Patent Publication Number: US-2009224927-A1

Title: Running Water Detection And Alert Device For Plumbing Fixtures

Description:
BACKGROUND 
     1. Field The field is leak detection, in particular detecting and providing an alarm for water running in plumbing fixtures. 
     2. Prior-Art Diffusers and Reflectors 
     The following is a list of some prior art that presently appears relevant: 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                   
                   
                   
                 Patentee or 
               
               
                 Patent or Pub. Nr. 
                 Kind Code 
                 Issue or Pub. Date 
                 Applicant 
               
               
                   
               
             
            
               
                 5655561 
                 B1 
                 1997-08-12 
                 Wendel et al. 
               
               
                 6671893 
                 B1 
                 2004-01-06 
                 Quintana et al. 
               
               
                 6715165 
                 B1 
                 2004-04-06 
                 Schommer 
               
               
                 6877170 
                 B1 
                 2005-04-12 
                 Quintana et al. 
               
               
                 6934977 
                 B1 
                 2005-08-30 
                 Quintana et al. 
               
               
                 2005/0248465 
                 A1 
                 2005-11-10 
                 Flaherty 
               
               
                 2005/0275546 
                 A1 
                 2005-12-15 
                 McKenna et al. 
               
               
                   
               
            
           
         
       
     
     Detection and alarm systems for water leaks are well known. For example, Wendel et al. show a wireless system for detecting and stopping water leaks. A closely-spaced pair of electrically energized electrodes is placed within an area that is likely to accumulate water in the event of a leak. When sufficient current passes between the electrodes and through a detecting circuit, an audible alarm sounds and a radio-frequency transmitting circuit is energized and transmits an alarm signal to a remote receiver circuit. In addition to alarms, provision is made to activate a solenoid valve to stop the flow of water. The complexity of this system will be reflected in its price, which must include proper training for installation and service. A system this complex is non-disposable. 
     Quintana et al. &#39;893 show a system for preventing overflow of a toilet or urinal. A normally-open solenoid valve is inserted between the water supply and the plumbing fixture. One or more water sensors are located near the inside, top edge of the fixture. The sensors are connected to a circuit that controls operation of the solenoid valve. When a drain blockage occurs, water contacts the sensor, sending a signal to the circuit. In turn, the circuit causes the solenoid valve to close, thereby preventing overflow. Audible and visual alarms can be activated when the valve is closed. While this system prevents overflows, it does not solve the problem of a leaky water valve passing water into a toilet or urinal that is not blocked since the sensors will never be contacted by water. 
     Quintana et al. &#39;170 show an elaborate toilet water measuring and flow control system that includes leak and overflow detection and prevention. This system contains many elements. It would not be disposable in the event of failure and it would require a highly-skilled technician for installation and repair. 
     Quintana et al. &#39;977 show a complex, microprocessor-based toilet leak detection and overflow prevention system. As in the case of the above two systems, the complexity of the system causes it to require expert installation and maintenance. It would not be disposable in the event of failure, and it would be expensive. 
     Schommer shows a simple leak detection technique for toilets. A disclosure liquid having high color density is applied around the inner circumference of a toilet bowl, above the resting water line and below the rim drain holes. If a toilet is leaking, water will pass through the drain holes and locally wash away the colored liquid, leaving white streaks. While this system is effective at exposing leaky toilets, it requires application and subsequent evaluation by a user. The disclosure liquid will be removed from the toilet bowl as soon as the toilet is flushed. This limits the long-term utility of this technique. 
     Flaherty shows a leak alarm for toilets and faucets that includes a liquid flow detector and an electronic alarm circuit having two resettable and cooperating timers. A liquid flow detector is inserted in the water supply line for the toilet. Simple logic is employed to observe the operation of the timers and an alarm is sounded when this logic operation detects a leak. As with the previous prior-art designs, this alarm requires installation of a flow detector in the water supply line for the plumbing fixture. 
     A commercial leak detector, model LD-12, manufactured by SubSurface Leak Detection, Inc., of San Jose, Calif., USA, is used industrially to detect leaks in water pipes. A microphone is used to detect sound emanating from a leak. The sound is amplified and filtered to provide a passband of frequencies between 100 and 1,200 Hz. The filtered sound is delivered to earphones worn by an operator. The filter removes or diminishes extraneous sounds from the environment. The optimum filter passband is determined by the type of leak. This instrument is designed for use by skilled personnel. It does not include a timing function to determine the duration of a leak. 
     All of the above prior-art detectors and alarms have one or more of the following disadvantages. All are complex and elaborate and require installation of components either in the vessel, such as the toilet, urinal or toilet tank, or the supply pipe leading to the fixture. Many fixtures, such as sinks and bathtubs, include an overflow drain. If water leaks into the fixture and flows out through the overflow drain, water will be wasted yet no alarm will sound. None is sufficiently simple and inexpensive to be disposable and all require either plumbing or electrical skills, or both, in order to install and maintain them. 
     SUMMARY 
     In accordance with an aspect of one embodiment, an alarm unit comprises a microphone, amplifier, timer, logic circuitry, and audible alarm. The unit is capable of receiving and amplifying sounds of running water in a fixture such as a toilet or sink, and announcing an alarm condition when water is permitted to run for longer than a predetermined time period. In another aspect, the alarm unit further includes a radio transmitter that can relay an alarm condition to a remote receiver, whereupon the receiver can activate an alarm. In another aspect the alarm unit is battery powered or powered by mains. In still another aspect, the unit does not require installation by an expert. In another aspect, the alarm unit is sufficiently simple as to be inexpensive and disposable. 
    
    
     
       DRAWING FIGURES 
         FIGS. 1 through 3  are plan, side elevation, and end elevation views, respectively, of a first embodiment. 
         FIG. 4  is a block diagram of an electronic circuit shown in  FIGS. 1-3 . 
         FIG. 5  shows placement of an embodiment inside or outside a toilet tank. 
         FIG. 6  shows placement of an embodiment outside a sink or urinal. 
         FIG. 7  is a flow chart showing the logical operation of the circuit in  FIG. 4 . 
     
    
    
     DRAWING FIGURE REFERENCE NUMERALS 
     
         
           100  Board 
           105  Microphone 
           110  Circuit 
           115  Alarm 
           120  Battery 
           125  Housing 
           130  Hole 
           135  Grill 
           140  Lamp 
           145  Alarm 
           150  Power supply 
           155  Cord 
           200  Strip 
           400  Amplifier 
           405  Filter 
           410  Detector 
           415  Integrator 
           420  Discriminator 
           425  Logic 
           430  Timer 
           435  Timer 
           440  Timer 
           500  Wall 
           505  Connection 
           600  Sink or urinal 
           605  Water supply line 
           700 - 755  Blocks 
       
    
     FIRST EMBODIMENT 
     Description 
     FIGS.  1  Through  4   
       FIG. 1  shows a top view of one aspect of a first embodiment of a water leak detection and alarm unit. Such a unit detects water leaks that might go unnoticed, either because of absence of persons from a structure, or because the leak occurs in a fixture that has a water-overflow drain, such as a sink or toilet. In the first case, flooding of the structure can occur. In the second case, wastage of water occurs because after it is delivered from the water supply line, it passes through the fixture and into the sewer without serving a useful purpose. 
     An electronic circuit board  100  contains a microphone  105 , a battery  120 , an alarm  115 , and detection circuitry  110 , comprising an amplifier  400 , filter  405 , signal detector  410 , optional integrator  415 , and discriminator  420 . Board  100  also contains logic circuitry  425  connected to detection circuitry  110  and incorporating timers  430 ,  435 , and  440 . Board  100  and associated components are housed in a case or housing  125 . A hole  130  enables sound from outside housing  125  to reach microphone  105 . Similarly, a grill  135  permits sound from alarm  115  to radiate outside case  125 . An optional lamp, such as a light-emitting diode (LED)  140 , is arranged to shine outside case  125  to provide a visible alarm. 
     The openings (hole  130  and grill  135 ) can optionally be covered by a thin, sonolucent membrane to prevent water from entering housing  125 . 
     An optional external alarm  145  can be provided to furnish a remote indication of a leak, if desired. An optional power supply  150  is connected to circuit board  100  by a cord  155  to deliver power to circuitry  110 , in lieu of power supplied by battery  120 . Alternatively, supply  150  can provide current to charge battery  120 . 
       FIGS. 2 and 3  show side and end elevations of the detection and alarm unit. One or more two-sided, adhesive strips  200  are affixed to the outside of case  125 . These facilitate mounting the detection and alarm unit. Alternatively, the unit can be attached to a surface by screws or rivets, adhesive goo, or left unattached. 
     Microphone  105  may be a standard, air-coupled model DOM-5242L-R, manufactured by Projects Unlimited, of Dayton, Ohio, USA. Alternatively, a contact-type microphone, such as the model CM-1 sold by Sabine, Inc., of Alachua, Fla., USA, or equivalent can be used. Audible alarm  115  may be provided by part number PB-1220PQ, manufactured by Mallory Sonalert Products Inc., of Indianapolis, Ind., USA. Other suitable alarm types include internal or external loudspeakers, vibrators, transmitters, and lamps. 
     Battery  120  is preferably a lithium cell since they have long life. If power supply  150  is used to charge battery  120 , then a rechargeable lithium cell is used. The remaining components are well-known and widely available from a variety of manufacturers. 
     Housing  125  is preferably approximately 10 cm long, 5 cm wide, and 1.5 cm thick overall, although other sizes can be used. Housing  125  is preferably made of polycarbonate, polyamide, or another sturdy plastic material, although wood or metal can be used. Although housing  125  is shown with a rectangular shape, a decorative shape can be used without altering performance of the detector-alarm unit. 
       FIG. 4  shows a block diagram of circuitry  110 . Circuitry  110  senses and discriminates among various water flow sounds, including background (no water sound), leak sounds, and normal water usage sounds (toilet flush, sink usage, etc.). Microphone  105  converts ambient sound to an electrical signal. This signal is amplified by an amplifier  400  and delivered to a filter  405 . Filter  405  is preferably a bandpass filter, although it could also be a high-pass or low-pass filter, depending on the audio characteristics of microphone  105 . Filter  405  preferably has a band pass between 100 and 1500 Hz, although other frequencies and wider or narrower passbands can be used. These concepts are well-understood by those skilled in the art of electrical engineering. 
     Filter  405  is followed by a signal detector  410  that converts the amplitude of the signal from filter  405  to a representative voltage level. An integrator  415  follows detector  410 . Integrator  415  time-averages signals at its input, effectively smoothing the output of detector  410 , thereby preventing large transient signals at its output. If allowed to pass through the circuitry in  FIG. 4 , such transients could cause false alarms. In lieu of an integrator, programming in logic circuit  425  (described below) can time-average each signal type provided by discriminator  420  (also described below). In the event integrator  415  is not used, the output signal of detector  410  is connected directly to the input of discriminator  420 . 
     The output of integrator  415  (if present) is delivered to a level discriminator  420 . Discriminator  420  delivers signals representative of the rate of water flow: no flow, leak flow rate, normal usage flow rate. Signals in the absence of flow include normal background activity, such as voices, traffic, and the like. Many of these signals are removed or reduced by filter  405  and their effect on leak detection is reduced by integrator  415 . Signals indicative of a leak have a low amplitude and are steady. Signals indicative of normal usage flow have a high amplitude, such as occur during the flushing of a toilet and running water in the sink. 
     The output of discriminator  420  is fed to logic circuit  425  and three timers  430 ,  435 , and  440 . Timers  430 ,  435 , and  440  are interval timers. They are activated and reset by logic circuit  425 . Logic circuit  425  also queries timers  430 ,  435 , and  440  to detect whether their preset timing duration has been reached. 
     Timer  430  is a leak timer. It is activated by logic  425  when discriminator  420  detects signals indicative of a leak. It is preset with a duration of T 1 =20 minutes. When logic  425  queries timer  430  and detects that its preset duration has been reached, logic  425  activates alarm  115 . Thus timer  430  permits alarms to occur only for leakage flows lasting longer than 20 minutes, thereby preventing false alarms. 
     Second timer  435  is an alarm-duration timer. It is activated by logic  425  when logic  425  activates alarm  115 . Timer  435  establishes the duration of the alarm cycle, typically T 2 =10 minutes, in the event of a continuous leak. Logic  425  continuously queries timer  435  and when the preset duration T 2  is reached, logic  425  resets itself, timers  430 ,  435 , and  440 , and alarm  115 . This limits the duration of the alarm cycle prevents annoying noises and also lengthens the life of battery  120 . 
     Third timer  440  is an interval timer and establishes a listening period T 3 , typically one minute, during which alarm  115  is silenced and microphone  105  listens for normal usage sounds. Timer  440  is activated by logic  425  when timer  435  is activated. When timer  440  is active, alarm  115  continues to sound. When logic  425  detects that timer  440  has reached its preset period, T 3 , logic  425  silences alarm  115  and permits microphone  105  to listen for normal usage flow sounds. If none are heard, logic  425  re-activates alarm  115  and resets timer  440 . Thus alarm  115  sounds for a period T 3 , is silenced while microphone  105  listens for normal usage flow sounds, then alarm  115  sounds again, resulting in intermittent alarm sounds lasting for durations of period T 3 . 
     The preset durations of timers  430 ,  435 , and  440  can take other values, depending upon the nature of a particular alarm installation. Although use of a single alarm sound is described here, alternative sounds can be selected by logic  425  to indicate the duration of a leak. A first alarm can be indicated by a relatively low-volume alarm sound. Subsequent alarms can be indicated by progressively louder, more strident, or different sounds. 
     An alarm  115  is also connected to logic circuit  425 . Alarm  115  can include a loudspeaker, vibrator, transmitter, and a lamp such as an LED. Any of these alarm modalities can be located within the detector-alarm unit, or externally. If a transmitter is used, additional alarming function is supplied by a receiver (not shown) that is activated when the transmitter sends an alarm signal. 
     Amplifier  400  can have adjustable gain and filter  405  can have adjustable bandpass characteristics. These adjustments permit fine-tuning the detector-alarm unit for a particular application. Logic  425  and timers  430 ,  435 , and  440  can be embodied in a microprocessor. The functions of filter  405 , detector  410 , integrator  415 , and discriminator  420  can be provided by digital or analog electronics, or a combination, as is well-known by those skilled in the art of electrical engineering. 
     FIRST EMBODIMENT 
     Operation 
     FIGS.  5  Through  7   
       FIG. 5  shows one possible placement of the detector alarm unit: inside or outside a toilet tank wall  500 . 
     For the inside case, housing  125  is secured to the left or inside of wall  500  by waterproof adhesive  200 . Microphone  105  detects water flow sounds from within the tank. Housing  125  is placed at a point above the maximum water level in order to keep circuit board  100  and all related components dry. 
     Alternatively, the detector alarm unit can be placed on the right or outside the toilet tank wall. In this case housing  125  is again secured to wall  500  by adhesive  200 . 
     In another alternative aspect, microphone  105  is supplemented or replaced by a contact-type microphone  105 ′. Microphone  105 ′ is connected to circuit board  100  by a wire connection  505 . Microphones  105  and  105 ′ can be connected in series or parallel if sounds from both are to be used. Alternatively, only one microphone is used. 
       FIG. 6  shows another possible placement of housing  125  of the detector alarm unit: secured to a sink or urinal  600 . A water supply line  605  supplies water to sink  600 . As in  FIG. 5 , microphone  105  (not shown in this figure) can be used alone or in combination with an external contact-type microphone  105 ′. In this example, microphone  105 ′ is affixed to supply line  605 . 
       FIG. 7  is a flow chart showing operation of the detector-alarm unit. The unit is placed inside, behind, or on a plumbing fixture such as a toilet tank, urinal, or sink as shown in  FIGS. 5 and 6 , or any other plumbing fixture, such as a tub, shower, etc., which the user desires to monitor for a leak. 
     Operation of the unit begins when it is energized by insertion of battery  120  or connection to power supply  150  ( FIG. 1 ). Logic  425  controls the following sequence of events. Upon power-up (block  700 ), logic  110  resets logic circuit  425 , timers  430 ,  435 , and  440 , and alarm  115  (block  705 ). Alarm  115  is silent when it is in its reset condition. Next, logic  425  monitors the output of discriminator  420  for signal amplitudes that indicate a leak, i.e., amplitudes greater than background noise and less than normal usage level, such as flushing (block  710 ). If a leak is not detected, the system is reset (block  705 ) and the detector-alarm system continues listening. 
     If a leak is detected, i.e., flow sound is greater than background noise and less than normal usage level, logic  425  starts a first timer  430  (block  715 ). Timer  430  is preset with a time-out of T 1 , normally about 20 minutes, although another predetermined time can be selected. This delay prevents false alarms that may occur, such as when flow slows during normal filling of a toilet tank, for example. 
     Next, logic  425  tests to see if time T 1  (20 min. in this example) has been exceeded (block  720 ). If T 1  has not been exceeded, the system listens for activity such as a flush (block  725 ). If there is no flush, i.e., flow sounds remain at the leak level, leak monitoring continues (block  720 ). If the flow sound is greater than or equal to normal water usage level, i.e., a toilet is flushed, the system is reset and leak monitoring is re-initiated. 
     If time T 1  is exceeded during a leak, an alarm condition is sounded and logic  425  starts a second timer  435  (block  730 ). The alarm condition will continue until the second timer&#39;s preset time (10 min. in this example) time T 2  has elapsed (block  735 ). 
     If T 2  has not elapsed, logic  425  starts a third timer  440  that introduces a wait time T 3 , normally on the order of one minute (block  740 ), although other times can be used. 
     After time T 3  has elapsed, logic  425  silences loudspeaker  115  ( FIG. 1 ) (block  745 ) and the system listens to determine if the flow sound is greater than or equal to normal usage level, i.e., a flush has occurred (block  750 ). This is done to prevent continuation of the alarm condition when the condition is no longer detectable. If normal usage levels are not detected (block  750 ), the alarm condition is resumed (block  755 ) and the system waits for the lapse of time T 2 . The loop including blocks  740 ,  745 ,  750 , and  755  continues until normal usage is detected (block  750 ) or time T 2  has elapsed (block  735 ), and results in an alarm sequence of alarm-pause-alarm-pause until the loop is exited. If flow sound is greater than or equal to normal usage level (block  750 ), or time T 2  has elapsed (block  735 ), the sequence of events returns to block  705  and the system is reset to its initial power-up condition. 
     The above-described sequence of events continues as long as the detector-alarm unit is energized. 
     CONCLUSION, RAMIFICATIONS, AND SCOPE 
     The embodiments shown of our water leak detector-alarm unit provide several useful and advantageous features. A water leak is detected audibly by an inexpensive, rugged, disposable, unobtrusive unit. The unit can be placed by an unskilled user and can be hidden behind or within a toilet tank, or behind a sink. No external wiring is required, although it can be provided to extend battery life or eliminate the need for a battery, if desired. When a water leak is detected, the unit sounds an audible or visible alarm, or both. The alarm condition can be transmitted to a remote location by a wire connection or by radio-frequency signaling. 
     While the above description contains many specificities, these should not be considered limiting but merely exemplary. Many variations and ramifications are possible. For example, the unit can be used to detect and alarm for leaks in plumbing other than toilets and sinks, such as swimming pools, aquariums, underground pipes, water purifiers, desalination units, refrigerators with ice makers, dishwashers, and the like. Instead of an intermittent sound, the alarm can be a steady sound whose frequency lies outside the bandpass of the filter used in the detector. Instead of a combination of digital and analog circuitry, all-analog or all-digital circuitry can be used. Alarm sounds can include wailing, beeping, clicking, chirping, and buzzing. Instead of double-stick tape, glue, nails, screws, rivets, and clamps can be used to secure the unit on or near a plumbing fixture. An alarm sound, different from the leak indication sound, can also be used to indicate a low-battery condition. Instead of being reset after the duration of the second timer has elapsed, the alarm can be made to sound or flash lights continuously, dial a predetermined phone number, flash lights or activate sounds at a remote location in case the area is not monitored or occupied. 
     While the present system employs elements which are known to those skilled in the art of water leak detector and alarm design, it combines these elements in a novel way which produces new results not heretofore discovered. Accordingly the scope should be determined, not by the embodiments illustrated, but by the appended claims and their legal equivalents.