Patent GB-791556-A (GB)
Title: Gyroscopic apparatus
Inventor: BEACH LENNOX FREDERICK
IPC: G01C19/38
Filed: 1955-06-10
Abstract: 791,556. Gyroscopic apparatus. SPERRY RAND CORPORATION. June 10, 1955, No. No. 16823/55. Addition to 763,750 [Group XXXV]. Class 97(3) [Also in Group XXXV] In a modification of the apparatus of the parent Specification each gyroscope is mounted with freedom of angular movement about its two gimbal axes in a housing, the two housings being detachably mounted as units in vertical alignment on the platform, one above and the other below the gimbal axes. As shown in Fig. 1, a pair of gimbals 6, 8 are supported on a base 2 for rotation about axes 4, 10. A platform 12, rotatable on ball bearings 14 on the inner gimbal ring 8, supports the gyroscopes 11, 13, one above and one below. Platform 12 has gears 24 and 25 mounted thereon; a follow-up motor 22. engages the gear 24 to drive the platform, the second gear 26 below gear 25 driving the. fine and coarse compass transmitters. Follow-up motors are also provided for driving the gimbal rings. The ship's heading is shown on a large annular dial 42 on top of a housing, and fine and coarse readings of the pitch and roll are obtained from fine and coarse transmitters. As shown in Figs. 3 and 4, the gyroscope rotor is mounted in a sphere 72 which is supported on gimbals 74, 76, and floats in a liquid within a housing 64. The sphere 72 is partially filled with helium at low pressure, and contains the gyro rotor 92, 93 which is of squirrel cage construction and is driven by a stator mounted on a fixed shaft 86. Rotor windings and parts are symmetrical and thermal expansions will take place equally in both directions from the centre thereof. Meridian seeking properties are imparted to the gyro compass by a liquid level device 100 secured to the ring 74 to be tilted with the gyro about its .horizontal axis 62. The liquid level is filled, but for an air bubble 68, with a conducting fluid or electrolyte 102 of sufficient viscosity to prevent surging of the liquid in phase with the roll and pitch of the ship. The output of the level is linear within the limits allowed, i.e. degree, so that intercardinal rolling errors are substantially eliminated, and the torquers and liquid level are designed to give the compass a period of about 84 minutes, so that the ballistic deflection is reduced to a negligible amount. The output of the liquid level controls one or more torquers 104 and 104<SP>1</SP> which may be of the E type and are mounted on a portion of the framework 54 on opposite sides of the east-west horizontal axis 62. Also controlled from the output of the liquid level is a damping torquer 106 which is mounted on the horizontal ring 74 to exert a torque about the vertical axis of the compass to reduce the tilt and to damp it. A pick-off 108 mounted on the ring 74 controls the azimuth servomotor. A pick-off 110 secured to the framework 54 and operating in conjunction with an armature 112 secured to the ring 76, actuates the pitch and roll servomotors on relative tilt of the gyroscope about its horizontal axis 62, to maintain the platform level about the east-west axis. The stabilizing gyroscope is not illustrated, but is similar to the compass gyroscope shown in Figs. 3 and 4. It likewise has torquers similar to the azimuth torquers 104, but which are controlled not from a liquid level device, but from a pick-off similar to 108 acting to detect relative displacement in azimuth between the ring 12 and the stabilizing gyroscope, the arrangement being such that the spin axis of the stabilizing gyroscope is maintained east-west; in other words, at right angles to the spin axis of the compass gyroscope. Similarly a levelling torquer like 106 may be provided, actuated from a liquid level like level 100 but sensitive to tilt about the north-south axis. A resolver is provided for resolving the output of the two pickoffs into the roll and pitch components. A caging device is provided to lock each gyroscope when not operating. A plunger 115 is operated from a lever 118 pivoted at 120<SP>1</SP> and is controlled by. a solenoid 122. When the solenoid is energized the plunger is pushed from the left in Fig. 3 to pass through hole 77 in bracket 63 and engage a conical depression in ring 80. The construction is such that either gyroscope may be removed from the instrument without disturbing the other.