Patent ES-344938-A1 (ES)
Title: Depth Controller for a Subaqueous Seismic Detector Cable
IPC: G01V1/16
Filed: 1967-09-11
Abstract: During a marine seismic-prospecting operation a detector cable 20, Figs. 2 and 3, is towed by a craft (24), Fig. 1 (not shown), while being supported by a plurality of water-kites 30 so that it is kept substantially horizontal at a predetermined depth, each kite comprising a housing 32 furnished with fins 34 abaft a pair of hydroplanes 38, which are controlled by a flexible diaphragm 88 in accordance with the pressure of the ambient water. The housing comprises two sections (48, 50), Figs. 4 and 6 (not shown), which when brought together define a bore 46 wherein a portion of the cable is lodged and coupled to the wall 44 of said bore by a thrust bearing 64 and a plain journal hearing 68, these bearings being split to facilitate the assembly thereof about the cable. The diaphragm 88 is situated adjacent an opening 86 in the top of a tank 82 that is charged with compressed air through a valve 84, the upper side of the diaphragm being subjected to the pressure of water in a portion 118 of the housing that communicates with the ambient water through the bore 46 and contains a linkage system 100, 106 connecting the diaphragm to partially-rotatable arms 40 supporting the hydroplanes. A spring 112 minimizes hysteresis in the diaphragm and the pressure of the air in the tank 82 determines the depth at which the kite travels. The interior of the housing is partially filled with a buoyant material 116 and a ballasting weight 114, the latter in combination with the fins 34 serving to prevent the kite revolving about its longitudinal axis whenever the cable turns about its own axis. The housing may be made of plastics material e.g. nylon or P.T.F.E. The kite may be modified, Fig.- 7 (not shown), such that ballast (122) is located externally of the housing beneath the cable. A second embodiment, Fig. 8 (not shown), differs from that according to Figs. 2 and 3 in that the housing includes two tubular portions or arms (144, 146) situated above and below a pair of thrust bearings (134), respectively, which bearings engage with the cable 20. The lower arm (146) contains ballast (182) whereas the upper arm (144) carries a pair of hydroplanes (180), which are controlled by a spring-loaded piston (150) in accordance with the pressure of the ambient water communicated thereto through openings (158) in the associated arm. A spring (152) for loading the piston abuts an adjusting screw (154). In a third embodiment, Figs. 9 and 10 (not shown), the attitude of the kite relative to its longitudinal axis is corrected whenever the cable turns about its own axis by a reversible electric-motor (224) that is coupled to an epicyclic gear-train and is controlled by a pendulum (226), the gear-train comprising several pinions (210) meshing with a gear (208) attached to the cable. The pinions are mounted in bearrings (218) fixed to the interior surface of the housing, one pinion being coupled to the motor. The cable 20 engages with plain journal bearings (206) in the housing and the gear-train is contrived so as to transmit axial thrust from the cable to the housing. This embodiment is otherwise similar to either that shown in Figs. 2 and 3 or that according to Fig. 8. A fourth embodiment, Fig. 11, includes tubular portions containing thrust bearings, a section 304 containing ballast 308 and a section 302 containing passages 310, 314, 316. When the kite is towed by the cable 20, ambient water flows through the passage 310 into the passage 314 and/or the passage 316 depending upon the attitude of a horizontally-pivoted vane 318, which is connected by a shaft 320 to either a diaphragm of the kind shown in Figs. 2 and 3 or a piston of the kind provided in the second embodiment. The centrifugal action of the water in the passages 314, 316 directs the kite downwardly or upwardly accordingly.