GB536031A - Anti-heeling device for ships, airships and the like - Google Patents

Abstract

536,031. Gyroscopic apparatus. MINORSKY, N. Nov. 3, 1939, No. 29332. [Class 97 (iii)] [Also in Groups XXXVIII and XXXV] The control of anti-rolling apparatus, for ships &c. in accordance with the response of known apparatus 89 sensitive to the angular acceleration of rolling is supplemented by a control in accordance with the angular acceleration of the ship's yawing motion (weather yaw) and in accordance with the speed of the ship. The apparatus may also control the rudder and reduce the weather yaw. Two oppositely rotating gyroscopes 1, 2 are pendulously mounted on precession axes in a frame carried in gimbals on the ship and restrained by springs 11-14. Studs 20,21 on each are coupled to a rod 26, Fig. 3, carrying coils 27, 28 so that these are moved in the fields of alternating current magnets 30, 31 to produce electro motive forces varying in proportion to the angular velocity of yaw. These are applied respectively to the grid circuits of amplifiers 32 so that opposed direct currents are produced in field coils 100, 101 of a generator 105 and in the primary windings of a transformer 42. The secondary windings therefore produce opposed currents proportional to the angular acceleration of yaw and after amplification energize opposed windings in an electrodynamometer 67 to re-act therein with a coil 65 energized in proportion to the ships speed by a generator 60. A control force proportional to the product of the angular acceleration of yaw and the ship's speed is transmitted from the electrodynamometer by any angle transmitting device, such as the Selsyn transmitter shown to one element 79 of a differential gear whereby movements proportional to the angular acceleration of rolling transmitted to another element 81 from an accelerometer 89 are algebraically added thereto to control a pump P controlling the rate of transfer of fluid between anti-rolling tanks T. The generator 105 actuates a motor 107 in accordance with the angular velocity of yaw to add to the rudder control, through a differential gear 108, a component to correct for the forced yaw. To adjust the zero of the antirolling control to compensate any asymmetry in the behaviour of the ship, manual adjustments 132, 133 may be applied to the stators of the Selsyn receivers 76, 83. To adjust the proportionality factor in the control a rheostat 68 may be provided. To enable a satisfactory control to be obtained when the roll period is long, a switch 40 may be thrown to give a control proportionate to the angular velocity of roll. Specification 408,796, [Group XXXIII], is referred to.