Brushless DC motor for hard disc drive - has magnetically-conducting separating rings between magnetic discs mounted on drive hub coupled to rotor

摘要

The brushless DC motor includes an inner stator, which has a stator winding and a winding core. An outer rotor has a rotor housing, which carries a permanent magnet system at its inner surface. A driving hub (24) of magnetic conducting material is provided for mounting several magnetic discs (40) and is connected rotation-proof with the outer rotor, and has at least one distance ring (30) arranged between adjacent magnetic discs on the driving hub. The distance ring or rings are mfd. of magnetic conducting material. The distance ring or rings can be mfd. from nickel plated steel. The distance ring(s) can have a layer of plastics material. ADVANTAGE - Sufficient screening of stray flux with smallest possible redn. of hub vol. using magnetically conducting distance ring(s).