GB1325670A - Axial flow fans the impellar vanes of which are adjustable during operation - Google Patents

Abstract

1325670 Axial-flow fans NORDISK VENTILATOR CO A S 25 June 1971 [10 July 1970] 29998/71 Heading F1C An axial-flow fan has impeller vanes which are adjustable cyclically during an adjusting movement during fan operation. In one embodiment, Fig.1, the vanes 3 have eccentric members 5 which engage a groove 6 in an adjusting disc 7 mounted on a shaft 8 slightly inclined to impeller drive shaft 2. The impeller and disc are rotated with their respective shaft at the same speed. The disc 7 thereby oscillates at a small angle relative to the members 5 but small free-play at groove 6 and material elasticity prevent consequential adjustment of the vanes 3. Impeller vane adjustment is made by axial movement of shaft 8, the inclination of the plate 7 being such that during the axial adjusting movement the vanes are adjusted cyclically so that the pitch of at least one but not all of the vanes is adjusted at a time. The members 5 may instead be connected to the plate 7 by links (15), Fig.4 (not shown), the linkage having the necessary free-play. In another embodiment, Figs.11 and 12, (not shown), the shaft (8) is not rotatable. In Fig.13 (not shown), the plate (7) is mounted on a sleeve located on a fixed shaft (8) for hydraulic adjustment in the axial direction. In other embodiments the vane adjustment is effected by angular adjustment of an inclined plate (7) receiving the eccentric members (5) in axial slots (16), Figs. 5 and 6 (not shown), or connected thereto through links (17), Figs.7 and 8 (not shown). Fig.15 (not shown) displays two impellers mounted on opposite ends of a common hollow driving shaft (35) and each having vanes adjustable by a respective plate carried by an inclined shaft, the two inclined shafts being connected by a universal coupling. In another embodiment, Figs.9 and 10 (not shown), the axis of the adjusting shaft (8) is parallel but eccentric to the impeller shaft axis, and the plate (7) lies perpendicular to shaft (8) and has gear teeth (19) at its periphery in engagement with pinions (18) carried by the impeller vanes. The angle of the inclined adjusting shaft or the spacing of the eccentric adjusting shaft may be regulated; e.g., the eccentricity may be regulated by rotating one eccentric sleeve relatively to another eccentric sleeve.