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Hybrid Air/oil bearing Spindle

IP.com Disclosure Number: IPCOM000012975D
Original Publication Date: 2000-Dec-01
Included in the Prior Art Database: 2003-Jun-11
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Abstract

Disclosed is a novel spindle motor design for high speed DASD applications. The disclosed design incorporates an oil lubricated thrust bearing to carry the axial load and an air lubricated journal bearing to support the radial load. The use of an air radial bearing helps reduce the spindle power consumption at high rotational speeds. This design, referred to as a hybrid bearing motor, offers several advantages over the conventional ball bearing motor designs. First and foremost, it has a lower power consumption than the ball bearing design. Moreover, a hybrid spindle offers very low acoustic emission. Because of its lack of ball bearing defect frequencies, the hybrid motor is expected to have superior NRRO. The low NRRO is critical to implementation of high TPI files in the next DASD generation. As shown in the figure, the thrust plate carrying the axial load has Herringbone grooves on both sides. During rotation, oil is pumped into the gap between the thrust plate and the opposing surface, thus causing separation of the two. The oil leakage is not a concern in this design since the oil is being pushed out towards the OD by the centrifugal force. Similarly, the air journal bearing has Chevron patterns at the top and bottom locations. The grooves cause a pressure build-up in the micron range gap between the rotating and stationary members. Because of air's low viscosity, the radial stiffness is lower than that of an oil lubricated design. However, as mentioned above, the power consumption is improved considerably. 1

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Hybrid Air/oil bearing Spindle

   Disclosed is a novel spindle motor design for high speed DASD applications. The disclosed design incorporates an oil lubricated thrust bearing to carry the axial load and an air lubricated journal bearing to support the radial load. The use of an air radial bearing helps reduce the spindle power consumption at high rotational speeds.

   This design, referred to as a hybrid bearing motor, offers several advantages over the conventional ball bearing motor designs. First and foremost, it has a lower power consumption than the ball bearing design. Moreover, a hybrid spindle offers very low acoustic emission. Because of its lack of ball bearing defect frequencies, the hybrid motor is expected to have superior NRRO. The low NRRO is critical to implementation of high TPI files in the next DASD generation.

   As shown in the figure, the thrust plate carrying the axial load has Herringbone grooves on both sides. During rotation, oil is pumped into the gap between the thrust plate and the opposing surface, thus causing separation of the two. The oil leakage is not a concern in this design since the oil is being pushed out towards the OD by the centrifugal force. Similarly, the air journal bearing has Chevron patterns at the top and bottom locations. The grooves cause a pressure build-up in the micron range gap between the rotating and stationary members. Because of air's low viscosity, the radial stiffness is lower than that of an oil lubricated de...