Seagate Technology Incorporated

Lakshman Nagarathnam

Hans L Leuthold

David John Jennings

Gunter Karl Heine

Raquib Uddin Khan

Wesley R Clark

Norbert Steven Parsoneault

Coda H Pan

Alan Lyndon Grantz

Dean Albert Tarrant

Steve G Gonzalez

Steve Parsoneault

Gunther Heine

Greg Rudd

Hydrodynamic bearing having a shaft relatively rotatable with respect to a surrounding sleeve and having a thrust plate on one end thereof rotating in a recess of the sleeve. The shaft is preferably interrupted by a equi-pressure groove accessing a central reservoir in the shaft and having journal bearings defined by herringbone patterns above and below the groove to stabilize and provide stiffness to the cartridge. The stiffness of the cartridge is further enhanced by a thrust plate carried at one end of the shaft and rotating in a recess of the sleeve and being used to define thrust bearings on either surface thereof.

Single plate hydrodynamic bearing cartridge

A spindle motor is described having a motor stator, a motor rotor, the motor being energized to cause rotation of the rotor supporting a single disc or a stack of discs which is mounted in such a way that the rotating bottom or top (or both) disc surface is closely adjacent to a stationary disc drive casting surface. The squeeze film action in the remaining air gap provides significant damping of the disc vibration. Typical implementation use air gaps of 0.004&Prime;-0.006&Prime; for 2&frac12;&Prime; drives and 0.006&Prime;-0.10&Prime; for 3&frac12;&Prime; drives.

Squeeze film damping for a hard disc drive

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 thrust plate with grooved surfaces within a hydrodynamic bearing establishes pressure gradients which cause the lubricating fluid for the bearing to reliably remain within the region of the hydrodynamic bearing, with the pressure gradient imposed on the fluid causing the fluid to flow toward the center of the bearing rather than to be caused to be forced outward toward the far end of the bearing which could potentially result in a leakage of the fluid.

Single plate hydrodynamic bearing with self-balancing fluid level

Sinusoidal grooving pattern for grooved journal bearing

A self-lubricating hydrodynamic spindle bearing comprising a stationary shaft including a conical, inwardly tapered surfaces extending axially form outer regions of the shaft toward a center connecting region of the shaft, a rotatably mounted sleeve surrounding the shaft and including surface regions flared axially inwardly toward a center region of the sleeve, the tapered surface regions and the flared surface regions defining a bearing gap for the hydrodynamic bearing, the sleeve defining a connection region adjacent the connecting region between the tapered surfaces of the shaft, the connection region including a tube collapsible in response to a change in internal pressure in the connection region to stabilize stiffness and power consumption in the bearing.

Hydrodynamic bearing with reduced temperature sensitivity

A spindle motor includes a rotating hub for supporting one or more discs in a disc drive, and a hydrodynamic bearing system for supporting a hub for rotation, the bearing system includes a sleeve and a shaft fitted into an axial bore of the sleeve. The shaft and the sleeve rotate freely relative to one another, and together, define a journal bearing. The shaft supports an annular thrust plate. The thrust plate extends into a recess formed by an axial face stepped into the sleeve and a counterplate parallel to the axial face and the thrust plate and attached to the sleeve. A first surface of the thrust plate faces the axial face of the sleeve which has a groove pattern formed on it. A surface of the counterplate faces an opposed, second surface of the thrust plate which has a groove pattern formed on it, to form an effective fluid pumping system in the hydrodynamic bearing.

Hydrodynamic bearing assembly with single sided grooved counterplace

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.

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Capitola, CA, United States of America

Lakshman Nagarathnam