Abstract:
A water flow-sensing device includes an assembly with a stationary metering rod with a cylindrical portion and a conical portion and a relatively moveable element in the shape of a hollow cylindrical toroid. The relatively moveable element is biased by a spring to a rest position wherein the cylindrical portion of the stationary metering rod blocks flow through the relatively moveable element. During fluid flow, fluid pressure moves the relatively moveable element so that the conical portion of the stationary metering rod is within the hollow portion of the relatively moveable element thereby creating a flow area and allowing flow therethrough. A toroidal ferrite is biased against the relatively moveable element and moves in unison therewith. The position of the toroidal ferrite is electromagnetically determined thereby allowing for a calculation of the fluid flow therethrough. Low flowrates indicative of a trickle leak and large flowrates indicative of a large leak can be detected. After predetermined periods of time of the detection of unacceptable flowrates, a ball valve is activated to terminate flow.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This is a continuation-in-part of application Ser. No. 09/262,881, filed Mar. 8, 1999, now abandoned, the entire disclosure of which is incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to automatic water shut off valves for measuring the flow of water through the valve and shutting off the flow of water in response to a predetermined flow condition. 
     BACKGROUND OF THE INVENTION 
     It is known to provide automatic water shut off valves that have the ability to sense a water leak and automatically close the valve so as to prevent further leakage and damage. See for example, the disclosures found in U.S. Pat. Nos. 5,771,920 and 5,794,653, the disclosures of which are expressly incorporated by reference. While such automatic water shut off valves are known, many have not had the ability to sense both very small trickle leaks and large catastrophic leaks with great reliability. Further, some of the automatic water shut off valves of the prior art are mechanically cumbersome and very expensive to manufacture and maintain. Therefore, there is and continues to be a need for an automatic water shut off valve that is of a relatively simple design that has the ability to sense and detect relatively small trickle leaks as well as large catastrophic leaks and to shut off the associated valve in response to detecting either. 
     Water leakage detection systems are generally effective to stop the leakage once the leakage problem has been detected. However, water leakage detection systems of the prior art have done very little to minimize the damage caused by a leak once the leak has indeed occurred. In cases where the home or building is attended, then once a leak occurs and the main supply of water has been shutoff, then steps can be taken to remove standing water from areas and do whatever is required to minimize the damage. The problem comes into play when there is a leak, especially a catastrophic leak, in a home or building that is unattended. For example, a catastrophic leak even though detected and stopped can leave standing water on hardwood floors, for example. If the standing water remains on the hardwood floors for any significant amount of time, one can expect the floor to buckle and be so severely damaged that a new floor is required. 
     Therefore, there is a need for a water leakage detection system that will communicate the existence of a leakage to a central clearing station, such as a security service, if a home or building is unattended. The reporting of a leak to a central clearing center will permit the away homeowner to be contacted or even a repair service to be contacted so that the water damage can be immediately cleared and the problem causing the leak repaired. 
     SUMMARY OF THE INVENTION 
     The problems of the prior art are solved by providing a flow sensor assembly comprising a stationary metering rod with a cylindrical portion and a conical portion. A movable toroidal sensing disk circumferentially engages the cylindrical portion of the stationary metering rod during zero or low flow conditions resulting in high sensitivity at low flowrates. The liquid flows through the annular space between the stationary metering rod and sensing disk. However, at higher flowrates, the toroidal sensing disk is urged to a position circumferentially outward from the conical portion of the stationary metering rod thereby creating a larger flow cross section between the stationary metering rod and the sensing disk resulting in a decrease in sensitivity of the sensor while greatly increasing the range without excessive pressure drop. The movement of the toroidal sensing disk translates into movement of a spring-biased longitudinally adjacent toroidal ferrite. The ferrite has a high magnetic permeability and the position thereof affects the resonate frequency of a coil circumferentially wound about an exterior of the sensor tube. The resonant frequency is measured by a microprocessor which thereby calculates a flowrate based on the known flow/deflection characteristics of the sensor. 
     The microprocessor is programmable to respond differently to different flow rates. For example, a sudden large increase in the flow for more than ten to twenty minutes would be indicative of a catastrophic leak and the microprocessor could be programmed to shut the valve. Additionally, a long term low volume flow would be indicative of a trickle leak and the microprocessor could be programmed to shut the valve in this instance as well. Other acceptable flow conditions could also be programmed, for example, watering the lawn. 
     The microprocessor is further preferably connected to a security controller which in turn is connected to a remote station such as a security service computer or the like. Detection of a leak would trigger an alarm at the remote station resulting in the security service calling a plumber or the like as needed. The microprocessor could furthermore be integrated into the security controller if desired. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein: 
     FIG. 1 is a cross-sectional view of the sensor of the present invention in the zero flow configuration; 
     FIG. 2 is a cross-sectional view of the sensor of the present invention in the high flow configuration; 
     FIG. 3 is a diagram of the oscillating coil apparatus for determining ferrite position; 
     FIG. 4 is a diagram of the linear variable differential transformer apparatus for determining ferrite position; 
     FIG. 5 is an exploded perspective view of the sensor of the present invention; 
     FIG. 6 is a block diagram illustrating the sensor of the present invention being connected to a security system; and 
     FIG. 7 is a block diagram illustrating an alternative design for connecting the sensor to a security system. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings in detail wherein like numerals indicate like elements throughout the several views, one sees that FIG. 1 shows sensor  10  with a flow passage defined by cylindrical hollow inlet tube  12 . Fluid enters through opening  14  of inlet tube  12 . Flow is controlled by a rotationally seated ball valve  16 . Ball valve  16  is generally spherical with channel  18  which is aligned with inlet tube  12  thereby permitting flow as shown in FIG. 1 or turned to be perpendicular with inlet tube  12  thereby inhibiting flow. Ball valve  16  further includes stem  20  which is journaled for rotation in passageway  22  which is formed on the cylindrical wall of inlet tube  12 . As shown in FIG. 5, stem  20  is affixed to gear  24  which is driven by step-down cluster gear assembly  26  or can be manually driven, both of which will be described in detail hereinafter. The ball valve  16  thereby functions as a shutoff valve for the water line. 
     Liquid flows through channel  18  of ball valve  16  in the open position and passes through channel  28  of inlet tube  12 . Channel  28  includes conical outwardly flared section  29 . Wall portion  30  surrounding channel  28  has a portion  32  of reduced diameter in order to allow portion  32  to be received within opening  34  of hollow cylindrical sensor tube  36 . Opening  34  includes cylindrical stop  38  of reduced diameter to limit insertion of inlet tube  12  into sensor tube  36 . Sensor tube  36  is typically molded plastic although those skilled in the art will realize that other materials may be suitable for this purpose. 
     The internal diameter of sensor tube  36  is preferably matched to the outermost diameter of conical outwardly flared section  29  of channel  28  of inlet tube  12 . 
     Toroidal sensing disk  42  is slidably engaged within the internal diameter of sensor tube  36 . Flow between sensor tube  36  and toroidal sensing disk  42  is prevented by seal washer  44  which is affixed to toroidal sensing disk  42  and is urged against the inside diameter of sensor tube  36 . 
     Toroidal ferrite  46 , which has a high magnetic permeability, with internal passageway  48  is urged against toroidal sensing disk  42  by coil spring  50 . Together, toroidal sensing disk  42  and toroidal ferrite  46  form an axially movable sleeve, which moves along the axis of the water line. Internal passage  48  or toroidal ferrite  46  is aligned with passageway  52  of toroidal sensing disk  42  and preferably somewhat larger in diameter. Coil spring  50  additionally urges against relatively stationary sensor tube adapter  51  which is received within outlet opening  53  of sensor tube  36 . The Hooke&#39;s constant of coil spring  50  can be varied to vary the sensitivity of sensor  10 . 
     Metering rod  54  includes cylindrical portion  56  and conical portion  58  and is stationary within sensor tube  36  as affixed by spoked support  59 . Spoked support  59  defines the resting or zero flow position of toroidal sensing disk  42  as shown in FIG.  1 . In this resting or zero flow configuration of FIG. 1, cylindrical portion  56  is engaged within passageway  52  of toroidal sensing disk  42  and all flow must take place through a very small annular space between toroidal sensing disk  42  and stationary metering rod  54  which results in a pressure differential across toroidal sensing disk  42 . The lack of tapered surfaces between the cylindrical portion  56  of metering rod  54  (both of which are precisely machined) and toroidal sensing disk  42  and between the toroidal sensing disk  42  and the interior of sensor tube  36  in the resting or no flow position of toroidal sensing disk  42  provides a large initial displacement of toroidal sensing disk  42  at very low flowrates, such as may occur during a trickle leak. During high flow conditions, this pressure differential exerts a force in the direction of flow which displaces toroidal sensing disk  42  and toroidal ferrite  46  to the position illustrated in FIG. 2 whereby conical portion  58  of metering rod  54  is within passageway  52  of toroidal sensing disk  42  thereby increasing the area within passageway  52  available for flow. Thus metering rod  54  acts as a sleeve insert for the sleeve formed by the sensing disk  42  and the ferrite  46 . When the sensing disk  42  abuts the sleeve insert  54 , a no-flow condition exists. However, when water pushes against the sensing disk  42 , and spring  50  compresses, flow area is created, and a flow condition exists. Water then flows around the insert  54  and through the sleeve. 
     Coil  60  is wrapped around the exterior of sensor tube  36  outward from the zero flow position of toroidal ferrite  46  as shown in FIG.  1 . Coil  60  is in electric and electronic communication with CPU and associated interface circuitry  62  (see FIG. 3) and is configured to detect the position of toroidal ferrite  46  thereby permitting CPU  62  (with associated interface circuitry) to calculate the flow through sensor  10  based on known flow/deflection characteristics of sensor  10 . Collectively, the coil  60 , the ferrite  46  and the central processor  62  form a transducer which converts the movement of the sleeve into a measurement of the water flow through the shutoff valve. Note that the central processor  62  is programmable to allow different threshold flow rates for certain periods of time to trigger the closure of ball valve  16 . 
     Coil  60  can operate on one of two principles—electronic detection with a simple oscillating coil or electronic detection linear variable differential transformer (LVDT). 
     The use of a simple oscillating coil  60  is illustrated in FIG.  3 . Coil  60  is wound circumferentially around sensor tube  36  over the zero flow position of toroidal ferrite  46  (FIG.  1 ). The length of coil  60  is likewise similar to the length of toroidal ferrite  46 . Coil  60  is an inductive component in an electronic oscillating circuit. As toroidal ferrite  46  moves with respect to coil  60 , the frequency of oscillation of coil  60  changes proportionately thereby providing a quantification of the distance toroidal sensing disk  42  has moved with respect to stationary metering rod  54  and, consequently, the resulting flow area between toroidal sensing disk  42  and stationary metering rod  54  and the pressure differential across toroidal sensing disk  42 . This results in a calculation of the flowrate through sensor  10 . As shown in FIG. 3, the position of the coil  60  is preferably offset a small distance with respect to the rest position of toroidal ferrite  46 , such as one sixteenth of an inch in the opposite of the fluid flow direction. This ensures that a small initial movement of toroidal ferrite  46  in the direction of flow, such as may occur during a trickle leak circumstance, is detected by an appropriate unidirectional change in the oscillation frequency of coil  60 . 
     The use of a linear variable differential transformer (LVDT) configuration is illustrated in FIG.  4 . Linear variable differential transformers are wound coil, electromagnetic devices which are used to translate the linear movement of a ferromagnetic armature into an AC voltage which is linearly proportional to the armature position. As implemented in FIG. 4, linear variable differential transformer  62  includes primary coil  60 ′ centrally located about secondary coils  64 ,  66 . Primary coil  60 ′ is excited by an AC voltage which is set at a specific amplitude and frequency (which is known as the primary excitation). Primary coil  60 ′ induces a variable voltage in secondary coils  64 ,  66  as toroidal ferrite  46 , which acts as a ferromagnetic plunger, moves axially within the coils  60 ′,  64 ,  66 . The electrical output of LVDT  62  is the differential AC voltage between the two secondary coils  64 ,  66 , which varies with the axial position of toroidal ferrite  46  within LVDT  62 . Typically, this AC output voltage is converted by suitable electronic circuitry to high level DC voltage or current which is more convenient to use. The amplitude of the resultant voltage is proportional to the position of toroidal ferrite  46 , while the phase sense of the voltage indicates direction of movement from a reference zero position. Secondary coils  64 ,  66  are connected in opposite to produce zero voltage output when toroidal ferrite  46  is at the resting (no flow) position. As toroidal sensing disk  42  and toroidal ferrite  46  move away from one secondary coil and closer to another secondary coil, the induced voltage between the primary coil  60 ′ and the respective secondary coils changes thereby allowing for a precise calculation of the position of the toroidal ferrite  46  and hence the flowrate through sensor  10 . 
     The advantages of the use of coil  60 , either as a simple oscillating coil or as a LVDT, are low cost, high sensitivity to very low flowrates while maintaining a broad flow range (thereby permitting detection of both trickle leaks and catastrophic leaks), an electronic interface and low cost manufacturing practices. 
     FIG. 5 illustrates how the ball valve  16  is closed in response to the detection of either a trickle leak or a catastrophic leak. Sensor  10  is contained within a housing formed from halves  70 ,  72 . Half  72  includes key aperture  73  which allows a user to insert a key (not shown) and manually drive gear  24  to open or close ball valve  16  (see FIG.  1 ), such as during an electrical power outage. Half  72  further includes screw apertures  75 , to allow screws  77  to fasten halves  70 ,  72  to each other. When CPU and associated interface circuitry  62  determines that an unacceptable flowrate has continued for an unacceptable period of time (this unacceptable period of time or threshold can be dependent upon the flowrate, so that the threshold associated for a trickle leak can be different from the threshold associated with a large or disastrous leak and intermediate flowrates may have no threshold as such flowrates may be indicative of normal use), CPU and associated interface circuitry  62  activates motor  74  which through step-down cluster gears assembly  26  turns gear  24  which turns stem  20  and ball valve  16  one-quarter turn to the closed position. CPU and associated interface circuitry  62  can likewise effect the rotation of ball valve  16  to an open position in response to a user command. 
     The sensor or water valve assembly  10  may further be incorporated into a home security system, as shown in FIGS. 6 and 7. Specifically, FIG. 6 shows a personal computer  100 , which may be used to program a security controller  102  and an intermediate controller  104 . The intermediate controller  104  controls the sensor or water valve assembly  10 , and thus valve  16 , which allows water to flow therethrough to household water uses such as a toilet  106 , a shower  108  or a sink  110 . The security controller  102  is connected via a conventional phone line to a remote station  112  such as a security service. The security controller  102  is independently programmable as is the intermediate controller  104 , but greater flexibility in the programming is possible through the PC  100 . Alternatively, the intermediate controller  104  may be integrated into the security controller  114  as seen in FIG.  7 . All other aspects remain the same. 
     In the preferred embodiment, the security system is programmed either through the PC  100  or the controllers  102  and  104  to have a home mode and an away mode. In the away mode, the thresholds for leak detection may be lower since the away mode assumes that the people normally inhabiting the home are away, and consequently water consumption or use by them would be expected to be zero. Allowances can be programmed for incidental water flow as well as other periodic water uses such as lawn irrigation. 
     In the home mode, the thresholds would be higher as would be expected through everyday use including showers, laundry, dish washing, and the like. As noted above, the PC  100  or the intermediate controller  104 , which includes the CPU  62 , could be programmed to have a plurality of thresholds which reflect different acceptable uses. This provides great flexibility to the homeowner, who does not have to worry about false alarms, yet at the same time, it provides peace of mind in that any unusual use will trigger an alarm at the remote station  112  and shutoff valve  16  to arrest the flow of water in the water line. 
     In use, when the sensor  10  detects a leak and actuates the shutoff valve  16 , it simultaneously sends a signal to the security controller  102  in the embodiment illustrated in FIG. 6 or to the security controller  114  in the embodiment shown in FIG.  7 . Once the leak signal is received by the security controller, the security controller then directs a signal or some form of a communication to the remote station  112 , identifying that a leak has been detected at a certain homeowner&#39;s residence. At this point, a number of events can happen. First, the remote station can contact the homeowner who has previously identified his or her whereabouts during this away period. Further, the homeowner may have identified a plumber or other repair service that would be on call for such situations and accordingly upon the occurrence of a leak and the receipt of that information by the remote station, the plumber or the repair service is called. Finally, the homeowner may have designated other individuals to be called in the event of any type of alarm including the detection of a leak within the home. 
     Thus the several aforementioned objects and advantages are most effectively attained. Although preferred embodiments of the invention have been disclosed and described in detail herein, it should be understood that this invention is in no sense limited thereby rather its scope is to be determined by that of the appended claims.