GB2235659A - Multi-cycle sea-bed traversing system - Google Patents

Abstract

An inflatable float 41 Fig 8 comprises timer and pressure controls 45, 47, 48, 49 and automonous means for lateral movement e.g. hydrofoils 51 to enable underwater gear to be automatically lifted off the sea bed at intervals and moved to a new location. The gas for inflating the float may be generated by chemical means or galvanic action in dispensers 46 each having corrodible link actuation for different prescribed times. In another embodiment the gas is supplied from a pressurized cylinder 1 Fig 1 to an inflatable bladder 6 within a float chamber via a valve 7 controlled by links corrodible at different rates and which also control operation of a flooding valve 12. Deflation of the bladder can set to a predetermined depth by a valve 10. <IMAGE>

Description

MULTI-CYCLE SEA-BED TRAVERSING SYSTEM Underwater gear. such as fish traps. recording instruments, or bottom sampling equipment. has to be moved frequently over the sea bed, and this invention provides a means of doing this without having to use a boat.

The invention consists of an inflatable float, with timer means of controlling its inflation and deflation, together with means for moving it laterally. Inflation of the float may be by compressed air or by gas produced by chemical or electro-chemical means.

In the accompanying drawings of the preferred embodiment, Fig. 1 is an elevational view of the float system with a section of the float chamber.

Fig. 2 is a plan view on the section line A-A, illustrating one system for controlling inflation of the float.

Fig. 3 is a sectional elevational view, taken on the line B-B. showing a typical corrodable link and cam of the control system of Fig. 2.

Fig. 4 is an elevational view of part of the valve control mechanism of the gas source, with the flooding valve of the float chamber shown in section.

Fig. 5 is an elevational view of the same valve mechanism in the direction C-C.

Fig. 6 is a plan view of a hydrofoil sinker.

Fig. 7 is an elevational view of the same.

Fig. 8 is a sectional view of the float system when chemical generation of gas for flotation is used.

In Fig. 1, 1 is a cylinder containing air under pressure, held in a frame 2 by retaining pin 3. A string of fish traps, for example, can be attached to frame 3 at lug 4.

The upper end of frame 2 is attached to pressure-resistant float chamber 5, which contains an inflatable bladder 6.

Valve 7 controls the release of air from cylinder 1, and is actuated by arcuate movement of arm 8. Valve 10 is a standard item, actuated by ambient water pressure so as to control the deflation of bladder 6. Normally, valve 10 will open when ambient water pressure equals atmospheric pressure, that is, when the system reaches the surface.

However, it can be set to operate at any desired ambient water pressure, that is, when the system has risen to any desired depth. Air passes from cylinder 1 to bladder 6 through tube 11. Water can enter and leave chamber 5 through flooding valve 12, to the underside of which is fixed fork 13 which straddles arm 8.

As shown in Fig. 4. compression spring 14 normally keeps valve 12 in the open position. The relationship between fork 13 and arm 8 is shown in detail in Fig. 5. Rotatable stem 16 of valve 7 in housing 15, is fixed at right angles into arm 8 at its mid-point. Pin 17 in arm 8 helps to keep arm 8 and fork 13 in their correct relative positions.

In Fig. 3, cam 18 can move along guide rods 19, 19, under the influence of tension spring 20, unless restrained by corrodable link assembly 21. The movement of cam 18 is such that it displaces arm 8 in passing it, but at the end of its travel is completely clear of arm 8. An array of such cams, springs and links is mounted in frame 22, which in turn is mounted on frame 2. Cams on opposite sides of valve stem 16 also act on opposite surfaces of arm 8, as shown in Fig. 2, so that the force of every cam, irrespective of its position in the array, always acts so as to turn arm 8 arcuately in the same direction, which rotates valve stem 16 to open valve 7.

In Figs. 6 and 7, hydrofoil section 23 has attached to it booms 24, 24, carrying tailplanes 25, 25, and vertical fins 26, 26. Mounting bracket 27 attaches rope 28 to hydrofoil section '3.

Fig. 8 illustrates an embodiment of the invention in which chemically-generated gas is used instead of compressed air to inflate the float. In this, 41 is a length of tubing which need not have high pressure resistance, and which is permanently sealed at one end. 42 is a cap which screws on to one end of tube 41 to seal it by means of "0" ring 43. 44 is a removable dispenser rack on which are hung dispensers 45, 45, 45, each with corrodable link actuation for different prescribed times.

Dispensers of this type are disclosed in detail in my British Patent No. 1,295,961. 46, 46 are sealed pouches in dispensers 45, each containing a dose of appropriate chemical. Typical reactions for the production of gas are:- LiH + H O = LiOH + H Mg + 2H 0 = Mg(OH) + H (Mg-Ni couple).

2 2 2 As the pouches 46 are either vacuum-packed with the chemical, or also contain an inert liquid, neither they nor their contents are affected by ambient water pressure, however high this may become. Release of the chemical in these dispensers is by a mechanism for cutting the pouch open, which is actuated by failure of a corrodable link at a predetermined time. 47 is a valve which opens to admit water to tube 41 when ambient pressure is above internal pressure, and 48 is a valve which opens to release air, gas or water from tube 41 at a prescribed internal/ambient pressure differential. 49 is a valve which opens to vent the system completely when ambient pressure drops to a predetermined level, e.g., atmospheric pressure when the float reaches the surface. 50, 50 are corrodable links with a time to failure longer than that of the link controlling the penultimate cycle of chemical dispensing. When they corrode to failure, these links act to close valves 47 and 49 permanently. Hydrofoils 51, 51, are attached to tube 41 to give the system a horizontal component of motion, guided by a stabilising fin (not shown) as it ascends.

In operation, a string of items of gear such as fish traps on rope 28, attached at one end to the float at lug 4, and at the other end to the hydrofoil sinker at bracket 27, is laid on the sea bed from a boat in the usual way.

Since the valve to the compressed air source is closed, chamber 5 will be filled with water and bladder 6 will be compressed into a small volume bv the pressure of this water. After a predetermined time, the corrodable link 21 which has the shortest life will fail, permitting its associated cam 18 to move under the force of spring 20.

The resulting displacement of arm 8 turns valve stem 16, which opens valve 7 to permit air to pass from cylinder 1, through tube 11, to inflate bladder 6. When the pressure in bladder 6 exceeds that of the water outside the chamber, it presses upon flooding valve 12 and closes it.

This causes fork 13 to move downwards on to arm 8 and restore it to its starting position, which movement closes valve 7. With water displaced from the chamber, this now rises towards the surface, carrying the gear and hydrofoil sinker with it. As it rises1 the external water pressure drops and when this reaches the level where valve 10 is actuated, air is released from bladder 6, and water reenters chamber 5 through flooding valve 12, causing the entire system to sink again.

Because of its hydrofoil construction, however, the sinker does not fall vertically downwards, but "glides", thus pulling the attached gear horizontally. The gear will therefore land on a different part of the sea bed to that from which it was lifted by the float. After a further predetermined time the next corrodable link breaks to inaugurate a second cycle of lift and gliding fall, and so on until all links in the array have broken. For retrieval, the system may have a conventional marker float and line attached to it, or. for compactness, the marker float line may be held on a reel whose unwinding is controlled by a corrodable link assembly in which the link has a longer time to failure than the longest-lasting link in the release array.

It will be clear that the mechanism of bladder 6, valve 12, fork 13, arm 8 and valve 7 for isolating the gas source from the bladder, requires no setting for any particular depth. It will always operate as soon as pressure in the bladder exceeds ambient water pressure, whether this is high or low. Ignoring the small pressure required to overcome the force of spring 14, this means that the isolating mechanism can operate down to a depth where the ambient water pressure equals the residual pressure in the gas source after charging the bladder.

It can also operate when ambient water pressure is at its lowest, i.e. when the apparatus is at the surface, where pressure is atmospheric for all practical purposes, and at any intermediate depth.

In operation of the version of the embodiment in which chemically-generated gas is used, as the device sinks, water enters tube 41 through valve 47, and the air in the tube is expelled through valve 48. When each dispenser acts, the chemical released into the water generates gas, which expels water through valve 48 to generate buoyancy.

Excess gas is also bled off through valve 48 as the system rises through the water, and lateral movement is caused by hydrofoils 5t, 51. When it reaches its pre determined depth, which may be zero, i.e. the surface, all the residual gas is vented through valve 49, and the system sinks down to the sea bed once more until the next cycle commences. After the final dispense of chemical, the system remains on the surface, as valves 47 and 49 have been closed by the failure of their controlling corrodable links, 50, 50.

Alternative means of carrying the invention into effect, which do not go bevond the limits of its protection as claimed, include: All valves could be microprocessorcontrolled, and actuated by solenoid, or bv opening electrical circuits to impress a current on links made from material that is high in the galvanic series in sea water. Appropriate valves could be timer controlled instead of depending upon ambient water pressure. Since the speed of ascent could be established by calculation or experiment, such timed actuation could be related to a predetermined water depth, or the time interval after inflation could be such as to ensure that the gear will have reached the surface, i.e. zero depth. The valving of the system could also be arranged to leak gas at a predetermined rate.

Release of gas from the system could be used instead of or in addition to the hydrofoils attached to the float chamber or the hydrofoil sinker, to achieve lateral movement of the system. In the compressed air version, hydrofoils attached directly to the frame 2 could function in the same manner as those attached to tube 41 in the chemically-generated gas version. They would then cause lateral movement during ascent and fall in the same way as the hydrofoil sinker does during fall. Lateral movement could also be achieved by any form of independent power source, driving paddles or propellors, or reaction means.

A differential pressure valve could be incorporated in the compressed air version to bleed off excess pressure in the bladder as the apparatus rises through the water. This would enable container 5 to be more lightly constructed, as it would not have to be pressure-resistant to any significant extent.

In my corresponding United States patent application, Serial No. 509,016, for issue as a patent on August 29, 1989, the Examiner cited the following prior art: U.S. patents nos. 1,177,157: 2,520,562; 3,436,776; 3,570,437; 3,724,120; 3,738,046; 3,852,908; 3,864,772; 3,952,349; 4,034,693; 4,092,797; British patent nos. l,407,979; 1,424,527; German patent no. 2,324,709.

In prosecution, the issue was reduced to obviousness on the grounds of U.S. patent no. 3,952,349 (Erath et al.) in view of U.S. patents nos. 4,034,693 (Challenger) and 3,570,437 (Davis).

On appeal, the Examiner withdrew his reliance on Challenger and Davis in relation to Erath as not being fully combinable, and the Board of Appeals ruled in favour of applicant in terms of the Claim now submitted herewith.

Claims (1)

1. CLAIMS:

   1. An autonomous. multi-cycle sea-bed traversing system, comprising, in combination, flotation means wherein water can be displaced by gas, a source of gas under pressure for charging said flotation means, independent timer control means for opening said flotation means to said gas source at intervals, means for isolating said source from said flotation means when charging causes flotation, means for venting said flotation means when said system has risen to a predetermined depth and autonomous means for moving said system horizontally.