GB1201442A - Liquid pumps having axial flow impellers - Google Patents

Abstract

1,201,442. Axial-flow pumps. MIXING EQUIPMENT CO. Inc. Feb.4, 1969 [Feb. 15, 1968], No.5929/69. Heading F1C. An axial-flow liquid pump comprises a housing or way in the form of a generally circular-walled duct which, in the region of the pump impeller, has an inside diameter substantially larger than the impeller diameter, an annular wall joined to the duct wall on the input side of the line of intersection with the duct wall of the plane of the input face of the impeller, another annular wall joined to the duct wall on the output side of the line of inter-section with the duct wall of the plane of the output face of the impeller, each annular wall extending inwardly to an edge having a diameter approximately equal to the impeller diameter and located approximately in the plane of the input or output face, as the case may be, of the impeller at the impeller periphery, the diameter of at least one of the edges being slightly larger than the impeller diameter, the annular walls being continuous around the duct to form a region extending radially around the impeller for a substantial distance beyond the impeller periphery between the annular walls and the duct, and the impeller being supported so as to be capable of movement relative to the axis of the duct between the annular walls as a result of turbulence in the liquid. The duct wall 10, Fig.1, is of substantially larger diameter than the impeller 11, sealing between the tips of the impeller blades 13 and the duct wall being provided by conical walls 15, 19 which extend inwardly to edges 17, 21 of approximately the same diameter as the impeller. Annular plates 18, 22 extending between the edges 17, 21 and the duct 10 may be provided, and the spaces thus enclosed between the duct 10 and the walls 15, 19 may be filled with material. At least the edge 17 is sufficiently larger in diameter than the impeller 11 to enable the impeller to be lowered past it into the position shown. The edges 17, 21 are spaced apart axially of the impeller a sufficient distance to accommodate relative axial displacement of the blades 13 and also to accommodate lateral deflection of the impeller. Instead of being separate parts, the conical walls 15, 19 may be formed by indentations in the wall of the duct 10. The conical walls 15, 19 and the annular plates 18, 22 may be omitted, the duct then being of approximately the same diameter as the impeller upstream and downstream of the impeller but having a portion of larger diameter over the extent of the impeller. Fig. 5 shows a duct having an upper portion 72 substantially larger in diameter than the impeller and a lower portion 76 of approximately the same diameter as the impeller, a conical wall portion 71 and an annular plate 77 corresponding to the wall portion 15 and plate 18 of Fig. 1 being provided above the impeller. The impeller (not shown) is located between the edges 73 and 74.