Patent GB-722492-A (GB)
Title: Improvements in or relating to gyroscopic apparatus
IPC: G01C19/22
Filed: 1952-11-19
Abstract: 722,492. Gyroscopic apparatus. SPERRY CORPORATION. Nov. 19, 1952 [Nov. 21, 1951], No. 29224/62. Class 97 (3). [Also in Groups XXXV and XXXVIII] In gyroscopic apparatus of the kind that comprises a rotor mounted in a support for spinning about a first spin axis and adapted to be driven from a driving shaft mounted in said support for spinning about a second spin axis, the first spin axis normally coinciding with the second spin axis but being arranged for limited angular movement about a point on the second spin axis, the driving shaft is formed as a part of, or rigid with, a hollow container within which the rotor is mounted, and in which the rotor is driven at the same speed as the driving shaft. In the apparatus shown, a casing 8 driven by an electric motor 10 is journalled at 4, 6 in an outer case 2 and the hub 24 thereof is connected by a tension strut 16 and a flexible diaphragm 26 to a rotor 14 of iron. Thus, the rotor is spun at the same speed as casing 8, but has a limited degree of freedom relative thereto about any axis normal to the spin axis. Fixed to the casing 8 is a soft iron core 30 carrying a pick-up coil 32, and symmetrically arranged in the casing are oppositely-disposed pairs of magnets 36, 36<SP>1</SP> and 38, 38<SP>1</SP>. When the outer case 2 turns, the casing 8 tilts relatively to the rotor 12 and the reluctance of the magnetic circuit is thereby changed and an alternating current signal is generated in coil 32 of amplitude proportional to the relative tilt and a phase sense which depends upon the sense of the turn. A viscous liquid (e.g. silicone) fills the casing 8 and provides a damping torque to ensure that the relative tilt is proportional to the rate of turn of outer case 2. Attached to the ease 2 is the stator of a two-phase generator 33 whose rotor is carried by the casing 8, one phase of this generator may represent elevation and the other azimuth or roll. This generator produces two reference alternating voltages whose phases may be compared with those of the output voltages from winding 32 and two component signal voltages derived which are measures of the magnitude and sense of the component tilts and those of the rates of turn of the gyroscope rotor about two mutually perpendicular axes. The instrument may be mounted on a gun so that these two axes are made to coincide with the elevation and azimuth axes of the gun, as in Fig. 2. In this Figure, D.C. voltages EL and EA respectively proportional to the desired elevation and azimuth rates of the gun are modulated at 60 and 64 by the voltages from generator 33. The outputs of the modulators are combined at 62, the combined output being fed to a differential circuit 63 together with the output from the winding 32. The differential output of circuit 63 is then applied to each of two phase-sensitive rectifiers 66, 68 to one of which is applied one reference voltage from the generator 33 and to the other of which is applied the other reference voltage from the generator 33, with the result that error signals are derived which may be used to modify the inputs of the elevator and azimuth servomotors of the gun in order to turn it about the elevator and azimuth axes at the correct rates. In another form, Fig. 3 (not shown), the magnets 36, 36<SP>1</SP> and 38, 38<SP>1</SP> are replaced by solenoids and one central magnet is provided in place of the core 30 and winding 32; generator 33 also has only one phase. This generator may be replaced by a commutator, Fig. 5 (not shown). Specifications 684,667 and 694,850, [Group XXXVIII], are referred to.