Patent GB-466864-A (GB)
Title: Improvements in or relating to gyro-magnetic compasses
IPC: G01C19/36
Filed: 1935-12-04
Abstract: 466,864. Bearings. SPERRY GYROSCOPE CO., Inc. Dec. 4, 1935, No. 33611. Convention date, Jan. 5. [Class 12 (i)] [Also in Group XX] In a gyro-magnetic compass air bearings provide freedom for the gyro about horizontal and vertical axes and the magnetic element is mounted on the gyro by upper and lower bearings through which air is led to laterally directed air jets carried on the element and adapted to exert torques to cause the gyro to follow the magnetic element. Preferably a single source of air flow provides air flotation bearings for the magnetic element, for a pendulous element for controlling means to correct tilt of the gyro, for the gimbals, and for the rotor, and air jets for driving the rotor and applying controlling torques to the gyro. As shown in Fig. 1, the vertical ring 13 carries upper and lower convex buttons 11, 12, nesting with slight clearance in concave caps 7, 8, fixed in the sealed casing 1. Air is withdrawn from the casing 1 and replaced by air drawn in through screened openings 3, 4, and passages 9, 10 in the caps 7, 8. Part of the air drawn in flows between the surfaces of the buttons and caps and causes the ring 13 to float on a film of air and the remainder passes through central passages in the buttons 11, 12 to a channel 15 in the ring 13. Part of the air in the channel 15 provides similar flotation bearings 19, 20 for the rotor casing G and the remainder passes through passages 22 to nozzles 23, 24 for driving the rotor 25 and to a channel 28<1> in the rotor casing G. The channel 281 supplies air to flotation bearings 52 for the rotor 25 and to flotation bearings 30, 31 for a ring 32 carrying magnets 36. Part of the air supplied to the bearing 30 passes through a channel 38 in the ring 32 to opposite jets 39, 391, Fig. 4, which co-operate with a semicircular baffle 44 fixed to the rotor casing G to provide torques precessing the gyro into alignment with the magnetically directed ring 32. Alternatively the two jets 39, 391 may be replaced by a single jet and the semicircular baffle 44 by a V- shaped baffle. To maintain the spin axis of the gyro in the horizontal plane, the rotor casing G has laterally directed opposing parts differentially controlled by small pendulous blades. In a modification, the ring 32 is replaced by a short piece of thick tubing with hemispherical ends supported by air films between concave caps on the top of the casing G and on a stem upstanding from the casing G and passing through the tubing. In a further modification, the magnetic element comprises a bar magnet 371, Fig. 10, carried in a small block 60 which is supported on air flotation bearings at one end of the gyro casing G<1>. Air is supplied to the bearings from the inside of casing G<1> through a passage 64 with an adjusting screw 72 and a part passes through a passage 66 in the block 60 to upwardly and downwardly directed nozzles 68, 69 which co-operate with knife edges 70, 71 to provide a torque causing the gyro to follow the magnetic element. A similar arrangement to that shown in Fig. 10 is provided at the other end of the gyro casing, but with the block 60 replaced by a pendulous block and with air jets and co-operating knife edges modified to provide a torque for maintaining the spin axis horizontal. The rotor 251 is driven by reaction jets fed through passages 58, 57. A locking and resetting device for the gyro may be provided. All parts except the magnets themselves are made of the same non- magnetic metal, e.g. an aluminium alloy, so that uniform operation under varying temperature conditions is attained.