Patent Publication Number: US-9849321-B2

Title: Concealed sprinkler activation

Description:
BACKGROUND OF THE INVENTION 
     The invention relates generally to a fire suppression systems and, more particularly, to a concealed fire suppression sprinkler having a more efficient activation. 
     Fire suppression systems typically include sprinklers positioned strategically within an area where fire protection is desired. The sprinklers remain inactive most of the time. Even though the sprinklers are inactive, many systems include fire suppression fluid within the conduits that supply the sprinklers. The fluid is pressurized and it is necessary to maintain an adequate seal to prevent any leaks at the sprinklers while they are inactive. 
     In some instances, the sprinklers in a fire suppression system may be concealed. Concealed sprinklers are usually covered by a cover plate which is substantially flush with a ceiling in which the sprinkler is mounted. The cover plate is soldered in place such that in the presence of a fire, heat and combustion gasses flow through a small gap between the cover plate and the ceiling. The high temperature melts the solder causing the cover plate to separate from the sprinkler and expose the activator bulb. Because the activator bulb is initially concealed by the cover plate, the flow of combustion gasses to the activator bulb is restricted until the cover plate is removed, thereby delaying the activation of the sprinkler. 
     BRIEF DESCRIPTION OF THE INVENTION 
     According to one embodiment of the invention, a fire suppression sprinkler assembly coupled to a mounting surface includes a sprinkler having a heat responsive element arranged adjacent a first end. A cover plate is positioned adjacent the heat responsive element and includes a thermally conductive cover layer. A reflective shield has a reflective interior surface. The reflective shield is positioned substantially opposite the cover plate adjacent the first end of the sprinkler such that heat reflects from the top plate towards the heat responsive element. 
     According to another aspect of the invention, a method of activating a fire suppression sprinkler is provided including heating a cover layer coupled to a cover plate located adjacent a first end of the sprinkler. Heat from the cover layer is then transmitted to a top plate positioned opposite the cover plate. Heat reflects from the top plate toward a heat responsive element positioned adjacent the first end of the sprinkler such that the heat responsive element activates the sprinkler 
     According to yet another aspect of the invention, a fire suppression sprinkler assembly coupled to a mounting surface is provided including a sprinkler having a heat responsive element arranged adjacent a first end. A cover plate is positioned adjacent the heat responsive element. The cover plate includes a plurality of holes through which heat and gas reach the heat responsive element such that the cover plate is thermally semi-transparent. 
     According to yet another aspect of the invention, a method of activating a fire suppression sprinkler is provided including heating a thermally semi-transparent cover plate. Heat from the cover plate is transmitted to the air formed within a cavity of the cover plate. The heated air within the cavity is channeled to a heat responsive element located at a first end of the sprinkler such that the heat responsive element activates the sprinkler. 
     According to another aspect of the invention, a fire suppression sprinkler assembly coupled to a mounting surface is provided including a sprinkler having a heat responsive element arranged adjacent a first end. A cover plate including a plurality of openings is positioned adjacent the heat responsive element such that the cover plate surrounds a portion of the heat responsive element. A top plate is positioned generally opposite the cover plate to substantially enclose the heat responsive element. At least one of the cover plate and top plate is configured to direct heat toward the heat responsive element. 
     These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a cross-section of an exemplary portion of a fire suppression sprinkler assembly; 
         FIG. 2  is a cross-section of a fire suppression sprinkler assembly according to an embodiment of the invention; 
         FIG. 3  is a cross-section of a fire suppression sprinkler assembly according to an embodiment of the invention; 
         FIG. 4  is a perspective view of an exemplary portion of a fire suppression sprinkler assembly; 
         FIG. 5  is a top view of a cover plate of a fire suppression sprinkler assembly according to an embodiment of the invention; 
         FIG. 6  is a perspective view of a cover plate and top plate of a fire suppression sprinkler assembly according to an embodiment of the invention; 
         FIG. 7  is a cross-section of the cover plate and top plate illustrated in  FIG. 6 ; 
         FIG. 8  is a cross-section of a top plate according to an embodiment of the invention; 
         FIG. 9  is a perspective view of a fire suppression sprinkler assembly according to an embodiment of the invention; and 
         FIG. 10  is a perspective view of another fire suppression sprinkler assembly according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to  FIG. 1 , a portion of a fire suppression sprinkler assembly  10  is illustrated. The fire suppression sprinkler assembly  10  includes a fire suppression sprinkler  20  configured to discharge a mist of fire suppression fluid, such as water for example. The sprinkler  20  includes a housing  22  that establishes a flow path  24  through at least a portion of the housing  22 . For example, the sprinkler housing  22  may include a plurality of channels  26  extending from the center of the sprinkler  20  outwards, such that the fire suppression fluid will be discharged through these channels  26  to outside the sprinkler  20 . Disposed within the center of the sprinkler  20  is a water seat  30  movable between an inactive and an active position. When the water seat  30 , and therefore the sprinkler  20 , is in an inactive state, the water seat  30  is configured to close off the flow path  24 . An activator bulb or other heat responsive element  40 , disposed vertically between the water seat  30  and an adjustment member  42  located at a first end  21  of the sprinkler  20 , retains the water seat  30  in an inactive position. The activator bulb  40  operates in a known manner for maintaining the sprinkler  20  in an inactive condition under most circumstances. When experiencing an elevated temperature, such as in the presence of a fire for example, a fluid within the activator bulb  40  expands, causing the bulb to break, and thereby allowing the sprinkler  20  to transition to an active, operating state in a known manner. The fire suppression sprinkler assembly  10  may include other types of fire suppression sprinklers, for example sprinklers  20  having an activator bulb  40  in a horizontal configuration. An exemplary horizontal activator bulb  40  is illustrated in  FIG. 2 . Though the illustrated sprinkler  20  is a compressive activator bulb  40 , alternate configurations, such as a tensile activator bulb for example, are within the scope of the invention. Fire suppression sprinklers  20  having an activator bulb  40  arranged in a horizontal configuration function in substantially the same manner as the fire suppression sprinklers  20  having a vertically oriented activator bulb  40  as described above. 
     The fire suppression sprinkler  20  may be mounted to a portion of a building, ship, or other structure, such as to a ceiling for example. Referring now to  FIGS. 2 through 7 , exemplary fire suppression sprinkler assemblies  10  also include a cover plate  100  mounted adjacent the first end  21  of a sprinkler  20 . A top surface  102  of the cover plate  100  connects to an adjacent mounting surface  80  using fasteners, adhesive, or other known connection means. The mounting surface  80  may be a ceiling, or alternatively, may be a portion of a trim can for example. The cover plate  100  is generally concave, such that the first end  21  of the sprinkler  20 , including the activator bulb  40 , is disposed within a cavity  104  of the cover plate  100  below the plane of mounting surface  80 . In one embodiment, the cover plate  100  includes at least one arm  106  for supporting an end of the activator bulb  40 . As illustrated in  FIG. 4 , the cover plate  100  may include a first arm  106   a  configured to support a first end  44  of the activator bulb  40  and a second arm  106   b  configured to engage the second opposite end  46  of the bulb  40 . A separate cover layer  120  may be disposed about the exterior of the cover plate  100  ( FIGS. 3 and 10 ). In one embodiment, the cover layer  120  is made from a lightweight metallic material, such as a foil for example. The exterior surface of either the cover plate  100  or the cover layer  120  may be painted the same color as the mounting surface  80  so that the fire suppression sprinkler assembly  10  is integrally formed with its surroundings in an aesthetically pleasing manner such that no apparent shadow line exists. 
     The cover plate  100  may be manufactured from plastic or another durable material. In one non-limiting embodiment, the cover plate  100  is formed from a thermally and/or visually semi-transparent material. The cover plate  100  includes a plurality of openings  108  that allow heat to transfer into the cavity  104  toward the activator bulb  40  or allow a fire suppression fluid to be discharged outside of the cavity  104 . For example, holes or slots  108  may cover in the range of about 25 percent to about 75 percent of the surface area of the cover plate  100 . In one embodiment, the plurality of openings  108  may be arranged generally perpendicular to the airflow adjacent surface  80 , to increase the activation time of the sprinkler  20 . The cover plate  100  may additionally include a plurality of heat features  110  configured to channel heat towards the activator bulb  40  positioned at the center of the cavity  104 . The heat features  110 , such as ribs for example, protrude inwardly or outwardly from a surface of the cover plate  100  and may have a substantially constant thickness or a variable thickness along the length of each heat feature  110 . The plurality of heat features  110  may be identical or may be dissimilar. As illustrated in  FIG. 5 , the heat features  110  may curve generally radially outwardly from the center of the cover plate  100  or alternatively may be straight. 
     Referring now to  FIGS. 6-8 , a top plate  140  including a central opening  144  through which a first end  21  of the sprinkler  20  is received may be used in conjunction with the cover plate  100 . A portion of the top plate  140  has a diameter substantially equal to the diameter of the cavity  104  adjacent the top surface  102  of the cover plate  100 . In one embodiment, the top plate  140  is mounted to a surface opposite the cover plate  100  (see  FIG. 9 ). In another embodiment, the top plate  140  is supported by a portion of the cover plate  100 , such as through a snap-fit connection for example (see  FIG. 10 ). The top plate  140  traps heat within the cavity  104  adjacent the activator bulb  40 . In one embodiment, the top plate  140  may be a generally flat disc having a uniform thickness, as shown in  FIG. 7 , or alternatively may include a partially angled bottom surface  141  that facilitates the flow of hot air toward the activator bulb  40  ( FIG. 8 ). The top plate  140  may be formed separately from the cover plate  100  or may be integrally formed with the cover plate  100 , such as through an injection molding process for example. 
     When a fire is present, and the cover plate  100  does not include a cover layer  120 , the heat and combustion gasses generated by the flames enter into the cavity  104  through the plurality of openings  108  in the cover plate  100 . Inclusion of the top plate  140  prevents the heat and gasses from rising away from the first end  21  of the sprinkler  20 . The semi-transparent cover plate  100  is heated through convection from the rising heat and gas. In turn, heat from the cover plate  100  radiates to the air within the cavity  104 . In embodiments where the cover plate  100  includes a plurality of heat features  110 , the heat features  110  will channel the heat and gas flowing into the cavity  104  directly toward the activator bulb  40 . 
     In another embodiment, illustrated in  FIGS. 9 and 10 , the top plate  140  of the fire suppression sprinkler assembly  10  is generally convex and defines a cavity  142  such that the first end  21  of the sprinkler  20  may be disposed therein. The cavity  142  of the top plate  140  adjoins the cavity  102  of the cover plate  100  to create a larger cavity  160  within which the entire first end  21  of the sprinkler  20  is located. In the illustrated embodiment, the interior surface  146  of the top plate  140  is reflective to redirect heat within the cavity  142 . In one embodiment, the interior surface  146  is made from a foil, such as aluminum foil for example. The top plate  140  may also include a plastic, exterior shell  148  such that the foil forms a lining on the interior of the shell  148 . The plastic shell  148  retains the mirror-like interior surface  146  in a desired shape. In one embodiment, the top plate  140  is generally parabolic in shape and has a height such that the activator bulb  40  of the sprinkler  20  is located at the focus of the top plate  140 . 
     When a fire is present and the cover plate  100  includes a cover layer  120 , the heat and combustion gasses generated by the flames will heat the cover layer  120 . As the temperature of the cover layer  120  increases, heat is released into the cavity  160  via infrared radiation. By including multiple openings  108  in the cover plate  100 , the area of the cover layer  120  that transfers heat to the cavity  160  may be maximized. Because the cover layer  120  is thin and has a large surface area, the temperature of the cover layer  120  rapidly increases such that the temperature of the cover layer  120  closely follows the temperature of the combustion gasses. When a parabolic top plate  140  having a reflective interior surface  146  is positioned opposite the cover plate  100 , the heat within the cavity  160  radiates to the mirror-like interior surface  146 . Because of the parabolic shape of the top plate  140  and the positioning of the activator bulb  40  within the cavity  160 , heat energy reflects from the interior surface  146  and is directed to the activator bulb  40  positioned at the focus of the top plate  140 . In this manner, the top plate  140  acts as a reflector, concentrating the radiated heat from the fire toward the activator bulb  40 , to accelerate the activation of the sprinkler  20 . The top plate  140  and the cover layer  120  act as an amplifier, making it possible to increase the temperature of the activator bulb  40  without heating the air within the cavity  160  to a temperature at least equal to the bulb activation temperature. 
     Once activated, the pressure of the fire suppression fluid may break through the cover layer  120  adjacent the openings  104  in the cover plate  100 . Alternatively, at least a portion of the sprinkler  20  may move relative to the ceiling. In one embodiment, the sprinkler  20  applies a force to the cover plate  100  such that the first end  21  of the sprinkler  20  is exposed. For example, the In an alternate embodiment, the first end  21  of the sprinkler may penetrate through the central hole of the cover plate  100  and through the cover layer  120  such that cover layer does not block the emission of fire suppression fluid. 
     By locating the cover plate  100  and top plate  140  adjacent the first end  21  of the sprinkler  20 , the heat generated by a fire is focused directly at the activator bulb  40 . By concentrating heat energy at the bulb  40 , the time required for the fluid inside the bulb  40  to expand and break the bulb  40  is minimized. Consequently, the sprinklers are activated more quickly in the presence of a fire, allowing the fire to be suppressed or extinguished more rapidly. Use of a cover plate  100  and top plate  140  to hasten the activation of a sprinkler  20  is not limited to water mist applications, and may be used on any type of sprinkler  20  actuated by an activator bulb  40 . In addition, because direct contact with the heat and combustion gasses is not required to activate the sprinkler  20  when a top plate  140  having a reflective interior surface  146  is used, in some instances the sprinkler assembly  10  may be mounted in a manner such that no gaps exist between the cover plate  100  and the mounting surface. This mounting method prevents dust and other particles from building up on the activator bulb  40 , reducing the maintenance of the sprinkler assembly  10 . 
     While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.