Abstract:
A device which will act efficiently as a float for any article (e.g. keys, mobile telephone, wallet) attached thereto when dropped into water comprises an inflatable bag ( 14 ) of substantially waterproof and air impervious material, a container ( 12 ) of compressed gas, and trigger means ( 16,30,32 ) associated with the container ( 12 ) and operable upon immersion of the device in water to open the container ( 12 ) and allow gas from the container ( 14 ) to inflate the bag ( 14 ). The trigger means comprises a valve ( 16 ) mounted on the container ( 12 ) and connecting the container to the inflatable bag ( 14 ), retainer means ( 30 ) operative to hold the valve ( 16 ) in a closed condition, and water reactive means ( 32 ) which, upon contact with water, serves to release the retainer means ( 30 ) and allow the valve to open. The water reactive means may comprise a band of material ( 32 ), at least part of which is water reactive.

Description:
This application is a 371 of PCT/GB2007/000315 filed on Feb. 1, 2007. 
     This invention concerns a device which is attachable to other articles, such as keys, wallets and mobile telephones, but not limited thereto, and which incorporates an automatically inflatable bag which will serve as a float for such articles if they are dropped into water, accidentally or otherwise. In this way retrieval of such articles is facilitated. 
     BACKGROUND 
     Cork devices have for many years been attached to items such as keys to enable them to float and be retrievable if dropped into water, for example in harbours and marinas. These cork devices are relatively bulky and are not sufficiently buoyant to support heavy items. 
     More recently, various proposals have been made, for example in FR 2733482, US 2004/0137810 and GB 2406265 A, for devices for this purpose which incorporate an automatically inflatable bag to serve as the float. These devices are all impractical to produce economically, or else are unsafe or unreliable in operation. For example, FR 2733482 proposes a cylinder in which acetylene gas is generated by a chemical reaction upon contact of calcium carbide with water. Even if this reaction was reliably achieved, it is clearly unsafe for use as acetylene is flammable. The proposal in US 2004/0137810 involves breakdown in water of a barrier between two compartments within the inflatable balloon, which would be most unreliable in practice. The proposal in GB 2406265 A and other known devices involve use of a canister of compressed carbon dioxide and a trigger device which involves piercing of a seal to this canister, the trigger device being dependent on breakdown of a material on contact with water. These are expensive to produce because a canister of compressed carbon dioxide must be of metal and sufficiently robust to withstand the high pressure required to contain the gas. Moreover, they are unreliable in use in part because of frequent occurrence of air locks in the passage of water to the water degradable material, but also because the force required to pierce such a seal is considerable and may not be achieved. 
     OBJECT OF THE INVENTION 
     An object of the invention is to provide a device of this general type which is more cost-effective to produce, and far more reliable in use than any of the known or previously proposed devices. 
     BRIEF SUMMARY OF THE DISCLOSURE 
     According the invention, a flotation device is proposed which comprises an inflatable bag of substantially waterproof and air impervious material, a container of compressed gas, trigger means associated with the container and operable upon immersion of the device in water to open the container and allow gas from the container to inflate the bag, a casing in which the bag, the container and the trigger means are housed, and means for attachment of the device to another article, but characterised in that the trigger means of such a device comprises a valve mounted on the container and connecting the container to the inflatable bag, retainer means operative to hold said valve in a closed condition, and water reactive means which, upon contact with water, serves to release the retainer means and allow the valve to open. 
     The operation of such a valve which is released in this way is highly reliable. 
     The valve may be spring biased into an open condition in some embodiments, but in other embodiments it may be spring biased into a closed condition. Various arrangements are proposed for release of the retainer means which hold the valve against the spring bias into an open condition in the first mentioned embodiments, or conversely which counter the spring bias into the closed condition in the second mentioned embodiments. In the latter, the spring itself comprises the retainer means. 
     In any arrangement, however, the water reactive means is preferably provided in the form of at least one water reactive band (strip) of material. A starch based polymer is a suitable material for such a band. 
     Advantageously, the container may be of plastics material and the compressed gas may suitably be a hydrogenated chlorofluorocarbon compound. This gas requires compression at far lower pressures than carbon dioxide, and can safely and suitably be contained in a low cost container of plastics material similar to the housing of a conventional inexpensive cigarette lighter. Moreover, it is safe to use and not an environmental hazard. 
     In order to prevent any possibility of an air lock developing in the passage of water into the device once it has been immersed, the casing preferably has a plurality of sidewalls and a plurality of elongated apertures are formed in at least two of these sidewalls. Additionally or alternatively the casing is provided with at least two separate rows of elongated apertures, at least one row being provided above the position of the water reactive means therein, and at least one row being provided below the position of the water reactive means therein. 
     In a further development of either aspect of the invention, an illumination device is advantageously mounted inside the inflatable bag. Such illumination device suitably comprises a light emitting diode (LED) powered by at least one battery, the latter being automatically connected to the LED upon inflation of the bag. This can be achieved by having a strip of insulating material initially located between the battery or batteries and the LED, said strip also being connected to the neck of the bag so that it is automatically withdrawn from extending between the battery or batteries and the LED upon inflation of the bag. 
     A further inventive development is the manner of attachment of such an illumination device inside the inflatable bag. This is suitably achieved by providing a projection on the illumination device whereby it is attached inside the inflatable bag, preferably at a location remote from the neck of the bag, by a clip or O-ring fitted over said projection from outside the bag. A further possibility is to provide the aforesaid clip or O-ring with an additional, preferably expansible, loop to facilitate retrieval of the device upon flotation. 
     Other advantageous developments will be apparent from the following description of specific embodiments of the device of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described further, by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1  is a side view of a first practical embodiment of the device of the invention; 
         FIG. 2  is a front view of the same embodiment; 
         FIG. 3  is a top plan view of the same embodiment; 
         FIG. 4  is a cross-section along line B-B of  FIG. 2  of the same device; 
         FIG. 5  is a cross-section along line A-A of  FIG. 3  of the same device; 
         FIG. 6  is a cross-section along line C-C of  FIG. 2  of the same device; 
         FIG. 7  is an enlarged detail of a central region of the device as shown in  FIG. 5 ; 
         FIG. 8  is a reduced scale diagrammatic cross-section showing the device of  FIGS. 1 to 7  once the bag has inflated; 
         FIG. 9  is an enlarged detail of the casing region of the device in the inflated bag condition shown in  FIG. 8 ; 
         FIG. 10  is a view comparable to  FIG. 5 , but to a larger scale, of a second embodiment of the device of the invention; 
         FIG. 11  is a cross section, similar to  FIG. 10 , of a third embodiment of the device of the invention; 
         FIG. 12  is a cross section, similar to  FIG. 10 , of a fourth embodiment of the device of the invention; and 
         FIG. 13  is a cross section, similar to  FIG. 10 , of a fifth embodiment of the device of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring firstly to  FIGS. 1 to 7 , a practical embodiment of the flotation device of the invention comprises a substantially rectangular casing  10  of plastics material which houses a gas container  12  and an inflatable bag  14 , the container  12  being connected to the neck  15  of the bag  14  by way of a valve which is designated generally by reference numeral  16 . 
     The inflatable bag  14  is of a substantially waterproof, water impervious, highly flexible and strong material, such as polyurethane film of the type used for modern condoms. The gas container  12  is made of plastics material, typically acetyl plastics, and is of a similar size and shape to the fuel tank of an inexpensive cigarette lighter. The gas inside is a hydrogenated chlorofluorocarbon which may be under a pressure of about 40 psi. 
     The container  12  fits into a lower region of the casing  10  and the bag  14  is folded into a small volume in an upper region of the casing  10 . As best shown in  FIG. 7  the valve  16  comprises a cup shaped body  26  mounted in a top wall  13  of the container  12 . This body  26  defines a well, in the base of which a sealing plate  17  is mounted. It also has a side opening  18  communicating to the interior of the container  12 . A tubular valve member  19  which is axially displaceable is located in the well of the body  26  with a sealing ring  29  there between. This tubular member  19  provides a conduit between the interior of the gas container  12  and the interior of the inflatable bag  14  as the neck  15  of the bag  14  is connected to a ring  24  which fits below a wedge profiled flange  28  at the top of the member  19 . A helical spring  22  located around the tubular member  19  within the body  26  acts between the sealing plate  17  and a collar  27  on the tubular member to bias the tubular member  19  into a valve open condition where its bottom end is lifted from the sealing plate  17  (see  FIGS. 8 and 9 ). 
     However, retainer means in the form of a U-shaped spring  30  and a band  32  serve to hold the tubular member  19  in a valve closed condition, against the bias of the spring  22 , where the bottom end of the member  19  is pressed firmly against the sealing plate  17 . 
     The U-shaped spring  30 , as shown in  FIGS. 4 and 5 , extends around the base of the container  12 . The side walls and base of the container  12  are recessed to accommodate and locate the limbs and central section of the U-shaped spring  30 , as is evident in  FIGS. 4 and 5 . At its upper end the U-shaped spring  30  has opposing inwardly directed gripper arms  31  which fit behind a further intermediate flange or collar  25  on the tubular valve member  19  to hold it in its lower, closed condition as just explained. The U-shaped spring  30  is held under compression, against its natural tendency to spring open with the gripper arms  31  moving further apart, by the band  32  which encircles the container  12  and the respective limbs of the spring  30 . This band  32  is water reactive in that it will disintegrate or rupture when immersed in water for a few moments. It may be made wholly or partially from a material, such as a starch based polymer, which softens and/or dissolves when immersed in either saltwater or freshwater. Alternatively, it may be made from a strip of material, such as polyurethane, which is not reactive to water, but which has its ends fastened together by a material, such as calcium carbonate, which rapidly dissolves in either saltwater or freshwater. 
     Pairs of catch projections  23  extend upwards beyond the top wall  13  at each side of the container  12  to retain a plate  35 , which has a central aperture  36  through which the neck  15  of the bag  14  is inserted. This facilitates assembly during manufacture of the device and also facilitates reliable operation of the valve and inflation of the bag  14 . 
     A circular tab  37  formed with an aperture  39  is provided as an integral extension from the base of the gas container  12  and extends through a corresponding opening in the casing  10 . This enables attachment of the device by way of a key ring or similar articles, such as keys or purses or other items. Attachment of an article directly to the gas container  12  minimises any risk of its detachment from the deployed float once the device is immersed, as may be more likely to occur if its attachment is by way of the casing and the casing separates from the inflated bag and its connected gas supply container. 
     As shown in  FIGS. 1 and 2 , but also evident in  FIGS. 4 and 5 , the casing  10 , which is also made of any suitable plastics material, is provided with two rows of elongated apertures  38  in each of its sidewalls, one such row being arranged above the level of the band  32  and one such row being arranged just below the level of the band  32 . This ensures that upon immersion of the device in water, water quickly and reliably penetrates to the band  32  in order that it may be released as required, without the risk of air locks delaying water penetration, as has occurred in certain previous devices. 
     At the top, above the folded bag  14 , the casing  10  is closed by an end cap  40 . The end cap  40  has lugs  42  projecting from its inner surface adjacent each side edge, which lugs  42  are engageable as a snap fit into grooves  44  provided near the top of the corresponding opposing side walls of the casing  10 . This allows the end cap  40  to be reliably retained on the casing  10  in normal circumstances when the bag  14  is not being deployed as a float, yet also allows ready release of the end cap  40  upon inflation of the bag  14  at the time of immersion of the device. However, to ensure such ready release, an additional inner plate  46  is provided between the bag  14  and the end cap  40 . This inner plate  46  has a central projection  48  in the manner of the bead which fits into a corresponding central notch in the inner surface of the end cap  40 . When the bag  14  is beginning to inflate, pressure is transmitted from the bag  14  to the inner plate  46  and is then concentrated at the central location of the bead  48  as it is transmitted to the end cap  40 . This causes the end cap  40  to deform into a convex shape so that the respective lugs  42  at each side are simultaneously released and the end cap  40  as a whole along with the inner plate  46  quickly and reliably lifts off. 
     The manner of operation of the above described device will now be readily apparent. When the device is dropped into water, water penetrates the casing  10  via the numerous apertures  38  and the band  32  ruptures, thus releasing the U-shaped spring  30  so that its gripper arms  31  move apart, away from the flange  25  on the tubular valve member  19 . The tubular member  19  is therefore released and immediately urged upwards by the helical spring  22 , thus opening the valve  16  and allowing gas to pass from the container  12  into the bag  14  to inflate it. The end cap  40  is pushed off the casing  10  in the manner just described above. The device with fully deployed float as provided by the inflated bag  14  is shown in  FIG. 8 . 
     From a small device which may have a total volume of about 20 cubic centimeters, including a container  12  having a capacity of only about 10 to 15 cubic centimeters of gas, an inflated bag having a capacity of at least 1.5 liter (and usually 1.75 to 2 liters) can be obtained. Such an inflated bag is capable of buoyantly supporting an article weighing up to about 1 kg while also leaving sufficient of the balloon above the water surface so as easily to be seen. 
     The foregoing is illustrative and not limitative of the scope of the invention and many variations in detail are possible in other embodiments. 
     In one particular modified embodiment, which in other respects is the same as that just described, the U-shaped spring may be of a different type which is held under tension and thereby normally tends to have its gripper arms urged towards each other so as to engage behind the collar  25  and hold the valve  16  in its lower, closed condition. The band  32  is replaced by a different band or by a pad or more than one pad mounted inwardly of the limbs of the U-shaped spring, between the limbs and the container  12 , which band or pad(s) swell upon ingress of water to force the limbs and the gripper arms apart and release the valve  16  for inflation of the bag  14 . 
     In other embodiments alternative or additional means of attachment of an article to the device may be provided in the form of one or more pads of high grab adhesive material mounted on the casing  10 . In this way, multiples such devices may even be used as a buoyancy aid for heavier articles, such as laptop computers, which maybe carried on and off of boats. Several such devices would then be adhered at spaced locations to the article requiring buoyancy safety. It is believed that in this way articles up to 10 kg in weight could be supported by plural flotation devices of this type, or such heavier articles could be supported by one or more larger flotation devices in accordance with the invention. 
     In a related development, some embodiments of the invention may include an additional outer jacket mounted around the casing in order to provide the means of attachment of a pad or pads of adhesive material without masking or overlying the apertures in the casing which are necessary to ensure quick and reliable penetration of water, as needed for rapid inflation of the bag and deployment of the float. Thus, such an outer jacket may be securely clipped or latched onto the casing, but may extend only partially around the casing in order to leave accessible at least some rows of the apertures in the casing. Additionally or alternatively, spacer means may be disposed between the outer jacket and the casing to ensure that a gap is maintained for ingress of water to the casing and through the apertures in the casing. 
       FIG. 10  illustrates a particular modified form of the device in which an illumination device in the form of a small LED unit  50  is mounted inside the inflatable bag  14 ′ in order to make the deployed float visible in the dark or poor light conditions. The unit  50  comprises a high-intensity LED  52  and three button cell batteries  54  mounted in a housing  56 . The housing  56  is formed with a bead-like projection  58  which enables it to be attached inside the bag  14 ′, preferably at a location remote from and opposite to the neck  15 ′ through which gas enters upon inflation, by an O-ring  59  fitted over the bead  58  from the outside of the bag  14 ′. 
     In an advantageous modification which is not illustrated here, the O-ring, which is of elastomeric material, may be formed with an additional larger loop, which can be suitably folded and stowed into the casing  10 ′ of the device in its initial condition. This larger loop will unfold automatically once the end cap  40 ′ is released and will facilitate retrieval of the deployed flotation device by means of a boat hook or the like. 
     As regards the LED unit  50 , a strip of insulating material  53  is provided which initially projects between contacts for the LED  52  and the batteries  54  in order to break the circuit. One end of this strip  53  is also trapped in the neck  15 ′ of the bag  14 ′ where it extends through the mounting plate  35 ′. Accordingly, as the bag  14 ′ inflates the strip  53  is automatically withdrawn from between the contacts. The circuit between the batteries  54  and the LED  52  is completed and the latter lights up. Optionally, suitable circuit means may be included for intermittent illumination of the LED  52 , thus greatly extending the possible battery life. 
     In all other respects the embodiment illustrated in  FIG. 10  is the same as that in  FIGS. 1 to 9  and the same reference numerals have been used to designate corresponding parts. 
     In a further modified embodiment a radio frequency transmitter could be mounted inside the inflatable bag in place of or as well as the LED unit. 
       FIGS. 11 ,  12  and  13  show three further embodiments, each of which has different retainer means for holding the valve  16  in a closed condition, and different means for release of same to allow the valve  16  to open compared to the preceding embodiments. However, all of these make use of at least one water reactive band of material to bring about release of the retainer means. 
     The embodiment shown in  FIG. 11  has its tubular valve member  19  biased to an open position by the spring  22  as in the previous embodiments, but instead of being held by a U-shaped spring  30  this valve member  19  is held against spring bias by a plate  60 , which itself is held in place by two water reactive bands  62  which extend around the container  12  from top to bottom. These bands  62  may be formed as previously described for the band  32  in the previous embodiments. This arrangement is simpler for assembly purposes during production compared to the previous embodiments, and avoids use of a special U-shaped spring, but it is equally effective in operation. 
     The embodiment shown in  FIG. 12  also has its tubular valve member  19  biased to an open position by the spring  22  as in the previous embodiments. In this case the U-shaped spring  30  is replaced by a lever  64  which has one end swingably attached (at  65 ) to the wall of the container  12  and its other end engaging around the valve member  19  behind the flange or collar  25 . The lever  64  is held down, against the bias of the spring  22  by a single water reactive band  66 , which again extends around the container  12  from top to bottom. This is even simpler for assembly purposes than the  FIG. 11  embodiment. To minimise the overall size of the device, the valve  16  is displaced to one side, with the band  66  being located near the centre. 
     An alternative possibility is for the lever  64  to be swingably attached to the container  12  at the other side compared to that shown in  FIG. 12 , namely close to the position of the valve  16 , with the band  66  then holding the lever  64  down closer to its free end. In this respect, the valve member  19  needs only to be raised a very small distance to allow inflation of the bag  14 . 
     In all other respects the embodiments of  FIGS. 11 and 12  are the same as that of  FIG. 10  and the same reference numerals have been used for corresponding parts. 
     The embodiment shown in  FIG. 13  has a significantly different arrangement in contrast to all the previous embodiments, as its tubular valve member  19  is biased to a closed position. This is achieved by a spring  22   1  acting between the cup-shaped valve body  26  and a flange  27   1  near the end of the member  19 . A lever  68  has one end swingably attached (at  69 ) to the wall of the container  12  and its other end free. The valve  16  is displaced to one side, as in the  FIG. 12  embodiment. In  FIG. 13  the valve  16  is shown close to the lever attachment  69 . The lever  68  engages the valve member  19  below the ring  24  which connects to the bag  14 ′, or below any other suitably provided flange. As shown, a second helical spring  70  is mounted between the top wall  13  of the container  12  and the lever  68 . As shown in the enlarged details A and B, this spring  70  is located between the upper and lower mounting plates  71 ,  72 . In detail A it is shown held under compression by a water reactive band  74  which is wrapped around these plates  71 ,  72 . As a unit, this compressed spring  70  wrapped by the band  74  is placed between the top wall  13  and the lever  68  upon assembly of the device. When the device is immersed in water the band  74  ruptures, as indicated in detail B, and the spring  70  urges the lever  68  upwards, overcoming the bias of the spring  22  to open the valve  16 . 
     Again in all other respects the embodiment of  FIG. 13  is the same as that of  FIG. 10  and the same reference numerals have been used for corresponding parts. 
     The invention is not limited to the specific details of the foregoing embodiments, and other variations in constructional details are possible within the scope of the invention as defined in claim  1 . In particular, it is envisaged that a significantly larger device may be produced, compared to the illustrated embodiments, with means of attachment to a larger article, such as a computer, and proportionately larger inflatable bag and larger gas supply for same so that a weight of up to or greater than 10 kg can be buoyantly supported by a single such device upon immersion in water. 
     Features described in conjunction with any particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.