Patent GB-504913-A (GB)
Title: Improvements relating to gyroscopic instruments
IPC: G01C19/38
Filed: 1937-07-28
Abstract: 504,913. Gyroscopic compasses. SPERRY GYROSCOPE CO., Inc. July. 28, 1937, Nos. 20944 and 20945. Convention dates, July 28, 1936 and July 31, 1936. [Class 97 (iii)] Gravitational control is effected by means of air jets issuing from a small pendulum carried on the sensitive element. The gyroscopic compass shown has a follow-up casing 5, rotatably mounted by ball' bearings 6 and peripheral rollers, 7 in a housing 4, which is universally suspended by a gimbal 2 in the binnacle 1. 'The vertical frame 10 has a downwardly extending, stem 12 having at the bottom a button 13 co-operating with a cup 14 on the casing 5 to form a lower air bearing and at the top a bowl shaped member 10<1> the lower surface of which co-operates with a cup 9 on the casing 5 to form an upper air bearing. The concave upper surface of the member 10<1> co-operates with the spherical periphery of the rotor casing 16 to form a supplementary air film support for the casing 16. A cup 18 may also be provided at the top. The casing 16 is constrained to movement about a horizontal axis in the frame 10 by spaced air bearings formed by cups 19 on the frame 10 and buttons 19<1> on the rotor casing 16. Air is withdrawn by a pump from the sealed casing 5 through the bearing 6 and enters through the passage 165 to the chamber 66 from which part passes to the air bearings 13, 14, and 9, 10<1> and the remainder to a passage 70 within the stem 12. At the top of the passage 70 part of the air passes to the air bearings 10<1>, 16 and 18, 16 and the remainder to chambers 72, 72<1>, Fig. 5, in the frame 10 and from there' through the sleeve valves 73 to a channel 74 leading to the air bearings 19, 19<1>, and through a passage 77 therein to the driving nozzle 21. The rotor 20 is mounted in the casing 16 on ball bearings. The gravitational control is provided by a pair of oppositely directed air jets 83, 84 carried by a small pendulum and co-operating with baffles 85, 86. The pendulum is mounted in air bearings 85<1>, 85<11> in U-shaped block 101 and is damped by paddles immersed in oil. The block 101 is pivoted to the casing 16 and is normally tilted so that the pendulum pivots in a plane slightly inclined to the vertical thus providing damping as well as gravitational control. To eliminate damping during turning or acceleration of the ship, an electric radiant heater is switched on either automatically or by hand and causes a bimetallic strip to remove the tilt of the block 101. To maintain the period of the compass constant for different latitudes the gravitational factor is varied and the rotor speed kept constant. The gravitational factor is varied by adjusting the suction from the casing 5 until a pressure gauge, comprising an aneroid capsule 90 mounted on the frame 10 and connected by links to a pointer, indicates that the appropriate air pressure is being supplied to the gravitational element 83, 84. To maintain the rotor speed constant, the sleeve valves 72, 72<1> are adjusted by links connected to the capsule 90 so as to maintain the air supply to the driving jet 21 constant notwithstanding the changes of pressure within the casing 5. In a modification the valves 72, 72<1> are eontrolled by a capsule, the interior of which is connected to the air supply to the driving nozzle. latitude damping error is corrected by air jets 118, 118<1>, Fig. 5, at the end of the rotor casing 16 opposite to the gravitational element. The supply of air to the jets 118, 118<1> is modified in accordance with the latitude by an aneroid capsule 110 which rotates, through a rack 111 and pinion, a disc 113 having a series of different sized apertures 114 and brings the appropriate aperture into the supply pipe to the jets. A radiant heater is used to operate a bimetallic strip adapted to close one or other of the jets 118, 118<1>, in accordance with the hemisphere in which the compass is being used. A compass card 23 is mounted on the follow-up casing 5 and a subsidiary compass card 22 on the frame 110. Specification 504,912 is referred to.