| 摘要 |
PURPOSE:To enable sufficient rigidity to be stably maintained, by forming the upper edge, provided in the downstream side with respect to and extended in a direction crossing with the rotary direction, of a bearing force generating groove to a circular arc shape. CONSTITUTION:A peripheral surface 10 of a bearing force generating member 7 provides a plurality of long and narrow grooves 11, extended along a direction B crossing with the rotary direction A of a rotary shaft 6, almost in an equal distancewith respect to the peripheral direction. Further the peripheral surface 10 provides grooves 12 of large width in a depth smaller than that of the groove 11 continuously corresponding to the groove 11 further in the downstream side with respect to the rotary direction A. And the member 7 forms with respect to the rotary direction A of the rotary shaft 6 a boundary part, between the peripheral surface 10 of the bearing force generating member 7 following to the groove 11 and the groove 11, and a boundary part, between the groove 11 and the groove 12 following to the groove 11, smoothly to a circular arc shape.
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