Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1996-03-18
1998-02-10
Stephan, Steven L.
Electrical generator or motor structure
Dynamoelectric
Rotary
310261, 310114, 428 65, 74572, H02K 702
Patent
active
057172633
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to rotors especially rotors constructed from a fibre reinforced composite material.
Rotors may be constructed from fibre reinforced composites. Such rotors may be employed for example in electric motors and/or generators. In such applications the fibres of the composite may be wound helically or in hoops to give the construction appropriate mechanical properties.
In some applications it may be desirable for the rotor to be employed as a motor/generator or to be controlled electromagnetically as part of a machine and therefore the rotor may incorporate magnetic material or material which is influenced by a magnetic field.
According to the present invention a rotor comprises a cylindrical structure including a portion made from a fibre reinforced composite wherein filler material is incorporated within the matrix of the composite and wherein the loading of the filler material varies through the matrix whereby the average mass per unit volume of the structure decreases with distance radially from the axis of the structure, characterised in that the filler material is a magnetic filler material and the loading of the magnetic filler material varies smoothly through the matrix.
The said cylindrical structure may comprise a tubular configuration wherein the mass per unit volume decreases radially from the inner surface to the outer surface of the tube.
There is a difference in rotational speed between the outer surface and the inner surface of a tubular rotor. This causes a corresponding difference or mismatch in strain. By having a magnetic material loading gradient through the composite material from inner to outer surface of the said portion in accordance with the present invention the internal regions of the rotor structure may be designed to strain more at speed because of the higher loading than without the loading. At the outer regions of the said portion of the rotor structure where the magnetic material loading is low the strain will be minimal. In this way, the strain at the inner regions of the said portion of the rotor structure may be matched by the metal loading gradient to the strain at the outer regions. The whole magnetic material loaded composite rotor structure according to the present invention may therefore be operated in a strain matched manner. This allows greater tolerance of the rotor structure to stress cycling.
The said portion may be one or more tubular layers in a multi-layer tubular structure or it may itself comprise substantially the body of a tubular structure.
The composite of the rotor according to the present invention may be one of the known composites employed in the manufacture of rotors or known to be suitable therefor. Thus, the composite may comprise fibres selected from one or more of carbon, glass, boron, polyamide, polyaramid, polyolefin and the matrix material may comprise a cold setting and/or thermosetting and/or thermoplastic polymeric material eg selected from one or more of epoxy resins, polyester resins, Friedel Crafts resins, polyimides, polyether sulphones and polyether ketones (PEEK) optionally together with known additives, hardeners, fillers and the like. The fibres may be wound helically and/or in hooped fashion within the composite in a known way. Different layers may be wound in different configurations, eg in different helical senses. The fibres in each layer of fibres may be wound singly or as a collection of fibres within the composite, eg as tows.
The magnetic material employed in the loading of the composite material in the rotor according to the present invention may comprise particles, spheroids, whiskers, fibres or the like. Desirably, the material comprises powdered material. The magnetic material may comprise iron, nickel, cobalt or an alloy containing one or more of these. It may comprise a ferrite, eg barium ferrite. Alternatively, it may comprise a known hard magnetic material comprising a rare earth element, eg cobalt-samarium or neodymium-boron.
The magnetic material may suitably be incorporated in spaces bet
REFERENCES:
patent: 4188907 (1980-02-01), Lipani
patent: 4444550 (1984-04-01), Loubier
patent: 5021698 (1991-06-01), Pullen et al.
patent: 5124605 (1992-06-01), Bitterly et al.
Scientific American, R.P. Post and S.F. Post, "Flywheels", see p. 21, and figures 3-5 and 8, Dec. 1973.
Proceedings of the 27th Intersociety Energy Conversion Engineering Conference, vol.4, Design and manufacturing for acomposite multi-ring flywheel., see p. 446, left col., Aug. 1992.
British Nuclear Fuels PLC
Stephan Steven L.
Williams Timothy A.
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