Abstract:
An automotive vehicle includes a vehicle body and at least 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 discharge port controlled by a piloted spool valve actuated by pressure generated by a propellant device.

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 for an automotive vehicle includes at least one reservoir containing a fire suppressant agent and a propellant which is operatively associated with the reservoir and which expels the fire suppressant agent from the reservoir, as directed by a system controller. A distribution system receives fire suppression agent expelled from the reservoir and distributes the depressant agent in at least one location external to a vehicle. A spool valve, located between the reservoir and the distribution system, controls a flow of suppressant agent from the reservoir to the distribution system. The spool valve is responsive to fluid pressure within the reservoir and prevents suppression agent from flowing into the distribution system unless the fluid pressure within the reservoir exceeds a predetermined threshold.  
         [0008]     In a preferred embodiment, a distribution system may include at least one feeder conduit attached to the reservoir and at least one suppressant nozzle attached to the feeder conduit.  
         [0009]     According to another aspect of the present invention, the present spool valve includes a valve body and a valve seat formed in the valve body. A control chamber is also formed in the valve body. A shuttle is positioned in the valve body for sliding movement, with the shuttle including a flow control pintle mounted upon the first end of a valve stem, with the flow control pintle cooperating with the valve seat to control flow through the spool valve. A control piston is mounted within a control chamber upon a second end of the valve stem. The control piston moves the flow control pintle to an open position when a pilot valve mounted within a control passage extending from the reservoir to the control chamber allows fluid to flow from the reservoir to the control chamber, so as to cause the control piston to slidably move the shuttle. Of course, because the flow control pintle is attached to the shuttle, movement of the control piston cause the flow control pintle to move to an open position. The spool valve is calibrated so that opening of the flow control pintle will occur only if the pressure within the reservoir exceeds a predetermined threshold pressure.  
         [0010]     According to another aspect of the present invention, the valve stem preferably comprises a generally cylindrical member, with a control passage comprising an axially cored passage having a valve seat upon which a pilot valve element is biased in a normally closed position. The pilot valve preferably comprises a spring-loaded poppet mounted within the control passage.  
         [0011]     It is an advantage of the present fire suppression system that a precise discharge pressure may be tuned through the use of appropriate resilient elements, such as springs, associated with a control piston and pilot valve mounted within the present discharge control valve.  
         [0012]     Other advantages, as well as features and objects of the present invention will become apparent to the reader of this specification. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a ghost perspective view of an automotive vehicle having a fire suppression system according to the present invention.  
         [0014]      FIG. 2  is an exploded perspective view of a portion of a fire suppression system according to the present invention.  
         [0015]      FIG. 3  is a perspective view of a control module used with a system according to the present invention.  
         [0016]      FIG. 4  is a perspective view of a manually activatable switch used with a fire suppression system according to the present invention.  
         [0017]      FIG. 5  illustrates a portion of a wiring harness used with the present system.  
         [0018]      FIG. 6  is a flowchart showing a portion of the logic used to control a system according to the present invention.  
         [0019]      FIG. 7  is a cutaway perspective view of a fire suppression agent reservoir according to one aspect of the present invention.  
         [0020]      FIG. 8  is a perspective view of a variable geometry fire suppression agent nozzle according to one aspect of the present invention.  
         [0021]      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.  
         [0022]      FIG. 10  is a perspective view of a vehicle having a fire suppression system with a reservoir having a piloted spool valve for controlling a discharge port according to one aspect of the present invention.  
         [0023]      FIG. 11  is a perspective view of a suppression agent reservoir according to one aspect of the present invention.  
         [0024]      FIG. 12  is a sectional view of a portion of the reservoir of  FIG. 11 , taken along the line  12 - 12  of  FIG. 11 .  FIG. 12  shows the inventive piloted spool valve in a closed position.  
         [0025]      FIG. 13  shows the piloted spool valve of  FIG. 12  in an open position. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0026]     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 .  
         [0027]      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.  
         [0028]     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.  
         [0029]     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. Such propellants may be mounted either within a reservoir with the fire suppressant agent, or externally thereto. 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.  
         [0030]      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 .  
         [0031]     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-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  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 .  
         [0032]     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 .  
         [0033]      FIG. 6  shows a sequence which is used according to one aspect of the present invention for activating a release of fire suppressant agent.  
         [0034]     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.  
         [0035]     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 .  
         [0036]     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 .  
         [0037]     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.  
         [0038]     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.  
         [0039]     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 .  
         [0040]      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.  
         [0041]     As shown in  FIG. 10 , vehicle  200  has a controller,  204 , for operating the present onboard fire suppression system. Upon the appropriate command, propellant  210  (shown in  FIG. 11 ) discharges suppressant agent from multiple reservoirs  208 . The suppressant distribution system  212  includes at least one feeder conduit  224 , and at least one nozzle  228 . Propellant  210  may be located either within reservoir  208 , or externally thereto.  
         [0042]     Spool valve  216  is mounted between distribution system  212  and reservoir  208 . The purpose of spool valve  216  is to control the flow of suppressant agent  214  from reservoir  208  to distribution system  212 .  
         [0043]     Operation of spool valve  216  is best understood with references to  FIGS. 12 and 13 .  FIG. 12  shows spool valve  216  in its closed position, with  FIG. 13  showing spool valve  216  in an open position which allows discharge of suppressant agent  214  through distribution system  212 .  
         [0044]     Spool valve  216  includes a valve body,  232 , having a discharge port  220 . Flow through discharge port  220  is controlled by flow control pintle  244 , which is mounted to a first end,  248   a , of valve spool stem  248 . A control piston,  252 , is mounted to a second end,  248   b , of valve spool stem  248 . Those skilled in the art will appreciate in view of this disclosure that flow control pintle  244 , valve spool stem  248 , and control piston  252  may either be unitary, or separate components combined in a single assembly.  
         [0045]     During standby operation of the present onboard fire suppression system, flow control pintle  244  is maintained in contact with valve seat  236  by means of compression spring  254 , which bears against control piston  252 . During standby operation, bleed orifice  256  assures that no pressure will build within a control chamber,  240 , which extends between valve body  232  and control piston  252 . If, however, propellant  210  is activated, pressure will build rapidly within reservoir  208 , and pilot poppet  264 , which is located within control passage  260 , will be forced off of seat  268  against the force of spring  270  when a predetermined threshold pressure has been reached, and this will allow gas from propellant  210  and/or depressant agent  214  to enter control chamber  240 . Although control passage  260  is shown as an axially cored passage within valve spool stem  248 , passage  260  may be constructed as a series of drillings or cast passages (not shown) within valve body  232 , with pilot poppet  264  being located within such alternative passage.  
         [0046]     Because the area of control piston  252  is much greater than the area of flow control pintle  244 , the pressure within control chamber  240  will cause control piston  252  to move flow control pintle  244  into the opening direction against the force of spring  254 , and, as shown in  FIG. 13 , agent  214  will be allowed to leave reservoir  208 . The operating characteristics of valve  216  may be tuned readily by changing springs  254  and  270 .  
         [0047]     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.