Abstract:
A non-intrusive flow detector consists of an optical sensor assembly that attaches non-obstructively and non-invasively to a fluid flow meter. The sensor monitors dial movement of a least flow dial or wheel and generates an electrical signal representative of a flow through the meter. Electrical circuitry having an adjustable timing circuit is used to selectively detect either excessive flow during a predetermined time period or the absence of flow after a predetermined time period. The electrical circuitry is adapted to connect to an existing alarm system and may be housed either near the meter in a separate enclosure or placed in an existing alarm panel.

Description:
FIELD OF THE INVENTION 
   The invention relates to fluid flow detectors for detecting unusual flow volumes and, more particularly, to a non-invasive detector that attaches to existing meters to alert property owners of unexpectedly high or low fluid flow volumes measured by the meters. 
   BACKGROUND OF THE INVENTION 
   Leaks or other unusual events that cause extraordinary flow volumes in piping systems unnecessarily cost residential and commercial property owners money. In addition, leaking water can cause large amounts of damage to a home or commercial space. Water is typically expensive; high utility bills may result from excess or wasted usage. In addition, the growing scarcity of potable water motivates reducing or eliminating waste. 
   Water damage resulting from leaks can cost property owners or insurance companies additional expense. A detector that monitors fluid flow volume and alerts owners, authorities, insurance companies, or a central station when unusual volume is detected may reduce overall utility usage, as well as unnecessary damage and expenses caused by water leaks. Additionally, a small, easily installable, easily operable detector will encourage and facilitate use by property owners. 
   Many current flow meters that measure flow by automatically reading meters are bulky, are designed for technician use only, and do not alert owners to unusual flow volumes. Rather, they merely report actual consumption. Utility meters are often located inaccessibly. For this reason, and to reduce field personnel, utility companies, for instance, find advantage in automatically reading meters electronically, and transmitting the reading, such as by radio waves. 
   U.S. Pat. No. 7,042,368, issued May 9, 2006 to Patterson et al., discloses an automated meter reader to report utility consumption. A device and method of use are described having an optical transceiver that emits light toward a meter face, an optical receiver that accepts light reflected off the meter face, and an amplifier and gain control as part of a signal processing circuit. Patterson et al. do not disclose any means to continuously monitor for unusual flow rates. The meter reader is also obtrusive, blocking ordinary visual inspection of the meter during use. The detector is not designed for property owner use. 
   U.S. Pat. No. 5,214,587, issued May 25, 1993 to Green, also discloses a device for monitoring utility usage. A meter sensor assembly is attached to a meter and a user interface unit with LCD display processes the sensor signal into useful data. This device is less bulky and obtrusive than that of Patterson et al., but it is built to read only meters with rotating discs. Again, it reports consumption, but does not automatically alert a user or other party to unusual usage volumes. 
   Presently available flow detectors that do alert owners to unusual flow volumes are invasive to the meters and piping systems, bulky, and unwieldy for typical owners to install and operate. Whereas automatic meter readers are somewhat non-invasive, leak detectors typically use invasive means such as valve or pipe add-ons. Other detectors use non-centralized systems that do not detect flow starting at the meter where the piping system begins. 
   U.S. Pat. No. 6,317,051, issued Nov. 13, 2001 to Cohen, discloses an invasive flow monitoring device mounted in series with a water pipe, a controller, logic components, and a shut-off valve to shut off water flow when a predetermined condition is met. No meter is read, and actual modifications to existing piping systems must be made. 
   U.S. Pat. No. 5,228,329, issued Jul. 20, 1993 to Dennison, discloses a leak detector that uses a series of thermal fluid flow sensors. These sensors detect leaks indirectly by comparing variations in pipe temperatures caused by variations in flow rate. When leaks are detected, a chime and light emitting diode are activated. 
   It would be advantageous to provide a centralized flow detector to detect flow rates from the beginning throughout an entire piping system. 
   It would also be advantageous to provide a fluid flow detector that continuously monitors the dials on a meter for unusual flow volume. 
   It would further be advantageous to provide an easily installable, easily operable fluid flow detector to facilitate use by a property owner. 
   It would also be advantageous to provide a fluid flow detector with a sensor assembly mechanically adjustable in three planes. 
   It would further be advantageous to provide a fluid flow detector capable of alerting property owners, authorities, insurance companies, or central stations of unusual fluid flow rates. 
   It would also be advantageous to provide a non-invasive fluid flow detector that requires modification to neither existing piping systems nor existing meters. 
   SUMMARY OF THE INVENTION 
   The present fluid flow detector consists of two main elements: an optical sensor assembly attached non-obstructively to a meter for monitoring dial movement and generating electrical signals, and a logic board that can be housed in a small enclosure, or docked in an existing alarm panel, processing the electrical signals and determining whether to activate an alarm device of choice. The detector works with any piping system having a central meter with a dial. Such piping systems include, but are not limited to those containing water, oil, gas, liquid gas, and gasoline. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A complete understanding of the present invention may be obtained by reference to the accompanying drawings when taken in conjunction with the detailed description thereof and in which: 
       FIG. 1  is a top, perspective, schematic view of the face of a typical utility meter having means for attaching a sensor assembly installed thereupon; 
       FIG. 2  is a top, perspective schematic view of the meter face of  FIG. 1  with a sensor assembly in accordance with the invention installed thereon; 
       FIG. 3  is a high-level, system block diagram showing the components of the fluid flow detector; 
       FIGS. 4 and 5 , when taken together, are an electrical schematic diagram of the system of  FIG. 3 ; 
       FIG. 6  is an electrical schematic diagram of the optional reed switch interface of the system of  FIG. 5 ; 
       FIGS. 7   a  and  7   b  taken together are a flowchart depicting the steps of installing and calibrating the flow monitoring system to monitor excessive flow; and 
       FIG. 8  is a flowchart depicting the steps of installing and calibrating the flow monitoring system to detect absence of flow. 
   

   For purposes of brevity and clarity, like components and elements of the apparatus of this invention will bear the same designations or numbering throughout the FIGURES. 
   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring first to  FIG. 1 , there is shown a top perspective view of a typical water meter, generally at reference number  100 . While a water meter  100  is used for purposes of disclosure, the inventive system and method may be applied to other fluids. Consequently, the invention is not limited to water meters but includes flow monitoring of any fluid. Meter  100  typically has several features visible on its face. A meter readout  102 , typically consisting of a series of display wheels, provides a cumulative reading of the volume of fluid passing through meter  100 . Meter  100  typically includes a small flow indicator needle or wheel  104  that typically revolves relatively rapidly as fluid flows through meter  100 . The inventive flow monitoring system relies on monitoring the movement of small flow indicator  104 . 
   A threaded stud  106  having a lower mounting portion  108  is affixed to the face of meter  100 , typically using an adhesive applied to a lower surface  110  of lower mounting portion  108 . It will be recognized that any suitable method including, but not limited to, welding, gluing, fastening by a hook-and-loop fastening arrangement, magnetically fastening, bolting, clamping, or otherwise attaching may be used to affix threaded stud  106  to meter  100 . However, meter readout  102  must not be obscured by threaded stud  106  or mounting portion  108  thereof. Threaded stud  106  may be formed from a stainless steel welding stud known to those of skill in the welding art. 
   Some meters  100  may have a sweeping hand  112 . Sweeping hand  112  is irrelevant to the overall functioning of the inventive flow sensor except for considerations arising from sweeping hand  112  passing between optical sensor assembly  114  ( FIG. 2 ) and small flow dial  104 . This potential problem is discussed in detail hereinbelow. 
   Referring now also to  FIG. 2 , there is shown a top, perspective view of meter  100  with a sensor assembly  114  mounted to threaded stud  106 . A slotted, L-shaped bracket  116  is placed over threaded stud  106  and secured by a wing nut  118  or another equivalent fastening device. 
   Slotted optical sensor assembly  114  is slidably secured to an upwardly projecting portion  120  of slotted bracket  116 , typically by a screw or bolt  122  through a slotted portion of optical sensor assembly  114  into upwardly projecting bracket portion  120 . Screw or bolt may be captured by threads, not shown, in a hole, not shown, in upwardly projecting portion  120  of bracket  116 . Alternately, a nut or other fastener may be placed on a distal end of screw or bolt  122  thereby securing optical assembly  114  to bracket  116 . 
   A cable  124  carries electrical power and electrical signals to and from optical sensor assembly  114 . 
   Optical sensor assembly  114  is typically a one-piece mechanical assembly containing both a light source (e.g., an LED) and a photo detector (e.g., a phototransistor). The light source shines outwardly from the body of optical sensor assembly  114  to a prefocused spot. Light reflected from an object proximate the prefocused spot is received by the photodetector that, in turn, generates an electrical signal representative of the magnitude of the reflected light thereof. The operation of optical sensor assembly  114  is described in detail hereinbelow. 
   Referring now to  FIG. 3 , there is shown a functional block diagram of the electrical circuitry of the fluid flow detector and monitor, generally at reference number  300 . 
   Sensor assembly  114  ( FIG. 2 ) is connected via cable  124  ( FIG. 2 ) to the input of a low-pass amplifier  302 . A first output of low-pass amplifier  302  is connected to a full-wave rectifier  304 . An output of full-wave rectifier  304  is connected to an LED bar graph driver  306 . The output of LED bar graph driver  306  is connected to an LED bar graph display  308 . 
   A second output of low-pass amplifier  302  is connected to an input of a window comparator  310 . An output of window comparator  310  is connected to an input of a one-shot, retriggerable multivibrator  312 , often referred to as a single-shot by those skilled in the electrical design arts. In the embodiment chosen for purposes of disclosure, single shot  312  is crystal controlled. It will be recognized by those skilled in the art that numerous other approaches to stabilizing a single-shot may be substituted therefor. 
   In alternate embodiments of the inventive flow-monitoring device, a reed switch  314  may be included within meter  100  ( FIG. 1 ). Reed switch  314  typically provides a contact closure once per a predetermined number of gallons or cubic feet of flow through meter  100  and may be used to eliminate optical sensor assembly  114  as well as certain electronic components. When used, reed switch  314  is connected to an alternate input of single-shot  312 . 
   A binary input set T 1   316  is connected to a set input of one-shot  312 . T 1   316  typically consists of a series of DIP switches used to set the period of one-shot  312 . 
   A master reset switch  318  is connected to a reset input of one-shot  312 . 
   An LED indicator  320  is attached to an output of one-shot  312 . While a yellow LED indicator  320  is chosen for purposes of disclosure, it will be recognized that other indicators and/or colors may be substituted therefor. 
   The primary output of one-shot  312  is connected to the input of a timer  322 . 
   A second set of DIP switches forming binary input set T 2   326  is connected to timer  322 . Binary input set T 2   326  controls the time setting of timer  322 . 
   An LED indicator  324  is connected to an output of timer  322 . While a red LED has been chosen for purposes of disclosure, it will be recognized that other indicator types and/or colors may be substituted therefor. 
   A relay  328  is connected to a primary output of timer  322 . For purposes of disclosure, relay  328  has an s.p.d.t. contact configuration. It will be recognized that other switch configurations, of course, may be substituted for the s.p.d.t. configuration. It will also be recognized that while an electromechanical relay has been chosen for purposes of disclosure, a wide range of triggerable switching devices known to those of skill in the art may be effectively substituted when desired. 
   Referring now also to  FIGS. 4 and 5 , there is collectively shown an electrical schematic diagram of an embodiment of the system of  FIG. 3 , generally at reference numbers  400   a ,  400   b.    
   The optical sensor  114  consists of two portions: an infrared light emitting diode (IRLED)  402 , and a phototransistor  404 , typically provided in a single mechanical package. IRLED  402  and phototransistor  404  are typically held aligned in a pre-focused arrangement to facilitate installation. 
   Low-pass amplifier  302  is implemented by AC coupled amplifiers  406 ,  408  and associated circuitry. 
   Window comparator  310  is implemented by amplifiers  410 ,  412  and associated circuitry enables detection of increases and decreases in reflected light when the voltage of the generated electrical signal surpasses a predetermined threshold. The imposed threshold reduces false alarms caused by electrical noise, and is set by resistors  414 ,  416 , and diodes  418 ,  420 . 
   Full-wave rectifier  304  is implemented as a voltage doubler arrangement  426  consisting of capacitors  428 ,  434 , diodes  430 ,  432  and resistor  436 . The output of this arrangement is applied to an LED bar graph driver  306 , which controls an LED bar graph indicator  308 . 
   One-shot  312  and timer  322  each have a switch  406 ,  408 , respectively used to determine whether counting is in seconds or minutes. 
   One-shot  312  and timer  322  each have DIP switch sets  316 ,  326  respectively, enabling a user to manually program time delays. Each individual switch  316   a - 316   h  and  426   a - 426   h  represents a binary value. Such arrangements are believed known to those of skill in the art and are not described further herein. Switches  316   a - 316   h  and  426   a - 426   h  are used to set user-selected time periods for one-shot  312  and timer  322 , respectively. 
   One-shot  312  and timer  322  may be controlled by crystals  410 ,  412 , respectively, appropriately connected to each thereof. It will be recognized by those of skill in the art that other devices and/or circuits may be utilized to provide necessary stability to one or both of one-shot  312  or timer  322 . Consequently, the invention is not limited to the crystal controlled time stabilization method chosen for purposes of disclosure. 
   Referring now also to  FIG. 6 , there is shown an electrical schematic of an interface circuit that accepts a contact closure from reed switch  314 , typically forming part of meter  100  ( FIG. 1 ). A current-limiting resistor  438  is placed in series with a 12 volt DC power source, and optical coupler or opto-isolator  440  and the contacts of reed switch  314 . The output of opto-isolator  440  is coupled to the one-shot  312  at contact  442  as seen in  FIG. 5 . It will be recognized that all circuitry of  FIG. 4  may be eliminated in the embodiment using reed switch  314  as an input from meter  100  ( FIG. 1 ). 
   In operation, the flow monitoring system of the invention accepts an electrical signal from sensor form optical sensor assembly  114 . Optionally, a pulse from may be generated by reed switch  314  within meter  100  ( FIG. 1 ) or another external signal source calibrated to flow through meter  100 . 
   The electrical signal from optical sensor assembly  114 , more particularly from photodetector  404 , is amplified and shaped by low-pass amplifiers  302 . The output from low-pass amplifiers  302  is provided to window comparator  310  that acts as a threshold detector. This signal processing provided by low-pass amplifiers  302  and window comparator  310  provides a clean signal responsive to the signal generated by photodetector  404 . 
   An output signal from low pass amplifier  302  is passed to a full wave rectifier circuit  426  that provides a DC signal proportional to the signal from photodetector  404  to the LED bar graph driver  306 . LED bar graph driver  306  provides the necessary drive signals to an LED bar graph display  308 . LED bar graph display  308  is used primarily to position the optical sensor assembly  114  ( FIG. 2 ) and to calibrate the sensitivity of the flow monitoring system  300  ( FIG. 3 ) to desired flow levels and/or time periods. 
   The output window comparator  310  also triggers one-shot  312  whose period is set by binary input dip switches  316   a - 316   h . A trigger at the input of one-shot  312  starts a timeout of period T 1  determined by the settings of dip switches  316   a - 316   h . During the T 1  time period, yellow LED  320  is illuminated. Each pulse from window comparator  310  re-triggers one-shot  312 . Consequently, if input pluses are supplied frequently (for example, when flow through meter  100  is high), the output of one-shot  312  remains active. 
   The output of one-shot  312  also starts delay timer  322 . Delay timer  322  has a time period T 2  set by binary input dip switches  326   a - 326   h . Delay time  322  operates during the time an input is applied. If an input is still applied at the end of the time period, delay timer  322  generates an output signal. If, however, the input to delay timer  322  is removed prior to the end of time period T 2 , delay timer  322  is reset and no output signal is generated. Consequently, if the output of one-shot  312  goes inactive prior to the time-out of delay timer  322 , no alarm is generated. However, a continued, active state of one-shot  312  after delay time T 2  causes an output signal from delay timer  322  to activate relay  328 , thereby triggering an alarm. 
   Assume: 
   Tp is the time between input pulses from optical sensor assembly  114  (or reed switch  314 ); 
   T 1  is the time period of one-shot  312 ; 
   T 2  is the delay time of delay timer  322 ; and 
   T 2 &gt;T 1 . 
   With these assumptions if Tp&gt;T 1 , no alarm is generated. However, if Tp&lt;T 1 , an alarm is generated. 
   The difference in time setting between T 1  and T 2  determines how many Tps (with Tp&lt;T 1 ) are required to cause an alarm. For example, if T 2 =3×T 1 , then at least 3 Tps must occur before delay timer  322  generates an output and causes an alarm. 
   Each model of meter  100  may require a unique calibration to convert pulses-per-second into gallons or cubic feet per minute. 
   The flow monitoring system of the invention may operate in two different modes. First, as described hereinabove, the system can detect excessive flow. The user need set only dip switches  316   a - 316   h  and  326   a - 326   h  to appropriate values commensurate with the particular meter upon which optical sensor assembly  314  is installed and the flow at which an alarm is desired. 
   In an alternate mode of operation, monitoring system  300  can be utilized to provide an underflow alarm. In Applications such as irrigations systems, water flow may be intermittent. However, if flow is not reestablished in a timely manner (e.g., one hour), damage to crops may occur. The inventive flow monitoring system may be utilized to generate an alarm if flow is not reestablished after a predetermined time. 
   Assume that the normally open (n.o.) contacts of relay  328  are used in an application when overflow is to be detected. In other words, when delay timer  322  finally generates a signal after timeout, the n.o. contacts of relay  328  close, thereby completing an alarm circuit. By setting T 1  to, for example, one hour and T 2  to zero, as water flows, one-shot  312  is triggered repeatedly and delay time  322  time out immediately activates relay  328  and opens the normally closed (n.c.) contacts thereof. If an alarm circuit is connected to the n.c. contacts, relay  328  remains energized for one hour after the last pulse is received from optical sensor assembly  114 . If water flow is reestablished within the one hour time period (T 2 ), relay  328  remains energized and no alarm signal is generated. If, however, flow is not reestablished, at the end of the one hour timeout, relay  328  is deenergized and the n.c. contact closes thereby generating an alarm signal. By adjusting the value of T 1  using dip switches  316   a - 316   h  any time delay up to approximately 255 minutes (i.e., 4.25 hours) may be programmed. 
   The circuitry of  FIGS. 4 ,  5  and  6  is typically packaged on a circuit board, not shown, that may be housed in a separate housing disposed near meter  100 . The circuitry of the inventive flow meter is adapted for seamless integration into existing alarm systems known to those of skill in the art. In alternate embodiments, such a circuit board may be placed in an existing meter cabinet. 
   Referring now to  7   a  and  7   b  as well  FIGS. 1 and 2 , there is shown a flow chart of the installation and set-up process for installing optical sensor  114  on meter  100  and calibrating the electrical portion of the system  300  ( FIG. 3 ), generally at reference numbers  700   a ,  700   b , respectively. 
   The user or installer first attaches threaded stud  106  to meter  100 , step  702 . Any appropriate technique such as soldering, welding, gluing, fastening by a hook-and-loop fastening arrangement, magnetically fastening, bolting, clamping, or otherwise attaching threaded stud  106  to meter  100  may be used. Threaded stud  106  must be mounted in such a manner that dial  102  on meter face  108  is not obstructed. 
   After threaded stud  106  is attached to meter  100 , step  702 , optical sensor assembly  114  is attached thereto using slotted bracket  116 . A slot in the transverse portion of slotted bracket  116  is placed over threaded stud  106  and loosely secured thereto with wing nut  118  or another suitable fastener, step  704 . Slotted bracket  112  may rotate on threaded stud  112  as well as move inward and outward along the slot thereby providing adjustment along the x-y axes. Slotted optical sensor  114  is attached to the upright portion of slotted bracket  116  using screw  122  and, when required, an appropriate fastener such as a nut, not shown. Movement of slotted optical sensor  114  along the upright portion of slotted bracket  112  allows adjustment along the z-axis. 
   Water flow is next initiated, step  706 . Water flow is typically initiated by opening a faucet in the piping system downstream from meter  100 . With water or other fluid flowing through meter  100 , the position of optical sensor assembly  114  relative to small flow indicator  104  may be adjusted and optimized, step  708 . It is important to note that before final sensor adjustment is made that large, sweeping hand  112  is not positioned between the sensor assembly  114  and small flow indicator needle or wheel  104 . If sweeping hand  112  is so positioned, water should be allowed to flow until small flow indicator  104  is unobstructed by sweeping hand  112 . Otherwise, optimum adjustment of sensor assembly  114  is difficult or impossible potentially resulting in reduced sensitivity of the inventive flow detector to water flow through meter  100 . 
   This is accomplished by rotating and sliding slotted bracket  116  on stud  106  and moving sensor assembly  114  up and down along the upright portion  120  of slotted bracket  116 . LED bar graph  308  ( FIG. 3 ) may be used to optimize the position of optical sensor  114  with respect to small flow indicator  104  of meter  100 . 
   A maximum indication from LED bar graph  308 , typically a full-scale display (i.e., all bars illuminated), indicates a good alignment of optical sensor assembly  114  with small flow indicator  104 . If a maximum reading (i.e., most bars illuminated) is not obtained, step  710 , optical sensor assembly  114  is readjusted, step  708 . 
   If a maximum reading of LED bar graph  308  is obtained, however, step  710 , water flow is reduced, step  714 , and optical sensor assembly  114  is again adjusted in the x-, y- and z-axes, step  716 . 
   If a maximum reading is still not obtained, step  718 , the optical sensor assembly adjustment process is repeated, step  716 . 
   Once the adjustment of optical sensor assembly  114  is optimized, step  718 , all hardware securing optical sensor assembly  114  to stud  106  is tightened, step  722 . Mounting hardware includes mounting screw  122 , wing nut  118 , and any other additional or substitute hardware, not shown. 
   Water flow is adjusted to the flow rate for which an alarm signal is desired and both T 1  and T 2  times are set to zero, step  724 . T 1  and T 2  times are set using dip switches  316 - 316   h  and  326   a - 326   h , respectively. Time is incrementally added to T 1  using DIP switches  316   a - 316   h  until yellow LED  320  flashes intermittently, step  726 . Additional time is added to T 1  until yellow LED  320  is illuminated continuously, step  728 . 
   Delay time T 2  is set to a desired multiple of T 1  or to any other time period the user wishes to delay reporting an alarm when the current flow conditions are encountered, step  730 . Typical considerations made in selecting a T 2  delay time are based on water flow events encountered in the water distribution system being monitored. For example, devices such as icemakers draw water at random time intervals. In heating system utilizing a boiler, make-up water may occasionally be drawn from the water distribution system. T 2  is adjusted to prevent an alarm condition being reported under such occurrences. 
   Once the installation and calibration procedure  700  is complete, step  732 , the novel flow monitor may be considered in service. 
   As discussed hereinabove, the novel flow monitoring system may also be used to detect lack of fluid flow (i.e., underflow). Refer now again to  FIGS. 1 and 2 . Referring now also to  FIG. 8 , there is shown a flow chart of the installation and set-up process for installing optical sensor  114  on meter  100  and calibrating the electrical portion of the system  300  ( FIG. 3 ), generally at reference number  700 . 
   Once steps  702  to  722  have been performed as described in detail hereinabove, step  802 , the water flow is set to the desired flow, the absence of which is to be detected, step  804 . Time period T 1  is next set to the maximum time that the absence of flow is tolerable, step  806 . Next, time period T 2  is set to zero, step  808 . 
   If, after setting periods T 1  and T 2 , steps  806 ,  808 , respectively, both red LED  324  ( FIG. 3 ) and yellow LED  320  ( FIG. 3 ) are illuminated, step  810 , the flow monitoring system is armed and ready, step  812 , and the set-up process is complete, step  814 . Relay  328  ( FIG. 3 ) is now energized. 
   If, however, both red LED  324  and yellow LED  320  are not illuminated, step  810 , then step  802  is repeated until optical sensor assembly  114  ( FIG. 1 ) is properly installed and adjusted. 
   Since other modifications and changes varied to fit particular operating requirements and environments will be apparent to those skilled in the art, the invention is not considered limited to the example chosen for purposes of disclosure, and covers all changes and modifications which do not constitute departures from the true spirit and scope of this invention. 
   Having thus described the invention, what is desired to be protected by Letters Patent is presented in the subsequently appended claims.