Abstract:
A filtering system with an improved backwashing capability includes influent and effluent means, and uses plastic beads as the filtering medium. The system further includes a plurality of backwash jets that eject water under pressure at angles such that the force of the water contacting the filter beads breaks apart the beads. Separating the filter beads allows the backwash operation to provide a far more thorough cleaning of the filter tank. This leads to improved performance of the filter and extended life of the filter media.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to filtering systems, and more particularly is a filter module with an improved backwashing method. 
     BACKGROUND OF THE INVENTION 
     In any scenario in which large amounts of water are utilized, a filtering system is necessary. Such scenarios include swimming and wading pools, fountains, fish tanks and ponds, and other aquaculture applications. The present invention was developed specifically for fish tanks and ponds, but is clearly applicable in any application requiring high volume filtering. 
     Most filtering systems utilize a filter tank with a filtering medium suspended in an interior of the tank. The filtering medium must be formed from a particulate material so that water can flow through the medium. Some media commonly used for filtering are diatomaceous earth, sand, gravel, and plastic pellets. The filter media remove contaminants from the water by trapping the contaminating material on the individual particles of the filter medium. After the filter system has operated for some time, there is clearly the danger of the filter being clogged by the trapped contaminants. Therefore a method of cleaning the filtering medium is required. 
     The method most commonly used for cleaning the filter medium in a filter tank is backwashing. Backwashing typically involves simply reversing the direction of water flow through the interior of the filter tank so that the trapped particulate matter is washed back out of the tank. One of the chief drawbacks of backwashing is that when the filter medium gets dirty, the particulate elements tend to clump together so that backwashing does not effectively remove the contaminants. This problem is recognized and addressed in the prior art. 
     One prior art method of attacking the aggregation of the filter media is by including a mechanical means of agitation in the tank. Two references that disclose such a scheme are the “Floating Media Biofilter” patents of Malone, U.S. Pat. No. 5,126,042, issued Jun. 30, 1992; and U.S. Pat. No. 5,445,740, issued Aug. 29, 1995. The devices disclosed in these references include an electric motor mounted on top of the filter tank. A vaned shaft passing through the interior of the tank rotates to stir the media. 
     Another method disclosed in the prior art entails an auger passing through the interior of the tank that continuously displaces the particles of the filter medium. This method is disclosed in “Fluid Filter Using Floating Media” by Junius et al., U.S. Pat. No. 5,573,663, issued Nov. 12, 1996. 
     Accordingly, it is an object of the present invention to provide a filtering system with an improved backwashing capability. 
     It is a further object of the present invention to provide a means of directing water flow in the backwash operation such that the water flow breaks up clumps of particulate media. 
     SUMMARY OF THE INVENTION 
     The present invention is a filtering system with an improved backwashing capability. The system has fairly typical influent and effluent means, and uses plastic beads as the filtering medium, as do many other systems. However, the system of the present invention further includes a plurality of backwash jets that eject water under pressure at angles such that the force of the water contacting the filter beads breaks apart the beads. Separating the filter beads allows the backwash operation to provide a far more thorough cleaning of the filter tank. This leads to improved performance of the filter and extended life of the filter media. 
     An advantage of the present invention is that the backwash water itself serves as a means to separate the individual filter media. 
     Another advantage of the present invention is that no external mechanical means is required for the media separation. 
     A still further advantage of the present invention is that the system is simple and inexpensive to manufacture. 
     These and other objects and advantages of the present invention will become apparent to those skilled in the art in view of the description of the best presently known mode of carrying out the invention as described herein and as illustrated in the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the filtering system of the present invention installed in a filter tank. 
     FIG. 2 is an exploded view of the filtering components. 
     FIG. 3 shows the system in a tank with filter media added, before the system is activated. 
     FIG. 4 illustrates the tank after the system has been activated. 
     FIG. 5 shows the condition of the tank after waste has begun to accumulate on the filter media. 
     FIG. 6 depicts the interior of the tank during the backwashing operation. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is a filter module  10  with an improved backwashing capability. With reference first to FIGS. 1 and 2, the filter module  10  comprises chiefly a first upright flow pipe  12  and a second upright flow pipe  14 . The flow pipes  12  and  14  form the main waterway of the filtering system, and are in communication with each other through a first joint  16 . An influent pipe assembly  18  is situated near a lower end of the module  10 . Two effluent pipes  20  are affixed to the first upright flow pipe  12  through second and third joints  16 . A backwash jet assembly  22  is situated near a top end of the first flow pipe  12 . A waste drain port is situated at a lower end of the first flow pipe  12 . A check valve  26  is installed midway in the first flow pipe  12 . 
     The influent pipe assembly  18  comprises a central hub  181  connected to the first flow pipe  12 . A plurality of lateral influent pipes  182  project outward from the central hub  181 . The influent pipes  182  comprise multiple influent ports  183  to allow water to flow from the flow pipe  12  into the filter tank  28 . The influent pipe assembly  18  serves to spread the water flow into the tank  28  from a single concentrated point, flow pipe  12 , to a widely dispersed area across the bottom of the filter tank  28 . 
     In the preferred embodiment, two effluent pipes  20  are T-shaped, and are connected to the first flow pipe  12  through joints  16 . The cross members  201  of the T-shaped effluent pipes  20  are situated near the top of the filter tank  28  for efficient collection of water. The effluent pipes  20  comprise a plurality of effluent ports  202  which take in water during the filtering operation. 
     The backwash jet assembly  22  projects outward from the first flow pipe  12 . The backwash jet assembly  22  comprises a plurality of lateral backwash pipes  221 , each of which includes multiple backwash jets  222 . The structure of the backwash jets  222  is critical to the operation of the filter module  10 . The backwash jets  222  are situated so that water is expelled downward at an angle. In the preferred embodiment, the angle relative to vertical of the center line of the water flow path leaving the backwash jets  222  is 45°. The backwash jets  222  are small enough and few enough in number so that the water is expelled at a high velocity. In the preferred embodiment, slots are simply machined into the pipes  221  to form the jets  222 . 
     Referring now to FIG. 3, before the filter system is activated, the filter tank  28  is partially filled with filter media  30 . In the preferred embodiment, the filter media  30  are plastic beads. Typically, approximately two-thirds of the filter tank  28  is filled with the filter media  30 . 
     FIG. 4 illustrates the situation in the tank  28  when the filtering system is first activated. Water flows into the tank  28  through the second flow pipe  14 . The water flows downward to the influent pipe assembly  18 . The direction of the water flow is ensured by the check valve  26 . Water flows through the central hub  181  into the lateral influent pipes  182  and out into the filter tank  28  through the influent ports  183 . As the water fills the tank  28 , the filter media  30  float toward the top of the tank  28 . 
     When the tank  28  is filled, water is drawn in through the effluent ports  202  in the effluent pipes  201 . The water is then pumped out of the tank  28  through the first flow pipe  12 , and returns to the pump reservoir. 
     As the filtering system operates, waste matter  32  naturally accumulates first on the lowermost filter media  30  as shown in FIG.  5 . Eventually, if the filter is not cleaned, the accumulated waste  32  will clog the filter so that it can not function properly. 
     For this reason, the filter system is equipped with an improved backwash capability. FIG. 6 shows the system during the backwashing operation. Water flow is reversed so that water flows into the tank through the first flow pipe  12  into the backwash jet assembly  22 . The water flows out through the backwash pipes  221 . As the water exits the backwash jets  222 , the flow area is significantly reduced. The reduction in flow area accelerates the water so that it is under pressure as it exits the jets  222 . The pressurized flow impinges on the accumulated filter media  30 , breaking the media  30  apart so that the water flow can effectively remove the waste material  32  from the filter media  30  as the water flows around the individual beads. 
     During the backwash operation, the water flow is now toward the bottom of the tank. The waste  32  removed from the filter media  30  accumulates at the bottom of the tank  28 . Because the water flow has been reversed, water is drawn through the waste port into the lower end of the first flow pipe  12 . Again, the direction of the water flow is ensured by the presence of the check valve  26 . The waste water is then directed upward through the second flow pipe  14 . The waste water is then pumped out of the system through a waste outlet as it exits the filter tank  28 , thereby completing the cleaning process. 
     The above disclosure is not intended as limiting. Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the restrictions of the appended claims.