PURPOSE: To hardly be affected by impact and vibration even when large impact and vibration due to external force is applied.
CONSTITUTION: In a drive motor in which a first permanent magnet 11 is attached to a lower end of a rotary sleeve 4, and a second permanent magnet 12 is fixed to a housing 1 in the direction so that the same kind magnetic poles as the first permanent magnet 11 are confronted with each other in the vertical direction, and a rotary sleeve 4 is floated by repulsion force of magnetism, and an air collection 13 is formed between the cover 3 of the upper end of the rotary sleeve 4 and a fixed shaft 2, ring-shaped grooves 15, 16 are provided in the vicinity of the upper end and on the upper side position of the first permanent magnet 11 on the outer peripheral surface of the fixed shaft 2. Then, when large impact and vibration are applied to a device, and air in the air collection 13 flows out from a gap between the fixed shaft 2 and the rotary sleeve 4 or the air flows into the air collection 13 from the outside, the flow of the air is prevented, and the lowering of a damper effect is prevented.
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UZUKI KAZUO
SUZUKI YASUO
TOMITA KENICHI
SAIKAWA SHIZUKA
