Abstract:
A liquid level control system utilizes a sensor that is attached to a fixed support relative to a liquid container and transmits radio-frequency signals to a remotely located liquid supply system depending upon fluctuations in the liquid level. In the context of a swimming pool, the sensor housing is attached to a sidewall of the pool, at the desired water level. A sensor circuit located within the housing floats at the liquid level, and as changes occur, movement of the floating sensor results in the transmission of signals to either activate or deactivate a supply valve that supplies replacement water to the pool. A small opening located at an upper portion of the sensor housing cooperates with the floating sensor to dampen the motion of the sensor, providing a more accurate reading of the liquid level.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application, Ser. No. 60/113,767, filed Dec. 23, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to the general field of liquid containers and, more particularly, to control systems for maintaining a liquid level within such containers. More specifically, the present invention relates to a control valve and remote sensor system for regulating the fill level in a swimming pool or similar liquid container. 
     2. Description of the Prior Art 
     Modern technology has in many ways simplified the problem of swimming pool upkeep. The availability of more sophisticated chemical treatments, as well as the use of modern skimmers, recirculators, and filtering apparatus, have significantly lessened the manual labor required to maintain sanitary and esthetically pleasing swimming pools. For these technologies to work, however, it is necessary to keep the water level of a swimming pool within a relatively narrow range. 
     In the past, visual references have been relied upon to maintain the water level within a swimming pool. Upon observing a decrease in the water level, a supply of makeup water would be provided, frequently by manually operating a water control valve. Since even a slightly a low water level can require a large restorative volume, domestic water systems may require several hours before the water level has been restored. This time factor alone makes this task unpleasant, with inattention resulting in over filling, or worse, flooding the surrounding pool area. 
     The desirability of providing automatic means for maintaining the water level in swimming pools has long been appreciated. Without the need for manual supervision or intervention, the water level of a swimming pool would be maintained within the required maximum and minimum limits. 
     Systems for monitoring and controlling the water level in a swimming pool or other fluid reservoir are well known to the art. The majority of such systems are not suitable for use in retrofitting in-ground pools, requiring a significant amount of structural modifications to the pool deck and/or the pool walls. In addition to being difficult to install, such conventional water leveling systems are frequently costly to maintain. They often include moving parts that, because of their continual contact with water, are extremely susceptible to damage caused by fatigue corrosion and the accumulation of calcium and other mineral deposits. 
     Other conventional water leveling systems utilize floats, which are susceptible to corrosion and to failure as a result of the accumulation of calcium and other mineral deposits. Installation of float systems in existing swimming pools also normally requires additional concrete construction (and destruction) as portions of existing pool walls and pool decks are replaced. Until recently, the use of electrical sensors in water level control systems has encountered resistance in implementation due to safety considerations. 
     In addition to the problems inherent in retrofitting a complex sensor and water control unit adjacent an existing pool, there are also the previously mentioned safety concerns regarding those designs that use electrical communication between the sensor and the control valve unit(s). The need thus exists for a swimming pool water level control system that can be quickly and inexpensively installed and maintained on existing swimming pools. A further advantage would be obtained by utilizing a design that minimizes the opportunities for electrical shock hazards during operation of the water level controller. 
     SUMMARY OF THE INVENTION 
     The present invention provides an automatic liquid regulation system that can be used to maintain a desired liquid level in a container, such as the desired water level in a swimming pool. A remote sensor is placed in the container/pool, and monitors changes in the liquid level therein. At such time as the liquid level falls below a desired level, the sensor detects such a drop, and transmits a signal to a remotely located supply valve to open and permit the flow of additional liquid into the container/pool. Once the desired level is again achieved, a supplemental signal causes the supply valve to close, terminating the fill operation. 
     It is an object of the present invention to provide an automatic liquid level regulator that can be easily placed within a liquid container in a manner requiring no particular receiving structure or any connections to an existing power supply. As such, retrofitting a liquid level control system to existing containers is particularly enabled utilizing the sensor of the present invention. 
     It is an additional object of the present invention to provide an automatic liquid level regulator that can be removably attached to a sidewall of a liquid container, such as the side of a conventional in ground swimming pool. 
     It is a further object of the present invention to provide an automatic liquid level regulator that maintains the liquid level within a container, such that a fall in the liquid level below a predetermined level results in the activation of a fill valve to cause the flow of liquid into the container until reaching a predetermined liquid level within the container, whereupon deactivation of the fill valve occurs. 
     In this regard, an outer housing containing the sensor is placed against the sidewall of the liquid container. The liquid level sensor is provided a separate housing that is slidably received within the outer housing. Liquid is permitted entry into the outer housing upon its placement in the container, with the sensor housing being “floated” by such liquid within the outer housing. 
     Upon placement of the outer housing at the liquid level within the container, subsequent changes in that level result in movement of the sensor housing relative to the outer housing. Such movement is utilized in the present invention to activate mechanical switches, which in turn result in the transmission of radio-frequency signals to a remotely located supply valve. Such valving controls liquid for replenishment of the container, and its activation in accordance with the movement of the sensor housing is utilized in the present invention to automatically control the liquid level in the container. 
    
    
     Further objects and advantages of the present invention shall become apparent from the ensuing description and as illustrated in the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevation view showing an outer housing for a water level detector in accordance with the present invention; 
     FIG. 2 is a rear elevation view, similar to FIG. 1, showing a manner of attachment provided the outer housing in accordance with the present invention; 
     FIG. 3 is a top plan view, with portions in phantom, showing an outer housing for a water level sensor in accordance with the present invention; 
     FIG. 4 is a bottom plan view, similar to FIG. 3, showing an open bottom provided in an outer housing for a water level sensor in accordance with the present invention; 
     FIG. 5 is a side elevation view, in cross-section, showing the interior portions of a water level sensor in accordance with the present invention; 
     FIG. 6 is a side elevation view, in cross-section, showing a water level sensor as received within an outer housing in accordance with the present invention; 
     FIG. 7 is a partial side elevation view, in cross-section, showing a water level controller receiver unit in accordance with the present invention; 
     FIG. 8 is a partial representational view showing a remotely located control valve in accordance with the present invention; 
     FIG. 9 is a partial perspective view, with portions broken away and portions schematically depicted, showing a water level control system in accordance with the present invention; 
     FIG. 9A is an enlarged side elevation view, with portions broken away and portions in phantom, showing the manner in which a water level sensor in accordance with the present invention interacts with the water level existing in a swimming pool in accordance with the present invention; 
     FIG. 10 is an exploded perspective view showing an alternate liquid level sensor and outer housing in accordance with the present invention; 
     FIG. 11 is a perspective view of the alternate sensor and housing of FIG. 10 shown positioned to monitor a liquid level in accordance with the present invention; and 
     FIG. 12 is a partial side elevation view, with portions in phantom, showing the liquid level sensor of FIGS. 10 and 11 at separate liquid levels in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference is now made to the drawings wherein like numerals refer to like parts throughout. An outer housing  10  is shown in FIG. 1 having a pair of suction cups  14  attached to a lateral side thereof. A reference probe  16  is also shown attached to a lateral side of the housing  10 , the purpose of which will be discussed hereinafter. 
     In a presently preferred embodiment, the outer housing  10  is cylindrical, and is provided an upper cover  18  that is attached to and sealing a first end and a lower cover  19  attached to and sealing a second end. A liquid passageway  22  is formed in the cover  18 , permitting entry of the water or other liquid during operation of the water level controller of the present invention. 
     When in the cylindrical form depicted in FIG. 1, the cylindrical housing  10  is preferably installed with the longitudinal axis in a vertical orientation. FIG. 2 illustrates such positioning, as well as the manner in which the suction cups  14  are arranged in a superposed relation. Additionally, although so depicted in FIGS. 3 and 4, there is no requirement that the liquid passageway  22  be concentric with the central longitudinal axis. The function of air pressure equilibrium can be obtained so long as the liquid passageway  22  is formed in the lower cover  19  at any radial location inside of an inner housing wall  26 . 
     FIG. 5 shows a presently preferred embodiment of a water level sensor  32 . A power unit  34  is shown as separable from a transmitter unit  36 . A dry cell battery  38  is received within a conventional electric contact-retaining clip  42 . Enabling the detachment of the power unit  34  from the transmitter unit  36  greatly simplifies access to the dry cell battery  38  when replacement is required. A pair of power supply conductors  44  communicates electrical power from the dry cell battery  38  to the transmitter unit  36 . 
     It is to be understood and appreciated that other options exist for conducting power supplied by the power unit  34  to the transmitter unit  36 . One such method would provide opposing electrical contacts (not shown in the Figures) that abut one another on such occasions as the power unit  34  is fully received within the transmitter unit  36 . Other electrical pathways can be created utilizing known techniques without departing from the teachings of the present invention. 
     To prevent corrosion as well as electrical shorting problems is preferable that a watertight connection be established between the power unit  34  and the transmitter unit  36 . Here also, a number of different connections are possible to obtain such a sealed fit. In FIG. 5, a spiral sequence of tightly spaced threads  48  are received within a correspondingly scored cylindrical wall  52  that terminates in a replaceable, resilient sealing ring  54 . 
     The transmitter unit  36  is defined by a cylindrical outer wall  62  that has a vertically oriented receiving slot  64  formed in a lateral portion thereof. The inadvertent entry of liquid through the receiving slot  64 , a flexible slot membrane  65  is attached about the periphery of the receiving slot  64 , and extends into the transmitter unit  36 . 
     A pair of opposing electrical contacts switches  66   a,    66   b  are attached to the outer wall  62 , each at a location adjacent a separate terminus of the receiving slot  64 . In this manner, the pair of contact switches  66   a,    66   b  is vertically superposed in relation to one another. A pair of electrical connectors  68   a,    68   b  are each attached to a respective one of the pair of contact switches  66   a,    66   b,  and to a transmitter circuit  72 . The making and/or breaking of an electrical contact by the pair of electrical contact switches  66   a,    66   b  is communicated by the pair of electrical connectors  68   a,    68   b  to the transmitter circuit  72 . 
     Placement of the water level sensor  32  within the outer housing  10  is depicted in FIG.  6 . The water level sensor  32  is so positioned as to place the receiving slot  64  of the outer wall  62  adjacent the reference probe  16 . This in turn permits the reference probe shaft  28  of the reference probe  16  to be received by the receiving slot  64  and project into the water level sensor  32 , while remaining inside of the flexible slot membrane  65 . 
     The reference probe shaft  28  extends (within the flexible slot membrane  65 ) between the pair of contact switches  66   a,    66   b,  which are both provided with a switch contact lever  76  that projects in a direction toward the reference probe shaft  28 . The water level sensor  32  is received within the outer housing  10  in a manner that permits movement along the lateral axis of the outer housing  10 . The receiving slot  64  is sufficiently elongated along the lateral axis of the outer housing  10  to permit movement of the reference probe shaft  28  relative to the positioning of the water level sensor  32 . 
     The electrical contact switches  66   a,    66   b  are placed adjacent the receiving slot  64  in a manner that defines two transitional switch positions. A first position results in deflection of a first switch contact lever  76   a  of the first contact switch  66   a,  with movement to a second, subsequent lateral position resulting in the deflection of a second switch contact lever  76   b  of the second electrical contact switch  66   b.  In this manner, changes in the relative position of the inner housing  32  within the outer housing  10  are utilized to activate one or both of the electrical contact switches  66   a,    66   b.    
     Electrical switch activation results in the transmission of a signal from the electrical contact switches  66   a,    66   b  through the electrical connectors  68 , to the transmitter circuit  72 . A signal (not shown in FIG. 6) is then transmitted, for receipt by a receiver antenna  82  shown in FIG.  7 . The transmitted signal is then communicated through a receiving wire  84  to a receiver circuit  86  that is located within a receiving housing  88 . A power supply  92  provides electrical power to the receiver circuit  86  and one or more activation wires  94  (only one set shown in FIG. 7) are provided to communicate activation signals from the receiver circuit  86  to one or more electrical devices (not shown in FIG.  7 ). 
     In FIG. 8, a pair of activation wires  94  is shown terminating in an actuator valve assembly  98 . Upon receipt of an electrical signal through the activation wires  94 , a solenoid  101  within the valve assembly  98  is activated, causing movement of a valve assembly  105  to which the solenoid is mechanically attached. A water supply conduit  111  is connected to a first side of the valve assembly  105 , with a water discharge conduit  113  is connected to a second side thereof. The selective activation of the solenoid  101  by signals provided through the activation wires  94  permits control of water flow through the actuator valve assembly  98  by controlling the positioning of the valve assembly  101 . 
     The overall manner in which the level controller of the present invention operates is generally depicted in FIG. 9. A water level controller  121  is shown attached to a sidewall  123  of a swimming pool  125 . Pool water  127  forms a water level  131 . The water level controller  121  is so located on the pool side wall  123  that when the desired water level  131  is achieved, the reference probe shaft  28  lies between the pair of switch contact levers  76  without activating either (see FIG. 9 a ). 
     Upon a change in the water level  131 , for example a drop due to evaporation of the pool water  127 , the water level sensor  32  moves downward within the outer housing  18  (shown in phantom as the transmitter unit  36   b  in FIG.  9 A). This in turn results in the reference probe shaft  28  making contact with the lower switch contact lever  76   b.  The transmitter circuit  72 , causing activation of the solenoid  101  and the valve assembly  105  of the actuator valve assembly  98  generates a radio-frequency signal  135 . Opening of the valve assembly  105  then permits water from the water supply conduit  111  to flow out the water discharge conduit  113  and into the swimming pool  125 . 
     As the water continues to flow into the swimming pool  125 , the water level  131  will rise, resulting in a rising of the water level sensor  32  within the outer housing  10  of the water level controller  121 . The reference probe shaft  28 , which is attached to the outer housing  10 , will move from its position adjacent the upper switch contact lever  76   a,  until the continued rising of the water level  131  results in a deflection of the lower switch contact lever  76   b,  and the subsequent generation of another radio frequency signal  135 . Upon receipt of this second signal, the solenoid  101  is again activated, this time to close the valve assembly  105  and shut off the flow of water through the actuator valve assembly  98  and through the water discharge conduit  113 . Water is then no longer being supplied to the swimming pool  125  until a lowering of the water level  131  causes this activation cycle to begin again. 
     As the transmitter unit oscillates between the maximum and minimum water levels, the distance traveled (shown as reference letter A) is equal to the distance between the distance the reference probe shaft  28  travels between the pair of switch contact levers  76   a,    76   b  (shown as reference letter B). The manner in which the water level sensor  32  fits within the outer housing  10 , and the absence of air passageway in the upper cover  18  is made use in the present invention as a dampener. By resisting the instantaneous movement of the water level sensor  32 , caused by the movement of swimmers and the like, the present invention lessens the “false alarm” response to temporary changes in water level. 
     In a presently preferred embodiment, the transmitter circuit is provided a timing circuit that ends the transmission of a signal after an appropriate period of time. Specifically, once the signal is sent to the receiving unit, it will continue for only a short period to time to ensure its receipt, and then will end. To continue this signal for so long as the switch contact lever remains depressed will result in more rapid battery exhaustion. Once the pool has been filled, the other switch contact will be depressed, sending a new signal that will shut off the water line. It too will then be timed out. 
     In a preferred embodiment, the outer housing  10  is fabricated out of a clear polycarbonate and the inner housing wall out of lightweight plastic tubing. A presently preferred dimension of the outer housing is 6″ to 8″ long and 2″ in diameter. The inner water level sensor has dimensions of 4″ to 6″, with a diameter of approximately 1¾″ to permit its sliding reception within the outer housing. The reference probe shaft  28  of the reference probe  16  preferably projects inwardly a distance of approximately ½″. When so dimensioned, suction cups of diameter 1″ are sufficient to maintain the positioning of the water level controller  121  on the pool wall. 
     A receiving slot  64  having dimensions of 1″ long by ¼″ wide is appropriate for such a construction described above, and electrical contact connectors such as microswitch Model #275-016A manufactured by Radio Shack—Tandy Corporation of Fort Worth, Tex., have proven effective, although other switches would be acceptable. A combined transmitter circuit and receiver unit, such as product number 61-2667A by Radio Shack provides a sender and receiver that are sufficient for most installations. A 12-volt battery, such as Radio Shack battery #23-144 can provide power for such circuit. 
     An actuator valve assembly  98 , such as one having both a solenoid and valve, Model No. L 7010 by J. H. Hardie Irrigation of El Paso, Tex., is presently preferred, although other, analogous units are well known to the art. 
     In certain environments, the contact switches  66   a,    66   b  (FIGS. 5 and 6) can pose problems as electrical contact is made and broken during operation. An alternative design shown in FIG. 10 utilizes sealed switches that are operated by a magnetic field to considerably simplify the operation of the liquid level sensor. An outer casement  150  is provided a magnet  153  that is attached to a first lateral side  154  thereof. A dampening aperture  155  is formed in an upper surface  157  of the outer casement  150 , with an access opening (not shown) provided opposite thereto to enable placement of a sensor circuit housing  161  within the outer casement  150 . 
     A sealed access cover  162  attaches to the sensor circuit housing  161  to create a liquid-tight seal, protecting a sensor circuit  163  that is placed within the sensor circuit housing  161 . Included as part of the sensor circuit  163  is an electrical battery  165  that provides electrical power to actuate the circuit. 
     Included on the sensor circuit  163  is an identical or analogous transmitter unit to that depicted under reference number  36  in FIGS. 5 and 6. The sensor circuit  163  also includes a pair of magnetic reed switches  171 . The interaction between the magnet  153  on the outer casement  150  and the pair of magnetic reed switches  171  is best explained with reference to FIG.  11 . 
     As is well known to the art, the magnetic reed switches  171  consist of a pair of electrical leads  175   a,    175   b  that are brought together within a sealed glass envelope  177 . Turning now to FIG. 11, as the magnet reed switch  171  is brought into the environment of the magnet  153 , the pair of electrical leads  175   a,    175   b  make electrical contact with one another. As the magnetic reed switch  171  is removed from the immediate environment of the magnet  153 , the pair of electrical leads  175   a,    175   b  separate from one another, breaking electrical contact. 
     In operation, as shown in FIG. 12 a liquid level controller  181  is attached to a side of a liquid container, such as the sidewall of the swimming pool  125 . The magnet  153  is attached at a fixed position on the outer casement  150 . The sensor circuit housing  161  (not shown in FIG. 12) floats within the outer casement  150 , with the relative positions of the sensor circuit  163  and the magnet  153  dependant upon the fluctuation of the liquid level within the container. The dampening aperture  155  cooperates with the floating sensor in a manner that dampens movement of the sensor within the outer casement  150 . Such dampening provides a more accurate indication of the liquid level, and permits the sensor to disregard momentary fluctuation in that liquid level. 
     With the outer casement  150  fixedly attached to the sidewall  123 , a lowering of the liquid level results in the sensor circuit  163  moving downward relative to the magnet  153 , bringing an upper one of the magnetic reed switches  171 , causing electrical contact to be established, which in turn results in the transmission of an activation signal to the actuator valve assembly (not shown in FIG.  12 ). As the liquid level rises, for example upon initiation of a filling operation, the upper one of the magnetic reed switches  171  becomes more distant from the magnet  153 , while a lower one of the magnetic reed switches  171  eventually lies adjacent the magnet  153 , resulting in the generation and transmission of yet another signal, again activating the actuator valve, ending the filling operation. 
     My invention has been disclosed in terms of a preferred embodiment thereof, which provides an improved water level controller for swimming pools—or in fact any application where the control of the level of a liquid is important, that is of great novelty and utility. Various changes, modifications, and alterations in the teachings of the present invention may be contemplated by those skilled in the art without departing from the intended spirit and scope thereof. It is intended that the present invention encompass such changes and modifications.