| 摘要 |
<p>1,216,703. Axial-flow fans. NORDISK VENTILATOR CO. A/S. Jan. 26, 1968 [Jan. 30, 1967], No. 4334/68. Heading F1C. [Also in Division F4] A fan for ventilating buildings comprises a cylindrical intake duct 9 fitted coaxially around a cylindrical exhaust duct 8, air being impelled in opposite directions through the two ducts by respective impeller vanes 3, 2 driven by a common motor 1. When respective dampers 19, 14 movable axially through a common control rod 16 by a motor 17 are open, air is drawn into the intake duct 9 through an opening 25 above the roof 22 and is discharged below the celling 21 through twelve nozzles 10, while air entering the exhaust duct 8 at 13 is discharged at 26. When the dampers 19, 14 are moved downwardly to close the lower ends of the ducts 9, 8, the resultant occurrence of a gap between the damper 14 and an impeller shroud 5 provides an inter-connection between the ducts. The nozzles 10 can be individually throttled by means of guide vanes 30.</p> |
