Patent ID: 7170212
Filing Date: 2007-01-30
Classification: H02K

Abstract:
1. A synchronous axial field electrical machine comprising a first substantially planar member ( 9 , 10 ) and a second substantially planar member ( 3 ) arranged substantially parallel to the first substantially planar member, the first and second members being rotatable relative to each other about a common axis substantially perpendicular to the planes of the first and second members wherein the first member ( 9 , 10 ) is provided with an annular array of magnets ( 7 , 8 ) coaxial with the common axis and configured to provide a substantially axial magnetic field passing through the second member and the second member is provided with a first annular array of flat coils ( 1 ) coaxial with the common axis and arranged substantially side-by-side in a first layer and with a second annular array of flat coils ( 2 ) coaxial with the common axis and arranged substantially side-by-side in a second layer, the coils ( 2 ) of the second array being offset in a circumferential direction relative to the coils ( 1 ) of the first array by an amount corresponding substantially to the pitch of adjacent coils divided by the number of layers.