WO2004096635A1

WO2004096635A1 - Buoyancy body release device

Info

Publication number: WO2004096635A1
Application number: PCT/SE2004/000619
Authority: WO
Inventors: Peter Gordon
Original assignee: P & P Utveckling Ab
Priority date: 2003-04-26
Filing date: 2004-04-23
Publication date: 2004-11-11
Also published as: EP1618036A1

Abstract

A buoyancy body which is intended to float in water in a predetermined attitude and which comprises an inflatable enclosure, a source of gas under pressure such as a gas cylinder, and device for releasing gas from the source into the enclosure to inflate the body if the buoyancy body is immersed in water. A mechanism is provided which releases gas from the source if water enters a chamber. An aperture is provided in a wall of the chamber if the aperture is open and the chamber is immersed in water. A valve is provided to block the aperture unless the pressure outside the chamber exceeds the pressure within the chamber to a predetermined extent. The chamber is mounted on a portion of the body which is immersed in water when the body floats in the predetermined attitude. The chamber communicates with an expansion enclosure which is outside the inflatable enclosure, which is exposed to the environment outside the inflatable enclosure, and at least in part is located at a position remote from the chamber and above the chamber when the body floats in the predetermined attitude.

Description

BUOYANCY BODY RELEASE DEVICE

The present invention relates to a buoyancy body release device.

Buoyancy bodies such as lifejackets, liferafts, buoys etc are well known which comprise an inflatable enclosure, a source of gas under pressure, and a mechanism for releasing gas from the source into the enclosure to inflate the body. Such buoyancy bodies are known which are automatically actuated when immersed in water. An automatically actuated buoyancy body of this general type is described in European patent specification EP0808271.

The buoyancy body described in the above European patent has an inflatable enclosure within which a gas cylinder is housed. The gas cylinder is connected to a gas release control mechanism defining a chamber. An aperture is defined in a wall of the chamber. If the aperture is open and the mechanism is immersed in water, water enters the chamber and dissolves or otherwise degrades a water degradable element which results in the release of gas from the gas cylinder into the inflatable enclosure.

Normally the aperture in the chamber wall is closed by a valve. The valve will open however if a relatively small differential pressure is applied to it such that the pressure within the chamber is lower than the pressure outside the chamber. Such a pressure differential can be created when the device is submerged. In theory when the device is submerged the water pressure outside the chamber will be sufficient to overcome the pressure within the chamber, resulting in the valve opening and admitting water to the chamber to commence the gas release process. In practice however the valve does not always open in a reliable manner when the buoyancy body is immersed.

For the valve to be exposed to the appropriate differential pressure as a result of the immersion of the buoyancy body, the pressure within the chamber must be lower than the pressure immediately outside the chamber. Buoyancy bodies are intended to assume predetermined attitudes when immersed in water. In the case of a lifejacket for example the jacket is designed to hold the user's head above water with the user's waist well beneath the water. If the chamber and associated valve are located so as to be adjacent the user's waist, then the upper part of the jacket should be exposed to a considerably lower hydrostatic pressure than the valve itself. Providing pressure within all parts of the inflatable enclosure is equalised, the pressure in the chamber will be equal to the lowest pressure to which the inflatable enclosure is exposed, given that the enclosure extends over the user's shoulders. It would be expected therefore that the required differential pressure will appear across the valve. Unfortunately this does not occur reliably. Sometimes the inflatable enclosure is partly filled with air and air cannot be readily displaced away from the chamber adjacent the valve. It is also possible for the flow of air through the inflatable enclosure to be so restricted as a result of tight packing of the enclosure that the pressure behind the valve is substantially equal to the hydrostatic pressure local to the valve. If this occurs the valve will not open.

It is an object of the present invention to obviate or mitigate the problems outlined above.

According to the present invention, there is provided a buoyancy body which is intended to float in water in a predetermined attitude, comprising an inflatable enclosure, a source of gas under pressure, and means for releasing gas from the source into the enclosure to inflate the body, the gas releasing means comprising a chamber in which a mechanism is provided which releases gas from the source if water enters the chamber, an aperture being provided in a wall of the chamber such that water enters the chamber if the aperture is open and the chamber is immersed in water, a valve being provided to block the aperture unless the pressure outside the chamber exceeds the pressure inside the chamber to a predetermined extent, and the chamber being mounted on a portion of the body which when the body floats in the predetermined attitude is immersed in water, wherein the chamber communicates with an expansion enclosure which is outside the inflatable enclosure, which is exposed to the environment outside the inflatable enclosure, and which at least in part is located at a position remote from the chamber and above the chamber when the body floats in the predetermined attitude.

Given that the expansion chamber is outside the inflatable enclosure, the pressure within the inflatable enclosure adjacent the chamber has no effect on the opening and closing the valve. Thus the valve will open in a reliable manner whenever it is immersed with the buoyancy body in the expected predetermined attitude.

The expansion enclosure may be an inflatable bladder, and the bladder may be located in an open body, for example a rigid or flexible open-ended tube. The open- ended tube prevents the bladder being compressed so as to obstruct airflow away from the chamber. Alternatively or in addition the bladder may be internally and/or externally reinforced to prevent it being flattened, for example by the helical member.

The bladder may be located at the position remote from the chamber and connected to the chamber by a connecting tube. Alternatively the bladder may be elongate and extend between the remote position and the chamber. The bladder may be incorporated in for example a lifejacket between the inflatable enclosure which defines the flotation device of the lifejacket and a lifejacket outer cover, or could be incorporated in the form of beading in the lifejacket outer cover, for example in beading extending around the outer periphery of the lifejacket cover from the chamber.

A moisture sensitive indicator may be located within the chamber so as to be visible through a transparent window in the chamber wall. The indicator may be arranged so as to change colour if the level of humidity within the chamber exceeds a predetermined level.

A removable cover may be provided to selectively seal the aperture so as to prevent automatic inflation.

The gas source may be a cylinder of pressurised gas, the cylinder having a seal which may be punctured by a plunger displaceable by a spring. A water sensitive member prevents displacement of the plunger unless water enters the chamber. The spring may be a compression spring arranged coaxially with the plunger. The plunger may be retained in position by a bobbin which bears against the support member, wetting of the bobbin causing the release of the plunger. A portion of the plunger may extend to a position outside the chamber so that the position of the plunger can be visually checked.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic representation of a known automatically inflatable lifejacket;

Figure 2 illustrates circumstances in which inflation of the known device of Figure 1 may not occur reliably;

Figure 3 is a front partially cut away view of a first embodiment of the present invention;

Figure 4 is a schematic representation of the gas release mechanism shown in Figure 3;

Figure 5 shows the gas release mechanism of Figure 3 before the device is immersed in water;

Figure 6 shows the gas release mechanism of Figure 3 after the device has been immersed in water but before inflation of the lifejacket;

Figure 7 illustrates an alternative gas release mechanism to that shown in Figure 3;

Figure 8 illustrates a still further modification to the gas release mechanism of Figure 3;

Figure 9 illustrates a second embodiment in accordance with the present invention;

Figure 10 is a perspective view of the embodiment of Figure 9 assuming it had been severed in the plane indicated by line 10-10 of Figure 9;

Figure 11 illustrates a detail of the structure shown in Figure 10; and

Figures 12 and 13 illustrates an alternative arrangement to that illustrated in Figures 10 and 11.

Referring to Figure 1, this schematically represents a person wearing a lifejacket 1 which has not yet been inflated with the wearer's body in a substantially vertical attitude. The lifejacket supports an automatic inflation device 2 which is located in a lower portion of the lifejacket so that in the attitude illustrated the device 2 is exposed to a hydrostatic pressure represented by the head of water h. Pressure behind the device 2 will be the pressure within the inflatable enclosure incorporated in the lifejacket 1 and therefore that pressure might be expected to correspond to the pressure in the upper portion 3 of the lifejacket. This may not be the case however as the lifejacket may have been very tightly packed so that there is no, or only limited, communication between the device 2 and the portion 3 of the jacket. Furthermore, if the jacket has been previously inflated and then insufficiently deflated it may be that the jacket will retain some air. If so the wearer may assume the attitude illustrated in Figure 2 where it can be seen that the device 2 is only just immersed in the water and the retained air will create a positive pressure in the uppermost portion of the lifejacket 1. Therefore the head h is very limited and that head may be insufficient to open a hydrostatically-operated valve incorporated in the device 2, when acting against the positive pressure retained within the uppermost section of the lifejacket.

Referring now to Figure 3, this illustrates a first embodiment of the present invention. The user 1 wears a generally U-shaped lifejacket having an outer cover 4. Part of the outer cover on the left-hand side of Figure 3 has been removed to expose an inflatable bladder 5. That bladder is in use inflated with gas from a cylinder 6. The cylinder 6 is outside the bladder 5, as is a gas release mechanism to which the cylinder is connected and a tube 7 which extends to an expansion bladder 8 located within a rigid open-ended tube 9.

Referring to Figure 4, this shows a gas cylinder and gas release mechanism shown in Figure 3 in greater detail. The wall of the bladder 5 has a gas entry opening defined by a rubber nipple 10 which incorporates a one-way valve 11. The valve 11 communicates with the interior of a housing 12 into which the cylinder 6 is screwed. A rod 13 extends axially along the housing 12, a sharp tip 14 of the rod 13 being aligned with a sealed end of the cylinder 6. If the rod 13 is moved upwards from the position shown in Figure 4, the tip penetrates the seal in the cylinder and the contents of the cylinder is then delivered to the interior of the bladder 5 as indicated by arrow 15.

The rod 13 may be manually driven upwards by pulling on a handle 16. Alternatively however the rod 13 could be driven automatically by a mechanism comprising a plunger 26, a plunger drive spring 17, a support 18 and a water- degradable bobbin 19.

In the position shown in Figure 4, the bobbin 19 encircles and grips the plunger 26, holding it against the force of the compressed spring 17, which is pressed into a circular opening defined in the support 18. If however the bobbin 19 is exposed to water it will lose its structural strength and will no longer be able to resist the axial force applied by the spring 17. As a result the plunger 26 is released and will be driven upwards against the end of the rod 13, which, in turn, forces the sharp tip 14 into the seal of the cylinder 6, releasing the gas into the lifejacket bladder 5.

A transparent window 20 is provided in an outer body 21 extending around the bobbin 19 to enable visual inspection of the state of the bobbin. The bobbin is enclosed in a chamber defined by the outer body 21 and a diaphragm valve 22 which is biased downwards in Figure 4 by a relatively weak spring 23 that is located between the outer body 21 and the bobbin support 18. If however the device of Figure 4 is immersed in water such that the hydrostatic pressure outside the chamber exceeds the pressure within the chamber to an extent sufficient for the valve 22 to open, water will enter the chamber, contact the bobbin 19, and cause release of the plunger 26. The pressure within the chamber is equal to the pressure within a passageway 24 that communicates with the chamber and with the tube 7 of Figure 3.

Figure 5 shows the arrangement of Figure 4 from a different angle before the device is immersed in water. Figure 5 also shows a lever mechanism 25 which is actuated by pulling on the handle 16 so as to manually drive the tip 14 of rod 13 into the cylinder 6. It will be seen that in the condition shown in Figure 5 the expansion bladder 8 is substantially empty. In contrast, when the device is immersed as shown in Figure 6, water enters the chamber occupied by the bobbin 19, displacing air from the chamber around the bobbin 19 through the tube 7 so as to inflate the bladder 8. Given that the bladder 8 is exposed to a relatively low pressure as it is located at a relatively high level compared with the diaphragm valve 22, the hydrostatic pressure necessary to cause the valve 22 to open is reliably available. Figure 6 shows water in contact with the bobbin 19, but before the bobbin has reacted to contact with water so as to release the plunger 26.

It will be noted that the plunger 26 has an end remote from the cylinder 6 which projects through a seal 27 to the exterior of the device. Thus a simple visual inspection of the unit will indicate whether or not the plunger 26 is in its correct position as shown in Figure 4. If the bobbin 19 is dissolved, the plunger 26 will drive the tip 14 of rod 13 into the seal of the cylinder 6 and the plunger end 26 will be retracted into the assembly. It will be appreciated that by appropriate selection of the material from which the bobbin 19 is manufactured the bobbin can be caused to dissolve in a matter of a few seconds, ensuring rapid inflation of the lifejacket.

Figure 7 is a view similar to Figure 4 showing the detail of the gas release mechanism. In addition however a strip 28 of relative humidity indicator paper has been located behind the window 20. For example a paper could be used which would change from blue to pink if exposed to a humidity of greater than 40%. This would give a ready indication as to whether or not the device was in a condition such that the bobbin 19 might be about to degrade and would therefore need replacing.

Referring to Figure 8, this shows a removable cover 29 screwed over the diaphragm valve 22 so as to prevent any possibility of water penetrating the chamber in which the bobbin 19 is housed. Such a cover might be used for example in circumstances where a wearer of the lifejacket wished to be sure that automatic inflation could not occur, for example, personnel at risk of ditching in a helicopter would not want their lifejackets to inflate automatically for fear of the lifejackets trapping them in the sinking helicopter. Accordingly users could be issued with covers which could be rapidly removed or placed in the position shown in Figure 8 as desired.

Referring now to Figures 9, 10 and 11, an alternative embodiment of the invention will be described. Whereas in the embodiment of Figure 3, the expansion vessel was a bladder located at a point remote from the automatic actuating mechanism and connected to the mechanism chamber by a tube, in the arrangement of Figures 9 to 11 the expansion enclosure is a tubular bladder extending from the actuating mechanism chamber passageway 24 and mounted all around the outside of the lifejacket cover.

Referring to Figure 9, the jacket 30 has a "beading" edge 31 which is in the form of an open-ended perforated tube extending around the entire periphery of the jacket cover. The beading is tubular and has within it a tubular expansion bladder. The expansion bladder is connected to an actuating mechanism 32 which may be of the type illustrate in for example Figure 5 but with the passageway 24 connected to the bladder within the beading 31 rather than to a tube 7.

Figure 10 represents a portion of the jacket 30 which has been cut through to show the internal structure. The beading 31 extends along one side of the cover 30, the cover 30 housing the main lifejacket bladder 33. The bladder 33 corresponds to the bladder 5 in Figure 4 and is the main inflation body of the lifejacket.

The beading 31 houses a tubular expansion bladder 34 along the length of which extends a reinforcing member 35 in the form of a helix of plastics material. This is best illustrated in Figure 11. The helix 35 ensures that the bladder 34 cannot become so flattened as to prevent air flowing through it from the passageway 24 (see Figure 4).

The beading tube 31 is open ended but is also perforated along its length such that the pressure within the bladder 34 will assume the lowest pressure to which any part of the bladder is exposed. The helix 35 prevents hydrostatic pressure causing the portions of the bladder which are at a relatively great depth within the water from collapsing in on themselves. Thus a reliable route is provided for air to flow from the chamber into which water penetrates past the diaphragm valve.

As an alternative to the arrangement illustrated in Figures 9 to 11 in which a tubular bladder assembly extends around the outside of the lifejacket cover, a similar tubular bladder assembly could be arranged to extend around the inside of the cover as illustrated in Figures 12 and 13.

Figure 12 shows a portion of the lifejacket which has been cut through to illustrated the internal structure, and Figure 13 shows the bladder assembly in greater detail. In this arrangement, a bladder 34 is located inside a reinforcing plastic helix 35 which prevents the bladder being collapsed. A flexible plastic channel section 36 is located inside the bladder 34 to ensure that a fluid passageway is always maintained along the length of the bladder 34. The assembly of bladder 34, helix 35 and channel section 36 extends around the inside of the lifejacket cover 30 beside the main lifejacket bladder 33.

Claims

1. A buoyancy body which is intended to float in water in a predetermined attitude, comprising an inflatable enclosure, a source of gas under pressure, and means for releasing gas from the source into the enclosure to inflate the body, the gas releasing means comprising a chamber in which a mechanism is provided which releases gas from the source if water enters the chamber, an aperture being provided in a wall of the chamber such that water enters the chamber if the aperture is open and the chamber is immersed in water, a valve being provided to block the aperture unless the pressure outside the chamber exceeds the pressure inside the chamber to a predetermined extent, and the chamber being mounted on a portion of the body which when the body floats in the predetermined attitude is immersed in water, wherein the chamber communicates with an expansion enclosure which is outside the inflatable enclosure, which is exposed to the environment outside the inflatable enclosure, and which at least in part is located at a position remote from the chamber and above the chamber when the body floats in the predetermined attitude.

2. A buoyancy body according to claim 1, wherein the expansion enclosure is an inflatable bladder.

3. A buoyancy body according to claim 2, wherein the bladder is located in an open body.

4. A buoyancy body according to claim 3, wherein the open body is an open- ended tube.

5. A buoyancy body according to claim 2, 3 or 4, wherein a reinforcing body is provided within or around the bladder to resist flattening of the bladder.

6. A buoyancy body according to any one of claims 2 to 5, wherein the bladder is located at the said position remote from the chamber and is connected to the chamber by a connecting tube.

7. A buoyancy body according to claim 6, wherein the buoyancy body is a lifejacket having a flexible outer cover within which the inflatable enclosure is received, the bladder and connecting tube being located between the cover and the inflatable enclosure.

8. A buoyancy body according to any one of claims 2 to 5, wherein the bladder extends from adjacent the chamber to the said point remote from the chamber.

9. A buoyancy body according to claim 8, wherein the buoyancy body is a lifejacket having an outer cover within which the inflatable element is received, and the bladder is incorporated in beading secured to the cover of the lifejacket.

10. A buoyancy body according to claim 9, wherein the beading extends around the periphery of the outside of the lifejacket cover.

11. A buoyancy body according to any preceding claim, wherein a transparent window is provided in a wall of the chamber and a moisture-sensitive indicator is located behind the window within the chamber, the indicator changing colour if moisture penetrates the chamber.

12. A buoyancy body according to any preceding claim, comprising a cover for sealing the aperture to selectively prevent water entering the chamber.

13. A buoyancy body according to any preceding claim, wherein the gas source comprises a cylinder of pressurised gas and the gas releasing means comprises a plunger displaceable by a spring so as to drive a puncturing device into a seal in the gas source, a water sensitive member preventing displacement of the plunger unless water enters the chamber.

14. A buoyancy body according to claim 13, wherein the spring is a compression spring arranged around the plunger, the plunger being retained in position by a bobbin which is supported on the plunger and biased by the spring against a support, and the end of the plunger remote from the gas cylinder extending to a position outside the chamber to enable the position of the plunger to be visually checked.

15. A buoyancy body according to any preceding claim, wherein the valve comprises a spring-loaded diaphragm valve.

16. A buoyancy body substantially as hereinbefore described with reference to Figures 3 to 6, Figure 7, Figure 8, or Figures 9, 10 and 11 of the accompanying drawings.