US20040154067A1 - Device - Google Patents

Abstract

A cover for an immersion suit with a valve and an immersion suit having a valve and a cover are disclosed. In use, the cover is placed over an air expulsion valve of an immersion suit and is adapted to deform under action of an external force, such as water moving over the cover, in order to protect the valve from the external force. The cover is preferably adapted to deform and protect the valve in any direction regardless of the direction of the external force. The sensitivity of the valve can be increased to allow the efficient expulsion of air trapped within the immersion suit.

Description

RELATED APPLICATION
• This application is related to and claims priority from United Kingdom Application No.[0001]0219243.3, filed Aug. 17, 2002.
FIELD OF THE INVENTION
• This invention relates to a valve cover device for immersion dry suits, and more particularly, but not exclusively, relates to a valve cover for escape survival suits worn by aircraft occupants, both fixed wing and helicopter.[0002]
BACKGROUND OF THE INVENTION
• Immersion dry suits are employed as an aid to survival for aircraft occupants in the event of an aircraft ditching at sea. Such immersion suits are generally waterproof (often breathable) coveralls, with attached feet, waterproof entry zipper, and rubber seals at the neck and wrist. The immersion suit may be worn constantly or put on only in the event of an emergency. An immersion suit may provide some inherent insulation or may only provide a watertight barrier protecting the insulation of the clothing worn underneath.[0003]
• On ditching, an aircraft occupant may be immersed in water and may also become inverted if the aircraft, particularly a helicopter, capsizes. In this event the aircraft occupant must overcome the effects of immersion and disorientation to exit the aircraft and survive.[0004]
• The effects of sudden immersion in cold water are profound and significantly reduce the ability to hold one's breath. The wearing of an immersion dry suit by an escapee can significantly reduce the effects of this initial cold shock. However, the wearing of any immersion dry suit introduces the risk of additional buoyancy, as air is trapped within the immersion coverall. This is a particular problem for one-size-fits-all suits as they are big enough to be worn dry suit introduces the risk of additional buoyancy, as air is trapped within the immersion coverall. This is a particular problem for one-size-fits-all suits as they are big enough to be worn by large people, which results in air trapped within the suit particularly when they are worn by small people. This buoyancy can prevent a successful escape from an immersed cabin with fatal consequences. Moreover, should the escapee become inverted in the water, trapped air may move to the leg or foot portions of the suit and it may not be possible for the escapee to right him/her-self due to the additional buoyancy in the legs.[0005]
• The amount of additional buoyancy can be reduced by two methods of venting the immersion dry suit: either manual or automatic venting. The manual technique relies on the user employing a technique whereby they break and hold the neck seal of the immersion coverall open and away from the neck, squat down, and maintain this position whilst the air is vented through the neck seal, then close the neck seal before standing up. However, if the immersion coverall is ill fitting or the immersion coverall is put on quickly in an emergency abandonment situation and manual-venting method is not performed, then the problem of excess buoyancy may still persist.[0006]
• This problem can be overcome by automatic venting by means of air exhaust valves incorporated in the immersion dry suit. These valves are designed to provide a means of venting the excess air when the dry suit is immersed. These valves can be located on both the shoulders and lower leg regions of the immersion suits. Should the user enter the water feet first, the hydrostatic pressure will normally cause the air to move up the suit and vent from the shoulder valves; conversely, should the escapee enter the water head first the air will normally move down the suit and vent through the valves in the lower leg regions.[0007]
• The design of the air exhaust valves is commonly of a one-way design and features a rubber diaphragm that deforms on exposure to elevated internal air pressure. This elevated air pressure is the result of the hydrostatic pressure imparted by the water immersion forcing the trapped air into a reduced suit volume. The valves need to be very sensitive because the pressure differential in shallow water is small. In theory, the diaphragm seals are closed when exposed to an elevated external pressure and should remain watertight.[0008]
• However in practice, when such valves are exposed to water during escape from an aircraft, valve leakage can be experienced, particularly when the valves are located at the lower leg or ankle region of the immersion suit due, in part, to the escapee kicking in the water.[0009]
• Such dynamic forces experienced during an emergency ditching and escape can cause the sensitive sealing diaphragm to flutter and break its seal, usually by the shearing effect of water passing across the face of the air-exhaust valve, causing some water ingress.[0010]
• One potential corrective action could be to stiffen the diaphragm to resist exposure to such forces, but this action would have the effect of raising the valve's minimum operating pressure and reducing the valve's sensitivity. The result would be that the valve could only operate at higher internal pressures with the effect of leaving an amount of residual air within the immersion suit that would compromise underwater escape.[0011]
SUMMARY OF THE INVENTION
• According to the present invention there is provided a cover for a valve of an immersion suit, the cover being adapted to deform from a first shape to a second shape on action of an external force, wherein when the cover adopts the second shape it substantially protects at least a portion of the valve from the external force.[0012]
• Preferably, the cover comprises a base end and a head end connected to each other by at least one connecting portion. Preferably, the cover has a substantially tubular shape. Preferably, the base end is secured to the suit over or about the valve so that the valve is in fluid communication with a bore of the tubular cover.[0013]
• Preferably, the connecting portion(s) extend away from the suit.[0014]
• Preferably, the diameter of the base is greater than the diameter of the head. Preferably the tubular shape tapers inwardly as the tube extends from the base end to the head end, and more preferably, the cover is frusto-conical in shape.[0015]
• Typically, the connecting portion(s) resist flow of fluid therethrough whereas the head end and base end substantially allow the flow of fluids therethrough. Nevertheless, the head may include a means to reduce the likelihood of snagging, such as a porous mesh screen.[0016]
• Preferably the head end has a circular section edge. Typically the porous mesh screen is attached to the circular section edge. Preferably, the base end is of a hexagonal shape. Therefore, the cross section of the cover typically evolves from a hexagonal cross section at the base end, to a circular cross section at the head end.[0017]
• Typically the valve is a diaphragm one-way air exhaust valve comprising at least one exhaust.[0018]
• Preferably each/the connecting portion of the cover extend to a length greater than or equal to the distance between a point where each/the connecting portion is secured to the suit and the furthest exhaust from that point. Therefore when the cover deforms and adopts the second shape, the connecting portions are preferably large enough to substantially protect the exhaust(s).[0019]
• Preferably, when the cover adopts the second shape, some air can escape through the exhausts.[0020]
• The external force may be a dynamic force typically generated by fluid such as water moving with a shearing action with respect to the valve.[0021]
• Preferably, the cover can deform from a first shape to a second shape on action of an external force from any direction.[0022]
• Preferably, the cover is made from a plurality of conjoined segments. More preferably, there are three segments.[0023]
• Preferably, the three segments are stitched together to form the conical cover. More preferably the three segments are sealed together using machine-applied hot-melt adhesive tape.[0024]
BRIEF DESCRIPTION OF THE FIGURES
• An embodiment of the present invention will now be described by way of example only, in which:[0025]
• FIG. 1 is a front view of a waterproof immersion suit;[0026]
• FIG. 2 is a back view of the waterproof immersion suit showing a valve cover in accordance with the present invention;[0027]
• FIG. 3[0028]ais a bottom view of a diaphragm one-way air exhaust valve;
• FIG. 3[0029]bis a side view of the diaphragm one-way air exhaust valve;
• FIG. 3[0030]cis a top view of the diaphragm one-way air exhaust valve;
• FIG. 4 is a plan view of the valve cover shown in FIG. 2;[0031]
• FIG. 5 is a sectional side view of the valve cover of FIG. 2 and the valve;[0032]
• FIG. 6 is an enlarged sectional view of circle B of FIG. 5 detailing attachment of a mesh screen to the valve cover of FIG. 2;[0033]
• FIG. 7 is a side view of a flat pattern segment used to form the valve cover of FIG. 2.[0034]
DETAILED DESCRIPTION OF THE INVENTION
• A waterproof immersion dry suit or garment is shown in FIG. 1 and comprises a one-[0035]piece suit50 with attachedwaterproof socks51. Thesuit50 comprises a waterproofmain entry zip1,neck2 andwrist3 watertight seals and two shoulder diaphragm one-wayair exhaust valves4. Thezip1 extends diagonally down the front of thesuit50 from the right shoulder to left hip.
• The[0036]suit50 is typically made from a waterproof, breathable fabric such as Gortex™, or alternatively from any of a range of waterproof non-breathable fabrics. Thesuit50 comprises a number of flat pattern pieces assembled using techniques appropriate to the material. This could be by adhesive only, or by the use of stitching and then the use of hot melt adhesive seam sealing tape. Theseals2,3 are typically made from latex or neoprene.
• A back view of the[0037]suit50 is shown in FIG. 2. Valves6 (not shown in FIG. 1) are provided on an outside ankle position61 (as worn) of thesuit50. Thevalves6 are typically diaphragm one-way air exhaust valves although any suitably sensitive one-way air valve may be used. Thevalves6 are covered by avalve cover5 in accordance with the present invention to protect them from the shearing effects encountered when immersed in water.
• Referring now to FIG. 4, the[0038]valve cover5 comprises threesegments31,32,33 which are constructed externally and about any existing, commercially available, one way air exhaust valve such as thevalve6; one example of such avalve6 is made by Multifabs Survival Limited of Dyce, United Kingdom, under the product number MSL COMO 50(A) (casing) and MSL COMO 13A (diaphragm).
• A[0039]segment31 is shown in flat pattern in FIG. 7, thesegments32 and33 are identical to thesegment31 and all are made from any lightweight waterproof fabric. Thesegment31 has twobottom edges34,35 which are at an angle of 35-45° to each other, twoside edges36,37 extending from the outer ends of thebottom edges34,35, and atop edge38.
• The side edges[0040]36,37 are first stitched then top stitched to side edges37,36 of theother segments32,33 along seam lines H-G and D-E to form a seam. The side edges36,37 of thesegments32,33 are similarly stitched together to form a substantiallyconical body25 with ahexagonal base26. Each seam H-G, D-E is then sealed on the inner face of each segment31-33 using machine-applied hot-melt adhesiveseam sealing tape19.
• Top ends[0041]39,40 of side edges36,37 are shaped to form acylindrical portion16 at the top of thebody25 when the segments31-33 are joined together. Thetop edges38 of the conjoined segments31-33 are then turned down and stitched closed at22 to form afinished rim27, as shown in FIG. 6. Amesh screen8 is stitched18 along therim27 to minimise the potential for the edge of thecylindrical rim27 to snag during an escape. The length of thecylindrical portion16 is preferably 5 mm.
• The bottom edges[0042]34,35 of the conjoined segments31-33/body25 are turned under to size and stitched. Thebody25 is then presented to thesuit50, centred around thevalve6, and secured to thesuit50 by stitching11. The bottom edges34,35 are then sealed with machine-appliedseam sealing tape13, as shown in FIG. 5.
• In one embodiment of the[0043]valve cover5, thebottom edges34,35 are each 70 mm in length and form ahexagonal base26 of diameter 120 mm. The diameter of thehexagonal base26 is such that it provides sufficient clearance for the machine-appliedseam sealing tape13 application without thevalve6 interfering therewith.
• In one embodiment the diameter[0044]21 of thecylindrical portion16 is 30 mm. Themain body25 of thecover5 extends from thehexagonal base26 to form a substantially conical shape over thevalve6.
• The diameter[0045]21 of the cylindrical portion is such that the surface area of holes in themesh screen8 allow at least an equivalent amount of air to pass therethrough compared with the amount of air which can be vented throughair vents15 of thevalve6. This ensures thevalve cover5 does not become inflated itself resulting in unwanted buoyancy.
• The height of the[0046]cylindrical portion16 is optimum such there is sufficient material to form an effective mating surface with the edge of themesh screen8 to facilitate stitching, yet maintain a low profile, again to minimise the potential for snagging.
• FIGS. 3[0047]a-3cillustrate a typical and conventional diaphragm one-wayair exhaust valve6 configuration, comprising an inner housing45 andouter housing46 into which a flat mushroom rubber diaphragm (not shown) is housed. Air outlet vents15 are provided in the inner45 and outer46 housing to allow the escape of air from within thesuit50.
• To manufacture the[0048]suit50 with thevalves6, a circular aperture (not shown) of a diameter slightly less than that of the inner45 and outer46 housing is cut in thesuit50. The inner45 and outer46 housings with the diaphragm therebetween are held either side of the aperture so that they are concentric with each other and the aperture. Their edges are then plastic welded together and being of a greater diameter than the aperture, also hold a portion of thesuit50 therebetween.
• The height of[0049]face14 of the segments31-33 is substantially equal to the height offace17. The height of thesefaces14,17 is also substantially equal to the distance between any point on thestitching11 and thefurthest air vent15 on thevalve6 from that point. For one embodiment, the height of thefaces14,17 is 80 mm which is substantially equal to the distance between any point on thestitching11 and thefurthest air vent15 from that point on thestitching11.
• Thus, in the event of a person wearing the[0050]immersion suit50 entering water, the air pressure within thesuit50 will exceed the pressure outside thesuit50 and the diaphragm of thevalve6 will deform and allow the air to escape through the air vents15 from within thesuit50 to outside thesuit50 thereby reducing the amount of trapped air within thesuit50 and the unwanted buoyancy in thesuit50. Should for any reason, the pressure be greater outside thesuit50, the diaphragm will not deform and no fluid will travel through thevalve6. Air may also escape through the shoulder valves104.
• The person moving their legs in the water will cause fluid to move across the[0051]valve cover5, i.e. an external, dynamic force is applied to thecover5. Thecover5 will deform under action of the dynamic force and cover and protect the air vents15 of thevalve6 from the force. For example, if a dynamic force occurs in the direction ofarrow28 shown in FIG. 5, theface17 of thecover5 will deform and its upper end17uwill follow the path ofbroken line29. Theface17 will thereby cover and protect the air vents15.
• Certain embodiments of the invention benefit from the[0052]vents15 being protected in this way, without being completely sealed. Typically, a second dynamic force from another angle will quickly ensue due to the user moving their legs in a different direction and thecover5 will deform at the angle of the second dynamic force again protecting the air vents15 from the water rushing past thevalve6. Certain embodiments of the invention benefit from the fact that thecover5 can deform at any angle in response to a dynamic force in order to protect the air vents15 regardless of the angle of exposure to dynamic forces.
• The[0053]covers5 may also be positioned over the shoulder valves104. However, thecovers5 are more useful over valves on theankle portions61 due to the additional shearing these valves are exposed to when the person kicks his/her legs or swims while immersed. Other dynamic forces may also be exposed to thevalve cover5, for example, in the event of an underwater capsize wherein a flooded cabin (not shown) rotates underwater.
• Certain embodiments of the invention allow the diaphragm to be set at a more sensitive level so that the maximum amount of air within the[0054]suit50 may be expelled.
• Certain embodiments of the invention protect the[0055]valve6 without blocking the air vents15, in contrast to a flat cover over thevalve6. Moreover, certain embodiments of the invention benefit from being flexible in contrast to a flat patch cover which may follow the curved profile of a user's leg and prevent thevalve6 from working.
• The segments[0056]31-33 can vary in shape so that thebase26 of thecover5 is circular or polygonal. The more edges thebase26 has the more likely it is to deform accurately in response to a dynamic force. On the other hand, the more edges thebase26 has the more difficult it is to be stitched to thesuit50 and so ahexagonal base26 is considered an optimum compromise.
• Certain embodiments of the invention improve the performance of such a one-way[0057]air expulsion valve6 such that it retains the sensitivity of a flexible diaphragm seal whilst eliminating the potential for water ingress when exposed to the dynamic forces associated with an underwater escape.
• Other improvements and modifications may be incorporated without departing from the scope of the invention.[0058]

Claims (23)

We claim:

1. A cover for a valve of an immersion suit, the cover being adapted to deform from a first shape to a second shape on action of an external force, wherein, in use, when the cover adopts the second shape it substantially protects at least a portion of the valve from the external force.

2. A cover as claimed inclaim 1, comprising a base end and a head end connected to each other by at least one connecting portion.

3. A cover as claimed inclaim 2, wherein the at least one connecting portion resists flow of fluid therethrough whereas the head end and the base end substantially allow the flow of fluids therethrough.

4. A cover as claimed inclaim 1, wherein the cover is adapted to deform from the first shape to the second shape on action of the external force from substantially any direction.

5. A cover as claimed inclaim 1, the cover having a substantially tubular shape.

6. A cover as claimed inclaim 2, wherein the diameter of the base is greater than the diameter of the head.

7. A cover as claimed inclaim 5, wherein the tubular shape tapers inwardly the base end to the head end.

8. A cover as claimed inclaim 7, wherein the cover is frusto-conical in shape.

9. A cover as claimed inclaim 2, wherein the base end is polygonal.

10. A cover as claimed inclaim 2, wherein the head end is substantially circular.

11. A cover as claimed inclaim 2, wherein the connecting portion transforms from a polygonal cross section at the base end, to a circular cross section at the head end.

12. A cover as claimed inclaim 2, wherein the head end includes a mechanism to reduce the likelihood of snagging.

13. A cover as claimed inclaim 12, wherein the mechanism comprises a mesh screen.

14. A cover as claimed inclaim 1, wherein the cover is formed from a plurality of conjoined segments.

15. An immersion suit comprising at least one valve, and at least one cover as claimed inclaim 1.

16. An immersion suit comprising at least one valve, and at least one cover as claimed inclaim 2.

17. An immersion suit as claimed inclaim 16, wherein the at least one connecting portion extends away from the immersion suit.

18. An immersion suit as claimed inclaim 16, wherein the base end is secured to the immersion suit in the vicinity of the valve, such that the valve is in fluid communication with a bore of the cover.

19. An immersion suit as claimed inclaim 16, wherein the at least one valve comprises at least one air exhaust and when the cover adopts the second shape, the at least one connecting portion is of sufficient surface area to substantially protect the at least one air exhaust.

20. An immersion suit as claimed inclaim 19, wherein the at least one connecting portion extends to a length at least equal to the distance between any one point where the said connecting portion is secured to the immersion suit and the furthest air exhaust from that one point.

21. An immersion suit as claimed inclaim 15, wherein the valve is a one-way air exhaust valve.

22. An immersion suit as claimed inclaim 19, wherein when the cover adopts the second shape, air is permitted to escape from within the immersion suit through the at least one valve exhaust.

23. An immersion suit as claimed inclaim 15, wherein the external force is caused by fluid moving with a shearing action with respect to the valve.

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