GB822564A - A control system for a device to be controlled - Google Patents

Abstract

822,564. Automatic speed-control systems. UNITED AIRCRAFT CORPORATION. June 21, 1956 [June 23, 1955], No. 19244/56. Class 38 (4). In a system wherein speed of a propeller is controlled by varying its pitch at a rate proportional to the error, correction is opposed by a rate-of-pitch-change signal within predetermined error limits. An error signal developed at point 82, Fig. 1, by the unbalance of bridge 70 as a result of the frequency change in generator 68 by a speed deviation of engine 10, is applied to effect pitch correction through a chopper amplifier 86 and a proportional solenoid 60. Pitch change is effected by a cam 16 through piston 14 and hydraulic pump 44 in accordance with the positioning of valve gear 40, 42 by the solenoid 60 through fluid pressure control gear 58, 62, 64, rack 56 and pinion 54, and threaded sleeve 38 in the internally threaded member 32. The opposing rate-of-pitch-change signal which is communicated through shaft 20, differential gear 22, and gear-wheels 30 and 88 imparts a return motion to sleeve 38 to cut off the hydraulic pressure, and moves a potentiometer arm 94 to apply, to the chopper amplifier input, a signal proportional to the rate of correction and limited by the reversed rectifiers 108, 110, whereby hunting is avoided and the sensitivity of the system for large errors increased. The signal is opposed to the error signal.