Quantum Corporation

Yan Zang

Michael R Hatch

Shuo-Hao Chen

Shinichi Minakuchi

Shuhao Chen

A self-contained hydrodynamic bearing unit with improved sealing and performance is disclosed. Centrifugal capillary seals are angularly defined between an outwardly tapered outer surface of a top screw and an inwardly tapered inner surface of an annular clamp ring at the top of the bearing unit as well as between an outwardly tapered outer surface of a seal plate and an inwardly tapered inner surface of an annular clamp ring at the bottom of the bearing unit. During operation, bearing lubricant is pumped away from the seal opening and toward the bearings by centrifugal force at the seals, providing dynamic sealing. When the bearing unit is not rotating, capillary forces retain the lubricant within the seal, preventing the lubricant from leaking. The tapered configuration of the seals also shortens the vertical seal length for a given effective seal length, thereby maximizing the journal bearing length/span and improving dynamic performance of the bearing unit.

Hydrodynamic bearing unit

Particle traps in a hydrodynamic bearing unit prevent particles, generated by repeated motor start and stop operations or lubricant cavitation caused by shock loads or introduced by ambient sources, from circulating with the bearing lubricant, thereby preventing accelerated wear of bearing grooves. Each trap is defined by an annular bevel shaped channel defined along the inner radial wall of a shaft sleeve. Each trap is located in close proximity to hydrodynamic bearings so that existing particles and any wear particles generated by the bearings may be pumped into the traps by centrifugal force created by rotation of the bearing unit and imparted to the lubricant. The centrifuge-like effect forces the particles against the back wall of each channel while the bevel shaped configuration of the channels prevents particles from migrating out of the channels after the motor stops. The configuration and location of the traps eliminate the need for global recirculation of bearing lubricant, thereby reducing the risk of leakage.

Hydrodynamic bearing having lubricant particle traps

A self-contained hydrodynamic bearing unit includes a shaft having a threaded axial opening at one end thereof and a shaft shoulder adjacent the opening and perpendicular with a longitudinal axis of the shaft, a sleeve defining an opening for receiving the shaft for relative rotation, a pair of longitudinally spaced-apart radial hydrodynamic journal bearings defined between the shaft and the sleeve, a shaft-bolt including a threaded end region for mating with the threaded axial opening of the shaft and defining a bolt shoulder, an annular thrust plate having two parallel radial faces and adapted to fit upon the shaft-bolt for mounting between the shaft shoulder and the shaft bolt shoulder when the shaft-bolt is mated with the threaded axial opening of the shaft, the sleeve defining a radial thrust bearing surface portion extending radially outwardly at one end and positioned to confront one radial face of the thrust plate, an annular thrust bushing mounted to the sleeve and defining a radial thrust bearing surface portion confronting the other radial face of the thrust plate, the annular thrust plate defining two axial hydrodynamic thrust bearings respectively with the radial thrust bearing surface portion of the sleeve and the radial thrust bearing surface portion of the annular thrust bushing and a hydrodynamic thrust bearing lubricant reservoir between the two axial hydrodynamic thrust bearings and between a cylindrical face of the thrust plate and a facing cylindrical wall of the sleeve, and a hydrodynamic bearing lubricant in the bearing unit and at the pair of hydrodynamic journal bearings and at the two axial hydrodynamic thrust bearings and in the hydrodynamic bearing lubricant reservoir.

Hydrodynamic bearing for spindle motor having high inertial load

A self-contained hydrodynamic bearing unit includes a shaft and a shaft housing defining an opening for receiving the shaft for relative rotation. The shaft and bearing define at least one radial hydrodynamic bearing and an annular thrust bearing, formed as a disk portion extending radially outward of a main cylindrical surface of the shaft which cooperates with an adjacent annular face of the shaft housing. A gap between an outer cylindrical wall of the thrust bearing disk portion and an adjacently facing cylindrical surface of the shaft housing provides a primary annular capillary seal segment. An annular bushing ring extends from the housing radially inwardly to enclose the thrust bearing disk, and cooperates with an adjacent outer face of the thrust bearing disk to provide a secondary containment capillary seal segment. Normally, lubricating liquid is in the bearing unit at the radial hydrodynamic bearing, at the hydrodynamic thrust bearing and in the primary annular capillary seal segment. However, if liquid overflows from, or extends beyond the primary seal segment as by thermal expansion, it is contained in the secondary seal segment and urged to return by centrifugal force to the primary seal segment. A tertiary containment seal may also be provided to prevent escape of liquid to the external ambient.

Self-contained hydrodynamic bearing unit and seals

A seal for a hydrodynamic bearing unit having a shaft and a sleeve includes a seal ring secured to the shaft and extending radially outwardly of the pair of spaced-apart hydrodynamic journal bearings defined between the seal ring and a thrust plate. The seal ring adjacently faces adjacent radial and axial portions of the sleeve. An annular taper capillary seal is defined between a diverging outer wall surface of the seal ring and the adjacent axial portion of the sleeve. A containment ring extends from the sleeve to surround a radial wall portion of the seal ring adjacent to an opening of the taper capillary seal and forms a secondary containment seal opening toward the shaft for preventing escape of the hydrodynamic bearing lubricant. The hydrodynamic lubricant is placed within the annular taper capillary seal and is retained in place by capillary force in the absence of rotation, and is retained in place by capillary force and by centrifugal force in the presence of relative rotation between the shaft and the sleeve.

Shaft seal for hydrodynamic bearing unit

A hydrodynamic bearing unit includes a shaft, a sleeve rotatably disposed over the shaft and defining a plurality of spaced-apart hydrodynamic journal bearings, an annular axial thrust plate secured to the shaft to form a shaft subassembly and having a first radial surface in facing confrontation with a shoulder of the sleeve and defining a first hydrodynamic thrust bearing, a thrust bushing secured to the sleeve to form a sleeve subassembly and having a bearing surface in overlying facing engagement with a second radial surface of the annular axial thrust plate to form a second hydrodynamic thrust bearing, a seal for hydrodynamic lubricant defined within an annular Vee groove located adjacent to the shaft and having an apex converging toward the second hydrodynamic thrust bearing, a motor for rotating the sleeve subassembly relative to the shaft subassembly, and hydrodynamic lubricant within the annular Vee groove, the lubricant being retained in place by capillary force in the absence, of rotation, and by centrifugal force in the presence of relative rotation between the subassemblies. A secondary seal is also described.

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Milpitas, CA, United States of America

Yan Zang