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Disk driving motor
| Details |
Inventors: Ishizuka, Yutaka; Kinoshita, Shinji;
Assignee: Kabushiki Kaisha Sankyo Seiki Seisakusho (Nagano, JP)
Primary Examiner: Hannon; Thomas R.
Assistant Examiner:
Attorney, Agent or Firm: Sughrue, Mion, Zinn, Macpeak & Seas
A magnetic disk driving device includes a frame which supports a shaft, a hub adapted to hold a disk, and upper and lower bearings which are fitted in a bearing holding hole and rotatably support the hub. The frame includes a cylindrical protrusion which is confronted through a small gap d with the outer cylindrical surface of the outer race of the lower bearing. The small gap d forms a labyrinth in the space through which the inside of the lower bearing is communicated with the outside. The inner cylindrical surface of an annular protrusion formed on the bottom of the hub, and the inner cylindrical surface of the cylindrical protrusion are substantially equal in diameter. |
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DETAILED DESCRIPTION In view of the foregoing, an object of the invention is to provide a disk driving motor in which the flow of dust or the like is blocked which comes from the lower bearing through the small gap, whereby a rotor such as a disk is prevented from being adversely affected thereby.
Another object of the invention is to provide a disk driving motor in which the seal mechanism is formed at low cost, and which is small in size as a whole.
A further object of the invention is to provide a disk driving motor in which its rotor is improved in the balance of rotation, and which is suppressed in the production of noise, and is improved in oscillation characteristic.
Accoring to an aspect of the present invention, there is provided a disk driving motor comprising: a shaft; a frame supporting said shaft; a hub on which a disk is mounted, said hub having a bearing holding hole; and a ball bearing having an inner race mounted on said shaft, and an outer race fixedly fitted in said bearing holding hole of said hub, thus rotatably supporting said hub, said frame includes a protruded annular bank which is confronted through a small gap with the outer cylindrical surface of said outer race of said ball bearing, and the inner cylindrical surface of said protruded annular bank is approximately larger by (2.
times.
d) in diameter than the inner cylindrical surface of said bearing holding hole of said hub, where d is the width of said small gap.
As was described above, in the disk driving motor of the invention, the small gap formed between the inner cylindrical surface of the protruded annular bank of the frame and the outer cylindrical surface of the outer race of the lower ball bearing, is utilized to isolate from each other the first space communicated with the inside of the bearing and the second space communicated with outside, so that the flow of dust from the insides of the upper and lower ball bearings is blocked.
Furthermore, in the motor of the invention, the inner cylindrical surface of the protruded annular bank of the frame, and the inner cylindrical surface of the bearing holding hole of the hub are substantially equal in diameter to each other with the small gap between them
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Generators or Motors 
