GB1451067A - Gas turbine engines and bladed rotors therefor - Google Patents

Abstract

1451067 Gas turbine ducted fan engines - variable pitch fan blades DOWTY ROTOL Ltd 14 Feb 1974 [17 Feb 1973 (3)] 7883/73 7885/73 and 7886/73 Headings F1C and F1G The invention relates to a gas turbine engine of the by-pass type having a rotor carrying adjustable - blades, the rotor being of self-contained form and rotatable in the by-pass duct of the engine. The rotor shown is a ducted fan rotor comprising a hub 16 mounted on a shaft 5 and carrying angularly adjustable blades 12; the rotor comprises also a fluid-operated actuator 25 of the vane type which is connected to the roots of the blades to vary the angular pitch thereof. Gear-type pumps 47, 47a, 47b are also carried by the hub structure to supply fluid under pressure to the actuator, the pumps being driven upon rotation of the hub, the pump 47b being alternatively drivable by a separate motor M. The hub is formed with sockets 15 in each of which is rotatably mounted in bearings 13, 14 the root portion of a blade 12. Each root portion carries a bevel gear 19 which is engaged by two bevel gear rings 31, 34. The bevel gear ring 31 is formed on a ring member 30 secured to the angularly movable casing part 27 of the actuator 25; similarly the bevel gear ring 34 is formed on a ring member 33 which is secured to the angularlymovable casing parts 28, 32, of the actuator 25. The casing parts 27, 28 carry vanes and move in opposite angular directions when fluid under pressure is supplied thereto, whereby the pitch of the fan blades 12 is adjusted. The pump 47 is secured to a plate member 45 which co-operates with the casing part 44 to define a space 46 in which gear members 50, 52, 54 are mounted, the gear 50 being connected to the gear pump and the gear 54 engaging a gear pinion 56 formed on a tubular member 57 which is fixedly secured at its opposite end 58 to stator structure. Thus as the shaft 5 and hub 16 are rotated the gear pump 47 is driven. The forward portion 36 of the hub 16 is secured on the shaft 5 by means of a spline coupling and by frusto-conical mountings 21, 22. The pump 47a is driven similarly to the pump 47. The pump 47 is a low flow pump and the pump 47a a high flow pump so that pump 47 supplies fluid to the actuator 25 for pitch-change at slow rates and pump 47a supplies fluid for pitch-change at fast rates. The pumps 47, 47a which operate continuously when the rotor rotates discharge through relief valves such as 100, the fluid passing through a spiral passage 106 back to the reservoir 101 from which it is drawn back into the pump; the fluid is cooled by air-flow as it flows through the spiral passage 106, the air-flowing through the adjacent passage 109, the air-flow being assisted by vanes 112. The third pump 47b which supplies fluid to the actuator 25 when feathering of the blades is desired is also driven continuously - it is also drivable when required by a motor M through a shaft 81 having a brake B, the shaft carrying a gear 80 which engages a gear 78 which in turn engages a gear on a tubular shaft 74 which comprises at its forward end a gear pinion 73 which engages a train of gearing whereby the gear pump 47b may be driven. The pilot's control is through a shaft 88 which is connected through a tubular shaft 92, a flange 93 at the forward end of which is connected to a member 94 whereby the axial position of a spool member 83 is controlled. The spool co-operates with a continuously-rotated sleeve 84 and a fixed sleeve 86 of a device 82 to control flow of fluid from pump 47 or pump 47a to the actuator 25 whereby the fan blades are movable slowly or rapidly to the desired pitch setting. In the event of engine shut-down the motor M is operated whereby the pump 47b is driven which supplies fluid to the actuator 25 to move the blades to the feathered position. When the brake B is applied, the shaft 81 is held stationary and thus also the tubular shaft 74 and gear pinion 73 whereby the feathering pump 47b is driven during rotation of the bladed rotor; the brake B is released when the feathering pump is driven by the motor M.