Abstract:
A fire suppression system according to an exemplary aspect of the present disclosure includes, among other things, a high pressure inert gas source configured to provide a first inert gas output and a low pressure inert gas source configured to provide a second inert gas output. A distribution network is connected with the high pressure inert gas source and the low pressure inert gas source to distribute the first inert gas output and the second inert gas output throughout a confined space. A volume reduction system is positioned within the confined space and includes a seal member. The seal member is selectively deployable between a first position and a second position to isolate a first volume of the confined space from a second volume of the confined space and reduce an amount of the first inert gas output and the second inert gas output required to respond to a fire threat within the confined space.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional of U.S. patent application Ser. No. 12/816,416, which was filed on Jun. 16, 2010. 
    
    
     BACKGROUND OF THE INVENTION 
     This disclosure relates to a fire suppression system, and more particularly to a fire suppression system having a volume reduction system. 
     Fire suppression systems are often used in aircraft, buildings or other structures having confined spaces. Some fire suppression systems utilize halogenated fire suppressants, such as halons. However, halogens are believed to play a role in ozone depletion of the atmosphere. 
     Fire suppression systems have been proposed that utilize onboard inert gas generating systems (OBIGGS), in combination with stored inert gas, which utilize more environmental friendly fire suppressant agents. Space and weight limitations have limited the ability to incorporate onboard inert gas generating fire suppressant systems in a cost effective manner, particularly in aviation applications. For example, many aircraft include cargo bays having open or slotted floors that effectively make the aircraft bilge part of the cargo bay. Therefore, the volume of agent required to suppress a fire is increased, sometimes by as much as 20%. In addition, the amount of airflow leakage that occurs within the cargo bay further increases the amount of agent required to suppress a fire threat. 
     SUMMARY 
     A fire suppression system according to an exemplary aspect of the present disclosure includes, among other things, a high pressure inert gas source configured to provide a first inert gas output and a low pressure inert gas source configured to provide a second inert gas output. A distribution network is connected with the high pressure inert gas source and the low pressure inert gas source to distribute the first inert gas output and the second inert gas output throughout a confined space. A volume reduction system is positioned within the confined space and includes a seal member. The seal member is selectively deployable between a first position and a second position to isolate a first volume of the confined space from a second volume of the confined space and reduce an amount of the first inert gas output and the second inert gas output required to respond to a fire threat within the confined space. 
     In a further non-limiting embodiment of the foregoing fire suppression system, the first volume includes an aircraft cargo bay and the second volume includes a bilge. A floor having at least one opening extends between the aircraft cargo bay and the bilge. 
     In a further non-limiting embodiment of either of the foregoing fire suppression systems, the seal member obstructs the at least one opening in the second position. 
     In a further non-limiting embodiment of any of the foregoing fire suppression systems, the seal member is mounted to a beam structure of the floor with a restraint member. 
     In a further non-limiting embodiment of any of the foregoing fire suppression systems, the confined space includes a cheek, and the volume reduction system includes a leakage reduction system that blocks airflow from the first volume and the second volume into the cheek. 
     In a further non-limiting embodiment of any of the foregoing fire suppression systems, the leakage reduction system includes an inflatable seal member. 
     The various features and advantages of this disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an example fire suppression system. 
         FIG. 2  illustrates an example volume reduction system for use with a fire suppression system. 
         FIG. 3  illustrates another example volume reduction system for use with a fire suppression system. 
         FIG. 4  illustrates another example volume reduction system for use with a fire suppression system. 
         FIG. 5  illustrates yet another example volume reduction system for use with a fire suppression system. 
         FIG. 6  illustrates an example leakage reduction system for use with a fire suppression system. 
         FIG. 7  illustrates another example leakage reduction system for use with a fire suppression system. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates selected portions of an example fire suppression system  10  that may be used to control a fire threat. The fire suppression system  10  may be utilized with an aircraft  12  (shown schematically); however, it is to be understood that the exemplary fire suppression system  10  may alternatively be utilized in other types of structures. 
     In this example, the fire suppression system  10  is implemented within the aircraft  12  to control any fire threats that may occur in confined spaces  14   a  and  14   b . For instance, the confined spaces  14   a  and  14   b  may be cargo bays, electronic bays, wheel wells or other confined spaces where fire suppression is desired. The fire suppression system  10  includes a high pressure inert gas source  16  for providing a first inert gas output  18 , and a low pressure inert gas source  20  for providing a second inert gas output  22 . For example, the high pressure inert gas source  16  provides the first inert gas output  18  at a higher mass flow rate than the second inert gas output  22  from the low pressure inert gas source  20 . 
     The high pressure inert gas source  16  and the low pressure inert gas source  20  are connected to a distribution network  24  that distributes the first and second inert gas outputs  18 ,  22 . In this case, the first and second inert gas outputs  18 ,  22  may be distributed to the confined space  14   a , confined space  14   b , or both, depending upon where a fire threat is detected. As may be appreciated, the aircraft  12  may include additional confined spaces that are also connected within the distribution network  24  such that the first and second insert gas outputs  18  and  22  may be distributed to any or all of the confined spaces. 
     The fire suppression system  10  also includes a controller  26  that is operatively connected with at least the distribution network  24  to control how the respective first and second inert gas outputs  18  and  22  are distributed through the distribution network  24 . The controller  26  may include hardware, software, or both. For instance, the controller  26  may control whether the first inert gas output  18  and/or the second inert gas output  22  are distributed to the confined spaces  14   a ,  14   b  and at what mass and mass flow rate the first inert gas output  18  and/or the second inert gas output  22  are distributed. 
     The controller  26  of the fire suppression system  10  may be in communication with other onboard controllers or warning systems  27  such as a main controller or multiple distributed controllers of the aircraft  12 , and a controller (not shown) of the low pressure inert gas source  20 . For instance, the other controllers or warning systems  27  may be in communication with other systems of the aircraft  12 , including a fire threat detection system for detecting a fire within the confined spaces  14   a ,  14   b  and issuing a fire threat signal in response to a detected fire threat. In another example, the warning systems  27  include their own sensors for detecting a fire threat within confined spaces  14   a ,  14   b  of the aircraft  12 . 
     As an example, the controller  26  may initially cause the release of the first inert gas output  18  within the confined space  14   a  in response to a fire threat signal from the warning systems  27  to reduce an oxygen concentration within the confined space  14   a  below a predetermined threshold. The controller  26  may cause the release of the second inert gas output  22  to the confined space  14   a  to facilitate maintaining the oxygen concentration below the predetermined threshold. In one example, the predetermined threshold may be less than a 13% oxygen concentration level, such as 12% oxygen concentration, within the confined space  14   a . The threshold may also be represented as a range, such as 11.5% to 12%. A premise of setting the threshold below 12% is that ignition of aerosol substances, which may be found in passenger cargo in a cargo bay, is limited (or in some cases prevented) below a 12% oxygen concentration. As an example, the threshold may be established based on cold discharge (i.e., no fire case) of the first and second inert gas outputs  18 ,  20  in an empty cargo bay with the aircraft  12  grounded and at sea level air pressure. 
     In this example, the high pressure inert gas source  16  is a pressurized inert gas source. The high pressure inert gas source  16  may include a plurality of storage tanks  28   a - 28   d . The tanks may be made of lightweight materials to reduce the weight of the aircraft  12 . Although four storage tanks  28   a - 28   d  are shown, it is to be understood that additional storage tanks or fewer storage tanks may be used in other implementations. The number of storage tanks  28   a - 28   d  may depend on the sizes of the confined space  14   a , the confined space  14   b  (or other confined spaces), leakage rates of the confined spaces, ETOPS (Extended-range Twin-engine Operational Performance Standards) times, or other factors. Each of the storage tanks  28   a - 28   d  holds pressurized inert gas, such as nitrogen, helium, argon or a mixture thereof. The inert gas may also include trace amounts of other gases, such as carbon dioxide. 
     The low pressure inert gas source  20  may be a known onboard inert gas generating system (e.g., “OBIGGS”) for providing a flow of inert gas, such as nitrogen enriched air, to the aircraft  12 . Nitrogen enriched air includes a higher concentration of nitrogen than ambient air. In general, the low pressure inert gas source  20  receives input air, such as compressed air from a compressor stage of a gas turbine engine of the aircraft  12  or air from one of the confined spaces  14   a ,  14   b  that is compressed by an ancillary compressor, and separates the nitrogen from the oxygen in the input air to provide an output that is enriched in nitrogen compared to the input air. The output nitrogen enriched air may be used as the second inert gas output  22 . The low pressure inert gas source  20  may also utilize input air from a second source, such as cheek air, secondary compressor air from a cargo bay, etc., which may be used to increase capacity on demand. As an example, the low pressure inert gas source  20  may be similar to the systems described in U.S. Pat. No. 7,273,507 or U.S. Pat. No. 7,509,968 but are not specifically limited thereto. 
     The example fire suppression system  10  further includes a volume reduction system  30  positioned within one or more of the confined spaces  14   a ,  14   b . The volume reduction system  30  generally isolates a first volume  32  of the confined spaces  14   a ,  14   b  from a second volume  34  of the confined spaces  14   a ,  14   b . A leakage reduction system  36  may also be positioned within one or more of the confined spaces  14   a ,  14   b  for reducing an airflow leakage of the confined spaces  14   a  and  14   b . As may be appreciated, the fire suppression system  10  can include only the volume reduction system  30 , only the leakage reduction system  36 , or both systems. 
       FIG. 2  illustrates an example volume reduction system  30  positioned within a confined space  114 . In this disclosure, like reference numerals designate like elements where appropriate, and reference numerals with the addition of 100 designate modified elements. The modified elements may incorporate the same features and benefits of the corresponding original elements and vice versa. The fire suppression system  10  including the volume reduction system  30  is implemented in a confined space  114  of an aircraft  12 , but may alternatively be implemented in other types of structures. 
     In this example, the confined space  114  is a cargo bay of an aircraft. The confined space  114  includes a floor  38  that separates the confined space  114  between a first volume  132  (e.g., a cargo bay volume) and a second volume  134  (e.g., a bilge volume). The floor  38  includes a plurality of horizontally disposed beam structures  46  that extend across the confined space  114 . On some aircraft, the floor  38  is not sealed and allows communication of the cargo bay atmosphere with the bilge atmosphere. In this example, the floor  38  includes a slotted floor having a plurality of openings  42  that allow communication of the cargo bay atmosphere with the bilge atmosphere. 
     The volume reduction system  30  is positioned within the confined space  114  to isolate the first volume  132  from the second volume  134  during a fire threat to limit cargo bay volume and minimize the amount of inert gas required from both inert gas sources  16 ,  20  to respond to a fire threat. In this example, the volume reduction system  30  includes seal members  40  that are deployable to seal off the openings  42  of the floor  38 . As may be appreciated, the floor  38  may include a plurality of floor openings  42 , and at least one seal member  40  could be positioned relative to each opening  42  to seal the opening  42  during a fire threat. 
     In this example, the seal members  40  include inflatable tubes or airbags. In response to detection of a fire threat, the seal members  40  are deployed from a first, deflated position X (shown in phantom lines) to a second, inflated position X′ to seal or substantially close off the openings  42  of the floor  38 . The seal members  40  are inflated via a gas source  44 . In one example, the gas source  44  is provided by the high pressure inert gas source  16  of  FIG. 1 . In another example, the gas source  44  of the volume reduction system  30  includes a dedicated stored gas bottle, gas generator, or gas generator air aspirator that can be used to inflate the seal members  40  and respond to a fire threat. 
     The volume reduction system  30  communicates with the controller  26  to respond to a fire threat signal communicated from the warning systems  27 . Once the fire threat signal is received, the controller  26  commands the volume reduction system  30  to deploy the seal members  40 , such as by inflating the tubes, to seal the openings  42  of the floor  38 . 
     The seal member  40  includes a fire resistant material. One example fire resistant material is NOMEX®, a DuPont product. As may be appreciated, the seal members could include any fire resistant material. 
     The seal members  40  of the volume reduction system  30  are positioned relative to the floor  38  of the confined space  114 . In this example, the seal members  40  are attached to an underside  37  of the floor  38 . The seal members  40  extend longitudinally (into the page) between each beam structure  46  of the floor  38 . The seal members  40  are attached relative to the floor  38  with a restraint member  48 . The restraint member  48  may include a strap, band, netting, adhesive, clamp or any other suitable restraint that prevents displacement of the seal members  40  downwardly into the second volume  134  (i.e., the bilge). 
       FIG. 3  illustrates another example volume reduction system  230  positioned within a confined space  214 . The confined space  214  includes a floor  238  having a plurality of openings  242 . In this example, the floor  238  is a grilled floor. 
     The volume reduction system  230  includes a plurality of seal members  240 . In this example, the seal members  240  are inflatable bags or mats that are made of a fire resistant material and that are deployable to seal or substantially close off the openings  242  of the floor  238 . The seal members  240  are deployable between a first position X (shown in phantom lines) and a second position X′ to seal the openings  242 , and therefore isolate a first volume  232  from a second volume  234  to reduce the amount of agent required to respond to a fire threat within the confined space  214 . A restraint member  48  attaches the seal members  240  relative to the floor  238 . 
     The volume reduction system  230  communicates with the controller  26  to respond to a fire threat signal communicated from a warning system  27 . Once the fire threat signal is received, the controller  26  commands the volume reduction system  230  to deploy the seal members  240 , such as by inflating the bags or mats with the gas source  44 , to seal the openings  242  of the floor  238 . 
       FIG. 4  illustrates another example volume reduction system  330  positioned within a confined space  314 . In this example, the confined space  314  includes a floor  338  having a grilled floor structure that includes a plurality of openings  342 . A seal member  340  is deployable to seal the openings  342  and isolate a first volume  332  from a second volume  334  of the confined space  314 . 
     In this example, the seal member  340  includes a roller screen assembly  350 . The roller screen assembly  350  includes a screen storage housing  352 , an actuator motor  354 , a sealed guide track  356  that extends between the screen storage housing  352  and the actuator motor  354 , a pull device  355  and a roller screen  358  made of a fire resistant material. In response to a fire threat, the folded roller screen  358  is deployed from the storage housing  352  (first position X) and is unrolled via the pull device  355  along the sealed guide track  356  by the actuator motor  354  (second position X′) to seal the openings  342  of the floor  338  and reduce the amount of agent required to respond to a fire threat within the confined space  314 . The pull device  355  can include a cable, piston actuators, gear drives or other suitable pulling devices. In this example, the roller screen assembly  350  is mounted to an underside  337  of the floor  338  in a known manner. 
     The volume reduction system  330  communicates with the controller  26  to respond to a fire threat signal communicated from a warning system  27 . Once the fire threat signal is received, the controller  26  commands the volume reduction system  330  to deploy the seal member  340 , such as by unrolling the roller screen  358  via the actuator motor  354 , to seal the openings  342  of the floor  338 . The volume reduction system  330  cooperates with the controller  26  to seal off the first volume  332  from the second volume  334 , thus minimizing the amount of inert gas required to respond to the fire threat signal. 
       FIG. 5  illustrates another example volume reduction system  430  positioned within a confined space  414 . The confined space  414  includes a floor  438  having a plurality of openings  442 . In this example, the floor  438  includes a slotted floor structure. The example volume reduction system  430  includes a plurality of seal members  440  that are deployable to seal the floor openings  442  to isolate a first volume  432  from a second volume  434  of the confined space  414 . 
     In this example, the seal members  440  include a sliding door panel assembly  460 . In this example, the sliding door panel assembly  460  is mounted to an underside  437  of the floor  438  in a known manner. The sliding door panel assembly  460  includes a sliding door panel  462 , a sealed guide track  464 , a pull device  466  and a cable actuator motor  468 . In response to a fire threat in the confined space  414 , the actuator motor  468  begins pulling the pull device  466 . The pull device  466  can include a cable, piston actuators, gear drives or other suitable pulling devices. The pull device  466  is connected to the sliding door panel  462 , which pulls the slider door panel  462  between a first, stowed position X (shown in phantom lines) and a second, deployed position X′ along the sealed guide track  464 . In the deployed position, the sliding door panel  462  seals the openings  442  of the floor  438  to substantially isolate the first volume  432  from the second volume  434  of the confined space  414 . 
     The volume reduction system  430  communicates with the controller  26  to respond to a fire threat signal communicated from a warning system  27 . Once the fire threat signal is received, the controller  26  commands the volume reduction system  430  to deploy the seal members  440 , such as by closing the sliding door panels  462 , to seal the openings  442  of the floor  438 . 
       FIG. 6  illustrates an example leakage reduction system  536  for reducing airflow leakage of the confined space  514 . The leakage reduction system  536  may be used either apart from or in combination with any of the example volume reduction systems  30 ,  230 ,  330 , or  430 . The confined space  514  includes a cheek  570 . The cheek  570  is a compartment external to the cargo bay of an aircraft  12  but internal to the aircraft  12  skin. An outflow valve  572  limits the differential pressure between the interior of the aircraft and the exterior environment, and therefore impacts the differential pressure between the cargo bay/bilge volumes and the cheek volume. 
     Airflow from a first volume  532  (the cargo bay) and a second volume  534  (the bilge) of the confined space  514  may escape from the confined space  514  into the cheek  570 . Airflow leakage can increase the amount of agent required to maintain the oxygen concentration of the confined space  514  below a predetermined threshold. Accordingly, the fire suppression system  10  can include the leakage reduction system  536  having a seal member  574  that is deployable to block and/or reduce airflow lockage within the confined space  514 . 
     The seal member  574  can include an inflatable tube, airbag, mat or any other fire resistant seal member that is inflatable to reduce the amount of airflow leakage between the cargo bay  532 , bilge  534  and cheek  570  of the confined space  514 . In one example, the seal members  574  are positioned between portions of the beam structures  546  of the floor  538  of the confined space  514  that are adjacent to the cheek  570 . In another example, the seal members  574  are mounted within the cheek  570  (See  FIG. 7 ). As may be appreciated, at least one seal member  574  may be positioned at any known area of airflow leakage within the confined space  514 . 
     The seal member  574  are deployable between a first position X (shown in phantom lines) and a second position X′ to substantially seal the cheek  570  from the first volume  532  and/or the second volume  534  of the confined space  514 . As may be appreciated, the leakage reduction system  536  may employ a plurality of seal members  574  for accomplishing the reduction in airflow leakage. 
     The seal members  574  are inflated via a gas source  544 . The gas source  544  may be provided by the high pressure inert gas source  16  of  FIG. 1 , a dedicated stored gas bottle, gas generator, gas generator air aspirator or other suitable gas source. 
     A restraint member  548  maintains a desired positioning of the seal members  574  of the leakage reduction system  536 . The restraint member  548  includes straps, bands, netting, adhesives, clamps or any other suitable restraint member. 
     The leakage reduction system  536  communicates with the controller  26  to respond to a fire threat signal communicated from a warning system  27 . Once the fire threat signal is received, the controller  26  commands the leakage reduction system  536  to deploy the seal members  574 , such as by inflating the tubes with the gas source  44 , to seal the cheek  570 . 
     The foregoing description shall be interpreted as illustrative and not in any limiting sense. A worker of ordinary skill in the art would understand that certain modifications could come within the scope of this disclosure. For these reasons, the following claims should be studied to determine the true scope and content of this disclosure.