GB560522A - Improvements in or relating to propeller control means - Google Patents

Abstract

560,522. Electric signalling systems. UNITED AIRCRAFT CORPORATION. Feb. 12, 1943, No. 2364. Convention date, Dec. 9, 1941. [Class 40 (i)] [Also in Groups XXVIII, XXIX and XXXIII] A servomotor control system for a variable pitch propeller controlled alternatively by a speed governor or by manually-controlled electrical means, comprises two independent hydraulic systems, one carried by the propeller, the other associated with the speed governor. Each propeller blade is secured to the outer casing of a double-acting oscillating vane motor. The casing has two radial vanes 20, 22, and is rotatable' about a fixed member 24 provided with two radial vanes 26. A pump comprising plungers 31 rotatable about a fixed cam 33 supplies fluid through a conduit 32 to a distributing valve 34. This valve comprises a pair of lands 150, 152 slidable in a ported followup sleeve 142 operated by a cam 146 on the casing 16 acting through a spring-loaded bellcrank lever 144 and controls the supply and exhaust of pressure fluid to and from the oscillating vane motors. The valve 150, 152 is actuated by a single-acting piston 112 loaded by a spring 122 and connected to the valve by rigid members 90, 94 and a slip-joint 92. The left-hand end of the cylinder 86 housing the piston 112 is connected through a pipe 116, solenoid actuated valve 84, pipe 114 and solenoid-actuated valve 82 with a pipe 80, the pressure in which is controlled by the speed governor actuated control valve. This valve comprises a ported sleeve working in another ported sleeve to connect the pipe 80 either with the delivery 76 from a gear-pump 64 driven by bevel gears 44, 46 from the propeller shaft 14 or to the sump 66. To provide an isodromic follow-up, a piston valve 104 adapted to co-operate with ports in the sleeve valve 50 is connected by a lever 98 mounted on a fixed pivot with a piston 100 fitted with a centralizing loading spring 158. The piston 100 works in a cylinder 128 having a throttled bleed port 154 leading to the sump 66 and connected by a pipe 126 with a cylinder 106 housing a piston coupled in tandem with the piston 112. To limit the range of normal pitch adjustment, the spindle 88 of the piston 112 is provided with a pair of stops 168, 170 arranged to cooperate with a stop 172 adapted to be moved out of position when it is desired to feather the propeller or move it into reversed pitch by a solenoid 171. The position of piston 112 and therefor the pitch of the propeller is indicated on a dial 206 by pointers 200, 202 rotated by a " autosyn " receiver 196 energized by mains 272 and controlled by a transmitter 186 geared to the spindle 88. When a selection handle is moved to the manual control position, the valve 82 is actuated to shut-off the governor control and put the piston 112 under the control of a solenoid-actuated valve 184 and the valve 84. These valves are controlled by contact arms 254, 252 on the shaft 198 co-operating respectively with a narrow contact 248 and a semicircular contact 240. The contacts 240, 248 are adjusted to the desired pitch angle by gears 268, 270 rotated by a knob 262 and indicated by a pointer 204. When the selector handle is placed in the " feathered " or reversed pitch position, the contact arms 252, 254 are cut out and the valve 184 placed in the appropriate position. To test the feathering action when the propeller is not rotating, the pump actuating cam 33 is actuated by an electric motor acting through non-reversible gearing and a bell-crank while a cam operates a supplementary pump in parallel with the pump 64.