Magnetic reduction device

A magnetic reduction device comprising:

• a base portion;
• a rotor rotatably supported relative to the base portion, and supporting first permanent magnets having different polarities alternatively arranged in a circumferential direction;
• a magnet support portion supporting second permanent magnets having different polarities alternatively arranged in the circumferential direction, the second permanent magnets being arranged concentrically with the first permanent magnets;
• and
• a soft magnetic body support portion supporting soft magnetic bodies arranged between the first permanent magnets and the second permanent magnets along the circumferential direction, and being in non-contact with the rotor and the magnet support portion,
• wherein
• one of the magnet support portion and the soft magnetic body support portion is rotatable relative to the base portion,
• the other of the magnet support portion and the soft magnetic body support portion is non-rotatable relative to the base portion, and
• the magnetic reduction device comprises first and second sensors respectively facing the first and second permanent magnets at positions spaced radially outward from an axis of rotation of the rotor, and the first and second sensors for detecting a rotational phase difference between the rotor and the magnet support portion.