Buoyancy vest vent valve with reliable seating

Abstract

A vent valve for a buoyancy control device suitable for divers, where the valve may be opened by any combination of over-pressure, manual pressure relief or a powered means, where a force to a valve plug is applied by means of a spring that is constrained to prevent entirely lateral and angular movement but in which movement of the plug in the axis of the seat is unconstrained.

Claims

1. A device for venting gas from a diver's buoyancy compensation bladder, the device comprising: a valve plug configured to open or to close a valve seat, a spring configured to apply force to the valve plug to close the valve seat, a piston configured to apply force to the valve plug to open the valve seat, and a manual pull dump configured to open the valve seat manually, wherein the spring is fully restrained for more than 50% of its length, and the movement of the valve plug is constrained by a centering mechanism that prevents the valve plug from moving laterally or angularly while the centering mechanism allowing movement with the face of the valve plug parallel to the valve seat along the axis of a line extending perpendicular to the valve seat under any combination of over-pressure or manual pulling action using the manual pull dump, wherein the valve plug is configured to be biased to open the valve seat by a pneumatically or hydraulically powered means enabling powered actuation of the valve plug and/or by the manual pull dump enabling manual actuation of the valve plug and the valve plug is configured to be biased to close the valve seat by a counterforce created by or assisted by the spring, providing a first instantaneous flow rate from the powered actuation of the valve plug lower than a second instantaneous flow rate from the actuation of the valve plug through over-pressure relief or the manual actuation.

2. A device according to claim 1 wherein the valve plug is operable by the powered actuation to open first vent holes and the valve plug is operable by the actuation through over-pressure relief or the manual actuation to open second vent holes wherein dimensions of the first vent holes and the second vent holes define the instantaneous flow rates from the powered actuation of the valve plug and from the actuation of the valve plug through over-pressure relief or the manual actuation.

3. A device according to claim 1 wherein a piston rod of the piston is configured such that in case of a loss of electrical or gas power the valve plug is operable by the spring to close the valve seat while the valve plug remains operable by the manual actuation.

4. A device according to claim 1 wherein the valve plug comprises an outer valve plug and an inner valve plug.

5. A device according to claim 1 wherein the centering mechanism comprises a guide maintaining the valve plug such that the face of the valve plug is parallel to the valve seat at all times, wherein the guide is constrained by a cylinder that forms part of an outer cover of the device.

6. A device according to claim 1 wherein the spring is restrained by walls arranged at opposite ends of the spring.

Description

DESCRIPTION OF THE DRAWINGS

(1) For a better understanding of the present invention and the advantages thereof and to show how the same may be carried into effect, reference will now be made, by way of example, without loss of generality to the accompanying drawings in which:

(2) FIG. 1 shows a vent valve according to the present invention in the state where the valve is closed. The valve in this example and the following drawings includes a provision for powered actuation, which is desirable but not a necessary feature of the valve.

(3) FIG. 2 shows a vent valve according to the present invention in the state where the valve is open through manual actuation or over-pressure.

(4) FIG. 3 shows a vent valve according to the present invention in the state where the valve is open through an automatic actuation channel only.

(5) FIG. 4 shows a vent valve according to another embodiment of the present invention in the state where the valve is closed through an automatic actuation channel only.

(6) FIGS. 5-7 show the inflation and deflation of a buoyancy control device (BCD).

(7) FIG. 8 shows an alternative example of SUBA configuration.

(8) FIG. 9 shows an alternative example of SUBA as constructed.

DETAILED DESCRIPTION

(9) The invention will now be described in detail by reference to the aforementioned drawings and by use of example embodiments. Reference is made to a BCD bladder, The form of the bladder is not important: the present invention many be applied to many different types of bladders. The sole special requirement for the bladder to be used with the present invention is that the vent valves shall be arranged such that there is an open gas path from the gas in the bladder to one of the vents: at least one vent valve is required to fulfil this requirement depending on the range of diver attitudes for which the vent function is available.

(10) The vent valves in example embodiments shown in FIGS. 1 to 4 have a conventional manual pull dump (33) in addition to a pneumatically or hydraulically powered piston (27). The pull dump may be on a cord (35) or a lever. A spring (5) applies a pressure to a valve plug (29) to dose a seat (30), but which can be over-ridden by any combination of manual pull action, over-pressure or in these embodiments the powered actuation of the piston. The vent valve shown in FIG. 1 also comprises an inner valve plug 15; however, the vent valve according to another embodiment shown in FIG. 4 comprises only one main valve plug 29.

(11) A compression spring (5) is constrained by walls (8) for more than half its length, which prevents entirely the spring moving laterally (side to side in the drawings). The walls (8) can be arranged from opposite sides of the spring (5) or the walls (8) can have another configuration. The compression spring (5) may be a wire spring or a wave spring, or any other type of spring that applies a force to the valve plug (29) towards the direction of the seat (30).

(12) A compression spring (5) will apply an uneven force to the plug (29). Without further constraint, this would tend to allow the plug (29) to move at an angle with respect to the seat (30). To prevent that angular movement, the plug (29) is attached to a guide (9) that maintains the plug (29) such that the face of the plug (29) is parallel to the seat (30) at all times. In FIGS. 2 and 3 the guide (9) is constrained by a cylinder that forms part of the outer cover (1), and in FIG. 4 the guide (9) is constrained by the wall (8) that restricts the spring (5). It is highly preferable that the end of the guide remains outside the cylinder that it moves in, to prevent angular forces jamming the guide (9) in the cylinder.

(13) A hose (7) carrying the gas from the inflator to the actuators is preferably a narrow bore hose. Kynar hoses are available with a 0.8 mm bore and an outer diameter of 3.6 mm, which have the effect of limiting the maximum flow rate when used with typical BCD gas supply pressures to around 20 liters of gas flow per minute, and have a burst pressure exceeding the gas supply cylinder high pressure, such that if the first stage cylinder pressure regulator were to fail, then the hose (7) would not rupture, and therefore there is no risk of the bladder in the BCD being inflated suddenly. Moreover, use of a very small bore hose means that should the hose break, the flow rate into the bladder is much lower than the minimum vent rate if the diver uses the manual vent controls on the vent valves.

(14) A one-way valve (31) is preferably fined, and the one-way valve (31) is preferably of an umbrella flapper valve construction to provide a positive cracking pressure to prevent water ingress into the BCD when the valve is open.

(15) Vent valves with the features shown, namely an input (7), provide pressure which causes a piston (27) to move, opening a plug or stopper (29), allowing gas in the bladder to escape through a one-way valve (31). A manual pull-dump (33) is preserved in the preferred embodiment, allowing manual operation of the vent by the diver at any time. The pull-dump cord (35) may be singular or may be combined.

(16) A novel feature of the vent valves in the preferred embodiment is the use of a wave spring to apply even pressure to the plug (29) such that seats evenly.

(17) The use of the wave spring reduces the difference in the spring force across the plug (29) and hence reduces the angle it tries to adopt with respect to the valve seat (30). A wave spring is a type of compression spring built from a series of thin washers that have a wave-like profile. Compressing the washers, which are normally welded together, results in having a reactive force that is even around the circumference of the spring. A wave spring can also provide a greater extension for a particular spring force and spring bound size than a conventional wire compression spring, which can be advantageous in this application.

(18) A key feature of the vent valve is that the plug (29) is not firmly attached to the piston (27), such that pulling the plug (29) via the cord (35) causes the plug (29) to lift off the seat (30) without the piston (27) having to move. The seat at the top of the piston (27) need not be attached to the plug (29).

(19) In all FIGS. 1 to 4, the valve plug (29) is not fixed to the pneumatic piston rod (20): the rod can push the inner valve plug (15) in the embodiment in FIGS. 1 to 2 and the main plug (29) in FIG. 4, but does not prevent over-pressure from moving the plug to open the valve, nor prevent manual actuation opening the valve.

(20) In the case of FIG. 4, the valve plug (29) is limited in its movement by adjustment of an exterior cap to the valve to provide a limited or restricted instantaneous flow rate. In that embodiment the instantaneous flow rate through the over-pressure action is also limited in applications where that is desirable.

(21) In FIGS. 1 to 3 the automatic actuation of the valve does not move the main valve plug (29), but moves only the inner valve plug (15), through which gas flows. The instantaneous flow rate through that secondary valve comprising the inner valve plug (15) and seat is defined by choice of vent hole dimensions. This enables the automatic actuation of the valve to use a much lower instantaneous flow rate than that when the valve is opened manually or through over-pressure. For optimum automatic buoyancy control a ratio 8:1 or 16:1 is desired between the instantaneous flow rate in the over-pressure role and the instantaneous flow rate in the power (automated) actuation role.

(22) The pneumatic power may be provided by an arrangement of gas valves that apply a lower gas pressure, such as 9 bar, to the hose (7) to activate the vent valve, but which in the quiescent or inactive state opens the gas line to the BCD bladder. When the gas hose (7) is a small bore hose then the volume of the gas vented to the bladder may be kept to a negligible amount.

(23) An alternative to the pneumatic power to activate the vent valve is by use of a bellows containing a liquid such as alcohol or water or silicone oil, and pressure on the bellows by the user causes pressure to build up in the hose (7) and the valve to be opened. The spring bias to the bellows causes the liquid to pull back the piston when the pressure is removed. The pressure may be through a lever or directly on the bellows.

(24) The bellows or the hose (7) has a means through which gas can be drained and fluid topped up, but such means may be in the form of a nipple or filling point: there is no need for a hydraulic reservoir. During the filling process, sufficient provision should be made for the thermal expansion of the hydraulic liquid: this can be accommodated by a partial fill such that expansion of the liquid extends the bellows and contraction causes them to shrink in size, but leaving sufficient movement for the manual action.

(25) The bellows may be implemented in a variety of forms, including a thick walled balloon such as a silicone moulding, or it may be a telescoping moulding, or it may be a series of telescoping elements with O-ring seals.

(26) FIGS. 5-7 show the inflation and deflation of a buoyancy control device (BCD).

(27) FIG. 8 shows an alternative example of SUBA configuration.

(28) FIG. 9 shows an alternative example of SUBA as constructed.