| 摘要 |
PURPOSE:To generate a slip on contact surface between a back yoke and a rotor yoke for preventing burning of a motor when an excessive load is applied to an apparatus, by bringing said back yoke and rotor yoke hit into contact with each other and by transmitting a rotary driving force to the rotor yoke via said contact surface. CONSTITUTION:When a driving current is caused to flow through a stator winding 3, a rotor magnet 1 and a back yoke 2 integrally start rotation. A rotor yoke 4 is attracted by said rotor magnet 1 so that a pressure is generated in a contact surface A of the rotor yoke 4 and the back yoke 2. Therefore, a rotary driving force proportional to a friction coefficient and a thrust attraction force between the back yoke 2 and the rotor yoke 4 is transmitted to the rotor yoke 4. When an excessive load is applied, the back yoke 2 and the rotor yoke 4 slip on each other.
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