Drive motor for information-storage-disk devices
US4902941A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 20, 1987 |
| Grant date | Feb 20, 1990 |
| Priority date | — |
| Expiry date | Oct 20, 2007 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T29/49012
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A drive unit for direct drive of an information-storage disk comprises a brushless dc external-rotor motor having a permanent-magnet rotor magnet arrangement of considerably reduced axial length. Electrostatic charge is removed from the rotor shaft by a metallic spring element which engages the shaft periphery from within the interior of the rotor housing. An electromagnetic braking arrangement is located interiorly of the housing. The packet of stator plates for the stator has an axial length shorter than that of the rotor magnet arrangement, but is provided at its axial end faces with skirted-rim flux-conducting elements whose peripheral skirt portions form useful-air-gap extensions in cooperation with the rotor magnet arrangement. The stator plate packet and associated skirted-rim flux-conducting elements may have cut-outs defining salient-pole structure, and the skirt portions of the flux-conducting elements be then provided with cut-outs at their leading ends serving to produce a reluctance torque component which, during rotor rotation, is shifted in time relative to the electromagnetic torque component attributable to the salient-pole configuration. The portion of the rotor s…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.