| 摘要 |
PURPOSE:To improve dynamic rotational accuracy and durability by adopting power to be generated by a fixed shaft and dynamic pressure generation grooves formed on a rotational body rotatable therearound. CONSTITUTION:A spiral groove for generating dynamic pressure are formed on an outer diametral face 1 of a fixed shaft 10 whose one end is fixed to a substrate 50 and the other is free end, extendingly over the substantial whole length thereof. The fixed shaft 10 is inserted in a rotational body 20 composed of a bottom 22 and a cylindrical member 24, with the free end of the shaft located upside. When the rotational body 20 is driven, gas therearound descends owing to the action of the dynamic pressure generation grooves 12, and the like flows to a pressure chamber 44, and afterward to the outside of the rotational body 20 through a shaft hole 28 of a baring 22. |
