Patent GB-681639-A (GB)
Title: Ship roll energy device
IPC: B63B27/18
Filed: 1950-09-12
Abstract: 681,639. Utilizing wave energy ; hydraulic couplings ; fluid-pressure servomotor-control systems. PATTERSON, J. C. Sept. 12, 1950, No. 22436/50. Classes 69 (i), 69 (ii) and 135 [Also in Group XXX] A work-to-energy converter in a ship is actuated, by means responsive to one part of the ship's roll cycle, to supply energy to a storage system, there also being means for varying the quantity of energy supplied by said converter per unit of work applied to it by the ship's roll. The invention is shown applied to the transference of materials between two ships, or from ship to shore (Fig. 3), in which the cable 12 connecting the two rolling ships, or a rolling ship and a remote point, is wound on a drum 50 connected by gearing to a work-to-energy converter in the form of a parallel piston "wobble-plate" hydraulic unit 54. The output lines 71, 72 from the hydraulic unit are connected to a hydraulic accumulator 68 via a piston valve 58, a line 60, a selector valve 64 and a line 66 and to a reservoir 95 via a line 61 and a selector valve 65. The energy-varying means comprises a stroke control unit 56 in the unit 54 having a spring-loaded piston connected to the line 71 and which may vary the angle of the wobble-plate so that as the accumulator pressure drops the stroke angle increases and the torque remains constant. In operation, a valve 97 is opened and the piston control valve 58 put in the mid-position whereby the lines 60, 61 and 71, 72 are isolated. The hydraulic unit 69 driven by a motor 70 is put into operation and the accumulator charged, the stroke control mechanism 89 reducing the angularity of the wobble-plate of the unit 69 as the accumulator pressure rises. The cable is then paid out by closing the valve 97 and putting the handle 75 of the control valve 58 in the right-hand position, thus allowing the unit 69 operating as a pump to drive the unit 54 as a motor and so rotate the drum 50. The control valve is then put in the mid-position while cable connection is established and the handle 75 then moved to the left so that on that part of the roll cycle when the cable is pulled out, the unit 54 acts as a pump and supplies oil to the accumulator and during the period when the cable is to be reeled in the unit 54 is supplied by the accumulator as a motor. During this transfer period the motor 70 is kept running as a standby. The "wobble-plate" motor may be fitted with a device to ensure that more oil is pumped during pulling out than is used in retrieving, the apparatus then comprising (Fig. 6) a stroke control device 106 normally urging the wobble-plate to a zero stroke position and a piston control valve 114 connected to the upper side of the device 106 and to the line 101 of the "wobble-plate" motor. When pulling-out, the oil pumped along line 101 closes the valve 117 so that pressure is applied via the line 115 to the plunger 119 and moves it upwards against the spring 120. The oil pressure is then applied via the line 113 to the device 106, thus moving the wobbleplate to the maximum stroke position. When retrieving, the oil flow in the line 101 is in the opposite direction, the valve 117 open and the "wobble-plate" therefore in the zero stroke position. The "wobbleplate" motor in the system may be replaced by a hydraulic unit of the radial type or the entire system may be operated by electrical means.