| 摘要 |
A spindle motor ( 50 ) is composed of a base ( 8 ), a sleeve ( 4 ) in cylindrical shape that is fixed on the base ( 8 ), a shaft section ( 1 ) inserted into a through hole ( 4 b) of the sleeve ( 4 ) that is rotatable with respect to the base ( 8 ), a hub ( 7 ) that rotates together with the shaft section ( 1 ), a radial dynamic pressure bearing section (RB) formed between a bushing ( 13 ) and the sleeve ( 4 ), a flange section ( 4 a) that protrudes in a radial direction on an outer circumferential section of the sleeve ( 4 ), a wall section ( 7 a) in annular shape that protrudes with surrounding the sleeve ( 4 ), a thrust ring ( 3 ) that is fixed on an inner circumferential section of the wall section ( 7 a) being adjacent to the flange section ( 4 a) and the bushing ( 13 ) in an axial direction, and a seal plate ( 17 fixed on an outer circumferential section of the sleeve ( 4 ) with sandwiching the thrust ring ( 3 ) between the flange section ( 4 a) of the sleeve ( 4 ) and the seal plate ( 17 ) in an axial direction. The spindle motor ( 50 ) is furnished with a first thrust dynamic pressure bearing section (SB 1 ), which is formed between confronting surfaces ( 3 a , 4 a 1 ) of the thrust ring ( 3 ) and the flange section ( 4 a), and a second thrust dynamic pressure bearing section (SB 2 ), which is formed between confronting surfaces ( 3 b , 17 a) of the thrust ring ( 3 ) and the seal plate ( 17 ).
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