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FIELD OF THE INVENTION  
       [0001]     This invention relates to apparatus for cleaning vessels such as swimming pools and more particularly to automatic swimming pool cleaners with either or both of innovative floats and water-temperature or -pressure indicators. It also relates to water-circulation systems incorporating such indicators.  
       BACKGROUND OF THE INVENTION  
       [0002]     U.S. Pat. No. 4,351,077 to Hofmann, incorporated herein in its entirety by this reference, discloses an exemplary automatic swimming pool cleaner. Included as part of the cleaner is a body (called a “head”) incorporating a buoyancy chamber. As described in the Hofmann patent, the buoyancy chamber preferably is provided with a hollow float. This chamber ensures that while the head will sink with the aid of any necessary weights onto the surface to be cleaned it will, nevertheless, be correctly orientated thereto. See Hofmann, col. 3, 11. 55-58 (numeral omitted). Such hollow float is not depicted in the Hofmann patent, however, nor is it otherwise detailed.  
         [0003]     U.S. Pat. No. 5,014,352 to Kallenbach, also incorporated herein in its entirety by reference, discusses automatic swimming pool cleaners likewise including a main body through which a fluid-flow passage extends. According to the Kallenbach patent, “normally used floats . . . have been removed and replaced” in favor of a hollow hemispherical part “[p]rojecting rearwardly from the upper part of the body.” See Kallenbach, col. 2, 11. 59-60; col. 3, 11. 19-22. In commercial embodiments of the cleaners of the Kallenbach patent, the hemispherical part is opaque and the float thus not visible.  
         [0004]     U.S. Pat. No. 5,882,512 to Denkewicz, Jr., et al., similarly incorporated herein in its entirety by reference, details additional automatic swimming pool cleaners which may filter water both mechanically and chemically. By contrast with the “suction-side” cleaners of the Hofmann and Kallenbach patent—which attach to the inlet side of a swimming pool water-circulating pump—various illustrated cleaners of the Denkewicz, Jr. patent connect to the outlet side of the pump. Such cleaners often are referred to as “pressure-side” cleaners and sometimes lack any sort of dedicated float.  
         [0005]     None of these patents explicitly identifies the shape of any buoyancy-enhancing float for an automatic swimming pool cleaner. None, further, describes a float visible to persons purchasing and using automatic swimming pool cleaners. Although the innovative cleaners of the Denkewicz, Jr. patent perform functions beyond mechanically filtering water, neither they nor other conventional swimming pool cleaners provide any indication of the temperature of the water or other fluid in which the cleaners operate. Having water-temperature indicating ability in a cleaner frequently may be useful, both in determining whether the water in the vessel is suitable for swimming and, potentially, in ascertaining whether the cleaner is likely to operate acceptably (or optimally).  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention provides automatic swimming pool cleaners or other mobile apparatus capable of indicating temperatures of the fluid in which they are placed for operation. Such indication may, but need not necessarily, occur through changes in color of one or more components of the cleaners. If the indication indeed is supplied through component color changes, at least one of the colors utilized preferably (but again not necessarily) is visible from outside the vessels in which the cleaners may be placed.  
         [0007]     Some embodiments of the present cleaners provide buoyancy-enhancing floats imbued with this water-temperature indicating ability. These floats preferably remain wholly or partly incorporated into the main bodies of the cleaners with which they are associated. Unlike floats of existing commercial cleaners, however, those of these embodiments are visible to users of the cleaners. Consequently, their colors may easily be viewed by prospective users of the pools without necessarily removing the cleaners from the pools.  
         [0008]     To permit this visibility, portions of the bodies of the cleaners may be formed of clear (non-opaque) materials. Some embodiments of the cleaners include a clear plastic window into a buoyancy chamber of the body through which the float may be seen. Alternatively, the body itself may be transparent or translucent, or a non-opaque chamber separate from the body may be employed.  
         [0009]     Various versions of cleaners consistent with the present invention may, as well, utilize floats shaped differently than existing commercial cleaner floats. These floats thus need not be spherical or cylindrical, as are at least some conventional floats. Instead, preferred floats may have oval or elliptical cross-section (or substantially so) and resemble eggs in three dimensions.  
         [0010]     Alternative embodiments of the invention position water-temperature indicating means elsewhere in water-circulation systems of swimming pools. Such systems typically include hoses, pumps, pipes, valves, and fittings through which pool water passes. Any of these or other portions of the systems could incorporate the indicating means, although preferably the means is located at least partially within the perimeters of the pools. Yet other versions include means for discerning information about pressures of water flowing to pressure-side cleaners.  
         [0011]     It thus is an optional, non-exclusive object of the present invention to provide mobile apparatus capable of indicating temperature of fluid in which they are deployed.  
         [0012]     It also is an optional, non-exclusive object of the present invention to provide swimming pool cleaners or other parts of water-circulation systems with water-temperature or -pressure indicating ability.  
         [0013]     It is another optional, non-exclusive object of the present invention to provide pool cleaners having one or more components adapted to change color as a function of the temperature of water in which they operate.  
         [0014]     It is a further optional, non-exclusive object of the present invention to provide pool cleaners containing floats with such color-changing characteristics.  
         [0015]     It is, moreover, an optional, non-exclusive object of the present invention to provide swimming pool cleaners having bodies in which the floats are placed, with the bodies adapted to permit the floats to be viewed externally.  
         [0016]     It is yet another optional, non-exclusive object of the present invention to provide pool cleaners with buoyancy-enhancing floats that are not spherical in shape.  
         [0017]     It is an additional optional, non-exclusive object of the present invention to provide pool cleaners whose floats are generally egg-shaped.  
         [0018]     Other objects, features, and advantages of the present invention will be apparent to those skilled in the appropriate field with reference to the remaining text and drawings of this application. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]      FIG. 1  depicts an exemplary float of the present invention adapted for use with an automatic swimming pool cleaner.  
         [0020]      FIG. 2  illustrates an exemplary automatic swimming pool cleaner in which the float of  FIG. 1  is employed.  
         [0021]      FIG. 3  is a block diagram of aspects of an exemplary water-circulation system containing water-temperature indicating means. 
     
    
     DETAILED DESCRIPTION  
       [0022]      FIG. 1  shows a version of float  10  of the present invention. As illustrated, float  10  has the general shape of an egg. As a consequence, float  10  may have an oval or elliptical cross-section. If appropriate or desired, float  10  additionally may include one or more recesses or projections to facilitate its placement or retention in automatic swimming pool cleaner  14  (see  FIG. 2 ).  
         [0023]     Preferred embodiments of float  10  are buoyant in water. Float  10  thus may be used to provide buoyancy to cleaner  14  depicted in  FIG. 2 . Together with weights conventionally used in such cleaners, float  10  may assist in balancing cleaner  14  as it moves within a pool or other vessel. Choosing an egg-shaped design for float  10  may, in some situations, enhance or optimize the righting moment of cleaner  14 . Those skilled in the art will, however, recognize that float  10  may be shaped other than generally as an egg and yet function acceptably in many versions of cleaner  14  (including those not resembling the version illustrated in  FIG. 2 ).  
         [0024]     Float  10  additionally may have one or more characteristics that change as a function of the temperature of the water within the pool within which cleaner  14  operates. In some embodiments of the invention (although not necessarily), float  10  is adapted to change color depending on ambient water temperature. As a non-limiting example of such adaptation, float  10  may be blue when the water temperature is less than approximately seventy degrees Fahrenheit (70° F.), bluish-green when the water temperature is approximately 70-80° F., and green when the temperature approximates 80° F. or more. Changes to other colors, or at other temperatures or ranges, may occur instead, however. Further, more than one such color change of float  10  may occur as a function of water temperature if appropriate or desired.  
         [0025]     A purpose of such color change may be to assist a pool owner, manager, or user in determining the suitability of the pool water for purposes of swimming, bathing, or other activities. Hence, having float  10  change color one or more times between, for example, 70-90° F. could be useful. Alternatively or additionally, float  10  could provide information concerning potential effectiveness of cleaner  14  in cleaning debris contained within a pool. Although the optimal temperature range for cleaning effectiveness may differ from cleaner to cleaner and is typically quite broad, some automatic pool cleaners may be able to clean better, or at lower water flow rates through the pump, when the ambient temperature of the water in which they operate is relatively warm. Hence, having float  10  change color below approximately 70° F., for example, may provide information as to its cleaning effectiveness at a particular time in a particular pool useful in determining whether then to operate cleaner  14 .  
         [0026]     Depicted in  FIG. 2  is a sample automatic pool cleaner  14  containing float  10 . Cleaner  14  defines body  18  and may be connected to or integrally formed with pad or disc  22 . Although not shown in  FIG. 2 , body  18  may include a water inlet circumscribed by disc  22 , as well as fluid-flow passage  26  terminating in outlet  30 . When cleaner  14  is operating, outlet  30  typically connects to a hose or pipe under control of a pump associated with a water-circulation system for the pool in which cleaner  14  resides.  
         [0027]     As illustrated in  FIG. 2 , body  18  incorporates buoyancy chamber  34  containing float  10 . Chamber  34  may be defined in part by non-opaque material  38 , preferably clear plastic, forming a window into the chamber  34 . Float  10  thus may be viewed through material  38  to ascertain its color without having to remove it from body  18 . Indeed, float  10  advantageously is visible through material  38  without removing cleaner  14  from the pool in which it may be placed.  
         [0028]     Alternatively, material  38  (and buoyancy chamber  34 ) may be omitted. In certain preferred embodiments lacking material  38 , float  10  is fitted into opening  40  of body  18  so that it is attached at and retained in the opening  40  (mid-way along the trailing edge of cleaner  14 ) but protrudes therefrom (as also shown in  FIG. 2 ). In these embodiments, float  10  is partially contained within body  18  yet extends outside the body  18  too. If desired, further, any or all of body  18  may be made transparent or translucent so that float  10  may be visible regardless of whether it is partly or wholly contained within the body  18 .  
         [0029]      FIG. 3  shows, in a block diagram, components of an exemplary water-circulation system  42 . System  42  may include swimming pool  46  wholly or partly filled with water, pump  50 , and piping  54  connecting the two. If present, automatic pool cleaner  14  may connect to piping  54  as well via hoses  56  or other means. Valves, fittings  57 , filter  58 , and other items or objects optionally may form part of system  42  too. An indicator of information concerning the temperature (or pressure) of pool water flowing through system  42  may be included as desired anywhere within the system  42 . As a non-limiting example of such an alternative placement, any of the hoses  56  used to connect cleaner  14  to piping  54  could be adapted to change color or some other characteristic as a function of water temperature or pressure. Those skilled in the art will recognize that, as depicted, system  42  is constructed for use with a pressure-side cleaner  14 , although it may be modified as appropriate for use with a suction-side of other cleaner  14  instead.  
         [0030]     The foregoing is provided for purposes of illustrating, explaining, and describing exemplary embodiments and certain benefits of the present invention. Modifications and adaptations to the illustrated and described embodiments will be apparent to those skilled in the relevant art and may be made without departing from the scope or spirit of the invention.

Summary:
Mobile apparatus, typically in the form of automatic swimming pool cleaners, capable of indicating temperatures (or pressures) of the pool water in which they are deployed are discussed. The indication may, but need not necessarily, occur through change in color of one of more components of the cleaners. Some versions may have floats adapted to provide this color change. These or other versions may include floats that are not spherical in shape as well. Alternatively, temperature (or pressure) indication may be provided by other aspects of a water-circulation system.