction is formed on the end surface of the rotor 3, and a cap 8 is fitted to the annular convex portion 3c to cover the liquid level of the lubricating oil 7 from above in the axial direction. It prevents the lubricating oil 7 from leaking. The cap 8 is composed of a flat plate portion 8a and a cylindrical portion 8b extending axially downward from the edge portion of the flat plate portion 8a, and when the cap 8 is fixed with an adhesive, the annular convex portion 3c coated with the adhesive. The inner peripheral surface of the cylindrical portion 8b of the cap 8 is fitted into the outer peripheral surface of the cap 8 so as to be in a press-fitted state to fix the cap 8. The adhesive is applied to the entire circumference for the purpose of preventing leakage of the lubricating oil 7. At this time, the adhesive is exposed to the outside so as to be scraped off by the lower end of the cylindrical portion 8b of the cap 8 to form an adhesive pool 9. When outgas is generated from the exposed adhesive pool 9, the outgas released to the outside of the spindle motor 1 lowers the cleanliness around the disc, and in some cases, a read / write error of the disc may occur.

Japanese Unexamined Patent Publication No. 2012-89200

Therefore, an object of the present invention is to provide a fluid dynamic bearing device, a spindle motor, and a hard disk drive device capable of suppressing the release of outgas generated from a sealing material such as an adhesive to the outside.

The present invention includes a fixed portion provided with a shaft, a rotating portion rotatably supported relative to the fixed portion, an outer peripheral surface of the shaft, and an inner peripheral surface of the rotating portion facing the shaft. In a fluid dynamic bearing device provided with a dynamic bearing portion formed of, a lubricating oil filled in the dynamic bearing portion, and a cap fitted to an annular convex portion provided in the rotating portion. The cap includes a flat plate portion and a cylindrical portion extending downward in the axial direction from the edge portion of the flat plate portion, and is fitted between the outer peripheral surface of the annular convex portion and the inner peripheral surface of the cylindrical portion of the cap portion. A region is provided, and a closed space adjacent to the fitting region is provided between the cylindrical portion and the rotating portion of the cap over the entire circumference, and the sealing material is held in the closed space. It is a pressure bearing device.

According to the present invention, since the sealing material exposed from the fitting region between the outer circumference of the annular convex portion and the inner circumference of the cylindrical portion of the cap is sealed in the closed space, the generated outgas is sealed in the closed space. Therefore, the release of the spindle motor to the outside is suppressed.

The closed space can be provided between the inner peripheral surface of the cylindrical portion of the cap and the outer peripheral surface of the annular convex portion. In this case, the closed space can be formed by forming a groove on the outer peripheral surface of the annular convex portion or by forming a groove on the inner peripheral surface of the cylindrical portion of the cap. Alternatively, grooves can be formed in both the annular convex portion and the cylindrical portion. In any case, it is preferable to provide the closed space with a tapered portion adjacent to the fitting region and whose radial dimension decreases toward the fitting region side. With such a configuration, the liquid sealing material exposed from the fitting region is held on the fitting region side by the capillary force, and leakage of the sealing material from the closed space to the outside is suppressed.

A flange portion that projects outward in the radial direction can be provided at the end of the cylindrical portion of the cap. In this case, by bringing the flange portion into contact with the axial end face of the rotating portion, the flange portion comes into contact with the axial end face of the rotating portion over a wide area, and leakage of outgas generated in the closed space is effectively suppressed. be able to.

An annular groove may be provided on the axial end surface of the rotating portion, and the outer peripheral surface of the cylindrical portion of the cap may be brought into contact with the inner peripheral surface of the annular groove. In this case, by providing a gap between the bottom surface of the annular groove and the end surface of the cylindrical portion of the cap, the gap can be used as a closed space. Such a closed space can be formed in combination with the closed space.

A second closed space can be formed over the entire circumference at a position axially separated from the closed space. With such a configuration, even if the sealing material leaks from the closed space, it is sealed in the second closed space. Further, even if the outgas generated from the sealing material leaks from the closed space, it is sealed in the second closed space.

The present invention is a spindle motor provided with a fluid dynamic bearing device having the above configuration, and is a hard disk drive device provided with the spindle motor.

According to the present invention, there are provided a fluid dynamic bearing device, a spindle motor, and a hard disk drive device capable of suppressing the release of outgas generated from a sealing material such as an adhesive to the outside.

It is a perspective view which shows the hard disk drive device of 1st Embodiment of this invention. It is sectional drawing which shows the hard disk drive apparatus of 1st Embodiment of this invention. It is sectional drawing which shows the spindle motor of 1st Embodiment of this invention. (A) is an enlarged cross-sectional view of a main part of the spindle motor according to the first embodiment of the present invention, and (B) is an enlarged view of the part indicated by the arrow B of (A). (A) is an enlarged cross-sectional view of a main part of the spindle motor according to the second embodiment of the present invention, and (B) is an enlarged view of the part indicated by the arrow B of (A). (A) is an enlarged cross-sectional view of a main part of the spindle motor according to the third embodiment of the present invention, and (B) is an enlarged view of the part indicated by the arrow B of (A). (A) is an enlarged cross-sectional view of a main part of the spindle motor according to the fourth embodiment of the present invention, and (B) is an enlarged view of the part indicated by the arrow B of (A). (A) is an enlarged cross-sectional view of a main part of the spindle motor according to the fifth embodiment of the present invention, (B) is an enlarged view of the part indicated by the arrow B of (A), and (C) is a modified example of (B). It is an enlarged view which shows. It is an enlarged cross-sectional view of the main part of the conventional spindle motor.

1. 1. First Embodiment (Hard Disk Driver)
FIG. 1 is a perspective view showing an overall configuration of a hard disk drive device 10 using a spindle motor according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view cut along a plane including a rotation axis. As shown in these figures, the hard disk drive device 10 includes a spindle motor 100 and a plurality of hard disks 13 that are attached to the spindle motor 100 and rotate. Further, the hard disk drive device 10 includes a swing arm 11 that supports a plurality of magnetic heads 12 facing the hard disk 13, an actuator 14 that drives the swing arm 11, and a control unit 15 that controls these devices. There is.

(Spindle motor)
FIG. 3 is a cross-sectional view of the spindle motor 100 of the first embodiment cut along a surface including a rotation shaft. The fixing portion of the spindle motor 100 includes a base portion 101 and a shaft 102 fixed to the base portion 101, and conical bearing members 201 and 301 are fixed to the shaft 102. Further, a cylindrical portion 101a extending upward in the axial direction of the shaft 102 is formed on the base portion 101, and a stator core 103 is fixed to the outer periphery of the cylindrical portion 101a. The stator core 103 is formed by laminating a plurality of thin plate-shaped soft magnetic materials (for example, electromagnetic steel plates) having a ring shape in the axial direction, and includes a plurality of polar teeth protruding outward in the radial direction. The plurality of polar teeth are provided at equal intervals along the circumferential direction, and a coil 104 is wound around each of them.

The rotating part of the spindle motor 100 includes a rotor 110. The rotor 110 has an outer cylindrical portion 111 and an inner cylindrical portion 112 fixed to the inside of the outer cylindrical portion 111, and an annular rotor magnet 113 is fixed to the inner peripheral surface side of the outer cylindrical portion 111. The rotor magnet 113 is magnetized so that portions adjacent to the SNSN ... Alternately have different polarities along the circumferential direction. The inner circumference of the rotor magnet 113 faces the outer circumference of the polar teeth of the stator core 103 with a gap. Then, by supplying a driving current to the coil 104, a driving force for rotating the rotor magnet 113 is generated, and the rotor 110 rotates with respect to the shaft 102 and the base portion 101 about the shaft 102. This principle is similar to that of a normal spindle motor.

A flange portion 114 extending outward in the radial direction is formed on the peripheral edge of the lower end portion of the outer cylindrical portion 111. The flange portion 114 functions as a disk mounting portion for stacking and mounting a plurality of hard disks 13. As shown in FIG. 3, the hard disk 13 is placed on the flange portion 114, and the hard disks 13 are stacked one after another on the hard disk 13 via the spacer 16, and a total of nine hard disks 13 are stacked. The uppermost hard disk 13 is fixed to the rotor 110 by a clamp 18 attached to the upper surface of the rotor 110 with screws 17.

(Fluid dynamic bearing device)
The rotor 110 is rotatably supported by the fluid dynamic bearings 200 and 300 relative to the shaft 102. The fluid dynamic bearing 200 includes a conical bearing member 201 fixed to the shaft 102, and the fluid dynamic bearing 300 includes a conical bearing member 301 fixed to the shaft 102. In the following description, the fluid dynamic pressure bearing 200 will be described as an example with reference to FIG. FIG. 4 shows an enlarged state of the fluid dynamic pressure bearing 200.

A through hole 209 extending in the axial direction is formed in the center of the conical bearing member 201, and the shaft 102 is press-fitted into the through hole 209 to connect the conical bearing member 201 and the shaft 102. The conical bearing member 201 and the shaft 102 may be bonded by an adhesive or laser welding.

The conical bearing member 201 has a lower conical bearing surface 202 and an upper sealed conical surface 203 as radial outer surfaces. The conical bearing surface 202 faces each other with the rotor-side conical surface 115 provided on the inner peripheral surface of the rotor 110 via a minute gap 211. A dynamic pressure groove is formed on at least one of the conical bearing surface 202 and the rotor-side conical surface 115.

A tapered seal portion 212 is provided between the seal conical surface 203 and the inner peripheral surface of the rotor 110. The taper seal portion 212 is formed over the entire circumference along the circumferential direction, and as shown in FIG. 4A, has a tapered shape such that the size of the gap gradually increases from the lower side to the upper side in the axial direction. The liquid level is formed on the taper seal portion 212, and the leakage of the lubricating oil C is prevented by the capillary force.

A gap 210, which is an annular space, is provided between the lower end of the inner peripheral surface of the conical bearing member 201 and the outer peripheral surface of the shaft 102, and the gap 210 and the tapered seal portion 212 communicate with each other by a circulation hole 205. ing. Two circulation holes 205 are provided at equal intervals in the circumferential direction when viewed from the axial direction. The gap 210 and the above-mentioned gap 211 communicate with each other, and they also communicate with the gap 213 between the inner peripheral surface 112a of the inner cylindrical portion 112 and the outer peripheral surface 102a of the shaft 102. As a result, the taper seal portion 212, the circulation hole 205, and the gaps 210, 211, 213 are connected in a state in which the lubricating oil C can move. Then, the dynamic pressure bearing portion 215 formed by the gap 211 and the gap 213 is filled with the lubricating oil C to form the fluid dynamic pressure bearing 200.

(Cap mounting structure)
An annular convex portion 150 projecting upward in the axial direction is formed on the upper end surface of the inner cylindrical portion 112 over the entire circumference. As shown in FIG. 4 (B), on the outer peripheral surface of the annular convex portion 150, a large diameter portion 151 on the upper end side and a small diameter portion 152 on the lower end side having a diameter smaller than that of the large diameter portion 151 cover the entire circumference. A tapered portion 153 is formed between the large diameter portion 151 and the small diameter portion 152 so that the size of the gap gradually decreases from the lower side to the upper side in the axial direction over the entire circumference. A taper seal portion 153a is formed between the taper portion 153 and the inner peripheral surface 162a of the cylindrical portion 162 of the cap 160. A cap 160 is fixed to such an annular convex portion 150.

The cap 160 covers the liquid level of the lubricating oil C existing in the taper seal portion 212 from above to prevent the lubricating oil C from leaking. The cap 160 is composed of an annular flat plate portion 161 and a cylindrical portion 162 extending downward from the edge portion of the flat plate portion 161, and has a hole 163 in the center through which the shaft 102 penetrates. The cap 160 is fitted into the annular convex portion 150 whose outer peripheral surface is coated with an adhesive as a sealing material so as to be press-fitted, and the lower end surface of the cylindrical portion 162 is in contact with the upper end surface of the inner cylindrical portion 112. I'm in contact. As a result, a closed space 170 is formed between the cap 160 and the annular convex portion 150. In addition, "fitting so as to be in a press-fitting state" refers to a state of tightening and fitting, and the means for setting the state of tightening and fitting is arbitrary such as press-fitting, shrink-fitting, and cold-fitting. Further, the cap 160 may be fitted to the annular convex portion 150 in a state of being fitted in a gap. In that case, the cap 160 and the annular protrusion 150 are fixed to each other only by the adhesive force of the adhesive.

When the cap 160 is press-fitted into the annular convex portion 150, most of the adhesive is press-fitted formed by the large diameter portion 151 of the annular convex portion 150 and the inner peripheral surface of the cylindrical portion 162 of the cap 160. It is scraped from the region (fitting region) 164 by the lower end of the cylindrical portion 162 to form an adhesive pool 171. The adhesive pool 171 is held in the closed space 170. A part of the adhesive may be held in the press-fitting region 164.

The liquid adhesive held in the closed space 170 stays on the press-fitting region 164 side by the capillary force of the tapered seal portion 153a formed between the tapered portion 153 of the annular convex portion 150 and the cylindrical portion 162 of the cap 160. For example, heat is applied to cure. As a result, the fixing of the cap 160 to the annular convex portion 150 is completed, and the leakage of the lubricant C of the taper seal portion 212 is prevented.

In the fluid dynamic bearing device having the above configuration, even if outgas is generated from the hardened adhesive pool 171, the adhesive pool 171 is sealed in the closed space 170, so that the outgas is sealed in the closed space. , Leakage of the spindle motor 100 to the outside is suppressed.

In particular, in the first embodiment, since the tapered seal portion 153a is formed between the tapered portion 153 of the annular convex portion 150 and the cylindrical portion 162 of the cap 160, leakage of the adhesive from the closed space 170 is effective. Is suppressed.

In the first embodiment, the annular convex portion 150 is provided with the tapered portion 153, but only the large diameter portion 151 and the small diameter portion 152 can be provided. Further, the cap 160 can also be provided with a large diameter portion, a small diameter portion, and a tapered portion, and only the cap 160 can be provided with a large diameter portion, a small diameter portion, and a tapered portion. Further, a resin other than the adhesive, natural rubber, or the like can be used as the sealing material.

The present invention is not limited to the fluid dynamic pressure bearings 200 and 300 using the conical bearing members 201 and 301 as described above, but is between the outer peripheral surface of the shaft 102 and the inner peripheral surface of the inner cylindrical portion 112. A dynamic bearing portion may be provided in the gap. In that case, a dynamic pressure groove is formed in at least one of the two. Further, a thrust bearing can be arranged on the lower end surface side of the inner cylindrical portion 112, and an axial dynamic pressure bearing portion can be provided between the two. In that case, a dynamic pressure groove is formed in at least one of the two.

2. Second Embodiment FIG. 5 is a diagram showing a second embodiment of the present invention. In this second embodiment, the configuration is the same as that of the first embodiment except that the flange portion 165 is formed at the lower end portion of the cylindrical portion 162 of the cap 160. Therefore, the components equivalent to those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. A flange portion 165 is formed at the lower end portion of the cylindrical portion 162 of the cap 160 by bending it at a right angle outward in the radial direction by, for example, press molding. The entire circumference of the flange portion 165 is brought into contact with the upper end surface of the inner cylindrical portion 112, whereby a closed space 170 is formed between the cap 160 and the annular convex portion 150.

In the second embodiment, not only the same operations and effects as those in the first embodiment can be obtained, but also the flange portion 165 comes into contact with the upper end surface of the inner cylindrical portion 112 over a wide area, so that the adhesive pool 171 is obtained. It is possible to effectively suppress the leakage of the outgas generated from the closed space 170 from the closed space 170. Further, even if the cap 160 is formed by press forming, it is not necessary to finish the flange portion 165, so that the manufacturing cost can be reduced.

3. 3. Third Embodiment FIG. 6 is a diagram showing a third embodiment of the present invention. This third embodiment is the same as the second embodiment except that the annular groove 154 is formed at a portion corresponding to the flange portion 165 of the cap 160 on the upper end surface of the inner cylindrical portion 112. Therefore, the components equivalent to those in the second embodiment are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 6B, an annular groove 154 is formed on the upper end surface of the inner cylindrical portion 112 over the entire circumference, and the annular groove 154 accommodates a part of the flange portion 165 of the cap 160. .. A tapered portion 154a that expands upward is formed on the inner peripheral edge portion on the outer side in the radial direction of the annular groove 154. By bringing the outer peripheral surface of the flange portion 165 into close contact with the inner peripheral surface 154b on the radial outer side of the annular groove 154, the space between the annular convex portion 150 and the cylindrical portion 162 of the cap 160, the bottom surface of the annular groove 154, and the flange A closed space 172 having an L-shaped cross section is formed by the space between the lower end surface and the lower end surface of the portion 165.

In the third embodiment, not only the same operations and effects as those in the first embodiment can be obtained, but also the closed space 172 has an L-shaped cross section and a large volume, and more outgas can be sealed. .. Further, since the tapered portion 154a is formed on the inner peripheral edge portion on the radial outer side of the annular groove 154, the cap 160 can be easily press-fitted into the annular convex portion 150.

4. Fourth Embodiment FIG. 7 is a diagram showing a fourth embodiment of the present invention. The fourth embodiment is the same as the third embodiment except that the outer peripheral surface of the annular convex portion 150 is formed from the cylindrical surface 150a having no small diameter portion. Therefore, the components equivalent to those in the third embodiment are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 7B, almost the entire inner peripheral surface of the cylindrical portion 162 of the cap 160 is in contact with the cylindrical surface 150a of the annular convex portion 150, and the bottom surface of the annular groove 154 and the flange portion 165 of the cap 160 are in contact with each other. A closed space 173 is formed between them. A bent R portion 165a formed by bending a material by press molding is formed at a corner portion on the inner peripheral side of the flange portion 165, and an adhesive pool 171 is formed in a closed space 173 including the bent R portion 165a. There is.

In this fourth embodiment, it goes without saying that the same operations and effects as those in the first embodiment can be obtained, and between the inner peripheral surface of the cylindrical portion 162 of the cap 160 and the cylindrical surface 150a of the annular convex portion 150. Since the area of the press-fitting region 164 is large, leakage of the lubricating oil C can be effectively suppressed. In particular, in the fourth embodiment, the space between the bent R portion 165a of the flange portion 165 and the cylindrical surface 150a of the annular convex portion 150 exerts the same function as the taper sealing portion 153a described above, so that the liquid adhesive is used. Is held on the press-fitting region 164 side of the closed space 173, and the leakage of the adhesive is effectively suppressed.

5. Fifth Embodiment FIG. 8 is a diagram showing a fifth embodiment of the present invention. In the fifth embodiment, the same components as those in the first to fourth embodiments are designated by the same reference numerals, and the description thereof will be omitted. As shown in FIG. 8B, the lower end surface of the cylindrical portion 162 of the cap 160 is separated from the upper end surface of the inner cylindrical portion 112. A peripheral groove 155 having a tapered portion 153 is formed on the cylindrical surface 150a of the annular convex portion 150. The space between the peripheral groove 155 and the cylindrical portion 162 of the cap 160 is a closed space 174 adjacent to the press-fitting region 164. Further, on the lower side of the peripheral groove 155, a second closed space 175 is formed in which the entire circumference of the cylindrical surface 150a is cut out in a V-shaped cross section.

In the fifth embodiment of the above configuration, the adhesive scraped from the press-fitting region 164 is sealed in the closed space 174, and the leakage of outgas from the adhesive pool 171 is suppressed, of course, and the adhesive is used. Even if the adhesive leaks from the closed space 174, the adhesive is sealed in the second closed space 175. Further, even when outgas is generated from the adhesive pool 171 and leaks from the closed space 174, it is sealed in the second closed space 175. Therefore, leakage of outgas to the outside of the spindle motor 100 can be effectively suppressed. In the present invention, the second closed space 175 is not always essential, and as shown in FIG. 8C, only the peripheral groove 155 can be formed on the cylindrical surface 150a.

6. Combination of Embodiments (1) The cylindrical portion 162 of the cap 160 of the fourth embodiment shown in FIG. 7 can be changed to the shape of the cylindrical portion 162 of the first embodiment shown in FIG. 4 without the flange portion 165.
(2) The closed space 174 and the second closed space 175 of the fifth embodiment shown in FIG. 8 can be formed on the cylindrical surface 150a of the annular convex portion 150 of the fourth embodiment shown in FIG. 7.
(3) The peripheral groove 155 and the second closed space 175 of the fifth embodiment shown in FIG. 8 can be formed on the outer peripheral surface of the annular convex portion 150 of the first to third embodiments.

The present invention can be applied to a fluid dynamic bearing device, a spindle motor, and a hard disk drive device, which are required to reduce harmful effects due to outgas generated from an adhesive.

10 ... hard disk drive, 11 ... swing arm, 12 ... magnetic head, 13 ... hard disk, 14 ... actuator, 15 ... control unit, 16 ... spacer, 17 ... screw, 18 ... clamp, 100 ... spindle motor, 101 ... base , 101a ... Cylindrical part, 102 ... Shaft, 102a ... Outer surface, 103 ... Stator core, 104 ... Coil, 110 ... Rotor, 111 ... Outer cylindrical part, 112 ... Inner cylindrical part, 112a ... Inner peripheral surface, 113 ... Rotor magnet, 114 ... Flange portion, 115 ... Rotor side conical surface, 150 ... Annular convex portion, 150a ... Cylindrical surface, 151 ... Large diameter portion, 152 ... Small diameter portion, 153 ... Tapered portion, 153a ... Tapered seal portion, 154 ... Circular groove, 154a ... Tapered part, 154b ... Inner peripheral surface, 155 ... Circumferential groove, 160 ... Cap, 161 ... Flat plate part, 162 ... Cylindrical part, 162a ... Inner peripheral surface, 163 ... Hole, 164 ... Press-fit area (fitting area), 165 ... Flange part, 165a ... Bending R part, 170 ... Closed space, 171 ... Adhesive pool, 172, 173, 174 ... Closed space, 175 ... Second closed space, 200 ... Fluid dynamic bearing, 201 ... Conical bearing Member, 202 ... Conical bearing surface, 203 ... Sealed conical surface, 205 ... Circulation hole, 209 ... Through hole, 210, 211,213 ... Gap, 212 ... Tapered seal part, 215 ... Dynamic pressure bearing part, C ... Lubricant.

Claims (9)

A fixed part with a shaft and
A rotating portion that is rotatably supported relative to the fixed portion,
A dynamic bearing portion formed by an outer peripheral surface of the shaft and an inner peripheral surface of the rotating portion facing the shaft, and a dynamic bearing portion.
Lubricating oil filled in the dynamic bearing portion and
A cap that fits into the annular convex portion provided on the rotating portion and
In a hydrodynamic bearing device equipped with
The cap includes a flat plate portion and a cylindrical portion extending downward in the axial direction from the edge portion of the flat plate portion.
A fitting region is provided between the outer peripheral surface of the annular convex portion and the inner peripheral surface of the cylindrical portion of the cap.
A fluid dynamic bearing device in which a closed space adjacent to the fitting region is provided between the cylindrical portion and the rotating portion of the cap over the entire circumference, and a sealing material is held in the closed space. The fluid dynamic bearing device according to claim 1, wherein the closed space is provided between an inner peripheral surface of the cylindrical portion of the cap and an outer peripheral surface of the annular convex portion. The fluid dynamic bearing device according to claim 2, wherein the cylindrical portion of the cap is in contact with an axial end surface of the rotating portion. The fluid dynamic bearing device according to claim 1 or 2, wherein an annular groove is provided on the axial end surface of the rotating portion, and the outer peripheral surface of the cylindrical portion of the cap is brought into contact with the inner peripheral surface of the annular groove. The fluid dynamic bearing device according to any one of claims 2 to 4, wherein the closed space is provided with a tapered portion adjacent to the fitting region and whose radial dimension becomes smaller toward the fitting region side. The fluid dynamic bearing device according to any one of claims 2 to 5, wherein a flange portion protruding outward in the radial direction is provided at an end portion of the cylindrical portion of the cap. The fluid dynamic bearing device according to any one of claims 2 to 6, wherein a second closed space is formed over the entire circumference at a position axially separated from the closed space. A spindle motor provided with the fluid dynamic bearing device according to any one of claims 1 to 7. A hard disk drive device including the spindle motor according to claim 8.

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