Abstract:
A drain grate in an opening to a drain system which retains trash and debris upstream from the opening while permitting slow flow of water, and which opens completely when confronted with high rates of flow.

Description:
FIELD OF THE INVENTION 
     A drain grate in an opening into a drain system which when closed retains trash and debris upstream from the opening while permitting slow flow of water, and which opens completely when confronted with high rates of water flow. 
     BACKGROUND OF THE INVENTION 
     Drainage systems that are situated in locations where trash and debris are carried along with the water are ubiquitous. In particular, unless prevented storm drains such as are found in gutters and drainage channels receive trash, cuttings, trimmings and other debris constantly throughout the year and are subject to clogging. During clement weather, the flow of water is usually rather slow, and is insufficient to flush the system, especially at catch basins and bends. Instead, despite regular sweeping upstream from the opening, considerable amounts of trash will enter the drain system, while still permitting the slow flow of water. 
     Serious trouble arises when later storms or other circumstances present water to these systems at high rates of flow while they are congested with the accumulated trash. Clogging of this system can result in upstream flooding, or the washing downstream of the accumulated material to do its mischief downstream. To avoid this situation, throughout the year maintenance crews are sent to clear out trash and debris that has entered the system through the openings. This is a considerable expense, and in the event that a storm strikes before the system is cleared, serious damage can occur despite those earlier efforts. 
     It is an object of this invention to provide a gate which will exclude trash and debris from the system while still permitting a slow flow of water, but which will open to allow full access for water (and entrained material) when the rate of flow is sufficiently high. When closed, the gate will permit the trash upstream from it to be removed by routine and collection sweeping, so as to remove trash that otherwise would later be driven into the system. 
     DETAILED DESCRIPTION OF THE INVENTION 
     This invention comprises a pivoted grate which is placed where it can occlude an opening from a drain into a collection system, or pivot to expose the opening to full flow. The grate is ported or otherwise channeled to allow water to pass through it when closed while retaining trash at low flow rates. In this condition, low flow rates such as are developed by watering of lawns, minor rains and the like are permitted, while holding back trash from the system where the trash can readily be swept away or otherwise removed without entering the drain system itself. 
     Under these benign conditions a linkage system which includes a variable-weight actuator allows the grate to close. When the weight increases as the consequence of a sufficiently higher rate of flow, the increased weight of the actuator will open the grate. 
     According to a feature of this invention, the actuator comprises a receptacle with a bleed port, which prevents the actuator from accumulating sufficient water (weight) to open the grate at slow rates of water flow, but which will accumulate sufficient water at higher rates to open the grate. 
     According to a preferred but optional feature of the invention, the actuator is mounted to a linkage which includes a toggle that prevents the grate from being opened by a force applied directly to the grate. 
     The above and other features of this invention will be fully understood from the following detailed description and the accompanying drawings, in which: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing a grate according to the invention installed in a curb opening, with the grate closed; 
     FIG. 2 is a view like FIG. 1, with the grate fully open to flow; 
     FIG. 3 is a side view partly in cross-section, showing a simple form of the invention installed as in FIG. 1 with the grate closed; 
     FIG. 4 is a view like FIG. 3, except that the grate is pivoted to open the curb opening; 
     FIG. 5 is a side view, partly in cross-section showing the presently-preferred embodiment of a grate system in its closed position; 
     FIG. 6 is a view like FIG. 5 showing the system with its grate open; 
     FIG. 7 is a side view partly in cross-section showing yet another system according to the invention; and 
     FIG. 8 is a perspective view of a preferred actuator for use in any of the embodiments. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a street-side installation of the invention. A typical gutter  10  and curb  11  are shown with an opening  12  to receive a grate  13 . An access cover  14  is placed over an access hole  15  in the top surface  16 . A collection basin  17  below hole  15  is provided to collect trash and debris which may somehow get through the opening. A pipe  18  leads to a drainage system (not shown). 
     Grate  13  is illustrated in FIG. 1 as a coarse screen. More frequently it may be a comb-like group of parallel rods, depending on the kind of location, and what is expected to be screened out. In any event clearances (sometimes called “gaps”) are provided to enable water to flow through the grate, while retaining trash, debris and the like. The grate is not intended to act as a dam to water. 
     As shown in FIG. 3, grate  13  is hinged at its top by hinge  20  so it can swing inwardly and upwardly as shown in FIG. 4. A frame  21  may conveniently be emplaced to hold the device. 
     An actuator  25  is suspended from end  26  of a lever  27 . The other end of lever  27  is hinged to the frame by hinge  28 . A pulley  29  is mounted to the frame to suspend and pass a flexible cable  30 . Cable  30  is attached to the free end of the grate, and to lever  27  (and thereby to the actuator). 
     The weight of the grate is sufficient to hold it closed against the torque exerted on it until there is sufficient weight of water in the actuator to overcome the weight of the grate itself. Additionally if preferred, a coil bias spring may be wound on the hinge  28 . Alternatively, lever  27  maybe spring-biased upwardly for the same purpose. 
     A preferred actuator  25  is shown in FIGS.7 and 8. It is an elongated trough having a pair of sidewalls  35 , 36  with a bleed port  37  at the bottom of the dihedral angle which they form. The width of the port determines the resistance to flow through it. End plates  38  close the structure. A dihedral screen  39  made of screen material excludes larger debris which might clog the bleed port. Much of what is caught on this screen will be washed away by a substantial flow of water. 
     As can be seen from FIG. 3, very slow water flow will simply drain down the wall of the chamber, or at least not reach the actuator. In FIG. 4, it is shown how flow  40  at a sufficient rate will reach the actuator, and if sufficient to fill the actuator (which is also draining to a sufficient level), its attained weight will draw the grate open and water will continue to flow into the actuator. The grate will close again when the flow of water into the actuator is slower than the drainage flow from it. 
     The simple arrangement of FIGS. 1-4 in uncomplicated, but does not resist being opened by direct force on the grate. The system of FIGS. 5-7 perform as in FIGS. 1-4, but include means to prevent the opening of the grate by forces exerted from the outside. 
     FIGS. 5-7 disclose a very useful feature. In the embodiment of FIGS. 1-4, a sufficient push on the grate will open it. It is useful to resist this event. For this purpose a toggle is provided which will hold the grate closed unless released by a force responsive to a sufficient weight on the actuator. 
     FIGS. 5 and 6 show an installation  50  in a curb  51 . The surrounding elements are identical and bear like numbers. Frame  52  hingedly supports grate  53 . An actuator  35  is suspended, but at the end of a different linkage. As before, a lever  54  has one end pivoted to the frame and its other to the actuator. Instead of a cable, a toggle linkage system  55  joins a midsection of lever  54  at pivot  55   a.    
     Toggle linkage system  55  includes a central link  56  hinged to the frame and a pair of toggle links  57 , 58 . A bias spring  60  biases central link  56  toward its locked position (FIG.  5 ). Link  58  is hinged to the grate. 
     Examination of FIG. 5 shows that the grate will be held closed against opening by a force exerted on it from the side by by the straight-line alignment of central link  56  and toggle link  58 . This toggle linkage will remain tight until the weight of the actuator overcomes the force of the bias spring and the weight of the grate itself, then it opens the toggle and the grate can open. 
     When the water retained in the actuator does reach the “critical” amount, the situation shown in FIG. 6 exists. Instead of a drip flow, or slow flow that does not reach the actuator, the flow  65  hits the actuator and water collects in it (less what drains from the drain port). 
     FIG. 7 illustrates the same system as in FIGS. 5 and 6, except that instead of a bias spring to drive the toggle system toward its locked condition, a weight  70  is attached to the central link, which exerts a constant force rather than a spring force to maintain the toggle lock. Otherwise the systems of FIGS. 5 and 7 are the same. 
     The operation of this system should be evident from the foregoing. The grate will be held closed to exclude trash and the like, but can pass the slow flow of water. When the rate of water flow becomes sufficient that it reaches out and fills the actuator the grate will be opened to pass whatever is presented to the opening where it is located. 
     This invention is not to be limited by the embodiments shown in the drawings and described in the description, which are given by way of example and not of limitation, but only in accordance with the scope of the appended claims.