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Improved Thrust Reservoir and Seal Labyrinth for a FDB Spindle Disclosure Number: IPCOM000016029D
Original Publication Date: 2002-Sep-12
Included in the Prior Art Database: 2003-Jun-21

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Disclosed is an improved configuration for the oil reservoir in a fluid dynamic spindle having a classical "spool bearing" configuration. This improved configuration for the thrust reservoir inhibits loss of oil from it in non-operating shock and vibration environments. Figure 1 shows a typical fluid dynamic bearing spindle that has a "spool" configuration. Area A-A shows just one end of this "spool" bearing. Attached to this fluid bearing cartridge is a hub having a rotor magnet that is radially poled. The spindle assembly is completed by a stationary motor winding. This 3 phase winding is DC commutated in a synchronous manner to interact with the magnet rotor, and rotate the hub on its fluid bearing. In the prior spindle art, the surfaces of the thrust bearing oil reservoir are substantially cylindrical. Figure 2 shows the improved configuration for area A-A. In this type of fluid "spool bearing", the spindle shaft (A) is stationary. To it is fixed the upper thrust bushing (B) at an appropriate axial spacing to thrust surface (F) . This spacing is typically on the order of 6 to 8 microns. Shallow groove patterns on either the (B) or (C) side of the thrust gap enhance the ability of the oil liquid to generate a pressure profile when the sleeve (C) is rotated. Continuous and orthogonal to this axial thrust bearing is the upper radial bearing formed at location "E". The radial gap is much smaller typically with a dimension on the order of 2 to 3 microns. Here again the pressure profile is enhanced by a herringbone pattern of shallow grooves. The upper radial bearing and its corresponding axial thrust bearing with it's oil volume typically are physically separate and independent from the corresponding pair at the opposite end of the fixed shaft. 1