SYNCHRONOUS MOTOR

PURPOSE:To prevent a permanent magnet from being damaged due to a centrifugal force, by fitting a non-magnetic reinforcing ring on the outer periphery of the permanent magnet for a rotor element. CONSTITUTION:A reinforcing ring 30 made of non-magnetic substance is fitted on the outer periphery of a ring-shaped permanent magnet 24. The ring 30 is shrinkage-fitted, and a constraining force inward in the radial direction is usually applied to the permanent magnet 24 by the reinforcing ring 30. In this manner, on the operation of a motor, a centrifugal force applied to the permanent magnet 24 is received by the reinforcing ring 30, and accordingly, the permanent 24 is prevented from being damaged by cracks and the like. The reinforcing ring 30 is non-magnetic, and so leakage flux is not generated between the adjacent magnetic poles of the permanent magnet 24, and the end face of the permanent magnet 24 is not interrupted by the ring, and so the magnetic field formed in the direction of the motor axis is not influenced by the ring.