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CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional patent application Ser. No. 60/889,687 filed on Feb. 13, 2007 and entitled “Trench Grate Assembly With Debris Chute.” 
    
    
     FIELD OF THE INVENTION 
     The present invention is directed to a grate assembly for topping a drainage trench, and more specifically, to a frame for supporting and retaining a grate structure over a drainage trench. 
     BACKGROUND OF THE INVENTION 
     Trenches for directing storm water to subterranean piping are commonly found in paved surfaces such as driveways and parking lots, and are typically found across vehicular entrances and interior surfaces of the pavement. To allow for vehicular travel over the trench, these trenches are typically covered by substantial grates or grating systems and assemblies that are cast into the pavement, for example, concrete. 
     Typical trench grate assemblies include two parts: a frame section that is cast into and retained by the pavement, and a grate section. The frame section comprises a metal component that is positioned over a ledge formed in the pavement when it is cast around the frame along the sides of the trench and is sized and dimensioned to receive a grate, that is usually generally rectangular in shape. The frame can be made up of many frame sections connected end to end to receive many grate sections end to end, so the trench can be quite long. The grate sections are typically fastened to the frame using bolts that extend through holes in the grate sections and are screwed into threaded holes in the frame. 
     Prior grates were sometimes difficult to attach securely to the frame. The threaded holes in the frame were blind holes or if through holes were closed by the concrete or other pavement into which the frame was cast. Debris could collect in the holes and when a bolt being threaded into the hole contacts debris proper tightening of the bolt becomes impossible. Once compressed, the debris could be difficult to remove and so fasteners could be left out or not completely tightened, resulting in a structure less structurally sound than intended, and would allow grates to be easily dislodged by traffic. The present invention addresses these problems. 
     SUMMARY OF THE INVENTION 
     In one aspect, the present invention provides a frame for retaining a trench grate over a drainage trench. The frame includes a substantially vertical support member having a sidewall for alignment along a wall of the drainage trench pavement into which the frame is cast, and a bearing flange extending substantially perpendicular to the sidewall for supporting a grate over the drainage trench, the bearing flange overlying the drainage trench pavement into which the frame is cast. The bearing flange includes at least one aperture for receiving a fastener for coupling the grate to the bearing flange, and a chute that substantially circumscribes an area below the aperture and that includes an opening directed inward toward the trench to direct debris collected through the aperture toward the trench to maintain the aperture in an open condition. 
     In another aspect of the invention, the chute can be angled toward the trench, and can also substantially circumscribe an area below the aperture. The interior of the chute, moreover, can be formed in the shape of compartment open at its front and closed on all other sides except the top into which the fastener hole opens. 
     The chute may, for example, be generally in the shape of a quarter sphere. The frame can also include an anchor element extending from a corner formed between the substantially vertical support member and the bearing flange in a direction away from the trench and into the pavement, to be cast and therefore securely retained in the pavement. The anchor member can include an aperture sized and dimensioned to have a rebar reinforcement rod threaded through it, which is also cast into the pavement for additional securement. 
     In yet another aspect of the invention, a frame for retaining a trench grate over a drainage trench is provided, including a support member extending along a wall of the drainage trench and including a substantially vertical sidewall. A substantially horizontal flange extends from the sidewall of the support member for supporting a grate in the drainage trench. Pavement encapsulates the outer side and bottom surfaces of the support member. A chute extends downward from the support member and is positioned below and substantially surrounding the aperture, which prevents pavement from filling in beneath the hole when the pavement is cast. A side of the chute faces inwardly toward the trench and includes an opening to allow debris received in the chute to be directed into the trench and to prevent debris from gathering in the bottom of the threaded hole. The opening in the chute can include a lower edge that is angled toward the trench. 
     In still another aspect of the invention, a drainage trench is provided, comprising a concrete structure having a bottom surface and first and second substantially parallel sidewalls, with shoulders at the upper ends of the sidewalls. A frame is embedded in the shoulders and includes a vertical support aligned along a side of each of the first and second parallel sidewalls and a substantially horizontal bearing flange extending from each of the vertical supports toward a center of the pavement trench. A grate, including a first plurality of spaced apertures, is received in the frame. A second plurality of spaced apertures is formed in the substantially horizontal bearing flange of the frame, and is configured for alignment with the first plurality of apertures for receiving fasteners to couple the grate to the frame. A chute is formed below each set of aligned apertures that has outer surfaces of its rear, side and bottom walls embedded in the pavement. Each chute includes an opening in its front wall, facing the trench, wherein debris collected in the aligned apertures can fall through the apertures into the chute and through the opening to maintain the apertures open. The inward edge of the opening is preferably in a plane and the plane is coplanar with the inward facing surface of the bearing flange to be sealed by a planar concrete form when concrete is poured around the frame. The chute can be ramped in the direction of the trench, substantially rounded in configuration, or can be shaped substantially as a quarter sphere. 
     Features and characteristics of the present invention will be apparent from the description which follows. In the detailed description below, preferred embodiments of the invention will be described with reference to the accompanying drawings. These embodiments do not represent the full scope of the invention. Rather the invention may be employed in other embodiments, and reference should therefore be made to the claims herein to determine the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top view of a trench assembly including a frame constructed in accordance with the present invention assembled as part of a drainage trench. 
         FIG. 2  is a cutaway side view of the trench assembly taken along the line  2 - 2  of  FIG. 1 . 
         FIG. 3  is a cutaway view of the trench taken along line  3 - 3  of  FIG. 1 . 
         FIG. 4  is a front view of a frame section of  FIG. 1 . 
         FIG. 5  is a bottom view of a frame section of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the Figures and more particularly to  FIG. 1 , a top view of a trench grate assembly  10  constructed in accordance with the present invention is shown, as assembled over a drainage trench. The trench grate assembly  10  generally comprises a frame  14 , constructed from a plurality of frame sections  15  laid end to end, and a plurality of grate sections  16  that are received in the frame  14 . The frame  14  is constructed by aligning frame sections  15  end to end along a concrete form, e.g., sheets of plywood assembled so they create an open topped box, with the front or inward surfaces of the sections  15  against the outer sides of the concrete form, and pouring concrete around the sides of the form and the outside surfaces of the frame sections  15 . The concrete form, made of flat sheets, for example plywood, lays up flat against the front (or inward) surfaces  32  and  49  of the respective chute  26  and bearing flange  28 , which surfaces are flush with one another so as to simultaneously seat against the flat surface. This prevents concrete from flowing into the chute  26  or up over the flange  28 . The form, of course, prevents the concrete from flowing into the form so that when the concrete sets, the form can be removed leaving the open trench bordered at its top margin by the frame sections  15 , with the concrete side walls  51  of the trench substantially flush with the inward surfaces  32  and  49  of the respective chute  26  and flange  28 . 
     Anchors  22  are embedded in the pavement  21  surrounding the trench  12 , and may have steel re-bar threaded through them. The re-bar can be bent in a U or V shape, and the re-bar cast into the concrete along with the anchors  22  for additional holding force. The grate sections  16  are aligned end to end over the drainage trench  12  in the frame  14 , and each includes a plurality of threaded apertures  20 , which receive fasteners  18  in threaded engagement, for retaining the grate sections  16  on the frame  14 . Each fastener  18  is positioned over a debris chute  26 , a portion of the frame  15  that maintains an open area beneath the aperture  20  and fastener  18 , and directs debris from the bolt hole  23  toward the trench  12 . 
     Referring now to  FIG. 2 , a cutaway side view of the trench grate assembly  10  of  FIG. 1  taken along line  2 - 2  is shown. The frame sections  15  each include a substantially vertical member  25  coupled integrally (i.e., cast in one piece) to a horizontal flange  28  that extends along the length of the frame section  15 . A top surface  41  of the vertical member  25  aligns substantially with the top or roadway surface  43  of the pavement  21 , and the outside  27  and bottom  29  surfaces of the section  15  are cast in the concrete or other pavement. The bottom surface  29  is preferably angled downwardly away from the trench so that when the section  15  is driven over, it tends to wedge into the corner formed by the surrounding concrete. The generally horizontal flange  28  is positioned a distance from the top surface of the vertical member  25  selected to allow a grate section  16  to be positioned within the frame  14  with the top surface  45  of the grate section  16  substantially aligned with the top surfaces  41  and  43  of both the frame  14  and the pavement  21 , to provide a substantially continuous roadway surface. Anchor members  22  extend into the pavement  21  and are angled downward and away from the corner formed by the surfaces  27  and  29 . The anchor members  22  each include an aperture sized and dimensioned to receive a rebar reinforcement member, as described above. 
     Referring now to  FIG. 3 , a cross-sectional view of the trench  12  taken along the line  3 - 3  of  FIG. 1  through the debris chute  26  in the frame section  15  is shown. The debris chute  26  is positioned adjacent an aperture  23  in the frame section  15  that is aligned with an aperture  20  in the grate section  16  for receiving a threaded fastener  18  to couple the grate section  16  to the frame section  15 . The debris chute  26  is formed below the bottom surface of the horizontal flange  28  and, referring now also to  FIG. 4 , substantially circumscribes the aligned holes  20  and  23 . An interior surface  33  of the chute  26  is directed toward an opening  31 , and is substantially rounded in cross-section such that a corner between a back wall and a lower surface of the debris chute  26  is curved and sloped toward the opening  31 , forcing dirt and debris collected in the debris chute  26  through the opening  31  and into the trench  12 , to maintain the aperture  23  substantially open. The lip of the lower surface  30  positioned adjacent the trench  12  is also rounded, again to force dirt and debris from the chute  26 . As shown here, the interior surface  33  is shaped as a compartment with a single open side, on its inward side, and the threaded bolt hole  23  opening in its top side. More particularly, the chute  26  is cupped, and may be substantially shaped as a portion of a sphere, and more specifically as a quarter of a sphere-like surface. Referring still to  FIG. 4 , the opening  31  of the debris chute  26 , therefore, is generally a cross section of a sphere and therefore substantially semi-circular in shape, with an upper surface formed by the flange  28 . Concrete or other paving material encapsulates the sides, bottom and back of the chute  26 , and is not over the opening  31 . Opening  31  is defined by edge surface  32  of the chute  26  around the opening  31 . Surface  32  is co-planar with the vertical edge surface  49  at the front of the flange  28 . Being coplanar allows these surfaces  31  and  49  to butt up against the flat side of a concrete form, typically a plywood surface, to prevent concrete from flowing into the chute  26  or up over the flange  28  when the concrete is poured. The concrete sidewalls  51  therefore are cast substantially flush, i.e. substantially co-planar at least where they meet the edges  32  and  49 , with the front edges  32  and  49  of the respective chute  26  and flange  28 . 
     Referring now to  FIG. 5 , a bottom view of the frame section  15  is shown. Debris chutes  26  are located adjacent apertures  23  for receiving a threaded fastener  18 , and include a rounded inner surface substantially closed except at the front opening  31  and top hole  23 , as described above with reference to  FIGS. 4 and 5 . 
     Referring still to  FIG. 5 , the frame section  15  is again shown with anchor members  22 , including apertures  24  sized and dimensioned to receive a rebar reinforcement. The anchor members  22  can couple the frame to wood or other framing members during construction of the trench  12 , for retaining the corresponding frame section  15  in the pavement  21  and anchoring the frame section  15  in position when they are set in cured concrete, particularly if re-bar is threaded through them. 
     Referring again to  FIG. 3 , it can be seen that, after the fastener  18  is removed from apertures  20  and  23 , dirt and debris falling into the aligned apertures  20  and  23  will be directed to the debris chute  26 , thereby preventing the accumulation of debris which could clog the holes  20  and  23 , prevent the insertion of the fastener  18 , and thereby inhibit either assembly or re-assembly of the frame and grate assembly  10 . 
     Although a preferred embodiment of the invention has been described in considerable detail above, many modifications and variations to the preferred embodiment will be apparent to a person of ordinary skill in the art. For example, although the interior of the chute is shown and described as forming a portion of a sphere, the interior surface can be angled toward the drainage trench in various ways, and formed in various shapes useful for directing debris toward the trench. For example, the interior of the chute can be formed as a tube, or ramped or angled, toward the trench in a number of different ways which will allow debris to be directed into the trench. 
     Preferably, as shown in  FIG. 1 , an aperture  20  is provided adjacent each corner of the grate section  16  to receive a fastener  18 . Various other types of locking and coupling devices, however, could also be used for securing the grate sections  16  to the frame  14 . Furthermore, although the frame sections  15  are shown here as separate and independent pieces, adjacent frame sections  15  can also be coupled together. For example, adjacent frame sections can include apertures for receiving threaded or other fasteners or coupling devices. 
     A preferred embodiment of the invention has been described in considerable detail. Many modifications and variations will be apparent to persons skilled in the art. Therefore, the invention should not be limited to the embodiment described but should be defined by the claims that follow.

Summary:
A frame for retaining a grate over a trench for directing storm water to subterranean basins includes a frame that is embedded in the concrete surrounding the trench. The frame includes a vertical support that is sized and dimensioned to abut the pavement wall of the trench, and a horizontal flange extending from the vertical support to support a grate. The horizontal flange and grate each include a plurality of apertures that are configured to be aligned to receive coupling devices for securing the grate to the frame. A chute is positioned beneath each aperture in the frame to direct debris from the aperture to the trench.