Water temperature regulating pool cover

Abstract

A pool cover for temperature regulation of pool water having an upper sheet of flexible material and a lower sheet of flexible material. The sheets are joined together at their side edges and along a plurality of longitudinally seams to form a panel having a plurality of longitudinal seams to provide a plurality of flow channels. A pump attached to an input tube draws in water from the pool, and via an input manifold forces the pumped water through the flow channels in the panel, and out the ends of the flow channels back into the pool. Pool water pumped through the flow channels picks up heat from incident solar radiation and the ambient air temperature, or gives off heat to the ambient environment, depending on the temperature of the air, the amount of incident radiation, and the temperature control settings provided by the user.

Description

FIELD OF THE INVENTION

The present invention is related to temperature control systems, temperature regulation systems, heat collectors, and heat insulators. The present invention is also related to swimming pool equipment, and more particularly to swimming pool covers and particularly swimming pool covers for control and/or regulation of pool water temperature.

BACKGROUND OF THE INVENTION

Swimming is a much enjoyed recreation and a useful exercise. However, there is a rather narrow range of water temperatures that are considered desirable, and water temperatures which are too warm, especially in a warm climate, or too cold, especially in a cold climate, are problematic. Therefore, there is much call for an economical, easy-to-use pool cover which will effectively heat pool water using solar energy, thereby reducing heating costs and extending the range of seasons during which a pool can be used. This is particularly an issue in the more Northern and Southern latitudes where temperatures drop considerably in the fall and spring relative to the summer. Furthermore, in hotter regions, radiant energy from the sun may warm a pool to an undesirably high temperature, so there is also call for a system for cooling pool water. Water has a relatively large heat capacity and pools contain large quantities of water, so it is particularly important that the means for temperature regulation for pools be efficient and economical. This may become even more of an issue as climate changes result in unusual weather patterns.

Typical pool covers float on the water's surface when laid out, and are typically retracted by spooling onto an axle. Some pool covers are designed to be laid out and retracted (i.e., “positioned”) manually, while others are positioned using an electric motor attached to cables that run along the sides of the pool. Traditional swimming pool covers do provide some heat insulation. Swimming pool covers are also useful for prevent evaporation of pool water and pool chemicals, and are used for safety purposes to prevent people, particularly unattended children, from falling into a pool.

Consider a typical spring or fall day, for instance, in Austin, Tex., where the solar radiation at ground level is about 650 W/m², and a pool owner is hoping to go swimming even through it is not summer yet or summer has passed, respectively. Since the heat capacity of water is about 4.2 J/g° C., and considering a pool with an average depth of 2.5 meters, if all the solar energy incident on the pool could be harnessed the pool could be heated by almost 4° C. per hour. This is more than enough heating for a pool owner to be able to utilize the pool for say an hour a day well into the off-seasons. (In fact, so much excess energy can be harvested that according to an alternate embodiment the system of the present invention incorporates a storage battery to store the excess in collected energy.)

The pool cover of the present invention has a flexible panel which has an upper sheet and a lower sheet, both of a flexible plastic material. The upper and lower sheets having essentially the same shape and size and are joined at their side edges to provide a waterproof seal. According to the present invention the upper sheet and the lower sheet are also joined along longitudinally-oriented seams to provide a series of flow channels. A pump connected to an input manifold at the front end of the panel forces water into the front end of the flow channels, and an output manifold at the rear end of the panel allows the output of water from the rear end of the flow channels. The system actively regulates the pool temperature to keep it within a specified range by monitoring the water temperature and/or the air temperature and/or the level of incident solar energy, and controlling pumping of the water through the flow channels to absorb heat from the ambient environment or release heat to the ambient environment.

Based on the above description of the background of the invention and the detailed description below, following are objects of the present invention.

It is an object of the present invention to provide a pool cover which is easy to use.

It is an object of the present invention to provide a pool cover which has a small volume when spooled onto an axle.

It is an object of the present invention to provide a pool cover which can efficiently harvest solar energy to warm pool water.

It is another object of the present invention to provide a pool cover which can efficiently cool pool water by transfer of heat energy in the water into the ambient environment, particularly at night when air temperature is lowest.

It is an object of the present invention to actively regulate the temperature of pool water through the generation of fluid flows based on one or more sensor measurements, such sensors monitoring a water temperature or multiple water temperatures, and/or ambient air temperature, and/or incident solar radiation.

It is another object of the present invention to provide a pool cover with water flow channels which produces efficient transfer of energy between the pool water and the ambient environment.

It is another object of the present invention to provide a pool cover with an input manifold to water flow channels in the cover which evenly distributes water flow between the flow channels.

Additional objects and advantages of the invention will be set forth in the description which follows, and will be obvious from the description or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of the pool cover of the present invention on a pool.

FIG. 2A is a cross sectional side view of a pool cover according to the present invention on the pool with an uptake tube which extends to near the bottom of the deep end of the pool.

FIG. 2B is a cross sectional side view of a pool cover according to the present invention on the pool with an uptake tube which extends to near the top surface of the pool.

FIG. 3 is an enlarged sectional end view showing the graduated aperture diameters of the input manifold utilized to achieve uniform flow rates across the flow channels.

FIG. 4 is a schematic of the electrical control system of the pool cover of the present invention.

FIG. 5 shows an interface for control of the settings of the temperature regulating pool cover of the present invention.

FIG. 6 is a flowchart showing the decision and control processes of the active temperature regulating pool cover of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to the lexicography of the present invention, a “pool” is considered to be any body of water or other liquid exposed to the ambient environment. That being said, the use of particular interest and that addressed most specifically herein is the temperature regulation of swimming pools.

FIG. 1 shows a top plan view of the pool cover (100) of the present invention on a pool (90). FIG. 2A shows a cross sectional side view of the pool cover (100) on the pool (99) according to a heating-functionality embodiment where a water uptake tube (210) extends to near the bottom of the deep region (92) of the pool (90). FIG. 3 shows a cut-away end view of the first three end-most flow channels (120.1), (120.2) and (120.3) of the pool cover (100).

The pool cover (100) of the present invention has a flexible panel (110) which can substantially cover the surface of the water (80) in the pool (90), as is shown in FIGS. 2A and 2B. The panel (110) has a flexible upper sheet (111a) and a flexible lower sheet (111b), as is shown in FIG. 3. The upper and lower sheets (111a) and (111b) are joined at side edges (109.1) and (109.2), shown in FIG. 1, and are joined along parallel, longitudinal-running seams (130.1), (130.2), (130.3), . . . to form a multiplicity of flow channels (120.1), (120.2), (120.3) . . . . (The seams will be referred to generically or collectively with reference numeral “130” and the flow channels will be referred to generically or collectively with reference numeral “120.”). The seams (130) and the seams at the sides of the sheets (111) are water-proof. Preferably, the sheets (111) are made of a uv-resistant, puncture-resistant 0.015 cm or 0.020 cm thick vinyl, and may possibly include reenforcement. It is advantageous to use materials which are as thin as possible for the upper and lower sheets (111a) and (111b) since the pool cover (100) needs to be retracted when the pool is in use, and that is typically accomplished by rolling the panel (110) up around a spool (not shown). Furthermore, it is advantageous to use as thin a material as possible for the upper and lower sheets (111a) and (111b) since flow of heat through the sheets (111a) and (111b) from top to bottom is inversely related to their thickness.

According to a preferred embodiment of the heating-functionality embodiment, the upper sheet (111a) is opaque and of a dark color, preferably a dark blue, to maximize absorption of incident solar radiation (60) and minimize reflection of incident radiation (60). Furthermore, the top surface of the upper sheet (111a) may be coated with an absorption-enhancing or anti-reflective coating in order to minimize reflected energy. As is well known in the art, anti-reflective coatings utilize destructive interference between energy reflected at the top and bottom surfaces of the coating to minimize reflected energy. The anti-reflective coating may be a powder or laminated film. According to the present invention, the thickness of the coating is therefore selected to correspond to the half wavelength of a frequency of light central to the range of frequencies providing the most incident energy. In particular, the coating has a thickness to create destructive interference for incident radiation with a wavelength of roughly 500 nm. (Wavelengths in the coating material will differ from wavelengths in a vacuum or the ambient environment because of the index of refraction of the coating material.) Furthermore, to maximize incident energy absorption, particles may be added to the material used to form the sheet (111a) or (111b) in the form of a filing, mixture, or modified compound, as well as threads, filaments, etc. Possible absorption-enhancing or anti-reflective materials include, but are not limited to, carbon black, aluminum, copper oxides and other metal oxides. Furthermore, such materials might also be used to increase thermal conductivity and affect heat capacity.

According to a preferred embodiment of the present invention, the material used to form the upper sheet (111a) (and possibly also the lower sheet (111b)) incorporates graphene because of a synergy of three properties of graphene which make it particularly useful for purposes and objects of the present invention. Graphene is an allotrope of carbon consisting of a single layer/plane of atoms having a two-dimensional honeycomb lattice arrangement. The material has an extremely high tensile strength, extremely high thermal conductivity in the plane of the atoms, and absorbs incident energy over a broad range of wavelengths. A panel of graphene is about 100 times stronger than would be a panel of steel of the same thickness, and is the strongest material known to man. Incorporating graphene in the material of the sheets (111a) and (111b) allows the thickness of the sheets (111a) and (111b) to be minimized so the panel (110), when wrapped around the spool, takes up a minimum of volume. Furthermore, graphene has thermal conductivity that may reach as high as 5300 W m⁻¹ K⁻¹. Although this upper limit to thermal conductivity may not be reached in practice without adding considerable expense to the manufacturing cost, realistic thermal conductivity values as high as 500 W m⁻¹ K⁻¹ to 600 W m⁻¹ K⁻¹ make the material useful for the present invention. Furthermore, the surprisingly high opacity of graphene, particularly in the visible and infrared frequency ranges, makes it an efficient absorber of incident solar radiation (60).

According to one preferred embodiment of the present invention, the lower sheet (111b) functions to provide insulation between the water (80) below the cover panel (110) and in the flow channels (120), while the upper sheet (111a) allows for heat transfer between the water (80) which flows through the channels (120) and the ambient air (70). If graphene is incorporated into the upper sheet (111a) in the form of relatively large planes of the material, the planes should extend to some extent in the direction from the upper surface of the upper sheet (111a) to the lower surface of the upper sheet (111a). If graphene is incorporated into the upper sheet (111a) in the form of a relatively fine powder, then the randomness of the orientations of the grains of the powder will insure that a portion of the grains will have an orientation so as to provide thermal conductivity between the upper and lower surfaces of the upper sheet (111a). If graphene is incorporated into the lower sheet (111b) in the form of relatively large planes of the material, then the planes should extend substantially parallel to the upper and lower surfaces of the lower sheet (111b) so the lower sheet (111b) will have a low thermal conductivity between its top and bottom surfaces.

According to one preferred embodiment of the present invention, the upper sheet (111a) is transparent and the lower sheet (111b) is opaque and of a dark color, preferably a dark blue, in order to absorb a large portion of the incident radiation (60). The advantage of this embodiment is that the heat energy exiting the heat-absorbing sheet (in this case the lower sheet (111b)) is useful when exiting in both the upwards and downwards directions. Heat exiting upwards heats the water (90) flowing through the flow channels (120), and heat exiting downwards heats the water (90) just under the pool cover. The top surface of the lower sheet (111b) may be coated with an absorption-enhancing or anti-reflective coating in order to minimize reflected energy having a wavelength central to the range of frequencies providing the most incident energy, i.e., roughly 500 nm.

Because the water (80) in the pool (90) is coldest in the deep region, and because the energy transfer is proportional to the temperature differential and therefore most efficient when there is a large temperature differential, the pumping system (200) pumps water up from the deep region (92) of the pool (90), the pumping system (200) has a flexible uptake tube (210) which has a length comparable to or greater than the depth of the deep region (92) of the pool (90) in order to pump water (80) from the deep region (92). The upper end (211) of the uptake tube (210) flow connects to an input manifold (220), and the input manifold (220) flow connects to the input edge (109.3) of the panel (110). (According to the lexicography of the present specification, a first component is said to “flow connect” to a second component when water channeled through the first component is forced into the second component with little to no leakage elsewhere.) Pool water (80) pumped through the flow channels (120) picks up heat from the panel (110) as it travels the length of the flow channels (120) before emptying into the pool (90) at the end (109.4) of the panel (110) opposite the input manifold (220). According to the preferred embodiment of the present invention, the pump (230) is a portable low-flow fractional horsepower water pump and is powered by a solar panel (240) mounted on the top of the input manifold (220). (Alternatively, the pump (230) is powered by a chord connected to a standard wall socket electrical outlet or by a battery.)

The input manifold (220) has a series of input manifold apertures (225.1), (225.2), (225.3) . . . with inter-aperture spacing equal to the widths of the flow channels (120). (The input manifold apertures will be referred to generically or collectively with reference numeral “225.”) The pump (230) along the uptake tube (210) draws water in at the lower end (211) of the uptake tube (210) and forces it out the upper end (212) of the uptake tube (210), into the input manifold (220), through the manifold apertures (225), and into and along the flow channels (120). Water pressure decreases along the length of the input manifold (220) in the rightwards direction so, as can be seen by the exaggerated differences in the diameters of the input manifold apertures (225) in FIG. 3, the diameters of the input manifold apertures (225) increase from left to right. This insures that the water flow is even distributed across the flow channels (120), i.e., roughly an equal amount of water flows through each flow channel (120), in order to maximize heat transfer from solar radiation incident on panel (110) to the water (80) in the pool (90).

In one preferred embodiment of the present invention the pool cover (100) has an on-off switch (301) and the user simply turns it on when it is desired that the temperature of the water (80) be increased and the ambient conditions (i.e., air temperature, water temperature, and incident radiation) make heating of the water (80) possible. According to a more sophisticated embodiment, the system further includes one or more temperature sensors and a processor. A schematic (400) of the electrical control system for the active pool water temperature control system according to a more sophisticated embodiment is shown in FIG. 4. (The electrical connection wirings between the various electrical components are depicted in FIG. 4 but for the sake of clarity of depiction the wirings are not depicted in the other figures.) According to the present invention, the control system (400) may have a deep water temperature sensor (310) mounted on the uptake tube (210) near its bottom end (211), a surface water temperature sensor (320) mounted on the uptake tube (210) near its upper end (212), an air temperature sensor (423) mounted on the top side of the input manifold (220), a light meter (424) also mounted on the top side of the input manifold (220), and a processor (410) mounted on the input manifold (220). In one preferred embodiment, the control system (400) further includes a solar panel (240) to convert incident solar radiation (60) into electrical energy to power the processor (410) and the pump (230). (It is assumed that the on/off switch (301), deep water temperature sensor (310), surface water temperature sensor (320), air temperature sensor (423), and light meter (424) are passive components, although these may alternatively be powered components.)

The control system (400) utilizes temperature monitoring via one or more sensors (310), (320), (423) and (424) to control the pumping performed by the pump (230). (It should be noted that the pool cover (100) of the present invention which is utilized, as described above to absorb daytime solar energy (60) to heat the pool water (80), may also be used to transfer the heat energy of pool water (80) to the ambient environment (70), particularly at night.) According to a preferred embodiment of the present invention, programming and control of the processor (410) is implemented via an app on a mobile phone which communicates with the processor (410) via a blue tooth interface. The implementation of mobile phone apps is well-known in the art of mobile phone application programming. According to the preferred embodiment, a user may utilize the app to specify variables such as a target temperature or a target temperature range for the pool water (80), and/or may schedule pumping based on a clock (412) incorporated in the processor (410), and/or may access weather data, such as predicted air temperature or cloudiness as a function of time, via an Internet connection (not shown in FIG. 4) to schedule the functioning of the system (100) for optimum performance and efficient energy usage.

According to an embodiment of the present invention which functions predominantly to lower the water temperature, the temperature of the water (80) in the pool (90) is lowered by reducing the amount of solar energy (60) reaching the water (80), and/or providing insulation between the water (90) and the ambient air (70), and/or facilitating heat transfer to the ambient air (70) when the air (70) is cooler. According to this cooling-functionality embodiment, the upper sheet (111a) is highly reflective of incident solar radiation (60). Such reflectivity may be achieved by the use of films and coatings such as is well known in the art, such as the art of films and coatings commonly applied to the windows of buildings to reflect solar energy, or the top surface of the upper sheet (111a) may be “metallized”, such as with aluminum, silver, titanium, metal oxides, etc.

As with the heating-functionality embodiment described above, the pool cover (100) has a flexible panel (110) which can substantially cover the surface of the water (80) in the pool (90), as is shown in FIG. 1. The panel (110) has a flexible upper sheet (111a) and a flexible lower sheet (111b). Preferably, the sheets (111) are made of a uv-resistant, puncture-resistant 0.015 cm or 0.020 cm thick vinyl. It is generally advantageous to use materials which are as thin as possible for the upper and lower sheets (111a) and (111b) since the pool cover (100) needs to be removed from covering the water (80) when the pool is in use, and that is typically accomplished by rolling the panel (110) up around a spool (not shown). The upper and lower sheets (111a) and (111b) are joined at side edges (109.1) and (109.2) and are joined along parallel, longitudinal-running seams (130.1), (130.2), (130.3) . . . . to form a multiplicity of flow channels (120.1), (120.2), (120.3) . . . . (The seams will be referred to generically or collectively with reference numeral “130” and the flow channels will be referred to generically or collectively with reference numeral “120.”) The seams (130) and the seams at the sides of the sheets (111) are water-proof.

According to a preferred embodiment of the present invention, the lower sheet (111b) functions to provide insulation between the water (80) and the air (70), while the upper sheet (111a) allows for heat transfer between the water (80) which flows through the channels (120) and the ambient air (70). According to a preferred embodiment, the material used to form the upper sheet (111a) incorporates graphene in the form of a filing, mixture, or modified compound, or in the form of graphene threads, filaments, etc. because of a synergy of properties of the material which make it particularly useful. Because of graphene's extremely high tensile strength, incorporating it in the material of the upper sheet (111a) allows the thickness of the sheet (111a) to be minimized, which is advantageous since the rate of conduction of heat through the upper sheet (111a) is inversely related to its thickness. And the high thermal conductivity of graphene further facilitates the transfer of heat from the water (80) which flows through the flow channels (120) to the ambient air (70).

If graphene is incorporated into the upper sheet (111a) in the form of relatively large planes of the material, the planes should extend to some extent in the direction from the upper surface of the upper sheet (111a) to the lower surface of the upper sheet (111a). If graphene is incorporated into the upper sheet (111a) in the form of a relatively fine powder, then the randomness of the orientations of the grains of the powder will insure that a portion of the grains will have an orientation so as to provide thermal conductivity between the upper and lower surfaces of the upper sheet (111a). If graphene is incorporated into the lower sheet (111b) then the planes of the graphene atoms must extend substantially parallel to the upper and lower surfaces of the lower sheet (111b) to provide a low thermal conductivity from the top surface to the bottom surface of the lower sheet (111b).

In an alternate embodiment graphene is not utilized to reduce the thickness of the sheets (111a) and (111b). To allow the pool cover (100) of the present invention to be stored at the edge of the pool (90) in the space generally provided for a traditional pool cover, the size of the pool cover (100) when rolled up is minimized by using a mechanism to squeeze water and air out from the flow channels (120) and from between the space between the outside surfaces of the sheets (111a) and (111b) when the pool cover (100) is in its rolled-up state. The mechanism to accomplish this may provide additional longitudinal and/or transverse tensioning during the rolling-up process. Furthermore, the longitudinal seams (130) may run askew from the longitudinal axis of the pool cover by a small angle ß so that when rolled up the stitchings of the seams (130) do not overlap from layer to layer in order to minimize the diameter of the rolled-up pool cover (100).

A pumping system (200′) has a short flexible uptake tube (210′) so it (200′) pumps water from near the top surface (94) of the pool (90), where the water (80) is warmest, through the flow channels (120). The upper end (212) of the uptake tube (210′) flow connects to the input manifold (220), and the input manifold (220) flow connects to the input edge (109.3) of the panel (110). As described above, the input manifold (220) has a series of manifold apertures (225.1), (225.2), (225.3) . . . with inter-aperture spacing equal to the widths of the flow channels (120). A pump (230) draws water in at the lower end (211′) of the uptake tube (210′) and forces it out the upper end (212) of the uptake tube (210), into the input manifold (220), through the manifold apertures (225), and into and along the flow channels (120). As described above, the diameters of the manifold apertures (225) increase from left to right to insure that roughly an equal amount of water flows through each flow channel (120) in order to maximize heat transfer from the panel (110) into the ambient environment (70). The pump (230) is preferably a portable low-flow fractional horsepower water pump and is powered by a solar panel (240) mounted on the top of the input manifold (220). (Alternatively, the pump (230) is powered by a chord connected to a standard wall socket electrical outlet or by a battery.)

In one preferred embodiment of the present invention the pool cover (100) has an on-off switch (301) and the user simply turns it on when it is desired that the temperature of the water (80) be reduced. But according to a more sophisticated embodiment, the system utilizes the electrical control system (400) of FIG. 4 except that there will not be deep water temperature sensor (310). The system (400) utilizes temperature monitoring via one or more of the sensors (320), (423) and (424) to control the pumping performed by the pump (230).

As described above for the heating-functionality embodiment, according to a preferred embodiment of this cooling-functionality embodiment programming and control of the control processor (410) is implemented via an app on a mobile phone which communicates with the control processor (410) via a blue tooth interface. A user may utilize the app to specify variables such as a target temperature or a target temperature range for the pool water (80), and/or may schedule pumping based on a clock (412) incorporated in the processor (410), and/or may access weather data, such as predicted air temperature or cloudiness as a function of time, via an Internet connection (not shown in FIG. 4) to schedule the functioning of the system (100) for optimum performance and efficient energy usage.

A control interface (500) for the pool cover temperature regulating system of the present invention is shown in FIG. 5. The interface has an on-off switch (501), a time slots settings section (505), and a target temperature section (550). The master on-off switch (501) can be switched from an on setting when the control button (502) is to the left (as is depicted in FIG. 5) to an off setting by sliding the control button (502) rightwards. Similarly, when the system is off and the control button (502) is rightwards, the control button (502) can be swiped leftwards to turn the system on. The time slots settings section (505) has three time control slots (510), (520) and (530). Each time control slot (510), (520) and (530) allows for control of the beginning time and ending time of temperature regulation by the system, has an auto-retract switch (516), (526) and (536) to control whether the cover is retracted at the end of a time slot, and has an on-off button (511), (521) and (531) to switch between making that time control slot (510), (520) and (530) active and inactive. Each time slot (510), (520) and (530) has a start time control (512), (522), and (532) and an end time control (513), (523) and (533). The start and end times of each time slot (510), (520) and (530) can be set by the user by scrolling up and down on the hour and/or minutes and or AM/PM selection (similar to how, for instance, alarm times are set on an iPhone made by Apple Computers of Cupertino, Calif.). Although the interface (500) is depicted as having three time slot settings sections (510), (520) and (530), according to the present invention the interface (500) may have more or less than three slot settings sections. Below the time period control section (505) is a temperature control section (550) which allows a target temperature and a target temperature range to be set. The target temperature is set by scrolling the temperature value displayed in the target temperature window (551) upwards or downwards, and the target temperature range is set by scrolling the temperature range value displayed in the target temperature range window (552) upwards or downwards. In FIG. 5, the target temperature is 83° F. and the range is +/−1.3° F. so if the ambient environment can provide sufficient heat and/or cool while the system is active the temperature of the pool (90) stays between 81.7° F. and 84.3° F.

The advantage of having multiple time control slots is illustrated, for instance, by an exemplary situation where the system is used for the pool of a family where, on most weekdays, the children have from shortly after they get home from school at 3:30 pm to shortly before dinner at 5:30 pm to use the pool. The start time in the start time window (512) of the first time control section (510) is set to 8:00 am, which is when the sun in this exemplary situation is high enough that solar radiation can begin to efficiently provide heating. Since the auto-retract switch (526) of the 5:30 pm to 7:30 pm time period (520) (which was the last time slot of the day chronologically) is in the off position, at 8:00 am the pool cover (100) remains extended after having been in the extended position overnight, possibly for the purpose of preventing overnight heat loss. At 8:00 am, the beginning of the first time slot (510) of the day, the system activates the pump (230) and heating of the pool (90) begins. The time in the end time window (513) of the first time slot (510) is set to 3:30 pm, which is when the children have gotten home from school and may use the pool (90). Since no other active time period abuts or overlaps this time, pumping of the pump (230) ceases and the pool cover (100) retracts since the control button (517) of the auto-retract switch (516) of the first time slot (510) is in the on position. (It should be noted that the control button (535) of the on-off switch (535) of the third time slot (530) is in the off position, so there is no temperature control for the period from 3:30 pm to 5:30 pm.) The system having been in operation from 8:00 am to 3:30 pm, the temperature of the pool (90) is hopefully within the target range of temperature 83° F. +/−1.3° F. and the children enjoy a comfortable water temperature during their swim. In this exemplary situation the children are required to get out of the pool (90) shortly before their dinner time at 5:30 pm, and at 5:30 pm the second time period begins since the time in the start time window (522) of the second time slot (520) is set to 5:30 pm. The system therefore extends the cover (100) over the pool (90) and activates the pump (230), and utilizing the last of the reasonably-strong sunlight of the day the heating of the pool (90) continues. The time in the end time window (523) of the second time period (520) is set to 7:30 pm, which is when solar radiation during the time of year in this exemplary situation has diminished to an extent that it is not energetically worthwhile to continue operation of pump (230) of the temperature control system. Therefore, pumping of water through the pool cover (100) ceases at 7:30 pm, and because the control button (527) of the auto-retract switch (526) is in the off position, the pool cover (100) stays extended overnight. This may provide the benefit of preventing heat loss to the cold ambient air during the night.

On days when the children have other activities, such as baseball or soccer games or practices, they will not be home to swim during the time gap between the periods specified in the first and second time slots (510) and (520). And such days a parent may simply swipe the control button (535) of the on-off switch (531) of the third time control period (530) leftwards to activate heating during the gap between the end of the first time slot (510) and the beginning of the second time slot (520) when the children would normally be using the pool. Because the end of the first time slot (510) abuts the beginning of the third time slot (530), the pool cover (100) does not retract, but instead remains extended and the system continues to utilize solar radiation to heat the pool (90) during the third time slot (530).

A flowchart showing the decision and control process (600) of the system of the present invention is shown in FIG. 6. The process (600) begins (601) by first determining (605) whether the control button (502) of the on-off switch (501) is in the on position. If not (606), the process (600) returns (670). If so (607), the pool temperature sensor (310) is monitored to determine whether the current temperature is within the range specified in the target temperature section (550) of the control interface (500). If so (612), the process (600) returns (670). If not (611), it is then determined (615) whether the current time is within a specified time range of any of the active time slots (510), (520) and (530), i.e., any of the time slots (510), (520) and (530) where the control button (515), (525) and (535) of the on-off switch (511), (521) and (531) is in the on position. If not (616), it is determined (680) whether the pool cover (100) should be retracted. As described above, this will depend on whether the time slot (510), (520), or (530) which has a time period which most recently ended had the control button (517), (527) or (537) of its auto-retract switch (516), (526) or (536) in the on position and whether the pool cover (100) had not yet been retracted. If so (682), the pool cover (100) is retracted (685) and the process (600) returns (670). If not (681), the process (600) simply returns (670). If it is determined (615) that the current time is (617) within a time range specified by of any of the active time slots (510), (520) and (530), it is then determined (620) whether the pool cover (100) is extended. If not (621), the pool cover (100) is extended and the process (500) proceeds to step (630). If so (622), the process (500) proceeds directly to step (630). At step (630) it is determined whether the pool temperature is less than the bottom of the target temperature range specified in the target temperature section (550) of the control interface (500). If so (632), then it is determined (650) whether the air temperature as measured by the air temperature sensor (423) and the incident solar radiation as measured by the light meter (424) are sufficiently high to allow pumping of water through the pool cover (100) to heat the pool (90). If so (651), pumping (660) is initiated. If not (652), the process (600) returns (670). If at step (630) it is determined that the pool temperature is not (631) less than the bottom of the target temperature range, then it is determined (635) whether the pool temperature is greater than the top of the target temperature range specified in the target temperature section (550) of the control interface (500). If not (636), then the temperature of the pool (90) is within the desired temperature range and the process (600) returns (670). If so (637), then it is determined (640) whether the air temperature as measured by the air temperature sensor (423) and the incident solar radiation as measured by the light meter (424) are low enough to allow pumping of water through the pool cover (100) to cool the pool (90). If so (641), pumping (660) is initiated. If not (642), the process (600) returns (670).

Hence, a water temperature regulating pool cover performing the above-described objects and providing the above-described advantages is taught. It is to be understood that the foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and it should be understood that many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable those skilled in the art to best utilize the invention and the various elements of the embodiments, alone or in any combination, with various modifications as are suited to the particular use contemplated. Hence, many other variations are possible. For example: thin-film photovoltaic solar electric ribbons or panels attached to the top sheet may be utilized to generate the electricity for the pump and/or processor; features of the above-described heating system may be combined with features of the above-described cooling system, or vice versa; the system may not actively monitor water temperature; the channels may be wider or narrower than described; the materials of the top and bottom sheets may be different from what is described; the sheets may have a thickness smaller or larger than what is described; the top sheet of the pool cover panel may be clear and the bottom sheet may be a dark color to absorb incident solar radiation; the pump may be located elsewhere along the uptake tube, such as nearer the sheet; water may be input to the input manifold from both ends rather than a single end; the flow channels may having differing widths; the panel of the pool cover may have more or fewer flow channels that shown and described above; the flow channels may be oriented transversely, rather than longitudinally, i.e., across the width of the pool rather than the length of the pool; the sheets may be thinner or thicker than described; the system may allow the user to control more or less than three time slots; the system may allow for different target temperatures for each time period; extension and retraction of the pool cover may not be controlled by the system and, rather, may be performed manually; the system may include a control system of more or less sophistication than that described; the control system may select water from a variety of depths based on temperature variation within the pool; the system may utilize weather predictions and/or seasonal information such as local sunrise and sunset times; etc. Furthermore, a hybrid embodiment incorporating features of both the heating functionality and the cooling functionality are possible. For instance, there may be a pump at one longitudinal end of the panel with an inlet near the upper surface of the water and another pump at the other longitudinal end of the panel with an inlet near the bottom of the deep end of the pool. This hybrid embodiment may have some flow channels adapted for heating the pool water and some flow channels adapted for cooling pool water. Accordingly, it is intended that the scope of the invention be determined not by the embodiments illustrated or the physical analyses motivating the illustrated embodiments, but rather by the appended Claims and their legal equivalents.

Claims

1. A pool cover for temperature regulation of pool water, comprising: a flexible panel having an upper sheet of flexible material having a front edge, a back edge, and side edges, a lower sheet of flexible material having a front edge, a back edge, and side edges, said side edges of said upper sheet and said lower sheet being joined to provide a waterproof seal, said upper sheet and said lower sheet being joined at a plurality of seams to form flow channels between said seams,a cover input manifold, said input manifold being flow connected to said front edge of said flexible panel, said input manifold having an input aperture for each of said flow channels,a pump for pumping water through said input manifold and into said channels to produce water flow from front edges of said flow channels to back edges of said flow channels, andan uptake tube for drawing water from said pool to said pump, whereby temperature of water flowing through said flow channels is altered by contact with said upper sheet which is in thermal contact with an ambient environment.

2. The pool cover of claim 1 wherein said flow channels are substantially parallel.

3. The pool cover of claim 2 wherein said flow channels have longitudinal axes substantially aligned with a longitudinal axis of the pool cover.

4. The pool cover of claim 1 wherein sizes of said apertures provide substantially equal flow through each of said channels.

5. The pool cover of claim 1 wherein said uptake tube has sufficient length to extend to a lower region of said pool in order to draw cooler temperature water into said pump.

6. The pool cover of claim 5 further including means for drawing warmer temperature water from an upper region of said pool into said pump.

7. The pool cover of claim 1 further including: a first sensor for determining a first temperature of said pool water;means for determining ambient heat conditions;a processor for controlling functioning of said pump based on said first temperature of said pool water, said ambient heat conditions, and a target temperature for said pool water.

8. The pool cover of claim 7 wherein said means for determining said ambient heat conditions is a temperature sensor for determining an ambient air temperature.

9. The pool cover of claim 7 wherein said means for determining said ambient heat conditions is an incident radiation sensor for measuring incident solar radiation.

10. The pool cover of claim 7 further including a control interface for allowing a user to specify said target temperature for said temperature regulation of said pool water.

11. The pool cover of claim 10 wherein said control interface allows said user to set a first time period during which said pump operates for said temperature regulation of said pool water.

12. The pool cover of claim 11 wherein said control interface allows said user to set a second time period during which said pump operates for said temperature regulation of said pool water.