| 摘要 |
<p>991,444. Centrifugal and axial-flow fans. DAVIDSON & CO. Ltd. April 21, 1964 [May 1, 1963], No. 17179/63. Heading F1C. In a centrifugal or axial-flow fan having a number of rotatably adjustable and substantially radial vanes in its inlet for controlling the fan output, some of the vanes have different rates of movement from the remainder whilst all simultaneously assume the fully open and fully closed positions. Guide vanes 16, Figs 2 and 5., are pivoted at their radially inner ends to a central boss and at their outer ends to pivots 17 connected through linkages 23 to 26 to a common ring 19 angularly adjustably mounted on rollers 20. Alternatively, each vane may be provided with an individual shaft. The ring 19 may be adjusted by an hydraulic piston-cylinder assembly 21, a solenoid or other electrical means, or manually. The links 23a (Fig. 5) associated with vanes 16a are of a different length from the links 23 so that the vanes 16a, as compared with vanes 16, initially open more rapidly but are slower in their final movement to their fully open position. Alternatively or additionally the links 25 may be of different lengths. If the majority of the vanes are arranged to close quickly, the links 23 of some or all the vanes may have spring or other resilient means to permit further movement of the ring 19 and the associated links after full closure of the vanes. In an alternative embodiment, Fig. 8 (not shown), the vanes are arranged within the inlet eye 12 with their axes normal to the conical surface thereof. In a further embodiment, Fig. 9, the vanes are arranged in the eye 12 in each of the two suction boxes 29 of a double inlet fan, vane adjustment being achieved by an actuating device (not shown) moving a lever 38 which in turn rotates adjusting rings 19 through a lay-shaft 37 and linkages 33 to 36.</p> |
