Abstract:
A device and method for filtering storm water entering a street curb inlet drain using a series of expandable brackets to deploy and seal a filter medium completely inside a street curb inlet drain.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority date of U.S. Provisional 61/271,976 filed on Jul. 29, 2009. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to a street curb inlet filter, and more particularly to a street curb inlet filter for filtering out dirt and other contaminants from flowing into a street curb inlet. 
     Water flowing into a street curb drain carries erosion, leaves, grass clipping, floatable, and assorted trash into the drain, often clogging the storm sewer lines and allowing unwanted contamination into downstream creeks, rivers, lakes, aquifers, reservoirs, canals, or the sea. The environmental damage and financial costs of clean up from storm drains is enormous. 
     Debris and pollutants in runoff water are relatively heavy at construction sites, so sandbags are typically piled around a curb drain inlet as a filter. However, although sandbags block large debris, they impede water flow and do not effectively filter the flow. 
     Numerous solutions have been proposed to solve this problem. Straw wattles and hay bales have been used to filter out sediment and other solids flowing into a street curb inlet storm drain. Additionally, stones have been wrapped in chicken wire and placed in front of a street curb inlet type storm drain. The straw wattle and hay bail type of sediment filters often get clogged and are often not reusable. Also, they may decompose and slip into the storm drain. This could cause further clogging. Furthermore, the method using stones and chicken wire (stone bundles) does not filter out as large amount of sediment and other solids as do other methods. Also, these stone bundles break and fall into the drains, and can also be a safety hazard for children. 
     More sophisticated street curb inlet filter shave been proposed. Fleischmann (U.S. Pat. No. 6,974,540) describes a curb drain filter comprised of U-shaped brackets for attaching to an inside wall of a street curb drain adjacent an inlet. This approach has an internal supported debris basin with a filter media pack to collect debris. Kelly (U.S. Pat. No. 7,357,861) describes a street curb inlet filter with a filter body which includes a, substantially rigid, elongated frame and an elongated filter cover formed around at least one of the sides of the frame, wherein the filter cover is formed of a filtration material to filter out sediments and the like. Hurst (U.S. Pat. No. 7,438,802) describes a storm drain filter that includes a filter panel with a frame that holds a bristle filter in a configuration to filter incoming drainage water. The bristle filter includes a plurality of bristles arranged approximately perpendicular to the street surface. The bristles are arranged closely together to filter sediment from drainage water. The assembly protrudes partially out of the inlet and thus needs to be rotated out of the way during street cleaning. 
     These prior art attempts have often not been adopted by municipalities primarily because of their complexity, degree of difficulty in installation, their need for ongoing maintenance, and in some cases the difficulty of street cleaning unless the inlet protection device is first removed. 
     What is needed then is a more rigorous and easier to install and use inlet protection device, that effectively filters all of the drain water, is relatively hidden from view and does not require frequent maintenance nor removal for street cleaning. 
     BRIEF SUMMARY OF THE INVENTION 
     This need is met with a new inlet protection device that uses simple mechanical brackets and filter material to capture all dirt and debris before it enters a storm water inlet. This is accomplished by use of a bracket structure that applies uniform pressure against the structure inside of the street curb inlet to create a seal. 
     The need is met with an expandable street curb inlet filter for filtering debris flowing into a street curb inlet having a top and a base, including at least: a rigid frame strut having a first guided sleeve pivotally attached on a first end and rigidly connected at a second end to a first extended rod; a rigid compression strut pivotally connected at a first end at a point between the first and second end of the rigid frame strut and fixedly connected at its second end to a second extended rod; a second guided sleeve pivotally attached between the first end and the second end of the rigid compression strut; the second guided sleeve fixedly attached to a threaded nut; a threaded fastener passing through the first guided sleeve and the threaded nut of the second guided sleeve; a filter medium attached fixedly between the first and second extended rods; wherein the threaded fastener, when tightened, moves the rigid compression strut upwards in a reverse scissor movement to separate the first and second extended rods and deploy the filter medium and seal the first and second rods against the top and base of the street curb inlet. 
     In another aspect the need is met with an expandable curb inlet filter for filtering debris flowing into a street curb inlet having a top and a base, including at least: a rigid frame strut having a first guided sleeve pivotally attached on a first end and fixedly connected at a second end to a first extended rod; a rigid compression strut pivotally connected at a first end at a point between the first and second end of the rigid frame strut and fixedly connected at its second end to a second extended rod; a second guided sleeve pivotally attached between the first end and the second end of the rigid compression strut; a threaded turnbuckle assembly connected to the first guided sleeve and the second guided sleeve; a filter medium attached fixedly between the first and second extended rods; wherein the threaded turnbuckle assembly, when tightened, moves the rigid compression strut upwards in a reverse scissor movement to separate the first and second extended rods and deploy the filter medium and seal the first and second rods against the top and base of the street curb inlet. 
     In another aspect the need is met with an expandable street curb inlet filter for filtering debris flowing into a street curb inlet having a top and a base, including at least: a rigid frame strut having a first guided sleeve pivotally attached on a first end and rigidly connected at a second end to a first extended rod; the first guided sleeve fixedly attached to a threaded nut; a rigid compression strut pivotally connected at a first end at a point between the first and second end of the rigid frame strut and fixedly connected at its second end to a second extended rod; a second guided sleeve pivotally attached between the first end and the second end of the rigid compression strut; a threaded fastener passing through the second guided sleeve and the threaded nut of the first guided sleeve; a filter medium attached fixedly between the first and second extended rods; wherein the threaded fastener, when tightened, moves the rigid compression strut upwards in a reverse scissor movement to separate the first and second extended rods and deploy the filter medium and seal the first and second rods against the top and base of the street curb inlet. 
     In another aspect the need is met by a method for filtering debris flowing into a street curb inlet having a top and a base, including at least the steps of: providing a rigid frame strut having a first guided sleeve pivotally attached on a first end and fixedly connected at a second end to a first extended rod; providing a rigid compression strut pivotally connected at a first end at a point between the first and second end of the rigid frame strut and fixedly connected at its second end to a second extended rod; providing a second guided sleeve pivotally attached between the first end and the second end of the rigid compression strut; providing a filter medium attached fixedly between the first and second extended rods; providing a driving force that moves the rigid compression strut upwards in a reverse scissor movement to separate the first and second extended rods and deploy the filter medium and seal the first and second rods against the top and base of the street curb inlet. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an overall view of an embodiment of the expandable street curb inlet filter. 
         FIG. 2  illustrates an embodiment of an individual bracket of the expandable street curb inlet filter. 
         FIG. 3  illustrates another embodiment of an individual bracket of the expandable street curb inlet filter. 
         FIG. 4  illustrates an overall view of an embodiment of the expandable street curb inlet filter shown without the filter medium and elastomeric sleeves. 
         FIG. 5  is an overall view of an alternate embodiment of the expandable street curb inlet filter. 
         FIG. 6  illustrates another embodiment of an individual bracket of the expandable street curb inlet filter. 
         FIG. 7  illustrates an embodiment of an expandable street curb inlet filter deployed in a street curb inlet. 
         FIG. 8  illustrates an alternate embodiment of an expandable street curb inlet filter deployed in a street curb inlet. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A street curb inlet filter of the described invention is shown generally by the numeral  100  in  FIG. 1 . A filter medium  112  is attached between extended rods  102  and  104 . The filter medium  112  can be held in place by a surrounding elastomeric sleeve ( 111  on rod  104  and  109  on rod  102 ). The filter medium can be any material suitable for filtering, depending on the application. For example a useful medium is landscape fabric—a synthetic fabric made from plastic fiber such as polypropylene. Alternately a wire mesh fabric can be used as the filter medium. Rods  102  and  104  may be circular cylinders or other shapes, and can be metal or hardened polymer. Elastomeric sleeves  111  and  109  may be as simple as a rubber hose that is cut with a lengthwise slit to fit around rods  102  and  104 , but could be other elastomeric materials. Shown in  FIG. 1  and in more detail in  FIG. 2  are two expander brackets  140  and  150  that serve as a mechanism to implement the function of the street curb inlet filter. A rigid frame strut  101  has a guided sleeve  107  pivotally connected near a first end and is fixedly connected at the second end to extended rod  102 . Guided sleeve  107  could be as simple as an eyebolt but could be other configurations that allow a threaded fastener  105 , such as a threaded bolt to feed through it. A structure  106  to which threaded fastener  105  tightens against could be as simple as a washer or could be designed as a part of guided sleeve  107 . A rigid compression strut  103  is pivotally connected at a first end at a point between the first and second end of rigid frame strut  101  and is fixedly connected at its second end to extended rod  104 . A second guided sleeve  108  is pivotally attached between the first and second ends of rigid strut  103  and has a fixed threaded nut  113  through which threaded fastener  105  can be tightened. 
     In operation street curb inlet filter  100  can be easily inserted into a street curb inlet in a collapsed mode and then the threaded fasteners  105  can be tightened with an appropriate tool, or by hand, pulling compression strut  103  upwards in a reverse scissor movement, spreading the assembly until it is locked into place in the street curb inlet, with rods  102  and  104  sealing off against the top  121  and bottom  120  of the street curb inlet. The inlet filter  100  is placed into the street curb inlet behind the face  122  of the curb so that no part of the system protrudes past the face  122  of the street curb inlet. When the torque force on threaded fastener  105  is set properly the street curb inlet filter  100  can withstand the force of incoming water and accompanying debris. 
     The street curb inlet filter of  FIG. 1  is shown with only two expander brackets ( 140  and  150 ). In practice street curb inlet filter  100  may be much longer and have multiple expander brackets. It has been found that expander brackets approximately every 12 inches provides a good design choice for robust operation. 
     A number of design options exist for providing the driving force for expanding the brackets  140  and  150  of  FIG. 1 . An alternate embodiment is shown in  FIG. 3  in which instead of the threaded fastener  105  and threaded nut  109  combination of  FIG. 2  a similar compression force could be obtained by replacing the threaded fastener of  FIG. 2  with a center turnbuckle  209  coupled to two threaded rods  210  and  211  pivotally attached at  207  and  208 . Any of these threaded fastener options are anticipated as part of this invention. Turnbuckle  209  has left hand screw threads on one end and right hand screw threads on the other so that simply turning turnbuckle  209  will apply the necessary force to pull the compression strut upwards in a reverse scissor movement until it locks the street curb inlet filter in place in the street curb inlet in the same way as the design in  FIG. 2 . The invention of this disclosure anticipates any threaded fastener (or turnbuckle) that can perform this function of expanding the brackets to seal the street curb inlet filter against the top  121  and bottom  120  of the street curb inlet. 
     Brackets  140  and  150  could also be expanded without the use of threaded fasteners by the use of installed springs (not shown) that provide the force for expanding the brackets in order to lock the street curb inlet filter into place. In that aspect the street curb inlet filter would be inserted into the street curb inlet with the springs compressed and once properly placed the springs would be released to expand brackets  140  and  150  and lock the street curb inlet filter into place. 
       FIG. 4  is an alternate view of  FIG. 1  with filter medium  112  and elastomeric sleeves  109  and  111  have been removed to illustrate the brackets better. Struts  101  and  103  are shown attached to extended rods  104  and  102  and fixed with welds  401  and  403 . Similar welds are sown at  402  and  404 . Other design choices could be used to fixedly attach the struts to the extended rods and they are anticipated by this invention. 
       FIGS. 1-4  show one aspect of configuring the threaded fasteners. In another aspect the orientation of the threaded fastener bolts  105  can be changed to face in the opposite direction to achieve the same functional results.  FIG. 5  shows such an orientation. In this embodiment the orientation of the street curb inlet filter can be reversed so that the filter medium is facing outward to the street and the bolts are hidden.  FIG. 6  illustrates an individual bracket for this configuration in more detail. 
     The actual deployment of these alternate views are illustrated in  FIGS. 7 and 8  in which  FIG. 7  illustrates the deployment  400  of the  FIG. 5  embodiment. The inlet filter is deployed inside the face  420  of curb inlet  440 .  FIG. 8  illustrates the deployment  800  of the  FIG. 1  embodiment. The inlet filter is again deployed inside the face  420  of curb inlet  440 . 
     The expandable street curb inlet filter as illustrated in  FIGS. 1  thru  8  and described above can be easily inserted into a street curb inlet and simply tightened into a rigid configuration and provide robust filtering of incoming water and do so with no part of the mechanism extending out into the street—thus avoiding the common problem of prior art systems of being dislodged by street cleaning equipment or creating safety hazards to passersby. 
     While the present invention has been described in some detail, according to the preferred embodiments illustrated above, it is not meant to be limiting to modifications such as would be obvious to those skilled in the art.