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CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/398,592 filed on Jun. 28, 2010, the contents of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to automatic cleaners for liquid-containing bodies and more particularly, although not necessarily exclusively, to tracked cleaners for pools and spas. 
       BACKGROUND OF THE INVENTION 
       [0003]    U.S. Pat. No. 4,449,265 to Hoy illustrates an example of a wheeled automatic swimming pool cleaner. Powering the wheels is an impeller comprising an impeller member and pairs of vanes. Evacuating the impeller causes water within a swimming pool to interact with the vanes, rotating the impeller member. The impeller is reversible, with the impeller member apparently moving laterally when the pool cleaner reaches an edge of a pool to effect the rotation reversal. 
         [0004]    U.S. Pat. No. 6,292,970 to Rief, et al., describes a turbine-driven automatic pool cleaner (“APC”). The cleaner includes a turbine housing defining a water-flow chamber in which a rotor is positioned. Also included are a series of vanes pivotally connected to the rotor. Water interacting with the vanes rotates the rotor in one direction (clockwise as illustrated in the Rief patent), with the vanes pivoting when encountering “debris of substantial size” to allow the debris to pass through the housing for collection. 
         [0005]    U.S. Patent Application Publication No. 2010/0119358 of Van Der Meijden, et al. discloses fluid-powered devices that may, for example, function as motors for APCs. Versions of the devices include paired paddles, with each paddle of a pair connected to the other paddle of a pair via a shaft. When a first paddle of a pair in a particular manner relative to flowing fluid, the other paddle of the pair is oriented approximately normal to the first paddle. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention provides innovative developments in the field of APCs. In particular, for APCs having tracks as part of their motive assemblies, the tracks may be formed so that their internal surfaces include teeth. The teeth may engage shift mechanisms for purposes of changing direction of movement of the cleaners. 
         [0007]    Additionally, a shift mechanism may include a cam designed to push a shifter in either of two directions so as to engage a different one of two (mitre) drive gears. Direction of travel of the APC depends on which drive gear is engaged. Beneficially, engaging one drive gear produces forward motion, whereas engaging the other drive gear produces rearward, or reverse, motion. 
         [0008]    Moreover, left and right sides of the APC differ for driving purposes. In some versions of the invention, different numbers of cams and teeth appear at one side of the cleaner as compared to the other side. Consequently, motion of the APC will not be constant, but instead will vary as a function of time. 
         [0009]    Lower portions of APCs of the present invention may include one or more bladed “fans” or “scrubbers.” Preferably, the blades are at least somewhat flexible; as such, they may accommodate larger items of debris being evacuated from the pool into the cleaner body. Positioning the scrubbers on either side of the debris inlet to the body also provides a wider cleaning path for the APC and produces vortexes actively inducing debris-laded water to flow toward the inlet. The scrubbers additionally produce downward force in operation, helping offset buoyancy forces and assisting the APC in remaining in contact with a to-be-cleaned surface. 
         [0010]    Cleaners of the present invention also may include easily-opening bodies. Certain versions incorporate a hood, or top, that may be moved to access internal body components; a presently-preferred version has a hinged top that may pivot to permit such access. Among other things, an easily-opening body facilitates removal of debris retained within the body. 
         [0011]    It thus is an optional, non-exclusive object of the present invention to provide improved APCs. 
         [0012]    It is another optional, non-exclusive object of the present invention to provide reconfigured tracks for track-driven APCs. 
         [0013]    It is also an optional, non-exclusive object of the present invention to provide tracks having teeth on their internal surfaces. 
         [0014]    It is a further optional, non-exclusive object of the present invention to provide shift mechanisms for non-robotic APCs. 
         [0015]    It is, moreover, an optional, non-exclusive object of the present invention to provide shift mechanisms in which cams cause shifters to engage differing drive gears. 
         [0016]    It is an additional optional, non-exclusive object of the present invention to provide bladed scrubbers producing downward force in opposition to upward buoyancy forces. 
         [0017]    It is yet another optional, non-exclusive object of the present invention to provide APCs with easily-opening bodies. 
         [0018]    Other objects, features, and advantages of the present invention will be apparent to those skilled in relevant fields with reference to the remaining text and the drawings of this application. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a perspective, generally side view of an exemplary scrubber of an APC of the present invention. 
           [0020]      FIG. 2  is a perspective, generally side view of an exemplary motive assembly of an APC of the present invention. 
           [0021]      FIG. 3  is a perspective, generally top view of portions of an exemplary body of an APC of the present invention. 
           [0022]      FIGS. 4-7  are perspective views of a shifting drive mechanism of an APC of the present invention. 
           [0023]      FIG. 8  is a perspective, generally bottom view of scrubbers (such as that of  FIG. 1 ) of an APC of the present invention. 
           [0024]      FIGS. 9-11  are various views of an alternate inlet of an APC of the present invention. 
           [0025]      FIG. 12  is a perspective, generally bottom view of an APC of the present invention showing scrubbers and the inlet of  FIGS. 9-11 . 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    Illustrated in  FIGS. 1 and 8  is exemplary scrubber  10  of the present invention. Scrubber  10  may include blades  14 , shaft  18  and, optionally, mitre or other gear  22 . In use, scrubber  10  desirably rotates about shaft  18  so as to move water or other liquid toward inlet  26  of body  30  of automatic pool cleaner  34 . Such rotation may be caused by interaction of gear  22  with a corresponding gear or other device typically located within body  30 . 
         [0027]    Blades  14  preferably are “semi-rigid” in nature. As used herein, “semi-rigid” means that blades  14  have sufficient flexibility to accommodate passage into inlet  26 , without blockage, of at least some larger types of debris often found in outdoor swimming pools. The term also means that blades  14  nevertheless have sufficient rigidity to move volumes of water toward inlet  26  as they rotate about shaft  18 . A presently-preferred material from which blades  14  may be made is molded thermoplastic polyurethane, although other materials may be used instead. 
         [0028]      FIGS. 1 and 8  depict the presence of eight blades  14  extending radially from shaft  18  and equally spaced about the circumference of the shaft  18 . Fewer or greater numbers of blades  14  may be employed as appropriate, however. Scrubber  10  additionally optionally may include wear surface  38  that may, at times, contact the surface to be cleaned. 
         [0029]    Shown in  FIG. 8  are two scrubbers  10  positioned opposite inlet  26 . In some versions of the invention, blades  14  of one scrubber  10  rotate clockwise about corresponding shaft  18 , while blades  14  of the other scrubber  10  rotate counterclockwise. Resulting is vortex action tending to induce debris-laden water toward inlet  26 . Such rotation also produces downforce biasing cleaner  34  toward a pool floor or other surface to be cleaned. In other versions, blades  14  of the one scrubber  10  rotate counterclockwise, with blades  14  of the other scrubber  10  rotating clockwise. In yet other versions of the invention, only one scrubber  10  may be utilized as part of cleaner  34 . 
         [0030]      FIG. 2  depicts aspects of motive assembly  46  of the present invention. Assembly  46  may include (closed-loop) track  50  having external and internal surfaces  54  and  58 , respectively. It also may include pulley or drive wheel  62  and undriven wheels  66  and  70 . An assembly  46  will be present at each of the left and right sides of cleaner  34 . 
         [0031]    External surface  54  of track  50  may contain treads  74  in any configuration suitable for facilitating movement of cleaner  34 . Of note, moreover, internal surface  58  of track  50  may include teeth  78 , which may be or comprise projections or protrusions of any suitable shape or size. As shown in  FIG. 2 , teeth  78  may be spaced longitudinally along internal surface  58  and generally laterally centrally located. In use, internal surface  58  bears against respective circumferential surfaces  82  and  86  of undriven wheels  66  and  70 . To accommodate the presence of teeth  78 , wheels  66  and  70  may have laterally centrally-located circumferential grooves  90  and  94  in which teeth  78  are freely received. 
         [0032]    By contrast, teeth  78  are designed to engage drive wheel  62 . Accordingly, clockwise rotation of drive wheel  62  (as shown in  FIG. 2 ) will move track  50  so that cleaner  34  moves to the left of the drawing of  FIG. 2 . Counterclockwise rotation of drive wheel  62  will move track  50  so that cleaner  34  moves to the left of the drawing of  FIG. 2 . Thus, both forward and rearward motion of cleaner  34  may be achieved. 
         [0033]    Illustrated in  FIG. 3  are portions of exemplary body  30  of the present invention. Body may comprise lower section  98  and upper section  102 . In the version of cleaner  34  depicted in  FIG. 3 , upper section  102  may contain outlet  106  through which water may exit the cleaner  34 . Upper section  102  additionally may include a swivel about outlet  106  for attachment of a hose. 
         [0034]    Upper section  102  further preferably is moveable relative to lower section  98  so as to expose interior  110  of body  30 . So exposing interior  110  facilitates both access to components of cleaner  34  within body  30  (including, if desired, a fluid-powered motor of the type disclosed in the Van Der Meijden application) and inspection and removal of any damaged centrally-located parts. It also may facilitate removal of debris lodged in interior  110 . As shown in  FIG. 3 , upper section  102  may be connected to lower section  98  using hinges  114 ; accordingly, it may pivot relative to lower section  98 . Other means of exposing interior  110  of body  30  may be employed instead, however, as appropriate or desired. 
         [0035]    Additional aspects of motive assembly  46  are illustrated in  FIGS. 4-7 . Opposite shaft  116  from drive wheel  62  is first gear  118 . Oriented generally perpendicular to shaft  116  is shaft  122  on which second gear  126  and third gear  130  are located. Second and third gears  126  and  130  are fixed to shaft  122  so that they rotate together as the shaft  122  rotates, with rotation of shaft  122  caused by a hydraulic motor or other propulsion source. 
         [0036]    First gear  118  is intended alternately to engage second gear  126  and third gear  130 . By engaging a rotating second gear  126 , for example, first gear  118  will be caused to rotate in a particular direction (e.g. counterclockwise), in turn rotating shaft  116  in the same direction. By contrast, if first gear  118  engages a rotating third gear  130 , first gear  118  and shaft  116  will be caused to rotate in the opposite direction (i.e. clockwise). Because it is fixed to shaft  116 , drive wheel  62  rotates as does the shaft  116 . Thus, merely by changing the engagement of first gear  118 , cleaner  34  may be caused to change its direction of travel from forward to reverse (or vice-versa). 
         [0037]    In  FIG. 4 , first gear  118  is shown as not engaging either second gear  126  or third gear  130 —in essence in a neutral position in which drive wheel  62  is not rotating. However, boss  134 , which surrounds shaft  116 , may pivot about shaft  138  so as to translate shaft  116  to its left or right, in turn causing first gear  118  to engage either second gear  126  or third gear  130 . If boss  134  pivots to the left of  FIG. 4 , first gear  118  engages second gear  126 . Pivoting of boss  134  to the right of  FIG. 4  causes first gear  118  to engage third gear  130 . 
         [0038]    A cam and gearing assembly  142  may be used to cause boss  134  to pivot either left or right about shaft  138 . Moreover, because two motive assemblies  46  preferably are used for a cleaner  34  (one on each side of body  30 , as mentioned earlier), their cam and gearing assemblies  142  may differ somewhat. Consequently, motion (direction, speed, or both) of one drive wheel  62  may differ at times from motion of the other drive wheel, causing cleaner  34  to move in non-linear manner. 
         [0039]      FIGS. 9-12  illustrate alternate inlet  26 ′ of the present invention. Inlet  26 ′ is either formed as part of lower section  98  of body  30  or attached to the lower section  98  (as shown in  FIG. 12 ) intermediate scrubbers  10 . Included as part of inlet  26 ′ may be both fluid opening  150  and scoop  154 , the latter configured to improve pick-up of debris. In particular, scoop  154  may comprise a rounded protrusion or bump  158  and an elongated, curved wall  162  (the continuation of which, denoted element  166 , may also be curved if desired). Bump  158  increases velocity of debris-laden water being pushed by scrubbers  10  toward opening  150 , while wall  162  effectively conveys (“scoops”) that water to the opening  150 . 
         [0040]    The foregoing is provided for purposes of illustrating, explaining, and describing embodiments of the present invention. Modifications and adaptations to these embodiments will be apparent to those skilled in the art and may be made without departing from the scope or spirit of the invention. As one of many examples of possible modifications, one or more cam and gearing assemblies  142  may be adjustable or programmable by a user of cleaner  34 . The contents of the Hoy and Rief patents and of the Van Der Meijden application are incorporated herein in their entireties by this reference.

Summary:
Automatic pool cleaners (APCs) and components thereof are detailed. The APCs may include tracks for movement, with the tracks having teethed internal surfaces. The APCs additionally may supply shift mechanisms for purposes of changing direction of their movement and incorporate bladed scrubbers and easily-opening bodies.