Rotary magnet has relatively rotatable armature and yoke with off-set working air gaps between same with the overlapping surface of one gap reducing and that of the other increasing during relative rotation

摘要

Rotary magnet has an armature (4) and a yoke (6) rotatable relative to one another about a common longitudinal axis (X). Two working air gaps (26,28) are formed between same off-set relative to each other so that during relative rotation an overlapping surface area of one gap reduces whilst that of the other gap increases. At least one coil (12, 14) and permanent magnet (16) are arranged so that when the coil is energised they produce rectified magnetic fields at one of the gaps and oppositely directed magnetic fields at the other gap. Two coils are spaced from one another in the direction of the longitudinal axis and the permanent magnet is mounted between the two coils.