US 5,021,698 AGranted

Axial field electrical generator

AssigneeROLLS-ROYCE plc

InventorsKeith R. Pullen, Kevin J. Horton, Mohammad R. Etemad, Arnoldo Fenocchi, Laurence W. Eggleston, Hugh R. Bolton

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Abstract

Potentially very high power ratings can be achieved from rotary electrical generators in which permanent magnet rotor stages using modern high intensity magnetic materials, for example cobalt samarium or neodymium boron iron. The machine described comprises a plurality of axial field rotor stages each comprising a plurality of magnet segments arranged around a driven hub in a pre-stressed assembly in which encompassing hoop means exerts sufficient compressive stress on the magnets and hub assembly to counter centripetal forces generated by speeds of up to 100,000 rpm. Alternative methods of stressing the hoop means is described.

Claims19

Dependent claims

An axial field electrical generator capable of operating at very high rotational speeds comprising:

at least one permanent magnet disc rotor having a plurality of permanent magnet segments equiangularly spaced apart around a hub, said hub containing notches or pockets to engage said permanent magnets and with which engagement is maintained during operation by means of pre-stressed hoop means encompassing the hub and magnets, said pre-stressed hoop means being formed initially as a push fit and stressed during assembly with the hub and magnets by expansion of the hub by forcedly fitting into a central bore of the hub a relatively tapered boss;
and a stator winding spaced a short axial distance from a face of the disc rotor.

Dependencies are inferred from the claim text.

Facts

Application: 07/581,085Filed 12 Sep 1990 · continuation
Priority: GB 881776026 Jul 1988
Granted: 4 Jun 1991
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H02K 1/2796
The rotor consisting of two or more circumferentially positioned magnets: where both axial sides of the rotor face a stator
H02K 1/2798
The rotor consisting of two or more circumferentially positioned magnets: where both axial sides of the stator face a rotor
H02K 15/03
Of stator or rotor bodies: having permanent magnets
H02K 21/24
With stationary armatures and rotating magnets: with magnets axially facing the armatures, e.g. hub-type cycle dynamos