Patent Publication Number: US-7900573-B2

Title: Submarine escape suit

Description:
The invention relates to submarine escape suits. 
     The submarine escape suit is used to escape from a submarine in an emergency. The suit is donned by a wearer within the submarine and the wearer then moves to an escape tower in the submarine where an inflatable chamber of the suit is connected to a supply of inflation gas, such as a supply provided in the submarine, to inflate the inflatable chamber and an ascent hood via relief valves. At the same time, the escape tower fills with water and an outer hatch opens to allow the buoyancy provided by the inflatable chamber and the hood to raise the wearer to the surface. A suit of this general type is shown in EP-A-0444400. 
     The buoyancy provided by the inflatable chamber and the hood must be carefully chosen to provide the correct speed of ascent of the wearer-neither too quickly nor too slowly. It is a problem that the chamber volume required for this purpose is often insufficient to support the wearer satisfactorily once the wearer reaches the surface. 
     According to a first aspect of the invention, there is provided a submarine escape suit comprising an ascent hood, a first inflatable chamber, an inflation tube leading to the first inflatable chamber and for connection to a supply of breathable gas to provide ascent buoyancy for the suit and breathable gas to the ascent hood, a second inflatable chamber and a gas supply carried by the suit and operable to inflate the second chamber to provide the suit with additional buoyancy. 
     According to a second aspect of the invention, there is provided a method of operating a submarine escape suit according to the first aspect of the invention, comprising inflating said first chamber under water using said inflation tube to provide ascent buoyancy and breathable gas to the ascent hood, ascending to the surface of the water and actuating the air supply to inflate the second chamber to provide the suit with additional buoyancy. 
     It can also be a problem that the first inflation chamber could become deflated due to damage or failure and provide insufficient buoyancy during ascent. 
     According to a third aspect of the invention, there is provided a method of operating a submarine escape suit according to the first aspect of the invention comprising inflating said first chamber under water using said inflation tube to provide ascent buoyancy and breathable gas to the ascent hood, ascending towards the surface of the water and, before reaching the surface of the water, actuating the air supply to inflate the second chamber to provide the suit with additional buoyancy. 
     In this way, additional buoyancy can be provided when the buoyancy of the first chamber is insufficient. 
    
    
     
       The following is a more detailed description of an embodiment of the invention, by way of example, reference being made to the accompanying drawings in which: 
         FIG. 1  is a partial view of the front and to one side of a submarine escape suit with an ascent hood omitted, with first and second inflatable chambers and with the first chamber partly cut away, 
         FIG. 2  is a similar view to  FIG. 1  but from the front and to the other side, 
         FIG. 3  is a similar view to  FIG. 1  but with an ascent hood, and 
         FIG. 4  is a section on the line X-X of  FIG. 2 . 
     
    
    
     Referring to the drawings, the submarine escape suit is a garment with a front panel  10 , a rear panel  11 , a left arm  12 , a right arm  13 , a left leg  14 , a right leg  15 , a neck portion  16  and a head portion  17 . The left arm  12  and the right arm  13  terminate in respective cuffs, one of which is shown at  18  in  FIGS. 1 ,  2  and  3 . The left leg  14  and the right leg  15  terminate in respective foot covers (not shown). The head portion  17  is intended to cover the head of the wearer  19  and includes a face aperture  20 . The suit is made from portions of weldable material such as polyurethane (PU) coated fabric. Access to the suit is via an elongate zip  21  extending from the neck portion  16  down the centre of the front panel  10 . 
     The suit includes an ascent stole  22  in the form of an elongate inflatable chamber having first and second ends  23 ,  24  extending over the front panel  10  and an interconnecting central portion  25  extending over the rear panel  11  around the neck portion  16 . The ascent stole  22  overlies a life preserver stole  26 . The life preserver stole  26  is formed by an elongate inflatable chamber with a first end  27  and a second end  28  overlying the front panel  10 . The first and second ends  27 ,  28  are interconnected by a central portion  29  extending over the rear panel  11  and around the neck portion  16 . 
     The ascent stole  22  and the life preserver stole  26  are formed as follows. 
     First, a first generally U-shaped sheet of weldable material  39 , such as a PU coated fabric, is placed around the neck portion  16  of the suit and over the front panel  10 . This portion, seen in  FIG. 4 , is then welded around its periphery along a weld line  40  to the front panel  10  and the rear panel  11 . This forms the life preserver stole  26 . A second U-shaped sheet of weldable material  41  such as a PU coated fabric  41  is then laid over the first piece of material and welded around its edges to the first piece along a weld line  42  inwardly of the weld line  40  for the first material  39 . This forms the ascent stole  22 . As seen in  FIG. 4 , the ascent stole  22  includes two internal reeds  30  of material interconnecting the second sheet  41  and the first sheet  39 , to limit the expansion/volume of the chamber when inflated. There may be one such reed  30  or three or more such reeds  30 . 
     The ascent stole  22  is provided with an inflation tube  31  that leads from the ascent stole  22  along the left arm  12  to terminate in a connector  32  at the left cuff  18 . The connector  32  is for connection to a supply of breathable air which may, for example, be in a submarine. In some applications, the ascent stole ( 22 ) is inflated from an independent bottle supply (not shown) mounted in a pocket on the suit. The ascent stole  22  also includes two relief valves  33 . The function of these will be described below. 
     The life preserver stole  26  is connected to an air supply formed by a valve  34  and source of gas under pressure  35 . The valve  34  is operated by pulling on a toggle  36  connected to a cord  37 . 
     The suit is completed by an ascent hood  38  seen in  FIG. 3 . The ascent hood  38  is a fabric member that incorporates a clear plastic visor and covers the head of a wearer and has its periphery generally engaging around the outer periphery of the ascent stole  22  so that the ascent hood covers the relief valves  33 . 
     It will be appreciated that the submarine escape suit shown in the drawings may also include other items such as a liferaft (not shown) with its own inflation system contained in a pocket on the front or to one side of the suit and connected to the suit by a cord. 
     In use, the suit is held in a packed condition in a submarine. In an emergency or for training, the suit is unpacked, the zip  21  opened and the suit donned by a wearer. This is as shown in  FIGS. 1 ,  2  and  3 . 
     The wearer then moves into an escape tower of a submarine. Once in the escape tower, the wearer connects the connector  32  to a supply of breathable gas, such as an air supply provided in the submarine, via an outlet in the escape tower. The breathable gas inflates the ascent stole  22  and passes through the relief valves  33  into the ascent hood  38  to provide a supply of breathable gas for the wearer. At the same time, the escape tower fills with water and, once filled, an exit opens. 
     The natural buoyancy of the wearer, together with a calculated buoyancy of the ascent chamber and the hood  38  causes the wearer to leave the chamber and ascend towards the surface at a controlled rate determined at least partially by the volume of the ascent stole  22  and the hood  38 . As the pressure in the ascent stole  22  increases, air is relieved by the relief valves  33  into the hood  38  where it can be used for breathing by the wearer. 
     Once the wearer reaches the surface, the wearer can pull the toggle  36  and the cord  37  to actuate the valve  34  to connect the source of gas  35  to the life preserver stole  26 . The effect of this is to inflate the life preserver stole  26 . This provides the suit and wearer with additional buoyancy, which may be sufficient to turn the wearer onto the wearer&#39;s back if the wearer is initially face down in the water. The volume of air in the ascent stole  22  required to ensure correct ascent may in many cases be insufficient to achieve this. In addition, the increased volume provided by the life preserver stole  26  ensures that the wearer is better supported on the surface than would be the case with the ascent stole only. The inflated volume of the life preserver stole  26  may be greater than the inflated volume of the ascent stole  22 . 
     In an alternative mode of operation, the life preserver stole  26  can be used in the event that the ascent stole  22  fails or provides insufficient buoyancy during ascent. In this case, the wearer can operate the valve  34  via the toggle  36  during ascent to inflate the life preserver stole  26  to provide additional buoyancy to the suit and thus faster ascent. 
     It will be appreciated that there are a number of alterations that can be made to the arrangement described above with reference to the drawings. Although the ascent stole  22  and the life preserver stole  26  are shown as overlying one another, this need not be the case; they could be laterally spaced from one another. In addition, although the ascent stole  22  and the life preserver stole  26  are shown as having a generally U-shaped configuration extending over the front panel  10  and around the neck portion  16  and the rear panel  11 , they could be of any convenient shape. 
     Although the air supply for the life preserver stole  26  is shown as being manually operable, additionally or alternatively, it could be operated automatically in the event that the wearer in unconscious when reaching the surface to ensure that the wearer is always turned onto the wearers back. 
     The life preserver stole  26  is shown formed by a single chamber; it could be formed by two or more chambers fed by a single air supply or by individual air supplies.