US3665884A

US3665884A - Submersible vehicle buoyancy control

Info

Publication number: US3665884A
Application number: US73276A
Authority: US
Inventors: Roy H J A Gustafson
Original assignee: Sperry Rand Corp
Current assignee: Sperry Corp
Priority date: 1970-09-18
Filing date: 1970-09-18
Publication date: 1972-05-30
Anticipated expiration: 1989-05-30

Abstract

A fail-safe electro-hydraulic control system varies the buoyancy of a submersible vehicle to facilitate variation of the vehicle''s operating depth by independent propulsion apparatus. A closedloop hydraulic circuit determines the proper degree of water ballast storage, simultaneously storing energy in a pressure tank for direct rapid fail-safe restoration of buoyancy to the vehicle in the vent of a system failure.

Description

United States Patent May 30, 1972 Gustafson [541 SUBMERSIBLE VEHICLE BUOYANCY CONTROL [72] Inventor: Roy H. J. A. Gustaison, Sea Clifi, NY.

[73] Assignee: Sperry Rand Corporation [22] Filed: Sept. 18, 1970 [21] Appl. No.: 73,276

[52] U.S.Cl ..l14/16E 511 ..B63g 8/00 [58] Field of Search ..1 14/16 E, 16 R, 235 B, 0.5 R; 9/8 R; 61/69 R [56] References Cited UNITED STATES PATENTS 863,532 8/1907 Hector ..1 14/16 E 2,972,972 2/1961 Allen ..ll4/l6E 3,204,596 9/1965 Fallon ..ll4/l6E Primary Examiner-Trygve M. Blix Attorney-S. C. Yeaton ABSTRACT A fail-safe electro-hydraulic control system varies the buoyancy of a submersible vehicle to facilitate variation of the vehicles operating depth by independent propulsion apparatus. A closed-loop hydraulic circuit determines the proper degree of water ballast storage, simultaneously storing energy in a pressure tank for direct rapid fail-safe restoration of buoyancy to the vehicle in the vent of a system failure.

11 Claims, 1 Drawing Figure 35c INCREASE 2 DECREASE FROM PRESSURE SUPPLY Patented May 30, 1972 201 4 DECREASE 24 :7 FROM 205 PRESSURE SUPPLY 209 104 1100 L i To SUMP INVENTOR R0) HL/A. GUSTAFSO/V A TTOR/VEY SUBMERSIBLE VEHICLE BUOYANCY CONTROL BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates generally to submersible vessels of the type including a capability for generally vertical descent or ascent in a body of water. The invention more particularly pertains to buoyancy control systems for such vessels for facilitating propulsion of the vessel to a selectable predetermined water depth and for its maintenance substantially at that depth.

2. Description of the Prior Art In the recent past, there has been intensive development of several types of oceanographic vessels for performing various work functions in the undersea environment, such as surveying, mineral and biological sampling, rescue, and kindred functions. Such undersea vehicles have included manned and unmanned submersibles of the self-propelled, towed, and otherwise remotely controlled types.

.Such vehicles have generally lacked stable and versatile means for buoyancy control. Since'efficient and safe control of buoyancy in substantially vertical descent or ascent is desired, techniques available for the control of more conventional military submarines are found to be inadequate, those techniques requiring a significant degree of longitudinal motion of the vessel. These and other techniques available suffer because of complexity and large size, weight, and cost of apparatus and often require the use of special, untried components. Such deficiencies feature attendant high costs of installation, maintenance, and repair.

Available buoyancy control techniques do not offer a capacity for rapid but accurately controlled change from one state of buoyancy to another and accordingly do not lend themselves to fully satisfactory fail-safe operation and to quick corrective response under conditions of partial or total failure of the control system or of its energy supply. Corrective response to a failure generally makes heavy demands upon the primary power supply of the vehicle which, under the circumstances of a serious failure, may already be faced with large demands upon its capacity as, for instance, by the vessel propulsion system.

SUMMARY OF THE INVENTION The invention is a fail-safe and efficient electrically-controlled hydraulic system for the determination of the buoyancy of a submersible vehicle in holding, ascent, descent, or emergency modes. Control of buoyancy is achieved by the intake or expulsion of ballast water from the vehicle by means of hydraulic forces applied against the external sea water through a flexible but impervious wall of an actuator in the form of a transfer barrier tank. The transfer barrier pressure tank stores sea water to a degree determined by a closed-loop hydraulic system operated by a constant speed, non-reversing pump. Energy is simultaneously stored in a pressure tank during normal operation of the closed-loop hydraulic system. Such energy is automatically available in the event of electrical or hydraulic failure for the purpose of expelling sea water from the barrier transfer tank and thereby for safely restoring the buoyancy of the vehicle.

BRIEF DESCRIPTION OF THE DRAWING The sole FIGURE is a diagrammatic representation of the novel hydraulic system, partly in cross section, and of its as sociated electrical control circuit.

DESCRIPTION OF THE PREFERRED EMBODIMENT The invention utilizes a closed hydraulic control system, using both air or other gasses and a suitable oil or other liquid as hydraulic fluid media, in cooperation with an electrical control system for the automatic adjustment of the buoyancy of an underwater vehicle or vessel. Control of buoyancy is achieved by the intake or expulsion of water ballast such as sea water from the vehicle by means not requiring longitudinal motion of the vehicle through the water.

A principal element of the control system, as seen in the sole figure, is a pressure vessel 1 which serves as an energy storage element, normally containing hydraulic liquid and a gas such as air or nitrogen under considerable pressure. Pressure vessel 1 will be spoken of hereinafter as the air-oil pressure tank 1 in view of the character of the fluids found most convenient for use therein, though it is to be understood that fluids other than air and oil may be used. Tank 1 may be constructed of metal, although spherical fiber glass tanks are found to be inexpensive, light in weight, and otherwise to be suitable, since they are known to withstand pressure as great as 5,000 pounds per square inch absolute (p.s.i.a.) in 12.5 inch diameter sizes, for example.

Energy stored in air-oil pressure tank 1 is supplied and augmented for use within the closed hydraulic system by a hydraulic liquid pump 17 in a manner yet; to be described. Pump 17 may be any of several conventional available types, such as the fixed volume, positive displacement, multiple piston, liquid pumps of the type manufactured by Vickers Division, Sperry Rand Corporation, Detroit, Mich., including Vickers type number MF-l0-39l l-25. The latter device has a rated output of substantially eight gallons per minute at 3,750 revolutions per minute.

Automatic control hydraulic liquid flow is performed in part, by a

series

8, 12, l3, l4, l5 and 24 of conventional balanced poppet vales. Such leakage proof valves are readily available on the market and include means for solenoid control of the position of a spring-retumed poppet valve armature so as to prevent or to permit fluid flow through the poppet valve. Valves 12, 13, 14, and 15, as will be seen, open in pairs according to the setting of selector switch 35.

A further principal element of the system is the transfer barrier tank 6 which performs as the controlled actuator for the system, it representing the actuator element which takes in or expels ballast water in the process of changing the buoyancy of the vehicle. The transfer barrier tank actuator 6 also serves to isolate the closed hydraulic liquid control system from the ballast water, preventing the corrosive action of, for example, sea water within the closed hydraulic system. As is seen in the figure, actuator 6 has a pressure-tight casing 48 with

apertures

25 and 26 at its respective ends.

Apertures

25 and 26 are not in direct mutual communication because the flexible ovate bladder 7 is sealed in leak-proof manner adjacent opening 25 so that only that opening communicates with the interior 47 of the bladder 7. The interior 47 of bladder 7 is filled with'a hydraulic fluid such as oil and its size expands or contracts according to the pressure of hydraulic liquid at input 25. The remaining volume 27 of case 48 is filled with ballast water. It is clear that other types of actuators may be employed, such as an actuator comprising a simple piston moving in a cylinder and driven by hydraulic fluid, one face of the piston being in direct contact with the sea water.

As previously noted, the invention is versatile in nature, being adaptable to use in a variety of kinds of submersible vehicles or vessels, towed or self-propelled, manned or unmanned. In such applications, the apparatus appearing below line AA in the figure will normally be aboard the vehicle, in some cases mounted largely on its exterior surfaces. A manned vehicle may have the apparatus above line A-A within its closed interior. On the other hand, an unmanned vehicle would generally have the apparatus above line A-A located near the ocean or lake surface, as on a ship such as a tender for the submarine. Electrical cables of sufficient length to permit the vehicle to submerge to a desired depth would connect the parts above and below line A-A in the latter instance.

The novel buoyancy control system may be applied in a submersible vehicle, for example, of the general type disclosed in the Gerald R. Keatinge patent application Ser. No. 9,759 for a Remotely Controlled Unmanned Submersible Vehicle", filed Feb. 2, 1970 and also assigned to the Sperry Rand Corporation. Application Ser. No. 9,759 discloses a remotely controlled submersible vehicle having a rigid truss framework suspended from a floatation sphere, three horizontally disposed members of the truss framework being arranged to form a triangular assembly about a vertically oriented center post affixed to the sphere. Hydraulically actuated propellors are mounted at each comer of the triangular assembly to provide motion control in as many as six degrees of freedom, depending on the relative magnitude and direction of the thrust generated by the respective propellors. In operation, power is supplied to the vehicle and commands transmitted thereto for propelling it and directing it to perform various assigned tasks through a tether cable connected from the vehicle to a manned surface or subsurface vessel or other control station.

In any event, all of the hydraulic apparatus, including the above mentioned

elements

1, 6, 8, 12, 13, 14, l5, l7, and 24, lies below line A-A of the figure and is found aboard the submersible vehicle. Assuming that the vehicle is provided with a central supply of hydraulic liquid under pressure, that supply or any other convenient supply may be used to drive pump 17 through the agency of a conventional hydraulic motor 18, which may also be of the multiple piston type, driving pump 17 through shafting 22 and flexible coupling 21. The central pressure source (not shown) is coupled to motor 18 through throttle valve 23 depending upon the open or closed state of solenoid 34 actuated balanced poppet valve 24. Solenoid 34 is operated by electrical power supplied via lead 210 from the active contacts associated with relay blades 32 and 33. Throttle valve 23 provides a convenient means for adjusting the speed of motor 18 to a desired substantially constant value. Valve 23 may be adjusted according to the speed of response desired of the hydraulic control system. It will be understood that pump 17 and motor 18 may be provided in the conventional manner with case drains so that sea water is excluded from their interiors.

Hydraulic pump 17 is adapted to supply hydraulic liquid from sump manifold 100 to a high pressure manifold 101. When the hydraulic control system is not demanding sufficient flow of hydraulic liquid, pump 17 may be relieved of working against excessively high back pressure by a conventional relief valve 19 (set, for example, to open at 2,000 p.s.i.g.) located in pipe 102 connecting manifolds 100 and 101 and permitting flow from manifold 101 to manifold 100. Under certain other conditions of operation of the hydraulic system, a tendency to force fluid flow in the opposite sense may prevail. To remove the undesired effect of such an oppositely directed pressure, an appropriately oriented conventional check valve 20 is placed in pipe 103 permitting flow from manifold 100 to manifold 101. High pressure manifold 101 may also be equipped with a conventional filter 16.

Pressure manifold 101 is connected through filter 16 to a port of the balanced poppet valve 12, whose second port is connected to pipe 104. The output of filter 16 is similarly connected to a port of the balanced poppet valve 13, whose second port is connected to pipe 105. It is to be understood that hydraulic liquid under pressure in manifold 101 which passes the opened poppet valve 12 may flow through pipe 104,

to the interior 47 of bladder 7 of the transfer barrier tank 6. Likewise, hydraulic liquid under pressure in manifold 101 may alternatively flow through the opened poppet valve 13 and pipe 105 to the interior of air-oil pressure tank 1, thus increasing the pressure of the gas therein and storing energy.

Sump manifold 100 is connected to a port of balanced pop pet valve 14, whose second port is connected to pipe 104. The sump manifold 100 is similarly connected to a port of the balanced poppet valve 15, whose second port is connected to pipe 105. It is to be understood that hydraulic liquid may flow through

poppet valve

12 or 14 relative to the transfer barrier tank 6 or relative to the air-oil pressure tank 1 when

poppet valves

13 and 15 are opened.

Pipes

104 and 105 are joined through

pipes

106 and 107 adjacent the air-oil pressure tank 1 and the transfer barrier tank 6 through certain series connected hydraulic elements. The

latter series elements include the normally closed balanced poppet valve 8, a conventional relief valve 9 set, for example,

to open at p.s.i.a.) and a conventional check valve 10.

The closed hydraulic system may be opened for filling first with a hydraulic liquid and then with the appropriate quantity of air or other gas to a desired pressure level by use of manual valve 4 in pipe 108 branching from pipe 105. Excess gas may be bled from the hydraulic system by opening the closed hydraulic system with valve 11, found in pipe 109 branching from pipe 107.

Certain pressure sensors aid in controlling the operation of the hydraulic system by measuring pressure and by opening and closing electrical contacts. These sensors include pressure sensor 2 which operates electrical switch 39, pressure sensor 3 which operates electrical switch 38, and pressure sensor 5 which operates electrical switch 43.

Sensors

2, 3, and 5 are respectively individually connected by

pipes

110, 111, and 1 12 so that they measure pressure proximate the air-oil tank 1.

The electrical control circuit cooperates with

switches

38, 39, and 43 and is supplied with electrical current from source 29 through the manual on-off switch 30. Closure of switch 30 supplies electrical power via lead 200 to the relay switch blades 32 and 33 and to the arm 35 of a first manual selector switch, and via lead 201 to solenoid 36 of poppet valve 8, holding it in its closed position. The blade of selector switch 35 may be manually placed on one of three

contacts

35a, 35b, or 350. To decrease buoyancy, contact 35a is selected and, to increase buoyancy, contact 35c is used. When no change is desired, contact 35b may be used. Contact 35a is coupled by lead 202 to the switch blade 43 associated with pressure sensor or pick off 5. Contact 35c is connected to the arm 37 of a second manual selector switch which has

contacts

37a and 37b. Contact 37a is selected if the vehicle is to be operated in an upper region bounded by the sea surface, as for instance, at depths between zero and 500 feet. On the other hand, contact 37b may be chosen for operation at lower water depths say, from 500 to 2,000 feet. Contact 37a is connected via lead 203 to the switch blade 38 associated with pressure pick off 3. Likewise, contact 37b is connected via lead 204 to the switch blade 39 associated with pressure pick off 2.

Switch 39 has

contacts

39a and 39b, contact 39a being connected to pilot light 31. Contact 39b is coupled by lead 205 to

leads

206 and 207 and thence respectively to

solenoids

41 and 42, respectively associated with

balanced poppet valves

12 and 15. Switch 38 has

contacts

38a and 38b, contact 380 also being connected to pilot light 31. Contact 38b is coupled via lead 205 to

leads

206 and 207 and therefore also respectively to

solenoids

41 and 42. In addition, contact 38b is connected by lead 205 through lead 211 to the solenoid 40 controlling relay blade 33. Switch 43 has contacts 43a and 43b, contacts 43a being coupled via leads 208 to solenoid 44 associated with relay switch 32. In addition, contact 43a is connected by lead 209 to

solenoids

45 and 46, respectively associated with

balanced poppet valves

12 and 13. The second contact 43b of switch 43 is connected to pilot or monitor lamp 28.

Operation of the system is initiated manually by closing the power switch 30. When the vessel is to be submerged, mode selector switch 35 is then placed on contact 35a, commanding a decrease in buoyancy of the vessel by operating solenoid 44 and

poppet valves

13, 14, and 24. Electrical power is thereby supplied via relay switch blade 32 and lead 210 to solenoid 34, opening poppet valve 24. High pressure hydraulic liquid is thus connected from the vessels main hydraulic pressure supply according to the setting of throttle valve 23 to drive the hydraulic motor 18. In turn, hydraulic pump 17 is driven at a substantially constant speed and is ready to supply hydraulic liquid under pressure as directed by

balanced poppet valves

12, 13, 14, and 15 so as to control the effective buoyancy of the undersea vessel.

With

poppet valves

13 and 14 open, pump 17 transfers hydraulic liquid from the interior 47 of the transfer barrier tank 6 through pipe 104, poppet valve 14, manifold 100, manifold 101, poppet valve 13, and pipe to the interior of the air-oil pressure tank 1. As hydraulic liquid is removed from the interior 47 of transfer barrier tank 6, ballast water enters the interior 27 of tank 6 via aperture 26 and the buoyancy of the vessel progressively decreases. This program stores energy within air-oil pressure tank 1 which energy is readily available for recovery at all times should a quick increase in the buoyancy of the vessel or surfacing be demanded. Pump 17 will continue to operate in this way, relief valve 19 performing in the usual-manner, until the setting of mode selector switch 35 is manually changed or until the operating pressure of pressure pick off 5 is reached (for instance, 2,0l5 p.s.i.a.) in the air-oil pressure tank 1. Should the latter event obtain, switch blade 43 is automatically moved to the contact 43b. Monitor lamp 28 is illuminated while relay armature 44 moves switch blade 32 so that poppet valve 24 is closed and hydraulic motor 18 is stopped. The energy stored in air-oil pressure tank is none-the-less instantly available should a command to increase buoyancy be executed by moving selector switch 35 to contact 35c.

It will be understood that the interior 47 of bladder 7 is initially filled with a hydraulic liquid or oil, minimizing the volume 27 available for intrusion of ballast or sea water. Displacing the hydraulic liquid or oil from interior 47 increases the volume 27 of ballast water to a value determined by the size of barrier tank 6 and the amount of hydraulic liquid or oil pumped from tank 6. Air-oil pressure tank 1 is a pressure vessel normally initially filled with air to atmospheric pressure or, otherwise, to an alternative pressure determined by the maximum desired operating depth of the submersible vessel. For example, the respective volumes of tanks 1 and 6 may be chosen to allow ballast or sea water intake sufficient to change the buoyancy of the vessel by 30 pounds and to give a pressure within the air-oil pressure tank 6 after transfer of hydraulic fluid from the transfer barrier tank of 2,015 p.s.i.a, In one application, such a pressure is sufficiently in excess of the sea water pressure on the vessel at a depth of 2,000 feet to insure return of the vessel to a positive buoyancy state, for example, upon failure of the electrical or hydraulic power supply systems.

Should it be desired to increase the buoyancy of the vessel in the normal manner, mode selector switch 35 is placed on contact 350 so that electrical power may be fed through switch blade 37 and lead 203 to switch blade 38 and through contact 38b and lead 205 and thence respectively via leads 206 and 207 to

solenoids

41 and 42, opening the respective

balanced poppet valves

12 and 15. Application of electrical power to lead 205 and thus to lead 211 permits solenoid 40 to move relay switch blade 33 to supply power, as before, to hold poppet valve 24 open, permitting motor 18 to drive pump 17, as before.

With balanced poppet valves 12 and open, hydraulic liquid is pumped from the air-oil pressure tank 1 through pipe 105, poppet valve 15, manifolds 100 and 101, poppet valve 12, and pipe 104 to the interior 47 of bladder 7 of the transfer barrier tank 6. As the interior 47 of bladder 7 fills with hydraulic liquid, ballast or sea water is expelled through aperture 26 and the vessels buoyancy increases, permitting the vessel to be raised even more rapidly toward the surface by propulsion means which may be operated independently of the present invention. Operation of pump 17 continues until the setting of mode selector switch 35 is changed or until the commanded pressure level is achieved in the air-oil pressure tank 1 as detected by pressure pick off 3. The actuation point of switch 38 operated by pick off 3 may be set, for example, at 15 p.s.i.a. Consequent movement of switch blade 38 to contact 38a permits

balanced poppet valves

12, 15, and 24 to close shutting down operation of the system. Motion of blade 38 to the contact 38a causes monitor lamp 31 to be illuminated, indicating to the observer that the initial condition of vehicle buoyancy has been restored.

In the foregoing discussion of the operation of the apparatus for increasing the buoyancy of the vessel, it was assumed that the depth selector switch 37 was manually placed on contact 37a. This setting of switch 37, it will be understood, determines operation of the system in the region between the ocean surface and a submerged depth, for instance, of 5,000 feet. Similar apparatus operating in an analogous manner may be employed for controlling the vessel at greater depths such as, for instance, between 500 and 2,000 feet.

Should it be desired to increase the buoyancy of the vessel when it is operated at a depth below 500 feet, the mode selector switch 35 is again placed on contact 350, while switch blade 37 is moved to contact 37b. In this manner, electrical power may be fed through switch blade 37 and electrical lead 205. The electrical power then travels, as before, via leads 211, 206, and 207 to

solenoids

41 and 42, causing the opening of

respective poppet valves

12 and 15. Application of electrical power to lead 205 and thus also to electrical lead 211 again permits the solenoid 40 to operate, moving relay switch blade 33 to supply power, as before, via electrical lead 210 to hold poppet valve 24 open, permitting motor 18 to continue to drive hydraulic pump 17. With

balanced poppet valves

12 and 15 open, hydraulic liquid is again pumped from the air-oil pressure tank 1 through pipe 105, poppet valve 15, manifold 100, manifold 101, poppet valve 12, and pipe 104 to the interior 47 of bladder 7 of the transfer barrier tank 6. Again, as the interior 47 fills with hydraulic liquid, ballast water is expelled through aperture 28 of tank 6. Consequently the vessels buoyancy increases, placing the vessel in condition to be raised rapidly toward the ocean surface by conventional means ordinarily employed to move the vessel along a generally vertical path.

Operation of hydraulic pump 17 continues until the setting of mode selector switch 35 is changed or until the pressure level commanded by the setting of depth selector switch 37 is achieved in the air-oil pressure tank 1 as detected by pressure pick off 2. The actuation point of switch 39 operated by pick off 2 may be set, for example, at US p.s.i.a. Consequent movement of switch blade 39 to contact 390 again permits

balanced poppet valves

12, 15, and 24 to close, shutting down operation of the hydraulic system. In addition, motion of blade 39 to contact 39a again causes the pilot lamp 31 to be illuminated or other monitoring means to be activated. lllumina' tion of lamp 31 indicates to the observer that the desired initial condition of vehicle buoyancy has been restored. It is seen that the presence of the two

pressure pick offs

2 and 3 and their associated circuits permits restoration of the system to one of two selectable initial pressure conditions during the increase-buoyancy cycle.

As has been seen, the novel buoyancy control system has significant features permitting flexibility of operation under various circumstances, including the storage of energy in airoil pressure tank 1 which is used to facilitate changes in buoyancy of the vessel. Of equal import is the adaptability of the same control system to afford fail-safe operation of the vessel under failure conditions. For example, a failure in the electrical system automatically closes any of

balanced poppet valves

12, 13, 14, or 15 which may be open and passing hydraulic fluid, but automatically opens the normally closed poppet valve 8, solenoid 36 failing to hold the valve armature 8a in its closed position against a spring which is a conventional internal part of valve 8.

Should electrical failure occur when the vessel is in a positive state of buoyancy, the above described state of

balanced poppet valves

8, 12, 13, 14, and 15 prevents any further intake of ballast or sea water into the interior 27 of barrier tank 6.

Should electrical failure occur when the vessel is in its neutral state of buoyancy, automatic conversion to positive buoyancy is assured. In the neutral state, the pressure within airoil tank 1 exceeds the surrounding sea water pressure. Electrical failure, permitting balanced poppet valve 8 to open, rapidly dumps that stored pressure through

pipes

106 and 107 into the interior 47 of barrier tank 6. Consequently, a rapid discharge of ballast water from the interior 27 of tank 6 comes about, abruptly increasing the buoyancy of the vessel.

Should a failure appear in the hydraulic system that prevents operation of pump 17, the buoyancy control switch blade 35 is simply placed on its inactive contact 35b. This event restores positive buoyancy of the vessel also by opening solenoid 36 controlled poppet valve 8, all other balanced poppet valves returning to the closed position. Again, hydraulic fluid is transferred from the air-oil pressure tank 1 to the interior 47 of barrier tank 6 and ballast or sea water is rapidly discharged from interior 27. Relief valve 9 is included between

lines

106 and 107 to permit retaining a 110 p.s.i.a. minimum initial pressure in the barrier tank 6 during the discharge cycle. Thus, the system may be automatically recycled upon reaching the surface without recharging pressure tank 1 with air.

Fail-safe operation is fulfilled even at maximum depths for the vehicle, being insured by the automatic operation of the buoyancy control system, in the event of either electrical or hydraulic failure. That automatic operation is ensured because the buoyancy control system fills air-oil pressure tank 1 to a pressure determined by the pressure setting of switch during the decrease buoyancy mode of operation. The quantity of ballast or sea water discharge by the buoyancy control system when a failure is experienced depends upon the pressure level available in air-oil pressure tank 1, the ambient sea water pressure, and the amount of ballast or sea water within the interior 27 of tank 6. Increased operating depth diminishes the quantity of ballast water discharged but, as the vessel rises toward the ocean surface, additional ballast water is discharged from tank 6. Finally, as the air-oil tank 6 reaches the selected initial ambient pressure condition, the maximum vessel buoyancy is restored.

It will be appreciated by those skilled in the art that various changes falling clearly within the true scope of the invention may be made. For example, it has been convenient to speak of sea water and of the ocean in describing operation of the invention, while it is apparent that the buoyancy control system may be successfully operated in other bodies of liquid. Only one operating depth range may be employed, or several may be added by the addition of pressure pick offs such as

sensors

2 and 3 and their associated circuits. Representative operating characteristics, such as representative pressure levels, have been cited with regard to the system and its components, but it is to be understood that such values are merely representative, and that other values may necessarily be chosen depending upon the nature of the submersible vehicle to be controlled.

While the invention has been described in its preferred embodiment, it is to be understood that the words that have been used are words of description rather than limitation and that changes within the purview of the appended claims may be made without departing from thetrue scope and spirit of the invention in its broader aspects.

1 claim:

1. Apparatus for controlling a submersible vessel comprismg:

hydraulically actuatable means for transfer of ballast liquid for changing the buoyancy of said vessel,

energy storage means containing a compressible gas,

hydraulic pump means, hydraulic valve means for permitting reversible hydraulic liquid flow between said hydraulically actuatable means and said energy storage means through said pump means,

means operating said hydraulic valve means for commanding a change of buoyancy of said vessel, and

means responsive to the pressure level within said storage means for operating said hydraulic valve means to prevent hydraulic liquid flow therethrough when said commanded change is substantially completed.

2. Apparatus as described in claim 1 wherein said means for transfer of ballast liquid comprises:

substantially rigid tank means having first and second port means,

expansible barrier bladder means within said tank means and having port means sealed in leak-proof communication with said first port means of said tank means,

said tank means and said barrier bladder means being so constructed and arranged as to permit transfer of ballast liquid through said second port means in substantial proportion to transfer of hydraulic fluid through said first port means without co-mingling of said liquids.

3. Apparatus as described in claim 1 wherein said energy storage means comprises pressure tank means adapted to store hydraulic fluid and a compressible gas under pressure.

4. Apparatus as described in claim 1 wherein said hydraulic pump means comprises:

unidirection hydraulic pump means having input and output port means, and

substantially constant velocity motor means for driving said unidirectional pump means.

5. Apparatus as described in claim 4 wherein said hydraulic valve means comprises:

first and second valve means each having first and second port means, said first port means being connected to said hydraulic pump output port means, and

third and fourth valve means each having third and fourth port means, said third port means being connected to said hydraulic pump input port means.

6. Apparatus as described in claim 5 wherein:

said second port means of said first valve means and said fourth port means of said third valve means are connected to said means for transfer of ballast liquid, and

said second port means of said second valve means and said fourth port means of said fourth valve means are connected to said energy storage means.

7. Apparatus as described in claim 6 wherein said means operating said hydraulic valve means for commanding a change of buoyancy of said vessel comprises:

electrical power source means,

means for supplying electrical power to said motor means,

manual switch means connected to said electrical power source means for selecting the polarity of said buoyancy change,

first circuit means connected to said switch means for actuating said first and fourth valve means for permitting liquid flow therethrough, and

second circuit means connected to said switch means for actuating said second and third valve means for permitting liquid flow therethrough.

8. Apparatus as described in claim 7 wherein said means responsive to the pressure level within said storage means comprises:

first pressure sensor means connected to said storage means, and

first switch means activated by said first pressure sensor means,

said first switch means being connected in said first circuit for deactivating said first circuit at a first predetermined pressure level.

9. Apparatus as described in claim 7 wherein said means responsive to the pressure level within said storage means comprises:

second pressure sensor means connected to said storage means, and

second switch means activated by said second pressure sensor means,

said second switch means being connected in said second circuit for deactivating said second circuit at a second predetermined pressure level.

10. Fail-safe means for use in apparatus of the type described in claim 1 for automatically providing an increase in buoyancy of said vessel in the event of power failure, comprismg:

hydraulic circuit means for by-passing said hydraulic valve means and said hydraulic pump means and directly connected to said energy storage means and to said ballast liquid transfer means,

hydraulic valve means included in said hydraulic circuit means, and

means for opening said hydraulic valve means in the event of said power failure for automatically causing rapid discharge of ballast liquid from said ballast transfer means.

11. Apparatus as described in claim 10 wherein means is ineluded in said hydraulic circuit means for preventing complete discharge of said storage means.

Claims

1. Apparatus for controlling a submersible vessel comprising: hydraulically actuatable means for transfer of ballast liquid for changing the buoyancy of said vessel, energy storage means containing a compressible gas, hydraulic pump means, hydraulic valve means for permitting reversible hydraulic liquid flow between said hydraulically actuatable means and said energy storage means through said pump means, means operating said hydraulic valve means for commanding a change of buoyancy of said vessel, and means responsive to the pressure level within said storage means for operating said hydraulic valve means to prevent hydraulic liquid flow therethrough when said commanded change is substantially completed.

2. Apparatus as described in claim 1 wherein said means for transfer of ballast liquid comprises: substantially rigid tank means having first and second port means, expansible barrier bladder means within said tank means and having port means sealed in leak-proof communication with said first port means of said tank means, said tank means and said barrier bladder means being so constructed and arranged as to permit transfer of ballast liquid through said second port means in substantial proportion to transfer of hydraulic fluid through said first port means without co-mingling of said liquids.

4. Apparatus as described in claim 1 wherein said hydraulic pump means comprises: unidirection hydraulic pump means having input and output port means, and substantially constant velocity motor means for driving said unidirectional pump means.

5. Apparatus as described in claim 4 wherein said hydraulic valve means comprises: first and second valve means each having first and second port means, said first port means being connected to said hydraulic pump output port means, and third and fourth valve means each having third and fourth port means, said third port means being connected to said hydraulic pump input port means.

6. Apparatus as described in claim 5 wherein: said second port means of said first valve means and said fourth port means of said third valve mEans are connected to said means for transfer of ballast liquid, and said second port means of said second valve means and said fourth port means of said fourth valve means are connected to said energy storage means.

7. Apparatus as described in claim 6 wherein said means operating said hydraulic valve means for commanding a change of buoyancy of said vessel comprises: electrical power source means, means for supplying electrical power to said motor means, manual switch means connected to said electrical power source means for selecting the polarity of said buoyancy change, first circuit means connected to said switch means for actuating said first and fourth valve means for permitting liquid flow therethrough, and second circuit means connected to said switch means for actuating said second and third valve means for permitting liquid flow therethrough.

8. Apparatus as described in claim 7 wherein said means responsive to the pressure level within said storage means comprises: first pressure sensor means connected to said storage means, and first switch means activated by said first pressure sensor means, said first switch means being connected in said first circuit for deactivating said first circuit at a first predetermined pressure level.

9. Apparatus as described in claim 7 wherein said means responsive to the pressure level within said storage means comprises: second pressure sensor means connected to said storage means, and second switch means activated by said second pressure sensor means, said second switch means being connected in said second circuit for deactivating said second circuit at a second predetermined pressure level.

10. Fail-safe means for use in apparatus of the type described in claim 1 for automatically providing an increase in buoyancy of said vessel in the event of power failure, comprising: hydraulic circuit means for by-passing said hydraulic valve means and said hydraulic pump means and directly connected to said energy storage means and to said ballast liquid transfer means, hydraulic valve means included in said hydraulic circuit means, and means for opening said hydraulic valve means in the event of said power failure for automatically causing rapid discharge of ballast liquid from said ballast transfer means.

11. Apparatus as described in claim 10 wherein means is included in said hydraulic circuit means for preventing complete discharge of said storage means.