| 摘要 |
PURPOSE:To enable to reduce sharply the number of rotations for starting floatation, by closing the breather of the thrust portion of a bearing in case of starting, and opening the breather during rotations. CONSTITUTION:Because on opening/closing member 4 is an elastic body, its central vicinity makes contact with a thrust bearing member 12. Thus, a breather 4a is closed up. When rotors 12, 3, 4 rotate, internal pressure in gaps 5a, 5b becomes high so that the rotors 12, 3, 4 float. As the breather 4a remains to be closed up immediately after the rotors 12, 3, 4 started to rotate, the pres sure reduction of fluid streamed into from an arrow A position is prevented. Therefore, flotation time of the rotors 12, 3, 4 becomes earlier and the flotation starts at a low rotational speed, so that the number of rotations can be sharply reduced.
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