Abstract:
A roller door system ( 100 ) particularly for opening and closing a doorway ( 120 ) defined in the wall of a lightweight structure ( 110 ) such as a marquee, hangar, field hospital, emergency shelter and the like. The door system comprises a rollable door ( 150 ) secured, in use, along one edge of the doorway ( 152 ); a roller ( 140 ) for rolling and unrolling the rollable door about the roller; an opening mechanism and a closing mechanism for controlling the deployment of the rollable door by translating the roller across the doorway; and reusable sealing means ( 135, 136, 155, 156 ) for sealing between the lateral margins of the rollable door and the doorway; characterized in that the rollable door comprises a plurality of collapsible hoses ( 165, 166 ) connected to a pressurized fluid power system ( 160, 161, 163 ) such that in use a positive pressure applied to the fluid power system causes the rollable door to unroll from the roller and controls the deployment of the rollable door.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is the U.S. national phase of International Application No. PCT/GB2014/000428 filed on Oct. 23, 2014, and published in English on May 7, 2015 as International Publication No. WO 2015/063441 A1, which application claims priority to Great Britain Patent Application No. 1319194.5 filed on Oct. 30, 2013, the contents of all of which are incorporated herein by reference. 
     TECHNICAL FIELD OF THE INVENTION 
     The invention relates to a roller door system particularly, but not exclusively, suitable for use with tents and other lightweight, temporary or rapidly deployable structures, including, but not limited to: marquees, hangars, field hospitals and emergency shelters. More particularly the roller door system is suitable for sealing an opening to prevent ingress of smoke, contaminated air or particulates into a structure. 
     BACKGROUND TO THE INVENTION 
     Roller blinds, shutters and doors of various designs are well known. A simple roller blind, shutter or door comprises a roller mounted above a window, doorway or other opening and a sheet of flexible or slatted material wound onto the roller, which can be deployed into an unwound configuration to cover or close the opening. The opening may be provided with guide channels at either side in order to anchor the sides of the closed blind, shutter or door for increased stability or security. The opening and closing operation can be performed manually, for example using a side chain or cord, or can be motorised, for example by incorporating a motor drive mechanism within the roller. 
     Roller door systems are designed to allow people and equipment to move quickly through the doorway without obstruction e.g. by keeping the threshold as clear as possible, and without being inconvenient to operate e.g. by being too heavy, too slow or prone to jamming. 
     In situations where it is necessary to seal an opening against the ingress of smoke, contaminated air or particulates it is known to use a roller door system in which the top of the sheet material is secured to the top of the door frame and the roller itself moves relative to the opening. As the roller moves down over the opening the side edges of the sheet material can be progressively sealed to the door frame, for example by means of magnetic strips or hook and loop material. U.S. Pat. No. 5,383,510 (Allen) discloses an example of such a system. 
     It is an aim of the invention to provide an improved roller door system particularly, but not exclusively, suitable for use with tents and other lightweight, temporary or rapidly deployable structures, including, but not limited to: marquees, hangars, field hospitals and emergency shelters. 
     SUMMARY OF THE INVENTION 
     According to an embodiment of the invention, there is provided a roller door system, for opening and closing a doorway defined in the wall of a structure, comprising a rollable door secured, in use, along one edge of the doorway; a roller for rolling and unrolling the rollable door about the roller; a door opening means and a door closing means for controlling the deployment of the rollable door by translating the roller across the doorway; and reusable sealing means for sealing between the lateral margins of the rollable door and the doorway; characterised in that the door closing means comprises a pressurised fluid power system. 
     Since the door is rollable it can be easily transported and stored. Furthermore, it may be made from a lightweight flexible woven or non-woven sheet material such as PVC or nylon/polyester thereby minimising bulk and weight. The doorway may be defined by a rigid door frame, for example in a lightweight, temporary or rapidly deployable structure, but the roller door system is particularly suitable for use with tented or flexible structures since a rigid door frame is not required. The doorway may be defined by a flexible door frame which reduces bulk and weight of the whole structure and allows for use on over-pressured tents 
     Advantageously, the pressurised fluid power system comprises a plurality of collapsible hoses associated with the rollable door and configured to cause the rollable door to unroll from the roller when expanded by fluid. The collapsible hoses may be mounted on the surface of the rollable door or may be integral to the thickness of the door and are preferably directed substantially parallel to the direction in which the door is rolled and unrolled, so that filling the collapsible hoses with fluid causes the hoses to expand unrolling the door and driving the roller across the doorway. This arrangement requires few rigid components and therefore has advantages of reduced weight and reduced bulk. 
     The pressurised fluid power system may be pneumatic or hydraulic depending on the particular application; however a hydraulic system is generally preferred because the relative incompressibility of liquid makes it safer than a high pressure compressed gas system. Since a permanent reservoir of hydraulic oil would increase the bulk, weight and fire risk of the roller door system it may be particularly convenient to use water or a water based solution as the hydraulic fluid. In this case the hydraulic reservoir can be filled on location and emptied before transportation and storage. In particularly cold weather it may be desirable to mix an antifreeze additive into the water. 
     Whilst the pressurised fluid power system may conveniently be operated by an electric pump an alternative power source such as a battery pack should be provided in case of emergencies. However, in some situations it may be preferred to provide a manually operated pump for emergency use. 
     A valve is conveniently provided to close the fluid system in order to maintain the door closed configuration so that the pump does not have to run continuously once the door is closed. The valve is opened, thereby releasing the fluid pressure, when it is desired to open the door. 
     Advantageously, the rollable door when unrolled may overlap the lateral margins of the doorway and is mounted externally with respect to the wall of the structure. The reusable sealing means are provided between the overlapping lateral margins of the door and doorway. Mounting the roller door externally of the structure means that a person can exit the structure in an emergency (e.g. a fire) by simply pushing against the rollable door from the inside to unseal the reusable seals. The rollable door does not, therefore, have to be rolled up around the roller in order for a person to exit the structure quickly when required. 
     The reusable sealing means preferably provide substantially air-tight seals between the lateral margins of the door and the doorway in order to prevent external contaminants from entering the structure. In certain applications it is known to maintain an over-pressure within a structure by means of blowers and filters. In such applications the flow of air from inside the structure to outside is normally controlled via vents and doorways are expected to be effectively sealed to minimise the escape of air. The door and doorway may be sealed and unsealed from one another whilst closing and opening the door respectively. Preferably, the reusable sealing means comprise flexible magnetic strips. Other reusable sealing means such as zip fasteners or hook and loop fasteners can be used, although it is generally more difficult to achieve substantially air-tight seals. Furthermore, the seal provided by a flexible magnetic strip may be more easily broken by pushing against it in the event of an emergency. The use of flexible magnetic strips does not require any effort on the part of an operator to make the seal, since unrolling the door places the margins of the door and the doorway in sufficiently close proximity for the seal to be automatically made by magnetic attraction. For example, a magnetic strip mounted along the length of the lateral margin of the doorway may magnetically attract and make a seal with a flexible magnetic strip mounted along the length of the appropriate lateral margin of the rollable door. The magnetic strips are made of magnetic materials. Typically, for each reusable seal, one of the magnetic strips is magnetised, and the other one of the magnetic strips is not magnetised. If desired then both strips could be magnetised, with opposite polarity, in order to increase the strength of the seal. 
     A similar substantially air-tight reusable seal is preferably also provided between the rollable door and a final side or threshold of the doorway to improve the air-tight seal of the fully closed door. Furthermore the rollable door may be secured along the first side of the doorway by a reusable seal, however in some cases it may be desirable for this seal to be more robust and in that case a zip fastener or hook and loop fasteners may be more suitable for securing the rollable door along the first side of the doorway. 
     The door opening means conveniently comprises at least one spring biased to roll the rollable door about the roller, thereby tending to move the roller into its door open position. The spring constant can be designed to overcome the pressure in the fluid power system in order to roll up the door; for example to evacuate the collapsible hoses, returning fluid to its reservoir; as the door rolls about the roller. Alternatively, a pump may be used to reverse the pressure in the fluid power system so that the spring is only required to separate the reusable seals (unless this must be done manually, for example in the case of zip fasteners) and rollup the door. The at least one spring could be fitted within the roller, however it may be convenient to use rolled ribbons of spring material mounted to the rollable door. Such ribbons could be mounted adjacent, laminated to, or within the collapsible hoses or could form the magnetic strips, so that part of the reusable sealing means also acts as the door opening means. In any case the relative forces applied by the pressurised fluid power system, the reusable seals (unless requiring manual unsealing) and the spring bias must be carefully designed to provide ease of door closure, efficient air-tight seals and safe and controlled door opening. 
     Advantageously, the roller may be provided with a tether and a toggle at each of its ends, so as to facilitate correct alignment of the rollable door. The toggle may be designed to cooperate with a guide channel provided in the wall of the structure parallel to the lateral sides of the doorway. Accordingly, the roller can move up and down the doorway whilst tethered to the wall, the toggle sliding within the channel. This provides additional support and strength to the system and ensures the correct alignment of the door relative to the doorway. Such a system of tethering is particularly advantageous in situations in which an over-pressure is maintained within the structure, since it ensures that the reusable seals are correctly aligned as the door is closed even if there is bulging at the doorway. 
     Alternatively, the toggle may be designed to attach to, or act as, the slider of an interlocking fastener, such as, for example, a zip fastener. A first row of zip teeth of the zip fastener may be provided along the lateral sides of the rollable door and a second row of zip teeth may be provided in the wall of the structure parallel to the lateral sides of the doorway, the first and second rows of zip teeth being designed to cooperate with one another. As the roller moves down and up the doorway, the slider engages and disengages the zip fastener. Again, this provides additional support and strength to the system and ensures the correct alignment of the door relative to the doorway. Moreover, a zip fastener can readily be integrated with materials typically used in tented or flexible structures. 
     According to another embodiment of the invention, there is provided a tent comprising the roller door system as hereinbefore described, wherein the doorway is defined in a flexible wall of the tent. There is no requirement for a rigid door frame so the roller door system according to the invention is well suited to use with lightweight, flexible structures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       Embodiments of the invention will now be described by way of example only and with reference to the accompanying drawings, in which: 
         FIG. 1  shows a schematic diagram of a roller door system according to a first embodiment of the invention; 
         FIG. 2  shows a schematic diagram of a roller door system according to a second embodiment of the invention; 
         FIG. 3  shows a schematic diagram of a plan view of the second embodiment of the invention; The drawings are for illustrative purposes only and are not to scale. 
         FIG. 4  shows a schematic diagram of a roller door system in the doorway of a tent; 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a wall of a temporary emergency shelter including a roller door system  100 . The temporary emergency shelter has a wall  110  made from a flexible plastic sheet material having an opening with a left side  111 , a top side  112 , and a right side  113  which together define a doorway  120  through the plastic sheet wall  110 . The plastic sheet wall  110  as shown in  FIG. 1  is viewed from outside of the shelter. 
     The roller door system  100  comprises a rollable door  150  and a roller  140 , the roller  140  being attached to the bottom portion of the rollable door  150 . A top portion  152  of the rollable door  150  is permanently attached to the plastic sheet wall  110  along the top side  112  of the doorway  120 . The rollable door  150  is wider than the doorway  120  and is arranged to overlap the left and right sides  111  and  113  of the doorway  120  on the outer surface of plastic sheet wall  110 . 
     The roller  140  is aligned horizontally across the doorway  120 , and is used for rolling and unrolling the rollable door  150  about the roller  140  to respectively open and close the doorway  120 . Since the top portion  152  of the rollable door is permanently or semi-permanently attached to the plastic sheet wall  110  along the top side  112  of the doorway  120 , rolling and unrolling the roller  140  causes it to be translated up and down the doorway  120  respectively. 
     The roller door system  100  further comprises left and right side magnetic strips  135  and  136  that are aligned along the left and right sides  111  and  113  of the doorway  120  respectively and that are mounted on the plastic sheet wall  110 . Corresponding left and right side magnetic strips  155  and  156  are aligned and mounted along left and right sides of the rollable door  150 . As the rollable door  150  is unrolled from the roller  140 , the magnetic strips  155  and  156  mounted on the rollable door  150  are attracted to and make an air-tight seal with the magnetic strips  135  and  136  mounted on the plastic sheet  110 . 
     The roller  140  is provided with a magnetic strip (not shown) extending along its length. The magnetic strip on the roller  140  makes an air-tight seal with a threshold magnetic strip  138  when the rollable door  150  is fully unrolled. The threshold magnetic strip  138  is connected to the plastic sheet wall  110  and extends horizontally across the bottom of the doorway  120 . 
     The roller door system  100  is further provided with a hydraulic power system which comprises left and right side collapsible hoses  165  and  166  mounted on the external surface of the rollable door  150  and aligned adjacent the left and right side magnetic strips of spring steel  155  and  156 . As shown in  FIGS. 1 and 2 , these strips of spring steel  155  or  156  (see  FIG. 1 ), or strips  255  or  256  of spring steel (see  FIG. 2 ), may be rollable ribbons, functioning at least in part as springs. The left and right side collapsible hoses  165  and  166  are connected to a hydraulic pumping station  160  via a master hose  161  and a splitter  163 . The pumping station  160  includes a hydraulic fluid reservoir and a pump. In this embodiment the hydraulic fluid is water. 
     A rolled ribbon of spring steel (not shown), such that the spring is relaxed when it is fully rolled up, is inserted in each of collapsible hoses  165  and  166 . The balance between the magnetic force exerted by the magnetic strips and the spring constant of the spring steel is carefully designed to ensure that the equilibrium state of the rollable door  150  is its rolled up, raised configuration, however, for safety reasons it is important to ensure that the rollable door  150  does not rewind too quickly when released from its unrolled, lowered configuration. Therefore, in the absence of any other forces acting upon the rollable door  150 , the left and right side ribbons of spring steel will cause the rollable door  150  to roll up around the roller  140  moving the roller  140  to its raised position adjacent the top side  112  of the doorway  120 , thereby maintaining an open doorway  120 . 
       FIG. 2  and  FIG. 3  show an alternative embodiment of a roller door system  200 . Wall  210  made from a flexible plastic sheet material has an opening with a left side  211 , a top side  212 , and a right side  213  which together define a doorway  220 .  FIG. 2  also shows the external view of the roller door system. 
     The roller door system  200  comprises a rollable door  250  and a roller  240 , the roller  240  being attached to the bottom portion of the rollable door  250 . A top portion  252  of the rollable door  250  is permanently or semi-permanently attached to the plastic sheet wall  210  along the top side  212  of the doorway  220 . The rollable door  250  is wider than the doorway  220  and is arranged to overlap the left and right sides  211  and  213  of the doorway  220  on the outer surface of plastic sheet wall  210 . 
     The roller  240  is aligned horizontally across the doorway  220 , and is used for rolling and unrolling the rollable door  250  about the roller  240  to respectively open and close the doorway  220 . Since the top portion  252  of the rollable door is permanently attached to the plastic sheet wall  210  along the top side  212  of the doorway  220 , rolling and unrolling the roller  240  causes it to be translated up and down the doorway  220  respectively. 
     The roller door system  200  further comprises left and right side magnetic strips  235  and  236  that are aligned along the left and right sides  211  and  213  of the doorway  220  respectively and that are mounted on the plastic sheet wall  210 . Corresponding left and right side magnetic strips  255  and  256  are aligned and mounted along left and right sides of the rollable door  250 . As the rollable door  250  is unrolled from the roller  240 , the magnetic strips  255  and  256  mounted on the rollable door  250  are attracted to and make an air-tight seal with the magnetic strips  235  and  236  mounted on the plastic sheet  210 . 
     The roller  240  is provided with a magnetic strip (not shown) extending along its length. The magnetic strip on the roller  240  makes an air-tight seal with a threshold magnetic strip  238  when the rollable door  250  is fully unrolled. The threshold magnetic strip  238  is connected to the plastic sheet wall  210  and extends horizontally across the bottom of the doorway  220 . 
     The roller door system  200  is further provided with a hydraulic power system which comprises left and right side collapsible hoses  265  and  266  mounted on the external surface of the rollable door  250  and aligned adjacent the left and right side magnetic strips of spring steel  255  and  256 . The left and right side collapsible hoses  265  and  266  are connected to a hydraulic pumping station  260  via a master hose  261  and a splitter  263 . The pumping station  260  includes a hydraulic fluid reservoir and a pump. In this embodiment the hydraulic fluid is water. 
     A rolled ribbon of spring steel (not shown), such that the spring is relaxed when it is fully rolled up, is inserted in each of collapsible hoses  265  and  266 . The balance between the magnetic force exerted by the magnetic strips and the spring constant of the spring steel is carefully designed to ensure that the equilibrium state of the rollable door  250  is its rolled up, raised configuration, however, for safety reasons it is important to ensure that the rollable door  250  does not rewind too quickly when released from its unrolled, lowered configuration. Therefore, in the absence of any other forces acting upon the rollable door  250 , the left and right side ribbons of spring steel will cause the rollable door  250  to roll up around the roller  240  moving the roller  240  to its raised position adjacent the top side  212  of the doorway  220 , thereby maintaining an open doorway  220 . 
     The roller  240  is provided with a tether such as an extension shaft  295 ,  296  and a toggle such as a roller bearing  285 ,  286  at each of its ends. The roller bearings  285 ,  286  are designed to cooperate with guide channels  275 ,  276  provided in the wall  210  parallel to the sides of the doorway. Roller bearings  285 ,  286  slide freely within the guide channels  275 ,  276  as the roller  240  moves up and down the doorway. This ensures that the door  250  remains correctly aligned with respect to the magnetic strips  235 ,  236  at all times. Furthermore, this tether system provides additional support and strength to the roller door which is particularly advantageous in situations in which an overpressure is maintained within the structure. 
       FIG. 3  shows a plan view of the roller door system of the second embodiment (the pressurised fluid system not being shown). 
     In use the rolling and unrolling of the door is controlled by how much water the pumping station  160 ,  260  pumps into the collapsible hoses  165 ,  265  and  166 ,  266 . Pumping water into the collapsible hoses  165 ,  265  and  166 ,  266  overcomes the bias of the spring steel causing the rollable door  150 ,  250  to unroll and move the roller  140 ,  240  in a downwards direction across the doorway  120 ,  220 . As the rollable door  150 ,  250  is unrolled from roller  140 ,  240  the magnetic strips  155 ,  255  and  156 ,  256  mounted on the rollable door  150 ,  250  are attracted to and make an air-tight seal with the magnetic strips  135 ,  235  and  136 ,  236  mounted on the flexible shelter wall  110 ,  210 . 
     The hydraulic pressure in the collapsible hoses can be maintained by means of a valve (not shown) in the hydraulic system. This means that the pump does not have to operate continuously once the door is closed. The valve is opened, thereby releasing the hydraulic pressure, when the door is about to be opened. 
     When the pumping station  160 ,  260  pumps water out of the collapsible hoses  165 ,  265  and  166 ,  266  the bias of the spring steel causes the rollable door  150 ,  250  to roll up around the roller  140 ,  240 , thereby separating the magnetic strips  135 ,  136  or  235 ,  236  and corresponding magnetic strips  155 ,  156  or  255 ,  256  from one another breaking the magnetic seals as it does so, and moving the roller  140 ,  240  to its raised position adjacent the top side  112 ,  212  of the doorway  120 ,  220 , thereby opening the doorway  120 ,  220 . 
     When the doorway  120 ,  220  is closed by the rollable door  150 ,  250  and a person requires a fast exit from the shelter, the person may push against the rollable door  150 ,  250  to separate the magnetic strips  135 ,  136  or  235 ,  236  and corresponding magnetic strips  155 ,  156  or  255 ,  256  from one another, to open the doorway without raising the roller. 
     Further embodiments falling within the scope of the appended claims will also be apparent to those skilled in the art. For example although the door system has been described in relation to a temporary emergency shelter, the door system may also find use in other applications such as tent  500 .