Patent GB-209052-A (GB)
Title: Improvements in gyroscopic compasses
IPC: G01C19/38
Filed: 1923-11-29
Abstract: 209,052. Thompson, H. H. Dec. 27, 1922, [Convention date]. Gyroscopic compasses.-In a compass in which gravitational control is effected by a liquid level device, such as that described in Specification 131,987, the liquid acts on the gyroscope through floats &c. in a direction to impart gravitational stability thereto. In the form shown in Figs. 1 and 2, the suspension for the compass comprises the usual gimbal rings 1, 2 Within which is pivoted the follow-up element 4 supporting the vertical ring 10 in which the rotor casing 13 is mounted on horizontal pivots 14, 15 in substantially neutral equilibrium. The liquid control means comprise containers 26, 27 for mercury &c., connected by a tube 28 and carried by a frame 25 which is secured to the ring 10. Supported by the liquid in the containers are floats 30, 31 carried by a frame 32 pivoted at 33 to the ring 10 and extending up over the casing 13 to which it is connected by a pin 34 on the casing engaging in a bearing 34<1> on the frame. In order to produce a damping effect the flow of liquid through the tube 28 may be so retarded as to be out of phase with the oscillations of the casing 13. Separate damping-means may be provided, comprising liquid-containers 80, 81 secured to the casing 13 and connected by a fine bore tube 82. In order to increase the directive power when the gyro-axis is near the meridian the areas of the floats may be so proportioned in relation to those of the containers that a considerable variation in the liquid levels results from a small movement of the floats. The period of transfer of the liquid is such that substantially no movement occurs during rolling or pitching of the ship, but that a transfer of liquid takes place in consequence of a change of course or speed. The control means may be stabilized by a vertical gyroscope 84 mounted on horizontal pivots 36 in a frame 37 secured to the follow-up ring 7. To reduce static friction about the verticalaxis without setting up hunting of the follower. the sensitive element itself is continuously oscillated about this axis. A valve controlled by an arm 87 which is automatically oscillated b electromagnets 88, 89 directs an air current from the rotor casing along the pipes 92, 94 alternately, and so produces an alternating torque about the horizontal axis which effects the desired oscillation about the vertical. The contacts on the follow-up element are separated by an insulating portion of sufficient length to prevent the transmission of this oscillation to the follower. In the modification shown in Fig. 4, the frame 25<1>, instead of being secured to the vertical ring, is mounted on the follow-up ring 7 on horizontal pivots 40 coaxial with the pivots 14. 15. The floats are replaced by pistons 30<1>, 31<1> the rods 48 of which are connected by bell-cranks 45 to rods 49 connected to the sleeve 69 surrounding the pin 34 on the rotor casing. This pin may be displaced from the vertical axis of the casing so that a damping effect is produced, as in Specification 131,987. The stabilizing gyroscope 84<1> is pivoted in frames 37<1> secured to the frame 25<1>. In a further modification the frame 25<1> is again pivoted to the ring 7 and floats 30, 31 as in Figs. 1 and 2 are employed, the frame 32 being also pivoted to the ring 7. In both these modifications static friction about the vertical axis is overcome by oscillating the follow-up element in the known manner.