Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1987-10-20
1990-02-20
Salce, Patrick R.
Electrical generator or motor structure
Dynamoelectric
Rotary
29598, 310256, 310261, H02K 124, G11B 1922
Patent
active
049029410
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 structure which supports a disk has an annular recess accommodating a disk-holding magnet whose upper surface is slightly recessed relative to an annular magnetically conductive disk-supporting ridge of the rotor, the cross-sectional shape of the ridge being such as to establish a magnetic disk-holding force of exactly predetermined character, despite tolerance-range variation of the coercive force of the holding magnet employed.
REFERENCES:
patent: 3527969 (1970-09-01), Papst
patent: 4503368 (1985-03-01), Sakamoto
patent: 4701653 (1987-10-01), Merkle et al.
Merkle Alfred
Moosmann Georg
Muller Rolf
Koss, Jr. Theodore J.
Papst-Motoren GmbH & Co KG
Rebsch D. L.
Salce Patrick R.
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