Abstract:
An automotive vehicle includes a vehicle body and at lease one reservoir containing a fire suppressant agent. A distribution system receives the fire suppression agent from the reservoir and conducts the agent to at least one location about the vehicle&#39;s body in response to the determination by a sensor system and controller that the vehicle has been subjected to a significant impact. The reservoir includes a multifunction valve element which controls pressure and vacuum within the reservoir during standby operation, while causing the fire suppressant agent to be directed through the distribution system if the propellant activates.

Description:
RELATED APPLICATIONS  
       [0001]     This application is a continuation-in-part of U.S. patent application Ser. No. 10/907,134, filed Mar. 22, 2005. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to an automotive vehicle having an onboard apparatus for suppressing a vehicle fire.  
         [0004]     2. Disclosure Information  
         [0005]     Police vehicles are subject to increased exposure to collisions, particularly high-speed rear-end collisions, arising from the need for police officers to stop on the shoulders, or even in the traffic lanes, of busy highways. Unfortunately, other motorists are known to collide with police vehicles employed in this manner. These accidents can compromise the fuel system on any vehicle and may cause fires. The present system is designed to suppress the spread of, or potentially, to extinguish such a fire. U.S. Pat. No. 5,590,718 discloses an anti-fire system for vehicles in which a number of fixed nozzles are furnished with a fire extinguishing agent in response to an impact sensor. The system of the&#39;718 patent suffers from a problem in that the fixed nozzles are not suited to the delivery of the extinguishing agent at ground level. Also, the &#39;718 patent uses a valving system which could become clogged and therefore inoperable. U.S. Pat. No. 5,762,145 discloses a fuel tank fire protection device including a powdered extinguishing agent panel attached to the fuel tank. In general, powder delivery systems are designed to prevent ignition of fires and are deployed upon impact. As a result, the powder may not be able to follow the post-impact movement of the struck vehicle and may not be able to prevent the delayed ignition or re-ignition of a fire.  
         [0006]     The present fire suppression system provides significant advantages, as compared with prior art vehicular fire suppression systems.  
       SUMMARY OF THE INVENTION  
       [0007]     According to an aspect of the present invention, an onboard fire suppression system includes at least one reservoir containing a fire suppressant agent, and a propellant, operatively associated with the reservoir, for expelling the fire suppressant agent from the reservoir under pressure. A distribution system receives fire suppression agent expelled from the reservoir and distributes it to at least one location. A multi-function control valve, operatively connected with the reservoir, maintains pressure within the reservoir within a predetermined range during standby operation, with the control valve closing in the event that the propellant is activated. The multi-function control valve includes a vacuum responsive element, a standby pressure relief element, and a high flow closure element. This control valve extends through a wall of the reservoir.  
         [0008]     The valving functions of a multifunction control valve according to an aspect of the present invention are performed by a vacuum responsive element having an inward-opening poppet, by a standby pressure relief element having an outward-opening poppet, and by an outward-closing poppet which is responsive to high rate flow of the suppressant agent. The outward closing poppet closes in response to elevated suppressant flow rate and elevated suppressant pressure which normally accompanies discharge of the suppressant from the reservoir. The inward-opening poppet opens in the event that the pressure within the reservoir falls below a predetermined minimum pressure. The outward-opening poppet moves to an open position in the event that pressure within the reservoir exceeds a predetermined maximum static pressure, with the high flow-responsive poppet closing in the event that the pressure produced by the propellant exceeds a predetermined maximum dynamic pressure produced by an activated propellant.  
         [0009]     According to another aspect of the present invention, the inward-opening poppet and the outward-opening poppet are resiliently biased into normally-closed positions, with the outward-closing poppet being resiliently biased into a normally-open position.  
         [0010]     According to another aspect of the present invention, a propellant may either be housed within the reservoir or external to the reservoir.  
         [0011]     According to another aspect of the present invention, the multi-function control valve may be contained within a filler port plug for the reservoir.  
         [0012]     It is an advantage of a onboard fire suppression system according to the present invention that pressure changes due to environmental conditions such as changes in altitude and changes in ambient temperature may be accommodated by a fire suppression system reservoir without concomitant material fatigue due to flexing which could otherwise be caused by such changes in pressure.  
         [0013]     Other advantages, as well as features of the present invention will become apparent to the reader of this specification. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  is a ghost perspective view of an automotive vehicle having a fire suppression system according to the present invention.  
         [0015]      FIG. 2  is an exploded perspective view of a portion of a fire suppression system according to the present invention.  
         [0016]      FIG. 3  is a perspective view of a control module used with a system according to the present invention.  
         [0017]      FIG. 4  is a perspective view of a manually activatable switch used with a fire suppression system according to the present invention.  
         [0018]      FIG. 5  illustrates a portion of a wiring harness used with the present system.  
         [0019]      FIG. 6  is a flowchart showing a portion of the logic used to control a system according to the present invention.  
         [0020]      FIG. 7  is a cutaway perspective view of a fire suppression agent reservoir according to one aspect of the present invention.  
         [0021]      FIG. 8  is a perspective view of a variable geometry fire suppression agent nozzle according to one aspect of the present invention.  
         [0022]      FIG. 9  is a block diagram of a fire suppression system and with additional components for occupant restraint according to one aspect of the present invention.  
         [0023]      FIG. 10  is a perspective view of a vehicle having a fire suppression system with a reservoir having a multifunction control valve according to one aspect of the present invention.  
         [0024]      FIG. 11  is a perspective view of a suppression agent reservoir according to one aspect of the present invention.  
         [0025]      FIG. 12  is a sectional view of the reservoir of  FIG. 11 , taken along the line  12 - 12  of  FIG. 11 .  
         [0026]      FIG. 13  is an enlarged view of the control valve shown in  FIG. 12 .  
         [0027]      FIG. 14  is perspective view similar to  FIG. 11 , but illustrating a reservoir teamed with an external propellant. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]     As shown in  FIG. 1 , vehicle  10  has a passenger airbag restraint  48  and a driver&#39;s airbag restraint  50  mounted adjacent steering wheel  52 . A fire suppression system includes controller  66  which is mounted upon floor pan  68  of vehicle  10 , and reservoirs  18  which are mounted under floor pan  68  in the so-called kick-up area adjoining the rear axle of vehicle  10 . Those skilled in the art will appreciate in view of this disclosure that additional passenger restraint devices, such as seat belt pretensioners and side airbags, may be installed in a vehicle and controlled at least in part by, or in conjunction with, controller  66 .  
         [0029]      FIG. 1  shows not only reservoirs  18  but also a portion of right and left side fire suppression conduits  28 , as well as fixed geometry nozzles  30  and variable geometry nozzles  36 . As seen in  FIG. 1 , variable geometry nozzles  36  project downwardly to allow fire suppression agent to be expelled from reservoirs  18  and placed at a low angle to the ground surface the vehicle is operating upon. This mode of operation is possible because variable geometry nozzles  36  are, as shown in  FIG. 2 , telescopingly extensible. This telescoping feature, which is shown in greater detail in  FIG. 8 , is produced by a sliding spray head,  40 , which is slidingly engaged with conduit  28  such that gas pressure within conduit  28  forces spray head  40  downwardly into its extended position, causing fire suppression agent  22  to be discharged through a number of holes  42  formed in spray head  40 . As shown in  FIG. 2 , at least two variable geometry nozzles  36  may be employed with single reservoir  18 , along with at least two fixed nozzles  30  which are spray bars each having a number of orifices  34 . While in their normally closed state, variable geometry nozzles  36  are liquid-tight by virtue of seals  46 , which are interposed between an end of each of spray heads  40  and the corresponding ends of conduits  28 . In a preferred embodiment, seals  46  comprise elastomeric boots attached to an outer surface of conduit  28 . Seals  46  are simply sheared by the deploying spray head  40  when the present system is discharged. Fixed nozzles  30  are also rendered liquid-tight by covers  44 , which are simply blown off when the present system is discharged. The sealing of nozzles  30  and  36  is important, because this prevents the ingress of road splash, which could block the system in sub-freezing weather or cause corrosion or blockage due to mud or other foreign matter.  
         [0030]     Additional details of reservoir  18  are shown in  FIG. 7 . Tank  90  contains approximately 1.5 L of fire suppression agent  22 , and a propellant  92 . Propellant  92  includes two squibs (not shown) which are activated simultaneously by controller  66  via lines  91  so as to release a large amount of gas, forcing fire suppressant agent  22  from tank  90  and into distribution system  26 , including conduit  28  and the various fixed and variable geometry nozzles. A preferred propellant, marketed by Primex Aerospace Company as model FS01-40, is a mixture including aminotetrazole, strontium nitrate, and magnesium carbonate. This is described in U.S. Pat. No. 6,702,033, which is hereby incorporated by reference into this specification.  
         [0031]     Those skilled in the art will appreciate in view of this disclosure that other types of propellants could be used in the present system, such as compressed gas canisters and other types of pyrotechnic and chemical devices capable of creating a gas pressure force in a vanishingly small amount of time. Moreover, fire suppressant agent  22 , which preferably includes a water-based solution with hydrocarbon surfactants, fluorosurfactants, and organic and inorganic salts sold under the trade name LVS Wet Chemical Agent® by Ansul Incorporated, could comprise other types of agents such as powders or other liquids, or yet other agents known to those skilled in the art and suggested by this disclosure. If two reservoirs  18  are employed with a vehicle, as is shown in  FIG. 1 , all four squibs will be deployed simultaneously.  
         [0032]      FIG. 4  shows manually activatable switch  54  for use with the present system. As shown in  FIG. 1 , switch  54  may be advantageously located on the headliner of vehicle  10  between the sun visors, or at any other convenient position. To use this switch  54 , hinged clear cover  56  is first opened by pressing on cover  56 . Thereafter, the fire suppression system may be triggered by manually pressing pushbutton  58 . If the vehicle occupants are not disposed to release cover  56 , the system may be triggered by merely sharply depressing cover  56 , thereby closing contacts (not shown) contained within platform  60 .  
         [0033]     Because the present system is intended for use when the vehicle has received a severe impact, controller  66 , which is shown in  FIG. 3 , contains a redundant power reserve or supply, which allows operation of the fire suppression system for about nine seconds, even if controller  66  becomes isolated from the vehicle&#39;s electrical power supply. Wiring harness  80 , as shown in  FIG. 5 , is armored, and has a para-aramid fiber inner sheath,  82 , of about 2 mm in thickness, which helps to shield the conductors within harness  80  from abrasion and cutting during a vehicle impact event. This para-ramid fiber is sold under the trade name KEVLAR® by the DuPont Company. This armoring helps to assure that communication between controller  66  and reservoirs  18  remains in effect during an impact event. Post-impact communications are further aided by redundancy in the control system. Specifically, four independent sets of primary conductors,  79   a - d , extend from controller  66  to reservoirs  18  protected by sheath  82 . Moreover, an H-conductor, shown at  81  in  FIG. 5 , extends between reservoirs  18 . Thus, if one or both of the primary conductors  79   a - b , or  79   c - d , extending to one of reservoirs  18  should become severed, H-conductor  81  will be available to carry the initiation signal from the undamaged lines to both of reservoirs  18 .  
         [0034]     As noted above, an important feature of the present invention resides in the fact that the control parameters include not only vehicle impact, as measured by an accelerometer such as that shown at  70  in  FIG. 9 , but also vehicle speed, as measured by means of speed sensors  74 , also shown in  FIG. 9 . Speed sensors  74  may advantageously be existing sensors used with an anti-lock braking system or vehicle stability system. Alternatively, speed sensors  74  could comprise a global positioning sensor or a radar or optically based ground-sensing system. Accelerometer  70 , as noted above, could be used with a conventional occupant restraint airbag system, thereby maximizing use of existing systems within the vehicle. Advantageously, accelerometer  70  may be an amalgam of two or more accelerometers having differing sensing ranges. Such arrangements are known to those skilled in the art and suggested by this disclosure. At least a portion of the various sensors could either be integrated in controller  66  or distributed about vehicle  10 .  
         [0035]      FIG. 6  shows a sequence which is used according to one aspect of the present invention for activating a release of fire suppressant agent.  
         [0036]     Beginning at block  100 , controller  66  performs various diagnostics on the present system, which are similar to the diagnostics currently employed with supplemental restraint systems. For example, various sensor values and system resistances will be evaluated on a continuous basis. Controller  66  periodically moves to block  102 , wherein the control algorithm will be shifted from a standby mode to an awake mode in the event that a vehicle acceleration, or, in other words, an impact, having a magnitude in excess of a relatively low threshold is sensed by accelerometer  70 . Also, at block  102  a backup timer will be started. If the algorithm is awakened at block  102 , controller  66  disables manually activatable switch  54  at block  104  for a predetermined amount of time, say 150 milliseconds. This serves to prevent switch  54  from inadvertently causing an out-of-sequence release of fire suppression agent. Note that at block  104 , a decision has not yet been made to deploy fire suppression agent  22  as a result of a significant impact.  
         [0037]     At block  106 , controller  66  uses output from accelerometer  70  to determine whether there has been an impact upon vehicle  10  having a severity in excess of a predetermined threshold impact value. Such an impact may be termed a significant, or “trigger”, impact. If an impact is less severe than a trigger impact, the answer at block  106  is “no”, and controller  66  will move to block  105 , wherein an inquiry is made regarding the continuing nature of the impact event. If the event has ended, the routine moves to block  100  and continues with the diagnostics. If the event is proceeding, the answer at block  105  is “yes”, and the routine loops to block  106 .  
         [0038]     If a significant impact is sensed by the sensor system including accelerometer  70  and controller  66 , the answer at block  106  will be “yes.” If such is the case, controller  66  moves to block  108  wherein the status of a backup timer is checked. This timer was started at block  102 .  
         [0039]     Once the timer within controller  66  has counted up to a predetermined, calibratable time on the order of, for example, 5-6 seconds, controller  66  will cause propellant  92  to initiate delivery of fire suppressant agent  22 , provided the agent was not released earlier. Propellant  92  is activated by firing an electrical squib so as to initiate combustion of a pyrotechnic charge. Alternatively, a squib may be used to pierce, or otherwise breach, a pressure vessel. Those skilled in the art will appreciate in view of this disclosure that several additional means are available for generating the gas required to expel fire suppressant agent  22  from tank  90 . Such detail is beyond the scope of this invention. An important redundancy is supplied by having two squibs located within each of tanks  90 . All four squibs are energized simultaneously.  
         [0040]     The velocity of the vehicle  10  is measured at block  110  using speed sensors  74 , and compared with a low velocity threshold. In essence, controller  66  processes the signals from the various wheel speed sensors  74  by entering the greatest absolute value of the several wheel speeds into a register. This register contains both a weighted count of the number of samples below a threshold and a count of the number of samples above the threshold. When the register value crosses a threshold value, the answer at block  110  becomes “yes.” In general, the present inventors have determined that it is desirable to deploy fire suppression agent  22  prior to the vehicle coming to a stop. For example, fire suppression agent  22  could be dispersed when the vehicle slows below about 15 kph.  
         [0041]     At block  112 , controller  66  enters a measured vehicle acceleration value into a second register. Thereafter, once the acceleration register value decays below a predetermined low g threshold, the answer becomes “yes” at block  112 , and the routine moves to block  114  and releases fire suppressant agent  22 . In essence, a sensor fusion method combines all available sensor information to verify that the vehicle is approaching a halt. The routine ends at block  116 . Because the present fire suppression system uses all of the available fire suppression agent  22  in a single deployment, the system cannot be redeployed without replacing at least reservoirs  18 .  
         [0042]      FIG. 6  does not include the activation of occupant restraints  48  and  50 , it being understood that known control sequences, having much different timing constraints, may be employed for this purpose. In point of contrast, the low velocity threshold allows the present system to deliver the fire suppression agent while the vehicle is still moving, albeit at a very low velocity. This prevents the rear wheels of the vehicle from shadowing, or blocking dispersion of fire suppressant agent  22 . Also, in many cases, a vehicular fire may not become well-established until the vehicle comes to a halt.  
         [0043]     As shown in  FIG. 10 , vehicle  200  has controller  204  for operating an onboard fire suppression system. As shown in  FIG. 11 , a supply of fire suppression agent  206  is contained within reservoirs  208 , with only one reservoir  208  being shown. Propellant  210  provides energy for forcing agent  206  from reservoir  208  under pressure when so directed by controller  204 .  
         [0044]     Reservoir  208  has a combination fill plug and control valve inserted in an upper wall,  212 . As shown in  FIG. 12 , upper wall  212  has a threaded insert,  216 , mounted therein. In a preferred embodiment, reservoir  208  is formed as fiber-reinforced resin composite, for the purpose of saving weight and avoiding corrosion in a difficult automotive environment.  
         [0045]     As shown in  FIGS. 12 and 13 , control valve  218  is mounted within a valve holder  220 , which is itself threaded into threaded insert  216 . Valve holder  220  has a discharge port,  232 , which allows gases to enter and leave reservoir  208  as described herein.  
         [0046]     Control valve  218  includes three valve elements, with all three valve elements being mounted within valve body  240  which is mounted within valve holder  220 . The first valve element is an inward-opening poppet,  244 , which seats on median bulkhead  248  of outward-opening poppet  254 . Inward-opening poppet  244  cooperates with vacuum orifice  250  ( FIG. 13 ) formed in median bulkhead  248  of outward-opening poppet  254 , to establish a minimum pressure value for the gas within reservoir  208 . In aid of this objective, compression spring  246  urges inward-opening poppet  244  into contact with median bulkhead  248 , so as to prevent gases from leaving reservoir  208 . This is important when propellant  210  functions, because otherwise suppressant agent would be lost through control valve  218 . In essence, inward-opening poppet  244  functions as a vacuum responsive element to maintain minimum pressure within reservoir  208  during standby operation of the present onboard fire suppression system. In so doing, inward-opening poppet  244  prevents undue working, or perhaps even work hardening, of reservoir  208  due as a result of flexure incurred at low pressure resulting from altitude or meteorological changes.  
         [0047]     Outward-opening poppet  254  functions as both a standby pressure relief element having an outwardly-opening poppet, and an outward-closing poppet responsive to high rate flow of suppressant agent  206 . Outward opening poppet  254  is positioned against valve body  240  at sealing surface  254   a , by means of compression spring  258 . When pressure within reservoir  208  rises at a slow rate during standby operation, spring  258  will be compressed and gas or other fluid will be allowed to flow through control passage  242 , past sealing surface  254   a , and then through discharge port  232 . If, however, propellant  210  activates, the high flow of suppressant agent  206  leaving reservoir  208 , which is accompanied by a high dynamic pressure, will cause poppet  254  to move upwardly so as to engage sealing surface  254   b  with upper surface  240   a  of valve body  240 , thereby preventing an outflow of suppressant agent  206  through discharge port  232 . Poppet  254  is thus seen to be a dual-mode poppet functioning as a type of spool valve.  
         [0048]      FIG. 14  shows an externally located propellant,  300 , which preferably comprises a cold gas inflator. Controller  204  operates valve  304  to allow compressed gas within propellant  300  to travel through conduit  308  into reservoir  208 . In this embodiment, multi-function control valve  218  is mounted in a portion of conduit  308 .  
         [0049]     Although the present invention has been described in connection with particular embodiments thereof, it is to be understood that various modifications, alterations, and adaptations may be made by those skilled in the art without departing from the spirit and scope of the invention set forth in the following claims.