Patent Publication Number: US-4256181-A

Title: Automatic stove top fire extinguisher

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is related to fire extinguishing apparatus, and in particular, to automatically actuated stove top fire extinguishing systems. 
     2. Description of the Prior Art 
     Numerous different types of systems have been developed to automatically extinguish grease and other types of fires originating on the top of stove type cooking appliances. U.S. Pat. No. 3,448,808 (Scofield) discloses an automatically actuated fire extinguishing system having a remotely located pressurized cylinder of fire extinguishing material, a plurality of nozzles for discharging fire extinguishing material onto the top of the stove, and a cord including a plurality of fusible links extending throughout the vent hood above the stove. The valve of the fire extinguisher is maintained in the closed position by the tension exerted thereon by the cord. When any one of the fusible links positioned throughout the system is severed by a fire, the tension force from the cord is released which permits the valve of the fire extinguisher to be opened and its contents to be discharged. U.S. Pat. No. 3,772,499 (Fritzche) discloses a fire extinguishing system which not only discharges fire extinguishing material onto a fire, but which also de-energizes the cooking device causing the fire to prevent reoccurence of the fire. This system utilizes fusible links positioned directly adjacent to potential fire areas. The fusible link is severed by the flames from the fire causing the fire to be extinguished and the cooking apparatus to be de-energized. U.S. Pat. No. 3,283,827 (Diehl) discloses a manually controlled carbon dioxide fire extinguisher system including a fan for drawing the carbon dioxide up the ventilator duct of the vent hood. This system must be manually actuated after a fire has been observed. 
     U.S. Pat. No. 3,653,433 (Doskery) discloses an electrically actuated fire extinguishing system including a solenoid and a thermostat for extinguishing stove top fires. U.S. Pat. No. 3,584,688 (Doncan) discloses an automatically actuated fire extinguishing system positioned above a deep fat fryer. This system is actuated when flames severe a fusible link releasing the pressure on a normally opened valve in a fire extinguisher causing it to discharge its contents. This system includes apparatus for automatically reducing the flow rate of fire extinguishing material and for causing a flow of fire extinguishing material for a predetermined time in order to prevent reoccurrence of a fire immediately after the fire has been extinguished. 
     U.S. Pat. No. 3,773,111 (Dunn) discloses an automatic stove top fire extinguishing system having a cylindrical container filled with a fire extinguishing powder. A pyrotechnic fuse is positioned in the lower portion of the vent hood above the cooking surface of the stove. When the fuse is ignited it discharges a pressurized aerosal container causing a piston to be displaced within the cylinder of the fire extinguisher. The increased pressure on the fire extinguishing powder opens a plurality of holes in a sealed nozzle causing the fire extinguishing powder to be discharged onto the fire. 
     U.S. Pat. Nos. 3,884,307 and 3,884,306 (Williams) disclose fuse actuated fire extinguishers which when activated by fire release the powdered fire extinguishing material from the unit and permit it to fall by gravity onto the fire. 
     U.S. Pat. No. 3,463,233 (Haessler) discloses a method of producing a soap foam for extinguishing fires in deep fat fires. Another type of foam generating fire extinguisher is disclosed in U.S. Pat. No. 3,356,148 to Jamison. 
     SUMMARY OF THE INVENTION 
     The present invention contemplates pyrotechnic sensor means remotely positioned from a fire extinguisher having a normally closed valve which is biased to the open position but maintained in the open position by a fusible link. When the pyrotechnic sensor means is ignited by the flames emanating from a fire, it controllably transfers the fire to the fusible link. When the fusible link is severed the valve on the fire extinguisher is biased to the open position. The fire extinguishing material is discharged through a manifold into the remotely located area in which the pyrotechnic sensor means is positioned. 
     Am important aspect of the present invention is that a conventional reusable fire extinguisher can readily be modified to be automatically actuated when a fire is detected. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The invention is pointed out with particularity in the appended claims. However, other objects and advantages together with the operation of the invention, may be better understood by reference to the following detailed description taken in connection with the following illustrations wherein: 
     FIG. 1 is a partially cut away perspective view of a fire extinguishing system of the present invention positioned above a stove having a vent hood. 
     FIG. 2 is an enlarged view, partially cut away, of the system illustrated in FIG. 1. 
     FIG. 3 is a schematic representation of the components of the present invention. 
     FIG. 4 is a schematic representation of a system of the present invention incorporating two separate fire extinguishers. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In order to better illustrate the advantages of the invention and its contribution to the art, a preferred hardware embodiment of the invention will now be described in some detail. Referring now to FIGS. 1 and 3, the automatic stove top fire extinguisher includes a pressurized container 10 of fire extinguishing material. A fire extinguisher having a 5BC rating is utilized in the preferred embodiment. Fire extinguisher 10 includes a lever actuated valve 12 having a normally closed position and an open position. The valve is spring biased to the closed position by springs 26 which are secured to the lever arms 28 of valve 12. 
     The body of fire extinguisher 10 is coupled by a mounting strap to the interior wall 14 of the cabinet section to which the vent hood 16 is secured. Vent hood 16 is typically positioned directly above the upper surface of a gas fired or electrically heated stove 20. 
     A multi-element discharge manifold 18 is coupled to valve 12 and includes a plurality of nozzles 22 which are positioned within vent hood 16. 
     One end of a fusible link 24 such as a nylon cord is coupled to clip 23 which is secured to valve 12 while its other end is coupled to toggle bolt 27. Toggle bolt 27 is maintained in position by link 24 and serves to maintain valve 12 in the closed position to oppose the forces exerted on valve 12 by biasing means on spring 26. 
     Referring also now to FIG. 2, a plastic container 30 of flammable material surrounds fusible link 24. Typically a flammable material such as gun powder is positioned within the interior of container 30. A flexible conduit 32 extends from container 30 to an area within vent hood 16. A powder loaded fuse 34 penetrates into the interior of container 30 and extends through conduit 32 into an area within vent hood 16. An end of fuse 34 extends beyond conduit 32 into the area below vent hood 16. 
     FIG. 4 illustrates an additional embodiment of the present invention which includes two fire extinguishers 10 and either one or two conduits 32 each of which includes a section of fuse 34. Ignition of the fuse within either of these conduits will cause the system to be actuated and both of the fire extinguishers to be discharged. 
     When the flames from a fire on the surface of stove 20 reach the tip 35 of fuse 34 or are drawn to the tip of the fuse by the circulation caused by a vent fan, the fuse will be ignited and will controllably transfer fire from the top of stove 20 to the interior of container 30. The container 30 and the gun powder serve as a releasing means. When the powder within container 30 is ignited by fuse 34, fusible link 24 is severed releasing toggle bolt 27 from valve 12. Lever 28 and valve 12 are displaced by spring 26 into the open position causing the contents of fire extinguisher 10 to be discharged. The contents of fire extinguisher 10 are discharged through manifold 18 and nozzles 22 over the upper surface of stove 20. Stove top fires are thus readily detected by the pyrotechnic sensor means which includes container 30, the powder therein, housing 32 and fuse 34. 
     It will be apparent to those skilled in the art that the disclosed automatic stove top fire extinguisher may be modified in numerous ways and may assume many embodiments other than the preferred forms specifically set out and described above. For example, many materials other than nylon cord my be used in place of fusible link 24. Accordingly, it is intended by the appended claims to cover all such modifications of the invention which fall within the true spirit and scope of the invention.