| 摘要 |
1512698 Axial-flow fans GEA LUFTKUHLERGESELLSCHAFT HAPPEL GmbH & CO KG 11 July 1975 [13 July 1974] 29339/75 Heading F1C An axial-flow fan impeller comprises a circular hub plate 16 which on one of its substantially flat surfaces carries housings 21 for the bearings of the pivot spindles of variable-pitch blades 10, a control plate 35 on the end of an axially movable control rod 41 being connected to crank arms 33 by adjustable linkages 34. Each linkage 34 comprises a lever 37 pivoted at one end to a fulcrum bracket 38 carried by a support ring 25 and connected at its other end via a pivotal link 39 and an adjustable screw connection to the control plate 35, a pivotal link 36 being connected between the middle of the lever 37 and the corresponding crank arm 33. The housings 21 carry welded-on mounts 22, 24 bolted to the hub plate 16 and the ring 25 respectively. A sheet metal plate 31 carrying adjustable balance weights 32 may be clamped between a flange 29 on each blade pivot spindle and a flange 30 on the corresponding blade root. Rotation of the control plate 35 is prevented by guide rods 43 carried by the hub plate 16 via a support 42 and passing through bearing bushes adjustably mounted at holes 45 in the control plate. The control rod 41 passes through the hollow drive-shaft 12 of the impeller and is axially movable by means of a servopiston 54, compressed air or hydraulic fluid being supplied to opposite sides of the piston via a pipe 53 and the bore 52 of the control rod, the air or fluid being supplied from non-rotating ducting via a rotary coupling 55. Feedback to the servocontrol valve 57 is provided by a lever 58. Shutoff valves 60 in flexible supply hoses 56 prevent alteration of blade pitch in the absence of a control signal. In a modification, Fig. 6 (not shown), the servopiston 54 is located at the other end of the control rod 41, the servo cylinder 51 then replacing the support 42. In another arrangement, Fig. 5 (not shown), the servo cylinder 51 is stationary and the servopiston 54 is carried by a non-rotating portion of the control rod 41 which is connected to the rotating main portion of the control rod by a coupling which transmits only axial movement. |
