Patent ID: 7084548
Filing Date: 2006-08-01
Classification: H02K

Abstract:
1. A high speed brushless axial gap air core electrical machine for converting between electrical and mechanical energy comprising: a rotor mounted for rotation about an axis of rotation, and a stator that is stationary and magnetically interacts with said rotor; said rotor comprising two discs, each having a solid center, free of a through hole, and made substantially entirely of steel, said discs are axially spaced apart to form an armature airgap; a stationary air core armature located in said armature airgap with windings for providing energy conversion; at least one of said discs comprising a circumferential array of multiple alternating axial polarity permanent magnet poles facing said armature airgap that drive magnetic flux circumferentially through said ferromagnetic portions and axially through said armature airgap; said discs further comprising an integral axially extending circumferentially continuous lip outside of said circumferential array of multiple alternating axial polarity permanent magnet poles, said lip having a integral shear connection with said disc that substantially reduces the hoop stress in said lip that would otherwise occur from the radial containment of said circumferential array of multiple alternating axial polarity permanent magnet poles when rotated to high speed.