Abstract:
When carrying out a water emergency rescue, to rescue, particularly from a helicopter, a plurality of victims in a wide area of water without any drowning occurring. [Solution] A water rescue device is formed from: a hollow tube-shaped air chamber which is stored in an evacuated state; a gas injection mechanism which injects a pressurized gas in the air chamber; a pressurized gas tank which retains the pressurized gas; and a case which houses the air chamber, the gas injection mechanism, and the pressurized gas tank. When the case is lowered upon a water surface from a helicopter, the pressurized gas in the pressurized gas tank is injected via the gas injection mechanism into the air chamber, and the air chamber is released from the case, expanded in a swirl shape, and deployed on the water surface.

Description:
TECHNICAL FIELD 
     The present invention relates to a water rescue device used to save human lives on the water from a helicopter or the like, and more particularly to a water rescue device which allows lifesaving in a wide area. 
     BACKGROUND ART 
     In recent years, aircraft and ships have been growing in size. Consequently, once an accident occurs, there can be a large number of victims. In particular, if an accident occurs on, in, or above a sea, lake, river or the like, there can be a large number of people who need to be rescued (hereinafter referred to as rescuees). Besides, swollen rivers and inundated regions caused by a natural disaster such as a heavy rain, typhoon, tsunami, or the like also produce rescuees. A search and rescue operation by a helicopter from the sky is especially effective in saving such rescuees. 
     Therefore, a rescue method has conventionally been available, as described in Patent Literature 1, in which a rope is thrown from a helicopter, allowing a rescuee to catch the rope, and a rescuer approaches the rescuee by water or descends from the helicopter to save the rescuee. Also, there is a method, as described in Patent Literature 2, which involves dropping a circular escape bag containing a rescue net thereinside from a helicopter and saving any rescuee caught in the rescue net. 
     However, there is a problem that with either method, coverage of rescue operations is extremely limited, and when there is a severe storm or high waves, it is very difficult to drop a rope or escape bag in a rescuable range for rescuees, making it sometimes impossible for the rescuee to reach the rescue device, and consequently rendering the rescue device useless. 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Literature 1: Japanese Patent Laid-Open No. 2004-122967 
         Patent Literature 2: Japanese Patent Laid-Open No. 5-178285 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     The problem to be solved is the difficulty to deploy a rescue device to save rescuees on the water in a large area from a helicopter or the like during a rescue operation in a water accident. 
     Solution to Problem 
     The present invention is a water rescue device intended to solve the above problem, comprising: a hollow tubular air chamber configured to become spiral when filled with gas; a gas filling mechanism adapted to fill the gas into the air chamber; and a compressed gas cylinder adapted to compress and hold the gas, wherein the compressed gas from the compressed gas cylinder is filled into the air chamber by the gas filling mechanism, unfolding the air chamber into a spiral shape such as an Archimedean spiral. Consequently, the air chamber, which becomes spiral-shaped when filled with gas, can be deployed over a wider area on the water surface than an annular or linear one. 
     The present invention further comprises a casing adapted to house the air chamber, the gas filling mechanism, and the compressed gas cylinder, wherein the air chamber is released from the casing when the casing is dropped onto a water surface. Consequently, the water rescue device can be made ready for use by simply dropping the casing containing necessary mechanisms. 
     According to another embodiment, the present invention further comprises: a plurality of independent air chambers; and a connecting member adapted to connect the plurality of independent air chambers with each other. This reduces the size of individual air chambers and thereby reduces gas filling time. 
     Advantageous Effect of Invention 
     The water rescue device according to the present invention has the advantage of being able to reliably save rescuees because the air chamber can be deployed over a wider area and brought close to the rescuees even in a stormy weather, allowing the rescuees to cling to the air chamber for increased buoyancy and wait for a full-scale rescue operation without drowning. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a configuration diagram of a water rescue device according to a first embodiment of the present invention. 
         FIG. 2A  is an operation explanation diagram of the water rescue device according to the first embodiment of the present invention. 
         FIG. 2B  is an operation explanation diagram of the water rescue device according to the first embodiment of the present invention. 
         FIG. 2C  is an operation explanation diagram of the water rescue device according to the first embodiment of the present invention. 
         FIG. 3  is a plan view of an air chamber of the water rescue device according to the first embodiment of the present invention. 
         FIG. 4A  is another plan view of an air chamber of the water rescue device according to the first embodiment of the present invention. 
         FIG. 4B  is another plan view of an air chamber of the water rescue device according to the first embodiment of the present invention. 
         FIG. 5  is a configuration diagram of additional part of the water rescue device according to the first embodiment of the present invention. 
         FIG. 6  is a plan view of an air chamber of a water rescue device according to a second embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     A first embodiment of the present invention will be described with reference to drawings.  FIG. 1  is a configuration diagram of a water rescue device  1  according to the first embodiment of the present invention, where the water rescue device  1  includes an air chamber  10 , a gas filling mechanism  20 , a compressed gas cylinder  30 , and a casing  40 . 
     In  FIG. 1 , the air chamber  10  is evacuated, folded, and housed in the casing  40 . The air chamber  10  is made of a polymer (fiber, resin, or rubber) film. When inflated by being filled with gas, the air chamber  10  has a hollow tubular shape with a substantially circular cross section and without a partition. When inflated, the air chamber  10  is formed into a spiral shape made up of plural linear portions  11   a  to  11   x  joined together. Desirably, the spiral is shaped as an Archimedean spiral in which spiral lines are spaced evenly with each other. The Archimedean spiral is approximated by line segments as appropriate to form the air chamber  10 . For example, one circle (360 degrees) is approximated by about eight linear portions. Note that the method for approximation is not limited to this. Near the center of the Archimedean spiral, in particular, a simpler approximation is used because a high level of approximation by straight lines complicates the shape too much. 
     Regarding the polymeric material of air chamber  10 , polyurethane resin (polyurethane rubber) is excellent in terms of strength and the like, but this is not restrictive. 
     Also, the linear portions  11  of the air chamber  10  are formed using a known technique, for example, by joining two pieces of planar polymer film by a high-frequency welding process. Furthermore, by joining the linear portions of the air chamber  10  with each other at a section with an equal angle to an axial direction of the linear portion (congruent elliptic portions), the air chamber  10  can be formed into a desired shape so as to be maintained in a desired shape when inflated. Incidentally, the material and manufacturing method of the air chamber  10  as well as the method for approximating the spiral shape are not limited to those described above, and reinforcing members may be added and the material and thickness of the polymer film may be changed. 
     As shown in  FIG. 1 , one end (terminal side of the spiral) of the air chamber  10  is sealed. On the other hand, another end (central side of the spiral) of the air chamber  10  is provided with a gas filling mechanism  20 . The gas filling mechanism  20  includes a check-valve  21  installed on a flow path leading to the air chamber  10 , a solenoid valve  23  installed on the side of the compressed gas cylinder  30 , an air line  22  interconnecting the check-valve  21  and the solenoid valve  23 , and a battery  24  adapted to actuate the solenoid valve  23 . The check-valve  21  here does not require any power in particular, and passes a fluid only in one direction. The solenoid valve  23  is normally closed, and opens the flow path by operating a solenoid when energized by the battery  24 . 
     Furthermore, the gas filling mechanism  20  includes a signal receiver  25  adapted to receive an external command signal for opening/closing the solenoid valve  23 , where the signal receiver  25  is wired to the solenoid valve  23 . 
     The compressed gas cylinder  30 , which is adapted to contain a compressed gas, is constructed using a shape and material capable of withstanding high pressures. Desirably, compressed air is sealed therein as the compressed gas. 
     The casing  40  includes a cylinder  41  made of a thin steel sheet with its one end open, and a cover  44  adapted to close the open end. The folded air chamber  10 , the gas filling mechanism  20 , and the compressed gas cylinder  30  are housed in the casing  40 . Seats  42  are provided in the casing  40  to fix the compressed gas cylinder  30 . 
     Also, a metal fitting  43  adapted to fix a holding rope  2  is installed outside the bottom of the cylinder  41  of the casing  40 . Furthermore, at the open end of the cylinder  41  of the casing  40 , the cover  44  is held by a hinge  45  and a magnetic catch  46 , where the hinge  45  is adapted to pivotally connect the cover  44  to the cylinder  41  and the magnetic catch  46  is adapted to openably and closably lock the cover  44  onto the cylinder  41 . 
     Operation of the water rescue device with this configuration will be described with reference to drawings.  FIGS. 2A to 2C  are operation explanation diagrams according to the first embodiment of the present invention. The water rescue device  1  is caused to descend into the air by being suspended by the holding rope  2  from a helicopter H as shown in  FIG. 2A , and then dropped by removing the holding rope  2  from the helicopter H as shown in  FIG. 2B . When the water rescue device  1  reaches the water surface, the air chamber  10  is pushed out of the water rescue device  1 , and the air chamber  10  filled with gas is unfolded into a spiral shape on the water surface as shown in  FIG. 2C . 
     The operation of the water rescue device will be described in more detail with reference to  FIGS. 2A ,  2 B, and  2 C. When the water rescue device  1  is mounted on the helicopter H, the air chamber  10  is folded and is housed in the casing  40  together with the gas filling mechanism  20  and the compressed gas cylinder  30 . Furthermore, the casing  40  is mounted inside the helicopter H and connected to the helicopter H via the holding rope  2 . When the helicopter H arrives at a location over the site in need of the water rescue device, the casing  40  is lowered by a distance equal to the length of the holding rope  2 . Alternatively, instead of being mounted inside the helicopter H, the casing  40  may be carried by being suspended from the holding rope  2 . 
     When the holding rope  2  is disconnected from the helicopter H with the casing  40  being suspended, the casing  40  drops toward the water surface. 
     When the casing  40  reaches the water surface, a signal to open the solenoid valve  23  is sent to the signal receiver  25  by radio communication and the solenoid valve  23  is actuated by the signal and power of a battery  24 , opening the flow path, where the signal is either issued manually by the crew or issued automatically according to a predetermined condition. Consequently, the compressed gas in the compressed gas cylinder  30  starts to flow to the air line  22 . The check-valve  21  is installed at a tip of the air line  22 , and the gas flowing in this direction flows into the air chamber  10  without being checked by the check-valve  21  as in the forward direction. 
     Consequently, the air chamber  10  starts to inflate. The inflating air chamber  10  applies outward pressure to the cover  44  of the casing  40 , and when the pressure exceeds holding power of the magnetic catch  46 , the cover  44  opens by pivoting on the hinge  45 . Consequently, the air chamber  10  is pushed out of the casing  40  and continues to inflate further. 
     As shown in  FIG. 3 , the air chamber  10  is shaped to be approximated by an Archimedean spiral when inflated. When filled with a predetermined volume of gas from the compressed gas cylinder  30 , the air chamber  10  shaped to be similar to an Archimedean spiral is deployed on the water surface. 
     The check-valve  21  installed in the flow path leading to the air chamber  10  prevents the gas from flowing backward from the air chamber  10  to the air line  22 , and thereby keeps the air chamber  10  inflated. 
     In this state, since the spiral line is spaced almost evenly, with the inflated air chamber  10  deployed in an extensive area on the water surface, the rescuees can reach the air chamber  10  if they move approximately half the spacing of the spiral line at the maximum by swimming or the like. Even if the rescuees do not swim, it is conceivable that they will reach the air chamber  10  with the rescuees themselves or the water rescue device being carried by waves. Then, the rescuees can increase buoyancy by clinging to the air chamber  10 . In this way, the rescuees can maintain their strength until an eventual rescue operation without drowning and increase the probability of being saved. 
     The air chamber  10  is floating on the water surface in an inflated state by being accompanied with the gas filling mechanism  20 , the compressed gas cylinder  30 , and the casing  40 . Thus, after the water rescue device is used, the air chamber  10  can be recovered, as it is, for reuse. However, if airtightness of the air chamber  10  can be maintained, all or part of the gas filling mechanism  20 , the cylinder  30 , and the casing  40  may be configured to be separable from the air chamber  10 . This will further increase the buoyancy of the air chamber  10 , making it possible to save a larger number of rescuees although it will become difficult to reuse the air chamber  10 . 
     Also, although it has been stated that the water rescue device  1  is connected to the helicopter H via the holding rope  2  before being dropped onto the water surface, the casing  40  may be dropped directly without using the holding rope  2  from the beginning. This can simplify the mechanism. 
     Also, although it has been stated that alternatively the water rescue device  1  is dropped by removing the holding rope  2  from the helicopter H, the water rescue device  1  may be lowered to the water surface while being held by the holding rope  2  as long as the flight of the helicopter H is not endangered. This will make it possible to reliably place the water rescue device at a desired position. 
     The spiral shape of the air chamber  10  may be not only an exact spiral shape, but also a shape made up of linear portions approximating a spiral or a shape similar to a spiral. Other examples of the spiral shape include, but are not limited to, a shape similar to a lower-case “e” such as shown in  FIG. 4A  and a square spiral such as shown in  FIG. 4B . The shape can be selected by taking into consideration the size of the deployment area, ease of a production method, and various other points. 
     Although it has been stated that the air chamber  10  is housed in the casing  40  in a folded state, depending on the structure and manufacturing method of the air chamber  10 , the air chamber  10  may be housed in a coiled state without being folded. This sometimes may allow good storage conditions to be maintained. 
     The casing  40  may have any internal structure and component as long as the casing  40  can contain the air chamber  10 , the gas filling mechanism  20 , and the compressed gas cylinder  30  and can release them as required. Also, the material is not limited to a thin steel sheet, and any material such as another metal, plastic, or cloth may be used as long as contents can be held securely during storage or transit. 
     The mechanism for opening the casing  40  to inflate the air chamber  10  is not limited to the mechanism which detaches the magnetic catch as the air chamber  10  inflates, and any method may be used, including another catch mechanism such as a ball catch, a latch mechanism, a mechanism configured to open the casing when part of the casing formed to have low strength is broken by a shock, or a mechanism configured to open the casing when part of the casing dissolves or falls in strength by getting wet. 
     Furthermore, as shown in  FIG. 5 , a thin string  12  may be attached beforehand to an outer periphery of the air chamber  10  as a handhold for rescuees. This will increase rescue efficiency although the structure of the air chamber  10  will become complicated. Also, without limiting to a thin string, handles or the like capable of supporting the rescuees may be provided. 
     The compressed gas is not limited to air, and may be another gas which is low in explosion risk and toxicity. For example, inert gas such as nitrogen or helium may be used as well. The inert gas, which does not contain impurities, does not cause ice formation, unlike air. Liquefied carbon dioxide may be used alternatively. Although measures need to be taken against possible formation of dry ice during filling, the liquefied carbon dioxide, which can reduce the size of the compressed gas cylinder thanks to high compressibility as a result of liquefaction, is effective in downsizing the entire water rescue device. 
     Although it has been stated that to fill the air chamber  10  with gas from the compressed gas cylinder  30 , the gas filling mechanism  20  made up of the check-valve  21 , the solenoid valve  23 , and the air line  22  adapted to interconnect the check-valve  21  and the solenoid valve  23  is provided, the check-valve  21  and the solenoid valve  23  may be interconnected directly by omitting the air line  22 , or the check-valve  21  and the solenoid valve  23  may be combined into a single valve having the functions of the two valves. This is effective in downsizing the device. 
     Although it has been stated that one gas filling mechanism  20  is installed on the end at the center of the spiral of the air chamber  10 , the gas filling mechanism  20  may be installed at an end opposite the end at the center of the spiral. Also, the gas filling mechanism  20  may be installed at each end of the spiral of the air chamber  10 . When the gas filling mechanisms  20  are installed at both ends, the time required for gas filling can be reduced. 
     Also, although it has been stated that the air chamber  10  is constructed as a single space without any partition, the air chamber  10  may be partitioned into plural spaces (small air chambers). In that case, either the gas filling mechanism  20  may be installed for each small air chamber, or the gas may be filled into respective small air chambers from a single gas filling mechanism  20  via a common flow path and respective check-valves. Consequently, even if the film material of the small air chambers is damaged, resulting in gas leakage, the leakage is confined to part of the small air chambers, making it possible to avoid a total loss of buoyancy. 
     Although it has been stated in the above description that the solenoid valve  23  is actuated by a radio signal and a battery, when the casing  40  is lowered to the water surface by the holding rope  2 , electric power and signals may be provided via an electric cable run along the holding rope  2  and connected to the solenoid valve  23  in the casing  40 . This eliminates the need to build the battery  24  into the casing  40  and thereby allows the main body of the device to be downsized. 
     Regarding the method for actuating the solenoid valve  23 , instead of using radio commands, the solenoid valve  23  may be actuated by a timer connected to the solenoid valve  23  with an actuation time preset before a drop, by an acceleration sensor adapted to turn on a switch on impact at the time of a drop, or by turning on a switch adapted to make a wire connection by getting wet with water after a drop. Also, the solenoid valve may be replaced by a valve provided with a mechanism adapted to get released on impact at the time of a drop or a valve provided with a mechanism adapted to get released as a sealed portion becomes wet after a drop. In either case, the valve is actuated automatically without any particular command, causing the air chamber  10  to start inflating and thereby making it possible to prevent trouble caused by human operations or radio communications. 
     Next, a second embodiment of the present invention will be described with reference to drawings.  FIG. 6  is a configuration diagram of a water rescue device  1  according to the second embodiment of the present invention, where the water rescue device  1  includes plural independent air chambers  10 , a gas filling mechanism  20 , a compressed gas cylinder  30 , and a connecting member  50  adapted to connect the plural air chambers with each other. The connecting member  50  may be a rigid body made of metal or plastic; a non-rigid body such as a rope, cord, chain, ring, or coil; or an elastic body such as rubber. Also, the air chambers  10  and connecting member  50  may be connected pivotally or fixed to each other non-pivotally. Also, the shape of the air chamber  10  filled with gas may be a linear tubular shape, curved tubular shape, or sharply bent tubular shape. Furthermore, the shape of the connecting member  50 , especially in the case of a rigid body, may be a linear shape, curved shape, or sharply bent shape. Note that the connecting member  50  may be made up of a continuous body, with the air chambers  10  attached thereto, rather than separate pieces. If the materials and shapes of the air chambers and the connecting member are selected appropriately, the air chambers and the connecting member can be deployed so as to form a spiral shape. In this way, the provision of plural independent air chambers  10  achieves the advantage of being able to reduce the size of the individual air chambers  10  as well as to reduce the gas filling time. Also, a float  60  may be connected to the first air chamber at the center of the spiral shape. 
     The water rescue device according to the present invention may be dropped from an airplane instead of a helicopter. Then, a rapid rescue operation can be expected than when a helicopter is used, and the feature of the present invention, i.e., the capability to deploy the water rescue device over a wide area, allows the air chambers to be deployed in the vicinity of rescuees in spite of a high flying speed. 
     Also, the water rescue device according to the present invention may be dropped from a ship. The water rescue device according to the present invention is useful when it takes time before a full-scale rescue operation by means of life boats. 
     Furthermore, the water rescue device according to the present invention can be thrown from land. For example, in saving rescuees swept away or isolated by a swollen river or the like, if the water rescue device according to the present invention is thrown from a riverbank or bridge, the air chambers can be deployed over a wide area, making it possible to reliably save the rescuees. Of course, the water rescue device according to the present invention can be used not only in rivers, but also in lakes, at the seaside, and in inundated zones at the time of a flood. 
     REFERENCE SIGNS LIST 
     
         
           1  Water rescue device 
           2  Holding rope 
           10  Air chamber 
           11  Linear portions making up the air chamber 
           20  Gas filling mechanism 
           23  Solenoid valve 
           30  Compressed gas cylinder 
           40  Casing 
           50  Connecting member 
           60  Float 
         H Helicopter