Abstract:
A flow meter and electrically operable valve assembly having an integral flow meter provide detection of very low water flows along with ease of installation and compact packaging for a water supply control system. The flow is particularly useful for systems that control household water supplies to prevent flooding, but is also useful in other applications such as agricultural and industrial systems where low water flow rates must be determined. All of the controls and features are integrable within a compact package that occupies essentially the same volume and piping space as a conventional electrically operable valve.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    The present application is related to concurrently filed U.S. patent applications: Ser. No. __/______ entitled “METHOD AND SYSTEM FOR CONTROLLING A HOUSEHOLD WATER SUPPLY” and Ser. No. __/______ entitled “ELECTRICALLY OPERABLE VALVE ASSEMBLY HAVING AN INTEGRAL PRESSURE REGULATOR”, the specifications of which are herein incorporated by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates generally to liquid flow meters, and more specifically, to a positive flow meter for incorporation within an electrically operable valve assembly for controlling a water supply.  
           [0004]    2. Background of the Invention  
           [0005]    Water supply control systems for household use generally require a measure of water flow, so that water leaks may be detected. Typical flow meters use a paddle or other device inserted into the liquid flow. Displacement of the paddle against a restoring force provides a linear or angular measurement of the flow amount. However, paddle type flow meters generally cannot measure the low flow rates associated with slow water leaks.  
           [0006]    A water supply control system also generally requires an electrically operable valve to control water flow and other devices such as a pressure regulator and backflow preventor. The combination of all of these devices along with a flow meter makes a very large in-line installation in a typical water supply control system and requires a number of connections, each that may be susceptible to failure. Assembly time is also increased when the devices used are discretely installed in-line.  
           [0007]    Therefore, it would be desirable to provide a flow meter for measuring low flow rates associated with small leaks. It would further be desirable to provide a flow meter that may be integrated with other devices such as electrically controllable valves, backflow preventors and pressure regulators, whereby fewer interconnects, smaller in-line installation space and less assembly time is required.  
         SUMMARY OF THE INVENTION  
         [0008]    The above objective of providing a flow meter for measuring low flow rates that does not require additional in-line space, additional interconnects and assembly time is achieved in a positive flow meter that may be constructed integral to an electrically controllable valve, pressure regulator and backflow preventor. The water system control device and flow meter are thus incorporated within one housing.  
           [0009]    The positive flow meter is integrated in a water control system valve or backflow preventor that include a main chamber and a bypass channel. A movable indicator is disposed within the bypass channel and a position sensor is located near the bypass channel so that the position of the movable indicator is detectable via the sensor. The flow meter may further be integrated with a backflow preventor having a flow resisting element and a position sensor located near the flow resisting element so that a position of the flow resisting element may be detected to provide a measure of flow in the forward direction. A combination of sensors may be used on the flow resisting element and the bypass channel indicator to provide a high flow/low flow indication.  
           [0010]    The foregoing and other objectives, features, and advantages of the invention will be apparent from the following, more particular, description of the preferred embodiment of the invention, as illustrated in the accompanying drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a mechanical drawing depicting a cross-section of an electrically operable valve assembly incorporating a flow meter in accordance with an embodiment of the invention.  
         [0012]    [0012]FIG. 2 is a mechanical drawing depicting a top view of the electrically operable valve assembly of FIG. 1.  
         [0013]    [0013]FIG. 3 is a mechanical drawing depicting a cross-section of an electrically operable valve assembly incorporating a flow meter in accordance with an alternative embodiment of the invention.  
         [0014]    [0014]FIG. 4 is a mechanical drawing depicting a cross-section of a backflow preventer incorporating a flow meter in accordance with an alternative embodiment of the invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0015]    1. Electrically Operable Valve  
         [0016]    Referring now to the figures and in particular to FIG. 1, an electrically operable valve assembly  10  in accordance with an embodiment of the present invention is depicted. A water supply inlet  11  provides a connection to a water supply system such as a city water main connection. A household water supply outlet  12  provides connection to a household water supply system. In the depicted embodiment, electrically operable valve assembly  10  includes a backflow preventor, which prevents any backflow of water to the water supply. The backflow preventor comprises a piston  30  and spring  31  that prevent the flow of water when back water pressure moves piston  30  to compress spring  31 . Alternatively a ball  30 A may be used in place of piston  30 , with the ball mounted above spring  31 . Alternatively, as shown in balloon  40 , a ball  30 B may be used in place of piston  30 , with the ball mounted above a spring  31 A. The backflow preventor device is closely coupled to the operation of an integral flow meter, which will be described in further detail below. The backflow preventor device is closely coupled to the operation of an integral flow meter, which will be described in further detail below.  
         [0017]    Control of electrically operable valve assembly  10  is provided by a piston-mounted gasket assembly  20  that shuts off the main water channel from water supply inlet  11  to household water supply outlet  12 . Gasket assembly  20  is slidably mounted on an outer piston  23  that surrounds an inner piston  22 . Outer piston  23  is mechanically coupled to a lower diaphram  16 . Electrically operable valve assembly is closed by water pressure on the lower side of lower diaphram  16  causing outer piston  23  to move gasket assembly  20  to force the gasket against seat  21 . The water pressure on the lower side of lower diaphram  16  is supplied by a channel  15  that receives flow when a piston  14  coupled to electrical solenoid  13  is in the raised position. Referring momentarily to FIG. 2, channel  15  receives flow from central aperture  51  which in turn receives flow from peripheral aperture  55  when piston  14  is raised (an o-ring or washer is provided at the end of piston  14  to provide a seal). Peripheral aperture  55  is coupled to water supply inlet  11  and thus provides a source of pressure higher than household water supply outlet  12 .  
         [0018]    Since the only path to the lower side of lower diaphram  16  is provided through channel  15 , when piston  14  is lowered, water pressure must be relieved through channel  15  to open electrically operable valve  10 . Piston  14  is hollow, and provides a connection from channel  15  (via central aperture  51  of FIG. 2) to a side port channel  24  that extends around the diaphram assemblies and connects to an exit channel  26  on the outlet side  12  of electrically operable valve  10 . Referring to FIG. 2, the path of channel  24  connects through channels  54  and  56  to channel  17  and venturi  18  of FIG. 1. Flow in the main channel of electrically operable valve  10  causes a reduced pressure at venturi  18 , pulling water through the above-described path from the top side of lower diaphram  16  as the valve closes. A stop ball  53  disposed within channel  54  prevents backflow through this path.  
         [0019]    Solenoid  13  may be a latching-type solenoid, permitting a momentary pulse to operate electrically operable valve assembly  10 . A latching solenoid is preferred for extending solenoid life and for reducing power consumption and noise, but a standard solenoid may be preferred if it is desirable to cut-off water flow when electrical supply to the assembly fails.  
         [0020]    2. Pressure Regulator  
         [0021]    Upper diaphram  25  provides a pressure regulator integrated within electrically operable valve assembly  10 . A channel  17  connects to a venturi  18  that couples the household water outlet side  12  of electrically operable valve assembly  10  to the lower side of upper diaphram  25 . The pressure supplied through channel  17  to upper diaphram  25  acts against spring  27  that is manually adjustable via turnscrew  28 . When the outlet pressure exceeds a level as set by turnscrew  28  adjustment, upper diaphram  25  lifts inner piston  22 , raising gasket assembly  20 , restricting the flow through the main channel of electrically operable valve assembly  10 . Thus, a pressure feedback mechanism is established that regulates the pressure at outlet  12 .  
         [0022]    3. Flow Meter  
         [0023]    A flow meter may be implemented within electrically operable valve assembly  10  by a sensor  35  mounted near bypass channel  32  inlet. A ball  34  is mounted within bypass channel  32  and may be made of a magnetized material or ferromagnetic material for use with a hall effect sensor. Sensor  35  may be a hall effect sensor, inductive sensor or other suitable sensor for detecting the proximity of ball  34 . The output indication from sensor  35  may be a continuous analog reading of the position of ball  34 , or a binary flow/no-flow indication.  
         [0024]    The flow meter implemented by ball  34  and sensor  35  is a positive flow meter in that any flow through valve assembly  10  will move ball  34  away from sensor  35 , providing measurement of flows much lower than flow rates detectable with conventional flow meters for household water supply applications, which typically cannot detect flows below 0.5 gallons per minute. The positive flow meter permits detection of low volume water leaks that may cause damage to a structure without registering a flow at a flow meter detection system. Since any flow through valve assembly  10  requires a pressure drop between water supply inlet  11  and household water supply outlet  12 , ball  34  will move away from sensor  35  as flow through bypass channel  32 . Spring  33  has a very low spring constant and very little force on ball  34  is required to compress spring  33 . When no flow (or back flow begins to occur), ball  34  will be forced by spring  33  against seat  36 , effectively closing bypass channel  32  to prevent backflow leakage. Setscrew  37  permits adjustment of the cross-section of bypass channel  32 , providing a means for adjusting the sensitivity of the flow meter at the factory or after installation. As the channel cross-section decreases, the amount of force compressing spring  33  for a given flow rate will increase, thus increasing the sensitivity of the flow meter.  
         [0025]    Spring  31  is designed so that gasket assembly  30  will not open the main valve channel until the sensor  35  detects positive flow and therefore any flow through electrically operable valve assembly  10  will result in an indication from sensor  35 . The above operation is accomplished by making the spring constant of spring  31  such that ball  34  will travel past sensor  35  before spring  31  is compressed to open the main valve channel.  
         [0026]    4. Alternative Electrically Operable Valve and Flow Meter 1  
         [0027]    Referring now to FIG. 3, an electrically operable valve and flow meter in accordance with an alternative embodiment of the invention is depicted. In this embodiment, the pressure regulator is removed from the embodiment depicted in FIGS. 1 and 2, simplifying the structure of the assembly. In the depiction, like reference numbers are used to indicate the corresponding components, the operation of which is described above for the embodiment of FIGS. 1 and 2. Therefore, only differences between the assemblies will be described.  
         [0028]    Piston  23 A is a single sleeve piston operating in similar fashion to outer piston  23  of FIG. 1. Piston  23 A does not have to be hollow, as inner piston  22  of FIG. 1 was provided to implement pressure regulation and is therefore not needed in the present embodiment. Piston  23 A is slidably coupled to gasket assembly  30 A, which is operated by diaphram  16  or backpressure from water supply outlet  12 , eliminating the need for the separate gasket assemblies  30  and  20  of FIG. 1. The sliding mount of gasket assembly  30 A in conjunction with spring  31  provides closure of the main channel at the onset of flow until ball  34  has seated against seat  36 , providing proper operation of the flow meter within the bypass channel. However, since forward pressure can be applied through channel  32  when the valve is closed (channel  32  in the embodiment of FIG. 1 is effectively closed by gasket assembly  20  when the valve is closed), a second seat  36 B is provided for ball  34  in the reverse flow direction, preventing leakage through the flow meter channel  32  when the valve is closed. The bottom of seat  36 B is provided by a threaded insert  43  in the depicted embodiment. In order for ball  34  to move when a forward flow is generated through the valve assembly, water must flow channel  32 . Forward flow is provided by a channel passing through threaded insert  43 . Balloon detail  42  depicts the above-described channel  38  that is cross-drilled through threaded insert  43  to connect with the hole that is drilled to retain spring  33 . When the valve is closed, water can flow through channel  38  from the center of spring  33 , until ball  34  seats at bottom seat  36 B.  
         [0029]    5. Alternative Embodiment—Backflow preventor with Flow Meter  
         [0030]    Referring now to FIG. 4, a backflow preventor  70  in accordance with an alternative embodiment of the invention is depicted. Backflow preventer includes a water supply inlet  72  and a water supply outlet  71  for coupling the backflow preventer to an electrically operable valve for control of a household water supply. a plunger  74  is slidably mounted on a piston assembly  73  which includes vanes  72  that permit the passage of water beyond piston assembly  73 . A spring  75  pushes plunger  74  against a seat, preventing flow of water from water supply outlet  71  to water supply inlet  72 . Flow from water supply inlet  72  to water supply outlet  71  compresses spring  75  and spring  75  can be designed to provide pressure reduction from water supply inlet  72  to water supply outlet  71  if desirable for a particular application.  
         [0031]    A flow meter is integrated within backflow preventor  70  by a ball  81  and sensor  85  which operate and are constructed as described above for the flow meter incorporated within the electrically operable valve asembly  10  of FIG. 1. Spring  82  is compressed by flow through channel  80  and the spring constant of spring  82  is specified so that ball  81  will move away from sensor  85  at a flow rate lower than that required to move plunger  74 . A seat  83  prevents backflow through channel  80  and a setscrew  84  provides adjustment of the cross section of bypass channel  80 , permitting adjustment of the flow meter sensitivity. A second flow meter may be incorporated within backflow preventer  70  by incorporating a movable indicator  76  on the end of plunger  74  and detecting the position of movable indicator  76  with a second sensor  77 . Since ball  81  will move at flow rates lower than those required to move moveable indicator  76 , sensor  77  is a “high flow” indicator with respect to sensor  85 , which may provide a failure indication if sensor  85  is inactive when sensor  77  provides an indication of flow. Or, sensor  85  and sensor  77  may be used within a household water control system to provide indication of various levels of flow. For example, a dripping faucet will activate sensor  85 , but will probably not activate sensor  77 , while a major plumbing leak will activate both.  
         [0032]    The embodiments of the invention described above disclose an electrically operable valve with pressure regulation incorporated within one housing and using common mechanisms between the valve and pressure regulator. In the alternative embodiment, backflow prevention and flow rate indication are corporated also within a common housing. Both embodiments provide a flow meter capable of registering very low flow rates, so that household leak detection may be accomplished for very low flow rate leaks. The valve is suitable for use within the system and method described in the above-incorporated patent application “METHOD AND SYSTEM FOR CONTROLLING A HOUSEHOLD WATER SUPPLY”, wherein the valve will provide a compact solution having very high sensitivity to water supply system leaks.  
         [0033]    While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form, and details may be made therein without departing from the spirit and scope of the invention.