JP2014146393A - Disk driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disk driving device suppressing the evaporation and dispersion of a lubricant contained in a fluid dynamic bearing unit.SOLUTION: The disk driving device includes; a base; a hub fixed with a magnet; and a fluid dynamic bearing unit for generating a fluid dynamic pressure in a lubricant and rotatably supporting the hub. The hub includes a hub-opposing surface facing the base in an area located more on the outer side in a radial direction than an inner peripheral surface of the magnet. The base includes a base-opposing surface facing the hub-opposing surface via a facing gap. A gas-dynamic pressure generation groove for making a gas interposed in the facing gap generate a dynamic pressure in a direction of pump-in when the hub rotates with respect to the base is provided on either the hub-opposing surface or the base-opposing surface.

Description

  The present invention relates to a disk drive device including a fluid dynamic pressure bearing unit.

  Some disk drive devices such as hard disk drives are equipped with a fluid dynamic bearing unit capable of stable high-speed rotation. For example, in a motor including a hydrodynamic bearing described in Patent Document 1, a lubricant is filled between a sleeve that forms a part of a stator and a shaft that forms a part of a rotor, and is generated in the lubricant. The rotor is supported in a non-contact state by the dynamic pressure, and smooth high-speed rotation is realized.

JP 2008-275047 A JP 2011-150770 A

On the other hand, there is a demand for the disk drive device to further increase the recording capacity. One way to meet this requirement is to improve the recording density.
In order to improve the recording density, it is conceivable to reduce the gap between the recording / reproducing head and the disk surface. However, if this gap is small, the recording / reproducing head cannot accurately trace the tracks on the disk because only a small amount of particles adhere to the disk surface, resulting in a read / write failure. In the worst case, the recording / reproducing head is damaged, and the disk drive device malfunctions.

One cause of such particles is the vaporization of the lubricant contained in the fluid dynamic bearing unit due to the high-speed rotation of the disk, that is, the high-temperature environment accompanying the high-speed rotation of the motor. The vaporized lubricant diffuses in the disk drive device and may be condensed and deposited on the disk surface.
In addition, regarding the high temperature environment, the temperature of the operating atmosphere of the disk drive device is high even with downsizing, and there is a demand for enabling the use of the disk drive device even at a higher temperature, for example, an ambient temperature of 85 ° C. or higher. There is.
Furthermore, there is also a demand to increase the time until the lubricant is vaporized and consumed, and to ensure a long life of, for example, 5 years or longer.

Accordingly, the present invention has been made in view of the above circumstances, and is a disk drive that can further increase the recording capacity by suppressing the vaporization and diffusion of the lubricant contained in the fluid dynamic pressure bearing unit. An object is to provide an apparatus.
Another object of the present invention is to provide a disk drive device that can prevent vaporization of the lubricant contained in the fluid dynamic pressure bearing unit and obtain a long life.

  In order to achieve the above object, a disk drive device according to one aspect of the present invention includes a base, a hub having a disk mounting portion, and a ring-shaped magnet fixed to the inner peripheral surface, and fluid movement to the lubricant. A hydrodynamic bearing unit that rotatably supports the hub with respect to the base by generating pressure, and the hub faces the base in a region radially outward from the inner peripheral surface of the magnet. A hub-facing surface, wherein the base has a base-facing surface facing the hub-facing surface via a facing gap, and the hub is located on either the hub-facing surface or the base-facing surface with respect to the base. And a gas dynamic pressure generating groove for generating a dynamic pressure in the pump-in direction in the gas interposed in the facing gap when rotating.

  According to the present invention, there is provided a disk drive device capable of increasing the recording capacity. In addition, a disk drive device that provides a long life is provided.

1 is an exploded perspective view showing a disk drive device according to an embodiment of the present invention. It is the sectional view on the AA line of FIG. FIG. 3 is an enlarged cross-sectional view showing an enlarged periphery of a shaft body 6 and a bearing body 8 in FIG. 2. It is sectional drawing which shows the process of irradiating input light to a lubricant, and obtaining output light.

  The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent components and members shown in the drawings are denoted by the same reference numerals, and repeated descriptions are appropriately omitted. In addition, the dimensions of the members in each drawing are appropriately enlarged or reduced for easy understanding. Also, in the drawings, some of the members that are not important for describing the embodiment are omitted.

  The disk drive device according to the embodiment is preferably used as a disk drive device such as a hard disk drive that mounts a magnetic recording disk that magnetically records data and rotationally drives it. For example, the disk drive device includes a stationary body, a rotating body, and a fluid bearing that rotatably supports the rotating body with respect to the stationary body by generating fluid dynamic pressure in the lubricant. For example, the disk drive device includes a gas dynamic pressure generating groove that generates a fluid dynamic pressure in the gas when the rotating body rotates with respect to the stationary body. As an example, the gas dynamic pressure generating groove is provided on one of opposing surfaces where the rotating body and the stationary body face each other across the opposing gap, and generates fluid dynamic pressure in the gas interposed in the opposing gap. For example, the gas dynamic pressure generating groove can be provided so as to surround the fluid bearing. The rotator includes mounting means that can mount a driven medium such as a magnetic recording disk. Further, the disk drive device includes a rotation drive means for applying a rotation torque to the rotating body. This rotation driving means is, for example, a brushless spindle motor. This rotation driving means includes, for example, a coil and a magnet.

(Embodiment)
FIG. 1 is a perspective view showing a disk drive device 100 according to an embodiment. FIG. 1 shows a state in which the top cover 22 is separated for easy understanding of the invention. In FIG. 1, members that are not important for explanation, such as clampers and electronic circuits, are omitted. The disk drive device 100 includes a chassis 24, a shaft 110, a hub 26, a magnetic recording disk 62, a data read / write unit 60, a top cover 22, a central screw 74, and six peripheral screws 104, for example. ,including.
Hereinafter, the side on which the hub 26 is mounted with respect to the chassis 24 will be described as the upper side. A direction along the rotation axis R of the rotating body is referred to as an axial direction, an arbitrary direction passing through the rotation axis R on a plane perpendicular to the rotation axis R is referred to as a radial direction, and an arbitrary direction on the plane is referred to as a planar direction. Sometimes. The indication of the direction does not limit the posture in which the disk drive device 100 is used, and the disk drive device 100 can be used in an arbitrary posture.

  The magnetic recording disk 62 is, for example, a glass 2.5-inch magnetic recording disk having a diameter of 65 mm, and the diameter of the central hole is 20 mm. When the thickness of the magnetic recording disk 62 is reduced, the rigidity is lowered, and the processing flatness may be lowered due to warping during polishing when the disk drive device 100 is manufactured. On the other hand, increasing the thickness of the magnetic recording disk 62 may increase the weight. It has been found that the magnetic recording disk 62 has practicality in terms of rigidity and weight at least in the range of 0.5 mm to 1.25 mm. In the present embodiment, the thickness of the magnetic recording disk 62 is set to 0.7 mm to 0.9 mm, and a decrease in processing flatness is suppressed to prevent a decrease in recording density. For example, four magnetic recording disks 62 are mounted on the hub 26 and rotate as the hub 26 rotates. As will be described later, the magnetic recording disk 62 is fixed to the hub 26 by a spacer 72 and a clamper 78.

  The chassis 24 includes a bottom plate portion 24A that forms the bottom portion of the disk drive device 100, and an outer peripheral wall portion 24B that is formed along the outer periphery of the bottom plate portion 24A so as to surround the mounting area of the magnetic recording disk 62. For example, six screw holes 24C are provided on the upper surface of the outer peripheral wall portion 24B. The chassis is sometimes referred to as the base.

  The data read / write unit 60 includes a recording / reproducing head (not shown), a swing arm 64, a voice coil motor 66, and a pivot assembly 68. The recording / reproducing head is attached to the tip of the swing arm 64 and records data on the magnetic recording disk 62 or reads data from the magnetic recording disk 62. The pivot assembly 68 supports the swing arm 64 so as to be swingable around the head rotation axis S with respect to the chassis 24. The voice coil motor 66 swings the swing arm 64 around the head rotation axis S, and moves the recording / reproducing head to a desired position on the upper surface of the magnetic recording disk 62. Voice coil motor 66 and pivot assembly 68 are constructed using known techniques for controlling the position of the head.

  The top cover 22 is a substantially rectangular thin plate, and has, for example, six screw through holes 22C provided in the periphery, a cover recess 22E, and a center hole 22D provided in the center of the cover recess 22E. The cover recess 22E is provided around the rotation axis R. The top cover 22 is formed in a predetermined shape by, for example, pressing an aluminum plate or a steel plate. The top cover 22 may be subjected to a surface treatment such as plating in order to prevent corrosion. The top cover 22 is fixed to the upper surface of the outer peripheral wall portion 24B of the chassis 24 using, for example, six peripheral screws 104. The six peripheral screws 104 correspond to the six screw through holes 22C and the six screw holes 24C, respectively. In particular, the top cover 22 and the upper surface of the outer peripheral wall 24 </ b> B are fixed to each other so that no leakage occurs from the joint portion to the inside of the disk drive device 100. Here, the inside of the disk drive device 100 is specifically a clean space 70 surrounded by the bottom plate portion 24 </ b> A of the chassis 24, the outer peripheral wall portion 24 </ b> B, and the top cover 22. The clean space 70 is designed to be sealed, that is, to prevent leak-in from the outside or leak-out to the outside. The clean space 70 is filled with clean air from which particles have been removed. Thereby, the adhesion of foreign matters such as particles from the outside of the clean space 70 to the magnetic recording disk 62 is suppressed, and the operation reliability of the disk drive device 100 is improved. The central screw 74 corresponds to the storage hole 10 </ b> A of the shaft 110. The top cover 22 is coupled to the shaft 110 by a center screw 74 passing through the center hole 22D and screwed into the storage hole 10A.

2 is a cross-sectional view taken along line AA in FIG.
Referring to FIG. 2, stationary body 2 further includes a shaft body 6, a stator core 32, and a coil 30. The shaft body 6 includes a shaft 110 and a shaft holding portion 112. The shaft 110 has a shaft flange 12 on one end side, that is, on the side opposite to the shaft holding portion 112. The shaft holding part 112 has a flange part 16 and a flange surrounding part 18.
The rotating body 4 includes a hub 26, a bearing body 8, a cap 48, and a cylindrical magnet 28 in a top view. The rotating body 4 and the stationary body 2 include a lubricant 20 that is continuously interposed in a part of the gap between the shaft body 6 and the bearing body 8 as a lubricating medium. The bearing body 8 includes a sleeve 42. The sleeve 42 is a member that surrounds the shaft 110 and may be referred to as a shaft surrounding member.
The shaft body 6, the bearing body 8, and the lubricant 20 constitute a fluid bearing unit together with a dynamic pressure generating groove to be described later.

  There are no particular restrictions on the material or method of forming the chassis 24. In the embodiment, as an example, the chassis 24 is integrally formed by molding an aluminum alloy by die casting. The chassis 24 may be formed, for example, by pressing a metal plate such as stainless steel or aluminum. In this case, the chassis 24 includes a stamping surface that is partially stamped by pressing. The chassis 24 may have a surface treatment layer such as nickel plating. Further, the chassis 24 may include, for example, a part that is partially formed of resin. Furthermore, the chassis 24 may have a coating layer such as an epoxy resin. The bottom plate portion 24A of the chassis 24 may be formed by stacking two or more plates.

  The chassis 24 includes an opening 24D centering on the rotation axis R of the rotating body 4 and a cylindrical protrusion 24E surrounding the opening 24D when viewed from above. The protruding portion 24E protrudes from the upper surface of the bottom plate portion 24A toward the hub 26 and extends beyond the flange surrounding portion 18 of the shaft holding portion 112.

  Further, the bottom plate portion 24A of the chassis 24 is provided with an annular recess 24N around the rotation axis R as viewed from above. The recess 24N is provided at a position facing the mounting portion 26J of the hub 26 described later in the axial direction. A part of a mounting portion 26J of the hub 26 described later enters the concave portion 24N. The entering portion of the hub 26 is provided around the rotation axis R. In addition, in the present embodiment, the bottom plate portion 24 </ b> A is provided with a counter wall 24 </ b> F that is circumferential when viewed from above, with the rotation axis R as the center. In the embodiment, the facing wall 24F is provided at a position included in the axial projection region of the magnet 28. Further, in the embodiment, the facing wall 24F is provided at a position facing a part of the inner peripheral surface of the hub 26 in the radial direction, and is continuous with the recess 24N in a sectional view.

  The first gap 202 between the facing wall 24F and the inner peripheral surface of the hub 26 can be set to, for example, 0.05 mm to 0.4 mm. The lower end surface of the mounting portion 26J of the hub 26 is opposed to the upper surface of the recess 24N of the chassis 24 in the axial direction to form a second gap 204. The second gap 204 extends in the radial direction, and can be, for example, 0.02 mm to 0.4 mm. The outer peripheral surface of the mounting portion 26J of the hub 26 is opposed to the inner peripheral surface of the recess 24N of the chassis 24 in the radial direction to form a third gap 206. The third gap 206 extends in the axial direction, and can be, for example, 0.05 mm to 0.4 mm. The lower end surface of the magnet 28 forms a fourth gap 208 opposite to the extending surface extending in the radial direction from the upper end of the opposing wall 24F of the chassis 24 in the axial direction. The fourth gap 208 extends in the radial direction, and can be, for example, 0.02 mm to 0.5 mm. In the embodiment, as an example, the first gap 202 is 0.1 mm to 0.3 mm, the second gap 204 is 0.05 mm to 0.2 mm, the third gap 206 is 0.1 mm to 0.3 mm, and the fourth gap 208 is 0.1 mm to 0.3 mm.

  The axial dimension of the first gap 202 is larger than the radial dimension, and can be, for example, five times or more the radial dimension. The radial dimension of the second gap 204 is larger than the axial dimension, and can be, for example, 5 times or more the axial dimension. The axial dimension of the third gap 206 is larger than the radial dimension, and can be, for example, five times or more the radial dimension. The axial dimension of the third gap 206 is larger than the radial dimension, and can be, for example, five times or more the radial dimension.

  The hub 26 has a hub facing surface that faces the chassis 24 in a region radially outward from the inner peripheral surface of the magnet 28, and the chassis 24 has a base facing surface that faces the hub facing surface via a facing gap. A gas dynamic pressure generating groove for generating dynamic pressure in the pump-in direction in the gas interposed in the facing gap when the hub 26 rotates with respect to the chassis 24 is provided on either the base facing surface or the hub facing surface. be able to. Since the gas dynamic pressure generating groove is provided in a region radially outward from the inner peripheral surface of the magnet 28, the gas existing in this region can be effectively pushed inward.

  As an example, a radial gas dynamic pressure generating groove that pushes the gas intervening in the first gap 202 into the magnet 28 side as the hub 26 rotates on any of the radially opposing surfaces that constitute the first gap 202. Can be provided. As another example, the gas intervening in the second gap 204 is pushed into the first gap 202 side by rotating the hub 26 in any one of the axially opposed surfaces constituting the second gap 204. A thrust gas dynamic pressure generating groove can be provided. As yet another example, the gas that intervenes in the third gap 206 is pushed into the second gap 204 side by rotating the hub 26 in any one of the radially opposed surfaces constituting the third gap 206. Another radial gas dynamic pressure generating groove can be provided. Such gas dynamic pressure generating grooves can be provided singly or in plural. The gas dynamic pressure generating groove can be formed in, for example, a spiral shape or a herringbone shape.

  In the embodiment, a spiral gas dynamic pressure generating groove 210 is formed in the lower end surface of the mounting portion 26J of the hub 26 and in the region facing the upper surface of the recess 24N of the chassis 24 in the axial direction. . In this case, diffusion of the vaporized lubricant 20 around the magnetic recording disk 62 can be suppressed.

  The dynamic pressure generating groove 210 can be provided by a method of directly forming at the lower end of the mounting portion 26J, a method of fixing another member on which the dynamic pressure generating groove 210 is formed in advance to the lower end of the mounting portion 26J, or the like. This separate member can be formed by a method of pressing from a metal material or the like, a method of molding from a resin material, or the like. The dynamic pressure generating groove 210 can be formed by a method such as press working, ball rolling, electro chemical machining, or cutting. Also, the dynamic pressure generating grooves can be provided on the respective opposing surfaces constituting the second gap 204 and the third gap 206 by the same method.

  The stator core 32 has an annular portion and, for example, 12 salient poles extending outward in the radial direction from the annular portion. The stator core 32 is joined by press-fitting, bonding, or a method using a combination of the inner peripheral side of the annular portion to the protruding portion 24E. The stator core 32 is formed, for example, by laminating 5 to 20 electromagnetic steel plates having a thickness of 0.2 mm to 0.35 mm and integrating them by caulking. In the embodiment, as an example, 12 electromagnetic steel sheets having a thickness of 0.2 mm are stacked. A surface layer is provided on the surface of the stator core 32. The surface of the stator core 32, that is, the surface layer is subjected to insulating coating such as electrodeposition coating or powder coating.

  The coil 30 is formed by winding a conductor wire around each salient pole of the stator core 32 a predetermined number of times. The coil 30 generates a field magnetic field along the salient pole when a drive current is passed. The conductor wire is formed by, for example, covering the surface of a core wire such as annealed copper with an insulating layer of urethane resin, for example. A lubricating substance is attached to the surface of the conductor wire so as to reduce the frictional resistance. Although there is no particular limitation on the lubricating substance, in this embodiment, a polyamide compound as a main component is attached to the wire as a lubricating substance, and attachment of hydrocarbons such as paraffin is minimized. Further, the coil 30 wound around the salient pole is immersed in a cleaning solution containing pure water, a surfactant or an ester, and cleaned while applying ultrasonic waves, thereby further reducing the amount of hydrocarbon adhering to the surface. As a result, the total amount of hydrocarbon adhering to the coil 30 is less than the total amount of polyamide compound adhering to the coil 30.

The hub 26 surrounds the sleeve 42 and is fixed to the sleeve 42, and extends toward the flange portion 16 from the sleeve surrounding portion 26 </ b> A facing the flange surrounding portion 18 and the sleeve surrounding portion 26 </ b> A. The extending portion 26B entering the inside of the flange surrounding portion 18, the disc portion 26D extending radially outward from the center portion, and the annular portion 26E extending axially downward from the outer peripheral portion of the disc portion 26D. And a mounting portion 26J extending radially outward from the lower outer peripheral surface of the annular portion 26E.
The sleeve surrounding portion 26A faces the projecting portion 24E via a gap in the radial direction and faces the flange surrounding portion 18 via the gap in the axial direction. The extending portion 26B faces the flange surrounding portion 18 via a gap in the radial direction and faces the flange portion 16 via the gap in the axial direction.

  The disk portion 26D, the annular portion 26E, and the placement portion 26J are each formed in a coaxial ring shape along the rotation axis R. As a result, the hub 26 has a substantially cup shape. The disk portion 26D, the annular portion 26E, and the placement portion 26J are integrally formed. The hub 26 is made of a steel material such as SUS430F having soft magnetism, for example. A central hole of a disk-shaped magnetic recording disk 62 is fitted into the annular portion 26E of the hub 26, and the magnetic recording disk 62 is placed on the placement portion 26J. At least a portion of the mounting portion 26J enters the recess 24N provided in the bottom plate portion 24A of the chassis 24. A gap between the concave portion 24N, the placement portion 26J, and the opposing wall 24F forms a labyrinth.

  Spacers 72 are provided to separate the four magnetic recording disks 62 from each other. Each of the spacers 72 has a hollow ring shape, and an inner peripheral surface thereof is fitted to the annular portion 26E. The spacer 72 is sandwiched between the lower magnetic recording disk 62 and the upper magnetic recording disk 62. A clamper 78 is provided to prevent the uppermost magnetic recording disk 62 from being detached from the hub 26. The clamper 78 has a hollow disk shape and is fixed to the upper surface of the hub 26 by a fastener (not shown) such as a screw. As a result, the clamper 78 presses the uppermost magnetic recording disk 62 so that the magnetic recording disk 62 does not come off the hub 26.

  The magnet 28 has a hollow ring shape, and its outer peripheral surface is fixed to the inner peripheral surface of the hub 26 by, for example, adhesion. The upper surface of the magnet 28 is in contact with a protruding portion that protrudes from the inner surface of the hub 26. The magnet 28 is made of, for example, a ferrite magnet material or a rare earth magnet material. As the binder, for example, a resin such as polyamide is included. The magnet 28 may be formed by laminating a ferrite magnet layer and a rare earth magnet layer. The surface of the magnet 28 has a surface layer by, for example, electrodeposition coating or spray coating. By having the surface layer, oxidation of the magnet 28 is suppressed, or peeling of the surface of the magnet 28 is suppressed. The magnet 28 is provided with, for example, 16 poles in the circumferential direction on the inner circumferential surface, and the inner circumferential surface is opposed to the outer circumferential surface of the salient pole of the core 32 in the radial direction via a gap. The height dimension, that is, the thickness of the magnet 28 can be 100% to 200% of the thickness of the stator core 32. In the embodiment, the thickness of the magnet 28 is approximately 180% of the thickness of the stator core 32.

  Next, the hydrodynamic bearing unit and its periphery will be described with reference to FIG. FIG. 3 is an enlarged sectional view showing the periphery of the shaft body 6 and the bearing body 8 in FIG. 2 in an enlarged manner. FIG. 3 mainly shows the left side of the rotation axis R. The hydrodynamic bearing unit has a gas-liquid interface between the lubricant 20 and the atmosphere gas in the gap between the shaft body 6 and the bearing body 8. In the embodiment, a first gas-liquid interface 124 described later, which is a gas-liquid interface on the base side, is exposed in a region sandwiched between the chassis 24 and the hub 26. Further, in this fluid dynamic bearing unit, a second gas-liquid interface 122 which will be described later, which is a gas-liquid interface on the hub side, is exposed in a region opening in the axial direction on the side far from the chassis 24 of the hub 26.

  First, the configuration of the shaft body 6 will be described in detail. The shaft holding portion 112 of the shaft body 6 includes the flange portion 16 and the flange surrounding portion 18 as described above. A shaft insertion hole 16B is formed in the center of the flange portion 16 coaxially with the rotation axis R. The flange surrounding portion 18 protrudes from the outer periphery of the flange portion 16 toward the hub 26. As for the shaft holding part 112, the flange part 16 and the flange surrounding part 18 are integrally formed, for example. In this case, the manufacturing error of the shaft holding part 112 can be reduced, and the labor of joining can be saved. Alternatively, the deformation of the shaft holding portion 112 with respect to the impact load can be suppressed. The shaft holding part 112 is formed by cutting from a metal material such as SUS303, for example. The shaft holder 112 may be formed using other materials such as resin, or other methods such as press working or molding, depending on the application or design restrictions of the disk drive device 100.

  The shaft holding portion 112 fits the flange surrounding portion 18 into the opening 24D of the chassis 24, and adheres the outer peripheral surface of the flange surrounding portion 18 to the inner peripheral surface of the opening 24D by, for example, an adhesive 76. Fixed to. The flange encircling portion 18 has an upper end 18C located, for example, in the axially arranged region of the second radial dynamic pressure generating groove 50, which will be described later, or on the upper side thereof, and the sleeve encircling portion of the hub 26 via a gap. Opposite 24A.

  As described above, the shaft 110 includes the shaft flange 12 on one end side. The shaft flange 12 is disposed so as to cover the upper surface of the sleeve 42 with a gap in the axial direction, and is opposed to the sleeve surrounding portion 26A of the hub 26 with a gap in the radial direction. The shaft flange 12 has a tapered surface 12 </ b> J on the outer peripheral surface thereof such that the distance in the radial direction from the rotation axis R increases as it approaches the chassis 24. Further, the shaft flange 12 is formed with an annular groove 12A on the inner peripheral side in a top view. A part of a cap 48 to be described later enters the groove 12A through a gap.

  In addition, the shaft 110 has an accommodation hole 10 </ b> A for accommodating a fastener such as a screw 74 at one end, that is, the end on the side where the shaft flange 12 is formed. The other end of the shaft 110 is inserted into the shaft insertion hole 16B of the flange portion 16, and is fixed by, for example, an interference fit. This interference fit is realized by, for example, press-fitting the shaft 110 into the shaft insertion hole 16B, shrink fitting, or cooling the shaft 110 with liquid nitrogen and inserting it into the shaft insertion hole 16B to return to room temperature. Is done. In this interference fit, adhesion may be used in combination.

  The shaft 110 and the shaft flange 12 are integrally formed. In this case, manufacturing errors between the shaft 110 and the shaft flange 12 can be reduced, and the labor of joining can be saved. Note that the shaft flange 12 may be formed separately from the shaft 110 in accordance with application and design restrictions.

  The shaft 110 is formed from a steel material such as SUS420J2, SUS430, or SUS303 by cutting or grinding. The shaft 110 may be quenched to increase hardness. The shaft 110 may be polished on the outer peripheral surface 10C or the lower surface 12C of the shaft flange 12 in order to improve dimensional accuracy. The shaft 110 may be formed using other materials such as resin, or other methods such as press working or molding.

  Next, the configuration of the bearing body 8 will be described in detail. The bearing body 8 includes a substantially cylindrical sleeve 42 that surrounds an intermediate portion of the shaft 110, that is, a portion between the shaft flange 12 and the flange portion 16. The sleeve 42 is coupled to the sleeve surrounding portion 26 </ b> A of the hub 26. The upper end of the sleeve 42 is opposed to the lower surface 12C of the shaft flange 12 via a gap in the axial direction, and the lower end thereof is opposed to the upper surface 16A of the flange 16 via the gap in the axial direction. With this configuration, the sleeve 42 can rotate with respect to the shaft 110, and as a result, the hub 26 coupled to the sleeve 42 is rotatably supported with respect to the chassis 24.

  The bearing body 8 is formed by cutting a metal material such as SUS430, for example. The bearing body 8 may have a surface layer formed by, for example, electroless nickel plating. The bearing body 8 may be formed of another material such as brass, for example.

The sleeve 42 has a hollow and substantially cylindrical shape, and includes an inner peripheral surface 42A, an outer peripheral surface 42B, an upper surface 42C, and a lower surface 42D. In the sleeve 42, the inner peripheral surface 42A surrounds the shaft 110 through a gap.
In the radial gap between the inner peripheral surface 42A of the sleeve 42 and the outer peripheral surface 10C of the shaft 110, a first radial dynamic pressure bearing portion 80, a lubricant reservoir portion 82, and a second radial dynamic pressure bearing portion 84 are sequentially arranged from the top. And are provided. The first radial dynamic pressure bearing portion 80 is provided above the second radial dynamic pressure bearing portion 84 so as to be spaced apart from the second radial dynamic pressure bearing portion 84, and the first radial dynamic pressure bearing portion 80 and the second radial dynamic pressure bearing portion 80. A lubricant reservoir portion 82 is provided between the bearing portions 84. A first radial dynamic pressure generating groove 52 that generates radial dynamic pressure is provided in a region corresponding to the first radial dynamic pressure bearing portion 80 in the inner peripheral surface 42A of the sleeve 42. The first radial dynamic pressure generating groove 52 may be provided on the outer peripheral surface 10 </ b> C of the shaft 110 instead of the sleeve 42. A second radial dynamic pressure generating groove 50 for generating a radial dynamic pressure is provided in a region corresponding to the second radial dynamic pressure bearing portion 84 in the inner peripheral surface 42A of the sleeve 42. The second radial dynamic pressure generating groove 50 may be provided on the outer peripheral surface 10 </ b> C of the shaft 110 instead of the sleeve 42. A region corresponding to the lubricant reservoir portion 82 on the inner peripheral surface 42A of the sleeve 42 is provided with a large-diameter portion that is recessed outward in the radial direction. In the description of the present embodiment, a region where the second radial dynamic pressure generating groove 50 and the first radial dynamic pressure generating groove 52 are provided may be referred to as a radial dynamic pressure generating groove arrangement region.
Further, the sleeve 42 includes a communication passage BP that extends in the axial direction and communicates with a first thrust facing portion 86 and a second thrust facing portion 88 described later on the outer peripheral surface 42B. The communication path BP is formed in the sleeve 42 so as to include a groove extending in the axial direction from the upper end to the lower end on the outer peripheral surface 42B.

  Between the shaft flange 12 and the sleeve 42, a first thrust facing portion 86 is provided in a gap where the lower surface 12C and the upper surface 42C face each other in the axial direction. A first thrust dynamic pressure generating groove 54 is provided in a region corresponding to the first thrust facing portion 86 of the upper surface 42C of the sleeve 42 in order to generate a thrust dynamic pressure. The first thrust dynamic pressure generating groove 54 may be provided in a region corresponding to the first thrust facing portion 86 of the lower surface 12 </ b> C of the shaft flange 12 instead of the sleeve 42. On the other hand, a second thrust facing portion 88 is provided between the flange portion 16 and the sleeve 42 in a gap where the upper surface 16A and the lower surface 42D face each other in the axial direction. A second thrust dynamic pressure generating groove 56 is provided in a region corresponding to the second thrust facing portion 88 on the lower surface 42D of the sleeve 42 in order to generate a thrust dynamic pressure. The second thrust dynamic pressure generating groove 56 may be provided in a region corresponding to the second thrust facing portion 88 on the upper surface 16A of the flange portion 16 instead of the sleeve 42. In the description of the present embodiment, a region where the first thrust dynamic pressure generating groove 54 or the second thrust dynamic pressure generating groove 56 is provided may be referred to as a thrust dynamic pressure generating groove arrangement region.

  The first thrust dynamic pressure generating groove 54 and the second thrust dynamic pressure generating groove 56 are, for example, spiral. The first thrust dynamic pressure generating groove 54 and the second thrust dynamic pressure generating groove 56 may have other shapes such as a herringbone shape. The second radial dynamic pressure generating groove 50, the first radial dynamic pressure generating groove 52, the first thrust dynamic pressure generating groove 54, and the second thrust dynamic pressure generating groove 56 are, for example, press work, ball rolling process, and electrolytic etching process. (Electro Chemical Machining), formed by methods such as cutting. These dynamic pressure generating grooves may be formed by different methods.

  The outer peripheral surface of the extending portion 26B has an inclined surface 26BA whose outer diameter decreases in the region facing the inner peripheral surface 18A of the flange surrounding portion 18 in the radial direction and closer to the upper end thereof. The radial gap between the inclined surface 26BA and the inner peripheral surface 18A forms a tapered space that gradually increases toward the upper side in the axial direction. The inclined surface 26BA and the inner peripheral surface 18A are in contact with a second gas-liquid interface 122 of the lubricant 20 described later, and constitute a second capillary seal 92 that suppresses the scattering of the lubricant 20 by capillary force. For example, the second gas-liquid interface 122 is located in the axial direction of the second radial dynamic pressure generating groove 50 or on the upper side thereof. For example, the second gas-liquid interface 122 is provided on the radially outer side of the first thrust facing portion 86 and the second thrust facing portion 88.

  The sleeve surrounding portion 26 </ b> A is opposed to the shaft flange 12 via a gap in the radial direction on the upper side of the sleeve 42. The radial clearance between the inner peripheral surface 26AA of the sleeve surrounding portion 26A and the tapered surface 12J of the shaft flange 12 forms a tapered space that gradually widens upward. The inner peripheral surface 26AA and the tapered surface 12J are in contact with the first gas-liquid interface 124 of the lubricant, and constitute a first capillary seal 90 that suppresses scattering of the lubricant 20 by capillary force.

  The cap 48 is in the shape of a hollow ring that is thin in the axial direction, and is formed by cutting from a stainless material such as SUS303 or SUS430, for example. The cap 48 may be formed from other metal materials or resin materials by pressing or molding. The cap 48 is fixedly provided on the bearing body 8 so that the inner peripheral side surrounds the shaft body 6 via a gap. Specifically, the inner peripheral surface of the cap 48 faces the outer peripheral surface of the upper end of the shaft 110 in a non-contact state, and the outer peripheral surface of the cap 48 is bonded and fixed to the upper end surface of the sleeve surrounding portion 26A. The cap 48 covers the first gas-liquid interface 124 and a part of the shaft flange 12. A circumferential convex portion 48 </ b> E that extends downward about the rotation axis R is provided on the inner peripheral portion of the cap 48. A portion of the circumferential convex portion 48E enters the circumferential groove 12A that is provided around the rotation axis R on the upper surface of the shaft flange 12 in the axial direction. The cap 48 is fixedly provided on the shaft body 6 and may be provided in a non-contact state with the hub 26.

  Next, the lubricant will be described. As the lubricant, various materials such as synthetic oil, mineral oil and ionic liquid can be used. In the lubricant 20 of the embodiment, as an example, a synthetic oil mainly composed of an ester compound is used as a base oil. The lubricant 20 of the embodiment has a fluorescence ability. In the description of this embodiment, the term “fluorescence” refers to fluorescence in a broad sense including phosphorescence in addition to fluorescence in a narrow sense. For example, the base oil itself may contain a fluorescent material having fluorescent ability. In the lubricant 20 of the embodiment, a phosphor is added to the base oil. There are no particular restrictions on the phosphor, but examples include inorganic substances including rare earth salts, uranyl salts, platinum cyanide salts, tungstates, benzene, aniline, anthracene, phthalein dyes, porphyrin dyes, cyanine dyes. Various fluorescent materials such as organic materials including the like can be used. As an example, the lubricant 20 according to the embodiment is added with fluorescent material fluorescein. For example, fluorescein emits visible light having a green spectrum when it is irradiated with ultraviolet rays having a wavelength shorter than that of visible light. This is considered to be due to the photoluminescence phenomenon.

  When a phosphor is added to the lubricant, the phosphor may chemically react with the lubricant base oil to deteriorate the base oil. For this reason, a substance with little deterioration of the base oil is desirable as the phosphor. Further, when used at a temperature equal to or higher than the boiling point of the phosphor, the phosphor easily volatilizes and adheres to the surface of the recording disk, which may cause a failure. For this reason, the boiling point of the phosphor contained in the lubricant 20 of the embodiment is higher than the boiling point of water. In this case, volatilization of the phosphor is suppressed when used in a temperature range below the boiling point of water. In other words, in this case, the disk drive device 100 can be used even at a temperature close to the boiling point of water as long as it is below the boiling point of water.

  The phosphor content of the lubricant can be, for example, 0.001% by weight or more. In this case, the lubricant emits fluorescence by applying light of a predetermined property. In the embodiment, the phosphor content of the lubricant 20 is, for example, 0.01% by weight or more. In this case, the lubricant 20 emits stronger fluorescence by applying predetermined light as compared with the case where the content is 0.001 wt%. If the phosphor content of the lubricant is increased, the cost of the lubricant may increase. In the embodiment, the phosphor content of the lubricant 20 is, for example, 1% by weight or less. In this case, it has been found that the cost increase of the lubricant 20 is within a practical range.

  Next, the intervening region of the lubricant 20 will be described. The lubricant 20 is continuously interposed from the first gas-liquid interface 124 to the second gas-liquid interface 122 in the gap between the bearing body 8 and the shaft body 6. Specifically, the lubricant 20 includes a gap between the tapered surface 12J and the inner peripheral surface 26AA, a gap between the shaft flange 12 and the sleeve 42, a radial gap between the sleeve 42 and the shaft 110, a sleeve 42 and a flange. It is interposed in a region including a gap between 16 parts, a gap between the extending part 26B and the flange part 16, and a gap between the inclined surface 26BA and the inner peripheral surface 18A. In other words, the lubricant 20 includes the first thrust facing portion 86, the first radial dynamic pressure bearing portion 80, the lubricant reservoir portion 82, and the second portion from the first gas-liquid interface 124 to the second gas-liquid interface 122. A region including the radial bearing portion 84 and the second thrust facing portion 88 is continuously filled. Furthermore, the lubricant 20 is continuously filled in a region including the communication path BP from the first gas-liquid interface 124 to the second gas-liquid interface 122.

  Regarding the lubricant 20, the configuration of the labyrinth will be described below. As described above, the sleeve surrounding portion 26A faces the protruding portion 24E via a gap in the radial direction and faces the upper end 18C of the flange surrounding portion 18 via the gap in the axial direction. Therefore, the respective gaps between the sleeve surrounding portion 26A and the protruding portion 24E and the upper end 18C form a first labyrinth. Further, the lower end of the mounting portion 26J of the hub 26 enters the concave portion 24N of the chassis 24 to form a second labyrinth including the fourth gap 208, the first gap 202, the second gap 204, and the third gap 206. . Further, the gap between the cap 48 and the shaft flange 12 forms a third labyrinth.

  Here, the operation of the hydrodynamic bearing unit will be described. When the bearing body 8 rotates relative to the shaft body 6, the second radial dynamic pressure generating groove 50, the first radial dynamic pressure generating groove 52, the first thrust dynamic pressure generating groove 54, and the second thrust dynamic pressure are generated. Each of the grooves 56 generates a dynamic pressure in the lubricant 20. The rotating body 4 connected to the bearing body 8 by this dynamic pressure is supported in the radial direction and the axial direction in a non-contact state with respect to the stationary body 2 connected to the shaft body 6.

Next, an example of a method for producing the disk drive device 100 according to the embodiment will be described.
First, the sleeve 42 is fixed to the hub 26 by, for example, adhesion. After that, the sleeve 42 is sandwiched between the shafts 110 and the shaft holding part 112, and the shaft holding part 112 and the shaft 110 are joined together by press-fitting and bonding. Hereinafter, an assembly of the hub 26, the sleeve 42, the shaft holding portion 112, and the shaft 110 is referred to as a subassembly. Thereafter, the lubricant 20 is filled into the lubricant filling region of the subassembly. For example, the sub-assembly is left in a reduced-pressure atmosphere, and air in the lubricant filling region is extracted. Thereafter, the lubricant 20 is attached to the gap between the hub 26 and the shaft flange 12, for example. Then, the bearing unit is completed by returning the atmosphere to atmospheric pressure and filling the lubricant filling region of the subassembly with the lubricant 20.

  Thereafter, the first gas-liquid interface 124 of the lubricant 20 is observed for the bearing unit filled with the lubricant 20 to confirm that the first gas-liquid interface 124 exists in a predetermined position range. At this time, if the lubricant is substantially transparent, it may take a lot of time to confirm. In the embodiment, since the lubricant 20 has fluorescence ability, for example, it emits output light having a predetermined wavelength by irradiating ultraviolet rays as input light. FIG. 4 is a cross-sectional view showing a process of obtaining output light by irradiating the lubricant 20 with input light. FIG. 4 corresponds to FIG. In this step, the first gas-liquid interface 124 in the gap between the hub 26 of the bearing unit and the shaft flange 12 is irradiated with ultraviolet light having a predetermined wavelength as input light (Input light), and output light (Output light) is, for example, blue And green fluorescence. In this case, the confirmation of the first gas-liquid interface 124 is facilitated, and the labor for confirmation is reduced, so that productivity is improved. In this case, since output light with a predetermined wavelength is obtained, the position of the first gas-liquid interface 124 can be predicted by measuring the intensity of the output light with the predetermined wavelength. Confirmation becomes easier.

  Thereafter, the cap 48 and the magnet 28 are fixed to the hub 26 by bonding. Thereafter, the chassis 24 to which the stator core 32 with the coil 30 attached is fixed, and the bearing unit is fixed to the chassis 24 by bonding. Thereafter, the magnetic recording disk 62, the clamper 78, and the spacer 72 are attached. Thereafter, the data read / write unit 60 and the top cover 22 are attached. Thereafter, the disk drive device 100 is completed through a process such as a predetermined inspection. The above-described process is an example, and the disk drive device 100 may be produced by a different process.

  Next, the operation of the disk drive device 100 configured as described above will be described. In order to rotate the magnetic recording disk 62, a three-phase drive current is supplied to the coil 30. When the drive current flows through the coil 30, a field magnetic flux is generated along the salient pole of each stator core 32. Torque is applied to the magnet 28 by the interaction between the field magnetic flux and the magnetic flux of the drive magnetic pole of the magnet 28, and the hub 26 and the magnetic recording disk 62 fitted thereto rotate. At the same time, the voice coil motor 66 swings the swing arm 64, so that the recording / reproducing head moves back and forth on the magnetic recording disk 62. The recording / reproducing head converts the magnetic data recorded on the magnetic recording disk 62 into an electric signal and transmits it to a control board (not shown), and also transmits the data sent from the control board in the form of an electric signal on the magnetic recording disk 62. Is written as magnetic data.

  The disk drive device 100 of the present embodiment configured as described above has the following advantages.

  In the disk drive device 100, the dynamic pressure generating groove 210 is provided on the lower end surface of the mounting portion 26 </ b> J of the hub 26 that forms the second gap 204, so that the gas interposed in the second gap 204 when the hub 26 rotates. Is pushed out to the inside of the hub 26 and the vaporized lubricant 20 can be prevented from reaching the clean space 70.

  In the disk drive device 100, the sleeve surrounding portion 26A, the protruding portion 24E, and the upper end 18C of the flange surrounding portion 18 form a first labyrinth. This first labyrinth suppresses scattering and evaporation of the lubricant 20 from the second gas-liquid interface. Further, the lower end of the mounting portion 26J of the hub 26 enters the recess 24N of the chassis 24 to form a second labyrinth. Even if the vaporized lubricant 20 exceeds the first labyrinth and reaches the inside of the hub 28, that is, the region where the coil 30 and the stator core 32 are disposed, this second labyrinth further passes through the recess 24N due to passage resistance. Thus, reaching the outside of the hub 26, that is, the placement area (clean space 70) of the magnetic recording disk 62 is suppressed.

  Further, the gap between the cap 48 and the groove 12A of the shaft flange 12 forms a third labyrinth. The third labyrinth suppresses scattering and evaporation of the lubricant 20 from the first gas-liquid interface 124. For this reason, the disk drive device 100 can suppress vaporization and condensation of the lubricant 20 on the surface of the magnetic recording disk 62, and thereby further increase the recording capacity.

  Further, since the first to third labyrinths can suppress the evaporation of the lubricant 20 and the like, the time until the disk drive device 100 reaches the end of its life due to the lack of the lubricant 20 can be extended. The life of the driving device 100 can be extended.

  A relative pressure between the bearing body 8 and the shaft body 6 may cause a pressure difference in the lubricant between the first radial dynamic pressure bearing portion 80 and the second radial dynamic pressure bearing portion 84. Due to this pressure difference, the lubricant 20 easily leaks from the first capillary seal 90 and the second capillary seal 92. However, in the present embodiment, the pressure between the first capillary seal 90 and the second capillary seal 92 is provided by providing the communication path BP that communicates the first thrust facing portion 86 and the second thrust facing portion 88. The difference becomes smaller. Therefore, leakage of the lubricant 20 can be suppressed.

  In the disk drive device 100, when the bearing body 8 and the shaft body 6 rotate relative to each other, the first radial dynamic pressure bearing portion 80 pushes the lubricant 20 toward the first thrust facing portion 86. It is possible to suppress a decrease in dynamic pressure in the vicinity of the boundary between 86 and the first radial dynamic pressure bearing portion 80. Further, since the second radial dynamic pressure bearing portion 84 pushes the lubricant 20 toward the second thrust facing portion 88, the dynamic pressure near the boundary between the second thrust facing portion 88 and the second radial dynamic pressure bearing portion 84 is reduced. Reduction can be suppressed. As a result, the possibility that the rotating body 4 contacts the stationary body 2 can be reduced.

  In the disk drive device 100, since the shaft flange 12 has a portion formed integrally with the shaft 110, the possibility of the shaft flange 12 falling off from the shaft 110 is suppressed, and the shaft flange in the usage state of the disk drive device 100 is suppressed. Decrease in bonding strength between the shaft 12 and the shaft 110 can be prevented.

  In the disk drive device 100, the flange surrounding portion 18 has an upper end 18C positioned in the axial direction of the second radial dynamic pressure generating groove 50 or on the upper side thereof. The volume of the gap between the extending portion 26 and the inclined surface 26BA can be increased. Further, since the second gas-liquid interface 122 is located in the axial direction in the region where the second radial dynamic pressure generating groove 50 is disposed or on the upper side thereof, the second gas-liquid interface 122 holds a large amount of the lubricant 20 and lacks the lubricant 20. Can reduce the possibility of failure.

  When a current flows through the coil and the temperature rises due to Joule heat, paraffin components such as hydrocarbon adhering to the coil surface volatilize and diffuse into the atmosphere, and eventually reach the surface of the magnetic recording disk. The volatile component is condensed and gradually accumulates on the surface of the magnetic recording disk, thereby hindering the operation of the disk drive device. In the worst case, it may cause a failure of the disk drive. However, in the disk drive device 100, since the total amount of hydrocarbon adhering to the coil 30 is smaller than the total amount of polyamide compound adhering to the coil 30, the possibility of occurrence of failure due to volatilization of the hydrocarbon can be reduced.

  In the disk drive device 100, since the lubricant 20 has fluorescent ability, it can be easily detected even when the lubricant 20 adheres to an unintended location in the production process. Further, even when the lubricant 20 leaks from the gap between the members, it can be easily detected.

  The configuration and operation of the disk drive device according to the disk drive device according to the embodiment have been described above. Those skilled in the art will understand that these are merely examples, and that various combinations of these components are possible, and that such configurations are within the scope of the present invention.

  In the above embodiment, the example in which the lubricant 20 in which the phosphor is added to the base oil mainly composed of the ester compound is used is described, but the present invention is not limited thereto. For example, a lubricant containing an ionic liquid may be used. By including the ionic liquid, the vaporization of the lubricant is suppressed, and the lubricant diffusing into the disk drive device can be reduced to reduce the deposition on the disk. Although there is no restriction | limiting in particular as an ionic liquid, The ionic liquid described in Unexamined-Japanese-Patent No. 2007-120653 can be used as an example. The lubricant containing the ionic liquid can contain the phosphor described above.

  Although the case where the rotating body 4 is coupled to the bearing body 8 and the shaft body 6 is coupled to the stationary body 2 has been described in the above embodiment, the present invention is not limited to this. A configuration in which the rotating body 4 is coupled to the shaft body 6 and the bearing body 8 is coupled to the stationary body 2 may be employed.

  In the embodiment, the case where the stator core is surrounded by the magnet has been described, but the present invention is not limited to this. For example, a configuration in which the magnet is surrounded by the stator core may be employed.

  In the embodiment, the case where the first thrust dynamic pressure generating groove 54 is provided in the region corresponding to the first thrust facing portion 86 of the upper surface 42C of the sleeve 42 has been described, but the present invention is not limited to this. For example, the first thrust facing portion 86 may adopt a configuration in which no thrust dynamic pressure generating groove is provided on either the upper surface 42C or the lower surface 12C of the shaft flange 12.

100, 200 Disk drive device 2 Stationary body 4 Rotating body 6 Shaft body 8 Bearing body 12 Shaft flange 18, 218 Flange surrounding portion 22 Top cover 24, 224 Chassis 26 Hub 28 Magnet 30 Coil 32 Stator core 42 Sleeve 48 Cap 50 Second Radial dynamic pressure generating groove 52 First radial dynamic pressure generating groove 54 First thrust dynamic pressure generating groove 56 Second thrust dynamic pressure generating groove 60 Data read / write section 62 Magnetic recording disk 64 Swing arm 66 Voice coil motor 68 Pivot assembly 70 Clean space 72 Spacer 74 Center screw 76 Sealant 78 Clamper 80 First radial dynamic pressure bearing portion 82 Lubricant reservoir 84 Second radial dynamic pressure bearing portion 86 First thrust facing portion 88 Second thrust facing portion 104 Peripheral screw 110 Shaft BP Communication path R Rotating shaft

JP 2008-275074 A JP 2011-150770 A

Claims (12)

Base and
A hub having a disk mounting portion and a ring-shaped magnet fixed to the inner peripheral surface;
A hydrodynamic bearing unit that rotatably supports the hub with respect to the base by generating fluid dynamic pressure in the lubricant;
With
The hub has a hub facing surface facing the base in a region radially outward from the inner peripheral surface of the magnet,
The base has a base facing surface that faces the hub facing surface via a facing gap;
A gas dynamic pressure generating groove for generating a dynamic pressure in the pump-in direction in the gas interposed in the facing gap when the hub rotates with respect to the base is provided on either the hub facing surface or the base facing surface. A disk drive device characterized by that. The hub has a peripheral wall portion including an end surface of the peripheral wall portion facing the base in the axial direction,
The base has a thrust facing surface that faces the end surface of the peripheral wall portion in the axial direction via an axial gap,
A gas thrust dynamic pressure generating groove for generating a dynamic pressure in the pump-in direction in the gas interposed in the axial gap when the hub rotates with respect to the base is provided on either the peripheral wall end face or the thrust facing surface. The disk drive device according to claim 1, wherein the disk drive device is provided. The hub has an outer peripheral extending portion extending radially outward from an outer peripheral surface of the peripheral wall portion;
The base has a radially opposing surface that faces the extending portion outer peripheral surface of the outer peripheral extending portion in a radial direction via a radial gap,
An outer gas radial dynamic pressure that generates a dynamic pressure in the pump-in direction in the gas interposed in the radial gap when the hub rotates relative to the base on either the outer peripheral surface of the extension part or the radial facing surface 3. The disk drive device according to claim 1, further comprising a generation groove. The base is formed in an annular shape on the hub side surface of the base, and has a facing wall that faces at least a part of the inner peripheral surface of the hub of the peripheral wall portion in the radial direction via a facing gap.
An inner gas radial dynamic pressure generating groove that generates dynamic pressure in the pump-in direction in the gas interposed in the facing gap when the hub rotates with respect to the base is formed on either the facing wall or the inner peripheral surface of the hub. 4. The disk drive device according to claim 1, wherein the disk drive device is provided. The base is provided with a base recess including an annular recess provided around the rotation axis R and including the base-facing surface;
5. The disk drive device according to claim 1, wherein the hub is provided with a cylindrical hub entry portion including the hub facing surface and entering the base recess.   6. The disk drive device according to claim 5, wherein a thrust gap provided between the end face of the hub entry portion and the base recess and extending in the radial direction is 0.02 mm or more and 0.4 mm or less.   The radial gap provided between the inner peripheral surface of the hub entry portion and the base recess and extending in the axial direction is 0.05 mm or more and 0.4 mm or less. Disk drive device.   8. The radial gap provided between the outer peripheral surface of the hub entry portion and the base recess and extending in the axial direction is 0.05 mm or more and 0.4 mm or less, according to claim 5. The disk drive described. The hydrodynamic bearing unit has a base side gas-liquid interface of the lubricant exposed in a region between the base and the hub,
The hub has a hub protrusion extending around the hydrodynamic bearing unit and extending toward the base;
The base has a base protrusion extending around the hub protrusion and extending toward the hub;
9. The gap between the hub protrusion and the base protrusion extends in the axial direction to form a labyrinth that communicates the base-side gas-liquid interface and the opposing gap. The disk drive device described in 1. The hydrodynamic bearing unit has a hub-side gas-liquid interface of the lubricant exposed in a region opening in the axial direction on the side farther from the base of the hub,
A cap is provided on the upper surface of the hub so as to cover the hub-side gas-liquid interface around the shaft,
The hydrodynamic bearing unit is formed with an annular groove into which a part of the cap enters,
The disk drive device according to claim 1, wherein a gap between a part of the cap and the groove forms a bent labyrinth. Base and
A hub having a disk mounting portion and a ring-shaped magnet fixed to the inner peripheral surface;
A hydrodynamic bearing unit that rotatably supports the hub with respect to the base by generating fluid dynamic pressure in the lubricant;
With
The hub has a hub facing surface facing the base in a region radially outward from the inner peripheral surface of the magnet,
The base has a base facing surface that faces the hub facing surface via a facing gap;
A gas dynamic pressure generating groove for generating dynamic pressure in the pump-in direction in the gas interposed in the facing gap when the hub rotates with respect to the base is provided on either the hub facing surface or the base facing surface. ,
The disk drive device according to claim 1, wherein the lubricant contains an ionic liquid. A fluid bearing that rotatably supports the rotating body with respect to the stationary body by generating fluid dynamic pressure in the lubricant;
The rotating body and the stationary body are provided on any one of opposing surfaces facing each other across the facing gap, and when the rotating body rotates with respect to the stationary body, fluid dynamic pressure is applied to the gas interposed in the facing gap. A gas dynamic pressure generating groove to be generated;
A disk drive device comprising:

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