Abstract:
A flow rate meter that includes a container of known and fixed volume. Electrodes, or sensors, are placed inside the container at several different heights. An electronic circuit uses the electrodes, or sensors, to measure the time it takes this container of known and fixed volume to fill a certain distance with water or water-based solution. The electronic circuit calculates the flow rate in engineering units from this elapsed time by knowing the volume of the container between the fixed electrodes.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
       [0001]    This patent application claims the benefit of U.S. Provisional Patent Application No. 61/210,304, filed Mar. 17, 2009, the entire teachings and disclosure of which are incorporated herein by reference thereto. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention generally relates to measuring devices, and, more specifically, to devices used for measuring liquid flow rates. 
       BACKGROUND OF THE INVENTION 
       [0003]    Conventional flow rate measurement and calibration systems have required the water or water-based solution to discharge directly into the flow meter, pass through the flow meter, then empty into open atmosphere. This conventional method of flow rate measurement adds back pressure to the point of discharge at the nozzle, faucet, showerhead, pump, sprinkler head, pipe, or irrigation nozzle and, therefore, may adversely affect the accuracy of the measurement by altering the true flow rate, which is desired to be measured. 
         [0004]    Conventional practices for measuring flow rate into an open atmosphere involves catching the flow in a calibrated volumetric container for a specified period of time, which is often measured with a stopwatch. Modern agricultural sprayers can have greater than 50 nozzles on a boom. Typically, this method involves the user holding a graduated pail under the nozzle being tested and using a stop watch to mark out one minute so the flow rate could be read from the pail graduations. This process requires two hands and can be quite time consuming if, for example, the flow rate from each nozzle of a 50-nozzle spraying system is being tested. 
         [0005]    It would therefore be desirable to have an apparatus for accurately determining the flow rate of a liquid at the point of discharge that does not create back pressure at the point of discharge. It would also be desirable if the apparatus could provide flow rate data more quickly than conventional flow rate measurement systems without the use of a stopwatch. The invention provides such a flow rate measurement apparatus. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    In one aspect, embodiments of the invention provide a flow rate meter that includes a constant-volume container with an attached electronic circuit and display. In at least one embodiment, sensors placed inside the constant-volume container measure the elapsed time during filling, which is a function of the liquid flow rate into the container. The electronic circuit senses this filling event and then calculates and displays a flow rate on the display. 
         [0007]    In another aspect, embodiments of the invention provide a flow rate meter that includes a container with a closed end and an open end, and a measuring apparatus attached to the container. In an embodiment of the invention, the measuring apparatus has a first electrode configured to be inserted through a wall of the container such that the first electrode is suspended inside the container at a first distance from the closed end. This embodiment further includes a second electrode configured to be inserted through the wall of the container such that the second electrode is suspended inside the container at a second distance from the closed end, the second distance being greater than the first distance. Further, the measuring apparatus is configured to determine a flow rate based on the amount of time needed for a liquid level to rise from the first electrode to the second electrode. 
         [0008]    In yet another aspect, embodiments of the invention provide a method of manufacturing a flow rate measurement system that includes the steps of providing a container having an open end and a closed end, and affixing a measuring device to the container. In an embodiment, the measuring device includes a plurality of electrodes inserted into the container through a wall thereof. In this embodiment, the method further includes calibrating the measuring device, based on a volume of the container, to calculate a flow rate. In this embodiment, the flow rate is determined by the time it takes for liquid flowing into the open end of the container to rise from a first electrode of the plurality of electrodes to a second electrode of the plurality of electrodes. 
         [0009]    Other aspects, objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings: 
           [0011]      FIG. 1  is a perspective view of a flow rate meter, constructed in accordance with an embodiment of the invention; 
           [0012]      FIG. 2  is a top view of the flow rate meter of  FIG. 1 ; 
           [0013]      FIG. 3  is a front view of the flow rate meter of  FIG. 1 ; 
           [0014]      FIG. 4  is a cross-sectional view of the flow rate meter of  FIG. 1 ; and 
           [0015]      FIG. 5  is a block diagram of an electronic circuit configured to be incorporated into the flow rate meter of  FIG. 1 . 
       
    
    
       [0016]    While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    A flow rate meter  100 , constructed in accordance with an embodiment of the invention, is shown in  FIGS. 1-4 . The flow rate meter includes a hollow container  10  and an electronic circuit  60  placed on circuit board  30  contained in sealed housing  20 . In an embodiment of the invention, the flow rate meter  100  is held in an upright position as shown in  FIG. 1 . End cap  40  covers a compartment  41  in the lower end of hollow container  10 , which contains batteries  34  for powering the electronic circuit  60  on circuit board  30 . In an embodiment, the sealed housing  20  is mounted to the outside of hollow container  10  such that electrodes  31 ,  32  and  33  protrude into an inner hollow portion of hollow container  10 . In some embodiments, the sealed housing is configured to be removable from the hollow container so that the electronics in the sealed housing  20  can be serviced or replaced as necessary. The top end of hollow container  10  is open to allow water or water-based solutions to enter the hollow container  10  during operation. The bottom end  11  of hollow container  10  is closed so that water or water-based solutions that enter the top of the hollow container  10  during use are retained fully inside. 
         [0018]    In at least one embodiment of the invention, a control button  22  is pressed by the user to ready a microcontroller  35  for a measurement. The user then directs the flow of water or water-based solution fully into the top of hollow container  10 . This flow causes hollow container  10  to start filling. As the fill progresses, the level of fluid is detected by electrodes  31 ,  32  and  33 . The fill time between electrode  32  and  33  is recorded by the microcontroller  35 . The microcontroller  35  then performs a calculation based on this fill time and the volume of the hollow container  10  between electrodes  32  and  33  to determine the flow rate of liquid entering the hollow container  10 . Once the fill level has reached electrode  33  and a reading has been displayed on display  21  by microcontroller  35 , then hollow container  10  can be emptied of its fluid contents by tipping the hollow container  10  upside down, thus allowing contained fluid to empty out from the open top of hollow container  10 . 
         [0019]    Referring now to the invention in more detail,  FIGS. 2 and 3  show a hollow container  10 , which, in this particular embodiment, is comprised of a circular tube, or other suitable container, such that it is open on the top and closed on the bottom  11 . In at least one embodiment, hollow container  10  is formed or molded from clear or opaque plastic. In alternate embodiments hollow container  10  is formed from metal or glass. The material used to construct the hollow container  10  should be a rigid material, such that the volume of the container is constant and does not change during use, or between uses. 
         [0020]    Now referring to  FIG. 1  and  FIG. 4  in more detail, in an embodiment of the invention, sealed housing  20  is comprised of a molded or fabricated plastic or metal enclosure to completely encase circuit board  30  and provides a means of protecting said circuit board  30  from dust, moisture, and physical damage. In a preferred embodiment, sealed housing  20  is made from molded plastic which fully encapsulates circuit board  30 . In the embodiment shown, sealed housing  20  is positioned and attached to hollow container  10  such that electrodes  31 ,  32 , and  33  projecting from circuit board  30  are placed inside hollow container  10 .  FIGS. 2 and 4  provide an exemplary illustration of electrodes  31 ,  32 , and  33  projecting into the center of hollow container  10 . 
         [0021]    Referring to  FIG. 4 , circuit board  30  is shown embedded in sealed housing  20  with display  21  and start button  22  attached directly to the circuit board  30 . Electrodes  31 ,  32 , and  33  are also attached directly to circuit board  30 . In the embodiment shown, with respect to electrodes  32  and  33 , the sealed housing  20  extends and covers the majority of the electrodes&#39;  32 ,  33  length  25 ,  26 , such that only a small conductive portions  37 ,  38  of their length are exposed metal. In an embodiment of the invention, those small conductive portions  37 ,  38  are positioned towards the center of an interior portion of the hollow container  10 . Placement of the conductive portions  37 ,  38  of these electrodes  32 ,  33  substantially at the center of an interior portion of hollow container  10  allows tilting of the container  10  from the vertical axis without causing a change in the sensed level of fluid due to their central location and the circular cross-section of hollow container  10 . This is accomplished because as hollow container  10  is tilted the center point of the fluid surface does not change elevation while the outer levels of the fluid surface will vary greatly as the angle of the tube is changed. Locating electrodes  32 ,  33  in the center of hollow container  10  also keeps fluid that is coating and/or running down the inside wall of the hollow container  10  from falsely triggering the electrodes  32 ,  33 . In an embodiment of the invention, the lowest electrode  31  is a reference electrode. In the embodiment shown, the lowest electrode  31  is made of entirely exposed metal. Exposing more metallic surface area helps to increase the strength of signals between electrode  31  and electrodes  32 ,  33  due to the greater conductivity of the lowest electrode  31 . 
         [0022]    In at least one embodiment, electrode  32  is placed some distance above the bottom  11  of the hollow container  10 . This arrangement provides for accurate and repeatable readings since it allows time for the flow of fluid to stabilize as the hollow container  10  is placed under the flow discharge to be tested. Because the hollow container  10  cannot be instantly placed under the full flow discharge, some time is required to bring the flow discharge pattern inside the hollow container  10  to the point that the flow from the discharge is fully contained within the hollow container  10 . Also, the initial flow of fluid down into the bottom of the hollow container  10  causes turbulence that could cause false triggering on electrode  32  if it were placed too close to the bottom  11  of hollow container  10 . 
         [0023]    Still referring to  FIG. 4 , a diffuser pad  50  is placed in the upper end of hollow container  10  to keep spraying or splashing water or water-based solutions from filling the hollow container  10  in a disorderly way and thus to direct liquid spray away from the center of the hollow container. This acts to keep the liquid spray from directly hitting the electrodes  32 ,  33  or the surface of the gathering fluid in hollow container  10 . This helps control the direction of flow of water or water-based solution during filling and allows the flow rate meter  100  to give accurate and repeatable results. In an embodiment of the invention, the diffuser pad  50  may be constructed of metallic or non metallic material such that water may pass through, but with no direct flow path from its top side to its bottom side. In alternate embodiments, the diffuser pad  50  may be constructed of layers of perforated material, cloth, wire mesh, or other loose fibrous material. In at least one embodiment, the diffuser pad  50  is comprised of a non-woven nylon fiber bed. Such a material allows liquid to flow freely through but does not allow direct spray to pass through. In operation, the liquid spray hits the diffuser pad  50  as a hard spray on its top side and then passes through as a gentle flow down the inside of the hollow container  10  as it exits the bottom side of diffuser pad  50 . In this manner, the diffuser pad  50  helps keep the rising fluid level in the hollow container  10  free of turbulence so that electrode or sensor contact is consistent and, thus, accurately represents the true liquid level. In at least one embodiment diffuser pad  50  is supported by support rods  42 . Support rods  42  keep the force of spraying liquid from forcing diffuser pad  50  into hollow container  10  during use. 
         [0024]      FIG. 5  is a block diagram of an electronic circuit  60  configured to be employed in the flow rate meter  100 . In this embodiment, the electronic circuit  60  includes the battery  34 , microcontroller  35 , control button  22 , display  21 , and electrodes  31 ,  32 , and  33 . In an embodiment of the invention, circuit board  30 , as shown in  FIG. 4 , includes the electronic circuit  60 . Battery  34  provides power to microcontroller  35 , which senses conductivity between electrodes  31  and  32  or  33 , and displays calculated flow readings on display  21 . Water or water-based solutions are conductive and allow current to flow between electrode  31  and either electrode  32  or  33 . Microcontroller  35  checks first for conductivity between electrode  31  and  32  to sense when fluid level has reached electrode  32 . When the fluid level reaches electrode  32 , then microcontroller  35  will start checking for conductivity between electrode  31  and  33  to sense when the fluid level reaches electrode  33 . 
         [0025]    Microcontroller  35  measures the time difference between when the fluid level reached electrode  32  and electrode  33 , and then calculates the flow rate of liquid into hollow container  10 . The volume of hollow container  10  is known and fixed between the separation distance of electrodes  32  and  33 . Control button  22  allows the user to place the microcontroller  35  into different operational modes including, but not limited to, “turn on,” “shut off,” “change displayed measurement units,” and “begin a reading sequence.” Display  21  may be an LCD or LED, or other suitable type of display. In a preferred embodiment, display  21  is an LCD display, which facilitates low power draw on battery  34 . Electrodes  31 ,  32  and  33  are of a conductive material. In at least one embodiment, electrodes  31 ,  32 , and  33  are made of stainless steel, which is corrosion resistant, conductive, and may be soldered directly to circuit board  30  with proper chemical flux. 
         [0026]    As described herein, the flow rate meter  100  does not apply back pressure during the measurement process, because the water or water-based liquid discharges through the nozzle, faucet, showerhead, pump, sprinkler head, pipe, or irrigation nozzle into the atmosphere and then into the hollow container  10  of the flow rate meter  100 . The flow rate meter  100  accomplishes this function with a measuring device that has no moving parts and is configured to sense the fluid level internally using electrodes that can detect changes in conductivity. Further, the addition of a diffuser pad controls and manages the flow of liquid into the hollow container  10  to limit the velocity and turbulence of the entering liquid. A further feature of the flow rate meter  100  is its ability to tolerate tilting or movement of the hollow container  10  during a reading due to the centrally located electrodes  32 ,  33 . The use of an open-top container allows for the rapid filling and emptying of liquid during operational use. A further feature of flow rate meter  100  is the direct attachment of the electronic circuit  60  and display  21  to the measuring container  10  so that the flow rate meter  100  may all be carried as a single object. The flow rate meter  100  therefore has no moving parts, and its accuracy is stable over time. In at least one embodiment, the electronic circuit  60  is powered by batteries  34  and displays flow rate on a display  21 . 
         [0027]    By integrating a constant volume container with an electronic circuit that measures the time required for filling a known volume and automatically calculates and displays the flow rate in engineering units, the flow rate meter  100  may, for example, be used to quickly and accurately check the flow rate output from a single spray nozzle, or from multiple spray nozzles. The flow rate meter  100  measures and reports flow rate electronically in gallons, fluid ounces, or liters per minute or other suitable units. The flow rate meter  100  may therefore provide quick and accurate assessment of nozzle flow rate allowing a user to quickly check all nozzles on a spray boom to determine if the nozzles are functioning as expected. The flow rate meter  100  can accomplish the same task with reading times, for example, of around 10-15 seconds per nozzle versus the 75-90 seconds that is common for conventional flow rate measurement systems. One of ordinary skill in the art will recognize that checking flow rates for agricultural spray nozzles is only one possible use for the flow rate meter  100 . It is contemplated that the flow rate meter  100  may also be used to provide flow rate measurements for faucets, pumps, showerheads, sprinkler heads, water pipes, etc. 
         [0028]    All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. 
         [0029]    The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
         [0030]    Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.