GB798480A - Improvements in or relating to centrifugal compressors - Google Patents

Abstract

798,480. Centrifugal compressors. CHRYSLER CORPORATION. July 4, 1955, No. 19313/55. Class 110 (1). A centrifugal compressor comprises blades extending generally radially from an impeller hub and supported thereby against axial and rotational movement relative to the hub but supported against radial movement only by an annular shroud closely encircling the radially outer ends of the blades. A compressor comprises an impeller hub 61, Fig. 1A, and an inducer hub 17, held together and to the rotor 35 of the driving turbine by means of a tie-rod 44 screwed into the hub 17 at 65. The inducer shroud 58 is supported at 55 by the impeller shroud 48, the connection being by brazing or a force fit. Inducer blades 72, 73 may be attached to the hub 17 by means of integral portions 70 which fit into slots in the hub. Preferably, the slots are formed so that the chordal lines of blades 72 are nearer the axial direction than those of blades 73, and the exit angle of blades 72 may be substantially equal to the entrance angle of the impeller blades 45. The chord length of the inducer blades is substantially proportional to the radial distance from the impeller axis. The inducer blades may be of plastics material and of aerofoil or laminar section. In the embodiment shown in Fig. 2, inducer blades 156, 172, 173 are carried by hubs 155, 161, 165 respectively, the hubs being secured to the shaft 44 by a key 175 and a nut 167. The impeller 112 is fixed to the shaft 44 by pins 152 and a flanged member 153. The blades 156 form continuations of the impeller blades 145 and may be cast integral with the inducer shroud 158 and hub 155 or welded thereto. The blades 172, 173 are supported by pins 174 engaging holes in the shroud 158 and by root portions which engage slots in the hubs 161, 165 and respectively abut against an axial extension 164 of the hub 165 and against the nut 167. In a further embodiment, the inducer blades are formed with roots 271, Fig. 5A, which fit into slots in the respective hubs, axial displacement being prevented by engagement of the roots against the adjacent hubs or hub-securing nut. As before, the blades may be supported at their outer ends by pins engaging the inducer shroud.