| 摘要 |
PURPOSE:To prevent sufficiently the invasion of dust through gaps into the interior of a machine by a method wherein members at the upstream side of a part where seal air is blowing into the surface of a flow path is arranged at the outer peripheral side of the members at the downstream thereof and the gap between both end faces of a hub is slanted toward the backwash of the fan. CONSTITUTION:The diameters D1, D2 of inner tubes 6, 7 are constituted so that a relation Dh1<D1, D2<Dh2 can be established between the diameters Dh1, Dh2 of the end faces of the suction and delivery sides of the impeller hub 2 and the diameters D1, D2 of the suction side inner tube 6 and the delivery side inner tube 7. On the other hand, the fan is constituted so that the members at the upstream side of the part where the seal air is blowing into the surface of the flow path of the hub 2 are arranged at the outer peripheral side of the members at the downstream side thereof. According to this method, the gaps 8, 9 of both end faces of the hub, through which the seal air is blowing out, is shaped so as to be slanted toward the backwash side, the air is blown out under being slanted toward the backwash side and forms the layer of streams along the surface of the flow path since it is pushed by the stream of gas forming a main stream. As a result, possibility of invasion of the dust in the gas through the gaps 8, 9 into the interior of the machine may be reduced remarkably. |
