Abstract:
The invention relates to a buoyancy device with a constant and adjustable volume intended for any submersible entity capable of submersion at various depth, and comprising at least one float with a flexible member and filled with gas, the pressure of which is adjusted according to the submersion depth, and such that: the membrane is elastic and defines a gas volume that varies according to the elasticity of said membrane and to the relative inner pressure of said volume relative to the outer environment pressure. An expander-discharge system is used for supplying and emptying the gas to or from the inner volume of the float.

Description:
FIELD 
       [0001]    The present invention relates to floatability devices having constant and adjustable volume. 
         [0002]    The technical sector of the invention is that of producing such adjustable floatability devices designed for any submersible entity capable of immersing to different depths, such as an undersea diver who must compensate at any given moment, either for an excess of weight so as not to sink, or a floatability surplus so as not to rise to the surface. 
       BACKGROUND 
       [0003]    Stabilisation buoys used in particular by autonomous divers are known which, when they change depth during diving, must compensate manually for the volume of their buoy, either by injecting air originating from the first-stage expander of their gas bottle, or by purging the buoy by acting on purge valves located at different places in the latter; this is necessary at each change in depth as the volume of air/gas of the buoy is modified with the variations in pressure associated with this change in depth and must therefore be adjusted permanently or otherwise not allow the diver to stabilise at the desired depth. 
         [0004]    In addition, since such a buoy is made from a supple bladder generally made of polyurethane, the air/gas is always located in its upper part, which makes movements by the diver carrying said buoy difficult and, when the latter is deflated, its form is generally not hydrodynamic. 
         [0005]    The problem posed is therefore to produce an adjustable floatability device in a predetermined range, at a preferred volume value which must then remain constant during change in depth without intervention of the operator, offering the latter a constant reserve floatability, irrespective of the ascending and descending shifts of the submersible entity to which the device is attached; and when this entity is the diver operator himself, this device must allow him ease of movement and must have the most hydrodynamic form possible. 
         [0006]    A solution to the problem raised is a floatability device having constant and adjustable volume designed for any submersible entity, capable of immersing to different depths, and comprising at least one float with a supple membrane filled with gas and whereof the pressure is regulated as a function of the immersion depth, and such that
       this membrane is elastic and delimits a gas volume which is a function of the elasticity of this membrane and of the relative internal pressure of said volume in relation to the external ambient pressure,   an expander-discharge system ensuring supply and purging of said gas to or from said internal volume of the float.       
 
       SUMMARY 
       [0009]    In a preferred embodiment, said float comprises a rigid base on which said supple membrane is fixed and held, the latter determining with said rigid base said gas volume of the float, and the expander-discharge is a regulator for supply and gas purge, such that the internal pressure of the latter in the volume of the float relatively relative to the external ambient pressure is quasi kept at a predetermined value corresponding to a preferred and therefore constant floatability volume. 
         [0010]    Also, according to the present invention, the material from which the elastic membrane is made is selected such that its module of elasticity remains quasi constant in the deformation zone, creating the preferred floatability volume, this deformation being a quasi monotonous and biunivocal function of the relative internal pressure of the float. 
         [0011]    Other particular features and characteristics of the present invention are specified within the scope of the description and figures hereinbelow. 
         [0012]    The result is a novel floatability device which automatically retains a constant volume at a value selected by the operator, such as a diver, irrespective of the immersion depth of the latter. 
         [0013]    Such a device can comprise several floats which can be distributed around a submersible entity, such as the diver himself, in such a way that when immersed their resulting centre of total thrust is quasi combined with the centre of gravity of said entity or of the diver, allowing him to make easier changes in position. 
         [0014]    The characteristics of the float according to the invention give it a hydrodynamic form, irrespective of its inflation volume and the design of the expander-discharge allows a decrease in size of purge valves relative to those of buoys of current constant volume, which, due to the fact that they operate at low differential pressure, require large diameters for air/gas to pass through. 
         [0015]    Other advantages of the present invention could be cited, but those cited hereinabove are already sufficient to demonstrate its novelty and interest. 
     
    
     
       DRAWINGS 
         [0016]    The description and attached diagrams illustrate embodiments of the invention but are non-limiting: other embodiments are possible within the scope of the reach and the extent of the present invention, such as in particular in the form and embodiment of floats and their base. 
           [0017]      FIGS. 1A and 1B  illustrate a device according to the invention as worn by a diver. 
           [0018]      FIGS. 2A to 2F  illustrate different views of a float according to the invention. 
           [0019]      FIGS. 3A and 3B  illustrate respectively a perspective and sectional view, along A, A′ of  FIG. 3A , of an expander-discharge according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    In the present description, it is considered that the submersible entity is a diver  19  carrying a bottle or gas or air reserve  32  on his back, such as illustrated in  FIG. 1B , capable of supplying, because of a first-stage expander  31   1  and an expander-discharge regulator  20 , different floats  11  connected in parallel such as the three illustrated in  FIG. 1 , one on the chest of the diver  19  and the two others on either side of the air tank  32 . 
         [0021]    The regulator  20  makes reference to the external ambient pressure  33  and, such as defined hereinbelow, regulates the differential pressure inside the floats  11  and said ambient external pressure hereinbelow. 
         [0022]    Once this differential pressure is regulated, the volume of the floats  11 , which can vary from 0 to 6 litres for example for pressure adjustable varying from 0 to 1 bar, remains constant, irrespective of immersion. 
         [0023]    For this, each float  11  comprises a supple elastic membrane  23 , fixed and held on a rigid base  25 . Said rigid base  25  is preferably convex and the elastic membrane  23  is arranged and pretensed against the convex face of this base  25  prior to any filling of gas or air. 
         [0024]    To ensure proper tightness between the elastic membrane and said base, the latter comprises at least one peripheral groove  26  which cooperates with a throat  22  of a counterflange  21  which is fixed on the rigid base outside the groove  26  by sandwiching the edge of said membrane  23 . 
         [0025]    The base, the membrane and the counterflange can be fixed by tightening bolts  34  passing through these three elements and without requiring strong tightening due to the groove-throat characteristics hereinabove. 
         [0026]    The initial tension of the membrane, preferably made of elastic high-limit and strong elongation elastomer, is calculated to let this membrane  23  work in a zone where its module of elasticity is almost constant or at the very least such that its deformation is a monotonous and biunivocal function of the pressure: the thickness and the mechanical characteristics of the membrane are selected to have any given volume at maximum outlet pressure, to the float  11 , selected for the regulator  20 . 
         [0027]    The air or the gas is injected between the convex surface of the rigid base  25  and the membrane via an inlet/outlet orifice  28  and a connection  30  connecting each float  11  to the expander-discharge regulator  20  so as to produce a predetermined internal volume  29 . 
         [0028]    The convex base  25  comprises stiffeners  27  in its concave external part dimensioned to prevent any deformation of the base under pressurisation. To improve tightness of the membrane  23 , made by moulding, the latter can comprise a bulge  24  which penetrates the throat  22  of the counterflange  21  in which it is crushed by the groove  26  of the base  25 . 
         [0029]      FIG. 2A  is an exploded view of a base, a membrane and a counterflange constituting a float  11  with a detailed view  2 B;  FIGS. 2C and 2D  illustrate the same elements as  FIGS. 2A and 2B  but assembled by a system such as screw bolts  34  or any other clamping system.  FIG. 2E  is a view of a float  11  in active position with air or gas blown in its internal volume  29 , and  FIG. 2F  is a bottom plan view of the concave part of the base  25  by way of example. 
         [0030]    According to  FIGS. 3A and 3B , the expander-discharge system  20  according to the invention is constituted by a single regulator block comprising a body or external envelope  1  constituted by several parts whereof a hollow central unit  1   b  of cylindrical form taking up the elements hereinbelow, and ends  1   a ,  1   c  screwed and closing this central part: in the latter the purge valve  7 , allowing gas to escape to the exterior  33  via the purge orifices  33   2 , from the interior of the float  11  via the connection  30  of the latter towards the orifice  30   2  of the expander-discharge  20 , is integrated into the pressure-adjustment piston  6  which bears the seat  9  of the purge valve  7 , and which also ensures control of the supply valve  2  in gas or air via the orifices  31   2  originating from the expander  31   1  and towards the inside of the float  11  via said orifices  30   2 ; the valve  2  and the orifices  31   2  being located in an end part  1   c  of the body  1 . 
         [0031]    Each purge valve  7  and feed valve  2 , comprising a joint solid with a face of a piston being supported against its closing seat, is compensated, that is, the internal surface delimited by said support seat on the face of the seal-bearing piston is equal to the surface of the face opposite the piston and subjected to the same downstream pressure because of a borehole made in said piston and making said two faces communicate, the upstream pressure being exerted only on part at least of the lateral faces of the piston. The effort required to open said valves depends neither on upstream pressure nor on downstream pressure, but only on the compression effort of the springs  16  and  17  which ensure tightness of said valves on their support seat. Said springs are selected with the weakest possible stiffness constants so as to reduce the adjustment error of the upstream and downstream differential pressure which will ensure opening of the valves: for example for a piston of 20 cm 2 , a spring compression force of 5 Newton represents an adjustment insensitivity of 0.025 bar. 
         [0032]    The helicoidal spring  16  is supported at one of its ends inside the piston  6  and at its other end on the purge valve  7 , which valve is limited in its displacement, caused by the thrust of the spring  16 , by a stop  10  solid with the body  1 , due to a screw  12  described hereinbelow and borne by the end part  1   a  of the latter opposite that of  1   c  bearing the valve  2 , and arranged to the side of the spring  8  defined hereinbelow. 
         [0033]    The helicoidal spring  17  is supported per se at one of its ends against the body  1  of the regulator block  20  and at its other end on the supply valve  2 , the seat  4  of said valve being solid with the body  1  of the regulator block  20 . 
         [0034]    A third helicoidal spring  8 , as mentioned hereinabove, is supported at one of its ends on a stop  13  solid with the body  1  of the regulator block  20  and adjustable by a roller  15 , and at its other end on the piston  6 , which piston being balanced on one side by its spring  8  and the external ambient pressure  33 , and on the other side by the inflation pressure of the float  11 . 
         [0035]    Accordingly, the operating mode of such an expander-discharge is such that air or supply gas arriving via the orifice  31   2  passes via the valve  2  to inflate the floats  11  via a chamber  18  closed by the piston  6 : the latter is therefore balanced by the action of the spring  8  supported on the adjustable stop  13  by the roller  15  acting on a screw  12  supported on a stop roller  14  and the hydrostatic pressure on one side and the action of the inflation pressure of the float on the other side. 
         [0036]    If during a change in depth, such as more substantial immersion, the pressure inside the float  11  becomes lower than the action of the spring  8  added to by the action of the hydrostatic pressure which has actually increased, the piston  6  moves with the rod  3  which pushes and causes opening of the balanced flush valve  2  and which admits air or supply gas into the float  11  until the equilibrium of the piston  6  recloses the supply or flush valve  2 . 
         [0037]    A stop  5  limits displacement of the piston  6  in the event of substantial imbalance in order to limit effort on the rod  3 . 
         [0038]    Inversely, such as when the immersion depth is decreased, if the pressure in the float  11  is stronger than the action of the spring  8  added to by the action of the hydrostatic pressure, which then has a diminished effect, the piston  6  moves in the other direction and the rod  10  which is fixed then blocks the balanced purge valve  7  which lets the air originating from the float  11  escape until the equilibrium of the piston recloses the purge valve  7 . 
         [0039]    The rods  10  and  3  are adjustable for adjusting the sensitivity of the expander-discharge  20  to the opening of the flush or supply and purge valves.