Abstract:
An system and method for flow control by controlling the output pressure for a liquid or a gas independently of the input pressure.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority from provisional application No. 61/314,740. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not Applicable 
       DESCRIPTION OF ATTACHED APPENDIX 
       [0003]    Not Applicable 
       BACKGROUND OF THE DESCRIBED EMBODIMENT OF THE PRESENT INVENTION 
       [0004]    The described embodiment of the present invention relates generally to the field of flow controllers. 
         [0005]    In many disciplines, a pressurized fluid or gas must be supplied in precise quantities. Typically, the flow of liquid, fluid or gas, or the quantity of liquid, fluid or gas supplied is controlled by regulating the flow of the fluid or gas. Fluid flow in the invention is independent of conduit size, supply pressure, and the like, and controlling the flow rate ensures that a precise quantity of the fluid is delivered where required. One example of a situation in which the quantity of a fluid supplied should be controlled is the delivery of fluids in an irrigation system. 
         [0006]    Currently there is a great need for farmers, irrigation systems and process flow manufacturers to have an inexpensive, reliable way to have a steady pressure output coming from a variable pressure input. 
         [0007]    The described embodiment of the present invention is of particular significance when used to control the flow of liquids or gases at relatively high flow rates and will be described in detail below in that context. But the described embodiment of the present invention may have application to other fluids or gases and to relatively small flow rates. The scope of the present invention should thus be determined with reference to the claims appended hereto and not the following detailed description. 
         [0008]    A primary impediment to maintaining a constant flow of fluid in a system is that the pressure at which the fluid is supplied may be unknown or variable. In the context of an irrigation system, the source of the pressurized fluid may be a pump. The pressure of the fluid supplied by irrigation pumps can therefore fluctuate significantly. 
         [0009]    The need thus exists for systems and methods for supplying gases and fluids, at a substantially constant flow rate when the input rate may be variable. 
         [0010]    U.S. Pat. No. 4,015,626 issued to the present Applicant discloses a valve assembly for maintaining constant flow rates. This valve assembly comprises a housing that defines upstream and downstream chambers, a movable wall assembly arranged between these chambers, a spring located in the downstream chamber that acts on the movable wall, a bicycle valve located in the upstream chamber such that its control stem engages the movable wall, and coiled high resistance tubing connected between the chambers. Changes in the pressure in the downstream chamber allow the movable wall to move and operate the bicycle valve control stem to open or close the bicycle valve to control the flow of fluid flowing through the valve assembly. The spring may be adjusted to obtain different flow rates. The tubing functions as a pressure reducing restriction and to average the flow rate of fluid passing therethrough. 
         [0011]    U.S. Pat. No. 6,026,849 also issued to the Applicant discloses a flow regulator having first and second stages of regulation. The first stage is a pressure regulation stage that maintains the pressure within an intermediate chamber within a predetermined range above the pressure in an outlet port. The second stage maintains the flow rate within a predetermined range about a target flow rate. Both stages sample the pressure in the outlet port and automatically adjust the flow of fluid to ensure that fluctuations in pressure at the inlet and outlet ports do not affect the flow rate. The flow rate is set and controlled by a piston and valve arrangement The pressure is regulated by a similar piston and valve arrangement. A flexible membrane is used to allow pressures in one chamber to be transferred into a control signal that operates a control valve in another chamber. 
         [0012]    The valve assemblies disclosed in the &#39; 626  and &#39; 849  patents are optimized to regulate the flow of relatively small quantities of gasses and not relatively large quantities of liquids. 
         [0013]    Current systems can only provide stable output pressures if the input pressures are within fairly narrow parameter changes. 
       BRIEF SUMMARY OF THE INVENTION 
       [0014]    One object of the described embodiment of the present invention is to allow flow control for liquids and gases irrespective of the input pressure of the liquid or gas. 
         [0015]    Another object of the described embodiment of the present invention is to provide a better way of controlling liquid and gas flows over a wide pressure range. 
         [0016]    Another object of the described embodiment of the present invention is to provide a less expensive article of manufacture to control liquid and gas flows which is less expensive to manufacture than current technology. 
         [0017]    A further object of the described embodiment of the present invention is to save large amounts of water or other liquids in high volume operations such as field irrigation. 
         [0018]    Other objects and advantages of the described embodiment of the present invention will become apparent from the following descriptions, taken in connection with the accompanying drawings, wherein, by way of illustration and example, one possible embodiment of the present invention is disclosed. 
     
    
     
       BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS 
         [0019]    The drawings constitute a part of this specification and include exemplary embodiments to the described embodiment of the present invention, which may be embodied in various forms. It is to be understood that in some instances various aspects of the described embodiment of the present invention may be shown exaggerated or enlarged to facilitate an understanding of the invention. 
           [0020]      FIG. 1  is an elevation, cutaway view of an example flow control system of a described embodiment of the present invention in a first configuration which is open all the way; 
           [0021]      FIG. 2  is an elevation, cutaway view of the example flow control system of  FIG. 1  in a second configuration when it is opened midway; 
           [0022]      FIG. 3  is an elevation, cutaway view of the example flow control system of  FIG. 1  in a third configuration when it is closed as far as it can be closed; and 
           [0023]      FIG. 4  is a block diagram illustrating an irrigation system incorporating a flow control system as depicted in  FIGS. 1-3 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    Detailed descriptions of described embodiment of the present invention are provided herein. It is to be understood, however, that the present described embodiment of the invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure or manner. 
         [0025]    In accordance with the described embodiment of the present invention,  FIG. 1  shows a cross-sectional view of the invention, showing generally the hollow main housing, the hollow main housing forming a vertical circular opening through the center of the main housing, an input port connected opening into the hollow of the main housing a limited inlet opening between the input port and the hollow main housing, and an output port connected to the opening into the hollow of the main housing. A lesser volume piston adjacent to the limited inlet opening is positioned such that vertical movement of the lesser volume piston will increase or decrease the amount of the flow of fluid which can flow into the hollow main housing through the input opening. The lesser volume piston anchored to the top of a return spring and has a water tight rolling first diaphragm anchored at a vertical location between the constant pressure spring and the lesser volume piston. This rolling first diaphragm is connected to the interior of the hollow main housing around the entire circumference of the interior of the housing below the level of the lesser volume piston. An adjustable control spring connected to a similar rolling second diaphragm is at the opposite end and the interior of the hollow main housing. A this other end a variable pressure spring (control spring) attached to the top of the hollow main housing inside the vertical circular opening is attached to the bottom return spring so that the return force of the spring assists movement. This return force assists movement of the valve member in the first direction. The control spring engages the connecting member to resiliently oppose movement of the valve member in the first direction along the system axis. The position of the piston determines the amount of fluid which can be flowing through the controller at any particular moment of time. Changes in the input pressure move the piston so that the output pressure remains constant over a wide range of input pressures. 
         [0026]    Non-comprehensive examples of additional possible embodiments could include: 
         [0027]    a threaded adjustment screw or pin (hereafter “pin”) attached to the top of the upper second spring (“variable pressure spring” or “control” spring); 
         [0028]    a pressure output adjustment knob on top of the threaded adjustment screw or pin; 
         [0029]    a thread assembly in the top of the hollow main housing for a variable pressure adjustment screw threaded through the thread assembly; 
         [0030]    a spring attachment means to connect the control and return springs; 
         [0031]    a top assembly cap; 
         [0032]    an Input connection fitting; 
         [0033]    an input pressure gauge; 
         [0034]    an output pressure gauge; 
         [0035]    an output connection fitting; 
         [0036]    an upper housing element; 
         [0037]    a lower housing element with a piston sealing means to make the upper piston water-tight; 
         [0038]    a piston sealing means to make the lower piston water-tight; 
         [0039]    assembly screws; 
         [0040]    washers; 
         [0041]    a spring attachment means which is pivotable; and/or 
         [0042]    a gasket on the washers. 
         [0043]    a plurality of smaller springs connected by a connecting means to create one large spring for the top or bottom spring, and/or one could also use two small springs connected by a connecting means to create one large spring for the top or bottom spring. 
         [0044]    Referring initially to  FIG. 1  of the drawing, depicted therein is an example of a completely open flow controller  20  constructed in accordance with, and embodying the principals of the present invention. The flow controller  20  comprises a housing assembly  30 , a first diaphragm  32 , and a second diaphragm  34 . The housing assembly  30  defines a first input housing port  40  and a second output housing port  42 . The first diaphragm  32  and second diaphragm  34  are supported relative to the housing assembly  30  such that the housing assembly  30  and the first diaphragm  32  and the second diaphragm  34  define a main chamber  44 . The first diaphragm  32  and the second diaphragm  34  are both vented to outside atmospheric pressure. The first diaphragm  32  is vented to outside atmospheric pressure through first filter vent  155 . The second diaphragm  34  is vented to outside atmospheric pressure through a second filter vent  156 . The operative part of the valve assembly is comprised of a piston  48 , which in the preferred embodiment is composed of a strong metal such as brass. It creates a valve in conjunction with its movement across the first valve port  46 . The piston  48  is disposed within the main chamber  44  such that the flow controller  20  defines a flow path that extends through the first housing port  40 , the first valve port  46 , the main chamber  44 , the second valve port  76 , and the second housing port  42 . Fluid flowing along the flow path causes the piston  48  to move relative to the housing assembly  30  such that a cross-sectional area of a portion of the flow path is altered. In the preferred embodiment, a cylindrical enclosure  200  comprised of a brass tubing encircles the first spring  84  (lower spring or return spring) so that the return force assists movement of the piston  48 . Also, the preferred embodiment has a gasket  201  comprised of stainless steel at the base of the piston  48 . 
         [0045]    More specifically, an inlet pressure of the fluid at the first housing port  40  will determine a position of the piston  48  relative to the opening  46  of the input housing port  40 . When the inlet pressure is below a first pressure level, the piston  48  will be in a home position and fully opened as illustrated in  FIG. 1  and the valve will be open all the way. When the inlet pressure is above a second pressure level, the piston  48  will be in an end or closed position as illustrated by  FIG. 3 . The input pressure level is always kept greater than the output pressure level. The output pressure is kept constant by the combined action of the first diaphragm  32  and second diaphragm  34  adjusted by the pressure of a second spring  82  (upper spring or control spring) and a first spring  84  (lower spring or return spring). The upper spring is  82  and the lower spring is  84 . The spring pressure of the second spring  82  (upper spring) and the first spring  84  (lower spring) is adjusted by the adjustment screw or adjustment pin  144 . When the inlet pressure is between the first lower and the second higher pressure levels, the piston  48  will be in an intermediate position between the home position and the end position as shown in  FIG. 2 , thereby keeping the output pressure constant. 
         [0046]    An effective cross-sectional area of the flow path is defined by a spatial relationship between the housing assembly  30  and the piston  48 . When the piston  48  is in the home position and fully open, the first valve port  46  is fully open as it faces the first main port  40  and the effective cross-sectional area of the flow path is at its greatest value. When the piston  48  is in the end position, none of the first valve port  46  is open as it faces the first main port  40  and the effective cross-sectional area of the flow path is at its smallest value. As shown in  FIG. 2 , when the piston  48  is between the home and end positions, a portion of the piston  48  faces the first main port  46 , and the value of the effective cross-sectional area of the flow path is somewhere between the greatest value and the smallest value. The effect of the springs and the diaphragms working in concert is to alter the effective cross-sectional area of the flow path, and the volume of fluid allowed to flow along the flow path over time is increased or decreased thereby keeping the output pressure constant at the desired pressure. 
         [0047]    Accordingly, even if the inlet pressure varies within a range of inlet pressures defined by the first lower and second upper pressure levels, the flow controller  20  can maintain a substantially constant volume of fluid flowing along the flow path. To be most effective, the input and output pressure should be at least 5 psi higher in the input pressure than the output pressure. 
         [0048]    With the foregoing general understanding of the described embodiment of the present invention in mind, the details of operation and construction of the example flow controller  20  will now be described in further detail. 
         [0049]    Referring back to  FIG. 1  of the drawing, the example housing assembly  30  of the flow controller  20  comprises a main housing  52 . In the preferred embodiment, “O” rings may be used to seal a housing made of multiple parts. An inlet member of the main housing  52 , an outlet member of main housing  54 , and a spring member of main housing  56  comprise the main body of the housing  30 . The inlet member of main housing  52  and outlet member of main housing  54  are rigidly connected to the main housing  50  to allow external inlet and outlet conduits (not shown) to be connected to the first and second housing ports  40  and  42 , respectively. The second spring member of main housing  56  is rigidly connected to the main housing  50 . 
         [0050]    The example flow controller  20  further comprises a sleeve  60  and a cap  62 . The sleeve  60  comprises a first sleeve member  64  and a second sleeve member  66 . The sleeve  60  is arranged within the main chamber  44 , and the first diaphragm  32  is supported by the sleeve  60  and the cap  62  within the main chamber  44 . The second spring member of main housing  56  supports the cap  62  such that a spring chamber  68  is defined between the cap  62  and the second spring housing  56 . The second spring member of main housing  56  further holds the cap  62  against the first diaphragm  32 , the first diaphragm  32  against the sleeve  60 , and the sleeve  60  against the main housing  50 . 
         [0051]    A connecting member  70  extends between the piston  48  and the first diaphragm  32  and the second diaphragm  34 . As shown by a comparison of  FIGS. 1 ,  2 , and  3 , the connecting member  70  rigidly connects the piston  48  and the first diaphragm  32  such that the piston  48  and the traveling portion  72  of the first diaphragm  32  and the second diaphragm  34  move together. 
         [0052]    The sleeve  60  defines a first sleeve port  74 , a second sleeve port  75 , and an outer surface  78 . As shown in  FIG. 1 , a channel  80  is formed in the outer surface  78  of the sleeve  60 . The channel  80  is substantially aligned with the first main port  40 . The valve members defined by a first valve port and a second valve port, are arranged within the main chamber such that a flow path extends through the first housing port, the first valve port, the first sleeve port, the second valve port, and the second housing port, and the second sleeve port, causing fluid to flow along the flow path such that the fluid causes the 
         [0053]    valve member to move relative to the sleeve to alter a cross-sectional area of a portion of the flow path 
         [0054]      FIG. 1  further illustrates that the example flow controller  20  comprises an upper second spring  82  and a lower first spring  84 . The upper second spring  82  (control spring) is arranged within the spring chamber  68  and applies a control force to the connecting member  70  and thus to the traveling portion  72  of the first diaphragm  32  and to the piston  48 . The control force opposes movement of the piston  48  in a first direction along a system axis B defined by the housing assembly  30 . The lower first spring  84  is arranged to apply a return force to the piston  48  so that the return force assists movement of the piston  48  in the first direction along the system axis B. 
         [0055]    The upper second spring  82  is supported under compression between a first valve seat member  86  and a second valve seat member  88 . The first valve seat member  86  is supported by the second spring member of main housing  56 . The second valve seat member  88  engages the connecting member  70 . A position of the first valve seat member  86  relative to the second spring member of main housing  56  is adjustable to allow a bias force to be applied to the upper second spring  82  (control spring). The bias force allows the compression on the upper second spring  82  to be adjusted. 
         [0056]    As described above, the effective cross-sectional area of the flow path is smallest when the piston  48  is in the end (closed) position as shown in  FIG. 3 . In particular, the effective cross-sectional area of the flow path is defined by the dimensions of the interstitial space  94 . The interstitial space  94  thus always allows a small amount of fluid flow between the first sleeve port  74  and the first valve port  46 , even when the piston  48  is in the end position. The example flow controller  20  thus never completely shuts off the flow of fluid between the first housing port  40  and the second housing port  42 . 
         [0057]    The first diaphragm  32  is a flexible, fluid impermeable sheet. A perimeter edge of the first diaphragm  32  is rigidly held between the sleeve  60  and the cap  62 . The traveling portion  72  of the first diaphragm  32  is rigidly connected to the connecting member  70 . Accordingly, movement of the traveling portion  72  of the first diaphragm  32  is transferred to the connecting member  70 . During use of the example flow controller  20 , the inlet member of main housing  52  is connected to an inlet conduit (not shown) that is in turn connected to a source of unregulated, pressurized liquid such as an irrigation pump. The outlet member of main housing  54  is connected to an outlet conduit that is in turn connected to a destination of regulated liquid, such as a sprinkler assembly. 
         [0058]    The channel  80  extends completely around the first sleeve member  64  and the openings  92 . Accordingly, fluid flowing through these openings  92  into the interstitial space  94  flows generally radially inwardly toward the system axis B. The fluid in the interstitial space  94  thus does not act asymmetrically on the second diaphragm  34  in a manner that would force the second diaphragm  34  against the sleeve  60  and thereby inhibit movement of the second diaphragm  34  along the system axis A. 
         [0059]    Pressurized liquid within the main chamber  44  acts on the first diaphragm  32 . Above the first pressure level, the force applied by the pressurized liquid on the first diaphragm  32  will displace the traveling portion  72  of the first diaphragm  32  in a first direction indicated by Arrow B in  FIG. 1 . Because the traveling portion  72  is rigidly connected to the connecting member  70  and the connecting member  70  is rigidly connected to the piston  48 , the piston  48  is also displaced in the First Direction B. The second diaphragm  34  does not impede the movement of the piston  48 , because the effective area of the second first  32  is smaller than the effective area of the second diaphragm  34 . 
         [0060]    In the preferred embodiment, the ratio of the effective area is 1.05 to 0.37 between the first diaphragm  32  and the second diaphragm  34 . 
         [0061]    With appropriate selection of the springs  82  and  84  and the bias force applied to the upper second spring  82  (control spring), the piston  48  will reciprocate along the system axis B as necessary to adjust for fluctuations in the inlet pressure. The flow rate of fluid exiting the main chamber  44  through the second sleeve port  75  and the second housing port  42  will thus be maintained at a substantially constant level set by the values of the springs  82  and  84  and magnitude of the bias force. 
         [0062]    The flow controller  20  may also be constructed in one type of embodiment without the control spring  82  and the bias spring  84 . In this case, the first diaphragm  32  itself must be constructed to resiliently oppose pressure established by liquid within the main chamber  44 . For the pressures expected in liquid systems such as an irrigation system, however, use of the springs  82  and  84  greatly simplifies the fabrication of the first diaphragm  32  and second diaphragm  34 . 
         [0063]    The first diaphragm  32  is rigidly connected to the connecting member  70  as follows. In the preferred embodiment example shown, connecting member  70  is a threaded rod having a first end  120  secured to a cross-brace assembly  132  and a second end  124 . Depressions  126  and  128  are formed in the first and second valve seat members  86  and  88 , respectively. The second end  124  of the connecting member  70  is configured to engage the depression  128  formed in the second valve seat member  88 . 
         [0064]    A first nut  130  is threaded onto the connecting member  70 . The threaded member  70  is then inserted through a first diaphragm plate  132  (cross-brace assembly), the traveling portion  72  of the first diaphragm  32 , and through a second first diaphragm plate  134 . A second nut  136  is then threaded onto the connecting member  70  and tightened such that the traveling portion  72  of the first diaphragm  32  is rigidly clamped between the first diaphragm plates  132  and  134 . 
         [0065]    A stop flange  138  extends from the second first diaphragm plate  134 . As shown in  FIG. 3 , when the Piston  48  is in the end position, the stop flange  138  engages the cap  62  to prevent further movement of the first diaphragm  32 . The stop flange  138  thus prevents damage to the first diaphragm  34  under high pressures above the second pressure level.  FIG. 1  further illustrates that the example flow controller  20  further comprises a bias force adjustment assembly  140  comprising an insert  142 , an adjustment screw or pin  144 , and a lock nut  146 . To reduce costs, the spring housing  56  and other components of the controller may be made of plastic or other suitable material. The insert  142  is embedded within the second spring member of main housing  56  to provide an internal threaded surface for engaging the adjustment screw or pin  144 . 
         [0066]    With the adjustment screw or pin  144  (“pin” is defined as either a screw or a pin for purposes of the claims) extending through the second spring member of main housing  56  and threadingly engaged with the insert  142 , axial rotation of the adjustment pin  144  displaces the pin  144  along a longitudinal axis thereof. A first end  148  of the adjustment pin  144  engages the depression  126  formed in the first valve seat member  86 . 
         [0067]    As mentioned above, the housing assembly  30  is typically formed by a number of separate components. These components are secured to each other using a plurality of bolts  150 . Seals  152  in the form of conventional a-rings, gaskets, or the like are used where necessary to establish a fluid-tight fluid path. 
         [0068]    Referring now to  FIG. 4  of the drawing, represented therein is an example irrigation system  220  comprising a water supply  222 , a water distribution system  224 , and a flow control system  226 . The irrigation system  220  is designed to operate within predetermined parameters to distribute water to a particular area to be irrigated. 
         [0069]    The water supply  222  is or may be conventional and provides a source of pressurized water suitable for irrigation purposes. The parameters of the pressurized water supplied by the water supply  222  need not be constant or known in advance; to the contrary, the water pressure can be within an operating range defined by a predetermined minimum determined by the requirements of the water distribution system  224  and a predetermined maximum determined by the components of the flow control system  226 . Often, the water supply  222  takes the form of a pump operatively connected to a reservoir. 
         [0070]    The water distribution system  224  is or may be conventional and typically comprises a set of components, such as conduits, sprinkler assemblies, and/or drip assemblies, configured for the particular area to be irrigated. The water distribution system  224  is typically configured to distribute a predetermined quantity of water during a predetermined time period. The predetermined quantity of water and the predetermined time period will be determined with reference to the characteristics of the area to be irrigated and environmental factors such as heat and/or humidity. 
         [0071]    The example flow control system  226  comprises the flow controller described above. The first housing port  40  is operatively connected to the water supply  222 , while the second housing port  42  is operatively connected to the water distribution system  224 . The flow controller  20  is configured to allow the flow of water from the water supply  222  to the water distribution system  224  to be regulated. Regulation of the flow of water from water supply  222  to the water distribution system  224  allows the quantity of water distributed by the water distribution system  224  over the predetermined time period to be approximately equal to the predetermined quantity of water desired. The flow controller  20  thus helps to ensure that the irrigation system  220  operates within the predetermined operating parameters. 
         [0072]    The flow control system  226  may in one embodiment comprise only the flow controller  20  as described above but may also in other embodiments be configured to include additional components such as an outer housing, pipe fittings, control valves, and the like. The details of the flow control system  226  will thus typically be determined by the details of the water supply  222  and the water distribution system  224 . 
         [0073]    The described embodiment of the present invention may be embodied in forms other than those described above. The scope of the described embodiment of the present invention should thus be determined by the claims appended hereto and not the foregoing detailed description of the invention. 
         [0074]    While the described embodiment of the present invention has been described in connection with a preferred embodiment, it is not intended to limit the scope of the invention to the particular form set forth, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the described embodiment of the present invention as defined by the appended claims. 
         [0075]    Insofar as the description above and the accompanying drawings disclose an additional subject matter that is not within the scope of the single claim below, the inventions are not dedicated to the public and the right to file one or more applications to claim such additional inventions is reserved.