Patent Publication Number: US-2022228354-A1

Title: Toilet overflow prevention system and method

Description:
RELATED APPLICATIONS 
     Related applications are listed on an Application Data Sheet (ADS) filed with this application. The entireties of any applications listed on the accompanying ADS are hereby incorporated by reference herein and made a part of this specification. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention generally relates to toilets. More specifically, the present invention relates to an overflow prevention device for a toilet. 
     Description of the Related Art 
     Although significant advances have been made in toilet technology, particularly in reducing the amount of water needed for flushing purposes, a satisfactory solution for preventing the overflow of a toilet in the event of a blockage of the toilet bowl, or associated waste plumbing, has not been achieved. Existing overflow prevention devices, in order to provide acceptable reliability, are often complex and result in the devices having a high cost. Furthermore, existing overflow prevention devices often include visible components, which can result in a displeasing appearance. 
     SUMMARY OF THE INVENTION 
     Preferred embodiments of the present invention operate to prevent toilet overflow in a cost-effective and reliable manner. In addition, preferred embodiments may be integrated into a toilet assembly during manufacture or retrofitted into an existing toilet, preferably with little or no modification of the standard toilet. Embodiments intended for retrofitting in existing toilets desirably require a low level of skill to install. 
     An aspect of the present invention involves a toilet overflow prevention system for use with a toilet, including a sensor capable of detecting vibration of the toilet during a flush cycle. The sensor generates a signal indicative of the vibration. A processor receives the signal from the sensor and processes the signal to determine if the vibration is indicative of an impeded flush condition. If an impeded flush condition is determined to exist, the processor generates a control signal. An actuator receives the control signal from the sensor and in response to the control signal operates to close a valve, which stops a flow of water within the toilet. The valve may be the flapper valve of the toilet that controls a flow of water from the tank to the bowl of the toilet. 
     Another aspect of the present invention involves a method for preventing toilet overflow, including detecting a vibration of the toilet during a flush cycle and comparing a parameter of the vibration to a normal range of the parameter. The method also includes determining that an impeded flush condition exists if the parameter is outside of the normal range and closing a valve to at least substantially stop a flow of water within the toilet. 
     Still another aspect of the present invention involves a method of calibrating a system for detecting an impeded flush of a toilet comprising sensing the value of a parameter of one or more normal flush cycles of the toilet and establishing a normal range for the value of the parameter using the sensed value. The method may also include storing the normal range in a memory for comparison to a value of the parameter during subsequent flush cycles. The method may further include the sensing being performed over a predetermined timeframe. The method may still further include the time frame being sufficient to include the entire push cycle of the toilet. 
     Another aspect of the present invention involves a method of determining the existence of an impeded flow condition of a toilet comprising sensing a value of a parameter of a flush cycle caused by water dynamics within the toilet, comparing the sensed value of the parameter to a normal range of values for the parameter and determining that an impeded flow condition exists if the sensed value is outside of the normal range. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects, and advantages of the present invention are described in connection with preferred embodiments of the invention, in reference to the accompanying drawings. The illustrated embodiments, however, are merely exemplary and are not intended to limit the invention. The drawings include the following nine figures. 
         FIG. 1  is a side, partial cross-sectional view of a toilet incorporating an overflow prevention device including certain features, aspects and advantages of the present invention. The toilet generally includes a base, defining a bowl, and a tank supported on the base. An interior of the tank communicates with the bowl through a passage. 
         FIG. 2  is a schematic illustration of the toilet and the overflow device of  FIG. 1 . The illustrated overflow device generally includes a sensor, a processor, and an actuator. 
         FIG. 3A  is a representation of a sensor output as a function of time in the event of a normal flush condition. 
         FIG. 3B  is a representation of a sensor output as a function of time in the event of an impeded flush condition. 
         FIG. 4  is a flow chart of a control method for a toilet overflow prevention system. 
         FIG. 5  is a flow chart of a control method for determining if an impeded flow condition is present in the bowl of a toilet. 
         FIG. 6  is a flow chart of a toilet overflow prevention device calibration method. 
         FIG. 7  is a perspective view of an embodiment of an actuator of the toilet overflow prevention device of  FIG. 1  and  FIG. 2 . The actuator of  FIG. 7  is configured to shut the flapper valve of a toilet in response to an appropriate control signal. 
         FIG. 8  is a perspective view of the actuator of  FIG. 7  attached to a toilet overflow tube. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  illustrates a preferred embodiment of a toilet overflow prevention system  10  incorporated within a toilet  12 . The system  10  detects when waste water is not properly emptying from the toilet, generally referred to herein as an impeded flush condition. The detection of an impeded flush condition advantageously occurs during a flush cycle, such that remedial action can be taken by the system  10  during the same flush cycle. The system  10  is capable of stopping a flow of water within the toilet  12  to prevent an overflow situation in response to the detection of an impeded flush condition. Preferred embodiments of the system  10  detect a measurable characteristic or parameter caused by the effects of fluid dynamics during the flush cycle, such as vibration, sound, fluid flow rate or pressure, and determine if an impeded flush condition exists based on the measured characteristic or parameter. 
     The toilet  12  preferably is of a conventional configuration and includes a base  14  and a tank  16  supported on the base  14 . Although the overflow prevention system  10  is described herein in the context of such a toilet  12  having a base  14  and a tank  16 , the system  10  may be adapted for use with toilets having alternative configurations, such as a monolithic construction, as will be appreciated by one of skill in the art in view of the present disclosure. 
     The base  14  defines a bowl  18 , which is configured to hold a volume of water  20 . A siphon tube  22  connects the bowl  18  with a wastewater plumbing system  24 . The siphon tube  22  extends in an upward direction from a lower portion of the bowl  18  and then curves into a downward direction toward the lower end of the base  14  to meet the wastewater plumbing system  24 . Accordingly, the height of the upper curve  14   a  determines a normal water level W N  within the bowl  18 . 
     Preferably, the tank  16  is of a hollow construction and defines an interior space configured to hold a volume of water  20 . The volume of water  20  in the tank  16  preferably defines a normal water level W T . Thus, the interior of the tank  16  is the divided into a water portion P W  and an air portion P A . Preferably, an open upper end of the tank  16  is covered by a lid  28 . 
     Water  20  is evacuated from the tank  16  through an outlet  30  defined within a lower wall of the tank  16 . Water  20  that passes through the outlet  30  is delivered to the bowl  18  to initiate a flushing action. For example, in a washout-type toilet, water  20  from the tank  16  is delivered to the bowl  18  through a passage  32  and gallery  34 , as shown. The passage  32  extends generally vertically from the tank outlet  30  to the gallery  34 . The gallery  34  is oriented in a horizontal plane and, preferably, substantially surrounds the bowl  18  at its upper edge, or rim. Openings  36  permit water  20  to flow from the gallery  34  into the bowl  18 . However, it will be appreciated by those of skill in the art that the present system  10  may be used with any type of toilet, including siphon jet-type and blowout-type toilets, for example. 
     With additional reference to  FIG. 1 , the toilet  12  includes a primary flush valve, or flapper valve  38 . The illustrated flapper valve  38  pivots between a closed position, wherein water  20  within the tank  16  is substantially prevented from flowing through the tank outlet  30 , to an open position, wherein the water  20  within the tank  16  is permitted to flow through the tank outlet  30  and into the bowl  18  through the passage  32  and the openings  36  of the gallery  34 . The flapper valve  38  is coupled to a handle  40  external to the tank  16 , which permits a user to activate flushing of the toilet  12  by utilizing the handle  40  to move the flapper valve  38  to the open position. The flapper valve  38  is configured to close automatically once the water  20  within the tank  16  is reduced to a particular level. 
     With continued reference to  FIG. 1  and  FIG. 2 , the toilet  12  also includes a tank fill mechanism  42  configured to refill the tank  16  with water  20  from an external water supply source  44  after the tank  16  has been emptied, or the volume of water  20  reduced, during a flush cycle. The tank fill mechanism  42  includes a filler valve  46 , which is typically supported at a height above the lower end of the tank  16  by a support structure  48 . The filler valve  46  is configured to selectively permit water  20  from the water supply  44  to fill the tank  16  and, typically, the bowl  18 . 
     The filler valve  46  supplies water  20  to the tank  16  and the bowl  18  through a supply line  50 . Preferably, the supply line  50  includes a first branch, or tank supply branch  52  and a second branch, or bowl supply branch  54 . The tank supply branch  52  supplies water  20  directly into the interior of the tank  16 . 
     The bowl supply branch  54  supplies water  20  to the bowl  18  through an overflow tube  56 . The overflow tube  56  includes an open upper end  58  and a lower end  60 , which defines a discharge opening  62 . The bowl supply branch  54  supplies water  20  to an internal passage of the overflow tube  56  through the upper end  58  and water is discharged through the discharge opening  62 . 
     Preferably, the upper end  58  of the overflow tube  56  is positioned above a normal water level W T  within the tank  16 . The discharge opening  62  preferably is positioned below the flapper valve  38  to permit water  20  within the tank to move into the bowl  18  through the overflow tube  56  when the flapper valve  38  is in a closed position. Thus, the overflow tube  56  permits water  20  above a normal water level W T  to bypass the flapper valve  38  in the event that the water level within the tank  16  rises above the upper end  58  of the overflow tube  56 , for example, in the event of a malfunction of the filler valve  46 . The overflow tube  56  also permits the filler valve  46  to supply water  20  to the bowl  18  through the discharge opening  62  when the flapper valve  38  is in a closed position. 
     The filler valve  46 , in the illustrated arrangement, is controlled by a tank water level sensor in the form of a float  64 . Thus, the float  64  establishes the normal water level W T  within the tank  16  by moving the filler valve  46  to a closed position upon reaching a desired water level W T . 
     With continued reference to  FIGS. 1 and 2 , the procedure of flushing the toilet  12  generally comprises a flush cycle. The flush cycle can be considered to include a push cycle and a refill cycle. During the flush cycle the contents of the toilet bowl  18  are removed through the siphon tube  22  by water  20  being passed from the tank  16  and entering the bowl  18 . In some embodiments, the flush cycle is initiated by actuating the lever  40  that opens the flapper valve  38  thus releasing water from the tank  16  to bowl  18 . The initial part of the flush cycle in which the flapper valve  38  has been actuated by the lever  40  and is held open by the buoyancy of the flapper valve  38  and movement of water  20  through the passage  32 , is generally referred to as the push cycle. During the push cycle a portion, and usually a substantial amount, of the water  20  in the tank  16  is passed from the tank  16 , through the passage  32  and the gallery  34  and into the bowl  18 . Thus, during the push cycle a substantial amount of water  20  typically is passed from the tank  16  into the bowl  18 . During a normal push cycle, the rapid increase in water level in the bowl  18  preferably creates a siphon effect that removes the contents of the bowl  18  to the wastewater system  24  through the siphon tube  22 . 
     During the flush cycle, the push cycle preferably transitions to a refill cycle in which the flapper valve  38  closes and substantially reduces the flow of water  20  from the tank  16  to bowl  18  through the passage  32 . During a refill cycle the tank fill mechanism  42  refills the tank  16  and also refills the bowl  18  via the supply line  50  that includes a branch  54  that feeds water to the overflow tube  56  and subsequently into the bowl  18 . Once the water level in the tank  16  has returned to a normal level W T , as shown in  FIG. 1 , the float  64  shuts off the filler valve  46  to end the refill cycle and thus end the flush cycle. 
     During the flush cycle, and particularly during the push cycle, the body of the toilet  12  is affected by the fluid dynamics caused by fluid moving within the toilet  12 . It has been discovered by the present inventors that the fluid dynamics produce a number of measurable characteristics or parameters that can be used to detect if the flush cycle is normal. That is, by measuring the characteristics or parameters produced by the fluid dynamics during the flush cycle, it is possible to determine if the toilet  12  is in an impeded flush condition or if the toilet  12  is in a normal flush condition. 
     Generally, an impeded flush is considered as any flush cycle in which a blockage or flow restriction causes a significant reduction in the normal flow of contents from the bowl  18  to the wastewater plumbing system  24 . Advantageously, certain embodiments of the present system  10  can be adapted to respond to different levels of restriction to flow by, for example, correlating the level of the sensed characteristic or parameter with the level of the flow restriction. The impedance can comprise content that is clogged within the siphon tube  22  or some kind of backup or clogging in or related to the wastewater plumbing system  24 . As will be appreciated by one skilled in the art, an impeded flow can be caused by a wide variety of factors all of which cannot be predicted. 
     In some embodiments, a normal flush is generally considered a flush cycle in which the contents of the bowl  18  can relatively freely flow out of the bowl  18  through the siphon tube  22  and into the wastewater plumbing system  24  without substantial blockage or reduction of flow. Typically, under normal flush conditions, repeated flush cycles will not cause the water level in the bowl  18  to rise above, or remain above, the normal water level. 
     With continued reference to  FIG. 1  and  FIG. 2 , one embodiment of a toilet overflow prevention system  10  includes a sensor  70  that is configured to sense a parameter of the flush cycle. The sensor  70  is in communication with an actuator  72  that is capable of initiating or implementing a substantial or total reduction in the amount of water  20  that can flow to the bowl  18  of the toilet  12 . In some embodiments, the sensor  70  sends a control signal to a processor  78  to be processed by the processor  78 , which then transmits a control signal to the actuator  72 . The processor  78  includes a suitable algorithm that is configured to determine if the signal is indicative of certain flow conditions and also can include algorithms that decide if action should be taken in response to the signals. The processor  78  can also include various algorithms for calibrating the toilet overflow prevention system  10 , which will be discussed in greater detail below. 
     The sensor  70 , the processor  78  and the actuator  72  may be in communication with one another by various different means. Such suitable means may include a hardwired cable or a wireless signal, such as an RF signal or an acoustic signal. Other suitable methods for communication between the sensor  70 , actuator  72  and processor  78 , as well as any other components of the system  10 , may also be employed. Although illustrated as separate components in  FIGS. 1 and 2 , the sensor  70  and actuator  72  could be part of an integrated assembly, in which communication between the sensor  70  and actuator  72  could be integrated such that a separate wired or wireless communication link is not necessary. Accordingly, as discussed further below, the sensor  70  is not limited to the location (e.g., outside of the tank  16 ) shown in  FIGS. 1 and 2 , but may be positioned in any suitable location in which the desired flush characteristic or parameter may be adequately sensed. Thus, in some arrangements of the system  10 , the sensor  70  may be positioned within the tank  16 . 
     The sensor  70  preferably includes necessary components to sense a desired parameter, create a signal indicative of the parameter that can be communicated to other portions of the system  10 . The illustrated sensor  70  includes a sensing element  74  that is configured to detect a desired parameter of a flush cycle of the toilet  12 . The sensing element  74  may be any suitable type of transducer that is capable of converting a physical measurement into an electronic signal. Such a suitable transducer can comprise vibrating elements (e.g., accelerometers), optical measurement elements, deflecting elements, capacitive, inductive, electromagnetic, strain gauge, piezoelectric, acoustical elements, etc., as will be appreciated by those of skill in the art. In some embodiments, the sensor  70  may include or communicate with a transmitter  76  that is configured to transmit a signal to a processor  78 , or another portion of the system  10 . In some embodiments, the sensing element  74  and/or transmitter  76  may be separate components from the sensor  70  or may be integrated with the sensor  70 . Also, as will be appreciated by one skilled in the art, in certain configurations of the toilet overflow prevention system  10 , the transmitter  76  may not be required. 
     In some embodiments, the system  10  or processor  78  may include a memory  80  for storing certain protocols or parameters that may be used in the processing of signals from the sensor  70 . The protocols or parameters may be preprogrammed or they may be established during a calibration process that is described in greater detail below. 
     The toilet overflow prevention system  10  also preferably includes an actuator  72  that, in some embodiments, may comprise a receiver  82  that is configured to receive a signal from the sensor  70  that has been processed by the processor  78 . The actuator  72  may also comprise an electromechanical device  84  that, in some embodiments, is arranged to close the flapper valve  38  of the toilet  12 . One exemplary embodiment of the actuator  72  is discussed in greater detail below with reference to  FIG. 7  and  FIG. 8 . 
     As discussed above, the sensor  70  can comprise various different types of sensors to detect various parameters of a flush cycle of the toilet  12 . Moreover, it may be desirable to utilize multiple sensors to provide additional information to the system  10 , such as a confirmation of an impeded flush condition to reduce the possibility of a false determination of an impeded condition, which could possibly occur in certain circumstances using only a single sensor or single sensor type. In one embodiment, the sensor  70  detects vibrations of the toilet  12  during a flush cycle. Such a detection of vibrations may comprise directly detecting vibrations of the toilet  12  or indirectly detecting vibrations of the toilet  12 . On example of indirect detection of toilet vibration is to detect acoustical vibrations that are produced by the toilet  12  during a flush cycle. On example of direct detection can comprise detecting the physical displacement of the toilet  12  during a flush cycle, such as with accelerometers, strain gages, or other suitable sensors. 
     In one embodiment, the sensor  70  is an accelerometer that contacts the toilet  12 . In one preferred arrangement, the sensor  70  is coupled to the bolt  17  connecting the tank  16  to the bowl  18  as shown in  FIG. 1 . Such a placement is suitable for detecting vibrations and is also relatively inconspicuous. However, other suitable placements of the sensor  70  are also possible, such as when the system  10  is used with a monolithic toilet model in which the bowl and tank are formed as a single piece. 
     During the push cycle of a flush cycle, when the flapper valve  38  is open and water is permitted to move from the tank  16  to the bowl  18  through the passage  32 , there are detectable parameters that can indicate an impeded flush. For example, if the siphon tube  22  were to have some type of the impedance wherein the water  20  could not flow out of the bowl  18 , when the water  20  begins to pass from the tank  16  to the bowl  18 , the water  20  in the bowl  18  will begin to rise thus providing a larger than normal amount of water  20  in the bowl  18 . In addition, the water  20  may flow at a slower rate than normal from the tank  16  to the bowl  18 , thus resulting in a slower rate of change of the water level in the tank  16 , which could be measured. Similarly, the rate of change of the pressure within the tank  16 , or pressure differentials within the toilet  12  (e.g., between the tank  16  and the bowl  18 ), may vary in an impeded flush condition from the values typical of a normal flush condition. These differences as compared to a normal flush cycle have been discovered by the present inventors to affect certain parameters or characteristics of the toilet  12 , including the vibrational characteristics of the toilet  12 . In such circumstances, the amplitude of the vibration of the toilet  12  is decreased, possibly due to the increased amount of water  20  in the bowl  18 , the decreased flow rate of the water from the tank  16  to the bowl  18 , among other possibilities. It is possible that the decrease in amplitude is, in part, due to the damping effect of the larger-than-normal volume of water  20  in the bowl  18  in the event of an impeded condition. The above-described example is with reference to an accelerometer that can measure amplitude of vibration. As will be appreciated by one skilled in the art, other parameters that can be detected may include frequency or other vibrational parameters that may be measured in the frequency and/or time domains. Such alternative parameters can also be used to determine if an impeded flush condition exists. 
     One example of a vibrational signal  100  that is produced by a sensor, such as the sensor  70 , during a flush cycle is illustrated in  FIG. 3A  and  FIG. 3B . The vibrational signal  100  shown in  FIG. 3A  and  FIG. 3B  is an amplitude versus time plot wherein the amplitude of the vibrational signal  100  oscillates over a period of time. In the particular illustrated embodiment, the time period over which the vibrational signal  100  is displayed is approximately 8 seconds, which is a sufficient period of time to capture a typical push cycle portion of a toilet flush cycle. Experimentation has shown that a typical push cycle is about 6 seconds for toilets that are currently available for consumer use. However, it will be understood that the push cycle time may be considerably longer, depending on the toilet type, especially older toilets that use, for example, 3-5 gallons of water per flush. Although such toilets are not currently produced, at least in significant volumes in the United States, the present system  10  may be used with, or adapted for use with, such toilets. Thus, the illustrated vibrational signal  100  is an example of the typical vibrational signal over the entirety of the push cycle of a flush cycle for toilets that have a push cycle of less than about 8 seconds. However, the system  10  may also be adapted for a desired time interval to correspond to a desired sensing duration. Accordingly, the system  10  can be adapted for the timing of a particular flush cycle. For example, because it is possible to accurately determine the existence of an impeded flush condition in significantly less time than a complete push cycle, some embodiments of the system or method may utilize only a portion of the push cycle. 
       FIG. 3A  illustrates a normal push cycle wherein the vibrational signal  100 , at least during a push cycle, maintains substantially the same amplitude at each vibrational peak, or for each period.  FIG. 3B  illustrates a vibrational signal  100  of an impeded flush condition in which the peak amplitude of the vibrational signal  100  decreases over time. The graphs of  FIGS. 3A and 3B  illustrate that, during a push cycle, the peak amplitude is a parameter of the vibration of the toilet  12  that is capable of being monitored to distinguish between an impeded flush and a normal flush. Thus, the vibrational signal  100  can be used to determine if the actuator  72  should be actuated in response to any particular flush cycle. In light of the present disclosure, it is apparent that multiple parameters may be satisfactory for use in distinguishing between a normal flush condition and an impeded flush condition in addition to the peak amplitude of the vibrational signal  100  specifically illustrated in  FIGS. 3A and 3B . Some of the other possible determination criteria are discussed in greater detail below. 
     In another embodiment the sensor  70  can comprise an acoustic sensor that, in some embodiments, may be placed on or adjacent to the toilet  12 . As will be appreciated by one skilled in the art, the vibrations that can be detected by an accelerometer will, in some embodiments, also create an acoustic signal that can be measured with a transducer, such as a microphone, much like the accelerometer measures vibration of the toilet  12 . Once again, in some embodiments, amplitude of the acoustic signal can be measured to determine if an impeded flow condition exists. Detecting acoustical vibrations can be particularly advantageous in that the sensor  70  can be placed in various different locations that are in audible communication with the toilet  12 . This can provide a wider range of sensing positions as compared to the vibrational sensing described above with reference to a vibration sensor, such as an accelerometer. 
     In another embodiment, the sensor  70  can comprise a flow rate sensor that can measure certain flow parameters in the toilet  12  during a flush cycle. One example of a flow rate sensor that can be used to determine a parameter of a flush cycle is a flow rate sensor that monitors flow through the siphon tube  22  of the toilet  12 . For example, if there is a blockage in the siphon tube  22 , the flow rate of fluid within the toilet  12 , such as the flow rate through the siphon tube  22  or through the passage  32  between the tank  16  and the bowl  18 , is measurably reduced in most toilets, thus indicating an impeded flow condition. Similar to the vibrational sensing method described above, the flow rate can be measured during a push cycle so that there is sufficient time to close the flapper valve  38  and stop the push cycle prior to contents overflowing from the bowl  18 . 
     In a similar variation of the system  10 , an impeded flush condition may be determined by measuring and analyzing a water level within the toilet  12  and, in one arrangement, a change in the level of the water  20  in the tank  12  over time. In other words, the rate of the level change of the water  20  in the tank  12  (e.g. water level drop) can be measured and the measured values used to determine if an impeded flush condition exists. It is expected that the rate of water level change within the tank  12  will be slower than normal if an impeded flush condition exists. The rate of change of the water level may be measured by any suitable sensor, such as a mechanical sensor (e.g. float), for example. Other types of sensors may be used as well. Such an arrangement has an advantage that the water level rate of change may be more practical to measure than the water flow rate (described above) or pressure (described below). 
     In another embodiment, the sensor  70  can comprise a pressure sensor that, similar to the sensor embodiments described above, can measure certain parameters of a flush cycle that may be indicative of an impeded flush condition. One example of a usage of a pressure sensor is to place a pressure sensor within the toilet  12 , such as in the tank  16 , bowl  18  or passage  32  therebetween, to measure a pressure characteristic of a fluid within the toilet  12  (e.g., water  20  or air). In such a configuration, in an impeded condition, the water  20  in the tank  16  may drain at a slower rate than that of a normal flush, thus crating a greater head pressure for a longer period of time in the tank  16 . As will be appreciated by one skilled in the art, a pressure sensor can be used in a variety of different capacities to detect an impeded flush. For example, it may be desirable to measure pressure differentials at two locations within the toilet  12 , and base the decision-making of the system  10  on a pressure differential, rather than on an absolute pressure value. 
     As discussed briefly above, the sensor  70 , in many of its possible embodiments, can be used to detect a parameter of a flush cycle that is indicative of an impeded flush. In some embodiments, the determination of whether the detected parameter is indicative of an impeded flush or a normal flush is achieved by the processing of information gathered by the sensor  70 . For example, the signal produced by the sensor  70  may be processed by the processor  78  utilizing one or more algorithms that compare the sensed value of a parameter, or parameters, to the known or expected value of the parameter(s) that are known to be indicative of an impeded flush and/or known to be indicative of a normal flush. That is, the data gathered by the sensor  70  preferably is used to determine if the flush cycle is impeded.  FIG. 3A  and  FIG. 3B  illustrate how, in one embodiment, the condition of the flush cycle can be determined as a result of sensed vibrations of the toilet  12 . 
     As discussed above,  FIG. 3A  is a representation of a vibrational signal  100  from the sensor  70 . The vibrational signal  100  is plotted on an amplitude versus time plot such that time is plotted on the x-axis and the amplitude of the vibration is plotted on the y-axis. Also plotted in  FIG. 3A  are an average peak value  104  and a threshold value  106 . In the illustrated embodiment, the average peak value  104  is an average line of the peak values P 1 -P 7  of the vibrational signal  100 . The threshold value  106  is an established value that can be compared to the average peak value  104  such that when the average peak value  104  drops below the threshold value  106  an impeded flush is determined to be present. The threshold value  106  can be established through various methods including through experimentation or through a calibration procedure, which is described in greater detail below. 
       FIG. 3A  illustrates a normal flush in which the average peak value  104  does not drop below the threshold value  106  during the particular time interval of interest, which in some arrangements may include the entire push cycle. In contrast,  FIG. 3B  illustrates an impeded flush in which the average peak value  104 ′ drops below the threshold value  106 ′ in the plotted time interval. Thus, as shown in  FIG. 3B  the vibrational signal  100 ′ comprises peak values P 1 ′-P 7 ′ in which the latter peak values P 5 ′-P 7 ′ are below the threshold value  106 ′. That is, the average peak value  104 ′ that establishes a trend line for the peak values P 1 ′-P 7 ′ drops below the threshold value  106 ′ thus indicating that an impeded flush condition exists. In other arrangements, the system  10  may look only at the individual peak values, rather than an average of the peak values and determine that an impeded condition exists if any of the peak values drops below the threshold value  106 ′. 
     Although the vibrational signal  100  and  100 ′ illustrated on  FIGS. 3A and 3B  is illustrated showing peak values P 1 -P 7  and P 1 ′-P 7 ′, it will be appreciated by one skilled in the art, that various numbers of peak vales may exist for different vibrational signals. The illustrated vibrational signals  100  and  100 ′ are simply examples and are not intended to limit the scope of the present invention. Furthermore, due to the variation of water dynamics in a toilet during different flush cycles, it is possible that no two vibrational signals will be identical, although it has been determined by the present inventors that the vibrational signals for a particular toilet are consistent enough to permit the accurate distinction between a normal and impeded flush condition. 
     With continued reference to  FIG. 3A  and  FIG. 3B , the time interval shown in the plots, in some embodiments, can be predetermined so as to capture an appropriate timeframe to measure the vibrational signal of a push cycle of a flush cycle. In the particular illustrated embodiment, the timeframe is approximately 8 seconds, which generally can encompass an entire push cycle of a flush cycle. In many toilets, a push cycle will take approximately 6 seconds, thus a timeframe of eight seconds, in many embodiments, is sufficient to view the entire push cycle. As will be appreciated by one skilled in the art, other timeframes or time windows may be used, as described above, particularly in connection with toilets that have a push cycle time significantly longer than about 6 seconds. 
     Although the particular illustrated vibrational output shown in  FIG. 3A  has been illustrated wherein each of the peaks P 1 -P 7  have been illustrated as being above the threshold value  106 , in other embodiments, some of the peak values of the vibrational signal  100  may fall below a threshold value  106  but may not indicate an impeded flush. That is, in some impeded flush determination methods, the peak values P 1 -P 7  of the vibrational signal  100  may be allowed to fall below the threshold value  106  for a certain period of time. This can be achieved by an algorithm that determines how many peak values have fallen below a threshold value in a certain amount of time. This can be particularly advantageous when a vibrational signal may produce some sporadic or outlying peaks that may fall below a threshold value but may not necessarily indicate an impeded flush condition. Thus, by providing a time constraint that requires the peak values P 1 -P 7  (or average of the peak values  104  and  104 ′) to fall below the threshold value  106  for a certain amount of time (e.g., the period T in  FIG. 3B ), the likelihood of an incorrect determination of an impeded flush condition may be reduced. In other words, an algorithm may be used that requires the peak values P 1 -P 7  to drop below the threshold vale  106  for a particular period of time T before an impeded flush is determined to be present. Other arrangements may determine that an impeded condition exists if a particular number of consecutive peak values fall below the threshold value  106 . Other possibilities for determining that an impeded condition exists from a sensed signal will be apparent to those of skill in the art in view of the present disclosure. 
     Although the illustrated example of  FIGS. 3A and 3B  involves determining the existence of an impeded flush condition by analyzing peak values of a sensed vibration in comparison with a minimum threshold value, other algorithms may be used to analyze the sensed vibration and, more particularly, the output signal of the sensor  70 . These algorithms may also be applied to any other sensed parameter or sensor output signal, regardless of type. For example, a frequency domain-type algorithm may be used to analyze the sensor output including, without limitation, an FFT (Fast Fourier Transform), DCT (Discrete Cosine Transform), an others. Time domain-type algorithms may be used, including, without limitation, integral (e.g., integration of a real time signal), derivative (rate of change), running window, envelope detectors, various types of filters (e.g., low, band or high pass), adaptive filters, etc. Moreover, combinations of time and frequency domain processing may be used, as taught by modern digital signal processing methodologies, as will be apparent to those of skill in the art. 
     In some embodiments, the toilet overflow prevention system  10  can be calibrated for a particular toilet on which it has been installed. This calibration can establish a threshold value that can be substantially similar to the threshold value  106  and  106 ′ described above, to be used to determine the condition of a flush cycle. In the illustrated embodiment, the toilet overflow prevention system  10  can be calibrated on a particular toilet such as the toilet  12  of  FIG. 1  with one or more known normal flush cycles that can establish the threshold value  106  or  106 ′ to which future flush cycles can be compared. 
     In one embodiment, after the toilet overflow prevention system  10  has been installed on a particular toilet, one method to calibrate the system  10  can comprise the user activating a calibration mode of the toilet overflow prevention system  10  such that the system  10  is alerted that the flush or flushes that are soon to follow are calibration flushes. One arrangement enters a calibration mode immediately upon first being turned on. During the calibration, a user preferably activates one or more flushes that are known normal flushes. For example, the user preferably visually verifies that the calibration flushes are normal, or unimpeded. That is, the user can simply flush the toilet at a time when it is known that no impedance will occur. During the normal flushes, the processor  78  receives the output of the sensor  70  that, in some embodiments, may produce an output similar to the signal  100  shown in  FIG. 3A . In one embodiment, an algorithm can be applied such that a threshold value or range is determined from the peaks P 1 -P 7 . That is, an algorithm can be used to establish the threshold value  106  from the peak values P 1 -P 7  such that the threshold value  106  is set at a predetermined or calculated amount below the peak values P 1 -P 7 . After the establishment of the threshold value  106 , the threshold value  106  can be stored in a non-volatile memory (e.g., memory  80 ) and used to compare to future flush cycles to detect an impeded flush condition. 
     As will be appreciated by one skilled in the art, various different algorithms can be used to establish or calculate a threshold value that then distinguishes between a normal and an impeded flush for a particular parameter. As noted above, certain other conditions may be required to be present in order to determine that an impeded flush condition exists, such as the values being below (or above) the threshold value for a period of time or for a certain number of consecutive values. In addition to the algorithm described above, an alternate algorithm may produce a range or envelope, having upper and lower limits, about a certain measured parameter so as to establish a normal operating range that can be compared to future flushes to determine if an impeded flush condition exists. 
     One particular advantage provided by calibrating the overflow prevention system  10  after it has been installed on a particular toilet is that many of the operating parameters, including acoustic and vibrational signatures produced by a particular toilet, may be sensitive to the surrounding environmental conditions. For example, a toilet installed on a concrete floor may produce a different vibrational signature than a toilet installed on a wood floor. Also, for example, a toilet installed in a large spacious room may have a different acoustic signature than a toilet installed in a small room or water closet. Thus, calibrating the toilet overflow prevention system  10  after it has been installed in its operational location can provide a more accurate baseline for determining if a flush cycle is impeded. 
     As discussed above, however, the calibration of the toilet overflow prevention device can also be performed prior to installation. In some embodiments, tests can be performed to establish a set of predetermined ranges or values for a particular toilet or style of toilet such that the calibration procedure described above is not required. For example, if a group of toilets is to be installed under similar operating conditions, the range of threshold values to determine if a flush cycle is impeded can be predetermined and preprogrammed so that the toilet overflow prevention devices need not be calibrated after installation. Such a system may be pre-installed as a part of the original toilet, for example. 
       FIGS. 4-6  are flow diagrams that illustrate preferred control methods that may be employed with some of the foregoing embodiments. In  FIG. 4 , a control method is provided for toilet overflow prevention. At block  120 , a flush cycle signature is detected that is produced by a parameter of a flush cycle of a toilet. As described above, this can be achieved in a variety of different ways including sensing vibration, an acoustic signal, a flow rate, flow level, or a pressure condition. At block  122  the flush cycle signature is determined to be indicative of an impeded flush condition. As described above, this determination can be achieved by an algorithm that, in some embodiment, may be executed in a processor such as the processor  78  of  FIG. 2 . At block  124 , an activation signal is sent to an actuator in response to the impeded flush condition, wherein the actuator is able to implement or initiate a substantial reduction of flow of water to the toilet bowl. As described above, the actuator  72  is configured to receive a signal in response to a detected impeded flush condition. As is discussed in greater detail below, one embodiment of such an actuator is described with reference to  FIG. 7  and  FIG. 8 . 
       FIG. 5  illustrates a method for determining that an impeded flow condition is present. At block  126 , a parameter that is caused by water dynamics within the toilet is sensed. As described above, the parameter can be sensed in a variety of different ways including sensing vibration, an acoustic signal, a flow rate, or a pressure condition. The water dynamics produce detectable parameters that can be analyzed to determine the existence of an impeded flow condition. At block  128 , a parameter value of the water dynamics is compared to a normal range of the parameter value. As described above, the normal range can be determined through a variety of different ways, including through characteristics of the toilet or through a calibration procedure. At block  130 , it is determined that an impeded flow condition exists if the parameter value is outside the normal range. As described above, the determination can be performed by an algorithm in the processor  78 . 
     In  FIG. 6 , a preferred method for calibrating a toilet overflow prevention device is illustrated. At block  132 , a parameter is sensed for one or more known flush cycles of the toilet, wherein the normal flush cycle includes a push cycle. At block  134 , a representative range is established using the parameter that was sensed at block  132 . At block  136 , the range is stored in the memory for later comparative use. 
       FIG. 7  and  FIG. 8  illustrate one embodiment of the actuator  72 . The actuator  72  is generally configured to be attachable to an overflow tube such as the overflow tube  56  illustrated in  FIG. 1 . The actuator  72  preferably is capable of receiving a signal, which is at least in part generated by the sensor  70  and which may be processed by the processor  78 . The actuator is generally configured to forcibly close the flapper valve  38  so as to inhibit or entirely stop the flow of water through the passage  32  from the tank  16  to the bowl  18 . In the particular embodiment illustrated in  FIG. 7  and  FIG. 8 , the actuator  72  is configured to push down the flapper valve  38  via a weight dropping mechanism, which is discussed in greater detail below. 
     The actuator  72  includes a main housing  202  that preferably is a generally tubular member that houses, at least in part, an inner hammer rod  204  and an outer hammer rod  206 . the inner hammer rod  204  and the outer hammer rod  206  are configured to be axially movable within the main housing  202 . The inner hammer rod  204  carries a hammer weight  208  that is attached to the lower end of the inner hammer rod  204 . The main housing  202  also includes an overflow tube attachment structure  210  that allows the actuator  72  to be secured to the top of the overflow tube  56  so as to position the actuator  72  above the flapper valve  38 . 
     With continued reference to  FIG. 7 , the upper portion of the main housing  202  preferably includes a solenoid assembly  212  that is configured to selectively restrain or release the outer hammer rod  206 , which in turn restrains or releases the hammer weight  208 . The solenoid assembly  212 , in some embodiments, comprises a solenoid  214  that is connected to a solenoid latch  216  that defines a mechanical catch to hold or release the outer hammer rod  206 . As discussed briefly above, the solenoid  214  can be actuated by a control signal that may be sent by the sensor  70  or processor  78 . The solenoid  214  may receive a control signal via a hardwired signal or a wireless signal, such as an RF signal, for example. 
     The actuator  72  preferably is configured to hold the hammer weight  208  in an elevated position relative to the flapper valve  38  such that the flapper valve  38  is free to move between its open and closed positions during normal flush cycles. In the illustrated embodiment, after the actuator  72  has received an appropriate control signal, the solenoid  214  activates the solenoid latch  216  to release the outer hammer rod  206 . As a result, the outer hammer rod  206 , and thus the hammer weight  208 , are released and fall downward under their own weight to forcibly close the flapper valve  38 . As discussed above, the detection, processing and release of the hammer rod  206  preferably occurs before the entire flush volume of water is evacuated from the tank  16 . 
     The actuator  72  preferably is configured to have a predetermined amount of stroke for the outer hammer rod  206  relative to the main housing  202 . That is, the outer hammer rod  206  generally determines the amount of movement that the hammer weight  208  will have based on the length of the outer hammer rod  206  and the length of the main housing  202 . In some embodiments, it is preferable that the hammer weight  208  will be lowered to a sufficient height so as to securely close the flapper valve  38 . In the illustrated embodiment, a certain amount of telescopic adjustability is provided between the inner hammer rod  204  and the outer hammer rod  206 . 
     With continued reference to  FIG. 7 , the inner hammer rod  204  preferably is insertable into the outer hammer rod  206  and telescopically adjustable so as to adjust the height of the hammer weight  208  relative to the height of the overflow tube  56 . The inner hammer rod  204  preferably is securable relative to the outer hammer rod  206  by a rod collar  218  that can be tightened to secure the inner hammer rod  204  in a desired position relative the outer hammer rod  206 . 
     Also included in the actuator  72  is a reset latch  220  that is configured to be manually lifted to reset the actuator  72  after the hammer weight  208  has been released by the solenoid latch  216 . As will be appreciated by one skilled in the art, in other embodiments, the actuator  72  can be configured to automatically reset after the hammer weight  208  has been released, thus negating the need for the reset latch  220 . 
     With reference to  FIG. 8 , the actuator  72  is secured to the top of the overflow tube  56  via the overflow tube attachment structure  210 , which is configured to be a snap-fit in the illustrated arrangement. Furthermore, the main housing  202  of the actuator  72  preferably is positioned such that the hammer weight  208  is located generally above the flapper valve  38  such that when the hammer weight  208  is released, it will drop on the top of the flapper valve  38  and forcibly close the flapper valve  38 . 
     With continued reference to  FIG. 8 , the hammer weight  208  is shown being supported in a height set jig  222  which is configured to allow a user to set the height of the hammer weight  208  relative to the outer hammer rod  206  (and the flapper valve  38 ). After the actuator  72  has been installed on the overflow tube  56 , a user preferably loosens the rod collar  218  thus allowing the inner hammer rod  204  to move axially relative to the outer hammer rod  206 . At this time it is preferable that a user place the hammer weight onto the top of the height jig  222  wherein the legs  224  of the height jig  222  are resting on the bottom of the tank  16 . At this time while the hammer weight  208  is being supported by the height jig  222 , a user then preferably tightens the rod collar  218  to secure the inner hammer rod  204  relative to the outer hammer rod  206  thus setting the proper height of the hammer weight  208 . Before the system  10  is placed into use, the height jig  222  preferably is removed. 
     Although one particular embodiment of the actuator  72  has been illustrated with reference to  FIG. 7  and  FIG. 8 , as will be appreciated by one skilled in the art, various other embodiments of actuators can be used to substantially reduce or eliminate water flow to the bowl in  18  in the event of a detected impeded flush condition. Such suitable alternative embodiments may comprise an actuator  72  that independently rests on the bottom of the tank  16  and does not attach to the overflow tube  56 . Other suitable embodiments may comprise an actuator that is attached to the upper rim of the tank  16 . Another suitable embodiment may comprise a rotational solenoid attached to the flapper valve  38  such that a torsional force is applied to the pivoting arm of the flapper valve  38  so as to close the flapper valve in the event of an impeded flush condition. Another embodiment may not comprise an actuator located in the tank  16  but may include an actuator that is attached a valve that controls water flow from the external water supply source  44  as illustrated in  FIG. 2 . Thus, the actuator  72  shown in  FIG. 7  in  FIG. 8  is simply one possible embodiment of an actuator that can be used with the toilet overflow prevention system  10 . 
     Although this invention has been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. In addition, while the number of variations of the invention have been shown and described in detail, other modifications, which are within the scope of this invention, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or subcombinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the invention. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combined with, or substituted for, one another in order to perform varying modes of the disclosed invention. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims.