Flat brushless dc motor

Abstract

Abstract PURPOSE:To reduce a friction torque between a shaft and a bearing by leading leakage fluxes from protrusion parts of permanent magnets to an auxiliary yoke to reduce the magnetic attraction between the magnets and a plate-like yoke. CONSTITUTION:Protrusion parts 6a engaged with holes 5a provided in a magnet side yoke 5 are formed on magnets 6 of a rotor 3. Poles 10 are set up at the four corners of a plate-like yoke 8 of a stator 7 and an auxiliary yoke 11 is supported by the poles. Hereupon, magnetic fluxes phi1 from south poles of the magnets 6 reach north poles of the magnets 6 through an armature coil, the plate-like yoke 8 and the armature coil. Further, the magnetic fluxes phi1 pass through the gap 17 between the magnet 6 and the auxiliary yoke 11, the auxiliary yoke 11 and the air gap 17. In such a manner, since the magnetic fluxes from the protrusion parts of the permanent magnets are led to the auxiliary yoke, magnetic suction forces are generated in the direction from the magnets to the auxiliary yoke, magnetic suction forces in the direction from the magnets to the plate-like yoke are reduced and a friction torque between a shaft and a bearing can be reduced. Thereby, the abrasion of a motor is avoided as well as the reduction of the output power of the motor can be prevented.

Inventors

• 👤 Hiroo Takano
• 👤 高野　博夫

Bibliographic Details