GB826519A - Improvements in or relating to axial flow fans - Google Patents

Abstract

826,519. Axial-flow fans. AIR CONTROL INSTALLATIONS Ltd., and REEVES, H. C. May 10, 1957, No. 15000/57. Addition to 816,921. Class 110 (1). In an axial-flow fan according to the parent Specification, the pivotal connection between a blade and the hub or between the inner and outer parts of a blade comprises a universal joint permitting movement of the blade or the outer part about axes transverse to a radius of the fan, and each blade is so secured to a part of its joint as to be adjustable about a longitudinal axis of the blade, and means are provided for clamping the blade to the part of the joint in an adjusted position. In the fan shown in Fig. 1, each blade 37 is carried by a shoe 36 having a threaded stem 35 to which a ball 25 is clamped by a nut 39. Each ball 25 is located in a spherical socket formed in the two parts 10, 11 of the impeller hub so that the blade 37 can tilt about any axis at right-angles to a radius of the fan, rotation about the radial axis being prevented by pegs 27, 28 which engage a circumferential groove 26 in the ball. The amount of tilt is limited by a cylindrical socket 40 which surrounds the end of the stem 35. In a modification, Fig. 3, the ball 25 is replaced by a block 46 pivoted on trunnions 44 in a gimbal ring 43 which in turn is pivoted on trunnions 48. Fig. 4 shows a construction in which the universal movement is provided by a rubber ring 56 bonded to the conical faces of a blade-carrying member 54 and a socket 50. The holes in the rim of the hub which receive the attachment bolts for the socket 50 may be slotted to permit the socket to be rotatably adjusted about a radius. In a modification, the rubber mounting is disposed at the radially inner end of the blade stem, and the socket 40 is omitted, limitation of movement being provided in this case by the clearance between the blade stem and a hole in the hub rim through which the stem projects.