Patent GB-938705-A (GB)
Title: Apparatus for measuring precession deflections in gyroscopes
IPC: G01C19/28
Filed: 1962-02-08
Abstract: 938,705. Measuring electrically. L. BOLKOW, [trading as BOLKOW ENTWICKLUNGEN KOMM.-GES.]. Feb. 8, 1962 [Feb. 9, 1961], No. 4870/62. Class 40 (1). [Also in Group XX] A gyroscope is provided with means for measuring precession deflections, comprising at least one Hall generator and means for producing a magnetic flux therethrough, the latter means being movable by precessional movements of the gyroscope to vary the flux through the generator as a function thereof. Shaft 7 of the outer frame 6 of gimbal mounted gyro 1 is provided with non-magnetic arms 13, 14 carrying radially magnetized arcuate magnets 11, 12 moving in a U-shaped groove in fixed magnetic yoke ring 15. Hall plates 16, 17 are mounted in the groove and rotation of outer frame 6 varies the magnetic flux through each plate to vary its output. In a modification (Fig. 2, not shown), a strip magnet is mounted on the shaft and is provided with arcuate polepieces in the same plane as the magnet, which co-operate'with an arcuate Hall on an ungrooved yoke ring. In a further modification (Fig. 3, not shown) the yoke ring is provided on its inner periphery with two pairs of pole-pieces co-operating with a moving magnet, and Hall plates are provided between one or both pairs of poles and the yoke ring. An arrangement is also referred to in which one or other pole-piece of a magnet lies over a Hall plate. An embodiment in which movements about two mutually perpendicular axes are sensed is described (Fig. 5). Shaft 64 of the gyro wheel 55 is extended at both ends and is provided with part-spherical end-pieces 65, 66. The gyro is mounted on a magnet 59, yokes 60, 61 of which have partspherical polepieces 62, 63. Pairs of Hall plates 67, 68 and 69, 70 are arranged on the respective polepieces, the Hall axes of the respective pairs being mutually perpendicular so that the sense respectively movements in horizontal and vertical planes. In Fig. 6 magnetic disc 71 is eccentrically mounted on one of the gyro shafts 73 and moves inside a ring 76 concentric with the shaft. Magnet 78 drives a constant flux through yoke 80, ring 76, disc 71 and yoke 79. A small Hall plate 77 is mounted inside the ring and rotation of the disc varies the flux intensity therethrough. An arrangement using this principle and capable of sensing movements about two axes is described (Fig. 7). The eccentric disc arrangement senses movements of outer frame 96 about shaft 97. Inner frame 98 carries a magnetic member 82 having a partspherical surface 83 co-operating with a pair of similarly curved rings 84a, 84b through a constant air gap 94. A single magnet 90 drives flux through both systems in series. In the final embodiment (Fig. 8) the gyro-wheel 141 is mounted on a universal bearing 142 on shaft 143. Cylinder 144 on wheel 141 has a part-spherical end 145 which co-operates with two mutually perpendicular pairs of Hall plates 150, 151, 152, 153, mounted in cap 146. Body 149, body 144 or shaft 143 is permanently magnetized. The arrangement of Figs. 1, 2, 3 and 6 can be built into existing gyroscopes. It is stated that exciting current supplied to the Hall plates may be varied to compensate for temperature or other changes.