| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce the occupancy space by occupying the major part of the dimension in the axial direction for a stator winding and a motor magnet cooperated therewith in the space continuously surrounded with a disk supporting part. SOLUTION: A boss 64 is arranged adjacent to an end surface wall 17A of an external rotor cup 17 and provided with an end surface wall 64A, with which a bearing bush 65 of a shaft 32 is integrally formed. A control magnet 45 is arranged in the axial direction with the motor magnet 13 and provided at the position far away from the end surface 17A of the magnet 13. A magnetic fluid seal 72 comprises two annular magnetic pole pieces 73, 74, a permanent magnet ring 75 positioned between two of these magnetic pole pieces, and a magnetic fluid put between the magnet ring 75 and a part of the shaft 32. The occupancy space is reduced in such a manner that the magnetically operating stator part and the rotor part are arranged inside the space 46 surrounded with the disk supporting part 66 so as to occupy more than 2/3 of the dimension in the axial direction.</p> |
