Patent GB-383164-A (GB)
Title: Improvements in or relating to gyroscopic compasses
IPC: G01C19/38
Filed: 1932-04-05
Abstract: 383,164. Gyroscopic compasses. GILLMOR, R. E., Red Brook Road, Great Neck, Long Island, New York, U.S.A. April 5, 1932, No. 9750. Convention date, Jan. 2. [Class 97 (iii).] A gyroscopic compass comprises a ball adapted to be spun about a substantially horizontal axis and supported, when spinning, on a film of air for freedom for turning in any direction, a gravitationally responsive device, being connected to the ball for imparting meridian seeking properties. The ball is preferably supported in a cup on a self-generated air film and may be provided with a non-contacting follow-up system. In the form shown the ball 1 rotates in a cup 2, carried by a spider frame 4 in the follow-up structure 5, and is supported initially by compressed air supplied from the pump 32 through the pipes 81, 82 and then on a selfgenerated air film. A shaft 10 projecting through endplates 11 in the ball 1 carries a three-phase A.C. stator 9 for driving the ball, damping bottles 13 connected by a small bore pipe 14, a bail 15 provided with balancing weights 16, and a soft iron armature 17 which co-operates with the transformer 18 controlling through an amplifier the azimuth motor 19 adapted to rotate the follow-up frame 5 about its bearing 6 in the spider 7. The tendency of the reaction of the stator 9 when driving the ball to swing the bail 15 is resisted by an electromagnet 20 fixed to the bail and co-operating with a track 21 fixed to the follow-up element 5. In an alternative a roller bearing fixed to the follow-up element 5 co-operates with a slotted track in the bail or vice versa. In the former case the arrangement provides damping forces when the rotor axis tilts. In a further alternative the bearing may be fixed to the follow-up element in line with the transverse horizontal axis of the ball and the horizontal track fixed to the bail structure or vice versa. In the former construction the arrangement serves to undamp or increase oscillations of the rotor. According to a further alternative the reaction of the stator is balanced by air currents led from the equator of the ball and caused to impinge on a vane fixed to the stator. In order to give the compass a short meridian seeking period when starting, the entire compass structure in the gimbals 31 is locked to the bail 15 by a pin 28 which is automatically controlled by compressed air from the pump 32. The latter is driven by a motor 33 the circuit for which may be closed by a delayed opening switch or by an electromagnetically operated switch normally maintained open by the current supplied to the stator 9. U-shaped cages 85 for supporting the shaft 10 may be brought into operation by the pump 32. The compass is stabilized in its gimbals about a N-S axis by a ball gyroscope 22 rotating in a cup 23 on a film of air provided from an outside source or by the rotation of the ball or both. The ball is driven and automatically centralized by a stator 27 and has at one end a bearing 25 cooperating with a curved slot 26 in the cup. A further gyroscope may be provided to stabilize about an E-W axis. Alternatively the compass may be stabilized about a horizontal axis transverse to the axis of the ball 1 by providing vanes fixed to the gimballed system and adapted to co-operate with the equatorial air stream thrown off from the ball 1. Means for applying a correcting torque to the ball 1 in accordance with the latitude and speed of the ship comprises a pair of oppositely-wound stators adapted to apply electromagnetic torques directly to the ball 1 and differentially masked by an armature placed between the stators and the ball so that the resultant torque depends on the position of the armature. The latter is connected to a shaft 43 which is carried in the slide 44 and bears at its upper end in a circular cam 41 the eccentricity of which may be adjusted by rotation of the knob 38. Fig. 8 shows a modification in which the ball 1 carries an armature winding 58 and is driven by direct current. The spindle 10<1> carries two sets of bottles, one 60, 61, for securing meridian seeking action, and the other 62, 62<1> for damping. Two orifices 59 are provided in the cup 2 and are adapted to supply compressed air on tilting of the ball to one or other of the pipes 65, 66 connected to the bottles 62, 621 so that liquid is blown through the pipe 67 to the bottle on the high side. The apparatus is enclosed in a dustproof housing comprising two tightly fitting covers 50, 51.