Apparatus for preventing and extinguishing automotive vehicle fires
United States Patent Poitras 1 Apr. 8, 1975 1 APPARATUS FOR PREVENTING AND 3.515.218 6/1970 Gardner Ct a1 169/62 x EXTINGUISHING AUTOMOTIVE VEHICLE 3.568.774 3/1971 Meoule 169/62 X FIRES 3.602.312 8/1971 Ramaldl 169/47 3.630.288 12/1971 Tiberti et al. 169/62 X Edward J. Poitras, Holliston, Mass.  
 Walter Kidde &amp; Company, Inc., Clifton, NJ.  
 Filed: Feb. 19, 1974 Appl. No.: 443,514  
 Inventor:  
 Assignee:  
 US. Cl. 169/57; 169/62; 169/26 Int. Cl. A620 35/12 Field of Search 169/62, 56, 57. 60, 61,  
 References Cited UNITED STATES PATENTS l2/l935 Bouillon 169/66 X 8/1951 Mathisen 169/62 X 9/1969 Levy et a1. 169/62 X Primary Examiner-M. Henson Wood, Jr. Assistant E.\&#39;(1minerMichael Mar Attorney, Agent. or Firm-.lohn E. Toupal 1 71 ABSTRACT,  
 The present invention provides a system in which a significant collision impact of a vehicle is sensed and used to trigger the release of a fire-inhibiting fluid medium. Pressure is provided to expel onto the underside of the vehicles fuel tank the fluid medium, which is a dense adherent liquid at room temperature and capable of extinguishing gasoline fires. The expelled liquid coats the surface of the fuel tank so as to become mixed with and thereby prevent ignition of fuel escaping from any rupture in the tank.  
 . 5 Claims, 4 Drawing Figures PATENIEUAFR 81975 sum 2 n5 3 FIG.Z  
 BACKGROUND OF THE INVENTION DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1 there is shown an automo- This invention relates generally to fire prevention 5 tive vehicle 11 conventionally divided into a passenger and extinguishment and, more particularly, to a system for preventing or extinguishing fires that occur&#39;in automotive vehicles.  
  The high incidence of both serious bodily injuries and fatalities that are caused by automotive vehicle accidents is well known. Less well known, however, is the high percentage of such injuries and fatalities that result directly from fires accompanying such accidents. Department of Transportation statistics indicate that traffic accident related fires account for an estimated 2,000 to 3,500 deaths annually. Life-claiming automotive fires are most commonly initiated by rear-end collisions that cause fuel tanks to rupture after which leaking gasoline is ignited to produce a fiery disaster. The problem is often accentuated by door jams that prevent passengers that survive the initial crash impact from escaping the flames that are ignited and spread shortly thereafter.  
  The object of this invention, therefore, is to provide a fire protection system that will either prevent or quickly extinguish fires fueled by gasoline escaping from tanks ruptured as a result of collision impacts.  
 SUMMARY OF THE INVENTION The present invention provides a system in which a significant collision impact of a vehicle is sensed and used to trigger the release of a fire-inhibiting fluid medium. Pressure is provided to expel onto the underside of the vehicles fuel tank the fluid medium, which is a dense, adherent liquid at room temperature and capable of extinguishing gasoline fires. The expelled liquid coats the surface of the fuel tank so as to become mixed with and thereby prevent ignition of fuel escaping from determines the discharge path of the released extinguishing fluid.  
 DESCRIPTION OF THE DRAWINGS These and other objects and features of the present invention will become more apparent upon a perusal of the following description taken in conjunction with the accompanying drawings therein:  
 FIG. 1 is a schematic representation of a fire protection system installed on an automotive-vehicle;  
  FIG. 2 is a schematic, elevational view illustrating in greater detail several of the individual system components shown in FIG. 1;  
  FIG. 3 is a cross sectional plan view illustrating the selector valve shown in FIGS. 1 and 2; and  
  FIG. 4 is a side view of the selector valve shown in FIG. 3.  
 compartment 12, an engine compartment 13 and a cargo compartment 14. Mounted on the vehicle 11 is a fire protection system 15 having component parts positioned in both the engine compartment 13 and the cargo compartment 14. Located in the engine compartment 13 is a supply vessel 16 containing a dense, adherent fire extinguishing agent which is a liquid at room temperature. A highly preferred extinguishing medium is a dibromotetrafluoroethene having the following structure:  
 A source of pressure is provided by a pressurized container 17 coupled to the vessel 16 by a tube 18. Preferably the container 17 is filled with a vapor phase fluid such as bromotrifluoromethene, CBrF;,. As described in greater detail below, the container 17 includes a pilot volume operated differential pressure valve responsive to a detection system 21 comprising an hermetically sealed tubulation 22 including temperature detector appendages 23 and a collision impact detector appendage 24. A selector valve 25, also described in greater detail below, is connected for fluid communication with the outlet of the vessel 16 by a supply tube 26. Extending out of the selector valve 25 is an engine distribution tube 27 that terminates with a spray nozzle 28 disposed to discharge extinguishing fluid throughout the engine compartment 13. Also communicating with the selection valve 25 is a tank distribution tube 31 that extends through the passenger compartment 12 into an area below the cargo compartment 14. Terminating the tank tube 31 is a bifurcated pipe nozzle 32 mounted directly beneath the fuel tank 33 that supplies operating fuel for the vehicle 11. The nozzle pipe 32 has a plurality of fluid discharge openings that direct fluid passing through the tank tube 31 against the underside of the fuel tank 33.  
  Referring now to FIG. 2 there is shown in greater detail the pressure vessel 17. An open end 32 of the detector tube 22 communicates with the container 17 formed by a cap member 34 and a piston valve member 35. The container17 serves as a reservoir for a pressurized vapor phase fluid 37. The container 17 provides a pilot volume 38 for the valve 35 which is controlled by the difference between the pressure in the pilot volume 38 and that within the vessel 17. A neck portion 41 on the vessel 17 has external threads that receive the cap 34. Extending to near the bottom of the vessel 17 is an open end 42 of a dip tube 43 that is accommodated by the inner surface 44 of the neck portion 41.  
 The outer surface of the piston member 35 possesses an annular groove that receives an O-ring gasket 45 that provides a seal with the interior surface of the cylindrical cap 34. Fixed to the bottom of the piston 35 is a circular gasket 46 that seals against the top edges of the neck portion 41 and the dip tube 43. A recessed portion 47 in the neck 41 forms with the cap 34 an annular space 48 that is in fluid communication with a &#39;primary discharge tube 49 that is accommodated by an opening in the cap 34. Extending through both the piston member 35 and the gasket 46 is an orifice 49 that provides a leak path between the pilot volume 38 and the interior of the vessel 17. The top surface of the piston member 35 possesses an annular groove that retains a spring member 50. Prior to actuation of the detectors 23 or 24 leakage through the orifice 49 establishes within the tubing 22 and the pilot volume 38 a pressure substantially equal to that within the vessel 17. Consequently, the differential areas and pressures on opposite sides of the piston 35 in addition to the force. provided by the spring member 50 causes the piston to remain in the position shown in FIG. 2. An extremely tight seal between the gasket 46 and the vessel 17 is insured by the larger surface area that is exposed to fluid pressure on the top of the piston 35 as compared to the seal area at the surface of tube 43.  
  In response to a predetermined ambient temperature in the engine compartment 13 produced, for example, by a fire, the appendages 23 which are hermetically sealed with fusible metal plugs 30 will be vented in response to melting of those plugs. This will result in an immediate reduction of pressure within the pilot volume 38 in that the fluid conductance to atmosphere provided by the opened tubing 22 is substantially greater than that provided to the pressurized vessel 17 by the orifice 49. Accordingly, the piston 35 is forced upward to open the vessel 17 and allow pressurized discharge of the suppressant 37 through the supply tube 26. Thus, venting of the pilot volume 38 to atmosphere by fusing of the temperature detectors 23 or by opening of the collision detector appendage 24 in a manner described more fully below, opens the valve 35 allowing discharge of the pressurized fluid 37 out of the supply tube 18 into the source vessel 16. The resultant pressure created in the upper portion of the vessel 16 forces the extinguishing fluid 51 up through the discharge tube 26 into the selector valve 25 which distributes the discharged liquid to either of the nozzles 28 or 32 as described below.  
  Referring now to FIGS. 3 and 4 the selector valve assembly 25 includes a cylindrical valve drum 51 mounted for rotation within a cylindrical housing 52 and retained therein by a shoulder portion 53. A pas-- sage 54 through the valve drum 51 extends between&#39;a passage 55 in the housing 52 that communicates with the supply tube 26 and a passage 56 that communicates with the engine distribution tube 27. A shaft 57 extends from the valve drum 51 out of the housing 52 and is keyed for rotation to a collar 58. Extending in opposite directions from the collar 58 are an actuator arm 61 that terminates with a weight 62 and a calibration arm 63. A hollow outer portion of the calibration arm 63 retains a pin 64 that is biased outwardly by spring 65. The end of the pin 64-is normally retained by a detent 66 in a circular abutment surface 67 having a notched portion 68 displaced approximately 45from the detent 66.  
  The operation of the fire protection system will now be described. The elevated ambient temperatures accompanying the occurrence of a fire in the engine compartment 16 will cause fusing of one or both of the temperature detectors 23 and resultant discharge of pressurized fluid from the pressure container 17 into the vessel 16 through the tubulation 18 as described above. Extinguishing liquid forced out of the supply tube 26 by the resulting pressure in the vessel 16 passes through the housing openings and 56 and the valve passage 54 into the engine distribution tube 27. The pressurized fluid ruptures a diaphragm 70 and is discharged by the nozzle 28 into the engine compartment 13 thereby extinguishing fires present therein.  
  Conversely, the occurrence of a high force, impact collision by the vehicle 11 produces the following results. The acceleration forces accompanying the collision exert a force on the weight 62 (FIG. 4) that causes counter-clockwise rotation of the arms 61 and 63 assuming that the force is sufficient to force the pin 64 out of the detent 66. Obviously, the various parameters such as the weight 62, the spring force generated by the spring 65, the size of the detent 66 and the lengths of the arms 61 and 63 are selected so as to establish release of the pin 64 only in response to the forces generated by an impact of sufficient magnitude to produce substantial damage to the vehicle 11, i.e., damage sufficient to cause damage to fuel tank and fuel spillage. After movement of the arm 61 through approximately 45, the weight 62 strikes a terminal portion 71 of the hollow collision detector appendage 24. The terminal portion 71 is made of a suitably brittle material such as hardened metal or glass and is further weakened by an annular recess 72 extending around the appendage 24.  
 Impact by the weight 62 severs the terminal portion 71&#39; from the appendage 24 and thereby vents the pilot volume 38 in the container 17 to atmospheric pressure and induces release of the pressurized fluid 37 in the manner described above.  
  This movement of the arm 61 is accompanied by equivalent movement ofthe pin 64 along the surface 67 until the pin 64 reaches and is forced into the recess 68 by the spring to thereby retain the arms 61 and 63 in that position. Accompanying this movement of the arms 61 and 63 is equivalent counter-clockwise rotation of the valve drum 51 which moves the valve passage 54 out of registration between the supply tube 26 and the engine distribution tube 27. The movement produces, however, registration between both one end of the valve passage 54 and an opening 74 in housing 52 that connects with the tank distribution tube 31 and between the supply tube 26 and an auxiliary valve passage 73 extending through the valve drum 51 and into the valve passage 54 and oriented at approximately 45 therewith. Thus, extinguishing liquid expelled from the vessel 16 now passes through the supply tube 26, the auxiliary valve passage 73 and one half of the valve passage 54 into the tank distribution tube 31. The liquid extinguishing medium is then discharged by the nozzle pipe 32 against the underside of the fuel tank 33 to which some adheres providing a fire inhibiting coating thereon while the remainder drops to the ground below. Consequently, any gasoline escaping from the tank 33 through ruptures created by the activating collision comes into contact with the extinguishant coating on the tank or the extinguishant on the ground below and is inhibited thereby to prevent ignition of the gasoline by any inadvertently generated ignition source such as frictional sparking, electrical arcing or hot components. It will be obvious that in the event that the collision causes roll over of the vehicle 11, the liquid medium expelled by the nozzle pipe 32 will flow over the surface of the tank 33 toward whatever tank surface is lowest after the vehicle comes to rest.  
  Obviously, many modifications and variations of the present invention are possible in light of the above 5. teachings. It is therefore, to be understood that within the scope of the appended claims the invention can be practised otherwise than as specifically described.  
  What is claimed is: 1. Apparatus for preventing or extinguishing fires in motor vehicles comprising:  
 a source of a fluid fire extinguishing medium; distribution means comprising engine distribution means for conveying extinguishing medium to the engine of said vehicle, and tank distribution means for conveying extinguishing medium to the fuel tank of said vehicle; release means for inducing release of extinguishing medium from said source into said distribution means; plurality of detector means for actuating said release means to induce release of extinguishing medium, said detector means comprising a temperature responsive detector means disposed to sense the ambient temperature in a regionadjacent said engine and a vehicle acceleration responsive detector means; andv selector valve means for connecting said source to said engine distribution means in response to detection of excessive temperature by said temperature responsive detector and connecting said source to said tank distribution means in response to detection of an excessive rate of vehicle acceleration by said acceleration responsive detector.  
  2. Apparatus according to claim 1 wherein said release means comprises pressure source means for inducing discharge of said extinguishing medium from said source.  
  3. Apparatus according to claim 2 including control means for actuating said pressure source means in response to either detection of excessive temperature by said temperature responsive means or detection of excessive vehicle acceleration by said acceleration responsive means.  
  4. Apparatus according to claim 3 wherein said tank distribution means comprises nozzle means disposed to discharge extinguishing medium over the underside of said fuel tank.  
  5. Apparatus according to claim 4 wherein said source comprises a source of dibromotetrafluoroethane having the following structure: