Patent GB-538346-A (GB)
Title: Means for controlling the direction of the axis of a gyroscope
IPC: G01C19/36
Filed: 1940-01-25
Abstract: 538,346. Gyroscopic apparatus. NISBET, R. H., HARDING, W. G., and SPERRY GYROSCOPE CO., Ltd. Jan. 25, 1940, Nos. 1494 and 17447. [Class 97 (iii)] In a gyroscopic apparatus employed as an indicating instrument or as a control instrument for an automatic pilot, baffle means are provided on the rotor bearing frame to intercept continuous air jets for applying a torque in one direction or the other, and thereby precessing the gyroscope so as to follow a controlling member mounted for rotation through at least 90 degrees relative to the gyroscope about the secondary (vertical) axis of sensitivity. The axis of the gyroscope may, for example, be caused to follow a controlling member positioned by a direction-giving instrument such as the repeater of a magnetic compass, the slower precessional movements of the gyroscope avoiding intrinsic wandering. In the directional gyroscope shown in Fig. 1, the rotor 1 is driven by air jets as described in Specification 394,412 and deviations in direction of the craft to which the gyroscope is applied are detected by observing a compass card 17 attached to the vertical ring 9. If extraneous torques change the direction of the gyroscope, inclined air jets issuing from holes 44, 45 in a U-shaped controlling member 31 act differentially on a partial hemispherical baffle 37 attached to the rotor-bearing frame 4 and cause the gyroscope to precess about the vertical axis A, A<SP>1</SP> until restored to its normal position relative to the controlling member 31. If the craft banks so that the axis A, A<SP>1</SP> becomes inclined, the spherical form of the baffle 37 prevents the air jets from affecting the resultant torque. The controlling member 31 may be turned about the vertical axis A, A<SP>1</SP> by gearing operated by a shaft 34. In Fig. 3 the invention is shown applied to a directional gyroscope of wellknown type and provided with means for controlling the steering of aircraft. The gyroscope is shown in its locked or " caged " position resulting from the inward operation of the push-pull knob 46 as described in Specification 419,816. In the operative position of the gyroscope, the knob is pulled out to free the parts. If the aircraft yaws, air ports 68, 69 adjustably mounted on the casing move relative to the diametrical edge of a semi-circular plate 70 secured to the vertical gyroscope ring 9 and differentially affect the flow of air through the ports to two pipes 56 (one pipe only shown). An external relay device (not shown) connected to the two pipes controls the aircraft's rudder, for example as described in Specification 416,813 and causes the aircraft to turn to restore the original alignment of the ports 68, 69 with the diametrical base of the plate 70. The air-jet nozzles 74, 75 (and two similar nozzles at the opposite side of the vertical ring 9) for applying torque to the gyroscope are carried by two hollow U-shaped structures 70<SP>1</SP> secured to opposite sides of the vertical ring 9. The nozzles direct air on to two turbine wheels 80, 81 attached to the rotor-bearing frame 4. The air jets are partially interrupted by a controlling baffle 82 comprising two semi-circular strips attached to a spindle 83. In the normal position of the baffle the torques are balanced, but when the baffle is rotated, the interception of the air jets is varied and a torque is applied to cause the gyroscope to precess around the vertical axis A, A<SP>1</SP> towards the normal position relative to the baffle. The controlling baffle 82 (or the controlling member 31, Fig. 1) may itself be governed by the movements of a magnetic compass 90 connected to the baffle 82 by a transmitter 91, receiver 92 and gearing 93 ; or alternatively the baffle 82 may be governed through the agency of a servo-motor operated for example as described in Specification 513,624. In a further modification, Fig. 5, an air jet from a nozzle 97 carried by the vertical ring 9 is normally divided into upward and downward streams by the vertical abutting edges of two oppositely-directed conical surfaces or baffles 99, 100 supported by rollers 102, 103 for rotation by the repeater shaft 111. The divided streams impinge equally on a serrated segment 94 carried by the rotorbearing frame 4 and the torques are balanced. If the conical surfaces are displaced so that one or other of them pre-dominates, a corresponding torque is produced by the jets acting on the segment 94, and the gyroscope is caused to precess about the vertical axis until the normal position is again reached. In a modification, Fig. 8 (not shown), the nozzle 97 is replaced by two nozzles. In a further modification, Fig. 9, air jets issuing from nozzles 113, 114 in the vertical ring 9 are normally each bisected by the ends of a semi-circular baffle wall 115, and no resultant torque is then applied to the gyroscope. If the baffle is rotated about its vertical axis, for example by a magnetic compass repeater connected to the shaft 119, one or other of the air nozzles 113, 114 is fully opened and the other is closed by the baffle. The full jet is directed through one or other of two tubes 135, 136 to play upon a turbine 139 fixed to the rotor-bearing frame 4 thus applying a torque to the gyroscope and causing it to precess until the neutral position relative to the baffle is again reached. Specification 549,042 and U.S.A. Specification 2,003,270 also are referred to.