GB2188009A

GB2188009A - Inflatable lifejacket

Info

Publication number: GB2188009A
Application number: GB08705169A
Authority: GB
Inventors: Kenneth Charles Lucas; Iain Logan
Original assignee: RFD Ltd
Current assignee: RFD Ltd
Priority date: 1986-03-07
Filing date: 1987-03-05
Publication date: 1987-09-23
Also published as: FR2595315A1; US4753621A; GB8705169D0; GB8605655D0; GB2188009B

Description

GB2188009A 1 SPECIFICATION slip over a wearer's head upon a jump de scent

into water.

Inflatable lifejacket According to a first aspect of the present invention, there is provided an inflatable life The present invention relates to an inflatable 70 jacket for providing buoyancy in water to a lifejacket which provides buoyancy in water to wearer of the lifejacket comprising an inflata a wearer of the lifejacket and which comprises ble buoyancy envelope which is donned by a an inflatable buoyancy envelope which is wearer who passes his head through a neck donned by the wearer who passes his head opening in the envelope to bring a main body through a neck opening in the envelope to 75 portion of the envelope to overlie the chest bring a main body portion of the envelope to with a neck portion of the envelope passing overlie the chest with a neck portion of the round the sides and back of the neck and envelope passing round the sides and back of resting on the shoulders, characterised in that the neck and resting on the shoulders. the neck portion of the envelope is formed by In inflatable lifejackets hitherto proposed a 80 two inflatable neck sections extending up- neck portion is provided which extends up- wardly from the main body portion at each wardly from the main body portion on one side thereof and at their upper ends being side of the lifejacket, passes round the back connected together in the region of the back of the neck of the wearer and extends down- of the neck of the wearer by connecting wardly to the other side of the main body 85 means which holds the upper ends together in portion. The neck portion together with the a manner which permits spacing of them upper edge of the main body portion defines when the envelope is uninflated to provide a a neck opening which is of a fixed circumfer- neck opening through which the wearer can ential length and which is of a size to permit pass his head but which so constrains the the wearer of the lifejacket to pass his head 90 two ends when the envelope is inflated as to through it. While providing an opening of su- define a neck opening which obstructs pas fficient circumferential length for passage of sage of the wearer's head.

the head, the neck portion must additionally The connecting means may comprise one or ensure a secure fit around the neck of the more constraining straps, the strap or each of wearer upon inflation. It is considered desir- 95 the straps extending from a point on one of able and sometimes it is a requirement to en- the neck sections to a point on the other of sure a fit around the neck which will prevent the neck sections in the regions of the upper the neck portion of the lifejacket from slipping ends thereof and preferably the strap or one over the head under specific test conditions, or each of the straps is arranged to extend in in which for example the wearer is required to 100 a path over an inflatable portion of one or make a ten foot jump into water with the other or of each of the neck sections.

lifejacket inflated. While inflation of the neck In an embodiment of the invention herein portion of the conventional lifejacket does give after to be described two constraining straps a rigidity to the neck opening sufficient to of- are provided, one of which extends from the fer resistance to displacement of the neck 105 inner edge of a first of the two neck sections portion during a jump descent into the water, to the outer edge of a second of the neck displacement can occur and efforts have been sections in a path across an inflatable portion made to reduce the risk of displacement by of that neck section and along the front of the modification of the lifejacket in the region of envelope, and the other of which extends the neck opening. 110 from the inner edge of the second of the two In prior British Patent Specification No. neck sections to the outer edge of the first of

1601947, spaced fabric straps are provided the two neck sections in a path across an which extend vertically over the neck opening inflatable portion of that neck section and from the upper edge of the inflatable neck along the rear of the envelope.

portion down to the upper edge of the inflata- 115 Preferably, the constraining straps are such ble main body portion. In an uninflated condi- as to hold the upper ends of the neck sec tion, the lifejacket is donned by the wearer tions in overlapping relationship when the en pushing his head through the neck opening velope is inflated. In addition, a further con and also through the opening between the straining strap may be connected between the fabric straps, the straps being readily distwo inner edges of the neck sections in the placed with the lifejacket in the uninflated con- regions of the upper ends thereof to prevent dition. The wearer then inflates the lifejacket. displacement of the two neck sections beyond When the neck portion inflates it tensions the predetermined limits.

fabric straps which then serve to prevent the To reduce manufacturing costs, it is now wearer's head from slipping back through the 125 common practice to construct a buoyancy en neck opening. velope from two sheets of a plastics material It is an object of the present invention to which overlie each other and which are seam provide an inflatable lifejacket of an alternative welded together to form the envelope outer form which reduces substantially the risk that edge and the neck opening edge. It has how the neck portion of the inflated lifejacket will 130 ever long been recognised that stresses set 2 GB2188009A 2 up at the joined edges of the material place with the envelope uninflated and lying flat and limitations on the ultimate burst pressure undisplaced, which can be sustained by the lifejacket. A Fig. 2 is a schematic front elevation of part burst pressure of 10 p.s.i. minimum is de- of the uninflated buoyancy envelope shown in manded, for example, to ensure that the life- 70 Fig. 1, displaced to facilitate donning of the jacket does not burst should it first be orally lifejacket by passage of the wearer's head inflated and then subsequently additionally infl- through an enlarged neck opening, and ated by an accidental discharge of the pres- Fig. 3 is a schematic end view of the buoy surised gas cylinder of the inflation unit used ancy envelope shown in Fig. 1 with the buoy- for automatic inflation. It can be shown that 75 ancy envelope inflated.

the stress in the material at a join, for Referring first to Fig. 1, a buoyancy envel example at the join provided at the neck ope 11 is formed by two impermeable sheets opening of the lifejacket, is proportional to the 12 and 13 of a plastic coated material which product of the internal pressure of the envel- overlie each other and which are joined to ope and the radius of curvature of the material 80 gether along their edges by welding in a sin at the join. In prior British Specification No. gle hit operation to form an envelope edge 14

1601947 an attempt has been made to allevi- having the continuous contour shown in Fig.

ate the problem at the neck opening by pro- 1. As will be seen, the envelope 11 com viding in the region of the front of the neck a prises an inflatable main body portion 15 and longer horizontal neck seam, which reduces 85 a neck portion 16 formed by two inflatable the. resultant hoop stress. neck sections 17 and 18 which overlap each It is an object of the present invention to other as shown and which are connected to provide in an inflatable lifejacket alternative or gether by two constraining straps 19 and 20.

additional means whereby the hoop stresses As will be seen, the constraining strap 20 at the joins at the front of the neck opening 90 extends from the inner edge of the neck sec are reduced. tion 17 to the outer edge of the neck section According to a second aspect of the pre- 18 while the constraining strap 19 extends sent invention there is provided an inflatable from the inner edge of the neck section 18 to lifejacket for providing buoyancy in water to a the outer edge of the neck section 17. The wearer of the lifejacket comprising an inflata- 95 neck sections 17 and 18 in their overlapping ble buoyancy envelope which is donned by a disposition as shown in Fig. 1 define a neck wearer who passes his head through a neck opening 21, which is bounded by an inner opening in the envelope to bring a main body edge 22 of the neck section 17, an inner portion of the envelope to overlie the chest edge 23 of the neck section 18 and an upper with a neck portion of the envelope passing 100 edge 24 of the main body portion 15 of the round the sides and back of the neck and envelope.

resting on the shoulders and with an upper Although the neck opening 21 shown in Fig.

edge of the main body portion of the envel- 1 is of small dimension, it can be enlarged ope defining a lower part of the neck opening, substantially when the envelope is in the uni- chnracterised in that the main body portion of 105 nflated condition by displacing the two neck the envelope is constrained in a region be- sections 17 and 18 from their overlapping dis tween the upper edge of the main body por- position as shown in Fig. 1 to a spaced dis tion and its lower edge to reduce the radius position as diagrammatically illustrated in Fig.

of curvature of the envelope at the upper 2. The disposition of the sections 17 and 18 edge of the main body portion when the en- 110 in Fig. 2 as well as the disposition of the two velope is inflated. constraining straps 19 and 20 is shown in In an embodiment of the invention according simplified form for the purpose of illustration to its second aspect the upper edge of the and it should be recognised that the configura main body portion of the envelope defining tion would vary from that shown depending the lower part of the neck opening extends 115 upon the way in which the fifejacket is donned generally in a straight line across the lifejacket by a wearer. If the wearer first uses his hands and the envelope is constrained along a line to enlarge the neck opening 21 without apply parallel thereto. Furthermore, where the envel- ing considerable outward loading on the two ope is formed by sheets of a flexible material sections 17 and 18, the neck sections 17 and which overlie each other and which are seam 120 18 would take up dispositions approximating welded together to form the envelope edge, that shown in the simplified form in Fig. 2.

the envelope sheets are joined together in an Where however the wearer simply pushes his intermediate region of the main body portion head through the neck opening 21, a configu of the envelope also by welding. ration intermediate between that shown in Fig.

One embodiment of the invention will now 125 1 and that shown in Fig. 2 would develop be described by way of example with refer- depending upon the size of opening required ence to the accompanying drawings in which: for passage of the wearer's head. Clearly, the Fig. 1 is a schematic front elevation of a neck opening 21 as shown in Fig. 1 is sub buoyancy envelope of a lifejacket according to stantially enlarged by moving the overlapping the first and second aspects of the invention, 130neck sections 17 and 18 from their overlap- 3 GB2188009A 3 ping disposition to the spaced disposition The buoyancy envelope 11 illustrated in the shown in Fig. 2. Once the uninflated lifejacket drawings includes a pressurised gas inflation has been donned, the two neck sections 17 unit 27 including a conventional pressurised and 18 come to rest on the shoulders of the gas cylinder (not shown) which can be oper wearer and the two ends which extend around 70 ated to inflate the envelope by pulling on a the back of the neck of the wearer return to release tab 28, a topping-up tube 29 for oral their overlapping disposition as shown in Fig. topping-up of the envelope and conventional 1. Upon inflation of the envelope 11, the upwaist straps (not shown) for tying round the per ends of the two neck sections 17 and 18 wearer's waist to hold the main body portion are held in their overlapping disposition by the 75 of the envelope against the wearer's chest.

two straps 19 and 20 as best seen in Fig. 3. The envelope 11 would furthermore be pro Referring to Fig. 3, while it will be apparent vided with accessories (not shown), such as a that the two straps 19 and 20 prevent the lamp mounted at the edge of the envelope neck sections 17 and 18 from moving apart in and supplied from a battery also secured to a plane parallel to the principal plane of the 80 the edge of the envelope and a whistle remo envelope, the two neck sections 17 and 18 vably secured also at the edge and addition would in the absence of further constraint ally held captive by a cord. It is common have a freedom to move over each other. To practice for a lifejacket to be so constructed impose a limitation on such movement a fur- as to be reversible, that is to say, that it can ther constraining strap 25 is provided, which 85 be donned by a wearer so as to overlie the extends from the inner edge 22 of the neck chest either way round and in this event all section 17 to the inner edge 23 of the neck the facilities on it would be arranged to be section 18. equally accessible with the envelope either It will be apparent that the donned buoy- way round and duplicated where necessary to ancy envelope 11 when inflated provides a 90 achieve this end.

neck opening which can be substantially smal- In the embodiment of the invention herein ler than the opening required for passage of before described a single inflatable envelope is the wearer's head. Furthermore, when the life- provided by welding together two sheets 12 jacket is donned and inflated the wearer's and 13 of a plastics material. It is however neck is enclosed entirely by inflatable portions 95 sometimes necessary to meet a requirement of the envelope 11 which provide good cush- by an authority to provide a dual buoyancy ioning support for the head and offer con- chamber lifejacket in which two buoyancy en siderable resistance to displacement of the velopes are formed each with its separate infl neck portion of the envelope when a wearer ation unit. To provide the further envelope a is required to jump into the water from a con- 100 third sheet of a plastics material is employed siderable height of say ten feet above the which overlies the other two sheets and the water. three sheets are seam welded together in a With some lifejackets, a backstrap is prosingle hit operation to produce the two inflata vided to hold the neck portion of the lifejacket ble envelopes.

in place on the wearer's shoulders, but the 105

Claims

neck sections for such a lifejacket can never- CLAIMS theless be provided

in accordance with the 1. An inflatable lifejacket for providing buoy invention to give added security. ancy in water to a wearer of the lifejacket The buoyancy envelope 11 as shown in Fig. comprising an inflatable buoyancy envelope 1 is constructed from sheets 12 and 13 of a 110 which is donned by a wearer who passes his plastics material which overlie each other and head through a neck opening in the envelope which are seam welded to form the envelope to bring a main body portion of the envelope outer edge 14, the inner edges 22 and 23 of to overlie the chest with a neck portion of the the two neck sections 17 and 18 and the envelope passing round the sides and back of upper edge 24 of the main body portion 15. 115 the neck and resting on the shoulders, charac To reduce the stress imposed upon the edge terised in that the neck portion of the envel 24 which partly defines the neck opening 21, ope is formed by two inflatable neck sections the two envelope sheets 12 and 13 are seam extending upwardly from the main body por welded together in an intermediate region of tion at each side thereof and at their upper the main body portion 15 along a welding line 120 ends being connected together in the region 26, which has the effect of reducing the ra- of the back of the neck of the wearer by dius of curvature of the sheets 12 and 13 at connecting means which holds the upper ends the join along the upper edge 24. With the together in a manner which permits spacing of aim of reducing the stress placed upon the them when the envelope is uninflated to pro join along the upper edge 24 at the neck 125 vide a neck opening through which the wearer opening 21, the edge 24 is furthermore ar- can pass his head but which so constrains the ranged to be substantially straight throughout two ends when the envelope is inflated as to most of its length and to achieve optimum define a neck opening which obstructs pas reduction in stress along this edge the weld- sage of the wearer's head.

ing line 26 extends in a direction parallel to it. 130
2. A lifejacket according to claim 1, wherein 4 GB2188009A 4 the connecting means comprises one or more envelope passing round the sides and back of constraining straps, the strap or each of the the neck and resting on the shoulders and straps extending from a point on one of the with an upper edge of the main body portion neck sections to a point on the other of the of the envelope defining a lower part of the neck sections in the regions of the upper ends 70 neck opening, characterised in that the main thereof. body portion of the envelope is constrained in
3. A lifejacket according to claim 2, wherein a region between the upper edge of the main the strap or one or each of the straps is body portion and its lower edge to reduce the arranged to extend in a path over an inflatable radius of curvature of the envelope at the up- portion of one or other or of each of the neck 75 per edge of the main body portion when the sections. envelope is inflated.
4. A lifejacket according to claim 3, wherein 11. A lifejacket according to claim 10, two constraining straps are provided, one of wherein the upper edge of the main body por which extends from the inner edge of a first tion of the envelope extends generally in a of the two neck sections to the outer edge of 80 straight line across the lifejacket and wherein a second of the neck sections in a path the envelope is constrained along a line paral across an inflatable portion of that neck sec- lel thereto.

tion and along the front of the envelope, and 12. A lifejacket according to claim 10 or the other of which extends from the inner 11, wherein the envelope is formed by first edge of the second of the two neck sections 85 and second sheet portions of a flexible ma to the outer edge of the first of the two neck terial which overlie each other and which are sections in a path across an inflatable portion seam welded together to form the envelope of that neck section and along the rear of the edge and wherein the envelope sheet portions envelope. are joined together in an intermediate region
5. A lifejacket according to claim 4, wherein 90 of the main body portion of the envelope also the constraining straps are such as to hold the by welding.

upper ends of the neck sections in overlap- 13. A lifejacket substantially as hereinbefore ping relationship when the envelope is inflated. described with reference to the accompanying
6. A lifejacket according to claim 5, wherein drawings.

a further constraining strap is connected be- Printed for Her Majesty's Stationery Office tween the two inner edges of the neck sec- by Burgess & Son (Abingdon) Ltd, Dd 8991685, 1987.

tions in the regions of the upper ends thereof Published at The Patent Office, 25 Southampton Buildings, to prevent displacement of the two neck sec- London, WC2A 'I AY, from which copies may be obtained.

tions beyond predetermined limits.
7. A lifejacket according to any of claims 1 to 6, wherein an upper edge of the main body portion of the envelope defines a lower part of the neck opening and wherein the main body portion of the envelope is constrained in a region between the upper edge of the main body portion and its lower edge to reduce the radius of curvature of the envelope at the upper edge of the main body portion when the envelope is inflated.
8. A lifejacket according to claim 7, wherein the upper edge of the main body portion extends generally in a straight line across the lifejacket and wherein the envelope is constrained along a line parallel thereto.
9. A lifejacket according to claim 7 or 8, wherein the envelope is formed by first and second sheet portions of a flexible material which overlie each other and which are seam welded together to form the envelope edge and wherein the envelope sheet portions are joined together in an intermediate region of the main body portion of the envelope also by welding.
10. An inflatable lifejacket for providing bu- oyancy in water to a wearer of the lifejacket comprising an inflatable buoyancy envelope which is donned by a wearer who passes his head through a neck opening in the envelope to bring a main body portion of the envelope to overlie the chest with a neck portion of the