GB190816592A - Improvements relating to Fans, Pumps, Propellers, and the like. - Google Patents

Abstract

16,592. Vojacek, L. Aug. 6. Centrifugal pumps.-Centrifugal impellers for use as pumps &c , are formed with blades the inlet edges of which extend from the hub almost to the periphery, and are set to receive the axially-entering fluid without shock. The blades are of U of half- U section according as the impeller is of the double or single inlet type, and the peripheral edges may overap and be united to form a ring. The blades may be secured to a conical boss, and may be formed with straight backs inclined at any angle to the shaft, or with curved backs concave or convex towards the direction of rotation. Fig. 2 shows a blade of a double-inlet impeller, Figs. 3 and 3<a> being cylindrical sections on the lines b-b and b<a>-b<a> respectively. The inlet edges extending from the hub 2 to the periphery 22 are set at every point so that the fluid enters without shock, the factors considered being the axial entering velocity of the fluid and the linear velocity of the rotating point. It is stated that with this type of impeller the ratio of the axial inlet velocity to the speed of the shaft is constant. The impeller is narrowed towards the periphery to cause the fluid to fill the spaces between successive blades. The impeller may be cast in one piece. Figs. 7 and 8 show a double-inlet impeller the blades of which may be developed into a plane and may be made from sheet metal. The edges 14 of one blade overlap the preceding blade and are secured to it, thus forming two peripheral rings. In single -inlet impellers, one edge of each blade is secured to the disk on the shaft. Fig. 21 shows a modification in which the blades are secured to a conical hub 19, and are surrounded by an outer ring 21 which may or may not be of the same conicity. The edges of the blades touching the hub 19 need not lie in axial planes; in this case, if the edges are straight, the hub will be no longer conical. The parts may be connected by riveting, soldering, or welding, and the impellers may be used with suitable casings and diffusers.