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CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/759,618, filed Jan. 18, 2006. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to devices for cleaning tanks, pools, and other large water reservoirs, and particularly to a swimming pool cleaning device that provides a submergible structure for drawing water from the swimming pool while cleaning the swimming pool floor. 
         [0004]    2. Description of the Related Art 
         [0005]    A wide variety of systems have been utilized for cleaning swimming pools. Such systems typically include some sort of cleaning head, which is submerged within the swimming pool and rests on the pool bottom. An upper portion of the system is connected to an external pump, which provides suction to remove water from the pool for filtration and subsequent reentry into the swimming pool. The head of the device not only provides a suction head for the removal of water, but also cleans the surface upon which it rests. 
         [0006]    In order to clean the entire pool, rather than just a small portion, various drive systems have been added to the cleaning heads of such swimming pool cleaners. Basic drive systems include a towing line or other simple devices for the user to manually pull the cleaning system across the floor of the pool. Various automated systems have also been utilized, including basic propeller driving systems and systems that divert the flow of the water under suction pressure to an outlet, thus creating a driving jet stream. Such systems, however, are inefficient and their multiplicities of moving parts cause them to be vulnerable to misalignments and other mechanical failures. Further, such systems tend to create vortices, turbulence and other negative fluid flow effects, which will obstruct the movement of the cleaning head and can cause the cleaning head to become dislodged from the floor of the swimming pool. Thus, a swimming pool cleaning device solving the aforementioned problems is desired. 
       SUMMARY OF THE INVENTION 
       [0007]    The swimming pool cleaning device is a submergible structure for drawing water from a large receptacle, such as a swimming pool, to be cleaned, and further for cleaning a submerged surface of the receptacle, such as the swimming pool floor. The swimming pool cleaning device includes a pair of suction tubes, which communicate with a pressurized source, such as a pump, to suck water from the swimming pool for cleaning and later return to the swimming pool. Water is drawn through a lower head portion, through one of the two suction tubes, and then through a regulating ball valve before being delivered to the separate pump and filter systems. 
         [0008]    A flapper valve is mounted to the lower ends of the suction tubes and controls entry of water into the suction tubes, alternating water flow between one tube and the other. The flapper valve alternates between sealing one suction and the other through application of Bernoulli&#39;s principle. The oscillatory flow between the two suction tubes imparts horizontal momentum to the swimming pool cleaning device, allowing the swimming pool cleaning device to travel along a surface of the pool without further user-provided motive force. Further, a base plate is mounted within the head portion below the flapper valve and regulates water by providing a pair of passageways, each in alignment with one of the two suction tubes. Drawing water through the openings in the base plate reduces the formation of vortices and other turbulence within the head portion. 
         [0009]    The swimming pool cleaning device may include an outer housing for protecting the components within the head portion and the suction tubes. The housing may include elements, such as rings, allowing the user to tie or tether the swimming pool cleaning device, so that the device can only move within a restricted area. Further, a buoyant member may be affixed to the housing, thus providing an upward buoyant force and decreasing the friction of the device against the swimming pool floor. 
         [0010]    These and other features of the present invention will become readily apparent upon further review of the following specification and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a perspective view of a swimming pool cleaning device according to the present invention. 
           [0012]      FIG. 2  is a side view in section of the swimming pool cleaning device according to the present invention. 
           [0013]      FIG. 3  is a partial side view in section of the swimming pool cleaning device shown in  FIG. 2 , showing an enlarged view of the head portion. 
           [0014]      FIG. 4  is a top view of a base plate of the swimming pool cleaning device according to the present invention. 
       
    
    
       [0015]    Similar reference characters denote corresponding features consistently throughout the attached drawings. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0016]    The swimming pool cleaning device  10 , shown in  FIG. 1 , cleans and purifies water contained within a large, manmade receptacle, such as a swimming pool, and further cleans the submerged surfaces of the receptacle. The upper end of the swimming pool cleaning device  10  includes a connector  240  for connection with a pressurized tube or hose. The tube or hose is connected to a conventional pump and purification system, as is often associated with the cleaning of swimming pools. The water is drawn out of the swimming pool by the pump, delivered to the purification system, and then returned to the swimming pool, once cleaned. Preferably, connector  240  is threaded, for connection to a conventional threaded hose, although any suitable connector may be utilized, dependent upon the nature of the tube or hose. 
         [0017]    Water from the swimming pool is drawn through the lower portion of device  10 , as indicated by directional arrows  270 . As will be described in greater detail below, the water is drawn upwards through device  10 , and exits at the upper end thereof, under the pressure created by the attached pump, as indicated by directional arrows  300 . The suction of water through the lower end of device  10  causes the lower surface of head portion  20  to adhere to a surface of the receptacle, such as the floor of the swimming pool. Further, as will be described in greater detail below, the suction of water through device  10  causes device  10  to move across the surface of the swimming pool, thus allowing for automatic cleaning of the entire swimming pool without a separate user-applied pushing or pulling force. 
         [0018]    As shown in  FIG. 1 , once water has been drawn through head portion  20 , it is delivered to the upper end of device  10  through a pair of suction tubes  110 ,  120 . In a manner that will be described in greater detail below, water flow alternates between suction tube  110  and suction tube  120 ; it is this oscillation of water flow path that creates a driving force for device  10  to move within the swimming pool. Head  20  and suction tubes  110 ,  120  are preferably formed from a durable, waterproof material, such as plastic, that will not corrode when submerged in water, and further, that will not cause damage to the receptacle walls or floor. Alternatively, in order to protect suction tubes  110  and  120 , an outer casing, also formed from plastic or the like, may be provided, as illustrated in the embodiment of  FIG. 2 . 
         [0019]    Housing  330 , shown in  FIG. 2 , covers and protects suction tubes  110  and  120 , and provides further protection for the internal elements of head portion  20 , which will be described in greater detail below. A buoyant region  310  is formed in housing  330 , which is a hollow region containing air, foam or other buoyant materials (with the buoyancy preferably being taken with respect to water, particularly in use with swimming pools or the like). In operation, the suction of water through device  10  causes the lower wall  230  (best shown in  FIG. 3 ) of device  10  to adhere to a surface of the swimming pool, such as the pool&#39;s floor. However, device  10  also experiences a lateral force, which moves the swimming pool cleaning device  10  around the swimming pool, thus the buoyant region  310  is provided to decrease the force of friction against lower wall  230 , caused by the swimming pool floor, allowing the device  10  to move relatively freely. 
         [0020]    Further, at least one connection element  340  may be formed on the lower end of housing  330 . In  FIG. 2 , connection elements  340  are shown as rings for receiving a rope, tether or the like, thus allowing the user to tether device  10  to a particular region of the swimming pool. Although shown as rings, connector elements  340  may be any suitable connectors for attachment of a rope, tether or the like. Additionally, a stabilizing fin  250  may be formed on housing  330  and project outwardly therefrom. Stabilizing fin  250  provides for additional stability for device  10  in the event device  10  should move into a region of water containing vortices, turbulence, relatively high-velocity fluid flow or other destabilizing currents. 
         [0021]    As shown in  FIG. 2 , once water is sucked into head portion  20  of device  10 , as indicated by directional arrows  270 , a flapper valve  30  allows water to flow either through suction tube  120  (shown by directional arrow  290 ) or through suction tube  110  (shown by directional arrow  280 ). The upper ends of suction tubes  110  and  120  join within a manifold or juncture chamber  111 , where flow through connector portion  240  may be first regulated with a ball valve  320 . 
         [0022]    As best shown in  FIG. 3 , flapper valve  30  is pivotally connected, at an upper end thereof, to support member  151 . Flapper valve  30  is pivotally mounted through use of a pivotal connector  150 , which may be a pivot pin or the like. Water is drawn through opening  220  formed in lower wall  230  of the head portion  20 . The water enters chamber  85 , where it is then drawn through openings  40 ,  50  (illustrated by directional arrows  60  and  70 , respectively), formed through base plate  80 . Openings  40 ,  50  are aligned with the lower ends of tubes  110 ,  120 , respectively, as shown. The flow of water through openings  40 ,  50 , rather than directly from chamber  85  into chambers  90  and  100 , acts to smooth and regulate the water flow, decreasing the possibilities of turbulence, vortices and other negative effects associated with fluid flow, which could disrupt operation of system  10 . 
         [0023]    As best shown in  FIG. 4 , base plate  80  has a substantially rectangular contour and includes a main plate portion  180 , which has a substantially planar configuration. Openings  40  and  50  are formed through main plate portion  180  and, although openings  40  and  50  are shown as having a substantially oval contour, it should be understood that this is for exemplary purposes only, and openings  40  and  50  may have any suitable contour, for example, a rectangular contour. 
         [0024]    It should be noted that in conventional pool cleaning systems, base plates similar to base plate  80  are typically provided with only a single opening formed therethrough. A single opening system provides a rather limited flow of water and, due to the Venturi Effect and other causes of turbulence and vortices of dynamic fluid flow, tends to cause interruption in the fluid dynamic effect that causes the system to move. By contrast, the dual openings  40 ,  50  formed in the base plate  80 , however, provide for a continuous fluid flow, with a greater volume of water passing therethrough at a greater rate, thus maintaining system  10  in continuous motion. This continuous motion provides for optimal cleaning of the swimming pool surface. 
         [0025]    The laterally opposed edges of base plate  80  include a raised rim portion  190 . Further, an opening  160  is formed centrally through one edge of base plate  80 , and a pair of engaging tabs  200  are formed on the opposite edge of base plate  80  and project outwardly therefrom. Returning to  FIG. 3 , base plate  80  is positioned at an angle with respect to lower wall  230 , and the first end of base plate  80  is secured by a fastener  170 , which may be a rod or the like, which is received through opening  160 . Further, a pair of recesses  210  are formed in lower wall  230  for receiving tabs  200 , thus securing base plate  80  within head portion  20  and dividing the interior of head portion  20  into lower chamber  85  and upper chambers  90 ,  100 . 
         [0026]    In the configuration shown in  FIG. 3 , flapper valve  30  is shown as contacting wall  130 , thus causing fluid to flow into chamber  100  (and subsequently through suction tube  120 ), and preventing fluid flow into chamber  90 . Due to Bernoulli&#39;s principle, the flowing water passing into chamber  100  and suction tube  120  is under lower pressure than the water at rest in chamber  90 . Thus, flapper valve  30  will experience a motive force, rotating flapper valve  30  so that it contacts wall  140 , thus sealing chamber  100  and tube  120 , and allowing water to flow under pressure into chamber  90  and tube  110 . 
         [0027]    The water in sealed chamber  100 , however, still retains an upward momentum and the horizontal component of this momentum is transferred into device  10 , causing slight horizontal movement in the direction shown by directional arrow  260 , in  FIG. 2 . It should be noted that this driving force in the horizontal direction is relatively weak, but not negligible, and will cause device  10  to move across the floor of the swimming pool in the direction indicated. Following a similar process, the pressure of the moving water in chamber  90  and suction tube  110  is now at a lower pressure than that in chamber  100 , thus causing flapper valve  30  to rotate in the opposite direction and, once again, make contact with wall  130 , sealing of chamber  90  and allowing water to flow into chamber  100 . The water in chamber  90  and tube  110  also retains upward momentum with a horizontal momentum component, which is transferred to device  10  in the manner described above, creating horizontal movement in the direction of arrow  260 . 
         [0028]    The oscillatory nature of the water flow between suction tubes  110  and  120  generates a small but non-negligible horizontal movement of device  10 , thus allowing device  10  to automatically travel through the swimming pool and cover the entire surface to be cleaned, such as the swimming pool floor, without additional user-applied driving force. 
         [0029]    It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.

Summary:
The swimming pool cleaning device is a submergible structure for drawing water from a tank, such as a swimming pool, to be cleaned, and further for cleaning a submerged surface of the tank, such as the swimming pool floor. The swimming pool cleaning device includes a pair of suction tubes, which communicate with a pressurized source, such as a pump, to suck water from the swimming pool for cleaning and later return to the swimming pool. A flapper valve controls entry of water into the suction tubes, alternating water flow between one tube and the other. The oscillatory flow between the two suction tubes imparts horizontal momentum to the swimming pool cleaning device, allowing the swimming pool cleaning device to travel along a surface of the pool without further user-provided motive force.