Patent GB-367692-A (GB)
Title: Improvements in or relating to gyroscopic compasses
IPC: G01C19/38
Filed: 1931-06-26
Abstract: 367,692. Gyroscopic c compasses. NAAMLOOZE VENNOOTSCHAP TECHNISCHE HANDEL MAATSCHAPPIJ GIRO, 142A, Noordeinde, The Hague. June 26, 1931, No. 18546. Convention date, July 3, 1930. [Class 97 (iii).] Gravity responsive means, arranged to exert no reactive influence on the gyroscope carrier is employed for measuring one or more of the factors (e.g. tilting of the gyro axis and the couple exerted by the damping means) causing the gyro to precess from the meridian and the measurement is used to give a correction to be applied to the gyro indication or is automatically combined with the gyro indication to give a corrected indication. Fig. 2 shows an embodiment in which the gyro carrier 1 floats freely in a surrounding spherical casing 2 carried by the cover-plate 4 of a container 3 filled with liquid. The container 3 is mounted in gimbals and caused by motors to follow the movements of the gyro casing 1 about the three principal axes as described in Specifications 296,790 and 309,860, [both in Class 97 (iii), Thermometers &c.]. The cover-plate 4 carries a pair of liquid containers 5, 12, connected by a tube of large diameter and a pair of containers 10, 11 connected by a tube of small diameter so dimensioned that the equalizing period of the system is the same as that for the damping containers 13, 14 arranged in the gyro carrier 1. Each of the containers 10, 11, 5, 12 is provided with a pair of electrodes 8, 9 ; 15, 16 ; 6, 7 ; 17, 18, respectively, immersed in the liquid and arranged as shown in Fig. 3 in a double Wheatstone bridge of which the remaining arms comprise opposed coils 25, 20 and 24, 21, forming the primary coils of a transformer having a single secondary 22. An alternating current source 19 supplies the Wheatstone bridge. The rate of precision of the gyro from the meridian depends on the tilt of the gyro axis from the horizontal and the disturbance of the normal position of the damping mass. Alteration of the level of liquid in the containers 5, 12 and 10, 11 depends on these two factors respectively and causes an unbalanced current in the Wheatstone bridges which are arranged so that the current produced in the secondary 22 is proportional to the resultant rate of precession of the gyro. The current from the secondary 22 is amplified at 35 and drives a variable-speed motor 26 the latter turning a screw 27 through gearing 36. A worm wheel 28 carrying a pen 29 for registering the ship's course is carried by and in engagement with screw 27 and a further screw 31 driven by a compass repeater 32. When the motor 26 is out of action the motor 32 causes the pen 29 to trace the path with the deviations of the compass and when the motor 32 is out of action the motor 26 causes the pen 29 to trace the deviations. Together the motors 26 and 32 cause the pen 29 to trace the true path of the ship. Instead of using the resistance of the liquid in the containers 10, 11, 5, 12 to effect the control, inductive or capacitative impedances may be used. In a modification a pendulum mounted in a follow-up casing containing conducting liquid is supported on the cover-plate 4. A flattened area at the bottom of the pendulum coacts with a pair of contacts fixed in the casing so that relative motion of the pendulum and casing due to tilting of the gyro axis brings into operation a motor driving the follow-up casing, and a screw on which is a threaded sleeve carrying a friction wheel. The latter is mounted to slide axially on a square sectioned spindle and normally contacts with the centre of a uniformly rotating disc. Tilt of the gyro axis causes the wheel to be displaced from the centre of the disc a distance proportional to the rate of precession of the gyro from the meridian and the spindle to be rotated proportionately to the amount of precessional deviation.