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CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 62/275,851, filed Jan. 9, 2016 and herein incorporated by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to a floating swimming pool cover useful in reducing evaporation and retaining heat and, more particularly, to a floating cover formed of corrugated polyethylene, with the corrugations formed along the surface that contacts the water, creating a vapor barrier. 
       BACKGROUND OF THE INVENTION 
       [0003]    Swimming pools lose a significant amount of heat and water through surface evaporation. To maintain a comfortable temperature in the pool, as well as to keep a relatively consistent water level, it is necessary to frequently add both water and heat to the pool. This can not only add considerable expense, but may also shorten the season during which the pool is usable. It is known to use a removable cover that functions as a vapor barrier to reduce evaporation. Similar vapor barriers are also beneficial for use with indoor pools, where evaporated water not only requires adding heat to the pool, but also produces humidity issues in the pool room. 
         [0004]    One exemplary type of vapor barrier is formed of a type of flexible bubble wrap, similar in form to packing material. While useful for relatively small pools, the effort required to cover larger, competition-sized pools is problematic. That is, the covers are challenging to put on and take off as they often do not hold their shape or wind up “true”. And even if it is possible to evenly roll up a cover of such an extensive size, it is difficult to find a place to store the cover where it isn&#39;t an eyesore (and where it is protected when not in use). 
         [0005]    Other types of pool covering have been developed. In one case, a plurality of individual, floating plastic pads is used, where a multiple number of pads are positioned on the surface (obviously, larger pools needing a larger number of these pads). Since they need to be individually placed and removed, their use is time-consuming. Again, these pads present storage problems. 
         [0006]    Some systems utilize a cover that is attached to a pair of tracks that extend along the length of the pool, where the cover is moved via a cable-driven system to slide along the tracks and cover the pool. While effective, this type of configuration is obviously expensive and cannot be used on large pools. 
         [0007]    Thus, a need remains for a relatively simple and efficient pool cover that may be quickly and easily placed on a pool and function to reduce evaporation and retain heat, using a system of covering/uncovering that avoids the various problems of the prior art. 
       SUMMARY OF THE INVENTION 
       [0008]    The needs remaining in the prior art are addressed by the present invention, which relates to a floating swimming pool cover useful in reducing evaporation and retaining heat and, more particularly, to a floating cover formed of corrugated polyethylene, with the corrugations formed along the surface that contacts the water, creating a vapor barrier. 
         [0009]    In accordance with an exemplary embodiment of the present invention, the corrugated polyethylene pool cover (which is flexible) is wound onto a storage shaft when not in use to cover a pool. A drive shaft is disposed in a spaced-apart relationship with the storage shaft. When it is desired to deploy the cover over the surface of a pool, the cover passes over the drive shaft and the corrugations on the polyethylene sheet engage with gear teeth on the drive shaft. Thus, as the drive shaft is rotated, the cover is pulled off the storage shaft and pushed out and away from the shafts and onto the pool. Conversely, when it is desired to remove the cover from the pool, the storage shaft is rotated in a manner that functions as a take-up reel and allows the cover to be pulled off of the pool and wound up on the storage shaft. 
         [0010]    In a preferred embodiment of the present invention, an external drive motor is used to control the operation of both the drive shaft and the storage shaft. However, it is to be understood that conventional manual operations may be used to crank the appropriate shaft so as to either “pay out” or “take up” the cover. 
         [0011]    In an exemplary embodiment of the present invention, the drive shaft may be covered with a piece of polyethylene having the same corrugations as the pool cover, these corrugations functioning as the gear teeth. A conventional drive shaft with machined teeth (or any other suitable type of teeth) may also be used. 
         [0012]    One particular embodiment of the present invention includes an outer housing, with both the storage shaft and the drive shaft formed as components within the housing. A hinged ramp may be included in a specific configuration of the outer housing, where the ramp bridges the distance between the housing and the edge of a given pool and serves as a platform to support the movement of the cover between the drive shaft and the pool, ensuring that the edge of the cover is launched onto the water&#39;s surface. 
         [0013]    An additional pressure shaft may be included in any embodiment of the present invention, where the pressure shaft is disposed over the drive shaft and positioned such that the cover is threaded between the pressure shaft and the drive shaft. In this manner, the cover is more likely to remain in contact with the drive shaft, where the rotation of the drive shaft urges the cover forward and onto the surface of the pool. 
         [0014]    Configurations of the present invention that utilized motorized control of the rotation of the storage shaft and drive shaft may include the use of limit switches that sense when the entire cover has been played out over the surface (and thus turning “off” the drive shaft) and sense when the entire cover has been removed from the pool (and thus turning “off” the storage shaft). A remote control feature may be added to this motorized power source as well. 
         [0015]    One particular embodiment of the present invention may be defined as a pool cover apparatus comprising a vapor barrier sheet formed of a flexible material, the vapor barrier flexible material for covering a defined surface of a and including a corrugated lower surface for contacting the water when in place on the pool, a storage shaft for supporting the vapor barrier sheet when not in use (the vapor barrier sheet wound upon the storage shaft in this condition) and a drive shaft disposed in relation to the storage shaft such that as the vapor barrier sheet is unwound from the storage shaft, it passes over the drive shaft and onto the pool, the drive shaft including gear teeth that mate with the corrugated lower surface of the vapor barrier sheet such that as the drive shaft is rotated, the corrugated lower surface of the vapor barrier sheet engage with the gear teeth and impart forward movement of the sheet. 
         [0016]    Other and further aspects and embodiments of the present invention will become apparent during the course of the following discussion and by reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    Referring now to the drawings where like numerals represent like parts in several views, 
           [0018]      FIG. 1  illustrates the pool cover apparatus of the present invention as located in position along an edge of a pool, where in this view a portion of the vapor barrier sheet has begun to unwind from the apparatus and positioned over the pool surface; 
           [0019]      FIG. 2  is an isometric view of an exemplary corrugated polyethylene material that may be used to form the vapor barrier sheet; 
           [0020]      FIG. 3  is a cut away side view of the inventive apparatus, showing the vapor barrier sheet in place on the storage shaft, and threaded between the drive shaft and the pressure shaft as it exits the housing; and 
           [0021]      FIG. 4  is an alternative cut-away front view of the inventive apparatus, with the vapor barrier sheet removed to better illustrate the positioning of the various shafts, as well as an external power source that may be used to impart rotational motion to the drive shaft and storage shaft. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]      FIG. 1  illustrates an exemplary floating pool cover apparatus  10  formed in accordance with the present invention. In the view of  FIG. 1 , the cover is partially deployed (that is, in the process of being played out) onto a pool P. More particularly, the cover is being deployed so as to float on water surface S within pool P. Apparatus  10  is shown as being positioned at an edge of pool P. It is contemplated that a particularly advantageous embodiment of the present invention is to utilize an apparatus  10  that is sized to cover an individual lane of a pool (for example, an indoor pool of a specific length for competitive swimming). When used in this context, a multiple number of the same apparatus may be lined up along the edge of the pool, with each cover apparatus  10  used to cover an individual lane. 
         [0023]    As will be discussed in detail below, cover apparatus  10  includes a vapor barrier sheet  12  that is formed of a flexible material (preferably, polyethylene) having a corrugated surface.  FIG. 2  is an isometric view of a section of vapor barrier sheet  12 . In this case, sheet  12  is formed of multiple layers of polyethylene material fused together in a known fashion. In the particular embodiment of  FIG. 2 , sheet  12  is shown as include a relatively smooth top layer  16 , with a corrugated polyethylene layer  14  attached across a surface of layer  16 . 
         [0024]    As mentioned above, corrugated polyethylene layer  14  includes a series of corrugations  18  disposed in parallel across the width W of sheet  12 . In accordance with the present invention, the open end faces  18 -O of the corrugations are filled, joined together, or in some manner pinched close so as to prevent water from entering these openings and weighting down vapor barrier sheet  12 . The air pockets formed by closing end faces  18 -O provides buoyancy and stiffness to the cover, while allowing the sheet to retain sufficient flexibility to be rolled up when not in use. While the specific embodiment of  FIG. 2  illustrates a “multilayer” configuration, it is to be understood that a single sheet of polyethylene formed to include corrugations along one surface may also be used in the pool cover system of the present invention. 
         [0025]      FIG. 3  is a cut-away side view of cover apparatus  10 , which best illustrates the inner workings of apparatus  10  as used to control the deployment (i.e., “pay out”) of sheet  12  onto pool surface S, as well as control the removal (retraction) of sheet  12  from pool surface S. For the purposes of the following discussion, it is useful to also refer back to  FIG. 1  during the description of the individual components of apparatus  10  as shown in  FIG. 3 . 
         [0026]    Vapor barrier sheet  12  is shown in  FIG. 3  as being wound on a storage shaft  20 . A drive shaft  22  is disposed in relation to storage shaft  20  so that sheet  12  will contact drive shaft  22  as it is unrolled (that is, as storage shaft  20  rotates). In accordance with the teachings of the present invention, drive shaft  22  is formed to include gear teeth  24  that mate with corrugations  18  of vapor barrier sheet  12 . Therefore, as drive shaft  22  is powered (either using a motor or manually) to rotate, the motion of gear teeth  24  will encourage the forward movement of vapor barrier sheet  12  off of storage shaft  20  and onto water surface S of pool P. Gear teeth  24  can be formed by directly machining (or otherwise manufacturing) the proper depth and spacing of indentations around the surface of drive shaft  22 . Alternatively, a section of the material forming vapor barrier sheet  12  may be disposed to cover the outer surface of drive shaft  22  and positioned with corrugations  18  exposed; in this manner, the exposed corrugations will easily mesh with the corrugations on the actual sheet and enable its movement outward and onto the pool surface. 
         [0027]    In accordance with the present invention, therefore, the rotation of drive shaft  22  functions to deploy vapor barrier sheet  12 , extending sheet  12  across water surface S. Vapor barrier sheet  12  is wound on storage shaft  20  such that as it begins to deploy, lower corrugated surface  14  of sheet  12  contacts the water, with corrugations  18  floating on the surface. The rotation of drive shaft  22  can be accomplished by using a motorized system as the power source. Alternatively, a manual system utilizing a crank handle attached to drive shaft  22  may be used to “power” the shaft (and/or may serve as a back-up when other power sources are not available). 
         [0028]    Continuing with the description of  FIG. 3 , when it is desired to remove vapor barrier sheet  12  from water surface S, storage shaft  20  is activated to rotate, thus winding up sheet  12  in a controlled manner. Advantageously, corrugations  18  assist in retaining sheet  12  aligned as it engages gear teeth  24  on drive shaft  22 . Again, a motorized unit can be used as the power source to activate storage shaft  20 , or hand crank mechanism may be attached to shaft  20  and used to create the rotation. 
         [0029]    The specific embodiment of the present invention as shown in  FIG. 3  also includes a pressure shaft  26  disposed to maintain vapor barrier sheet  12  in contact with drive shaft  22 . In particular, pressure shaft  26  includes a lever arm  28  attached to sidewalls  44  by a pivot member  30 . A spring  32  is attached near the opposing end of lever arm  28 , providing the force required to keep pressure shaft  26  pushing vapor barrier sheet  12  onto drive shaft  22 . Thus, as vapor barrier sheet  12  is threaded between pressure shaft  26  and drive shaft  22 , the tension created by spring  32  forces sheet  12  down onto drive shaft  22 , allowing for corrugations  18  of sheet  12  to remain engaged with gear teeth  24  of drive shaft  22 . 
         [0030]    This specific embodiment as shown in  FIG. 3  further comprises a ramp  34  which extends downward from apparatus  10  and into pool P, facilitating the movement of vapor barrier sheet  12  from apparatus  10  and into the pool. Advantageously, the presence of ramp  34  serves to remove additional water from corrugations  18  when vapor barrier sheet  12  is being removed and wound onto storage shaft  20 . In a preferable configuration, ramp  34  is hinged onto housing  40 , and can be folded up against housing  40  when not in use. 
         [0031]    As mentioned above, a significant aspect of the present invention is that the specific components of cover apparatus  10  are stored within a housing that keeps vapor barrier sheet  12  protected when not in use, and can easily be stowed away. Referring to  FIGS. 1 and 4 , cover apparatus  10  is shown as including a housing  40  useful for configuration the various shafts in their proper positions, while also protecting sheet  12  when not in use.  FIG. 4  is a cut-away side view of housing  40 , without sheet  12  in place so that the positioning of storage shaft  20 , drive shaft  22  and pressure shaft  26  is clearly shown. 
         [0032]    Referring to  FIG. 4 , storage shaft  20  is shown as supported at opposite end terminations by a pair of bolts  42 . In accordance with the present invention, storage shaft  20  passes through sidewalls  44  of housing  40 , with bolts  42  located exterior to housing  40 . Similarly, drive shaft  22  is shown as passing through sidewalls  44  of housing  40 , with a pair of bolts  46  attached to opposing end terminations of drive shaft  22 . Thus, in order to impart rotational movement to drive shaft  22  and deploy sheet  12  (not shown in  FIG. 4 ) to cover the pool, a power source  50  (i.e., a motorized unit) can be attached to either one of bolts  46 . The activation of power source  50  is used to create a rotational motion which translated through bolts  46  and attached drive shaft  22 , causing drive shaft  22  to rotate. Power source  50  may similarly be coupled to bolts  42  of storage shaft  20  and used to initiate rotation of shaft  20  when it is desired to remove sheet  12  from the surface of the pool. 
         [0033]    Power source  50  may also include limit switches. In particular, a first limit switch  52  may be used to sense when the entire sheet  12  has been unwound from storage shaft  20 . At this occurrence, first limit switch  52  will stop the rotation of drive shaft  22  by turning off the power source. Similarly, a second limit switch  54  may be used to sense when the entire sheet  12  has been re-wound onto storage shaft  20 . At this occurrence, second limit switch  54  will stop the rotation of storage shaft  20  by turning off the power source. In both cases, these limit switches provide the ability to control the rotational power delivered to the shafts and improve the performance of apparatus  10 . 
         [0034]    It is to be understood that the power source may operate via remote control, such as via RF signals received by an antenna  56 . In this embodiment, an individual located within range of power source  50  may control the operation of apparatus  10  without needing to stand right next to the pool. 
         [0035]    As mentioned above, a manual operation system may be used instead of power source  50  to control the operation of cover apparatus  10 . That is, a crank arm may be attached to the proper bolts (i.e., either bolts  42  or bolts  46 ) and used to manually rotate the appropriate shaft to deploy or retract vapor barrier sheet  12 . 
         [0036]    Pressure shaft  26  is shown in  FIG. 4  as being completely encased within housing  40 , since there is no need to provide external rotational force to this shaft ( FIG. 3  also shows the positioning of pressure shaft  26 ). Housing  40  is shown in  FIG. 4  as resting on a set of casters  48 , which are useful in allowing for apparatus  10  to be positioned near the pool when being used, and simply rolled away when not in use. 
         [0037]    It is to be understood that the present invention is not limited to the above-described embodiments, but encompasses any and all variations that are contemplated as falling within the scope of the following claims.

Summary:
A pool cover apparatus includes a sheet of corrugated polyethylene as a vapor barrier, where the sheet is wound onto a storage shaft when not in use. A drive shaft is disposed in a spaced-apart relationship with the storage shaft. When it is desired to deploy the sheet to cover the surface of a pool, the sheet passes over the drive shaft and the corrugations on the polyethylene sheet engage with the teeth on the drive shaft. Thus, as the drive shaft rotates, it causes the vapor barrier sheet to continue to move out and away from the shafts and cover the pool. Conversely, when it is desired to remove the sheet from the pool, the storage shaft is engaged, rotating in a manner that functions as a take-up reel and winds the vapor barrier sheet up on the shaft for storage.