| 摘要 |
PROBLEM TO BE SOLVED: To provide a spindle motor with a magnetic seal so that a magnetic fluid does not splash even during high speed rotation and a hard disc is never contaminated with the magnetic fluid. SOLUTION: In the spindle motor provided with a shaft 2, a bearing 4 loaded to the shaft 2, a rotor hub 3 supported for relative rotation against the shaft 2 via the bearing 4 and a magnetic fluid seal 5 between the shaft 2 and the rotor hub 3, the magnetic fluid seal 5 includes an annular permanent magnet 51 fixed to the shaft 2, an annular magnetic material fixed to the rotor hub 3 against the permanent magnet 51 via a fine gap in the radius direction, and a magnetic fluid to be filled between the permanent magnet 51 and annular magnetic material 52.
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