US20130321952A1 - Bearing mechanism, motor and disk drive apparatus - Google Patents
Bearing mechanism, motor and disk drive apparatus Download PDFInfo
- Publication number
- US20130321952A1 US20130321952A1 US13/785,297 US201313785297A US2013321952A1 US 20130321952 A1 US20130321952 A1 US 20130321952A1 US 201313785297 A US201313785297 A US 201313785297A US 2013321952 A1 US2013321952 A1 US 2013321952A1
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- US
- United States
- Prior art keywords
- gap
- thrust plate
- sleeve
- radial
- bearing mechanism
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C32/00—Bearings not otherwise provided for
- F16C32/06—Bearings not otherwise provided for with moving member supported by a fluid cushion formed, at least to a large extent, otherwise than by movement of the shaft, e.g. hydrostatic air-cushion bearings
- F16C32/0629—Bearings not otherwise provided for with moving member supported by a fluid cushion formed, at least to a large extent, otherwise than by movement of the shaft, e.g. hydrostatic air-cushion bearings supported by a liquid cushion, e.g. oil cushion
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B19/00—Driving, starting, stopping record carriers not specifically of filamentary or web form, or of supports therefor; Control thereof; Control of operating function ; Driving both disc and head
- G11B19/20—Driving; Starting; Stopping; Control thereof
- G11B19/2009—Turntables, hubs and motors for disk drives; Mounting of motors in the drive
- G11B19/2036—Motors characterized by fluid-dynamic bearings
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C17/00—Sliding-contact bearings for exclusively rotary movement
- F16C17/10—Sliding-contact bearings for exclusively rotary movement for both radial and axial load
- F16C17/102—Sliding-contact bearings for exclusively rotary movement for both radial and axial load with grooves in the bearing surface to generate hydrodynamic pressure
- F16C17/107—Sliding-contact bearings for exclusively rotary movement for both radial and axial load with grooves in the bearing surface to generate hydrodynamic pressure with at least one surface for radial load and at least one surface for axial load
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
- F16C33/02—Parts of sliding-contact bearings
- F16C33/04—Brasses; Bushes; Linings
- F16C33/06—Sliding surface mainly made of metal
- F16C33/10—Construction relative to lubrication
- F16C33/1025—Construction relative to lubrication with liquid, e.g. oil, as lubricant
- F16C33/106—Details of distribution or circulation inside the bearings, e.g. details of the bearing surfaces to affect flow or pressure of the liquid
- F16C33/107—Grooves for generating pressure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
- F16C33/02—Parts of sliding-contact bearings
- F16C33/04—Brasses; Bushes; Linings
- F16C33/06—Sliding surface mainly made of metal
- F16C33/10—Construction relative to lubrication
- F16C33/1025—Construction relative to lubrication with liquid, e.g. oil, as lubricant
- F16C33/106—Details of distribution or circulation inside the bearings, e.g. details of the bearing surfaces to affect flow or pressure of the liquid
- F16C33/1085—Channels or passages to recirculate the liquid in the bearing
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K5/00—Casings; Enclosures; Supports
- H02K5/04—Casings or enclosures characterised by the shape, form or construction thereof
- H02K5/16—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields
- H02K5/167—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields using sliding-contact or spherical cap bearings
- H02K5/1677—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields using sliding-contact or spherical cap bearings radially supporting the rotor around a fixed spindle; radially supporting the rotor directly
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
- H02K7/08—Structural association with bearings
- H02K7/085—Structural association with bearings radially supporting the rotary shaft at only one end of the rotor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C2370/00—Apparatus relating to physics, e.g. instruments
- F16C2370/12—Hard disk drives or the like
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
- F16C33/72—Sealings
- F16C33/74—Sealings of sliding-contact bearings
- F16C33/741—Sealings of sliding-contact bearings by means of a fluid
- F16C33/743—Sealings of sliding-contact bearings by means of a fluid retained in the sealing gap
- F16C33/745—Sealings of sliding-contact bearings by means of a fluid retained in the sealing gap by capillary action
Definitions
- the present invention relates to a bearing mechanism, and more specifically to a bearing mechanism for use in a motor.
- a motor provided with a fluidic dynamic-pressure bearing mechanism has been used as a motor for a disk drive apparatus.
- a bottom plate 10 a first bearing component 16, a second bearing component 18n and a fixed shaft 12 define a fixed component unit.
- Fluidic dynamic-pressure radial bearing units 22a and 22b are arranged between the fixed shaft 12 and a rotor component 14.
- a fluidic dynamic-pressure thrust bearing unit 26 is arranged between the first bearing component 16 and the rotor component 14.
- a pumping seal 36 is arranged between the second bearing component 18 and the rotor component 14.
- the rotor component 14 is provided with a circulation path 28.
- the circulation path 28 interconnects a radial outer region of the thrust bearing unit 26 and a radial inner region of the pumping seal 36.
- a seal gap 34 is provided at the radial outer side of the thrust bearing unit 26.
- a bearing mechanism includes a shaft portion, a sleeve portion, a lower opposing portion, a lower outer ring-shaped portion, and an upper opposing portion.
- the shaft portion is arranged about a center axis extending in an up-and-down direction.
- the shaft portion includes a cylindrical outer circumferential surface.
- the sleeve portion includes a through-hole arranged to accommodate the shaft portion.
- the sleeve portion is arranged to rotate about the center axis.
- the lower opposing portion extends radially outward from a lower portion of the shaft portion.
- the lower opposing portion includes an upper surface axially opposed to a lower end surface of the sleeve portion through a lower thrust gap.
- the lower outer ring-shaped portion includes a cylindrical or substantially cylindrical inner circumferential surface arranged to surround at least a portion of an outer circumferential surface of the sleeve portion.
- the relative position of the lower outer ring-shaped portion is fixed with respect to the lower opposing portion.
- the upper opposing portion extends radially outward from the shaft portion at an upper side of the sleeve portion.
- the upper opposing portion includes a lower surface axially opposed to an upper end surface of the sleeve portion through an upper thrust gap.
- a radial dynamic-pressure bearing portion is provided in a radial gap between the outer circumferential surface of the shaft portion and an inner circumferential surface of the sleeve portion.
- a lower thrust dynamic-pressure bearing portion is provided in the lower thrust gap.
- a lower seal portion is arranged in a lower seal gap between the outer circumferential surface of the sleeve portion and the inner circumferential surface of the lower outer ring-shaped portion.
- the lower seal portion is a pumping seal portion.
- An upper seal portion is arranged in an upper seal gap joined to the upper thrust gap.
- the sleeve portion includes a lower portion including a large-diameter portion and a small-diameter portion positioned below the large-diameter portion. The small-diameter portion is smaller in diameter than the large-diameter portion.
- the sleeve portion further includes a communication path joined to the upper seal gap.
- the communication path includes an opening portion opened in or near a border between the large-diameter portion and the small-diameter portion.
- the lower opposing portion includes an outer peripheral portion including an outer periphery protrusion portion radially opposed to an outer circumferential surface of the small-diameter portion and axially opposed to a lower surface of the large-diameter portion.
- a straight line interconnecting an outer edge of a lower surface of the small-diameter portion and an outer edge of the lower surface of the large-diameter portion on a cross section including the center axis extends across the outer periphery protrusion portion.
- a circulation path including the lower thrust gap, the radial gap, the upper thrust gap, and the communication pass communicates with the lower seal gap and the upper seal gap.
- a lubricant is filled in the circulation path, the lower seal gap and the upper seal gap.
- FIG. 1 is a sectional view of a disk drive apparatus according to a preferred embodiment of the present invention.
- FIG. 2 is a sectional view of a motor according to a preferred embodiment of the present invention.
- FIG. 3 is a sectional view of a bearing mechanism according to a preferred embodiment of the present invention.
- FIG. 4 is a sectional view of a sleeve body according to a preferred embodiment of the present invention.
- FIG. 5 is a plan view of a lower opposing portion according to a preferred embodiment of the present invention.
- FIG. 6 is a plan view of an upper thrust plate according to a preferred embodiment of the present invention.
- FIG. 7 is an enlarged sectional view showing a lower horizontal communication path according to a preferred embodiment of the present invention and its vicinity.
- FIG. 8 is a plan view of a lower thrust plate according to a preferred embodiment of the present invention.
- FIG. 9 is an enlarged sectional view showing an upper horizontal communication path according to a preferred embodiment of the present invention and its vicinity.
- FIG. 10 is a schematic diagram showing a lower thrust plate according to a preferred embodiment of the present invention and its vicinity.
- FIG. 11 is a schematic diagram showing a lower thrust plate according to a preferred embodiment of the present invention and its vicinity.
- FIG. 12 is a schematic diagram showing a lower thrust plate according to a preferred embodiment of the present invention and its vicinity.
- FIG. 13 is a plan view of another example of the lower thrust plate according to a preferred embodiment of the present invention.
- FIG. 14 is a sectional view of a further example of the lower thrust plate according to a preferred embodiment of the present invention.
- FIG. 15 is a view showing a still further example of the lower thrust plate and the sleeve body according to a preferred embodiment of the present invention.
- FIG. 16 is a sectional view of another example of the bearing mechanism according to a preferred embodiment of the present invention.
- FIG. 17 is a sectional view of a further example of the bearing mechanism according to a preferred embodiment of the present invention.
- FIG. 18 is a sectional view of a still further example of the bearing mechanism according to a preferred embodiment of the present invention.
- the upper side of a motor in a center axis direction will be just referred to as “upper” and the lower side as “lower”.
- the up-and-down direction is not intended to indicate the positional relationship or the orientation when the motor is installed within an actual device.
- the direction parallel or substantially parallel to the center axis will be referred to as “axial”.
- the radial direction about the center axis will be just referred to as “radial”.
- the circumferential direction about the center axis will be just referred to as “circumferential”.
- FIG. 1 is a vertical sectional view of a disk drive apparatus 1 including a spindle motor (hereinafter just referred to as “motor”) according to one illustrative preferred embodiment of the present invention.
- the disk drive apparatus 1 is preferably a so-called hard disk drive apparatus.
- the disk drive apparatus 1 preferably includes, e.g., three disks 11 , a motor 12 , an access unit 13 , and a housing 14 .
- the motor 12 is configured to rotate the disks 11 .
- the access unit 13 performs at least one of information reading and writing tasks with respect to the disks 11 .
- the housing 14 preferably includes an open-top box-shaped first housing member 141 and a flat second housing member 142 .
- the second housing member 142 is fitted to the first housing member 141 so as to define the housing 14 .
- the disks 11 , the motor 12 and the access unit 13 are accommodated within the housing 14 .
- the internal space of the disk drive apparatus 1 is a clean space in which dust is not present or is extremely rare.
- air is filled into the disk drive apparatus 1 .
- helium gas, hydrogen gas, etc. may be filled into the disk drive apparatus 1 .
- a mixture of air and helium gas or air and hydrogen gas may be filled into the disk drive apparatus 1 .
- the three disks 11 are fixed to a rotor hub of the motor 12 at a regular or substantially regular interval along the direction of a center axis J 1 by virtue of a clamper 151 and spacers 152 .
- the access unit 13 preferably includes six heads 131 , six arms 132 , and a head moving mechanism 133 .
- the heads 131 come close to the disks 11 and magnetically perform at least one of information reading and writing tasks.
- the arms 132 are configured to support the heads 131 .
- the head moving mechanism 133 is configured to move the arms 132 so as to move the heads 131 relative to the disks 11 . With this configuration, the heads 131 come close to the rotating disks 11 and gain access to desired positions of the disks 11 .
- the number of the disks 11 is not limited to three but may be one, two, or more than three, for example.
- FIG. 2 is a vertical sectional view of the motor 12 in accordance with a preferred embodiment of the present invention.
- the motor 12 is preferably an outer rotor type motor.
- the motor 12 preferably includes a stationary unit 2 as a fixed assembly, a rotary unit 3 as a rotating assembly, and a bearing mechanism 4 .
- the rotary unit 3 is rotatably supported by the bearing mechanism to rotate about the center axis J 1 with respect to the stationary unit 2 .
- the stationary unit 2 preferably includes a base plate 21 as a base portion and a stator 22 .
- the base plate 21 and the first housing member 141 shown in FIG. 1 are preferably provided by a single monolithic member.
- the base plate 21 is a portion of the housing 14 .
- the stator 22 is fixed around a cylindrical holder 211 of the base plate 21 .
- the bearing mechanism 4 is fixed to a hole portion provided inside the holder 211 .
- the base plate 21 and the first housing member 141 may be defined by different members.
- the rotary unit 3 preferably includes a rotor hub 31 and a rotor magnet 32 .
- the rotor hub 31 preferably includes a cover portion 311 and a cylinder portion 312 .
- the cover portion 311 extends radially outward from the upper portion of the bearing mechanism 4 .
- the cylinder portion 312 extends downward from an outer edge portion of the cover portion 311 .
- the rotor magnet 32 is fixed to an inner surface of the cylinder portion 312 .
- the rotor magnet 32 is radially opposed to the stator 22 . Torque is generated between the stator 22 and the rotor magnet 32 .
- the magnetic center of the stator 22 is positioned below the magnetic center of the rotor magnet 32 .
- a magnetic action which attracts the rotor magnet 32 downward is generated between the rotor magnet 32 and the stator 22 .
- the cover portion 311 preferably includes holes 314 used in fixing a clamper 151 arranged to clamp the disks 11 shown in FIG. 1 .
- the holes 314 are positioned above the stator 22 and are arranged to extend through the cover portion 311 in the up-and-down direction.
- fasteners 153 such as, for example, screws are inserted into the through-holes of the clamper 151 and the holes 314 of the cover portion 311 .
- the clamper 151 is fixed to the upper surface of the cover portion 311 .
- FIG. 3 is an enlarged sectional view of the bearing mechanism 4 .
- the bearing mechanism 4 preferably includes a shaft portion 41 , a lower opposing portion 42 , an upper opposing portion 43 , a lower outer ring-shaped portion 44 , a sleeve portion 45 , a cap 46 , and a lubricant 47 .
- the shaft portion 41 , the lower opposing portion 42 , the upper opposing portion 43 , and the lower outer ring-shaped portion 44 may be regarded as portions of the stationary unit 2 .
- the sleeve portion 45 and the cap 46 may be regarded as portions of the rotary unit 3 .
- the shaft portion 41 preferably includes a cylindrical outer circumferential surface.
- the shaft portion 41 is preferably, for example, press-fitted to the hole portion defined inside the lower opposing portion 42 and is arranged to extend along the center axis J 1 in the up-and-down direction.
- the shaft portion 41 is preferably made of, e.g., stainless steel.
- a hole 412 is preferably provided in the upper portion of the shaft portion 41 .
- the second housing member 142 is fixed to the motor 12 by inserting a fastener 154 , such as, for example, a screw, into the central through-hole of the second housing member 142 and the hole 412 of the shaft portion 41 as shown in FIG. 1 .
- the lower opposing portion 42 is preferably made of, e.g., copper or high-tension brass.
- the lower opposing portion 42 extends radially outward from the lower portion of the shaft portion 41 .
- the upper surface of the lower opposing portion 42 is axially opposed to the lower end surface of the sleeve portion 45 .
- the lower outer ring-shaped portion 44 is fixed relative to the lower opposing portion 42 .
- the lower outer ring-shaped portion 44 extends upward from the outer edge portion of the lower opposing portion 42 .
- the lower outer ring-shaped portion 44 is positioned outside the outer circumferential surface of the sleeve portion 45 .
- the inner circumferential surface of the lower outer ring-shaped portion 44 has a cylindrical or substantially cylindrical shape and surrounds at least a portion of the outer circumferential surface of the sleeve portion 45 .
- the upper opposing portion 43 extends radially outward from the upper portion of the shaft portion 41 at the upper side of the sleeve portion 45 .
- the lower surface of the upper opposing portion 43 is axially opposed to the upper end surface of the sleeve portion 45 .
- the cap 46 is fixed to the upper end of the sleeve portion 45 .
- the cap 46 is positioned above the upper opposing portion 43 .
- the shaft portion 41 is arranged inside the sleeve portion 45 .
- the sleeve portion 45 is supported by the shaft portion 41 to rotate about the center axis J 1 .
- the sleeve portion 45 preferably includes a sleeve body 451 , a lower thrust plate 452 , an upper thrust plate 453 , and a flange portion 454 .
- the sleeve body 451 is preferably made of, e.g., stainless steel, aluminum, copper, etc.
- the sleeve body 451 preferably includes a through-hole arranged to accommodate the shaft portion 41 .
- the sleeve body 451 preferably includes a vertical communication path 541 extending in the up-and-down direction, which serves as a first communication path.
- the sleeve body 451 is positioned between the outer circumferential surface of the shaft portion 41 and the inner circumferential surface of the lower outer ring-shaped portion 44 .
- the flange portion 454 protrudes radially outward from the upper portion of the sleeve body 451 .
- the flange portion 454 is preferably connected to the cover portion 311 shown in FIG. 2 .
- the flange portion 454 may be provided independently of the sleeve body 451 .
- the cover portion 311 may be provided independently of the flange portion 454 .
- the cap 46 has a flat or substantially flat annular shape.
- the outer peripheral portion of the cap 46 is fixed to the upper portion of the flange portion 454 .
- the inner peripheral portion of the cap 46 is positioned above the upper opposing portion 43 .
- the inner peripheral end portion of the cap is bent downward.
- the upper portion of the upper opposing portion 43 preferably includes an annular recess portion 431 depressed downward.
- the lower end of the inner peripheral end portion of the cap 46 is positioned within the recess portion 431 .
- the lower thrust plate 452 has an annular shape.
- the lower thrust plate 452 is fixed to the lower portion of the sleeve body 451 .
- the lower surface of the lower thrust plate 452 serves as the lower surface of the sleeve portion 45 .
- a lower horizontal communication path 542 serving as a second communication path is defined between the sleeve body 451 and the lower thrust plate 452 .
- the lower horizontal communication path 542 extends from the lower end of the vertical communication path 541 to the outer circumferential surface of the sleeve portion 45 .
- the lower horizontal communication path 542 can be easily defined by the lower thrust plate 452 .
- the upper thrust plate 453 has an annular shape.
- the upper thrust plate 453 is fixed to the upper portion of the sleeve body 451 .
- the upper surface of the upper thrust plate 453 serves as the upper surface of the sleeve portion 45 .
- An upper horizontal communication path 543 serving as a third communication path is defined between the sleeve body 451 and the upper thrust plate 453 .
- the upper horizontal communication path 543 extends from the upper end of the vertical communication path 541 to the outer circumferential surface of the sleeve portion 45 .
- the upper horizontal communication path 543 can be easily defined by the upper thrust plate 453 .
- the sleeve portion 45 preferably includes communication paths which include the vertical communication path 541 , the lower horizontal communication path 542 and the upper horizontal communication path 543 .
- FIG. 4 is a sectional view of the sleeve body 451 , which additionally shows those portions lying more inward.
- Dynamic pressure grooves are preferably arranged on the inner circumferential surface of the sleeve body 451 , namely on the inner circumferential surface of the sleeve portion 45 . Consequently, as shown in FIG. 3 , a radial dynamic-pressure bearing portion 51 a is provided in a radial gap 51 between the outer circumferential surface of the shaft portion 41 and the inner circumferential surface of the sleeve portion 45 .
- the radial dynamic-pressure bearing portion 51 a preferably includes an upper radial dynamic-pressure bearing portion 511 and a lower radial dynamic-pressure bearing portion 512 .
- the upper radial dynamic-pressure bearing portion 511 preferably includes a herringbone-shaped upper radial dynamic-pressure groove array 611 .
- the lower radial dynamic-pressure bearing portion 512 preferably includes a herringbone-shaped lower radial dynamic-pressure groove array 612 .
- the axial length of an upper herringbone region is preferably larger than the axial length of a lower herringbone region.
- the axial length of an upper herringbone region is preferably equal or substantially equal to the axial length of a lower herringbone region.
- FIG. 5 is a plan view of the lower opposing portion 42 according to a preferred embodiment of the present invention.
- a spiral lower thrust dynamic-pressure groove array 621 serving as a dynamic pressure generating groove array is arranged on the upper surface of the lower opposing portion 42 .
- a lower thrust dynamic-pressure bearing portion 52 a is defined in a lower thrust gap 52 between the lower surface of the sleeve portion 45 and the upper surface of the lower opposing portion 42 .
- the upper surface of the lower opposing portion is axially opposed to the lower end surface of the sleeve portion 45 through the lower thrust gap 52 .
- FIG. 6 is a plan view of the upper thrust plate 453 .
- a spiral upper thrust dynamic-pressure groove array 622 serving as a dynamic pressure generating groove array is preferably arranged on the upper surface of the upper thrust plate 453 .
- an upper thrust dynamic-pressure bearing portion 53 a is defined in an upper thrust gap 53 between the upper end surface of the sleeve portion 45 and the lower surface of the upper opposing portion 43 .
- the lower surface of the upper opposing portion 43 is axially opposed to the upper end surface of the sleeve portion 45 through the upper thrust gap 53 .
- a lower seal portion 56 a is preferably defined in a lower seal gap between the outer circumferential surface of the sleeve portion 45 and the inner circumferential surface of the lower outer ring-shaped portion 44 .
- the upper surface of the upper thrust plate 453 preferably includes a thrust dynamic-pressure groove array
- the lower surface of the lower thrust plate 452 preferably does not include a thrust dynamic-pressure groove array.
- FIG. 7 is an enlarged sectional view showing the lower horizontal communication path 542 and its vicinity.
- FIG. 8 is a plan view of the lower thrust plate 452 .
- the upper surface of the lower thrust plate 452 preferably includes a height variation portion 641 .
- the height variation portion 641 is preferably provided in the entire periphery of the upper surface of the lower thrust plate 452 .
- the radial outer region of the height variation portion 641 is positioned axially below the radial inner region of the height variation portion 641 .
- the radial outer region of the height variation portion 641 defines the lower horizontal communication path 542 in cooperation with the lower portion of the sleeve body 451 .
- the upper surface of the lower thrust plate 452 preferably includes a plurality of radially-extending adhesive agent grooves 642 arranged radially inward of the height variation portion 641 .
- the sleeve body 451 preferably includes a lower annular surface 461 radially extending about the center axis J 1 and opposed to the upper surface of the lower thrust plate 452 .
- the lower annular surface 461 is a portion of the lower surface of the sleeve body 451 .
- the vertical communication path 541 preferably includes a lower opening portion 544 opened on the lower annular surface 461 . At least a portion of the radial outer region of the height variation portion 641 of the lower thrust plate 452 shown in FIG. 8 is axially opposed to the lower opening portion 544 .
- the lower inner peripheral portion of the sleeve body 451 preferably includes a lower protrusion portion 456 protruding downward.
- the lower protrusion portion 456 is inserted into the lower thrust plate 452 .
- the outer diameter of the lower thrust plate 452 is smaller than the outer diameter of the lower portion of the sleeve body 451 .
- the sleeve body 451 preferably includes a large-diameter portion arranged in the lower portion thereof.
- the lower thrust plate 452 serves as a small-diameter portion.
- the lower portion of the sleeve portion 45 preferably includes a large-diameter portion and a small-diameter portion positioned below the large-diameter portion and having a diameter smaller than the diameter of the large-diameter portion.
- the outer peripheral portion of the lower opposing portion 42 preferably includes an outer periphery protrusion portion 421 protruding upward.
- the outer periphery protrusion portion 421 is positioned inside the lower outer ring-shaped portion 44 .
- the outer periphery protrusion portion 421 is positioned radially outward of the lower thrust plate 452 .
- the outer periphery protrusion portion 421 is radially opposed to the outer circumferential surface of the small-diameter portion of the sleeve portion 45 .
- An axially-extending vertical gap 551 is defined between the outer circumferential surface of the lower thrust plate 452 and the inner circumferential surface of the outer periphery protrusion portion 421 .
- the upper end of the vertical gap 551 is connected to the outer peripheral portion of the lower horizontal communication path 542 .
- the lower end of the vertical gap 551 is connected to the outer peripheral portion of the lower thrust gap 52 .
- the outer periphery protrusion portion 421 is axially opposed to the lower portion of the sleeve body 451 .
- the upper surface of the outer periphery protrusion portion 421 is axially opposed to the lower surface of the large-diameter portion of the sleeve portion 45 .
- a horizontal gap 552 is defined between the upper surface of the outer periphery protrusion portion 421 and the lower annular surface 461 of the sleeve body 451 .
- the horizontal gap 552 extends in the radial direction.
- the inner peripheral portion of the horizontal gap 552 is connected to the outer peripheral portion of the lower horizontal communication path 542 .
- the outer peripheral portion of the horizontal gap 552 is connected to the lower end of the lower seal gap 56 .
- the lower horizontal communication path 542 defined by the lower thrust plate 452 essentially interconnects the lower opening portion 544 of the vertical communication path 541 and the lower seal gap 56 .
- the horizontal gap 552 can be regarded as a portion of the lower seal portion 56 a.
- the lower opening portion 544 of the vertical communication path 541 axially overlaps with the lower thrust dynamic-pressure bearing portion 52 a. This makes it possible to easily increase the size of the lower thrust dynamic-pressure bearing portion 52 a. As a result, it is possible to easily obtain a large enough levitation force required for the lower thrust dynamic-pressure bearing portion 52 a to lift the rotary unit 3 .
- the lower seal portion 56 a serves as a pumping seal portion and preferably includes a pumping section 561 and a buffer section 562 .
- the lower end of the pumping section 561 is connected to the outer peripheral portion of the horizontal gap 552 .
- the buffer section 562 is positioned above the pumping section 561 and is connected to the upper end of the pumping section 561 .
- the lower seal gap 56 has a cylindrical or substantially cylindrical shape.
- spiral grooves are arranged on the inner circumferential surface of the lower outer ring-shaped portion 44 .
- a force which pushes the lubricant 47 downward is generated by the rotation of the sleeve portion 45 .
- the outer circumferential surface of the sleeve portion 45 is inclined radially inward and upward.
- the radial width of the lower seal gap 56 is gradually increased upward.
- a boundary surface of the lubricant 47 is preferably arranged in the buffer section 562 .
- the lubricant 47 flows from the buffer section 562 toward the pumping section 561 .
- the boundary surface of the lubricant 47 moves downward.
- the boundary surface may be positioned within the pumping section 561 .
- FIG. 9 is an enlarged sectional view showing the upper horizontal communication path 543 and its vicinity.
- the lower surface of the upper thrust plate 453 preferably has substantially the same shape as the plan-view shape of the lower thrust plate 452 shown in FIG. 8 .
- the lower surface of the upper thrust plate 453 preferably includes a height variation portion.
- the height variation portion is preferably provided on the entire periphery of the lower surface of the upper thrust plate 453 .
- the radial outer region of the height variation portion is positioned axially above the radial inner region of the height variation portion.
- the radial outer region of the height variation portion defines the upper horizontal communication path 543 in cooperation with the upper portion of the sleeve body 451 .
- the height variation portion is provided in the entire periphery of the lower surface of the upper thrust plate 453 , it becomes possible to attach the upper thrust plate 453 to the sleeve body 451 without having to give consideration to the orientation of the upper thrust plate 453 .
- a plurality of radially-extending adhesive agent grooves is arranged radially inward of the height variation portion.
- the sleeve body 451 preferably includes an upper annular surface 462 radially extending about the center axis J 1 and opposed to the lower surface of the upper thrust plate 453 .
- the upper annular surface 462 is a portion of the upper surface of the sleeve body 451 .
- the vertical communication path 541 preferably includes an upper opening portion 545 opened on the upper annular surface 462 . At least a portion of the radial outer region of the height variation portion of the upper thrust plate 453 is axially opposed to the upper opening portion 545 .
- the upper inner peripheral portion of the sleeve body 451 preferably includes an upper protrusion portion 459 protruding upward.
- the upper protrusion portion 459 is inserted into the upper thrust plate 453 .
- the upper end of the upper protrusion portion 459 is positioned axially above the upper surface of the upper thrust plate 453 .
- a portion of the radial dynamic-pressure bearing portion 51 a radially overlaps with the upper thrust plate 453 .
- the radial dynamic-pressure bearing portion 51 a can be positioned upward by providing the upper protrusion portion 459 .
- the center of the rotary unit 3 and the center of the radial dynamic-pressure bearing portion 51 a can be caused to come close to each other. This makes it possible to significantly reduce and prevent vibration.
- the upper opening portion 545 axially overlaps with the upper thrust dynamic-pressure bearing portion 53 a. This makes it possible to increase the size of the upper thrust dynamic-pressure bearing portion 53 a.
- the inner peripheral portion of the flange portion 454 protrudes upward from the outer peripheral portion of the sleeve body 451 and surrounds the radial outer surface of the upper opposing portion 43 .
- the cylindrical or substantially cylindrical inner circumferential surface of the flange portion 454 surrounds at least a portion of the outer circumferential surface of the upper opposing portion 43 at the radial outer side.
- the inner circumferential surface of the flange portion 454 is radially opposed to the outer circumferential surface of the upper thrust plate 453 .
- the inner peripheral portion of the flange portion 454 will be referred to as “upper outer ring-shaped portion 455 ”.
- the upper outer ring-shaped portion 455 is a portion whose relative position is fixed with respect to the sleeve portion 45 .
- An upper seal gap 57 is defined between the inner circumferential surface of the upper outer ring-shaped portion 455 and the outer circumferential surface of the upper opposing portion 43 .
- the upper horizontal communication path 543 interconnects the upper opening portion 545 and the upper seal gap 57 .
- the upper seal gap 57 defines an upper seal portion 57 a.
- An axially-extending vertical gap 553 is defined between the outer circumferential surface of the upper thrust plate 453 and the inner circumferential surface of the upper outer ring-shaped portion 455 .
- the upper end of the vertical gap 553 is joined to the lower end of the upper seal gap 57 and the outer peripheral portion of the upper thrust gap 53 .
- the upper seal gap 57 is joined to the upper thrust gap 53 .
- the lower end of the vertical gap 553 is connected to the outer peripheral portion of the upper horizontal communication path 543 .
- the radial width of the upper seal gap 57 is increased upward.
- the outer circumferential surface of the upper opposing portion 43 is preferably inclined radially inward and upward.
- the inner circumferential surface of the upper outer ring-shaped portion 455 is inclined radially inward and upward. In this manner, the upper seal portion 57 a is inclined radially inward and upward. Accordingly, any air bubbles existing within the lubricant 47 can be efficiently discharged through the use of centrifugal forces acting on the lubricant 47 .
- a circulation path 50 mainly defined by the lower thrust gap 52 , the radial gap 51 , the upper thrust gap 53 , the vertical gap 553 , the upper horizontal communication path 543 , the vertical communication path 541 , the lower horizontal communication path 542 and the vertical gap 551 .
- the circulation path 50 is filled with the lubricant 47 .
- the circulation path 50 and the lower seal gap 56 communicate with each other.
- the circulation path 50 and the upper seal gap 57 communicate with each other.
- the lubricant 47 is filled over a range extending from the circulation path 50 to the lower seal gap 56 and is also filled over a range extending from the circulation path 50 to the upper seal gap 57 .
- the horizontal gap 552 extending from the radial outer opening of the lower horizontal communication path 542 to the lower seal gap 56 is preferably filled with the lubricant 47 .
- the vertical gap 553 extending from the radial outer opening of the upper horizontal communication path 543 to the upper seal gap 57 is also filled with the lubricant 47 .
- the motor 12 is provided with the lower thrust plate 452 and the upper thrust plate 453 , it is possible to increase the load capacity and to reduce the levitation start revolution number. Inasmuch as the sliding contact time in the thrust bearing becomes shorter during the startup and stop operations, it is possible to prolong the lifespan of the motor 12 . By enhancing the thrust bearing performance, it is possible to increase the shaft diameter and to reduce the bearing attenuation. This makes it possible to significantly reduce and prevent the vibration response at a high frequency.
- the lower thrust plate 452 and the upper thrust plate 453 are preferably manufactured by, for example, pressing, cutting, etc.
- the lower thrust plate 452 and the upper thrust plate 453 may be made of a solid material or a sintered material.
- the axial length of the upper herringbone region is preferably larger than the axial length of the lower herringbone region.
- the axial length of the upper herringbone region is preferably equal or substantially equal to the axial length of the lower herringbone region.
- FIG. 10 is a schematic diagram showing the lower thrust plate 452 and its vicinity.
- the cross section is not hatched.
- the lubricant 47 is preferably injected from the upper seal gap 57 .
- the sleeve body 451 and the flange portion 454 are preferably formed as a single monolithic member. For that reason, it is almost impossible to inject the lubricant 47 from the lower seal gap 56 .
- the lower surface of the lower thrust plate 452 makes contact with the upper surface of the lower opposing portion 42 in the axial direction.
- the horizontal opening portion 546 is preferably opened in a border between the lower portion of the sleeve body 451 and the lower thrust plate 452 , namely a border between the large-diameter portion and the small-diameter portion.
- the horizontal opening portion 546 is positioned on the outer circumferential surface of the lower thrust plate 452 .
- the outer periphery protrusion portion 421 is arranged to protrude toward the horizontal opening portion 546 such that the lubricant 47 reaching the horizontal opening portion 546 comes into contact with the outer periphery protrusion portion 421 . This makes it possible to easily guide the lubricant 47 to the vertical gap 551 , the horizontal gap 552 , and the lower seal gap 56 .
- the minimum radial width 72 between the outer circumferential surface of the lower thrust plate 452 and the inner circumferential surface of the outer periphery protrusion portion 421 and the minimum axial width 73 between the lower surface of the lower portion of the sleeve body 451 and the upper surface of the outer periphery protrusion portion 421 is preferably equal to or smaller than the axial width 71 of the radial outer opening of the lower horizontal communication path 542 .
- the upper surface of the region of the lower thrust plate 452 arranged radially outward of the height variation portion 641 is preferably positioned below the upper surface of the outer periphery protrusion portion 421 . More preferably, on the cross section including the center axis J 1 , the straight line 76 interconnecting the outer edge of the lower surface of the lower thrust plate 452 and the outer edge of the lower surface of the lower portion of the sleeve body 451 extends across the outer periphery protrusion portion 421 . This preferably makes it possible to fill the lubricant 47 with ease.
- the “outer edge of the lower surface” preferably does not include any chamfered portion.
- the structure mentioned just above is especially suitable in a case where the upper portion of the outer peripheral portion of the sleeve portion 45 extends radially outward of the lower seal portion 56 a and in a case where the lubricant 47 cannot be virtually injected from the lower seal portion 56 a.
- FIG. 11 is a schematic diagram showing the lower thrust plate 452 in accordance with a preferred embodiment of the present invention and its vicinity.
- the lower thrust plate 452 is preferably bonded to the sleeve body 451 by an adhesive agent 78 .
- Use of the adhesive agent 78 makes it possible to fit the lower thrust plate 452 to the lower protrusion portion 456 in a running fit state. This makes it possible to prevent deformation of the lower thrust plate 452 which would be caused by, for example, press fitting.
- the adhesive agent 78 is applied on the lower surface of the sleeve body 451 or the upper surface of the lower thrust plate 452 . Then, the lower thrust plate 452 is attached to the sleeve body 451 .
- the adhesive agent 78 is arranged in at least a portion of the inner surface of each of the adhesive agent grooves 642 of the lower thrust plate 452 .
- the adhesive agent 78 is, for example, a thermosetting adhesive agent whose viscosity is decreased prior to occurrence of hardening caused by heating.
- the adhesive agent 78 is slightly extruded from the radial outer end portions of the adhesive agent grooves 642 .
- the height variation portion 641 of the lower thrust plate 452 preferably includes a height variation surface 640 inclined radially inward and upward. The adhesive agent 78 extruded radially outward from the adhesive agent grooves 642 is held between the height variation surface 640 and the lower annular surface 461 of the sleeve body 451 .
- the adhesive agent 78 extruded radially inward from the adhesive agent grooves 642 is preferably provided between the outer circumferential surface 458 of the lower protrusion portion 456 and the inner circumferential surface 644 of the lower thrust plate 452 .
- the gap defined between the outer circumferential surface 458 of the lower protrusion portion 456 and the inner circumferential surface 644 of the lower thrust plate 452 will be referred to as “vertical adhesive agent gap 781 ”.
- the lower portion of the outer circumferential surface 458 is preferably a slant surface inclined radially inward and downward.
- the adhesive agent 78 is held stably.
- the lower portion of the vertical adhesive agent gap 781 preferably includes an adhesive agent holding gap 782 whose radial width is gradually increased downward.
- the inner circumferential surface 644 of the lower thrust plate 452 may be inclined radially outward and downward.
- the outer circumferential surface 458 of the lower protrusion portion 456 is inclined radially inward and downward and the inner circumferential surface 644 of the lower thrust plate 452 is parallel or substantially parallel to the center axis J 1 or inclined radially outward and downward.
- the angle between the outer circumferential surface 458 of the lower protrusion portion 456 and the center axis J 1 is larger than the angle between the inner circumferential surface 644 of the lower thrust plate 452 and the center axis J 1 . This makes it possible to easily secure the size of the lower thrust dynamic-pressure bearing portion 52 a while providing the adhesive agent holding gap 782 .
- the axial depth 74 of the adhesive agent grooves 642 is preferably smaller than the axial width 71 of the lower horizontal communication path 542 .
- the minimum radial width 75 of the vertical adhesive agent gap 781 is also preferably smaller than the axial width 71 .
- FIG. 13 is a plan view showing another example of the lower thrust plate 452 in accordance with a preferred embodiment of the present invention.
- the height variation portion 641 is provided in only a portion of the lower thrust plate 452 along the circumferential direction. In other words, only a portion of the outer edge portion of the lower thrust plate 452 along the circumferential direction is depressed downward.
- Other configurations of the lower thrust plate 452 shown in FIG. 13 remain the same as those of the lower thrust plate 452 shown in FIG. 8 .
- the lower thrust plate 452 is preferably attached to the lower portion of the sleeve body 451 in such a fashion that the radial outer region of the height variation portion 641 overlaps with the lower opening portion 544 of the vertical communication path 541 .
- FIG. 14 is a sectional view showing a further example of the lower thrust plate 452 in accordance with a preferred embodiment of the present invention.
- the upper surface of the lower thrust plate 452 shown in FIG. 14 preferably includes a height variation portion 643 .
- the radial inner region of the height variation portion 643 is positioned axially below the radial outer region thereof. At least a portion of the radial inner region of the height variation portion 643 axially overlaps with the lower opening portion 544 of the vertical communication path 541 .
- the upper surface of the lower thrust plate 452 preferably includes a groove 646 extending from the height variation portion 643 to the outer circumferential surface of the lower thrust plate 452 .
- a lower horizontal communication path 542 is preferably defined by the lower surface of the sleeve body 451 and the groove 646 .
- the gap between the outer circumferential surface of the lower protrusion portion 456 of the sleeve body 451 and the inner circumferential surface of the lower thrust plate 452 is preferably sealed by the adhesive agent 78 .
- a depression portion positioned axially below the remaining portion on the upper surface of the lower thrust plate 452 may be provided in many different shapes and arrangements as long as the depression portion overlaps with the lower opening of the vertical communication path 541 .
- a depression portion may be provided at the radial center of the lower thrust plate 452 .
- a lower horizontal communication path 542 can be provided in the sleeve portion 45 by providing a recess portion, such as, for example, a groove or the like, which extends from the depression portion to the outer circumferential surface of the lower thrust plate 452 .
- FIG. 15 is a view showing a still further example of the lower thrust plate 452 and the sleeve body 451 .
- the lower surface of the sleeve body 451 preferably includes a height variation portion 645 .
- the radial outer region of the height variation portion 645 is preferably positioned axially above the radial inner area thereof.
- the height variation portion 645 may be provided only in the vicinity of the lower opening of the vertical communication path 541 or may be provided in the entire periphery of the lower surface of the sleeve body 451 .
- the upper surface of the lower thrust plate 452 is planar.
- a radially-extending adhesive agent groove may be provided on the upper surface of the lower thrust plate 452 .
- a radially-extending lower horizontal communication path 542 is defined between the radial outer region of the height variation portion 645 and the upper surface of the lower thrust plate 452 .
- FIG. 15 it is possible to easily provide the lower horizontal communication path 542 . It is also possible to simplify the shape of the lower thrust plate 452 .
- FIG. 16 is a view showing another example of the bearing mechanism 4 of a preferred embodiment of the present invention.
- the bearing mechanism 4 shown in FIG. 16 is not provided with an upper thrust dynamic-pressure bearing portion.
- the vertical communication path 541 is preferably inclined radially inward and upward.
- the upper surface of the sleeve body 451 is opposed to the lower surface of the upper opposing portion 43 .
- the gap defined between the upper surface of the sleeve body 451 and the lower surface of the upper opposing portion 43 will be referred to as “upper thrust gap 58 ”.
- the lower surface of the upper opposing portion is axially opposed to the upper end surface of the sleeve portion 45 through the upper thrust gap 58 .
- the upper thrust gap 58 preferably only serves as a gap and does not define up an upper thrust dynamic-pressure bearing portion.
- the upper opening of the vertical communication path 541 axially overlaps with the lower surface of the upper opposing portion 43 .
- An upper seal gap 57 is defined between the outer circumferential surface of the upper opposing portion 43 and the inner circumferential surface of the upper outer ring-shaped portion 455 .
- a lubricant 47 is held within the upper seal gap 57 so as to define an upper seal portion 57 a.
- the upper seal portion 57 a is inclined radially inward and upward. Thus, air bubbles existing within the lubricant 47 are efficiently discharged from the upper seal portion 57 a.
- the vertical communication path 541 is substantially joined to the upper seal gap 57 .
- a magnetically-generated downward force acts on the sleeve portion 45 .
- the sleeve portion 45 is preferably axially supported by only the lower thrust dynamic-pressure bearing portion 52 a.
- a circulation path 50 mainly defined by the lower thrust gap 52 , the radial gap 51 , the upper thrust gap 58 , the vertical communication path 541 , the lower horizontal communication path 542 , and the vertical gap 551 .
- the circulation path 50 is filled with the lubricant 47 .
- the circulation path 50 and the upper seal gap 57 communicate with each other.
- the circulation path 50 and the upper seal gap 57 are filled with the lubricant 47 .
- the outer peripheral portion of the upper thrust gap 58 communicates with the upper seal gap 57 .
- the lubricant 47 flows downward along the radial gap 51 during the rotation of the sleeve portion 45 .
- the structure near the lower thrust plate 452 and the filling method of the lubricant 47 preferably remain the same as those shown in FIG. 3 or described in other examples. Accordingly, it is possible to fill the lubricant 47 with ease.
- FIG. 17 is a view showing a further example of the bearing mechanism 4 according to a preferred embodiment of the present invention.
- the bearing mechanism 4 shown in FIG. 17 is preferably not provided with the lower thrust plate 452 and the upper thrust plate 453 shown in FIG. 3 .
- the portions corresponding to the lower portion of the sleeve body 451 and the lower thrust plate 452 shown in FIG. 3 are preferably continuously integrated with each other as a single monolithic member.
- the portions corresponding to the upper portion of the sleeve body 451 and the upper thrust plate 453 shown in FIG. 3 are also continuously integrated with each other as a single monolithic member.
- the sleeve portion 45 including the portions corresponding to the sleeve body 451 , the lower thrust plate 452 , the upper thrust plate 453 , and the flange portion 454 is preferably defined by an upper bearing member 481 including an upper radial dynamic-pressure groove array 611 and a lower bearing member 482 including a lower radial dynamic-pressure groove array 612 .
- the upper bearing member 481 is a member arranged near the upper radial dynamic-pressure groove array 611 .
- the lower bearing member 482 is a member corresponding to the lower portion of the sleeve body 451 , the outer peripheral portion of the upper portion of the sleeve body 451 and the flange portion 454 shown in FIG. 3 .
- Other configurations of the bearing mechanism 4 shown in FIG. 17 remain the same as those of the bearing mechanism 4 shown in FIG. 3 .
- the same configurations as those shown in FIG. 3 will be designated by like reference symbols.
- the sleeve portion 45 preferably includes a vertical communication path 541 as a first communication path, a lower horizontal communication path 542 as a second communication path, and an upper horizontal communication path 543 as a third communication path.
- the outer circumferential surface of the upper bearing member 481 axially overlaps with the vertical communication path 541 . This makes it possible to provide the vertical communication path 541 with ease.
- the lower horizontal communication path 542 and the upper horizontal communication path 543 may be provided only near the end portion of the vertical communication path 541 or may be provided in an annular shape over the entire periphery.
- the lower portion of the sleeve portion 45 preferably includes a large-diameter portion 651 and a small-diameter portion 652 .
- the small-diameter portion 652 is smaller in diameter than the large-diameter portion 651 .
- the small-diameter portion 652 is the lowermost portion of the sleeve portion 45 and is positioned below the large-diameter portion 651 .
- the lower opposing portion 42 preferably includes an outer periphery protrusion portion 421 .
- a structure not provided with any thrust plate may be applied to the bearing mechanism 4 shown in FIG. 16 .
- the sleeve body 451 and the lower thrust plate 452 shown in FIG. 16 are continuously defined with each other as a single monolithic member.
- Other configurations of the bearing mechanism 4 shown in FIG. 18 remain the same as those of the bearing mechanism 4 shown in FIG. 16 .
- the same configurations as those shown in FIG. 16 will be designated by like reference symbols.
- the sleeve portion 45 preferably includes a large-diameter portion 651 and a small-diameter portion 652 as in the bearing mechanism 4 shown in FIG. 17 .
- the lower opposing portion 42 preferably includes an outer periphery protrusion portion 421 . Accordingly, it is preferably possible to easily fill the lubricant 47 from the upper seal gap 57 .
- the radial dynamic-pressure groove array may be arranged on the outer circumferential surface of the shaft portion 41 .
- the lower thrust dynamic-pressure groove array 621 may be provided on the lower surface of the lower thrust plate 452 and the upper thrust dynamic-pressure groove array 622 may be provided on the lower surface of the upper opposing portion 43 .
- the lower thrust plate 452 and the upper thrust plate 453 may be attached to the sleeve body 451 preferably by, for example, press-fitting, press-fitting and bonding, welding, caulking, etc.
- the lower opening portion 544 need not be necessarily positioned in the border between the large-diameter portion 651 and the small-diameter portion 652 but may instead be positioned near the border.
- the motor 12 may be an inner rotor type motor.
- the motor 12 can be used in a disk drive apparatus other than the hard disk drive apparatus, e.g., an optical disk drive apparatus.
- the motor 12 can be used in other applications than the disk drive apparatus.
- the motor 12 can be used as a polygon scanner motor in a laser beam printer, a color wheel driving motor in a projector, etc.
- the preferred embodiments of the present invention are applicable to a bearing mechanism for motors having different purposes.
- the preferred embodiments of the present invention can be applied to a bearing mechanism for other applications than motors.
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- Engineering & Computer Science (AREA)
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- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Sliding-Contact Bearings (AREA)
- Rotational Drive Of Disk (AREA)
- Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)
- Sealing Of Bearings (AREA)
Abstract
Description
- 1. Field of the Invention
- The present invention relates to a bearing mechanism, and more specifically to a bearing mechanism for use in a motor.
- 2. Description of the Related Art
- Conventionally, a motor provided with a fluidic dynamic-pressure bearing mechanism has been used as a motor for a disk drive apparatus. For example, in a spindle motor disclosed in FIG. 1 of Japanese Patent Application Publication No. 2009-136143, a bottom plate 10, a first bearing component 16, a second bearing component 18n and a
fixed shaft 12 define a fixed component unit. Fluidic dynamic-pressure radial bearing units 22a and 22b are arranged between thefixed shaft 12 and arotor component 14. A fluidic dynamic-pressure thrust bearing unit 26 is arranged between the first bearing component 16 and therotor component 14. A pumping seal 36 is arranged between the second bearing component 18 and therotor component 14. Therotor component 14 is provided with a circulation path 28. The circulation path 28 interconnects a radial outer region of the thrust bearing unit 26 and a radial inner region of the pumping seal 36. A seal gap 34 is provided at the radial outer side of the thrust bearing unit 26. - In a case where a shaft is fixed, as in the spindle motor disclosed in Japanese Patent Application Publication No. 2009-136143, the upper side of a lower seal gap is covered with a rotor. This makes it impossible to fill a lubricant from the lower seal gap. However, if a lubricant is filled from an upper seal gap, the infiltration of the lubricant is stopped in an opening of a communication path. This may make it impossible to introduce the lubricant to the lower seal gap.
- Accordingly, a demand has existed for a bearing mechanism that makes it possible to easily fill a lubricant into the bearing mechanism from an upper seal gap.
- A bearing mechanism according to one illustrative preferred embodiment of the present invention includes a shaft portion, a sleeve portion, a lower opposing portion, a lower outer ring-shaped portion, and an upper opposing portion. The shaft portion is arranged about a center axis extending in an up-and-down direction. The shaft portion includes a cylindrical outer circumferential surface. The sleeve portion includes a through-hole arranged to accommodate the shaft portion. The sleeve portion is arranged to rotate about the center axis. The lower opposing portion extends radially outward from a lower portion of the shaft portion. The lower opposing portion includes an upper surface axially opposed to a lower end surface of the sleeve portion through a lower thrust gap. The lower outer ring-shaped portion includes a cylindrical or substantially cylindrical inner circumferential surface arranged to surround at least a portion of an outer circumferential surface of the sleeve portion. The relative position of the lower outer ring-shaped portion is fixed with respect to the lower opposing portion. The upper opposing portion extends radially outward from the shaft portion at an upper side of the sleeve portion. The upper opposing portion includes a lower surface axially opposed to an upper end surface of the sleeve portion through an upper thrust gap. A radial dynamic-pressure bearing portion is provided in a radial gap between the outer circumferential surface of the shaft portion and an inner circumferential surface of the sleeve portion. A lower thrust dynamic-pressure bearing portion is provided in the lower thrust gap. A lower seal portion is arranged in a lower seal gap between the outer circumferential surface of the sleeve portion and the inner circumferential surface of the lower outer ring-shaped portion. The lower seal portion is a pumping seal portion. An upper seal portion is arranged in an upper seal gap joined to the upper thrust gap. The sleeve portion includes a lower portion including a large-diameter portion and a small-diameter portion positioned below the large-diameter portion. The small-diameter portion is smaller in diameter than the large-diameter portion. The sleeve portion further includes a communication path joined to the upper seal gap. The communication path includes an opening portion opened in or near a border between the large-diameter portion and the small-diameter portion. The lower opposing portion includes an outer peripheral portion including an outer periphery protrusion portion radially opposed to an outer circumferential surface of the small-diameter portion and axially opposed to a lower surface of the large-diameter portion. A straight line interconnecting an outer edge of a lower surface of the small-diameter portion and an outer edge of the lower surface of the large-diameter portion on a cross section including the center axis extends across the outer periphery protrusion portion. A circulation path including the lower thrust gap, the radial gap, the upper thrust gap, and the communication pass communicates with the lower seal gap and the upper seal gap. A lubricant is filled in the circulation path, the lower seal gap and the upper seal gap.
- According to various preferred embodiments of the present invention, it is possible to easily fill the lubricant into the bearing mechanism from the upper seal gap.
- The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.
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FIG. 1 is a sectional view of a disk drive apparatus according to a preferred embodiment of the present invention. -
FIG. 2 is a sectional view of a motor according to a preferred embodiment of the present invention. -
FIG. 3 is a sectional view of a bearing mechanism according to a preferred embodiment of the present invention. -
FIG. 4 is a sectional view of a sleeve body according to a preferred embodiment of the present invention. -
FIG. 5 is a plan view of a lower opposing portion according to a preferred embodiment of the present invention. -
FIG. 6 is a plan view of an upper thrust plate according to a preferred embodiment of the present invention. -
FIG. 7 is an enlarged sectional view showing a lower horizontal communication path according to a preferred embodiment of the present invention and its vicinity. -
FIG. 8 is a plan view of a lower thrust plate according to a preferred embodiment of the present invention. -
FIG. 9 is an enlarged sectional view showing an upper horizontal communication path according to a preferred embodiment of the present invention and its vicinity. -
FIG. 10 is a schematic diagram showing a lower thrust plate according to a preferred embodiment of the present invention and its vicinity. -
FIG. 11 is a schematic diagram showing a lower thrust plate according to a preferred embodiment of the present invention and its vicinity. -
FIG. 12 is a schematic diagram showing a lower thrust plate according to a preferred embodiment of the present invention and its vicinity. -
FIG. 13 is a plan view of another example of the lower thrust plate according to a preferred embodiment of the present invention. -
FIG. 14 is a sectional view of a further example of the lower thrust plate according to a preferred embodiment of the present invention. -
FIG. 15 is a view showing a still further example of the lower thrust plate and the sleeve body according to a preferred embodiment of the present invention. -
FIG. 16 is a sectional view of another example of the bearing mechanism according to a preferred embodiment of the present invention. -
FIG. 17 is a sectional view of a further example of the bearing mechanism according to a preferred embodiment of the present invention. -
FIG. 18 is a sectional view of a still further example of the bearing mechanism according to a preferred embodiment of the present invention. - In the following description, the upper side of a motor in a center axis direction will be just referred to as “upper” and the lower side as “lower”. The up-and-down direction is not intended to indicate the positional relationship or the orientation when the motor is installed within an actual device. The direction parallel or substantially parallel to the center axis will be referred to as “axial”. The radial direction about the center axis will be just referred to as “radial”. The circumferential direction about the center axis will be just referred to as “circumferential”.
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FIG. 1 is a vertical sectional view of adisk drive apparatus 1 including a spindle motor (hereinafter just referred to as “motor”) according to one illustrative preferred embodiment of the present invention. Thedisk drive apparatus 1 is preferably a so-called hard disk drive apparatus. Thedisk drive apparatus 1 preferably includes, e.g., threedisks 11, amotor 12, anaccess unit 13, and ahousing 14. Themotor 12 is configured to rotate thedisks 11. Theaccess unit 13 performs at least one of information reading and writing tasks with respect to thedisks 11. - The
housing 14 preferably includes an open-top box-shapedfirst housing member 141 and a flatsecond housing member 142. Thesecond housing member 142 is fitted to thefirst housing member 141 so as to define thehousing 14. Thedisks 11, themotor 12 and theaccess unit 13 are accommodated within thehousing 14. Preferably, the internal space of thedisk drive apparatus 1 is a clean space in which dust is not present or is extremely rare. In the present preferred embodiment, air is filled into thedisk drive apparatus 1. Alternatively, helium gas, hydrogen gas, etc. may be filled into thedisk drive apparatus 1. Moreover, a mixture of air and helium gas or air and hydrogen gas may be filled into thedisk drive apparatus 1. - The three
disks 11 are fixed to a rotor hub of themotor 12 at a regular or substantially regular interval along the direction of a center axis J1 by virtue of aclamper 151 andspacers 152. Theaccess unit 13 preferably includes sixheads 131, sixarms 132, and ahead moving mechanism 133. Theheads 131 come close to thedisks 11 and magnetically perform at least one of information reading and writing tasks. Thearms 132 are configured to support theheads 131. Thehead moving mechanism 133 is configured to move thearms 132 so as to move theheads 131 relative to thedisks 11. With this configuration, theheads 131 come close to therotating disks 11 and gain access to desired positions of thedisks 11. The number of thedisks 11 is not limited to three but may be one, two, or more than three, for example. -
FIG. 2 is a vertical sectional view of themotor 12 in accordance with a preferred embodiment of the present invention. Themotor 12 is preferably an outer rotor type motor. Themotor 12 preferably includes astationary unit 2 as a fixed assembly, arotary unit 3 as a rotating assembly, and abearing mechanism 4. Therotary unit 3 is rotatably supported by the bearing mechanism to rotate about the center axis J1 with respect to thestationary unit 2. - The
stationary unit 2 preferably includes abase plate 21 as a base portion and astator 22. Thebase plate 21 and thefirst housing member 141 shown inFIG. 1 are preferably provided by a single monolithic member. Thebase plate 21 is a portion of thehousing 14. Thestator 22 is fixed around acylindrical holder 211 of thebase plate 21. Thebearing mechanism 4 is fixed to a hole portion provided inside theholder 211. Alternatively, thebase plate 21 and thefirst housing member 141 may be defined by different members. - The
rotary unit 3 preferably includes arotor hub 31 and arotor magnet 32. Therotor hub 31 preferably includes acover portion 311 and acylinder portion 312. Thecover portion 311 extends radially outward from the upper portion of thebearing mechanism 4. Thecylinder portion 312 extends downward from an outer edge portion of thecover portion 311. Therotor magnet 32 is fixed to an inner surface of thecylinder portion 312. Therotor magnet 32 is radially opposed to thestator 22. Torque is generated between thestator 22 and therotor magnet 32. - In the axial direction, the magnetic center of the
stator 22 is positioned below the magnetic center of therotor magnet 32. In themotor 12, a magnetic action which attracts therotor magnet 32 downward is generated between therotor magnet 32 and thestator 22. - The
cover portion 311 preferably includesholes 314 used in fixing aclamper 151 arranged to clamp thedisks 11 shown inFIG. 1 . Theholes 314 are positioned above thestator 22 and are arranged to extend through thecover portion 311 in the up-and-down direction. When theclamper 151 is attached to themotor 12,fasteners 153, such as, for example, screws are inserted into the through-holes of theclamper 151 and theholes 314 of thecover portion 311. Thus, theclamper 151 is fixed to the upper surface of thecover portion 311. -
FIG. 3 is an enlarged sectional view of thebearing mechanism 4. Thebearing mechanism 4 preferably includes ashaft portion 41, a lower opposingportion 42, an upper opposingportion 43, a lower outer ring-shapedportion 44, asleeve portion 45, acap 46, and alubricant 47. Theshaft portion 41, the lower opposingportion 42, the upper opposingportion 43, and the lower outer ring-shapedportion 44 may be regarded as portions of thestationary unit 2. Thesleeve portion 45 and thecap 46 may be regarded as portions of therotary unit 3. - The
shaft portion 41 preferably includes a cylindrical outer circumferential surface. Theshaft portion 41 is preferably, for example, press-fitted to the hole portion defined inside the lower opposingportion 42 and is arranged to extend along the center axis J1 in the up-and-down direction. Theshaft portion 41 is preferably made of, e.g., stainless steel. Ahole 412 is preferably provided in the upper portion of theshaft portion 41. Thesecond housing member 142 is fixed to themotor 12 by inserting afastener 154, such as, for example, a screw, into the central through-hole of thesecond housing member 142 and thehole 412 of theshaft portion 41 as shown inFIG. 1 . - The lower opposing
portion 42 is preferably made of, e.g., copper or high-tension brass. The lower opposingportion 42 extends radially outward from the lower portion of theshaft portion 41. The upper surface of the lower opposingportion 42 is axially opposed to the lower end surface of thesleeve portion 45. Accordingly, the lower outer ring-shapedportion 44 is fixed relative to the lower opposingportion 42. The lower outer ring-shapedportion 44 extends upward from the outer edge portion of the lower opposingportion 42. The lower outer ring-shapedportion 44 is positioned outside the outer circumferential surface of thesleeve portion 45. The inner circumferential surface of the lower outer ring-shapedportion 44 has a cylindrical or substantially cylindrical shape and surrounds at least a portion of the outer circumferential surface of thesleeve portion 45. The upper opposingportion 43 extends radially outward from the upper portion of theshaft portion 41 at the upper side of thesleeve portion 45. The lower surface of the upper opposingportion 43 is axially opposed to the upper end surface of thesleeve portion 45. Thecap 46 is fixed to the upper end of thesleeve portion 45. Thecap 46 is positioned above the upper opposingportion 43. - The
shaft portion 41 is arranged inside thesleeve portion 45. Thesleeve portion 45 is supported by theshaft portion 41 to rotate about the center axis J1. Thesleeve portion 45 preferably includes asleeve body 451, alower thrust plate 452, anupper thrust plate 453, and aflange portion 454. Thesleeve body 451 is preferably made of, e.g., stainless steel, aluminum, copper, etc. Thesleeve body 451 preferably includes a through-hole arranged to accommodate theshaft portion 41. Thesleeve body 451 preferably includes avertical communication path 541 extending in the up-and-down direction, which serves as a first communication path. Thesleeve body 451 is positioned between the outer circumferential surface of theshaft portion 41 and the inner circumferential surface of the lower outer ring-shapedportion 44. - The
flange portion 454 protrudes radially outward from the upper portion of thesleeve body 451. Theflange portion 454 is preferably connected to thecover portion 311 shown inFIG. 2 . Alternatively, theflange portion 454 may be provided independently of thesleeve body 451. Also, thecover portion 311 may be provided independently of theflange portion 454. - The
cap 46 has a flat or substantially flat annular shape. The outer peripheral portion of thecap 46 is fixed to the upper portion of theflange portion 454. The inner peripheral portion of thecap 46 is positioned above the upper opposingportion 43. The inner peripheral end portion of the cap is bent downward. The upper portion of the upper opposingportion 43 preferably includes anannular recess portion 431 depressed downward. The lower end of the inner peripheral end portion of thecap 46 is positioned within therecess portion 431. - The
lower thrust plate 452 has an annular shape. Thelower thrust plate 452 is fixed to the lower portion of thesleeve body 451. The lower surface of thelower thrust plate 452 serves as the lower surface of thesleeve portion 45. A lowerhorizontal communication path 542 serving as a second communication path is defined between thesleeve body 451 and thelower thrust plate 452. The lowerhorizontal communication path 542 extends from the lower end of thevertical communication path 541 to the outer circumferential surface of thesleeve portion 45. The lowerhorizontal communication path 542 can be easily defined by thelower thrust plate 452. - The
upper thrust plate 453 has an annular shape. Theupper thrust plate 453 is fixed to the upper portion of thesleeve body 451. The upper surface of theupper thrust plate 453 serves as the upper surface of thesleeve portion 45. An upperhorizontal communication path 543 serving as a third communication path is defined between thesleeve body 451 and theupper thrust plate 453. The upperhorizontal communication path 543 extends from the upper end of thevertical communication path 541 to the outer circumferential surface of thesleeve portion 45. The upperhorizontal communication path 543 can be easily defined by theupper thrust plate 453. As stated above, thesleeve portion 45 preferably includes communication paths which include thevertical communication path 541, the lowerhorizontal communication path 542 and the upperhorizontal communication path 543. -
FIG. 4 is a sectional view of thesleeve body 451, which additionally shows those portions lying more inward. Dynamic pressure grooves are preferably arranged on the inner circumferential surface of thesleeve body 451, namely on the inner circumferential surface of thesleeve portion 45. Consequently, as shown inFIG. 3 , a radial dynamic-pressure bearing portion 51 a is provided in aradial gap 51 between the outer circumferential surface of theshaft portion 41 and the inner circumferential surface of thesleeve portion 45. The radial dynamic-pressure bearing portion 51 a preferably includes an upper radial dynamic-pressure bearing portion 511 and a lower radial dynamic-pressure bearing portion 512. The upper radial dynamic-pressure bearing portion 511 preferably includes a herringbone-shaped upper radial dynamic-pressure groove array 611. The lower radial dynamic-pressure bearing portion 512 preferably includes a herringbone-shaped lower radial dynamic-pressure groove array 612. In the upper radial dynamic-pressure groove array 611, the axial length of an upper herringbone region is preferably larger than the axial length of a lower herringbone region. In the lower radial dynamic-pressure groove array 612, the axial length of an upper herringbone region is preferably equal or substantially equal to the axial length of a lower herringbone region. -
FIG. 5 is a plan view of the lower opposingportion 42 according to a preferred embodiment of the present invention. A spiral lower thrust dynamic-pressure groove array 621 serving as a dynamic pressure generating groove array is arranged on the upper surface of the lower opposingportion 42. As shown inFIG. 3 , a lower thrust dynamic-pressure bearing portion 52 a is defined in alower thrust gap 52 between the lower surface of thesleeve portion 45 and the upper surface of the lower opposingportion 42. In other words, the upper surface of the lower opposing portion is axially opposed to the lower end surface of thesleeve portion 45 through thelower thrust gap 52.FIG. 6 is a plan view of theupper thrust plate 453. A spiral upper thrust dynamic-pressure groove array 622 serving as a dynamic pressure generating groove array is preferably arranged on the upper surface of theupper thrust plate 453. As shown inFIG. 3 , an upper thrust dynamic-pressure bearing portion 53 a is defined in anupper thrust gap 53 between the upper end surface of thesleeve portion 45 and the lower surface of the upper opposingportion 43. In other words, the lower surface of the upper opposingportion 43 is axially opposed to the upper end surface of thesleeve portion 45 through theupper thrust gap 53. A lower seal portion 56 a is preferably defined in a lower seal gap between the outer circumferential surface of thesleeve portion 45 and the inner circumferential surface of the lower outer ring-shapedportion 44. - While the upper surface of the
upper thrust plate 453 preferably includes a thrust dynamic-pressure groove array, the lower surface of thelower thrust plate 452 preferably does not include a thrust dynamic-pressure groove array. Thus, it is possible to prevent a worker from confusing theupper thrust plate 453 with thelower thrust plate 452 when assembling thebearing mechanism 4. -
FIG. 7 is an enlarged sectional view showing the lowerhorizontal communication path 542 and its vicinity.FIG. 8 is a plan view of thelower thrust plate 452. The upper surface of thelower thrust plate 452 preferably includes aheight variation portion 641. Theheight variation portion 641 is preferably provided in the entire periphery of the upper surface of thelower thrust plate 452. The radial outer region of theheight variation portion 641 is positioned axially below the radial inner region of theheight variation portion 641. The radial outer region of theheight variation portion 641 defines the lowerhorizontal communication path 542 in cooperation with the lower portion of thesleeve body 451. Since theheight variation portion 641 is provided in the entire periphery of the upper surface of thelower thrust plate 452, it becomes possible to attach thelower thrust plate 452 to thesleeve body 451 without having to give consideration to the orientation of thelower thrust plate 452. The upper surface of thelower thrust plate 452 preferably includes a plurality of radially-extendingadhesive agent grooves 642 arranged radially inward of theheight variation portion 641. - The
sleeve body 451 preferably includes a lowerannular surface 461 radially extending about the center axis J1 and opposed to the upper surface of thelower thrust plate 452. The lowerannular surface 461 is a portion of the lower surface of thesleeve body 451. Thevertical communication path 541 preferably includes alower opening portion 544 opened on the lowerannular surface 461. At least a portion of the radial outer region of theheight variation portion 641 of thelower thrust plate 452 shown inFIG. 8 is axially opposed to thelower opening portion 544. - The lower inner peripheral portion of the
sleeve body 451 preferably includes alower protrusion portion 456 protruding downward. Thelower protrusion portion 456 is inserted into thelower thrust plate 452. By providing thelower protrusion portion 456, it is possible to easily attach thelower thrust plate 452 in a desired position. - The outer diameter of the
lower thrust plate 452 is smaller than the outer diameter of the lower portion of thesleeve body 451. In other words, thesleeve body 451 preferably includes a large-diameter portion arranged in the lower portion thereof. Thelower thrust plate 452 serves as a small-diameter portion. The lower portion of thesleeve portion 45 preferably includes a large-diameter portion and a small-diameter portion positioned below the large-diameter portion and having a diameter smaller than the diameter of the large-diameter portion. The outer peripheral portion of the lower opposingportion 42 preferably includes an outerperiphery protrusion portion 421 protruding upward. The outerperiphery protrusion portion 421 is positioned inside the lower outer ring-shapedportion 44. The outerperiphery protrusion portion 421 is positioned radially outward of thelower thrust plate 452. In other words, the outerperiphery protrusion portion 421 is radially opposed to the outer circumferential surface of the small-diameter portion of thesleeve portion 45. An axially-extendingvertical gap 551 is defined between the outer circumferential surface of thelower thrust plate 452 and the inner circumferential surface of the outerperiphery protrusion portion 421. The upper end of thevertical gap 551 is connected to the outer peripheral portion of the lowerhorizontal communication path 542. The lower end of thevertical gap 551 is connected to the outer peripheral portion of thelower thrust gap 52. - The outer
periphery protrusion portion 421 is axially opposed to the lower portion of thesleeve body 451. In other words, the upper surface of the outerperiphery protrusion portion 421 is axially opposed to the lower surface of the large-diameter portion of thesleeve portion 45. Ahorizontal gap 552 is defined between the upper surface of the outerperiphery protrusion portion 421 and the lowerannular surface 461 of thesleeve body 451. Thehorizontal gap 552 extends in the radial direction. The inner peripheral portion of thehorizontal gap 552 is connected to the outer peripheral portion of the lowerhorizontal communication path 542. The outer peripheral portion of thehorizontal gap 552 is connected to the lower end of thelower seal gap 56. - The lower
horizontal communication path 542 defined by thelower thrust plate 452 essentially interconnects thelower opening portion 544 of thevertical communication path 541 and thelower seal gap 56. In other words, thehorizontal gap 552 can be regarded as a portion of the lower seal portion 56 a. Thelower opening portion 544 of thevertical communication path 541 axially overlaps with the lower thrust dynamic-pressure bearing portion 52 a. This makes it possible to easily increase the size of the lower thrust dynamic-pressure bearing portion 52 a. As a result, it is possible to easily obtain a large enough levitation force required for the lower thrust dynamic-pressure bearing portion 52 a to lift therotary unit 3. - The lower seal portion 56 a serves as a pumping seal portion and preferably includes a
pumping section 561 and abuffer section 562. The lower end of thepumping section 561 is connected to the outer peripheral portion of thehorizontal gap 552. Thebuffer section 562 is positioned above thepumping section 561 and is connected to the upper end of thepumping section 561. In thepumping section 561, thelower seal gap 56 has a cylindrical or substantially cylindrical shape. In thepumping section 561, spiral grooves are arranged on the inner circumferential surface of the lower outer ring-shapedportion 44. In thepumping section 561, a force which pushes thelubricant 47 downward is generated by the rotation of thesleeve portion 45. - In the
buffer section 562, the outer circumferential surface of thesleeve portion 45 is inclined radially inward and upward. In thebuffer section 562, the radial width of thelower seal gap 56 is gradually increased upward. When thesleeve portion 45 is kept stationary, a boundary surface of thelubricant 47 is preferably arranged in thebuffer section 562. When thesleeve portion 45 rotates, thelubricant 47 flows from thebuffer section 562 toward thepumping section 561. Thus, the boundary surface of thelubricant 47 moves downward. Alternatively, the boundary surface may be positioned within thepumping section 561. -
FIG. 9 is an enlarged sectional view showing the upperhorizontal communication path 543 and its vicinity. The lower surface of theupper thrust plate 453 preferably has substantially the same shape as the plan-view shape of thelower thrust plate 452 shown inFIG. 8 . In other words, the lower surface of theupper thrust plate 453 preferably includes a height variation portion. The height variation portion is preferably provided on the entire periphery of the lower surface of theupper thrust plate 453. The radial outer region of the height variation portion is positioned axially above the radial inner region of the height variation portion. The radial outer region of the height variation portion defines the upperhorizontal communication path 543 in cooperation with the upper portion of thesleeve body 451. Since the height variation portion is provided in the entire periphery of the lower surface of theupper thrust plate 453, it becomes possible to attach theupper thrust plate 453 to thesleeve body 451 without having to give consideration to the orientation of theupper thrust plate 453. As shown inFIG. 8 , a plurality of radially-extending adhesive agent grooves is arranged radially inward of the height variation portion. - The
sleeve body 451 preferably includes an upperannular surface 462 radially extending about the center axis J1 and opposed to the lower surface of theupper thrust plate 453. The upperannular surface 462 is a portion of the upper surface of thesleeve body 451. Thevertical communication path 541 preferably includes anupper opening portion 545 opened on the upperannular surface 462. At least a portion of the radial outer region of the height variation portion of theupper thrust plate 453 is axially opposed to theupper opening portion 545. - The upper inner peripheral portion of the
sleeve body 451 preferably includes anupper protrusion portion 459 protruding upward. Theupper protrusion portion 459 is inserted into theupper thrust plate 453. By providing theupper protrusion portion 459, it is preferably possible to easily attach theupper thrust plate 453 in a desired position. The upper end of theupper protrusion portion 459 is positioned axially above the upper surface of theupper thrust plate 453. A portion of the radial dynamic-pressure bearing portion 51 a radially overlaps with theupper thrust plate 453. In other words, the radial dynamic-pressure bearing portion 51 a can be positioned upward by providing theupper protrusion portion 459. As a result, the center of therotary unit 3 and the center of the radial dynamic-pressure bearing portion 51 a can be caused to come close to each other. This makes it possible to significantly reduce and prevent vibration. - Since the upper
horizontal communication path 543 is defined by theupper thrust plate 453, theupper opening portion 545 axially overlaps with the upper thrust dynamic-pressure bearing portion 53 a. This makes it possible to increase the size of the upper thrust dynamic-pressure bearing portion 53 a. - The inner peripheral portion of the
flange portion 454 protrudes upward from the outer peripheral portion of thesleeve body 451 and surrounds the radial outer surface of the upper opposingportion 43. In other words, the cylindrical or substantially cylindrical inner circumferential surface of theflange portion 454 surrounds at least a portion of the outer circumferential surface of the upper opposingportion 43 at the radial outer side. The inner circumferential surface of theflange portion 454 is radially opposed to the outer circumferential surface of theupper thrust plate 453. In the following description, the inner peripheral portion of theflange portion 454 will be referred to as “upper outer ring-shapedportion 455”. The upper outer ring-shapedportion 455 is a portion whose relative position is fixed with respect to thesleeve portion 45. - An
upper seal gap 57 is defined between the inner circumferential surface of the upper outer ring-shapedportion 455 and the outer circumferential surface of the upper opposingportion 43. The upperhorizontal communication path 543 interconnects theupper opening portion 545 and theupper seal gap 57. Theupper seal gap 57 defines an upper seal portion 57 a. An axially-extendingvertical gap 553 is defined between the outer circumferential surface of theupper thrust plate 453 and the inner circumferential surface of the upper outer ring-shapedportion 455. The upper end of thevertical gap 553 is joined to the lower end of theupper seal gap 57 and the outer peripheral portion of theupper thrust gap 53. In other words, theupper seal gap 57 is joined to theupper thrust gap 53. The lower end of thevertical gap 553 is connected to the outer peripheral portion of the upperhorizontal communication path 543. - The radial width of the
upper seal gap 57 is increased upward. In the upper seal portion 57 a, the outer circumferential surface of the upper opposingportion 43 is preferably inclined radially inward and upward. Likewise, the inner circumferential surface of the upper outer ring-shapedportion 455 is inclined radially inward and upward. In this manner, the upper seal portion 57 a is inclined radially inward and upward. Accordingly, any air bubbles existing within thelubricant 47 can be efficiently discharged through the use of centrifugal forces acting on thelubricant 47. - As shown in
FIG. 3 , there is provided acirculation path 50 mainly defined by thelower thrust gap 52, theradial gap 51, theupper thrust gap 53, thevertical gap 553, the upperhorizontal communication path 543, thevertical communication path 541, the lowerhorizontal communication path 542 and thevertical gap 551. Thecirculation path 50 is filled with thelubricant 47. Thecirculation path 50 and thelower seal gap 56 communicate with each other. Thecirculation path 50 and theupper seal gap 57 communicate with each other. Thelubricant 47 is filled over a range extending from thecirculation path 50 to thelower seal gap 56 and is also filled over a range extending from thecirculation path 50 to theupper seal gap 57. In other words, thehorizontal gap 552 extending from the radial outer opening of the lowerhorizontal communication path 542 to thelower seal gap 56 is preferably filled with thelubricant 47. Thevertical gap 553 extending from the radial outer opening of the upperhorizontal communication path 543 to theupper seal gap 57 is also filled with thelubricant 47. - Since the
motor 12 is provided with thelower thrust plate 452 and theupper thrust plate 453, it is possible to increase the load capacity and to reduce the levitation start revolution number. Inasmuch as the sliding contact time in the thrust bearing becomes shorter during the startup and stop operations, it is possible to prolong the lifespan of themotor 12. By enhancing the thrust bearing performance, it is possible to increase the shaft diameter and to reduce the bearing attenuation. This makes it possible to significantly reduce and prevent the vibration response at a high frequency. Thelower thrust plate 452 and theupper thrust plate 453 are preferably manufactured by, for example, pressing, cutting, etc. Thelower thrust plate 452 and theupper thrust plate 453 may be made of a solid material or a sintered material. - As mentioned earlier, in the upper radial dynamic-
pressure groove array 611, the axial length of the upper herringbone region is preferably larger than the axial length of the lower herringbone region. In the lower radial dynamic-pressure groove array 612, the axial length of the upper herringbone region is preferably equal or substantially equal to the axial length of the lower herringbone region. Consequently, a dynamic pressure acting to push thelubricant 47 axially downward is generated in the radial dynamic-pressure bearing portion 51 a. In thecirculation path 50, due to the dynamic pressure thus generated, thelubricant 47 flows downward along theradial gap 51 during the rotation of thesleeve portion 45. Accordingly, it is possible to easily prevent generation of a negative pressure in the lower seal portion 56 a as a pumping seal portion. -
FIG. 10 is a schematic diagram showing thelower thrust plate 452 and its vicinity. InFIG. 10 and the similar figures to be described below, the cross section is not hatched. When manufacturing thebearing mechanism 4, thelubricant 47 is preferably injected from theupper seal gap 57. In thebearing mechanism 4, thesleeve body 451 and theflange portion 454 are preferably formed as a single monolithic member. For that reason, it is almost impossible to inject thelubricant 47 from thelower seal gap 56. When injecting thelubricant 47, as shown inFIG. 10 , the lower surface of thelower thrust plate 452 makes contact with the upper surface of the lower opposingportion 42 in the axial direction. - There is a likelihood that, during the injection process, the
lubricant 47 flowing through thevertical communication path 541 and the lowerhorizontal communication path 542 may be stopped in ahorizontal opening portion 546 as an outlet of the lowerhorizontal communication path 542 due to the surface tension of thelubricant 47. Thehorizontal opening portion 546 is preferably opened in a border between the lower portion of thesleeve body 451 and thelower thrust plate 452, namely a border between the large-diameter portion and the small-diameter portion. In the present preferred embodiment, thehorizontal opening portion 546 is positioned on the outer circumferential surface of thelower thrust plate 452. In thebearing mechanism 4 of the present preferred embodiment, the outerperiphery protrusion portion 421 is arranged to protrude toward thehorizontal opening portion 546 such that thelubricant 47 reaching thehorizontal opening portion 546 comes into contact with the outerperiphery protrusion portion 421. This makes it possible to easily guide thelubricant 47 to thevertical gap 551, thehorizontal gap 552, and thelower seal gap 56. - When the
sleeve portion 45 is kept stationary, namely when the lower surface of thesleeve portion 45 makes contact with the upper surface of the lower opposingportion 42 in the axial direction, theminimum radial width 72 between the outer circumferential surface of thelower thrust plate 452 and the inner circumferential surface of the outerperiphery protrusion portion 421 and the minimumaxial width 73 between the lower surface of the lower portion of thesleeve body 451 and the upper surface of the outerperiphery protrusion portion 421 is preferably equal to or smaller than theaxial width 71 of the radial outer opening of the lowerhorizontal communication path 542. Moreover, the upper surface of the region of thelower thrust plate 452 arranged radially outward of theheight variation portion 641 is preferably positioned below the upper surface of the outerperiphery protrusion portion 421. More preferably, on the cross section including the center axis J1, thestraight line 76 interconnecting the outer edge of the lower surface of thelower thrust plate 452 and the outer edge of the lower surface of the lower portion of thesleeve body 451 extends across the outerperiphery protrusion portion 421. This preferably makes it possible to fill thelubricant 47 with ease. The “outer edge of the lower surface” preferably does not include any chamfered portion. - The structure mentioned just above is especially suitable in a case where the upper portion of the outer peripheral portion of the
sleeve portion 45 extends radially outward of the lower seal portion 56 a and in a case where thelubricant 47 cannot be virtually injected from the lower seal portion 56 a. -
FIG. 11 is a schematic diagram showing thelower thrust plate 452 in accordance with a preferred embodiment of the present invention and its vicinity. Thelower thrust plate 452 is preferably bonded to thesleeve body 451 by anadhesive agent 78. Use of theadhesive agent 78 makes it possible to fit thelower thrust plate 452 to thelower protrusion portion 456 in a running fit state. This makes it possible to prevent deformation of thelower thrust plate 452 which would be caused by, for example, press fitting. Theadhesive agent 78 is applied on the lower surface of thesleeve body 451 or the upper surface of thelower thrust plate 452. Then, thelower thrust plate 452 is attached to thesleeve body 451. Theadhesive agent 78 is arranged in at least a portion of the inner surface of each of theadhesive agent grooves 642 of thelower thrust plate 452. By providing theadhesive agent grooves 642, it is possible to easily expand the circumferentially-appliedadhesive agent 78 in the radial direction. As a result, it becomes possible to secure the required bonding strength. Preferably, theadhesive agent 78 is, for example, a thermosetting adhesive agent whose viscosity is decreased prior to occurrence of hardening caused by heating. - In general, the
adhesive agent 78 is slightly extruded from the radial outer end portions of theadhesive agent grooves 642. Theheight variation portion 641 of thelower thrust plate 452 preferably includes aheight variation surface 640 inclined radially inward and upward. Theadhesive agent 78 extruded radially outward from theadhesive agent grooves 642 is held between theheight variation surface 640 and the lowerannular surface 461 of thesleeve body 451. - The
adhesive agent 78 extruded radially inward from theadhesive agent grooves 642 is preferably provided between the outercircumferential surface 458 of thelower protrusion portion 456 and the innercircumferential surface 644 of thelower thrust plate 452. In the following description, the gap defined between the outercircumferential surface 458 of thelower protrusion portion 456 and the innercircumferential surface 644 of thelower thrust plate 452 will be referred to as “verticaladhesive agent gap 781”. The lower portion of the outercircumferential surface 458 is preferably a slant surface inclined radially inward and downward. Thus, theadhesive agent 78 is held stably. More specifically, the lower portion of the verticaladhesive agent gap 781 preferably includes an adhesiveagent holding gap 782 whose radial width is gradually increased downward. - The inner
circumferential surface 644 of thelower thrust plate 452 may be inclined radially outward and downward. In other words, in the adhesiveagent holding gap 782, the outercircumferential surface 458 of thelower protrusion portion 456 is inclined radially inward and downward and the innercircumferential surface 644 of thelower thrust plate 452 is parallel or substantially parallel to the center axis J1 or inclined radially outward and downward. In the adhesiveagent holding gap 782, the angle between the outercircumferential surface 458 of thelower protrusion portion 456 and the center axis J1 is larger than the angle between the innercircumferential surface 644 of thelower thrust plate 452 and the center axis J1. This makes it possible to easily secure the size of the lower thrust dynamic-pressure bearing portion 52 a while providing the adhesiveagent holding gap 782. - As shown in
FIG. 12 , theaxial depth 74 of theadhesive agent grooves 642 is preferably smaller than theaxial width 71 of the lowerhorizontal communication path 542. Theminimum radial width 75 of the verticaladhesive agent gap 781 is also preferably smaller than theaxial width 71. Thus, theadhesive agent 78 extruding into the lowerhorizontal communication path 542 is pushed toward theadhesive agent grooves 642 and the verticaladhesive agent gap 781 by a capillary phenomenon such that theadhesive agent 78 is preferably prevented from clogging thevertical communication path 541. It should be noted that only a singleadhesive agent groove 642 may be provided if so desired. -
FIG. 13 is a plan view showing another example of thelower thrust plate 452 in accordance with a preferred embodiment of the present invention. In thelower thrust plate 452 shown inFIG. 13 , theheight variation portion 641 is provided in only a portion of thelower thrust plate 452 along the circumferential direction. In other words, only a portion of the outer edge portion of thelower thrust plate 452 along the circumferential direction is depressed downward. Other configurations of thelower thrust plate 452 shown inFIG. 13 remain the same as those of thelower thrust plate 452 shown inFIG. 8 . When assembling thebearing mechanism 4, thelower thrust plate 452 is preferably attached to the lower portion of thesleeve body 451 in such a fashion that the radial outer region of theheight variation portion 641 overlaps with thelower opening portion 544 of thevertical communication path 541. -
FIG. 14 is a sectional view showing a further example of thelower thrust plate 452 in accordance with a preferred embodiment of the present invention. The upper surface of thelower thrust plate 452 shown inFIG. 14 preferably includes aheight variation portion 643. The radial inner region of theheight variation portion 643 is positioned axially below the radial outer region thereof. At least a portion of the radial inner region of theheight variation portion 643 axially overlaps with thelower opening portion 544 of thevertical communication path 541. The upper surface of thelower thrust plate 452 preferably includes agroove 646 extending from theheight variation portion 643 to the outer circumferential surface of thelower thrust plate 452. As thelower thrust plate 452 is attached to thesleeve body 451, a lowerhorizontal communication path 542 is preferably defined by the lower surface of thesleeve body 451 and thegroove 646. The gap between the outer circumferential surface of thelower protrusion portion 456 of thesleeve body 451 and the inner circumferential surface of thelower thrust plate 452 is preferably sealed by theadhesive agent 78. With this structure, it is possible to easily provide the lowerhorizontal communication path 542. - A depression portion positioned axially below the remaining portion on the upper surface of the
lower thrust plate 452 may be provided in many different shapes and arrangements as long as the depression portion overlaps with the lower opening of thevertical communication path 541. For example, a depression portion may be provided at the radial center of thelower thrust plate 452. A lowerhorizontal communication path 542 can be provided in thesleeve portion 45 by providing a recess portion, such as, for example, a groove or the like, which extends from the depression portion to the outer circumferential surface of thelower thrust plate 452. -
FIG. 15 is a view showing a still further example of thelower thrust plate 452 and thesleeve body 451. In the example shown inFIG. 15 , the lower surface of thesleeve body 451 preferably includes aheight variation portion 645. The radial outer region of theheight variation portion 645 is preferably positioned axially above the radial inner area thereof. Theheight variation portion 645 may be provided only in the vicinity of the lower opening of thevertical communication path 541 or may be provided in the entire periphery of the lower surface of thesleeve body 451. The upper surface of thelower thrust plate 452 is planar. A radially-extending adhesive agent groove may be provided on the upper surface of thelower thrust plate 452. As thelower thrust plate 452 is attached to the lower portion of thesleeve body 451, a radially-extending lowerhorizontal communication path 542 is defined between the radial outer region of theheight variation portion 645 and the upper surface of thelower thrust plate 452. With the structure shown inFIG. 15 , it is possible to easily provide the lowerhorizontal communication path 542. It is also possible to simplify the shape of thelower thrust plate 452. -
FIG. 16 is a view showing another example of thebearing mechanism 4 of a preferred embodiment of the present invention. Thebearing mechanism 4 shown inFIG. 16 is not provided with an upper thrust dynamic-pressure bearing portion. - Other configurations of the
bearing mechanism 4 shown inFIG. 16 remain the same as those of thebearing mechanism 4 shown inFIG. 3 . The same configurations as those shown inFIG. 3 will be designated by like reference symbols. - In the
bearing mechanism 4 shown inFIG. 16 , thevertical communication path 541 is preferably inclined radially inward and upward. The upper surface of thesleeve body 451 is opposed to the lower surface of the upper opposingportion 43. In the following description, the gap defined between the upper surface of thesleeve body 451 and the lower surface of the upper opposingportion 43 will be referred to as “upper thrust gap 58”. In other words, the lower surface of the upper opposing portion is axially opposed to the upper end surface of thesleeve portion 45 through theupper thrust gap 58. However, theupper thrust gap 58 preferably only serves as a gap and does not define up an upper thrust dynamic-pressure bearing portion. - The upper opening of the
vertical communication path 541 axially overlaps with the lower surface of the upper opposingportion 43. Anupper seal gap 57 is defined between the outer circumferential surface of the upper opposingportion 43 and the inner circumferential surface of the upper outer ring-shapedportion 455. Alubricant 47 is held within theupper seal gap 57 so as to define an upper seal portion 57 a. The upper seal portion 57 a is inclined radially inward and upward. Thus, air bubbles existing within thelubricant 47 are efficiently discharged from the upper seal portion 57 a. Thevertical communication path 541 is substantially joined to theupper seal gap 57. - A magnetically-generated downward force acts on the
sleeve portion 45. Thesleeve portion 45 is preferably axially supported by only the lower thrust dynamic-pressure bearing portion 52 a. As is the case inFIG. 3 , there is provided acirculation path 50 mainly defined by thelower thrust gap 52, theradial gap 51, theupper thrust gap 58, thevertical communication path 541, the lowerhorizontal communication path 542, and thevertical gap 551. Thecirculation path 50 is filled with thelubricant 47. Thecirculation path 50 and theupper seal gap 57 communicate with each other. Thecirculation path 50 and theupper seal gap 57 are filled with thelubricant 47. The outer peripheral portion of theupper thrust gap 58 communicates with theupper seal gap 57. In thecirculation path 50, thelubricant 47 flows downward along theradial gap 51 during the rotation of thesleeve portion 45. - The structure near the
lower thrust plate 452 and the filling method of thelubricant 47 preferably remain the same as those shown inFIG. 3 or described in other examples. Accordingly, it is possible to fill thelubricant 47 with ease. -
FIG. 17 is a view showing a further example of thebearing mechanism 4 according to a preferred embodiment of the present invention. Thebearing mechanism 4 shown inFIG. 17 is preferably not provided with thelower thrust plate 452 and theupper thrust plate 453 shown inFIG. 3 . In the example shown inFIG. 17 , the portions corresponding to the lower portion of thesleeve body 451 and thelower thrust plate 452 shown inFIG. 3 are preferably continuously integrated with each other as a single monolithic member. Additionally, the portions corresponding to the upper portion of thesleeve body 451 and theupper thrust plate 453 shown inFIG. 3 are also continuously integrated with each other as a single monolithic member. Thesleeve portion 45 including the portions corresponding to thesleeve body 451, thelower thrust plate 452, theupper thrust plate 453, and theflange portion 454 is preferably defined by anupper bearing member 481 including an upper radial dynamic-pressure groove array 611 and alower bearing member 482 including a lower radial dynamic-pressure groove array 612. - The
upper bearing member 481 is a member arranged near the upper radial dynamic-pressure groove array 611. Thelower bearing member 482 is a member corresponding to the lower portion of thesleeve body 451, the outer peripheral portion of the upper portion of thesleeve body 451 and theflange portion 454 shown inFIG. 3 . Other configurations of thebearing mechanism 4 shown inFIG. 17 remain the same as those of thebearing mechanism 4 shown inFIG. 3 . The same configurations as those shown inFIG. 3 will be designated by like reference symbols. - As is the case in
FIG. 3 , thesleeve portion 45 preferably includes avertical communication path 541 as a first communication path, a lowerhorizontal communication path 542 as a second communication path, and an upperhorizontal communication path 543 as a third communication path. Preferably, the outer circumferential surface of theupper bearing member 481 axially overlaps with thevertical communication path 541. This makes it possible to provide thevertical communication path 541 with ease. The lowerhorizontal communication path 542 and the upperhorizontal communication path 543 may be provided only near the end portion of thevertical communication path 541 or may be provided in an annular shape over the entire periphery. - In the
bearing mechanism 4 shown inFIG. 17 , the lower portion of thesleeve portion 45 preferably includes a large-diameter portion 651 and a small-diameter portion 652. The small-diameter portion 652 is smaller in diameter than the large-diameter portion 651. The small-diameter portion 652 is the lowermost portion of thesleeve portion 45 and is positioned below the large-diameter portion 651. The lower opposingportion 42 preferably includes an outerperiphery protrusion portion 421. - Accordingly, it is preferably possible to easily fill the
lubricant 47 from theupper seal gap 57. - As shown in
FIG. 18 , if so desired, a structure not provided with any thrust plate may be applied to thebearing mechanism 4 shown inFIG. 16 . In thebearing mechanism 4 shown inFIG. 18 , thesleeve body 451 and thelower thrust plate 452 shown inFIG. 16 are continuously defined with each other as a single monolithic member. Other configurations of thebearing mechanism 4 shown inFIG. 18 remain the same as those of thebearing mechanism 4 shown inFIG. 16 . The same configurations as those shown inFIG. 16 will be designated by like reference symbols. - In the
bearing mechanism 4 shown inFIG. 18 , thesleeve portion 45 preferably includes a large-diameter portion 651 and a small-diameter portion 652 as in thebearing mechanism 4 shown inFIG. 17 . The lower opposingportion 42 preferably includes an outerperiphery protrusion portion 421. Accordingly, it is preferably possible to easily fill thelubricant 47 from theupper seal gap 57. - While certain preferred embodiments of the present invention have been described above, the present invention is not limited thereto and may be modified in many different forms.
- For example, the radial dynamic-pressure groove array may be arranged on the outer circumferential surface of the
shaft portion 41. Similarly, the lower thrust dynamic-pressure groove array 621 may be provided on the lower surface of thelower thrust plate 452 and the upper thrust dynamic-pressure groove array 622 may be provided on the lower surface of the upper opposingportion 43. - The
lower thrust plate 452 and theupper thrust plate 453 may be attached to thesleeve body 451 preferably by, for example, press-fitting, press-fitting and bonding, welding, caulking, etc. - In the
bearing mechanisms 4 shown inFIGS. 17 and 18 , thelower opening portion 544 need not be necessarily positioned in the border between the large-diameter portion 651 and the small-diameter portion 652 but may instead be positioned near the border. - The
motor 12 may be an inner rotor type motor. Themotor 12 can be used in a disk drive apparatus other than the hard disk drive apparatus, e.g., an optical disk drive apparatus. Moreover, themotor 12 can be used in other applications than the disk drive apparatus. For example, themotor 12 can be used as a polygon scanner motor in a laser beam printer, a color wheel driving motor in a projector, etc. - The preferred embodiments of the present invention are applicable to a bearing mechanism for motors having different purposes. In addition, the preferred embodiments of the present invention can be applied to a bearing mechanism for other applications than motors.
- Features of the above-described preferred embodiments and the modifications thereof may be combined appropriately as long as no conflict arises.
- While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.
Claims (16)
Applications Claiming Priority (2)
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JP2012-123006 | 2012-05-30 | ||
JP2012123006A JP5812351B2 (en) | 2012-05-30 | 2012-05-30 | Bearing mechanism, motor and disk drive |
Publications (2)
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US8587895B1 US8587895B1 (en) | 2013-11-19 |
US20130321952A1 true US20130321952A1 (en) | 2013-12-05 |
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US13/785,297 Expired - Fee Related US8587895B1 (en) | 2012-05-30 | 2013-03-05 | Bearing mechanism, motor and disk drive apparatus |
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US (1) | US8587895B1 (en) |
JP (1) | JP5812351B2 (en) |
CN (1) | CN103453020B (en) |
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-
2013
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- 2013-05-15 CN CN201310179589.1A patent/CN103453020B/en not_active Expired - Fee Related
Also Published As
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JP2013249851A (en) | 2013-12-12 |
CN103453020A (en) | 2013-12-18 |
US8587895B1 (en) | 2013-11-19 |
CN103453020B (en) | 2016-03-09 |
JP5812351B2 (en) | 2015-11-11 |
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