Constant Volume Buoyancy Compensation System

The present invention relates in general to underwater diving equipment and it relates in particular to a new and improved buoyancy compensation system for use by divers.

Buoyancy control compensation systems as commonly used in SCUBA diving generally employ a collapsible bag carried by the diver and into which air is supplied to inflate the bag to increase the buoyancy of the diver. An inherent disadvantage of these prior art systems is the fact that unless air is supplied to or removed from the bag the buoyancy compensation provided by the bag changes as the depth of the diver changes.

In the U.S. Pat. No. 3,161,028 there is described a buoyancy compensation system employing a rigid compartment attached to the diver and to which water is supplied or removed in order to adjust the overall buoyancy of the diver. Since the volume of the compartment remains constant irrespective of changes in ambient pressure as the diver descends or ascends, the buoyancy of the compartment does not vary in relation to depth. An inherent danger in using this prior art system is that should the diver descend with the mouthpiece in his mouth, the increasing differential between the ambient pressure and the pressure in the compartment can cause serious harm to the diver. There is, therefore, a need for a constant volume buoyancy compensation system which is safe, which is relatively light in weight, and which can be manufactured and marketed at a reasonably low cost.

Briefly, in accordance with the present invention there is provided a buoyancy compensation system comprising a rigid tank having a buoyancy chamber of constant volume to which ambient water is supplied to increase the effective negative buoyancy of a diver to whom the tank is attached. A pop-off type pressure regulator valve is mounted to the tank to prevent the chamber pressure from exceeding ambient pressure by a predetermined amount of say 2 p.s.i. A hand-held unit is connected to the buoyancy tank and to the diver's source of breathing air by means of two flexible hoses and includes a manually operable valve to enable the diver to control the supply of air to the buoyancy chamber. The hand-held unit also includes an emergency mouthpiece connectable to the buoyancy chamber for oral inflation and emergency breathing. The mouthpiece is also used for releasing air from the buoyancy chamber while water is being permitted to enter the chamber to increase the negative buoyancy of the diver. In accordance with an important feature of this invention pressure responsive means is incorporated in the hand-held unit to automatically operate the manually operable valve to connect the buoyancy chamber to the diver's air source to maintain the chamber pressure within a predetermined pressure differential of say 1.5 p.s.i. below ambient pressure thereby to prevent collapsing of the buoyancy tank.

Further objects and advantages and a better understanding of the present invention can be had by reference to the following detailed description, wherein:

FIG. 1 is an elevational view, partly broken away, of a buoyancy compensation system embodying the present invention; and

FIG. 2 is an enlarged, cross-sectional view of the hand-held control unit of the present invention, which unit is incorporated in the system of FIG. 1.

Referring now to the drawings and particularly to FIG. 1, a buoyancy compensation system 10 for use by SCUBA divers includes a hollow buoyancy tank 11 formed of a rigid plastic material such for example, as linear polyethylene, and having therein a buoyancy chamber 12 of constant volume. The rear side of the tank 11, as viewed in FIG. 1, is preferably contoured to fit the back of a diver and is contoured at the front as indicated at 13 to receive a pressure cylinder 14 containing a supply of pressured air for use by the diver in breathing underwater.

The underwater breathing system used by the diver is conventional and forms no part of the present invention. It includes a first stage pressure regulator 18 mounted to the top of the tank 14 for reducing the air pressure to 110 p.s.i. The regulator 18 as shown, has two outlet ports 22 and 23 for supplying air at this intermediate pressure to a second stage demand regulator 25 and to a flexible hose 26.

The demand regulator 25 includes a mouthpiece (not visible in the drawing) which the diver normally holds in his mouth at all times while under water. When the diver inhales, a valve in the demand regulator 25 automatically opens to supply breathing air to the diver. When the diver exhales the valve closes. As this description proceeds it will be seen that except for the use of air from the tank 14, the buoyancy compensation system of the present invention is entirely separate from the breathing system. Consequently, malfunction of one system will not adversely affect the other.

Mounted to the top of the buoyancy tank 11 is a normally closed pop-off type pressure regulator valve 28 which automatically functions to connect the top of the buoyancy chamber 12 to the ambient when the chamber pressure exceeds ambient pressure by, for example, 2 p.s.i. A spring-loaded normally closed valve 30 is mounted to the bottom of the buoyancy tank 11 and includes a bail type handle 32 connected to the valve member thereof to enable the diver to pull down on the bail to open the bottom of the chamber 12 to the ambient. Under normal conditions of use the valve 30 is opened by the diver when the buoyancy compensation is to be adjusted. This adjustment operation is more fully described hereinafter.

A hand-held countrol unit 34 is connected to the downstream end of the conduit 26, and a second flexible conduit 36 connects the control unit 34 to the top of the chamber 12. The control unit incorporates a manually operable valve for permitting the diver to increase the pressure in the buoyancy chamber 12 by interconnecting the conduits 26 and 36. Also included in the control unit is a mechanism for automatically operating the valve to supply air to the buoyancy chamber wherein the pressure therein falls below ambient pressure by a predetermined amount of say, 1 to 1.5 p.s.i. An emergency air mouthpiece 38 is provided on the control unit and when depressed opens a second valve to connect the mouthpiece to the buoyancy chamber. The mouthpiece 38 can thus be used in an emergency to breathe air from the buoyancy chamber 12 and it can also be used to permit the diver to blow air into the chamber 12.

Referring now to FIG. 2 for a more detailed description of the control unit 34. As there shown, the unit 34 includes a tubular body member 40 having a centrally apertured, internally disposed transverse wall 42. The wall 42 provides the valve seat against which a valve member 44 is biased by a coil spring 46. The mouthpiece 38 is tubular and has an external annular flange 48 to facilitate depression of the mouthpiece to push the valve member 44 away from the valve seat 42. It may be seen from the drawing that the stem of the valve member 44 is attached to a partition 50 in the mouthpiece 38 by means of a spring clip 52.

A tubular valve body comprising threadedly interconnected members 54 and 56 is sealably mounted transversely of the body member 40 in diametrically opposite openings 58 and 60. A valve seat member 62 is threaded into the outer end of the body member 54 and includes a transverse hole 64 connecting to a passageway 66 therein. The tube 26 is connected to a swivel head 67 sealably journaled on the body member 54 to supply air to the passageway in the valve seat member 62 via a transverse hole 68 in the body member 54.

A valve member 70 has a sealing disc 71 mounted in the end thereof for engagement with the annular valve seat 72 provided at the end of the valve seat member 62. A coil spring 74 is compressed between an annular flange 75 on the stem of the valve member 70 and a reentrant flange 76 at the end of the valve body member 56. The spring 74 thus biases the valve member 70 into a closed position.

In order to move the valve member 70 away from the seat 72 to couple air from the conduit 26 to the conduit 36 through a transverse hole 77 in the body member 56, a valve actuator mechanism 78 is mounted over the outer end of the body member 56. The actuator 78 includes a cup-like cylindrical housing 80 having a circular opening 81 into which the outer end of the member 56 extends. These parts are fixedly and sealably secured together by means of a weld 82. The outer end of the valve member 70 extends into the chamber 83 in the housing 80 through a central opening 84 in the flange 76. A lever 85 is pinned at one end to the valve member 70 and bears at its other end against a circular plate 86. A fulcrum piece 88 has a spherical bearing surface 80 which rests against the end surface of the body member 56. A flexible diaphragm and manual operating member 90 is secured to the plate 86 and sealably held in place across the open end of the housing 80 by means of a cover 92 which is threaded onto the housing. An enlarged central section 94 of the diaphragm 90 protrudes through a central circular opening 96 in the cover 92. It may thus be seen that the valve spring 74 urges the lever in a counterclockwise direction as viewed in FIG. 2. It should also be noted that the diameter of the opening 84 is substantially larger than the diameter of the adjacent portion of the valve stem whereby the pressure in the buoyancy chamber 12 is coupled to the actuator chamber 83. The valve seat member 62 has a screw driver slot 97 at the top to permit adjustment of the force required to move the valve member 70 away from the valve seat. Preferably the seat member 62 is adjusted so that an external pressure on the diaphragm which exceeds the pressure in the buoyancy chamber 12 by between 1 and 1.5 p.s.i., will cause the valve to open and thereby to interconnect the conduits 26 and 30 to increase the pressure in the buoyancy tank.

In using the system 10, before descending but while in the water, the diver will open the mouthpiece valve 44 and the water valve 30 to permit water to enter the buoyancy chamber until the desired amount of buoyancy compensation is achieved. He then releases both valves and preferably depresses the diaphragm 90 by exerting thumb pressure thereon. This pressurizes the buoyancy tank to the value determined by the relief valve 28 so that should the diver need to quickly increase his buoyancy he will simply open the water valve 30 to permit the pressure already in the chamber 12 to expel water therefrom.

Since the buoyancy chamber 12 has a constant volume, unless water is supplied to or removed from the chamber the buoyancy of the system will remain constant. However, the buoyancy of the diver himself, particularly if he is wearing a diving suit, will decrease as he descends in the water and the ambient pressure increases. Consequently, if neutral buoyancy is to be maintained some water will have to be released as the diver descends and this can be achieved by simply opening the water valve 30 so long as the pressure in the buoyancy chamber exceeds ambient pressure.

In order to ascend to the surface after completion of a dive, the diver will open the air inlet valve in the hand-held control unit and simultaneously open the water valve 30. The extent to which each of these valves is held open by the diver determines the rate of ascent.

While the present invention has been described in connection with a particular embodiment thereof, it will be understood by those skilled in the art that many changes and modifications may be made without departing from the true spirit and scope of the present invention. Therefore, it is intended by the appended claims to cover all such changes and modifications which come within the true spirit and scope of this invention.