Abstract:
An initiator with fuse device for an automatic self-contained fire suppressor and method are provided herein. Stovetop fires are a well-known residential and commercial hazard. The initiator with fuse device for an automatic stovetop fire suppressor has a rapid light time in the presence of flames. The time to light is consistent and reliable for the fuse described herein. Comparative tests show a shorter light time for the present fuse as compared to conventional fuses. Further, the variability in lighting times is shortened when the herein described configuration is employed. Deployment of an automatic stovetop fire suppressor can be safer than manual extinguishing means and via the initiator with fuse described herein, the time to deployment is greatly improved. Manufacturing of the initiator with fuse is readily adapted to existing processes.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application No. 61/803,045, filed 18 Mar. 2013, the entire contents of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a device and method of fire suppression, and more particularly to initiating an automatic stovetop fire suppressor. 
     BACKGROUND OF THE INVENTION 
     Stovetop fires are a well-known residential and commercial hazard. An unattended stovetop fire, for example a grease fire, can cause damage to nearby appliances and cabinets. Worse, stovetop fires can lead to structural damage or injury. Because the propensity for stovetop fires is so pervasive, an efficient means of automatic fire suppression is desired. Even if a stovetop fire is attended, an automatic extinguishing method may be more effective, safe, and expedient compared to manual means. 
     A number of conventional automatic stovetop fire extinguishers, which mount above the stovetop surface, are available. These include: U.S. Pat. No. 6,276,461 to Stager: U.S. Pat. No. 6,105,677 to Stager; U.S. Pat. No. 5,899,278 to Mikulec; U.S. Pat. No. 7,472,758 to Stevens and Weintraub; U.S. Pat. No. 7,610,966 to Weintraub et al; U.S. Pat. No. 5,518,075 to Williams; and U.S. Pat. No. 3,884,307 to Williams. The array of conventional fire suppression systems vary from activation by melting of a fusible pin (Stager &#39;461), to melting a solder fusible plug (Stager &#39;677), to burning of a fuse (Williams &#39;307, Stevens &#39;758), or to activating via a glass bulb fuse mechanism (Mikulec). The mounting mechanism for these systems similarly vary from interconnected tubing (Mikulec) to pendulum anchors (Stager &#39;461), to bolts (Stager &#39;677), or to magnetic systems requiring assembly (Williams &#39;307 and Williams &#39;075). 
     Conventional fire suppresors, STOVETOP FIRESTOP® fire suppressor (Williams-Pyro, Inc., Fort Worth, Tex., USA), which are particularly well suited to a stovetop environment, include a container of an extinguishing agent mounted to a vent hood above the stovetop and activated by a fuse. An example of such an suppressor is shown in  FIG. 1 . The bottom of the container contains a fuse. A fire on the stovetop ignites the fuse, which in turn detonates an igniter. The igniter opens the bottom of the container, thereby allowing the disbursement of the extinguishing agent onto the fire and the stovetop. In the example shown in  FIG. 1 , the container is secured via a magnet to a hood over the stove. 
     A conventional initiator comprising a fuse is shown in greater detail in  FIG. 2 . The conventional initiator is further described below with reference to  FIG. 2 . The conventional fuse assembly is effective at heat activating the initiator cup; however, a shortened activation time with excellent reproducibility of the same for a stovetop fire suppressor would be desirable for reasons to include safety and damage to surrounding structures and figures. 
     SUMMARY OF THE INVENTION 
     The present invention addresses some of the issues presented above by providing a new fuse for heat activation of the initiator in an automatic stovetop fire extinguisher Embodiments of the present invention may have any of the aspects below. 
     One aspect of the present invention is to provide an efficient heat activation apparatus for a stovetop fire suppressor. 
     Another aspect of the present invention is to provide an improved consistency in heat activation time for an automated stovetop fire suppressor. 
     Another aspect of the present invention is to provide a minimal time of heat activation time for an automated stovetop fire. 
     Another aspect of the present invention is to provide a fast lighting fuse in the presence of flames in a stovetop fire suppressor. 
     Another aspect of the present invention is to provide a minimal time of heat activation time for an automated stovetop fire suppressor with minimal additional manufacturing steps. 
     Yet another aspect of the present invention is to provide very low variability in heat activation time for an automated stovetop fire suppressor while shortening the time to fuse ignition for a given flame exposure. 
     Still another aspect of the present invention is to provide a method of making a fuse that yields a consistent fuse lighting time. 
     Those skilled in the art will further appreciate the above-noted features and advantages of the invention together with other important aspects thereof upon reading the detailed description that follows in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       For more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures, wherein: 
         FIG. 1  shows a cross sectional view of a conventional stovetop fire suppressor for mounting under a vent-hood above a stove top surface along its axial center with a partial cross section of the mounting magnet; 
         FIG. 2  shows a cross section of a conventional initiator and heat activated fuse in greater detail; 
         FIG. 3  shows a graphical representation of experimental data testing the activation times of conventional fuses in an automatic stovetop fire suppressor; 
         FIG. 4  shows a cross section of an initiator and heat activated angle cut fuse in greater detail, in accordance with an exemplary embodiment of the present invention; 
         FIG. 5  shows a graphical representation of experimental data testing the activation times of angle cut fuses, in accordance with exemplary embodiments of the present invention; 
         FIG. 6  shows an exemplary method of making a fuse for an automatic stovetop fire suppressor container, in accordance with an exemplary embodiment of the present invention; 
         FIG. 7  shows an exemplary method of making an initiator with fuse for an automatic stovetop suppressor, in accordance with an exemplary embodiment of the present invention; and 
         FIGS. 8A and 8B  show a bottom view of an outside of a container lid and cross section of the lid as taken along line  8   ba - 8   b , respectively, in accordance with an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention, as defined by the claims, may be better understood by reference to the following detailed description. The description is meant to be read with reference to the figures contained herein. This detailed description relates to examples of the claimed subject matter for illustrative purposes, and is in no way meant to limit the scope of the invention. The specific aspects and embodiments discussed herein are illustrative of ways to make and use the invention, and are not intended to limit the scope of the invention. Same reference numbers across figures refer to like elements for ease of reference. Reference numbers may also be unique to a respective figure or embodiment. 
       FIG. 1  shows a cross section of a conventional stovetop fire suppressor for mounting under a vent-hood  100  above a stove top surface along the axial center of the device. Within magnet housing  54  the partial cross section shows magnet  51 . Magnet  51  is ring shaped and has a center hole  52 . The surface  50  attaches to, for example, a vent hood to correctly position the stovetop fire suppressor for activation when needed. Mounting ring  57  threads through magnet housing loop  59  at one end and through the clevis pin  56  eye  53  on another end. Clevis pin  56  passes through an opening in the top  48  of the fire suppressor container  40 . The fire suppressor container  40  is filled with a fire suppressant powder  49 , which is conventionally a powder. Clevis pin  56  has a shoulder  52  and a felt washer  58  is sandwiched between shoulder  52  and an inside of the top  48  of the container  40 . A retaining ring  55  secures the clevis pin  56  in the position shown in  FIG. 1 . A conventional initiator  30  comprises an initiator cap  32  and an initiator cup  34 . The initiator  30  is secured to the container  40  lower lid  20 . Extending from outside the lid  20  of the container  40  and into the initiator  30  is fuse  10 . Conventionally, the fuse  10  has a straight end cut, as shown. 
       FIG. 2  shows a cross section of a conventional initiator  30  with fuse mounted to a lid  20  in greater detail. Conventional methods of forming an suppressor initiator include attaching the cup to the lid. Referring to  FIG. 2 , the initiator forming is further described. For example, the cup  34  is placed over a lower die in a press/staking machine, the suppressor container lid  20  is placed on top of the cup and then first eyelet  12  is placed in the upper die. The press is activated and the eyelet  12  is driven down through the suppressor lid and initiator cup and formed  12  on the inside of the cup  34  to firmly attach the bottom of the initiator cup  34  and the suppressor container lid  20  together. This first eyelet  12  has a center hole that provides the inlet of the fuse  10  into the initiator cup  34 . 
     A fuse assembly may be created by placing a second eyelet  14  on a pre-cut length of fuse  10 . The fuse is cut perpendicular to the axial orientation  210  of the fuse, and the resulting straight edge fuse  10  is shown in  FIG. 2 . The eyelet  14  is then positioned in place and crimped to attach it to the fuse  10 . The fuse assembly is then inserted through the hole in the first eyelet  12  from the inside of the initiator cup  32 . A gun powder substitute  36  is then dispensed into the cup/lid/fuse assembly. And finally, a cap  32  is placed on the open end  37  of the cup and the two parts are ultrasonically welded together to form an initiator for a stovetop fire suppressor  30 . 
     We investigated both the lighting times for a conventional fuse type and configuration and the consistency of lighting times for the same conventional fuse types. First, the responsiveness of the conventional fuse configuration with a conventional lacquer was determined experimentally. The test setup included a Bunsen burner and a fuse retaining fixture which left an exposed fuse portion  11  similar to that shown in  FIG. 2 . Each fuse sample was loaded into the fixture and positioned 4.75″ directly above the Bunsen burner flame. The gas supply to the Bunsen burner was held constant. The time to light the fuse was recorded for 10 samples and the condition of lit was determined by visual inspection.  FIG. 3  shows a graphical representation of data acquired by the above described experimental setup and procedures. Samples of the conventional configuration and conventional lacquer (clear 25% nitrocellulose) are represented by A  350 , see legend  375  shown in  FIG. 3 . Conventional fuse types are an American visco fuse with an approximate diameter of 3/32 inches and which are red in color and are lacquer coated off the shelf. (Fireworks International, Virginia Beach, Va., USA). After cutting the fuse to the desired length, conventionally and in accordance with embodiments of the present invention, a coat of lacquer is applied to the external cut end of the fuse to seal it. The conventional lacquer end coat is a clear twenty-five percent nitrocellulose lacquer, for example, an OPEX nitro-cellulose alkyd production lacquer (Sherwin Williams, Cleveland, Ohio, USA). 
     Samples from one to ten were taken for the A  350 , B  340 , C  330  lacquered and non-lacquered D  360  straight cut conventional fuse configurations, where B  340  samples were coated with a green 25% nitrocellulose lacquer, A  350  samples were coated with a 25% concentrated mix of nitrocellulose N-butyl acetate lacquer on the cut end and C  330  samples were coated with a 10% nitrocellulose lacquer (Skylighter, Inc., Round Hill, Virginia, USA) on the cut end and D  360  samples were bare, lacking any lacquer coating coated onto the cut end. In experimental setup and in practice the lacquer may be applied to the exposed and mounted fuse with a commercially available liquid dispenser, excess lacquer can run down to the first eyelet and fuse interface. In accordance with the present invention, alternate coating methods may be employed such as painting by hand or by spraying. The application method employed was consistent across all test samples. 
     The time to fuse lightings  302  are provided in seconds, along the Y axis in seconds  306 . The sample numbers,  1  through  10  are provided on the X axis  304  for the A  350 , B  340 , C  330 , and D  360  fuse types, respectively, for a total of 40 fuses tested. The activation times for each sample were plotted in seconds. Each different fuse type and respective sample was identically mounted and positioned above the Bunsen burner. Conventional fuse types are a visco fuse, which is lacquer coated off the shelf. After cutting the fuse to the desired length, a coat of lacquer is applied to the external cut end of the fuse to seal it. 
     The straight cut fuse sample lighting times varied between two seconds  322  and more than eighty seconds  320 . The variation in lighting times for a given lacquer, A  350 , B  340 , or C  330  varied by at least twenty fold. Even the non-lacquered end cut fuse, D  360 , samples varied more than twenty fold for lighting times across ten samples and reached a lighting time in excess of forty seconds. 
     A conventional visco fuse typically consists of a burning core coated with wax or lacquer for durability and water resistance. A visco fuse typically has a core of black powder with one or more outer wraps of textile about the vertical axis. Further, the outer layers may be coated with wax or nitrocellulose lacquer for water and dirt resistance, and the outer coating may also provide mechanical protection. These fuses burn at a uniform rate, with an easily visible external flame. Depending on the outer coating, visco fuses may be water resistant. 
       FIG. 4  shows a cross section of an initiator  30  and angle cut fuse  10 - 1  in greater detail, in accordance with an exemplary embodiment of the present invention. Fuses are cut to yield a forty five degree angle  10 - 5  with the fuse vertical axis  210 - 1 . In accordance with an exemplary embodiment, the cut process for an angle cut fuse includes placing a long piece of fuse on a horizontal workbench. Holding the fuse against a straight edge, a razor was aligned with a forty five degree mark and the fuse was cut with a razor blade by pressing downward by hand. The blade was held perpendicular to the cutting plane. A protractor was used to measure and confirm a forty five degree angle with respect to the fuse axial length, vertical axis. The resulting angles of the cut fuses were measured with a protractor and all samples tested were within approximately plus or minus three degrees of a forty five degree angle cut. The initiator cup  34 , cap  32 , container lid  20 , first eyelet  12  and second eyelet  14  are consistent with those described above with reference to  FIG. 2 . 
       FIG. 5  shows graphical representation of experimental data testing the activation times  302 - 1  of angle cut fuses, the angle cut  10 - 5  shown in  FIG. 4 , in accordance with exemplary embodiments of the present invention. Samples from one to ten were taken for the A′  550 , B′  540 , and C′  530  lacquered 45 degree angle cut fuse configurations, where A′  550  samples were coated with conventional lacquer (clear 25% nitrocellulose) on the cut end, B′  540  samples were coated with a green 25% nitrocellulose lacquer, 25% concentrated mix of nitrocellulose N-butyl acetate lacquer on the cut end and C  530  samples were coated with a 10% nitrocellulose lacquer (Skylighter, Inc., Round Hill, Virginia, USA). Symbols for the different sample types A′  550 , B′  540 , and C′  530  are summarized in legend  375 ′. The time to fuse lightings are provided in seconds, along the Y axis  306 - 1 . The sample numbers,  1  through  10   304 - 1  are provided on the X axis  304 - 1  for the A′  550 , B′  540 , and C′  530 , cut angle fuses, respectively, for a total of 30 fuses tested. The activation times for each sample were plotted in seconds  306 - 1 . Each different fuse lacquer and respective sample was identically mounted and positioned above the Bunsen burner as described above. 
     The angle cut fuse sample lighting times showed much lower variability and lower average and maximum lighting times. Angle cut fuses varied between less than two seconds to less than 28 seconds. The average lighting times for a given lacquer, A′  550 , B′  540 , and C′  530  was greatly reduced as compared to the straight edge cut fuses, shown in  FIG. 3 . Referring again to  FIG. 5 , average lighting times for the angle cut fuses could be reduced to less than five seconds across 10 samples. In alternate embodiments, different lacquers can be used in accordance with the present invention; all three lacquers tested showed decreased lighting times and decreased variability with the angle-cut end as compared to a straight cut end. 
       FIG. 6  shows a method of making a fuse for an automatic stovetop fire suppressor container, in accordance with an exemplary embodiment of the present invention. Briefly, in production, the fuse can be pulled off of a spool by a set of rollers, fed to length horizontally along the cutting plane and sheared by a vertical cutting blade where the blade is set to a 45 degree angle relative to the axial direction. The angle cut fuse, in accordance with the present invention, changes the orientation of the cutting blade but does not add additional steps to the manufacturing method of making the fuse. A faster and more consistent fuse is obtained in the absence of increased manufacturing time and costs. Referring to  FIG. 6 , acquire spool of fuse  610 , pull fuse off of spool with rollers  612 , and feed along cutting plane to desired fuse length  614 . Position cutting blade perpendicular to cutting plane  616  and further position blade at 45 degree angle from fuse length axis  618 . Shear fuse from spool feed with blade at 45 degree angle to fuse axis and cut perpendicular to cutting plane  622 . And once cut, spray, or otherwise coat, fuse cut end with nitro-cellulose lacquer  626 . In accordance with embodiments of the present invention, coating of the cut end of the fuse may be performed after the fuse is mounted in the initiator. 
       FIG. 7  shows an exemplary method of making an initiator with fuse for an automatic stovetop suppressor, in accordance with an exemplary embodiment of the present invention. A faster and more consistent flame activated initiator for an automatic stovetop fire suppressor is obtained in the absence of increased manufacturing time and costs. 
     A coating of lacquer is then placed on the outside interface of the first eyelet and fuse. This seals the fuse to the eyelet to prevent the gun powder substitute from flowing out at that interface. A coating of lacquer is also placed on the end of the fuse to seal if from the environment  745 . The lacquer to the end cut of the fuse may have already been applied during fuse formation and, in turn, this last coating of lacquer,  745 , would not be needed, in accordance with an exemplary embodiment of the present invention. Referring to  FIG. 7 , place an initiator cup over a lower die in a press/staking machine  710 , place a fire suppressor container lid on a top side of the cup  712 , place a first eyelet in the upper die  714 , and activate press, driving first eyelet down through the lid and cup and forming on the inside of the cup, firmly attaching the pieces together  716 . Provide inlet of the fuse into the initiator capsule through a center hole in the first eyelet  722 . Place a second eyelet on a pre-cut length of fuse  726 . Crimp second eyelet, attaching it to the fuse  731 ; and insert fuse with the crimped second eyelet through an inside of the cup through the inlet and resting the second eyelet atop the first eyelet  733 . At this point the angle cut end of the fuse extends below an outside of the suppressor container lid, as shown for example in  FIG. 4 . Referring again to  FIG. 7 , dispense gun powder substitute into the cup  737 ; place a cap on the top open end of the cup; and ultrasonically weld the cap to the cup  741 . Apply a coating of lacquer to the outside interface of the first eyelet and the fuse  743 , forming an initiator for an automatic stovetop fire suppressor with fuse. In accordance with an exemplary embodiment of the present invention, the lacquer is a nitro-cellulose lacquer. In accordance with another exemplary method embodiment of the present invention, a coating of nitrocellulose lacquer is applied to the angle end cut of the fuse  745 , 
       FIGS. 8A and 8B  show view of an outside of a container lid  20  and cross section of the lid as taken along line  8 B- 8 B, respectively, in accordance with an exemplary embodiment of the present invention. Once assembled, the fuse extends through the lid exposing its cut end past the outside side of the lid, not shown. Referring to  FIG. 8A , the bottom lid  20  has grooves or scored lines  41 A- 46 A selectively formed on the outside thereof to facilitate breaking or rupturing of the bottom end into separate tear-open segments  41 - 46  without fragmentation to form openings  41 B- 46 B, openings not shown, only in the bottom end or bottom wall portion, lid  20 , when the free ends of the segments are forced outward to allow the fire extinguishing powder  49 , shown in  FIG. 1 , to fall or pass outward from the container onto the fire. Although the scoring is illustrated on the outside surface of the lid it can be on the inside surface thereof. The fuse  10 - 1 , shown in  FIG. 4 , ignites when the temperature outside of the fire suppressor reaches a certain level to explode the charge  36 , also shown in  FIG. 4 . When this occurs, the force of the explosion ruptures the scored or weakened lines and forces the tear open segments  41 - 46  outward to form the openings  41 B- 46 B. The fire extinguishing powder then falls out of container  40 , shown in  FIG. 1 , for example, to extinguish any fire below which may be in a frying pan, for example. 
     Still referring to  FIGS. 8A and 8B , the non-erupting portions of the lid  20  is referred to as the web  27 W of the lid  20 . Embossed reinforcing ribs  27 WR are formed in the lid  20  to make the web  27 W stiffer and to assist in minimizing any problem of the segments  41 - 46  or vanes not opening outward. The embossing forms a center circle with radially extending ribs between break open segments  41 - 46 . The ribs  27 WR may be formed by bending the web  27 W outward after the score lines  41 A are formed, which tends to pull metal away from the score lines  41 A- 46 A and may facilitate opening of the segments  41 - 46 . 
     The time between a fire starting on a stove and the fuse on a flame activated automatic stovetop fire extinguishing unit lighting, actuation time, is desired to be as small as possible. The present invention improves fire suppressor actuation time and repeatability of actuation time. Exemplary embodiments include an angle cut fuse end. 
     While specific alternatives to steps of the invention have been described herein, additional alternatives not specifically disclosed but known in the art are intended to fall within the scope of the invention. Thus, it is understood that other applications of the present invention will be apparent to those skilled in the art upon reading the described embodiments and after consideration of the appended drawings.