Classifications

• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
• • 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
• • 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
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B25/00—Apparatus characterised by the shape of record carrier employed but not specific to the method of recording or reproducing, e.g. dictating apparatus; Combinations of such apparatus
  • G11B25/04—Apparatus characterised by the shape of record carrier employed but not specific to the method of recording or reproducing, e.g. dictating apparatus; Combinations of such apparatus using flat record carriers, e.g. disc, card
  • G11B25/043—Apparatus characterised by the shape of record carrier employed but not specific to the method of recording or reproducing, e.g. dictating apparatus; Combinations of such apparatus using flat record carriers, e.g. disc, card using rotating discs

Definitions

• the present invention relates to magnetic disc drive storage systems
• the present invention relates to a hydrodynamic fluid bearing for use
• Magnetic disc drives are used for magnetically storing information.
• a magnetic disc drive a magnetic disc rotates at high speed and a transducing head "flies"
• This transducing head records information on the disc surface by impressing a magnetic field on the disc. Information is read back using the head by
• the transducing head is moved radially
• One typical bearing assembly comprises ball bearings supported between a pair races which allow a hub of a storage disc to rotate relative to a fixed member.
• ball bearing assemblies have many mechanical problems such as wear, run-out and manufacturing difficulties.
• resistance to operating shock and vibration is poor, because of low damping.
• a lubricating fluid such as air or liquid provides a bearing surface between a fixed member of the housing and a rotating member of the
• typical lubricants include oil or ferromagnetic fluids.
• Hydrodynamic bearings spread the bearing interface over a large surface area in comparison with a ball bearing assembly which comprises a series of point interfaces.
• hydrodynamic bearings themselves suffer from disadvantages, including a low stiffiiess-to-power ratio. These problems lead to a high sensitivity of the bearing to external loads or shock.
• Another objective of the invention is to provide a hydrodynamic bearing having increased stiffness.
• Another objective of the invention is to provide a hydrodynamic bearing useful in a spindle motor for a disc drive or the like which is stiffer than known standard spindle motors so that the stability of the system and specifically of the actuator arm and
• a counter plate and/or a sleeve which is capable of relative rotation around the shaft.
• the bearing includes a fixed shaft and a sleeve rotating around and surrounding the shaft, and at least first and second thrust plates separated by a portion of the shaft.
• the shaft includes a central reservoir or hole and one or more ports between the reservoir and a gap defined
• Grooves can be found on shaft or sleeve to enhance fluid circulation through the gaps defined by the shaft and the thrust plates supported thereon and the surrounding sleeve with counter-plates, as well as to increase stiffness. Grooves could also appear on one or more of the counterplates, or on a thrust plate surface, or a combination of both thrust plate and counterplate.
• the bores may include at least one radial bore between each pair of thrust plates, and a further radial bore below the lowermost thrust plate.
• Assembly is enhanced by providing axially separated steps in the sleeve so
• shaft and thrust plates may be inserted into the sleeve, with counterplates then placed against the steps in the sleeve.
• Figure 1 is a perspective view of a magnetic disc storage system which may incorporate the hydrodynamic bearing cartridge and spindle motor in accordance with the present invention.
• Figure is a vertical sectional view of a prior art hydrodynamic bearing cartridge incorporated in a spindle motor assembly.
• Figure 3 is a vertical sectional view of a hydrodynamic bearing cartridge in accordance with the present invention.
• FIG 1 is an exploded perspective view of a magnetic disc drive storage system in which the present hydrodynamic bearing cartridge could be used.
• the use of the hydrodynamic bearing and associated cartridge will be shown in conjunction with a spindle motor.
• this bearing cartridge is not limited to use with this particular design of a disc drive, which is shown
• bearing cartridge also has numerous other uses outside of the field of disc drives.
• fluid bearing disclosed herein has a fixed shaft and rotating
• the storage system 10 includes a housing base 12
• discs 16 rotate at high speed while transducers 20 are positioned at any one of a large number of radially differentiated tracks on the surface of the discs 16. This allows the transducers 20 to read and write magnetically encoded information on the surfaces of discs 16 at selected locations.
• the discs rotate at very high speeds, several thousand RPM, in order to maintain the transducer flying over the surface of the disc. In present day technology, the spacing
• Figure 2 is a vertical sectional view of a single thrust plate hydrodynamic bearing motor design of a type which is already established in this technology.
• the basic structure of the motor shown in this figure includes a stationary shaft 10 and a hub 12 supported from a sleeve 13 for rotation around the shaft.
• the shaft 10 includes a thrust plate 14 at one end, and terminates in a shoulder 16 at the opposite end.
• the sleeve 13 supports a counterplate 19 at one end, for rotation over the thrust plate 14.
• the counterplate 19 and thrust plate 14 are separated by a sufficient gap 22 to allow movement of lubricating fluid to lubricate the hydrodynamic bearing through the central hole or reservoir 20, through the gap 22, through the reservoir 26 defined between the
• each such assembly typically one of the two opposing surfaces of each such assembly carries sections of grooves as is well known in this technology.
• the fluid flow between the bearing surfaces creates hydrodynamic pressure, resulting in stiffness. Circulation of fluid is maintained through central hole 20 of the shaft to the other bearing surfaces by the appropriate designing of geometry and grooving patterns of the baring surfaces.
• the remainder of the structure of significance which is used to complete the motor design include shaft extension 30 which ends in threaded region 31 which is threaded into a portion of the base 44.
• a stator 42 cooperates with magnets 40 which are supported from the sleeve 13, with energization of the stator windings 42 causing rotation of the sleeve 18 and the hub 12 about the stationary shaft.
• this system supports one or more discs 44 for rotation. Because the transducers and disc drives fly at extremely low heights over the surface of the disc, it is essential that there not be wobble or vibration of the hub and disc as it rotates. Moreover, it is also important that should such wobble occur, that there is no touch down between the surfaces of the thrust plate 14 and the opposing surface of the counterplate 19 and sleeve 13. However, as explained above, in a
• the upper end 101 of shaft 75 supports a thrust plate 90 which rotates below a counterplate 91 supported by sleeve 72; the bottom portion 77 of the shaft 75 is extended to mate with a base (not shown) as indicated and
• the design of the present invention includes at least two thrust plates 90, 92 each mounted on the shaft 75 and spaced apart by a region of the shaft 94.
• Each of the thrust plates 90, 92 are axially
• thrust plates multiple thrust plates may be mounted on the shaft.
• the thrust plate 92 closest to the base faces a section 103 of the sleeve 72 which serves as a counterplate.
• the top surface 214 of the upper thrust plate 90 faces a counterplate 91 which is
• the fluid bearing of this invention is defined between an inner surface of
• the fluid is circulated to the bearing gap 102 through reservoir 105 which extends up the center of the shaft 75 and is connected by one or more radial bores 110, 112, to the gap 102.
• the first radial bore 110 connects the reservoir 105 with the lower gap section 120.
• a second radial bore 112 connects the reservoir 105 with the central
• a reservoir here means that fluid in this region is inactive and does not
• the reservoir communicates with upper gap section 114; grooves on either the
• the lower end 104 of the circulation gap is closed off from the outer
• capillary seal 160 in which the shaft wall section 162 is
• the hydrodynamic bearing fluid is in a narrow gap defined in part by the two thrust plates 90, 92.
• Each thrust plate 90, 92 rotates in a recess 200, 202 respectively defined at its end by an axial wall of the sleeve 72 and on either side by radial walls of the sleeve or counterplates.
• the gap segments are defined by a radial wall 210 of counterplate 91, and a radial wall 214 of the thrust plate 90; then by an end wall 216 of the thrust plate, and an axial wall 218 of the sleeve 72; and finally the gap extends between a radial wall 220 of the thrust plate and a radial wall 222 of
• the gaps provide for motion of the fluid between the fixed shaft and the
• the fluid provides the necessary stiffness and damping, as well as lubrication for rotation of the bearing.
• the fluid circulates from the reservoir 105 out through the lower bore 110, and into the upper gap 114 if it is
• sleeve surfaces directly facing the shaft or the surfaces of the shaft, at the uppermost 101 and lowermost 104 sections of the gap will be grooved using known spiral or herringbone or similar grooving patterns as are already well known in the art to provide the necessary circulation.
• at least one surface of each thrust plate or the facing surface of the associated counterplate will be grooved.
• Such groove patterns are already well known and need not be spelled out in further detail.
• the axial surfaces defining the gap regions 200, 202 at the ends of the thrust plates 90, 92 are not grooved.
• assembly is achieved by providing the sleeve 72 with stepped features 300, 302, which are axially separated and allow the counterplates 91, 93 to be press fitted (or any other suitable method) into place relative to the thrust plates with which they must cooperate.
• the thrust plates are mounted onto the shaft by any suitable method.
• the shaft 75 with the thrust plates 90, 92 is inserted into the sleeve; the counterplate 93 is guided into place by the stepped feature 300; then the top counterplate 91 is fixed in place on step 302 of sleeve 72.
• the thrust plate arrangement enhances the axial stiffness to a considerable degree as well as rocking stiffness of the whole bearing.
• the sleeve can be defined as a single section.
• this bearing can of course be used as a liquid bearing.
• step pumping i.e., by separately pumping sections of the gap around each of the thrust plates and the journal/sleeve regions.
• fluid shall be construed to mean either gas or liquid.
• the shaft may be extended beyond both (or all) thrust plates, rather than ending adjacent one plate, as described in the above incorporated application, without departing from the spirit of the invention.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Mechanical Engineering (AREA)
• Sliding-Contact Bearings (AREA)
• Rotational Drive Of Disk (AREA)
• Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)

Priority Applications (5)

Applications Claiming Priority (4)

Publications (1)

Family

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Family Applications (1)

Country Status (7)

Families Citing this family (21)

Citations (1)

Family Cites Families (4)

• 1997
  • 1997-12-19 US US08/994,100 patent/US6005748A/en not_active Expired - Lifetime
• 1998
  • 1998-04-02 GB GB9828552A patent/GB2330179B/en not_active Expired - Fee Related
  • 1998-04-02 DE DE19880676T patent/DE19880676T1/de not_active Withdrawn
  • 1998-04-02 CN CN98800864A patent/CN1229508A/zh active Pending
  • 1998-04-02 WO PCT/US1998/006635 patent/WO1998048420A1/en not_active Ceased
  • 1998-04-02 JP JP10546069A patent/JP2000514166A/ja not_active Ceased
  • 1998-04-02 KR KR1019980710971A patent/KR100359685B1/ko not_active Expired - Fee Related
• 1999
  • 1999-04-26 US US09/300,006 patent/US6069768A/en not_active Expired - Lifetime

Patent Citations (1)

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