Seagate Technology Incorporated

Digital Equipment Corporation

Coda H Pan

Hans L Leuthold

Gunter Karl Heine

Raquib Uddin Khan

David John Jennings

Wesley R Clark

Lakshman Nagarathnam

Yiao-Tee Hsia

A hydrodynamic bearing design is disclosed incorporating a flexible membrane at one end of the fluid gap in the hydrodynamic bearing. If voids exist in the fluid, and if changes in the size of these voids or bubbles occur with changes in temperature or pressure in which the disc drive is being used, then the volume of the fluid will change, and increase relative to the change in size of the volume of the surrounding physical part. The flexible membrane will yield to the increased pressure of the increasing volume of the fluid. The membrane essentially acts as a spring whose spring force is overcome by the pressure created by or accompanying a increase in volume in which the lubricating fluid is contained, and preventing its escape or being forced out of the inner region of the bearing.

Fluid retention principle for hydrodynamic bearings

A hydrodynamic bearing incorporates a flexible membrane at one end of the fluid gap in the hydrodynamic bearing. If voids exist in the fluid, and if changes in the size of these voids or bubbles occur with changes in temperature or pressure in which the disc drive is being used, then the volume of the fluid will change, and increase relative to the change in size of the volume of the surrounding physical part. The flexible membrane will yield to the increased pressure of the increasing volume of the fluid. The membrane essentially acts as a spring whose spring force is overcome by the pressure created by or accompanying a increase in volume of the fluid. As this happens, the spring force of the membrane is overcome, the membrane relaxes and forms a bladder, effectively increasing the volume in which the lubricating fluid is contained, and preventing its escape or being forced out of the inner region of the bearing. In this way, the fluid remains in the bearing and will not enter the surrounding atmosphere, nor will it be lost from the journal bearing region so that the hydrodynamic bearing is not as effective, when the temperature decreases or the pressure drops.

Fluid retention principles for hydrodynamic bearings

A slider that moves a transducer across a surface of a rotating storage disk includes an island that protrudes from a surface of a subambient pressure cavity for supporting the transducer, the island having length and width dimensions that are less than those of the slider. A groove is positioned at the forward end of at least one of the side rails that define the cavity to allow air to flow between the cavity and an area outside of said cavity. The groove serves to maintain the distance between the surface of that rail and the disk surface equal to the distance between the surface of the other rail and the disk surface as the slider moves across the disk. The rail includes a plurality of grooves for equalizing the flying heights of the rails; a first one of the grooves intersects the cavity to allow air to flow between the cavity and an area outside of the slider, while and a second one of the grooves is spaced from the cavity by a portion of the rail.

Subambient pressure air bearing slider for disk drive

A self-lubricating hydrodynamic spindle bearing for support of a spindle of a magnetic disk drive assembly includes a crankcase design which provides large reservoirs for oil storage with an air cover in communication with the ambient environment through an air vents provided by clearance seals formed between respective central passages of housing-sealing endcaps and the shaft. The crankcase reservoir volume is defined within the bearing so that natural body force effects cause the lubricant to be fed into the hydrodynamic bearing. A leak-preventing capillary trap of minimal continuous axial length may be provided at the clearance seal for passive capture of wandering lubricant when the bearing is at rest. Full evacuation of lubricant trapped at the clearance seal is achieved toward the interior of the housing by centrifugal pumping, e.g., the inboard side of the rotating part of the seal is coned and fluted such that the rotating centrifugal field will throw all statically trapped oil into the lubricant reservoir. A three way restrictive valve is provided to assure balanced feeding of lubricant to both ends of the spindle for either vertical or horizontal spindle orientation. A pressure-actuated bladder may be attached to the bearing to deliver a volume of lubricant to the bearing on demand.

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Millbury, MA, United States of America

Coda H Pan