as shown in fig1 , 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 . fig1 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 fig1 , 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 fig2 , telescopingly extensible . this telescoping feature , which is shown in greater detail in fig8 , 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 fig2 , 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 . additional details of reservoir 18 are shown in fig7 . 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 . 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 fig1 , all four squibs will be deployed simultaneously . fig4 shows manually activatable switch 54 for use with the present system . as shown in fig1 , 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 . because the present system is intended for use when the vehicle has received a severe impact , controller 66 , which is shown in fig3 , 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 fig5 , 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 - aramid 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 fig5 , 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 . 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 fig9 , but also vehicle speed , as measured by means of speed sensors 74 , also shown in fig9 . 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 . fig6 shows a sequence which is used according to one aspect of the present invention for activating a release of fire suppressant agent . 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 . at block 106 , controller 66 uses output from accelerometer 70 to determine whether there has been an impact upon vehicle 10 having a severity is 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 . 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 . 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 . 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 . 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 . fig6 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 . fig1 and 11 illustrate an additional nozzle embodiment according to another aspect of the present invention . rather than having a stamped and welded construction , nozzle 232 is porous . the porous material may be either ceramic , or sintered metal , or other types of porous materials known to those skilled in the art and suggested by this disclosure . the material may be cast , or pressed , or extruded , or formed by any other suitable method . fig1 shows nozzle body 236 in its stowed position , and fig1 shows nozzle body 236 in its telescopically deployed position , which results from the buildup of fluid pressure within feeder conduit 28 . while in the stowed position of fig1 , nozzle body 236 is retained within feeder conduit 28 by frangible sealing disc 252 , which functions as a stowage seal by sealing against annular surface 258 formed in the end of feeder conduit 28 . frangible sealing disc 252 is maintained in contact with annular surface 258 by means of external seal retainer 260 , which is attached to the outer end of feeder conduit 28 . frangible sealing disc 252 serves not only to prevent the ingress of contamination into feeder conduit 28 when nozzle body 236 is in its stowed position , but also prevents the escape of fire suppression agent from the closed , or bulkhead end , 244 of nozzle body 236 . this feature may be used to tune or adjust the distribution of fire suppression agent from nozzle 232 . when nozzle body 236 is projecting telescopically from feeder conduit 28 , integral stop abutment and fluid seal 248 cooperates with internal stop abutment 256 formed at the end of conduit 28 to both seal the joint between nozzle body 236 and feeder conduit 28 , and to prevent nozzle body 236 from separating from feeder conduit 28 in response to the fluid pressure of the flowing fire suppressant agent . fig1 , 13 , and 14 illustrate another aspect of the present invention . a quick connect coupler attaches the fire suppressant feeder conduit to the suppressant reservoir . this facilitates assembly of the present fire suppression system in the underbody environment of a vehicle , thereby reducing assembly cost , while helping to assure integrity of the fire suppression system . reservoir 18 is equipped with a spud , 200 , having external threads , 204 . threads 204 are interrupted . the importance of this feature will be explained below . feeder conduit 28 has an annular retention flange , 208 , which abuts collar 216 when feeder conduit 28 is attached to reservoir 18 . a section of a fully assembled joint consisting of feeder conduit 28 , spud 200 , collar 216 , and o - ring seal 212 is shown fully assembled in fig1 . threads 220 , which are formed internally on collar 216 , cooperate with threads 204 formed on spud 200 to lock the various components together . o - ring seal is compressed between bore 202 of spud 200 and an outer surface of conduit 28 , so as to provide a leak - tight seal between spud 200 and conduit 28 . the joint of fig1 is made up by inserting conduit 28 into spud bore 202 until retention flange 208 abuts spud 200 . then , collar 216 is brought into contact with spud 200 and collar 216 is rotated to lock threads 204 and 220 . because each of threads 204 and 220 are interrupted — i . e ., they do not circumscribe the bases to which they are attached , collar 216 may be fully driven and seated upon spud 200 with less than one full revolution . this greatly facilitates assembly of the present system under a vehicle body . fig1 illustrates an anti - rotation feature provided by axially displaceable pints 224 . when collar 216 has been fully rotated upon spud 200 , pins 224 will be extended by compression springs ( one spring , 228 being shown ). once pins 224 have extended , rotation of collar 216 in a direction permitting detachment of collar 216 from spud 200 will be prevented because each of pins 224 will abut one of threads 204 formed on spud 200 . fig1 a and 15 b illustrate a fire suppressant reservoir , 264 , formed as a composite characterized by a pressure vessel having an outer wall , 268 , combined with a sealing liner , 272 . outer wall 268 may be formed from metal or fiber reinforced resin , or other metallic or nonmetallic materials or composites known to those skilled in the art and suggested by this disclosure . liner 272 is said to be a dynamic reservoir seal because liner 272 is sufficiently extrudable in response to fluid pressure produced by the propellant device that liner 272 will extrude or squeeze directly into discontinuities caused by the high operating pressure of the present fire suppression system . this extrusion will seal outer wall 268 , preventing an excessive loss of the fire suppressant agent . in fig1 b , portion 280 of liner 272 is shown as having extruded through discontinuity 276 . as shown in fig1 b , portion 280 is in sealing engagement with outer wall 268 . sealing liner 272 may be formed from plastics or metals , elastomers , composites , or yet other materials known to those skilled in the art and suggested by this disclosure . in any event liner 272 is selected to provide the pressure - driven extrusion characteristic needed to seal outer wall 268 if a high pressure leak develops in reservoir 18 . fig1 shows a second type of propellant useful for practicing the present invention . compressed gas cylinder 284 is pre - charged with a high pressure gas , such as nitrogen . valve 288 , which is operatively connected with controller 66 , is opened when needed to permit gas to flow from cylinder 284 and through high pressure conduit 292 , thereby initiating discharge of the fire suppressant agent from reservoir 18 . as but one alternative to the arrangement shown in fig1 , gas cylinder 284 could be located within reservoir 18 in the manner shown in fig1 a and 15 b , albeit at the expense of volume for the fire suppressant agent . the present compressed gas propellant provides a supply - chain advantage , inasmuch as non - pyrotechnic propellants are subject to less stringent shipping restrictions than are pyrotechnic devices . fig1 illustrates a system for connecting high pressure conduit 292 with reservoir 18 . a dome , 298 is provided in an upper surface of reservoir 18 . dome 298 has a port , 296 , through which conduit 292 extends into the interior of reservoir 18 . as conduit 292 is inserted , it displaces valve disc 308 and spring 312 . conduit 292 is retained within port 296 by means of retainer 300 , which passes through holes ( not shown ) formed dome 298 . once conduit 292 has been installed , high pressure gas may flow into reservoir 18 through a series of exit orifices 304 formed in conduit 292 . according to another aspect of the present invention , a fire suppressant agent used with this system may be either a single component , generally an aqueous - based preparation , or a binary system in which a primary component is carried within a first , or primary , reservoir , and a secondary component , such as potassium carbonate , is carried within a secondary reservoir accessible to the fire suppression system &# 39 ; s feeder conduits . passage of the primary component through a feeder conduit will cause the secondary component to be released such that the primary component and the secondary component will be combined before being discharged from the distribution nozzles . in essence , the purpose of the secondary component delivery system is to place the secondary component into a stream of primary component flowing within the present distribution system . if the secondary delivery system is housed within feeder conduit 28 , the need for an additional discrete reservoir for the secondary component may be avoided . fig1 a - 18 d illustrate several embodiments of secondary reservoirs . fig1 a shows a secondary reservoir defined by venturi tube 316 , which establishes an annular - shaped storage chamber , 320 within feeder conduit 28 . a number orifices , 324 are formed at the throat , 322 , of venturi tube 316 , such that primary component flowing through venturi tube 316 will cause secondary component 318 to be drawn through orifices 324 and aspirated into the flowing primary component stream . in the embodiment of fig1 a , secondary component 318 could be in either a liquid or a powder state . fig1 b illustrates a secondary reservoir having a generally cylindrical housing , 328 , which is filled with secondary component 318 in either a powder or gelatinous state . as with the embodiment of fig1 a , housing 328 is located within feeder conduit 28 . pressure - responsive piston 332 is displaced by the pressure of the flowing primary component , and , as piston 332 moves down the bore of cylindrical housing 328 , secondary component 318 will be expelled through discharge orifices 336 . fig1 c illustrates a secondary reservoir having a generally cylindrical housing , 340 , enclosing a quantity of secondary component 318 , preferably in either a gelatinous or powdered state . when the primary component is flowing through feeder conduit 28 , turbine 346 , as well as shaft 352 and shredder blade 356 , will rotate in the manner of a windmill . as a result , shredder blade 356 will cooperate with shredder plate 360 to pulverize secondary component 318 , which is forced through shredder plate 360 by piston 344 and compression spring 348 . fig1 d illustrates a sacrificial secondary reservoir having a hollow cylindrical plug or lining , 364 made from solid secondary component , such as potassium carbonate . lining 364 has a number of integral internal splines , 368 . lining 364 is formulated and processed so that flowing primary component will cause lining 364 to be eroded and entrained in the flowing primary component . with a composite fire suppressant reservoir , it is generally not possible to weld the initiator conductor conduit extending from an upper portion of the reservoir to a lower portion of the reservoir , to the reservoir itself . however , with the axially compliant conduit illustrated in fig1 , this problem is avoided , while permitting the initiator conductor to be protected against damage . conduit 384 is inserted into reservoir 18 after the pressure vessel shell , in this case , the outer wall of reservoir 18 , has been fabricated . this process begins with insertion of conduit 384 into the interior of reservoir 18 through assembly port 378 . installation of conduit 384 continues with placement of the conduit &# 39 ; s upper end , 384 a , into an upper conduit port formed in wall 18 a . then , axial compliance section 388 is compressed sufficiently to allow lower end 384 b of conduit 384 to be inserted to a lower conduit port located in lower wall 18 b . conduit 384 is then permitted to expand axially . then , an initiator conductor or wire , 380 may be inserted into conduit 384 . finally , propellant device 372 , which is attached to base 382 , may be mounted within port 378 . conduit 384 has an upset section , 396 , adjacent to each of its upper and lower ends , 384 a and 384 b , and these upset sections 396 lock into bonding flanges 392 , which are adhesively sealed to reservoir walls 18 a and 18 b . fig2 a - 20 c illustrate a method for assembling a composite fire suppression agent reservoir having a closure plug either made from a different material than the outer wall of the reservoir , or from a material which is not thermally weldable to the outer wall . fig2 a shows a preform having outer wall 400 , and inner reinforcement 404 . closure plug 406 has a circumferential groove , 406 a , which allows tension band 410 purchase to bind outer wall 400 and inner reinforcement 404 to closure plug 406 . plug 406 may be solvent welded , or bonded with various adhesives known to those skilled in the art , to outer wall 400 and inner reinforcement 404 . the embodiment of fig2 a - 20 c is especially useful for practicing a variant of the present invention in which an external propellant is employed . on the other hand , the embodiment of fig2 shows a combined structure in which closure plug 412 is also employed as a base for internally located propellant 372 . as before , plug 412 may be attached to the composite wall of reservoir 18 both mechanically by means of tension band 410 and / or by chemical bonding or friction welding . fig2 - 25 b show a reservoir construction based upon a composite wall , 424 , which may be formed from fiber or metal reinforced resin , or other composites known to those skilled in the art and suggested by this disclosure . the reservoir shown in fig2 , which is ideally constructed of composite material 424 , employs at least one double concave section to promote the adaptability of the reservoir for installation into spaces having irregular geometry . accordingly , reservoir 416 is shown with double concave section 420 , which is generally bowl - shaped . fig2 shows a first concavity , following the curve of arrow “ a ,” and fig2 a shows a second concavity following the curve of arrow “ b .” of course , both concavities originate at the outside of reservoir 416 . section 420 is reinforced by metallic doubler 428 , which may be insert molded to the interior surface of double concave section 420 . fig2 a illustrates an embodiment in which mold 426 has a groove , 427 , which forms an integral rib , 432 , on an outer portion of double concave section 420 during the process of molding reservoir 416 . fig2 b illustrates a similar embodiment in which rib 432 is formed on an inner surface of section 420 . in the interest of clarity , mold 426 is not shown in fig2 b , or fig2 a and 25 b . in the embodiments of fig2 a and 25 b , preformed ribs are insert molded to double concave section 420 . more specifically , in fig2 a , rib 436 is shown as having been insert molded to an outer portion of section 420 , and in fig2 b , rib 436 is shown as having been molded or bonded to an inner surface of section 420 . those skilled in the art will appreciate in view of this disclosure that insert molding may be accomplished by fabricating a preform , in this case ribs 436 , which are placed into the mold 426 prior to injecting and curing the resin . ribs 436 may be fabricated from either fiber - reinforced resin , or other metallic or non - metallic materials or composites known to those skilled in the art and suggested by this disclosure . 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 .
an onboard fire suppression system for a vehicle has at least one composite reservoir containing a fire suppressant agent . the reservoir includes a pressure vessel formed from fiber - composite material and having at least one double concave section . at least one reinforcement is applied to the pressure vessel in the location of the double concave section . this construction permits the pressure vessel to have a shape conforming with the irregular spaces commonly found in the underbody areas of vehicles .