Patent GB-825917-A (GB)
Title: Improvements in and relating to gyroscopic apparatus
IPC: F16C35/00
Filed: 1956-04-19
Abstract: 825,917. Gyroscopic apparatus. ABBEY. A. (American Bosch Arma Corporation). April 19, 1956. No. 12018/56. Class 97(3) [Also in Group XXXIV] Gyroscopic apparatus has a ball-shaped rotor casing having an equatorial channel with its opposite edges diverging from the centre outward, a gimbal ring in the channel, first members connected between the gimbal ring and the casing and the second members connected between the gimbal ring and a frame. The application described is a gyro-compass of the kind described in U.S.A. Specification 2,677,194.  Suspension. As shown in Fig. 3, the ball-like gyro casing 11 is floated in a liquid in a tank 10. and is supported by a gimbal ring 14 located in a channel 13 formed in the casing and having outwardly diverging walls. Gimbal 14 is connected by torsion wires 15, 16 (see also Fig. 5) to the casing and by torsion wires 17, 18 to the tank 10. Wires 15, 16 are connected to flat springs 19, 20 bridging the channel 13, and wires 17, 18 are fastened to diaphragms 21, 22 fixed to tank 10 by spiders. Sensitive element. As shown in Fig. 4, the ball-like casing 11 has a central ring 23 in which the channel 13 is formed, and on which the stator laminations 24 of the rotor driving motor are mounted. Shaft 30, which carries the rotor 31 of the motor and the gyro wheels 32, 33, is journalled in bearings 27, 28. Bearing 27 is mounted in one end of ring 23, and bearing 28 is mounted in a thin flexible plate or spider 29 mounted at the other end of ring 23. The bearings are preloaded by stressing spider 29, to take up changes due to wear and temperature changes. The casing is completed by caps 35, 36 soldered to the ring 23. Magnet assemblies 37, 38 for pick-off units 43, 44 are mounted inside caps 35, 36. Electrical connections. As shown in Fig. 5, the gimbal ring 14 is made up of two pieces 14a, 14b joined by screws 45, 46 and carries, insulated from it, terminals 47, 48, 49, 50. The torsion wires 15, 16, 17, 18 are insulated from the gimbal ring 14, the springs 19, 20 and the diaphragms 21, 22 to which they are connected. Terminals 51, 52 are mounted in but insulated from diaphragms 21, 22. Connections between the gyro casing 11 and the tank 10 are made by the torsion wires 15, 16, 17, 18 and very flexible wires 53, 54, 55, 56 surrounding them. Mounting of tank. The tank 10, Fig. 3, consists of an upper section 80 fitting into a lower section 81, the joint being made liquid tight by sealing ring 85. The upper cap 82 has bellows 96 to allow for the expansion and contraction of the liquid in tank 10 with temperature changes. A drain plug 98 is provided on the lower cap 83. The tank is suspended in a gimbal ring 86 by shafts 87 trunnioned in bearings 88 formed in a cover 84, which is attached to a flattened portion of the lower section 81 and provided with a sealing ring 85, and encloses a damper 84<SP>1</SP> of the kind described in Specification 825,920. As described in Specification 825,918, the gimbal ring 86 is in turn suspended in a frame 100, Fig. 1, about an axis which is aligned with the E-W marks on the compass card 103. mounted on the frame. This orientation of the gimbal axis reduces the rolling errors. The frame 100 is mounted on a base 104 for rotation by an azimuth motor 105 through gearing 106, 107. Gimbal ring 86 carries a sector gear 108 meshing with a gear 109 driven by a motor 111 mounted on a frame 100. The pivot shaft 112 of frame 100 carries slip rings 113 and is geared to the rotor of a synchrotransmitter 115. A pendulum 120, Fig. 6, is suspended at one side of tank 10. A counterbalance, preferably in the form of a terminal block, is mounted on the opposite side of the tank. Operation. Referring to Fig. 6, if the gyro spin axis is displaced from the meridian, its easterly end will apparently rise as the earth rotates, causing gimbal ring 14 to be displaced with respect to the sensitive element 11. This results in a signal generated in the pick-offs 43, 44 which is applied to motor 111, which drives gimbal ring 86, tank 10 and gimbal ring 14 until ring 14 is again co-axial with the sensitive element. As the tank has been tilted, the pendulum armature 120 is displaced relatively to its pick-off 122, and a signal is generated which is applied to motor 111 to drive the gimbal ring away from the sensitive element, twisting the wires 15, 16 which apply torque to the sensitive element to cause it to precess towards the meridian. By choice of the output polarities of pick-offs 43, 122, the compass may be made either pendulous or anti-pendulous, the direction of rotation of the gyro being chosen accordingly. As the sensitive element precesses towards the meridian, follow-up action between pick-off 44 and motor 105 tends to keep the axis of shaft 87 aligned with the gyro spin axis. A portion of the output signal from pick-off 122 is also applied to motor 105 to produce a slight displacement between tank 10 and sensitive element 11, whereby wires 17, 18 are twisted to apply torque to the sensitive element to precess the gyro axis towards the horizontal, thus applying vertical damping to the gyroscope. Correction of speed and course error and latitude error. These errors are corrected as described in Specification 825,919.