Patent Publication Number: US-8980084-B2

Title: Filter assembly for use in drainage system

Description:
TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION 
     The present invention relates to filter assemblies for use in drainage systems to prevent the buildup of eroded materials such as soil, leaves and other debris within the drainage system. The assembly includes a unitary frame and a filter media attached to the frame. The assembly is adapted to be retained within a component of a drainage sewer such as a catch basin. The frame is inserted into an inlet to the drainage system such as a gutter inlet and is supported within the inlet. The filter media is formed of a porous material such as a woven or non-woven geotextile to allow for the flow of water through the filter while retaining debris or other materials within the filter. The filter media extends into the basin to provide volume for the retained material without blocking the entire surface of filter. 
     BACKGROUND OF THE INVENTION 
     Typical drainage systems collect surface water within underground drainage systems to prevent flooding. In a typical drainage system a number of inlets are connected to an underground storm sewer system. An inlet typically includes a removable cast iron grate that inhibits the flow of some large debris into the inlet. The grate may include openings of up to four inches or longer and allows the flow of debris into the drainage system. The debris builds up within the drainage system and will block the flow of water through the system and may cause localized flooding. In order to maintain the flow of water it is necessary to clean the drainage system. This cleaning is typically performed with a great deal of physical effort and a truck equipped with a vacuum hose to remove the debris from the system. 
     It is known to place a filtering screen above or below the storm drain grate to collect smaller items of debris that may pass through the grate. These prior art filters are easily blocked by a buildup of debris or soil on the filter. Complicated structures have been developed to allow an increased sump area for collection of debris within the catch basin. These structures require rings or hooks that penetrate and weaken the filter media. Another prior art device, as shown in U.S. Pat. No. 6,294,095, includes a frame that is inserted into the drainage system and a number of rods that are fitted to and retained by the frame to retain the filter media. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention relates to filter assemblies for use in a drainage system to prevent the buildup of eroded materials such as soil, leaves and other debris in the system. The assembly includes a unitary frame and a filter media attached to the frame. The frame is inserted into an inlet to the system such as a gutter inlet and is supported within the inlet. The filter media is formed of a porous material such as a woven or non-woven geotextile to allow for the flow of water through the filter while retaining the eroded materials within the filter. The filter media extends into the inlet to provide volume for the retained material without blocking the entire surface of the filter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  shows a perspective view of a frame in accordance with the present invention. 
         FIG. 2  shows a perspective view of a frame and filter media in accordance with the present invention. 
         FIG. 3  shows an exploded perspective view of the system shown in  FIG. 2 , including a drainage grate and frame. 
         FIG. 4  shows the system of  FIG. 3  installed in a curb. 
         FIG. 5  shows an exploded perspective view of an alternative system according to the present invention, including a curb and gutter drainage grate and frame. 
         FIG. 6  shows a cross-sectional view of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE INVENTION 
     U.S. application Ser. No. 11/700,597 filed Jan. 31, 2007 is hereby incorporated by reference. 
     With respect to the figures,  FIG. 1  shows a frame suitable for use in the filter assembly of the present invention. The frame may be of any shape and is configured to fit within an inlet to a drainage system. The frame  12 , as shown, includes frame members  12   a ,  12   b ,  12   c  and  12   d  and welds  14   a ,  14   b ,  14   c  and  14   d  to form a rectangular frame. Other suitable frames may be square, round, oblong or any other shape to match the drainage system inlet. One suitable material for use in forming the frame is ½″ by ⅛″ steel. The use of steel provides a rigid frame that inhibits bending when a loaded filter element is removed from a drainage system and is easily fabricated by welding. Any material that provides suitable strength, and can be fabricated to the desired shape, may be used. 
     As shown in  FIG. 2 , system  10  generally includes a frame  12  and filter media  16 , which allows water to flow through the filter media  16  while collecting debris. The system includes a sump area, in which debris is collected, formed by the filter media  16  and frame  12 . The filter media  16  is preferably connected to the frame by one or more pockets sewn into the filter area. As shown in  FIG. 2 , pockets  18   a ,  18   b ,  18   c  and  18   d  encompass the frame members  12   a ,  12   b ,  12   c  and  12   d  (shown in  FIG. 1 ). In the event of a round frame (not shown) one or more pockets are used. The pockets are preferably formed by doubling the filter material over around the upper edge of the filter material and sewing the double layer to form the pocket. The pocket is generally formed prior to insertion of the frame into the pocket and a final weld is performed after the system  10  is assembled. It is also possible to form the frame and sew the filter media to the frame. The use of sewn pockets rather than the hooks or bolts of the prior art allows for increased strength, improved reliability and easier use in the field. 
     The assembly  10  may also include webbing  20  extending across the filter for supporting the weight of the debris within the sump, and loops  22  of webbing  20  that extend above the frame  12  to aid in lifting the filter assembly from a drainage system. In a preferred embodiment, the filter is a woven geotextile material with a water flow rate greater than about 100 gallons/minute/ft 2  and preferably has a water flow rate greater than about 145 gallons/minute/ft 2 . The assembly  10  may include corner cutouts  24  to allow overflow in the event that the sump area of filter  16  is completely filled. 
     One suitable filter media is TerraTex EP-12, woven geotextile available from WebTec, LLC of Charlotte, N.C. The TerraTex EP-12 has a tensile strength of 365/2001b (ASTM D-4632); a puncture strength of 90 lb (ASTM D-4833) and a water flow rate of 145 gallons/minute/ft 2  (ASTM D-4491). A suitable webbing is a 2″ polypropylene webbing available from Tape Craft of Oxford Alabama, which has a tensile strength of 1050 lbs. When manufactured using TerraTex EP-12, woven geotextile and 2″ polypropylene webbing an assembly  10  having a length of 16″ and width of 35″ will hold over 600 lb of wet soil without failure. 
       FIG. 3  shows an assembly  10  of the present invention suitable for installation in a curb drain  50 . The drain  50  includes a flange  56  configured to be placed on top of a catch basin (not shown), a peripheral side wall  58  and supports  60  to strengthen the side wall  58 , and a bonnet  66  above overflow  64 . On the interior of the side wall  58  is a protrusion or detent  62  that supports grate  52 . The filter assembly  10  is inserted into drain  50  so that frame  12  rests on detent  62  and grate  52  is placed above the frame. An L-bracket  54  may be placed on the grate to inhibit the flow of debris into overflow  64 . 
       FIG. 4  shows an assembly  10  in a curb drain  50 . The drain  50  is fixed in curb  66  with flange  56  place on top of a catch basin (not shown), the peripheral side wall  58  and supports  60  are positioned beneath road level while bonnet  66  and overflow  64  are above the road and within the curb  66 . The filter assembly  10  is inserted into drain  50  and grate  52  is placed above the frame. An L-bracket  54  is shown on the grate  52  to inhibit the flow of debris into overflow  64 . 
       FIG. 5  shows an assembly  10  of the present invention suitable for installation in a curb and gutter drain  50 . The drain  50  is configured to match a rolled curb so that frame  12  is non-planar and matches the shape of the grate  82 . It may also be preferable to include an additional frame member  12   e . The additional frame member  12   e  allows for the filter assembly to allow overflow directly to the catch basin (not shown). Similar to  FIG. 3 , the drain  50  includes a flange  56  configured to be placed on top of a catch basin (not shown), a peripheral side wall  88  and supports  90  to strengthen the side wall  88 . The grate  82  matches the shape of the curb so a bonnet, as shown in  FIG. 3 , is unnecessary. The uppermost row of orifices in the grate  82  serves as the overflow for the system. The additional frame member  12   e  allows unrestricted flow of water from the grate  82  to the catch basin (not shown) in the event that the assembly  10  is filled. A protrusion or detent  62  supports grate  82  and matches the curvature of the grate. The filter assembly  10  is inserted into drain  50  so that frame  12  rests on detent  62  and grate  82  is placed above the frame. 
       FIG. 6  shows a cross-section of a drain  50  with flange  56  , a peripheral side wall  58  and supports  60 . The filter assembly  10  is inserted into drain  50  so that frame  12  rests on detent  62  with filter media  16  hanging below drain  50 . The grate  52  and an L-bracket  54  are inserted into the side wall  58  so that tabs  54   a  are pinched between grate  52  and peripheral side wall  58 . It is preferred that the tabs  54   a  are set in from the end of L-bracket  54  by at least ⅜″ so that the edges of the L-bracket extend to the bonnet (as shown in  FIG. 4 ). 
     The invention of this application has been described above both generically and with regard to specific embodiments. Although the invention has been set forth in what is believed to be the preferred embodiments, a wide variety of alternatives known to those of skill in the art can be selected within the generic disclosure. The invention is not otherwise limited, except for the recitation of the claims set forth below.