US3908548A

US3908548A - Buoyancy system

Info

Publication number: US3908548A
Application number: US292593*[A
Authority: US
Inventors: Leon E Wedding
Original assignee: Individual
Current assignee: Individual
Priority date: 1975-09-30
Filing date: 1975-09-30
Publication date: 1975-09-30
Anticipated expiration: 1992-09-30

Abstract

1. A gas generator for use with a submersible buoyancy system comprising a cup having a top, a bottom and side walls, said top containing an opening adapted to be attached to the buoyancy system, a vent tube extending through said bottom to the proximity of said top, and a chemical liberating a gas by reaction with water packed between said side walls, said vent tube and said bottom, whereby water reaching said chemical through said vent tube liberates gas to block further entrance of water until the reaction with said chemical declines.

Description

United States Patent [1 1 Wedding Sept. 30, 1975 1 1 BUOYANCY SYSTEM [76] Inventor: Leon E. Wedding, 3813 17th St.,

NE. Washington, D.Cv 20018 221 Filed: Sept. 30, 1975 [21] Appl.No.:292,593

[52] US. Cl. 102/13; 9/8 R [51] Int. CIQ" F42B 22/10 [58] Field of Search 102/14. 7, 10. 13; 9/8

[56] References Cited UNITED STATES PATENTS 952.450 3/1911) Leon .i 102/14 2.642 693 6/1953 Broady 9/8 FOREIGN PATENTS OR APPLICATIONS 24,821 1914 United Kingdom .l 102/14 38.603 3/1915 Sweden 102/14 Primary Examiner-Verlin Pendegrass Attorney. Agent, or Firm-R. S. Sciascia; Q. E Hodges [57] ABSTRACT l. A gas generator for use with a submersible buoyancy system comprising a cup having a top, a bottom and side walls, said top containing an opening adapted to be attached to the buoyancy system. a vent tube extending through said bottom to the proximity of said top, and a chemical liberating a gas by reaction with water packed between said side walls, said vent tube and said bottom, whereby water reaching said chemical through said vent tube liberates gas to block further entrance of water until the reaction with said chemical declines.

3 Claims, 9 Drawing Figures US. Patent Sept. 30,1975 Sheet 1 of4 3,908,548

INVENTOR LEON E WEDDI N6 ATTORNEY US. Patent Sept. 30,1975 Sheet 2 of4 3,908,548

FIG. 2.

INVENTOR LEON E. WEDDING /3. 12- 2% ATTORNEYS 4 US. Patent Sept. 30,1975 Sheet3 of4 3,908,548 H INVENTOR LEON E. WEDDING ATTORNEYS US. Patent Sept. 30,1975 Sheet4 0f4 3,908,548

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INVENTOR LEON E. WEDDING ATTORNEYS A BUOYANCY SYSTEM The invention herein described may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to an underwater suspension system, and more particularly to a buoyancy system adapted to maintain itself at a predetermined depth below the surface of deep water.

In modern warfare it is frequently desirable to position equipment in the water a predetermined depth below the surface of deep water, a d to launch such equipment from either surface ships or from a submerged submarine. In launching a buoyancy system from a depth of several hundred feet in water, the buoyancy system is subjected to very high pressures which may cause improper operation or destroy the device entirely, and since it is usually desired to position the equipment within about forty feet of the surface, the system must operate to elevate the equipment to its proper operating depth. It is impractical to employ a rigid tank for buoyancy because of its size and weight, so that a non-rigid structure is required which can suc cessfully operate at water pressures of several hundred pounds per square inch. It is also necessary that the equipment maintain its proper depth for an extended period, and remove itself after its useful life is expended.

The device herein disclosed may be launched from any depth up to four hundred feet of water and may be launched from the flare tube of a submarine. The buoy ancy system is vented to the sea, thus equalizing the pressures inside and outside the nonrigid buoyancy tank, so that flexible impervious material may be employed therefor. The equipment to be supported has a constant weight and a gas generator having a substantially constant generating rate is employed to replenish the gas in the buoyancy tank, or balloon as it is called herein. A pressure responsive valve closing on increased pressure serves to maintain the buoyancy sys tem at a predetermined depth, and a parachute or damper serves to prevent rapid descent of the system thus insuring proper functioning of the control system.

It is an object of the present invention to provide a buoyancy system for equipment which will maintain a predetermined depth in deep water.

It is a further object of the present invention to provide a buoyancy system having a self-inflating balloon.

It is still a further object of the present invention to provide a buoyancy system having a self-inflating balloon and parachute to prevent rapid fluctuations in depth.

It is another object of the present invention to provide a buoyancy system having a self-inflating balloon with a pressure-responsive valve for controlling the depth thereof.

Further objects together with the attendant advantages of the present invention will be made apparent to those skilled in the art by reference to the following description in connection with the appended drawings in which FIG. 1 is an elevation view of the present invention in operation;

FIG. 2 is an elevation view partially in section of the buoyancy system of the present invention taken on line 2-2 in FIG. 1;

FIG. 3 is a detail view of the parachute of the present invention;

FIGS. 4a and 4b are detail views of the construction of the parachute of the present invention;

FIG. 5 is a cross-sectional view of the pressure responsive valve of the present invention taken on line 5-5 of FIG. 2;

FIG. 6 is a showing of the present invention packed for launching;

FIG. 7 is a detail view, partially in section, taken on line 7-7 of FIG. 6; and

FIG. 8 is a sectional view of the present invention as packed, taken on line 8-45 of FIG. 6.

Referring now to the drawings in which the same or corresponding parts are identified by the same number, there is shown in FIG. 1 an envelope or balloon 11 constructed of flexible impervious material. The material employed is preferably not resilient, so as to prevent changes in the volume of the balloon itself, although plastic and similar material may be employed if desired. A suitable material for the construction of the balloon 11 and the parachute 13 later to be described is rubberized fabric, since it may be readily folded into a small space and stored for extended periods of time. The balloon may be of any desired shape, but is illustrated herein as cylindrical with rounded ends. Couplings 15, I7, and 19 are sealed into the upper end, the lower end, and the side, respectively, of the balloon for purposes later to be described.

The parachute 13, best seen in FIGS. 2, 3, 4a and 4b is attached to the balloon 11 by means of the coupling 15, and is constructed of a series of radial ribs 21 pivotally connected to the under side of plate 23 and covered with a circular piece of flexible impervious mate rial 25. The plate 23 is provided with a plurality of guides 27 constructed by forming a plurality of depressions each adapted to receive one of the ribs 21, and the ribs are secured to the plate 23 by means of wires 29 passing through the ribs 21 and clinched through holes in plate 23. It will be readily apparent that the ribs 21 are free to pivot about the wires 29 below a horizontal position but are prevented by the plate 23 from pivoting upward past the horizontal position, so that the parachute has little effect on upward movement but greatly retards downward movement of the balloon 11. The parachute 13 is secured to the coupling 15 by means of the cap 31.

The gas generator employed with the present invention may be of any desired type, the major requirements being that it be lightweight and provide a substantially constant emission of gas over a considerable period of time. Because the weight of any gas is negligable with respect to the weight of water, the kind of gas employed is unimportant. The gas generator herein described is inexpensive to construct, rugged, and capa ble of producing a substantially constant flow of gas at high pressures, although many other types of generators may also be employed if desired.

As best seen in FIG. 2, the gas generator 33 comprises an outer cup 35 and a vent tube 37 extending through the bottom of the cup to a point near the top of the cup. The cup 35 is adapted to be sealed to the coupling 17 in the bottom of the balloon 11, and the volume between the inside of the cup 35 and the vent tube 37 is filled to within about 2 inch of the top of the vent tube with a chemical 39 which liberates a gas upon contact with water. Suitable chemicals include lithium hydride, calcium hydride, lithium metal, and others. In the present disclosure and for the purposes of illustration, lithium hydride is employed, since it liberates approximately 45 cubic feet of hydrogen at atmospheric pressure per pound of chemical and is capable of creating very high pressures.

The rate at which gas is generated depends in large measure upon the effective area of chemical exposed to the water. Thus the area of the surface of the chemical and the extent to which the chemical is compacted into its holder affect the rate of generation, and the addition of wax to the chemical will greatly retard its emission of gas. In the present generator, lithium hydride without wax compacted with a pressure of about four tons per square inch of surface area is employed.

Water entering the gas generator 33 through the vent tube 37 flows onto the lithium hydride, and immediately sets up a chemical reaction liberating hydrogen gas. The hydrogen gas liberated in the concavity between the cup 35 and the vent tube 37 forms a gas pocket which forces the major portion of the water away from the chemical 39 until the remaining water is exhausted in the reaction. The gas generator thus allows the lithium hydride to receive only a small quantity of water at any one time with which to react and the generation rate is thereby maintained substantially constant.

Gas liberated by the generator 33 rises through the water into the balloon ll, creating a pressure therein which forces water from the balloon through the vent tube 37 to increase the buoyancy of the system. It will be noted that the pressure within the balloon 11 is equal to the pressure on the outside, so that substantially no pressure is exerted on the impervious material.

The pressure-responsive valve 41 is screwed into the coupling 19 in the side of the balloon 11, the coupling being positioned so that the gas volume above the valve produces a slightly negative buoyancy in the suspension system including the supported equipment. The valve 41 comprises a sealed bellows 43 which is exposed to the pressure within the balloon, and contracts in length with increases in pressure. The bellows 43 is secured to the valve frame 45 by means of the threaded stud 47 fitting the threaded bore 49, and locked in position by means of the set screw 51. The other end of the bellows is provided with a threaded rod 53 which carries the valve plate 55 and the lock nut 57 threadedly engaged thereon. The valve plate 55 is provided with a raised lip 59 which contacts the valve seat 61 on the valve frame 45 when the valve is closed, and holes 63 are provided in the valve frame to allow passage of gas therethrough. The valve frame 45 is secured to the coupling 19 in any secure gas-tight fashion, such as threading.

The size of the holes 63 is proportioned to allow the escape of gas at the normal operating depth of the balloon 11 at a rate somewhat in excess of the generating rate of the gas generator 33, and the position of the valve plate 55 is adjusted on the threaded rod 53 to cause the raised lip 59 to close against the valve seat 61 at a depth slightly below the required operating depth of the balloon 11.

It is necessary at great depths that the balloon 11 be inflated immediately, even though the required replenishment rate of the gas generator is small. In order to provide an immediate supply of gas, lithium hydride crystals are placed within the folds of the balloon 11 when it is packed. Water entering the balloon in launching reacts with the chemicals to generate a considerable volume of gas which opens the balloon at once and provides a high positive buoyancy to cause the unit to rise rapidly. This feature is indicated in FIG. 8 by the reference numeral 64. An excess quantity of lithium hydride within the balloon is used to insure that the balloon will be completely filled under all launching conditions, since any excess gas will be discharged through the vent tube 37 without damage to the apparatus.

When the equipment is launched, the balloon l 1 rises and the water pressure declines so that the entrapped gas within the balloon expands in accordance with wellknown physical laws and part of the gas is exhausted through the vent tube 37. The parachute 13 tends to fold downward, so that little water resistance is created thereby, and the balloon 11 with the attached equipment rises rapidly toward the surface. At the point at which the valve 41 opens, additional gas is vented from the balloon, and the rise continues until a negative buoyancy is reached. The balloon 11 then begins to sink, opening the parachute 13, to create a large resistance, so that the descent is slow.

As the balloon l1 sinks, the water pressure on the entrapped gas increases which reduces the volume of gas therein. The gassing rate of the gas generator 33 must therefore replenish the gas in the balloon as well as the gas escaping from the valve 41. However, as the balloon 11 returns to its proper operating depth, the valve also closes to reduce the quantity of gas being vented, so that the volume of gas in the balloon increases at a faster rate. An equilibrium point is reached when the net buoyancy of the system is zero, and careful adjustment of the valve causes the equilibrium point to coincide with a valve opening which equalizes the amount of gas generated and the amount of gas vented.

It is desirable that the amount of gas released by the valve 41 be as small as possible, since a small gas loss reduces the required generating rate from the gas generator 33. However, rapid descents of the balloon 11 with correspondingly rapid increases in pressures which decrease the volume of gas entrapped in the balloon require high gassing rates to quickly supply the required volume of gas to the balloon. The parachute 13 therefore reduces the generating capacity required in the generating unit because it stabilizes the action of the buoyancy system by preventing rapid decreases in depth.

In order to launch the buoyancy system and its attached load from a submarine at a depth of several hundred feet, the entire assembly is packed in a cylindrical container 65 as shown in FIG. 6. In the present device, the cylindrical container 65 has a diameter of about three inches and a length of about 34 inches and comprises an upper compartment 67 containing the packed buoyancy system and a lower compartment 69 containing the equipment to be suspended from the balloon. The two compartments are joined together by a watertight joint at the juncture 71.

As best seen in FIG. 7, the lower compartment 69 is provided with a neck 73 having a reduced diameter adapted to extend within the end of the upper compartment 67. The exterior of the neck 73 is provided on its exterior with a groove 75 adapted to receive an O-ring 77 of natural or synthetic rubber material, and the end 79 of the upper compartment 67 is crimped over the O-ring 77. It will be apparent that the upper compartment 67 is securely fastened to the lower compartment under conditions of ordinary handling but may be separated by an axial force.

The buoyancy system of the present invention is packed into the upper compartment 67, as shown in FIG. 8. An explosive charge 81 is located in the upper end of the upper compartment 67 which upon detonation acts upon the disc 83 to force the two sections of the container apart and to eject the buoyancy system from the upper compartment. In order to insure that the container 65 is clear of the launching structure before explosive charge 81 is detonated, a delayed-action detonator 85 is used. The system for actuating the detonator 85 varies with the application in which the apparatus is used, and is not per se part of the invention, so that extensive explanation is not required. The detonator 85 is actuated by the launching of the container, and supplies a delay of about four seconds.

In order to prevent the force of the explosion from damaging the balloon l1 and the parachute l3, arcuate segments 87 are placed around the buoyancy system to transmit the thrust to the lower compartment 69. The arcuate segments 87 are maintained in place around the buoyancy system by the inner surface of the upper compartment 67, and drop off when the buoyancy system is ejected therefrom.

The lower compartment 69 of the container 65 houses the equipment to be supported by the buoyancy system and is attached to the buoyancy system by means of the rope 88. The rope 88 may be made of any substance which is relatively free from tendencies to kink or tangle, and as used herein is sash cord. The attachment of the rope to the buoyancy system and the lower Compartment 69 may take any desired form and is illustrated herein as

rings

90 and 92 attached to the gas generator 33 and the lower compartment 69 respectively.

For most applications, it is desirable to provide electric power to operate such apparatus as is to be used in the lower compartment 69, and for this reason, seawater batteries 89 are attached to the upper end of the lower compartment 69. Such batteries, as is wellknown to those skilled in the art, produce a potential when immersed in sea water and are inactive until so immersed. When equipped with such batteries, the apparatus is inactive until launched.

In operation, the container 65 is ejected from a suitable launching device, and in being so ejected, actuates the delayed action detonator 85. After the time delay of the detonator, the explosive charge 81 is detonated, which separates the two compartments of the container 65 and ejects the buoyancy system from the upper compartment 67.

When the buoyancy system is ejected into the water, water enters the gas generator 33 and the balloon 11 where it comes in contact with the lithium hydride, which immediately liberates hydrogen in large volume. The hydrogen thus liberated inflates the balloon, creating a positive buoyancy which causes the balloon to rise to its predetermined operating depth. As the balloon rises the pressure of the water surrounding it decreases in proportion to the depth, and the gas within the balloon expands accordingly, excess gas escaping from the vent tube 37.

When the balloon 11 reaches the setting of the pressure responsive valve 41, that valve opens to vent gas from the balloon. The balloon 11 will rise above its operating depth, and start to sink as the buoyancy of the system becomes negative, downward movement of the balloon causing the parachute 13 to open and retard the rate of descent. The valve 41 closes as the depth increases, and at the operating point of the valve 41, the gassing rate of the gas generator 33 equals the rate at which gas is vented by the valve, so that the balloon arrives at equilibrium.

When the lithium hydride is exhausted, the gassing rate of the generator 33 is reduced to zero and the balloon sinks to the bottom, thus automatically removing itself at the end of its useful life. The final descent of the device is rapid, because the increasing depth creates pressures which compress any remaining gas in the balloon to further reduce the buoyancy, so that the effect is cumulative.

For the purposes of illustration of one embodiment of the present invention, where it is desired to suspend a total weight of 12.2 pounds including the weight of the buoyancy system and to have the balloon operate at a depth of 20 feet, the balloon 11 has a length of 12 inches and a diameter of 5-% inches. The parachute 13 is 16 inches in diameter, the maximum positive buoyancy is 5.3 pounds, and the maximum rate of rise is 5 feet per secondv The gas generator 33 comprises a cup 35 having a depth of 4 inches and an inside diameter of l-3l/32 inches, and the vent tube 37 has an outside diameter /8 inches. The chemical charge consists of 50 grams of lithium hydride compressed under a total pressure of l 1 tons and having a generating life of 25 minutes during which time 5.5 cubic feet of hydrogen is produced.

The pressure responsive valve 41 has a throat /8 inch in diameter, and the holes 63 are /8 inch in diameter spaced 45 apart. The center line of the valve 41 is 6 inches from the top of the balloon 11, and the valve closes at 9 pounds per square inch. The spacing between the member 61 and the lip 59 at atmospheric pressure is approximately 0.07 inch.

If the projection of the vent tube 37 is not substantially /2 inch above the chemical, the gassing rate is increased until that projection is reached by consumption of the lithium hydride. The useful life of the buoyancy system is thereby shortened slightly but the device operates in a satisfactory manner. The depth of the lithium in the cup 35 is not critical.

It will be readily apparent to those skilled in the art that only a preferred modification has been described herein, and that many changes therein are possible without departing from the spirit of the present invention. It should be understood, of course, that it is intended to cover all changes and modifications of the example of the invention herein chosen for the purposes of the disclosure, which do not constitute departures from the spirit and scope as set forth in the appended claims.

What is claimed is:

l. A gas generator for use with a submersible buoy ancy system comprising a cup having a top, a bottom and side walls, said top containing an opening adapted to be attached to the buoyancy system, a vent tube extending through said bottom to the proximity of said top, and a chemical liberating a gas by reaction with water packed between said side walls, said vent tube and said bottom, whereby water reaching said chemical through said vent tube liberates gas to block further entrance of water until the reaction with said chemical declines.

2. A buoyancy system adapted to position itself at a predetermined depth after launching from a depth below said predetermined depth comprising, a collapsible cylindrical balloon, a gas generator comprising a bottom, side walls, and a top, said top having an opening communicating with and being sealed to said balloon, a vent tube attached to said bottom and extending through said generator to the proximity of said top, said generator containing a chemical reacting with water entering said vent tube to liberate gas continuously at a constant rate to inflate said balloon, said chemical being packed between said side walls, vent tube, and bottom of said generator, an opening in said balloon, a valve sealed to said balloon in said opening adapted to open at said predetermined depth, and a parachute attached to said balloon for retarding downward movement of said beacon after said predetermined depth has been reached thereby to allow an equilibrium to be reached between the rate of gas generation and the rate of gas release, whereby said beacon is maintained at said predetermined depth.

3. A buoyancy system adapted to position itself at a predetermined depth in water comprising, a collapsible impervious balloon having a top, side walls, and a bottom, a gas generator attached to the bottom of said balloon, said gas generator including a chemical reacting with water to continually emit a gas at a constant rate for inflating said balloon, a collapsible parachute attached to the top of and foldable about said balloon whereby said balloon and parachute will occupy a minimum volume in the collapsed position, said impervious balloon containing an opening adjacent its vertical median, and a valve responsive to water pressure at said predetermined depth sealed to said balloon over the opening in said impervious balloon for controlling the venting of gas from said balloon at substantially the rate of gas generation whereby said balloon is positioned substantially at a depth determined by said valve.