GB983480A - Improvements relating to impeller vanes for axial-flow blowers - Google Patents

Abstract

983,480. Axial-flow blowers. SCHMIDT' SCHE HEISSDAMPF-G.m.b.H. Jan. 13, 1964 [March 29, 1963], No. 1491/64. Heading F1C. A hollow impeller vane of ribbed frame construction with an external skin, suitable for an axial-flow blower having fixed or adjustable vanes for blowing gas or air at elevated temperatures as in sintering plant or the like, comprises a solid base 1 A provided with a spigot 2 for detachably securing the vane to a hub or shaft. A central tubular spar 5 is located in the base 1A in a close fitting passage 4 in a central step 16, and is welded at its lower end to the spigot 2. Two or more auxiliary spars 7, which may be tubular, are secured by transverse pins 8 or the like in blind bores 6A in lower intermediate steps 19, 20. This stepped arrangement causes any vibrations to be transmitted, through the spars 5, 7, to more than one transverse plane of the base. The solid base 1A causes the centre of gravity of the vane to be in the region of relatively low rotational speed. A tube 11 forms the vane leading edge and a strip 12 is near the vane trailing edge. Parallel ribs 14 of aerofoil shape co-operate with the base and spars to form the framework which is covered by a skin 15. The vane parts may be secured together by welding, riveting or screwed connections. The ribs 14 may be similarly directed, or successively angularly displaced, around the central spar 5. In an alternative embodiment, Fig. 1 (not shown), the top of the base is flat and the blind bores are counterbored to provide a lower transverse supporting plane for the auxiliary spars than for the central spar. It is stated to be known to produce welded sheet metal vanes having a wall thickness which decreases radially outwardly, or produce vanes by combining at least two elements of different thickness by welds extending transversely of the vane axis.