PURPOSE: To improve the accuracy of arrangement of permanent magnet pieces, to enhance the accuracy of balance at the time of revolution and to stabilize magnetic distribution characteristics by disposing a plurality of the permanent magnet pieces on the outer circumference of a yoke member and arranging elastic bodies pushing the permanent magnet pieces in the circumferential direction at every permanent magnet piece constituting one magnetic pole.
CONSTITUTION: Projecting sections 13 are formed to a yoke 4, and positioned among magnetizing polarity N, S poles attached to magnet pieces 3. Elastic bodies 17 are inserted among air gaps formed by the projecting sections 13 and the magnet pieces 3 are pushed in the circumferential direction, and held so that no clearance is shaped between the magnetic pieces 3a-3b and 3c-3d. Accordingly, the lowering of magnetic distribution at the central section of a magnetic pole can be prevented, and the reference positions of permanent magnet pieces can be set stably, thus improving balance accuracy at the time of revolution.
TOYOSHIMA HISANORI
ISHII YOSHITARO
KAWAMATA MITSUHISA
MIYASHITA KUNIO
OHARAGI HARUO
TAWARA KAZUO
ABE TAKASHI
