Patent GB-675860-A (GB)
Title: Gyro precessing system
IPC: G01C19/38
Filed: 1949-05-23
Abstract: 675,860. Gyroscopic apparatus. BENDIX AVIATION CORPORATION. May 23, 1949, No. 13736/49. Class 97 (iii). [Also in Group XXXV] A gyro precessing system comprises means on the gyroscope to develop an intermittent signal voltage upon departure of its spin axis from a reference axis, a balanced circuit comprising inductive means adapted to be unbalanced by those voltages and means operative upon the unbalance of the circuit to precess the gyroscope. Preferably means are provided for varying the rate of development of the intermittent signal voltages. As shown, deviation of the axis of the gyroscope from the vertical is detected by a signal source 11 comprising a steel ball 18 free to roll between opposed polepieces 15, 16 in a non-magnetic cup 19, the core 14 for the polepieces 15, 16 being provided with an energizing winding 20 and the movement of the ball being detected by the changing voltages in the windings 17 on the pole-pieces. The coil 20 is intermittently energized by means of a relaxation oscillator circuit 25 so that its magnetic field may decay and allow the ball 18 to roll in response to tilt of the gyro. The anodes and grids of the valves 26, 27 in the oscillator are interconnected by condensers 41, 48 and a relay 44 whose contacts 61 control the energization of the winding 20 is connected in the anode circuit of the valve 27 so as to be energized in each cycle of oscillations. The periodicity of these oscillations may be varied by altering the inductance of the gridleak circuits of the valves 26, 27 and a relay system 72, 73, 74 permits this variation by cutting out one or more of the grid resistors 50-52. On starting up the gyro the switch 87 is closed, thus energizing relay 74 which has a time-delay of five minutes and, through contact 85, relay 73. Relay 73 operates to cut-out resistors 51, 52 from the grid leak circuit of the valve 26 so as to vary the frequency of the oscillator circuit to give an erection rate of 22.5 degrees per minute. After five minutes, when the gyro is running at full speed, relay 74 operates to de-energize relay 73 and to energize relay 72. The grid leak of valve 26 now comprises resistors 50 and 51 and a smaller erection rate of eight degrees per minute results. Switch 81 is adapted to be opened by the gyro when the bank altitude exceeds 3 degrees and by de-energizing relay 72 adds resistor 52 to the grid leak circuit to provide a minimum erecting rate for banked turns of about 2.5 degrees per minute. The voltage variations induced by the rolling ball 18 in the windings on the pole-pieces 15, 16 are amplified by the sections 104, 101, of a duotriode 102 and are then applied to phase discriminator circuits comprising duotriodes 161, 112 respectively. The resultant voltages are applied through magnetic reactors 167, 113 to operate the appropriate erecting torque-motors 13, 12 respectively. In the phase discriminating valve one or other section of the duotriode operates depending upon the polarity of the amplified displacement signal. The anodes 130, 133 are connected to saturating windings 149, 150 of the magnetic reactor 113 which is also provided with primary windings 140, 141 and secondary windings 144, 145, the output of the latter being used to operate the torque motor 12. When either anode circuit 130, 133 operates in response to a deviation signal the associated winding 149, 150 saturates its core, thus destroying the inductive balance and causing current to flow in its associated secondary 144, 145 to energize the torque motor 12 in the required direction.