Patent GB-731737-A (GB)
Title: Improvements in or relating to gyroscopic apparatus
Inventor: PRINCE ALFRED CHARLES AUGUSTUS
IPC: G01C19/38
Filed: 1953-02-13
Abstract: 731,737. Gyroscopic apparatus. SPERRY GYROSCOPE CO., Ltd. Feb. 15, 1954 [Feb. 13, 1953], No. 4090/53. Class 97 (3). A gyroscopic intrument, e.g. for aircraft, comprises a sensitive element which is mounted with limited freedom of angular movement about an axis relative to a supporting frame and a warning indicator rendered operative on angular movement of the sensitive element and its supporting frame through said predetermined amount, whereby an indication or warning may be provided that such relative angular movement has occurred and that, therefore, the indication and/or control effect provided by the instrument may be inaccurate. As shown in Fig. 1, the rotor case 1 of a gyrovertical mounted for spinning about a normally vertical axis CD is pivoted about an axis XY in a gimbal frame 2 which is pivotally mounted about an axis AB in an outer housing 4 in bearings 5 and 6. Bearing 5 is supported in a window 8 through which the indication of the instrument may be viewed. These indications are provided by two horizontal bars 45, 46 pivoted to the gimbal ring by pivots such as 47 and moving up and down in front of a mask (not shown) attached to the gimbal frame 2 by the pin and slot arrangement 18, 48. The gyroscope is erected in known manner by means of torque motors 11, 12 (see also Fig. 2), controlled by liquid level switches 9 and 10 having rolling globules of mercury. Movement of the globule 9a of switch 9 energizes winding 13 or 14 of the torque motor 11 so as to precess the gyroscope back to the vertical. The switch 10 similarly operates the torque motor 12. The gimbal frame 2 may rotate freely about the axis AB but the rotor bearing frame 1 is confined in its movement about the axis XY by means of stops which limit its freedom of movement through an angle between 75 and 89 degrees, preferably about 80 degrees, on either side of its normal operating position. The stops include contacts 15a, 15b and 21a, 21b which are closed when a pin 18 mounted on the rotor bearing frame 1 engages the stop. The contacts energize the windings 22, 23 of an electromagnetic device 24, 25 having a spring centralized armature 28. When the instrument is not in use neither of the windings is energized and the armature 28 takes up a central position in which case label " OFF " on an indicator 30 is visible in a mask not shown. When the instrument is switched on, the winding 23 is energized and the armature is drawn over towards the winding 23 to move the indicator to the " ON position. When either of the contacts 15a, 15b or 21a, 21b are closed the winding 22 of the torque applying means is energized and the indicator is drawn over to the " toppled position indicated by " T " on the indicator 30. This indicates to the pilot of the aircraft that the instrument does not now give a reliable reading. A holding relay switch 36 is closed whenever the contacts 15a, 15b or 21a, 21b are closed and serves to keep the winding 22 energized until a further operation is performed. When the pilot notes that the indicator indicates the "toppled" condition he may depress a knob 37 in the front of instrument which opens a switch 38 in the circuit of a relay R which then operates contacts R33 and R40 which increase the voltage applied to the torque motors so as to bring about quick erection of t.hol,instrument. At the same time the voltage across the winding 23 is increased and winding 22 is de-energized. The holding relay 36 is also deenergized and the indicator 27 will move to the "ON" position. More rigid stops may be provided on the gimbal frame in addition to the contacts 15a, 15b, 21a, 21b. If the instrument is used to exercise automatic control of the aircraft, the contacts 15a, 15b, 21a, 21b may be connected in the circuit which serves when the contacts are closed to disconnect the instrument from, exercising its automatic control. If desired, the quick erection switch 38 may be automatically operated by a time-delay device.