Rim drive electrical machine

Abstract

A rim driven electrical machine for interaction with a flow of water, comprising: a rotor mounted within a housing, the rotor including at least one circumferential conductor and a central passageway, the central passageway for receiving at least one blade arrangement for rotational interaction with a fluid within the central passageway, and; a stator supported by the housing and arranged circumferentially around the rotor, the stator including windings for providing a travelling electromagnetic wave for interaction with the at least one circumferential electrical conductor of the rotor, wherein the stator extends only partially around the circumference of the rotor so as to have a first end and a second end separated by an arcuate angle.

1 . A rim driven electrical machine for interaction with a flow of water, comprising:
 a rotor mounted within a housing, the rotor including at least one circumferential conductor and a central passageway, the central passageway for receiving at least one blade arrangement for rotational interaction with a fluid within the central passageway, and;   a stator supported by the housing and arranged circumferentially around the rotor, the stator including windings for providing a travelling electromagnetic wave for interaction with the at least one circumferential electrical conductor of the rotor,   wherein the stator extends only partially around the circumference of the rotor so as to have a first end and a second end separated by an arcuate angle.   
     
     
         2 . A rim driven electrical machine as claimed in  claim 1 , comprising a plurality of stators. 
     
     
         3 . A rim driven electrical machine as claimed in  claim 1 , wherein the circumferential ratio of stator to housing around the rotor is 1:2. 
     
     
         4 . A rim driven electrical machine as claimed in any of  claim 1  wherein the rotor comprises an annular core of ferromagnetic material having external circumferential layers, the layers comprising an environmental enclosure, and the at least one circumferential electrical conductor is positioned between the annular core and the environmental enclosure. 
     
     
         5 . A rim driven electrical machine as claimed in  claim 3 , in which the annular core is provided with circumferentially distributed electrically conductive rotor bars. 
     
     
         6 . A rim driven electrical machine as claimed in  claim 4 , in which the annular core is provided with circumferentially distributed permanent magnets. 
     
     
         7 . A rim driven electrical machine as claimed in any one of  claim 4 , in which the environmental enclosure is made from an electrically conductive material. 
     
     
         8 . A rim driven electrical machine as claimed in of  claim 4 , in which the electrical resistance of the environmental enclosure is higher than that of the or each circumferential electrical conductor. 
     
     
         9 . A rim driven electrical machine as claimed in  claim 1 , wherein the at least one circumferential electrical conductor includes apertures which define circumferentially distributed bars extending substantially in the direction of the axis of rotation of the rotor. 
     
     
         10 . A rim driven electrical machine as claimed in  claim 1 , comprising at least two circumferential electrical conductors, wherein the or each conductor is a sleeve. 
     
     
         11 . A rim driven electrical machine as claimed in  claim 10 , in which the layers are of progressively reducing electrical resistance in the radially inwards direction. 
     
     
         12 . A rim driven electrical machine as claimed in  claim 1 , in which the sleeve immediately adjacent the environmental enclosure is radially thicker than the environmental enclosure. 
     
     
         13 . A rim driven electrical machine as claimed in  claim 1  wherein at least a portion of the housing and rotor are separated by a substantially uniform gap which acts as a bearing surface for the rotor. 
     
     
         14 . A rim driven electrical machine as claimed in  claim 1 , in which the rotor comprises an impeller or turbine having an array of blades secured to and extending inwardly of the annular core. 
     
     
         15 . A rim driven electrical machine as claimed in  claim 1  wherein the stator is located adjacent the lowest part of rotor when in use.