Abstract:
An improved fire protection system that is of fail safe design for kitchen stoves and other applications utilizing gas for generating heat and in which a fire condition such as a skillet of grease becomes ignited. Said system is activated thermally to release a quantity of fire suppressant material onto the top of the stove quenching the fire while simultaneously cutting off the cooking gas. The system utilizes a reservoir containing the fire suppressant under pressure with a hose or pipe connected to one or more thermally activated spray heads. A second hose or pipe is connected to a pneumatically operated gas cut off valve. The activation of the thermally activated spray head or heads exhausts the pneumatic pressure of the reservoir thereby causing the gas cut off valve to close against the cooking gas.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a division of application Ser. No: 11,647,055 Filing Date: Dec. 27, 2006 Art Unit 3752 
     
    
     FEDERALLY SPONSORED RESEARCH 
       [0002]    Not Applicable 
       SEQUENCE LISTING OR PROGRAMS 
       [0003]    Not Applicable 
       BACKGROUND OF THE INVENTION 
       [0004]    1. Field of Invention 
         [0005]    This invention relates to an automatically actuated totally pressurized fire extinguishing system to fit all near wall kitchen stoves with or without a range hood. The invention includes a unique means of automatic shutoff of the heating gas to the stove. 
         [0006]    2. Prior Art 
         [0007]    The use of automatically activated fire extinguishing devices for cooking stoves is known. Such devices provide a source of fire extinguishing compound to be released on to a stove surface in the event of a fire which occurs during use of the appliance. Virtually all prior art devices are designed and made only for installation within a range hood though preference today often calls for a microwave oven mounted over the cooking stove or such device without a traditional range hood, thereby eliminating the mounting space for the prior art devices. 
         [0008]    Even the smallest prior art device installed in a range hood leaves much to be desired in appearance due to the wires, pipes extinguishing nozzles and tanks that can be easily seen by persons near the stove and over time collect unsightly grease and dirt and are difficult to clean. 
         [0009]    Prior art automatic fire extinguishing installations sometimes include and automatic shutoff arrangement for shutting off the heating gas to the stove upon detection of a fire. Known shutoff arrangements are generally complex, expensive, and present added components subject to faults and errors in installation and operation. Such devices quite often require professional services such as electricians for their installation, thus this also contributes to onsite installation time and expense. 
         [0010]    There is thus a need in the art for a fire extinguishing device which is unobtrusive in appearance, is fail safe, and lends itself to quick and easy installation without the need for professional services. 
         [0011]    The following discussed patents are a good representative sample of all prior art patents found. 
         [0012]    Prior inventors such as U.S. Pat. No. 4,313,501 to Eckert (1982) have relied on taught wires with fusible disks for their operation under a range hood while the fuel flow to the fire is shut off by a cable arrangement operating through a torturous path to a valve handle. Very little information is provided as to how this is to be done. 
         [0013]    Another invention, U.S. Pat. No. 4,979,572 to Mikulec, (1990) again requires a range hood for its operating space and electrical power to the stove is cut off by an arrangement to pull the electrical feed plug from the wall and is activated by a cable means similar to the previously mentioned patent by Eckert. This method was later seen as impractical and was later dropped in a succeeding patent, Mikulec U.S. Pat. No. 5,899,927 (1999), for a much more complicated interruption method. A gas valve for shutting off the gas supply to a gas operated stove is also operated by pulling a cable and releasing a spring powered valve. An alternate method of interrupting the gas supply is offered by Mikulec in U.S. Pat. No. 5,899,927 with an acoustically operated electronic system which introduces more complication and possibility of error unless the owner is well versed in testing and maintenance of the system. Both means of operation require considerable on site labor for both installation, adjustment, and some components could fail during an emergency. 
         [0014]    U.S. Pat. No. 5,297,636 by North (1994) Requires a range hood and utilizes a gas valve for gas shut-off that is spring powered and the release of the pressurized gas in the extinguishment tank when released by the activation of a fusible link and operation of a wire that opens a valve to the extinguishment tank provides a puff of pressurized gas from the extinguishment tank that thereby causes the cut-off of the gas valve. The Reynolds gas valve shuts off the gas supply when the pressure from the extinguishment tank is exhausted. 
         [0015]    U.S. Pat. No. 4,984,637 by Finnigan (1991) again requires a range hood to hide the mechanism and uses a thermocouple and accompanying electronics to give a temperature display and sound an alarm. A brief mention is made that relays and valves can be used to cut off the stove heating energy. The main emphasis of this patent is that the system will turn off water or other suppressants when the temperature drops. This does not really solve the problem of a grease fire for water is the wrong material to use in such an instance and further the system is intended for a large liquid reservoir system to utilize the cycling on and off. 
         [0016]    U.S. Pat. No. 5,127,479 by Sthling et al. (1992) is strictly a range hood system much like the previously mentioned patents by Mikulec which utilizes cables and chain with heat melting links. A 12 volt battery back up system is referred to for powering an undefined valve or relay to cut off gas or electricity to the stove. If the home owner does not check the battery system regularly the system could easily fail to shut off the stove energy source in a fire emergency. 
         [0017]    U.S. Pat. No. 5,207,276 by Scofield (1993) operates only with a range hood and utilizes a twisted pair of wires in which the insulation melts to allow the two wires to short. The operation of the system depends on a battery backed up system. Energy cut off to the stove, though critical, is not mentioned. 
         [0018]    U.S. Pat. No. 5,868,205 by Cunningham et al. (1999) is designed to be used only with a range hood and has no means to cut off energy to the stove. 
         [0019]    U.S. Pat. No. 5,697,450 by Stehling, et al. (1999) is a fully electronic system for a range hood with acoustic triggered cut off of gas or electric energy to the stove. This system is totally dependent on electrical power and is subject to many faults and consequently is not fail safe. Blocking any of the acoustical properties by accumulation of dirt behind the stove by the system could prevent the shut off of energy to the stove. 
         [0020]    U.S. Pat. No. 6,044,913 by Stehling et al. (2000) is an electrical system for a range hood fully dependent on battery power and acoustically linked to the energy shut off. This system therefore has the same limitation as U.S. Pat. No. 5,697,450 by Stehling (1999) listed above. 
         [0021]    U.S. Pat. No. 6,276,461 by Stager (2001) is a mechanically operated system for a range hood and has no provision for disrupting energy to the stove which could make the system ineffective. 
         [0022]    U.S. Pat. No. 3,866,687 Banner 02-1975 Makes reference to operation with or without a range hood. the Banner system applied to a range hood utilizes a pressurized tank with piping to an electrically operated valve with nozzles within the range hood and beneath the burners. The pressurized tank is equipped with a pressure operated meter which is a requirement of approving authority when using unsealed pressurized fire extinguishing tanks. In applying the system to either a range hood or beneath the burner Banner uses electrically operated valves for discharge of the fire suppressant beneath the burners, which might prove less than effective. 
         [0023]    U.S. Pat. No. 4,356,870 Gaylord et al. Nov. 2, 1982 System is for range hoods only and utilizes an electrically operated solenoid valve for cut off of the gas and presumably uses an electrically energized relay to cut off the electrical power, which usually requires wiring and electricians. The system utilizes a spray nozzle which is connected to the building water supply and is usually considered to be the wrong material to fight a grease fire. 
         [0024]    U.S. Pat. No. 4,830,116 Walden et al. May 16, 1989 System is for range hoods and utilizes electrical equipment to disconnect the power source. 
         [0025]    U.S. Pat. No. 5,351,760 Tabor Jr. Oct. 4, 1994 System is for range hoods. Tabor claims the system is pressurized but it is actually pressurized only to an electrically operated release valve adjoining the retardant tank. The spray nozzle of this system is a passive device and is not thermally actuated. Further the spray nozzle has to spray material of a viscosity of one, which is probably water and the nozzle is a cooling spray nozzle of limited capacity usually associated with cooling back porches. 
         [0026]    These prior art devices have the disadvantage of being designed only for under or within a range hood even though today thousands of kitchens are designed with a microwave oven with exhaust in place of the range hood. Some require taught wires that require some experience to install and are in a position under a range hood to collect grease and dirt and with such pipes, wires, and other paraphernalia will be difficult to clean. Others rely on electronics for acoustically operating the disruption in electricity or gas and are inherently less reliable than a fail safe system. It must be kept in mind that the average home owner will seldom think of maintenance for such a system and therefore systems of such design can fail long before they are needed in an emergency. 
       OBJECTS AND ADVANTAGES 
       [0027]    There is a need in the art for a fire extinguishing system which will satisfy the needs of those kitchen type stoves that do not have range hoods and to provide a system that will be of low cost to install, have high reliability, and not require professional services in its installation. Accordingly, several objects and advantages of the present invention are: 
         [0028]    (a) to provide a fire extinguishing system for a cooking type stove that is fail safe; 
         [0029]    (b) to provide a fire extinguishing system that can be installed without the need for professional services; 
         [0030]    (c) to provide a fire extinguishing system that will be versatile and allow installation of components in other than a single type of application; 
         [0031]    (d) to provide a fire extinguishing system that can interface with a number of different extinguisher nozzles to meet differing requirements; 
         [0032]    (e) to provide a fire extinguishing system in which its cooking gas connection to a stove is a simple screw in pipe connection. 
         [0033]    Still further objects and advantages will become apparent from a consideration of the ensuing description and drawings. 
       SUMMARY 
       [0034]    In accordance with the present invention a fire extinguishing system of fail safe design for kitchen type stoves that not only provides fire sensing and extinguishing but also provides effective disconnection of the energy source for heating and does not require professional services in its installation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0035]    For a full understanding of the invention the following detailed description should be read in conjunction with the drawings, wherein: 
           [0036]      FIG. 1  is a perspective view of the fire extinguishing apparatus of the present invention applied in this instance to a gas stove without a range hood. 
           [0037]      FIG. 2  is a perspective view of the control unit showing its associated parts. 
           [0038]      FIG. 3  is a perspective view of the control unit mounted typically in a cabinet. 
           [0039]      FIG. 4A  is a side view of the pressure operated gas valve. 
           [0040]      FIG. 4B  is a cross sectional view of the pressure operated gas valve. 
           [0041]      FIG. 4C  is an exploded view of the pressure operated gas valve. 
           [0042]      FIG. 4D  is an exposed perspective view of the pressure operated gas valve when sufficient pressure is applied to the piston and the operator is cocked holding the gas valve open to flowing gas. 
           [0043]      FIG. 4E  is an exposed perspective view of the pressure operated gas valve when pressure on the piston is exhausted and the operator is released causing the closing of the gas valve. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0044]    The preferred exemplary embodiments of the invention are illustrated in  FIG. 1  through  FIG. 4E  wherein like numerals represent like parts. In the drawings, closely related figures have the same number but different alphabetic suffixes. Each segment of the system is discussed in detail individually. 
         [0045]    A preferred embodiment of the complete system in  FIG. 1  for application to a gas stove  40  without a range hood but with a microwave oven  54  is illustrated with the control unit  100  located in a cabinet  24  and connected by high pressure hose or pipe  34  to a pressure operated gas cut off valve  200  which receives the flammable gas by means of a supply line  18  and passes the gas through to the stove burners  50  by means of a supply line  22 . 
         [0046]    Fire suppressant under pressure is incorporated in the said control unit that supplies pressurized gas and extinguishment to a thermally actuated spray head  500 . The said control unit may be mounted in a cabinet over the said stove  24   FIG. 1  or any near by space within an engineer approved distance. Said hoses or piping would be generally installed inside the wall space on both existing and new construction. 
         [0047]    In the event of a skillet or other container  56  being left on the said stove and becoming overheated a fire  52  will soon result activating the said spray head thereby releasing the pressurized extinguishing agent  32  in the hoses or piping and originating in the said control unit spraying the top  46  of said stove, thereby extinguishing said fire. The resulting loss of pressure within the system releases a latching device in said gas valve cutting off the flow of cooking gas to the said stove thereby removing the source of the heat to the skillet. The loss of pressure also causes an alarm pressure operated switch  400  to activate switches to transmit an alarm to a local panel or remote monitoring station. 
         [0048]      FIG. 2  illustrates a control unit  100  while  FIG. 3  illustrates a control unit as it would normally be housed in a cabinet  122 . The said control unit includes a vessel  112  under pressure and containing fire suppressant. 
         [0049]    The said vessel  112  is initially installed with full design pressure as indicated with pressure gauge  102 . When placing the system in operation after installation and verifying its integrity, the fire suppressant release lever  104 A is depressed against the fixed device  104  and permanently locking an internal valve in an open condition by applying a locking device  106  which will sufficiently hold the internal valve of the vessel  104 B in a potentially dischargeable condition. 
         [0050]    The said vessel is in communication with the said suppressant system by hose or pipe  108  through a connector  110  to piping connecting to a connection device for hose or piping  114  allowing passage of gas propellant from said vessel to the said thermally actuated spray head  500  through said hose or piping  FIG. 1  and  FIG. 2 . 
         [0051]    Pressure within the said vessel also feeds through connecting piping  140  through a conventional in line filter  116  to a hose barb or connector  120  to apply pressure to gas valve  200   FIG. 1 . Said pressure also is applied through said connecting piping to the pressure operated alarm monitoring switch  400  and to a pressure gauge  124  whose purpose is for initial leak detection and setup operation with the initial gas for testing being induced through valve stem  118  prior to opening said valve  104 B. 
         [0052]    A cabinet  122   FIG. 3  constructed of material adequate for the purpose provides restraining strapping  128  for restricting movement of the said suppressant vessel. Additional restraining devices  126  hold the companion piping and devices in a restrained and vertical position to limit the effect of any powdery suppressant that may pass through the filter  116 . 
         [0053]    Said cabinet  122  shall include a cover with a means of holding the cover in a closed position with the aid of latching device  132  engaging another cabinet mounted device  134  to hold said cover in a closed position when not being serviced. A penetration  138  is provided within the said cabinet for connection of the fire suppressant discharge hose or piping  28   FIG. 1  and  FIG. 2  and another penetration is provided for the pressure line  34   FIG. 1 . An additional penetration  130   FIG. 3  is provided for installing an alarm monitoring cable for connection to the said alarm monitoring switch  400 . 
         [0054]    The said extinguishing unit can be placed in kitchen cabinets  24 , as shown in  FIG. 1  or can also be mounted in any other convenient space such as an adjoining room or even an attic space with reasonable access provided such location is within a predetermined maximum distance provided through engineering calculations that is adequate for transmission of the fire suppressant by means of the high pressure hose or piping  28   FIG. 1 . 
         [0055]    A pressure operated gas valve  200  as shown in  FIG. 1  is shown in detail in the following  FIG. 4A  through  FIG. 4E  and is designed to operate with in the totally pressurized system previously described and is designed to provide a convenient and easily installed device for interrupting gas flow to a cooking stove in the event of a fire and in which the extinguishing system is operated. Other methods of operating the said gas valve within a pressurized system are possible but the method portrayed here is what is presently preferred. 
         [0056]    The side view of the valve operator case  272  with cap  202  and gas valve  254   FIG. 4A  displays its outside appearance and includes a hose barb or connector  208  for receiving gas pressure from the control unit  100 . A cocking lever  228  is provided to initially cock the said gas valve in an open position to pass cooking gas energy to a gas stove  40   FIG. 1 . Gas pressure from the said control unit  100   FIG. 2  is induced into the said hose barb or connector and the said valve can then be locked in the open position. When the gas pressure from the said control unit is sufficiently reduced, the mechanism of the said pressure operated gas valve will operate to close the valve and the said cocking lever  228  will rapidly swing in a position as to close the said valve  254 . 
         [0057]    A cross sectional view is shown in  FIG. 4B . The case  272  provides support for components; valve adaptor ring  266  and spring base disk  262 , while providing guidance for the piston operating disk  248 . In viewing  FIG. 4B  cross sectional drawing and  FIG. 4C  exploded view it can be seen that a valve extension shaft  242  with a female slot  250  fits snugly around the valve stem  256 . Said valve is fitted with an adaptor ring  266  which is locked in place around the top of said valve with two locking set screws  240  set in threaded holes and engaging two unthreaded holes  252  in said gas valve. The said valve operator case then fits to the said adaptor ring and is secured by screws  244  into holes  244 B and to threaded holes  244 A in said adaptor ring thereby providing a ridged mount for other components. 
         [0058]    Said spring base disk  262  harbors a smooth round hole  238  which does not restrict the turning of said valve extension shaft. Said spring base disk is locked rigidly to the said valve operator case with screws  205  penetrating said case through holes  205 B and engaging threaded holes  205 A in said spring base disk. 
         [0059]    A torsion spring  236  encircles said extension shaft with one end of said torsion spring located in hole  246  in said spring base disk. The opposite end of said torsion spring is inserted in cocking disk  224  through spring retainer hole  246 A. Said cocking disk has a formed slot  234  that fits the flattened surface  242 A of the said partially rounded valve extension shaft. Said partially flattened surface engages the said formed slot of the said cocking disk. Said cocking disk is locked to said valve extension shaft by set screw  232  fitted to threaded hole  260 . A cocking shaft  228  extends through said valve operator case through cocking shaft slot  264  and is installed in said cocking disk for the purpose of rotating said cocking disk through a predetermined arc. 
         [0060]    A depression  230  is formed in said cocking disk surface to harbor a wave spring  222 . Holes  226  of sufficient diameter and depth are formed in said cocking disk for the purpose of engaging locking pins  268  permanently mounted in the piston operating disk  248 . Said piston operating disk includes a piston  216  with two rubber o-rings  214  for the purpose of sealing the piston against the side of the cylinder  212  against gas pressure forced against it but still allowing movement of the said piston within the said cylinder. The said piston operating disk contains four follower channels  220  which engage piston guide screeds  258  which are internal too and a part of the valve operator case  272  which allows the said piston operating disk to move both up and down but restricts any rotating movement. 
         [0061]    Said piston fits within a cylinder  212  which is part of a top piece  206  which rests against the top of said piston guide screeds and with detent  210  fitting inside said piston guide screeds. The said top piece also includes a hose barb or connector  208  which receives and passes pressurized gas to said cylinder  212 . 
         [0062]    Said top piece is held within the said valve operator case by a cap  202  which fits over the top of said valve operator case and is secured by screws  204  inserted through holes  204 B which fit into threaded holes  204 A of said valve operator case. Said cap also includes a hole  270  for accommodating the protruding said hose barb or connector  208 . 
         [0063]      FIG. 4E  and  FIG. 4D  perspective drawings portray the valve operating mechanism without the valve operator case  272  and the valve adaptor ring  266  is shown by dotted lines to expose the said valve extension shaft engaging the said valve stem.  FIG. 4E  displays the gas valve  254  in the closed position with no gas pressure on the cylinder  212  and the piston  216  attached to the piston operating disk  248  is in its most relaxed position urged by the wave spring  222  pressing on the upper surface of the cocking disk  224  and said piston operating disk under surface. The torsion spring  236  applies sufficient force in a clockwise direction as viewed from above to forestall any movement. The cocking shaft  228  is restrained in any further clockwise movement by the cocking shaft slot  264   FIG. 4C . 
         [0064]    When sufficient gas pressure is supplied to the hose barb or connector  208  by the control unit  100   FIG. 2  the gas is induced within the cylinder  212  and urges the piston to move against and overcoming the opposing force of the wave spring  222 . The said piston operating disk  248  can only move in a downward direction restrained from any lateral movement by the piston guide screeds  258  sliding within the follower channels  220  of the said piston operating disk. Pressure is then placed on locking pins  268  projecting from said piston operating disk pressing against the smooth top surface of the said cocking disk. When the said cocking shaft  228  is manually urged in a 90 degree arc counter clockwise as viewed from above the said locking pins will find and drop into recesses  226  engaging the attached said piston operating disk to follow thereby causing the said cocking disk to be restrained in a locked non rotating condition. Since the said valve extension shaft  242  is attached to the said cocking disk and therefore the said gas valve operator shaft valve stem  256  the gas valve is then locked open to allow passage of the heating gas to the said stove. 
         [0065]    Release of the gas pressure supplied to the said cylinder  212  will then cause the said piston operating disk to be retracted by the urging of said wave spring thereby separating the said locking pins of the said piston operating disk from the said recesses  226  thereby releasing said cocking disk and urging the said valve to be closed by the stored energy of the torsion spring  236 . 
         [0066]    The fire protection system of this invention can utilize a multitude of conventional thermally actuated spray heads of several vendors to be selected according to the space to be covered with the fire suppressant. 
       Advantages 
       [0067]    From the description above, a number of advantages of my kitchen type fire protection system become evident and these advantages are: 
         [0068]    (a) the control unit cabinet that houses the suppressant vessel and provides the pressurized fire suppressant does not require extensive installation and can be placed in any number of locations in the near vicinity of the protected area. This unit provides a means of checking the system prior to placing the system in service; 
         [0069]    (b) the system can be installed in instances either with or without a range hood; 
         [0070]    (c) all components will be out of the view of persons near the stove except for one or more small thermally actuated spray heads. Collection of grease and dust on the operating components is severely minimized in comparison with others. Systems as described earlier have much of their equipment easily seen which detracts from the appearance of the kitchen and the pipes and wires are exposed for the collection of grease and dirt; 
         [0071]    (d) installation of the gas disconnect to the stove to remove the source of the heat to the stove is by simple screw on valve that would be installed after a building code required manual gas cut off valve. Installation of tubing or piping to this device for operation of the disconnect utilizes only a small tube easily installed even to pulling the said tubing or piping inside a wall; 
         [0072]    (e) connection of the thermally activated spray head to the control unit is by means of flexible hose or by piping; 
         [0073]    (f) a very important feature of this invention is that it is continually pressurized and failure of the system such as a leak in the two hoses or piping will cause interruption of the gas to the stove therefore making it fail safe; 
         [0074]    (g) due to the simplicity of the installation the cost of this system for gas stoves should be well within the average home owners&#39; affordability. 
       CONCLUSIONS, RAMIFICATIONS, AND SCOPE 
       [0075]    Thus the reader will see that the fire extinguishing system presented herein provides a highly reliable, easily installed system that can save property and lives. 
         [0076]    While the above description contains much specificity, these should not be construed as limitation on the scope of the invention, but rather as an exemplification of the preferred embodiment thereof. Many other variations are possible. As an example, the system can be installed as a protective system in confined instrument cabinets or in many other such applications where fire and the cut off of gas are imperative. 
         [0077]    The operational design of the equipment as presented herein is the presently preferred embodiments and variations of the basic designs might well result in future cost savings. As example, the cocking mechanism of the gas valve could be changed to a ratchet type mechanism or the unit could be self restoring upon the resumption of the pressurized propelling gas of the extinguishing system. However, the simplicity of installation and the fail safe nature of the system are the main attributes. 
         [0078]    Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents. 
         [0079]    For all of the above reasons, applicants submit that the specification and claims are now in proper form, and that the claims all define patentability over the prior art. Therefore they submit that this application is now in condition for allowance, which action they respectfully solicit.