Browse Prior Art Database

Hydrodynamic Bearing Unit

IP.com Disclosure Number: IPCOM000111526D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 111K

Publishing Venue

IBM

Related People

Boutaghou, Z: AUTHOR

Abstract

The present invention deals with spindle operating at high speeds employing hydrodynamic bearings as radial, thrust, conical, or a combination. Further, the present invention deals with the improvement of the hard disk drive spindle performance over traditional approaches using ball bearings and contributes a step towards large scale manufacturing of hydrodynamic bearings. The performance index includes improvement of durability, quiet operation, less vibration, high-speed rotation performance, and sealability.

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Hydrodynamic Bearing Unit

      The present invention deals with spindle operating at high
speeds employing hydrodynamic bearings as radial, thrust, conical, or
a combination.  Further, the present invention deals with the
improvement of the hard disk drive spindle performance over
traditional approaches using ball bearings and contributes a step
towards large scale manufacturing of hydrodynamic bearings.  The
performance index includes improvement of durability, quiet
operation, less vibration, high-speed rotation performance, and
sealability.

      The magnitudes of vibration of ball bearing spindles depend on
the quality of the balls and races, magnitude of the preload,
lubricant type, and the spindle motor.  As long as the above
mentioned parameters are affecting the running accuracy of ball
bearing spindles, it is virtually impossible to reduce non-repeatable
vibrations significantly over today's levels.  On the other hand, a
hydrodynamic bearing has only two bearing surfaces separated by a
viscous fluid, which averages out surface out-of-roundness errors to
produce center error which are only a fraction of the surface errors,
thereby, reducing repeatable vibration and non-repeatable vibrations.

      Various integral hydrodynamic spindle designs have been
proposed.  These integral designs are dedicated designs, thereby
manufactured on small scales.  In contrast, the present invention
provides a generic hydrodynamic bearing unit, which is candidate for
a wide variety of engineering applications including hard disk drive
spindles, thereby potential for large scale manufacturing.

      Demand for high running accuracy, high speeds, high damping
characteristics, and long life for bearings has surged during the
past few years in many industries including hard disk drives, laser
scanners, gyroscopes, etc. Traditional solutions to meet these
requirements use integral hydrodynamic bearing designs, where the
bearing surfaces share the same fluid cavity, the hydrodynamic
surfaces are etched or machined on the elements of the spindle
including the shaft, and the filling of the bearing surfaces with the
lubricant is performed during the assembly process of the spindle.
This practice makes the design application oriented, thus limiting
its use in other applications.

      The proposed unit hydrodynamic bearing uses gas, oil, grease,
or magnetic fluid as the lubricating fluid.  The hydrodynamic bearing
is a self contained unit meaning that the bearing comprises an outer
race, and an inner race.  The bearing surfaces and the lubricant are
enclosed in the space between the inner and outer races.  The bearing
assembly fits as one unit into existing spindle designs composed of a
stator and a rotor...