GB704440A - Improvements in or relating to axial flow fans - Google Patents

Abstract

704,440. Axial-flow fans. BERRY, F. J. B. April 15, 1952 [Nov. 6, 1951], No. 9473/52. Class 110 (1) In a reversible axial-flow fan in which the impeller blades are similar when viewed from either end of the impeller, the guide vanes on at least one side of the impeller comprise at least a part which is fixed, flat and longitudinal. Preferably, the impeller blades 21 are flat and inclined to the radial plane through the fan shaft. In one arrangement, Figs. 3 and 4, guide vanes 22' are flat and parallel to the fan axis, while guide vanes 26 are formed by resilient plates which are held flat and parallel to the fan axis over part of their length by angle irons 27. The free ends 28 of the vanes 26 are engaged by radial pins 31 carried by a ring 29 which can be turned by a handle 30 to deflect the ends 28 in the direction shown, which is suitable for a flow in the direction f with the impeller rotating in the direction f1. To reverse the flow, handle 30 is operated to reverse the deflection of the ends 28 and the impeller is rotated in the opposite direction. Means may be provided for locking the ring 29 in one or other of its positions In a modification, Fig. 6, each adjustable vane has a rigid part 32 and a flap 33 hinged to it at 34 and movable by means of a fork 36 carried by a control ring 35. In a further modification, both sets of guide vanes are adjustable, either the flexible or hinged construction being used. Alternatively, both sets of guide vanes are flat and parallel to the fan axis over their entire length. The fan may comprise two or more stages.