Abstract:
A lightweight watertight cover that is easily installed and positively secured in place, which provides a reliable seal to prevent flood water from entering openings such as subway ventilation shaft gratings and other porous openings that serve as entry point for flood water.

Description:
FIELD OF INVENTION 
     The present invention relates to a portable flexible sealing device that prevents water or other fluids from entering an underground shaft, pipe, or building through openings which are covered by non-water tight gratings. The invention can be used to prevent unwanted flooding into subways, buildings, storm water systems, and other facilities from tidal storm surges, heavy rain events, water main breaks, etc. The invention could also provide facility or personnel protection from hazardous waste spills or from chemical, biological and/or radiological attacks. This invention provides a reliable cover device and method to render the grated opening watertight in the presence of inches to tens of feet of fluid head pressure, and is securely fastened to prevent the cover device being removed by wind, water action or vandalism. 
     PRIOR ART 
     There are prior patents that (WO 2009091599 A1, U.S. Pat. Nos. 6,530,722 B1, 7,887,257 B2) that provide a device to seal holes, but do not include a mechanical system to ensure a positive seal while under wind and/or water loading. Another patent (U.S. Pat. No. 7,879,233 B2) provides details of a vent cover, but its functionality is geared towards filtering unwanted solid matter or debris from entering storm drains, but not preventing the entry of storm water. Another patent (WO 2005075757 A1) is based on a sealing device for drains holes and it relies on filling a center chamber with materials such as sand, metal pellets, etc. to facilitate sealing. Another invention covered in U.S. 7,950,075 B2 described a sealing device based on use of flexible polymeric materials, but it does not include a provision to actively apply force to ensure a water tight seal around drain openings and secure the device in place. 
     BACKGROUND OF INVENTION 
     The economic impacts of flood damage are a serious issue around the world. The cost of flood damage is increasing and projected to increase further as the impacts of global climate change are realized. Sea level rise as well as the greater intensity of storms inland have the potential to increase the frequency of flooding in coastal, as well as inland regions. The need for flood mitigation solutions that are quickly applied and effective against all threats witnessed in storms are needed. These devices must not only seal openings against shallow water events, but must also withstand many feet of hydrostatic pressure, and in some cases, withstand loads from hurricane force winds and moving water, and even be tamperproof against vandalism. The portable flexible sealing device of the invention has been created to fill this need. 
     One example of an immediate need is the protection of subway systems. Subways have ventilation (or vent) shafts which generally open at street level and are covered by rigid metal, or composite, gratings. The subway systems are equipped with pumps and drainage systems that are able to prevent flooding during typical storms. However, many cities are located near bodies of water and are becoming increasingly vulnerable to sea level rise from climate change and from tidal or storm surges. For example, in 2012, Hurricane Sandy caused billions of dollars of flood damage to New York City subway infrastructure due to the storm surge. Although there are many routes of entry for fluids to find their way into a subway system, the vent shafts have been identified as a major source. The portable flexible sealing device of the invention was created to quickly seal subway vent shafts prior to a storm to prevent flooding. Plywood sheets were installed ahead of Hurricane Sandy to prevent water from getting in through vent shafts. However, they were not effective. Several alternative approaches like raising vent shaft entrances above sea level to reduce flooding of tunnels due to storm run-off and rain water are being explored. However, these approaches require changes to the existing vent shafts covers and could prove very expensive, and are not often acceptable to a city&#39;s architectural or historical preservation needs. 
     In addition to coastal transit systems being at risk, climate change has also increased the intensity of storms and rainfall which cause flash flooding. Inland cities and towns all over the world have experienced flooding events which have allowed water to penetrate transit systems, commercial and industrial buildings, and other properties through ventilation, wastewater and other ducting or connecting shafts/pipes. Grated openings come in many forms and can be in numerous orientations, so sealing devices need to be adaptable in size, shape, and effects of gravity. 
     SUMMARY OF INVENTION 
     The invention pertains to a sealing device, or cover, for preventing or minimizing the entry of water or other fluids into underground areas, or areas below flood level such as building interiors, that are connected to the surface via an opening that is covered by a grating or a grille. The sealing device can be used to seal openings that are in horizontal, vertical, or in-between orientations relative to ground level. The sealing device functions by sealing the perimeter of the opening being covered via a pliable material that acts as a water tight seal by being compressed against the area surrounding the grating cover. 
     The sealing device is comprised of a unique segmented assembly of rigid plates encapsulated by a coated fabric that allow it to adapt to irregular surfaces, fit into corners to seal in two planes simultaneously, and be collapsible for transport and storage. The device is a planar structure that can be designed in varying geometrical shapes including rectangular, square, curved and rounded configurations, and has hinge points that enable it to bend and seal openings that are not planer. The main structural components of the sealing device include an arrangement of rigid panels, a flexible membrane that sandwich the rigid panels and make the cover impervious to fluids, anchor assemblies that attach the cover to the grating, rigid ribs that act as a fulcrum, and a pliable perimeter seal on the underside of the cover. The fundamental principle of operation of this device that sets it apart from other flat plate sealing devices is the use of a fulcrum and lever system to exert pressure on the watertight gasket around the grating opening. The rigid plates extend from the perimeter of the cover to the fulcrum, or typically one-third to one-half the distance from the edge of the cover to the center of the cover, but the distance can be scaled to fit any situation. Therefore, the central portion of the cover is only the coated fabric or membrane material, and as such greatly reduces the weight of the assembly. 
     The anchor assemblies provide a method of securely fastening the cover to the grating, and in conjunction with the fulcrum create a lever function that focuses clamping force onto the perimeter seal. Each rigid section has a fulcrum that rests against the interior portion of the grating. The holes on the cover assembly that receive the fasteners used to attach the cover to the grate are large enough to facilitate insertion of the fastener through an available opening in the grate. The heads of the fasteners are equipped with a gasket that seals the hole around its perimeter when the fastener is tightened to the grate. The fastener itself resembles a large bolt with a hook at its end. When it is inserted into the hole in the cover the hook catches the bottom of the grate as the bolt is tightened, and the cover is secured in place. 
     The rigid panels are arranged such that there are gaps or spaces between these panels along the plane of arrangement. These rigid panels are encapsulated between layers of flexible coated textile material which is intimately adhered to either side of the rigid panels. Since the rigid panels are tightly sandwiched between two flexible layers, they form an integrated cover with hinges that are both stiff for sealing and flexible for adapting to surface geometries. The gaps between the plates also reduces the torsional rigidity of the rigid planar structure and maximizes the clamping force on the gasket seal around the perimeter, as well as creating an independent series of perimeter seal compression systems so that the clamping force on the seal will be consistent even if the surface geometry of the grating is not planer. This is important because the land around many grated structures shifts over time and the gratings and their perimeter support features become undulated. This is readily apparent in cities where earth settling or tree roots cause sidewalks with gratings to crack and move out of plane. Without the segmentation of the rigid stiffeners in the cover, the cover would act as a single flat plate that would contact one portion of the grating before the others and negate the ability to put compressive pressure on the seal, and would therefore leak. 
     The gaps between the rigid panels are supported only by the flexible top and bottom layers and therefore act as hinges. This design ensures control over the location of the hinges. In one of the embodiments for large-area covers, larger gaps in the strategic locations of the cover are incorporated to make the cover foldable for compact storage and easy handling or transportation. 
     The grate sealing device can be sized to fit any grated opening with a solid surrounding feature such as a rim, with a single device. The device can also be abutted in multiple units to seal non-standard or larger openings that are covered by grating or grilles. This limits the number of different sizes required and simplifies installation by creating universal designs. The sealing of openings that are larger than the size of the vent cover can be achieved by using multiple vents covers in conjunction to the surface area of the opening and by using transitional pieces of impermeable gasket material between the vent covers to seal the area of abutment. The transitional gasket between covers is clamped in place under the perimeter seal on the cover to provide a water-tight join between covers. 
     The grate sealing device is sufficiently conformal to the grating and to uneven topological surfaces at the edge of the opening at the sealing interface around the device&#39;s outer perimeter to allow for a water tight seal. To allow for the grate sealing device to be easily hand carried to the point of use, it is made from lightweight materials including a combination of flexible coated textiles or membranes, rigid composite or metal plates, and flexible gasket materials in the form of foams or extrusions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates the side view of the vent cover with anchors in position before installation. 
         FIG. 2  shows the schematic of the anchor in vent cover. 
         FIG. 3  shows the view from the bottom in relation to the installed position of the vent cover. 
         FIG. 4  shows the top view of the vent cover with anchors in position for installation. 
         FIG. 5  shows the cross-sectional view of a vent cover installed over a grating of vent opening. 
         FIG. 6  shows the position of the anchors with hook engages with the grating of vent opening. 
         FIG. 7  shows the vent cover in a folded configuration without the anchors. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows the side view of one embodiment of the vent cover. in this embodiment, the vent cover is rectangular in shape with all of its components including the rigid laminate  101 , anchor assembly  102 , rigid rib  301  at the fulcrum point, and the compressive gasket seal  103  that is attached at in a continuous line around the edges of the rigid laminate to create a barrier for entry of liquid media and other contaminants against which a seal is desired. The vent cover has two sides in relation to its installation and function. The side of the vent cover that has the anchor plate  201  is the top side and the side which has the gasket seal  103  and rigid rib  301  is the bottom side of the vent cover. 
       FIG. 2  shows a perspective view of an embodiment of the anchor assembly. The anchor plate  201  is connected to the bolt  206 . In this embodiment a holding pin  202  is attached into the anchor plate to facilitate positioning the anchor assembly between the bars of gratings or grilles  210 , but it is not necessary to the function of the anchor assembly and can be left out, The anchor plate  201  is positioned between the gasket seal  103  and the rigid rib  301 , which acts as the fulcrum point on the vent cover. In this embodiment, the anchor plate  201  has a layer of compressive material  203  underneath that acts as a seal for the anchor assembly when inserted into the hole in the rigid laminate. This anchor plate  201  and compressive material  203  together perform the functions of evenly distributing the force from clamping of the anchor plate against the top surface of the vent cover and also acts as a seal against water during flooding. This layer is held in place in the intended position of the anchor assembly by a retainer ring  204 . The section of the anchor assembly that has screw threads  206  to facilitate the bolting of the anchor assembly also has a hook  205  and a termination feature  207  to prevent the hook from accidently sliding from the anchor assembly. 
       FIG. 3  shows the bottom view of the vent cover. The rigid rib  301  is positioned at an optimum distance from the fastener insertion hole in the cover with the objective to transferring maximum force to the gasket  103  when the fastener is tightened, which is directly linked to how effective the gasket seal is in minimizing the entry of water through the grated opening. 
       FIG. 4  shows show the top view of the vent cover with a location of the anchor assembly represented by the anchor plates. 
       FIG. 5  shows the cross-section view of the cover in its installed position over the grating. The hooks are positioned and locked against the bars of the grating. 
       FIG. 6  shows the close-up view of the hooks in the anchor assembly locked in with the grating bars. 
       FIG. 7  shows the vent cover folded at the center to allow for easy transportation and installation.