| 摘要 |
PURPOSE:To prevent the excessive rubbing by automatically spreading the gap between an impeller and a stator by fitting a bush which is deformed by the frictional heat into the part of a stator opposed to the top edge of an open type impeller. CONSTITUTION:During operation, an open impeller 1a abnormally approaches in the axial direction to a stator, and the top edge of the blade of an impeller outlet starts slightly rub with the covering member 8' of a bush 7. Though, in this stage, the impeller blade is not damaged, the temperature of the bush 7 becomes higher than the normal operation temperature by the frictional heat in rubbing. At the temperature rise becomes larger, a difference of thermal expansion rate is generated between the basic member 8 of the bush 7 and the covering member 8', and the bush 7 is deformed so as to be bent towards the basic member 8 side, and is separated from the blade of the impeller 1a. Therefore, the process of rubbing can be prevented, and the machine can be protected from being damaged by rubbing, and also the gap between the impeller 1a and the stator can be reduced.
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