ROTARY SHAFT SEALING STRUCTURE OF DISK DRIVE MOTOR

摘要

PURPOSE:To simplify the sealing structure of a rotary shaft and to improve the revolving accuracy of a rotary shaft by providing a ring to a part of a hub and holding a magnetic fluid in a gap formed between a ring and two sheets of pole pieces fixed to a bearing supporting housing. CONSTITUTION:A soft magnetic ring 24 is fixed at the outer circumference of a cylindrical part which is fitted to a nonmagnetic rotary shaft 23 of a hub 22. Two sheets of pole pieces 25 are fixed to a nonmagnetic housing 29 which supports a bearing 28 to hold a magnet 26. A magnetic fluid 27 is held in a gap formed between the pieces 25 and the ring 24. The span is increased between bearings since the ring 24 is set at a part of the hub 22. This improves the revolving accuracy and also simplifies the sealing structure of the shaft 23.