Hydrodynamic bearing having lubricant particle traps

Abstract

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.