GB973122A - Single degree of freedom gyroscope - Google Patents

Abstract

973,122. Gyroscopic apparatus, UNITED AIRCRAFT CORPORATION. Jan. 25, 1961, No. 2878/61. Headings G1C and G1N. In a single degree of freedom gyroscope the field structure of the electric spin motor is mounted on the fixed casing 99 instead of on the gimbal 98 so that the armature, which is on the rotor, may rotate relative to the field structure about two orthogonal axes viz. the spin axis and the output axis. The housing 99 is of permanent magnetic material having a laminated pole shoe 49 symmetrical about the north pole line N and two laminated pole shoes 50, 51 symmetrical about the south pole line S to form the field structure. Pole faces 94-97 on the inner surface of the floated gimbal 98 are symmetrical with respect to pole shoes 49-51 in the null position. The rotor has spaced armatures 62, 63, each provided with twelve teeth and twelve semi-closed slots and held by snap rings 76-79 on a spider 81 formed with a hub and six pairs of legs. The armatures 62, 63 are wound with input and output windings connected respectively to commutator bars such as 40-46 co-operating with brushes 54, 55 and commutator bars 13-24 co-operating with brushes 52, 53. As applied to a rate gyro, D.C. is applied from source 100 through terminals 74, 75 leads 70, 71, terminals 66, 67, to brushes 54, 55 so that the rotor picks up speed, a centrifugal switch thereon maintaining the speed constant. When a turn occurs about the input axis, gimbal 98 precesses about the output axis against the torsion of a bar 89, a corresponding D.C. output signal being passed from brushes 52, 53 through terminals 64, 65 and leads 68, 69, to terminals 72, 73. Damping is effected by a coil 106, the viscosity of the fluid which floats gimbal 98, and by eddy currents produced by having the gimbal 98 of non-magnetic material having a low resistivity. Since the viscosity of the fluid decreases with increase of temperature, damping decreases also and to compensate for this the non-magnetic material of gimbal 98 may have a slightly negative temperature coefficient of resistance and the ends of coil 106 may be shorted through a resistor 111 having a negative temperature coefficient. As applied to a displacement gyro the torsion bar 89 is removed, or rendered inoperative, and the ends of coil 106 are connected respectively to terminal 107, and either directly or through resistor 111 to terminal 108 so that the coil 106 is used as a torque. In modifications the input commutator is replaced by slip rings and the input comprises three-phase A.C. the output then being D.C. from the output commutator, or single or three-phase A.C. from slip rings or combinations thereof as required. Armatures 62, 63 may be formed as a single armature.