Electromagnetic rotary vibrator for a rotary body

An electromagnetic rotary vibrator for vibrating a rotary body that is supported by bearings, comprising:

• a ring-shaped magnet which is bipolarly magnetized and which is to be mounted coaxially on a shaft of the rotary body;
• a ring-shaped stator having a coil, wherein said stator is mounted adjacent to said magnet, and wherein the distance between a location of a magnetic pole in said stator and an axis of the shaft is different than the distance between a location of a magnetic pole in said magnet and the axis of the shaft;
• and
• a frequency-variable power source which controllably supplies said coil with AC power, thereby generating a rotating magnetic field, whereby said rotating magnetic field interacts with a magnetic field produced by said magnet such that repulsive electromagnetic forces and attractive electromagnetic forces are exerted between said ring-shaped magnet and said ring-shaped stator;
• wherein the exertion of the repulsive electromagnetic forces and the attractive electromagnetic forces between said ring-shaped magnet and said ring-shaped stator combine to produce a rotational exciting force which is applied to the rotary body.