Patent GB-1166692-A (GB)
Title: Gyro Vertical Erection Control System and Method for Gyro Erection Loop Cut Off
IPC: G01C19/46
Filed: 1967-07-18
Abstract: 1,166,692. Gyroscopic apparatus. BENDIX CORP. July 18, 1967 [July 25, 1966], No.32902/67. Heading G1C. In an erection system for an aircraft gyrovertical 22, Fig. 1 comprising pendulums 87, 109 for detecting tilt about the pitch and roll axes of the aircraft, these pendulums controlling the action of restoring torque motors 61, 125, the system is controlled by means which cut the servo loops to the torque motors when the rate of change of airspeed or of aircraft heading exceed predetermined threshold values, the airspeed and heading of the craft being sensed by means giving electrical outputs corresponding to the sensed values, and these outputs being used to interrupt the respective servo loops when the determined threshold values are exceeded. The gyro-vertical 22 comprises a rotor with a vertical spin axis 25 disposed in a pitch gimbal 51 mounted on shafts 53 in a roll gimbal 52, in turn mounted on shafts 54 in a gyro case 50. Deviation of the axis 25 from the vertical about the aircraft pitch axis is sensed by the pendulum 87 the attitude of which controls a pitch synchro 68 connected in a servo loop with the torque motor 61. A pitch sensor synchro 56 is also provided and this is coupled to an indicator 55. Similarly deviation of the axis 25 from the vertical about the aircraft roll axis is controlled by a servo loop comprising pendulum 109, synchro 90 and torque motor 125. A roll sensor synchro 64 is also coupled to the indicator 55. Switches 79, 113 are interposed in the two servo loops and these are actuated to open the circuits by energization of relay windings 89, 120 under control of signals derived from amplifiers 152, 222, Fig.2. An airspeed sensor 187 positions a shaft 185 and thus the rotor 181 of a synchro 179 in accordance with the sensed airspeed. The synchro 179 is coupled to a follow-up synchro 170 and the output signal thus derived on conductor 165 is used to drive a servomotor 202 and this servomotor drives through gearing 214 the rotor of the synchro 170 to a null position and through gearing 216 a rate generator 164, and also through a shaft 212 an airspeed indicator and control 213. The rotor of the rate generator is arranged to be driven at a speed proportional to the rate of change of airspeed of the craft so as to provide at its output winding 162 a voltage having the amplitude but opposite phase to that supplied by the conductor 165 from the synchro 170. This stabilizes the operation of the servomotor 202 in a conventional manner. The voltage from the winding 162 is supplied to the amplifier 152 and when this exceeds the predetermined threshold value the winding 89 is energized to cut the pitch erection servo loop. A similar circuit to that used for the airspeed indication is employed for cutting the roll erection servo loop when the rate of change of heading sensed by an azimuth signal generator exceeds the desired value. If desired the airspeed sensor may be coupled through an amplifier whose output depends on the rate of change of the input signal and the pendulums 87, 109 may be replaced by electrolytic level sensing switches.