Abstract:
A pressure relief valve for structure. A valve with a spoiler around its edge sits in a valve seat around a structure valve aperture, and is spring-loaded into a closed position. Storm wind entering the structure through a breached window, door, or other structure opening escapes through the valve, which opens when exposed to a pressure differential of approximately 1.5 psi. Lift created by storm wind impinging on the spoiler tends to urge the upwind side of the valve closed. The valve may incorporate a skylight. In the preferred embodiment, the shape of the valve was a spherical or spheroid section, and the spring-loading was provided by a plurality of spring assemblies disposed around the edge(s) of the valve.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates to structures, and in particular to a pressure relief valve for structure. 
         [0003]    2. Background of the Invention 
         [0004]    A common destruction sequence for building structures during windstorms such as hurricanes and tornadoes involves the following steps: 1. An opening such as a window or door is blown in on the upwind side of the structure; 2. The pressure of the air inside the building rises due to strong wind entering the breached opening; and 3. The internal air pressure literally blows the roof off of the structure. In the case of a tornado, the building actually explodes due to the sudden pressure differential of air trapped inside vs. the greatly reduced air pressure outdoors as the tornado approaches closely. 
         [0005]    In this scenario, severe building damage results, clearly from the loss of the roof itself, but also from the ensuing water damage caused by the frequently torrential rain which falls directly into the structure. The problem of wind damage to buildings will probably get worse in the future, due to the natural hurricane cycle, which is currently on the ascendancy, and also due to increased storm strength due to global warning. 
         [0006]    Thus, it would be desirable to provide a means of relieving the internal pressure of structures during wind storms, so as to avoid blowing their roofs off. 
         [0007]    Existing Designs 
         [0008]    A number of approaches have been hazarded to address this problem. U.S. Pat. No. 6,484,459 was granted Platts for a counter-pressure method which involved installing a number of window and door valves to relieve interior pressure. While this approach apparently relieved inside pressure, it was cumbersome to install the requisite valves at various locations in the structure to be protected, was very slow for tornados, and lacked the very high quality flow required for timely pressure equalization. 
         [0009]    U.S. Pat. No. 7,001,266 was granted Jones et al. for a rooftop vent, which was designed to reduce inside pressure. This vent was permanently open, and appeared to suffer from the disadvantage that rain could enter the structure, given sufficient wind. 
         [0010]    U.S. Pat. Nos. 6,206,774, 6,558,251 and 6,293,862 issued to Dexter et al., Sells and Jafine et al. respectively, for roof vents. While these designs appeared capable of relieving pressure internal to a building, no means for doing so on the down-wind side was taught, because these valves could not change their angle relative to the roof upon which they were mounted. 
       SUMMARY OF THE INVENTION 
       [0011]    Accordingly, it is an object of the present invention to provide a pressure relief valve for structure which is capable of instantly relieving windstorm-induced pressure interior to a structure. Design features allowing this object to be accomplished include a plurality of springs urging a valve into a valve seat, the springs being sized to permit the valve to open when a pre-determined pressure differential between air pressure exterior to the structure and air pressure interior to the structure has been reached, e.g. 1.5 pounds per square inch (“psi”). Benefits associated with the accomplishment of this object include reduction of the possibility of the roof being blown off the structure due to windstorm-induced pressure interior to a structure, and the attendant cost savings in repair. 
         [0012]    It is another object of the present invention to provide a pressure relief valve for structure which is normally closed. Design features allowing this object to be accomplished include a plurality of springs urging a valve into a valve seat. Advantages associated with the accomplishment of this object include reduced entry of precipitation, and reduced attendant water damage to the structure. 
         [0013]    It is still another object of this invention to provide a pressure relief valve for structure whose up-wind side will tend to remain closed while its down-wind side opens to relieve pressure interior to a structure. Design features enabling the accomplishment of this object include a valve having spoiler along its edge(s), which spoils the smooth airflow like ice on an airplane wing destroys lift, thus causing the storm wind itself to urge the valve upwind side to remain closed. 
         [0014]    Advantages associated with the realization of this object include less entry of wind-driven precipitation into the structure (because the valve opens for only seconds in a tornado), and the associated reduced water damage and lower cost of repair. 
         [0015]    It is another object of the present invention to provide a pressure relief valve for structure which may be installed in a single location. Design features allowing this object to be accomplished include a valve seat disposed around a building valve aperture, and a plurality of springs urging a valve into the valve seat. Benefits associated with the accomplishment of this object include instantaneous speed, simpler and lest costly installation, better reliability, and reduced maintenance cost. 
         [0016]    It is still another object of this invention to provide a pressure relief valve for structure which may be secured in place using a single cable. Design features enabling the accomplishment of this object include a single cable entering and exiting a valve seat and valve through a plurality of springs. Advantages associated with the realization of this object include simpler construction, along with the associated reduction in cost. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The invention, together with the other objects, features, aspects and advantages thereof will be more clearly understood from the following in conjunction with the accompanying drawings. 
           [0018]    Five sheets of drawings are provided. Sheet one contains  FIGS. 1 and 2 . Sheet two contains  FIGS. 3 and 4 . Sheet three contains  FIGS. 5 and 6 . Sheet four contains  FIGS. 7 and 8 . Sheet five contains  FIGS. 9 and 10 . 
           [0019]      FIG. 1  is a side isometric view of a pressure relief valve mounted at the top of a structure. 
           [0020]      FIG. 2  is a side isometric view of a pressure relief valve which has opened to relieve pressure internal to the structure to which it is mounted. 
           [0021]      FIG. 3  is a side cross-sectional view of a closed pressure relief valve mounted to a structure. 
           [0022]      FIG. 4  is a side cross-sectional view of a pressure relief valve which has opened to relieve pressure internal to the structure to which it is mounted. 
           [0023]      FIG. 5  is a side cross-sectional view of the spring-loaded mounting of a pressure relief valve in the closed position. 
           [0024]      FIG. 6  is a side cross-sectional view of the spring-loaded mounting of a pressure relief valve in another open position, such as may occur in the presence of an approaching tornado due to pressure differential. 
           [0025]      FIG. 7  is a side cross-sectional view of the spring-loaded mounting of a pressure relief valve in an open position, such as may occur when wind increases and the pressure differential has mostly subsided. 
           [0026]      FIG. 8  is a side cross-sectional view of an alternate embodiment spring-loaded mounting of a pressure relief valve in the closed position. 
           [0027]      FIG. 9  is a detail side cross-sectional view of the spring-loaded mounting of a pressure relief valve in the closed position. 
           [0028]      FIG. 10  is a detail side cross-sectional view of the spring-loaded mounting of a pressure relief valve in an open position. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0029]    Referring now to  FIG. 1 , we observe a side isometric view of a pressure relief valve  2  mounted at the top of structure  4 . Structure  4  comprises door  6  and windows  8 .  FIG. 2  is a side isometric view of valve  2  which has opened to relieve air pressure internal to structure  4 . As may be observed in  FIG. 2 , valve  2  seats in valve seat  3 , which is disposed around structure valve aperture  7 . Spoiler  15  is disposed around the edge of valve  2 . Unless opened by internal pressure within structure  4 , valve  2  is normally spring-loaded, and/or urged by gravity, into the closed position depicted in  FIG. 1 . In the preferred embodiment, an internal structure pressure of as little as 1.5 pounds per square inch (psi) sufficed to open valve  2 . 
         [0030]    Referring now to  FIG. 2 , storm wind  14  has breached a window  8  such as may occur during a hurricane, and is now blowing into structure  4  via broken window  10 . Valve  2  has opened against its spring-loaded mounting as indicated by arrow  16 , and is permitting escaping air  18  to exit structure  4  through structure valve aperture  7 , thus avoiding over-pressurization of structure  4 , and its possible catastrophic failure. When pressure internal to structure  4  caused by storm wind  14  has subsided, valve  2  returns to its closed position depicted in  FIG. 1  under the urging of its spring-loaded mounting and/or gravity. Although the figures depict the breach in structure  4  occurring through broken window  10 , valve  2  will function regardless of where the breach occurs, e.g. in door  6 . 
         [0031]      FIG. 2  also depicts an alternate embodiment valve  2  which incorporates skylight  12 . Skylight  12  serves to permit ambient illumination to enter structure  4 , which is often important given the heavy darkness and frequent electrical power outages (shutting off the lights) which accompany hurricanes and tornadoes. 
         [0032]      FIG. 3  is a side cross-sectional view of a closed pressure relief valve  2  mounted to structure  4 .  FIG. 4  is a side cross-sectional view of a pressure relief valve  2  which has opened to relieve pressure internal to structure  4 . Storm wind  14  not only enters structure  4  via broken window  10 , but storm wind  14  also impinges on the upwind side of valve  2 , as may be observed in  FIGS. 3 and 4 . Pressure exerted by storm wind  14  on the upwind edge of valve  2  tends to keep the upwind edge of valve  2  seated, so that only the downwind edge of valve  2  opens due to pressure internal to structure  4 , as depicted by arrow  20  in  FIG. 4 . This situation is also depicted in  FIG. 7 , a side cross-sectional view of the spring-loaded mounting of valve  2  in an open position. The act of valve  2  opening as indicated by arrow  20  in  FIG. 4  permits escaping air  18  to exit structure  4 , thus avoiding its over pressurization. 
         [0033]    Spoiler  15  is disposed around the edge of valve  2 , and serves to spoil the smooth airflow, like ice on an airplane wing destroys lift, thus causing the storm wind itself to urge the upwind side of valve  2  to remain closed. In  FIGS. 3 and 7  we observe smooth storm wind  14  impinging on spoiler  15 , which disturbs the smooth air flow and turns it into turbulent air flow  17 . Turbulent air flow  17  exerts much less lift on the upwind edge of valve  2  than smooth air flow, thus helping keep the upwind edge of valve  2  down. Expressed differently, spoiler  15  disposed along the upwind edge of valve  2  helps keep the upwind side of valve  2  closed. 
         [0034]    Although in the preferred embodiment the cross-sectional shape of spoiler  15  was round, as depicted in FIGS.  1  and  3 - 8 , it is intended to fall within the scope of this embodiment that spoiler  15  be any appropriately shaped spoiler disposed around the edge of valve  2 . 
         [0035]    Even if the upwind side of valve  2  were to rise, thereby admitting storm wind  14 , the downwind side of valve  2  would open (or remain open), thereby allowing storm wind  14  to escape structure  4  as escaping air  18 . In this case, valve  2  would elevate above valve seat  3  as indicated by arrow  28  in  FIG. 6 , and spindles  26  would prevent valve  2  from blowing off structure  4 . 
         [0036]      FIG. 5  is a side cross-sectional view of the spring-loaded mounting of pressure relief valve  2  in the closed position.  FIG. 6  is a side cross-sectional view of the spring-loaded mounting of pressure relief valve  2  in an open position.  FIGS. 9 and 10  are detail side cross-sectional views of the spring mounting of valve  2  on structure  4 . Referring to these figures, valve  2  is spring-bloodedly mounted to structure  4  by means of a plurality of spring assemblies  9  disposed around structure valve aperture  7 . Valve  2  seats in valve seat  3 , which is disposed around structure valve aperture  7 . 
         [0037]    As may be more clearly observed in  FIGS. 9 and 10 , spring assembly  9  comprises a spindle  26  slidably inserted through a valve spindle aperture  38 , a corresponding structure spindle aperture  36 , and a spring  22  disposed inside structure  4 . Spindle stop  40  is attached to an upper end of spindle  26 . Spindle stop  40  is sized to be larger than valve spindle aperture  38 , thus preventing the end of spindle  26  to which spindle stop  40  is attached from sliding through valve spindle aperture  38 . 
         [0038]    Spring  22  is sandwiched between spring stop  24  at a lower end of spindle  26 , and structure  4 . Spring  22  may be pre-loaded so as to urge valve  2  into contact with valve seat  3 , as indicated by arrow  42  in  FIG. 9 . In the preferred embodiment, springs  22  were installed with sufficient compression so as to require a pressure differential of approximately 1.5±1 psi to open valve  2 . In an alternative embodiment, the weight of valve  2  keeps valve  2  closed, and springs  22  may be installed without any compressive pre-load, but rather serve to resist the opening of valve  2 , and to return it to a closed position after internal pressure in structure  4  subsides. 
         [0039]    An alternate embodiment could place spring  22  between spindle stop  40  and valve  2 , in which case spring stop  24  would be sized to be larger than structure spindle aperture  36 , thus preventing the end of spindle  26  to which spring stop  24  is attached from sliding through structure spindle aperture  36 . Spindle  26  could be any appropriate elongate member, including but not limited to cable, chain, a metal or synthetic rod, a bolt, etc. 
         [0040]      FIG. 8  is a side cross-sectional view of an alternate embodiment spring-loaded mounting of a pressure relief valve  2  in the closed position. In this embodiment, spindle  26  is one long elongate member, such as cable  32 , which threads in and out of structure  4  through successive sets of structure spindle apertures  36  and corresponding valve spindle apertures  38 . Cable stops  33  prevent spindle  26  from sliding through valve spindle apertures  38  and springs  22 . Washers  35  could be disposed between cable stops  33  and springs  22 , thus sandwiching each spring  22  between structure  4  and a cable stop  33 . 
         [0041]    In the preferred embodiment, spring assemblies  9  were spaced  12  inches apart. Valve  2  was made of aluminum, metal, synthetic, concrete, or other appropriate material, and skylight  12  was made of glass, plastic, or other appropriate transparent material. Spindles  26  were any appropriate elongate member, including but not limited to cable, chain, a metal or synthetic rod, bolt, etc. Springs  22  were commercially available compression springs. Cable stops  33  and washers  35  were commercially available components. Spindle stops  40  and spring stops  24  were metal, synthetic, or other appropriate material. 
         [0042]    While a preferred embodiment of the invention has been illustrated herein, it is to be understood that changes and variations may be made by those skilled in the art without departing from the spirit of the appending claims. 
       DRAWING ITEM INDEX 
       [0000]    
       
           2  valve 
           3  valve seat 
           4  structure 
           6  door 
           7  structure valve aperture 
           8  window 
           9  spring assembly 
           10  broken window 
           12  skylight 
           14  storm wind 
           15  spoiler 
           16  arrow 
           17  turbulent airflow 
           18  escaping air 
           20  arrow 
           22  spring 
           24  spring stop 
           26  spindle 
           28  arrow 
           32  cable 
           33  cable stop 
           35  washer 
           36  structure spindle aperture 
           38  valve spindle aperture 
           40  spindle stop 
           42  arrow