Abstract:
According to the invention, a constant flow valve along with a three way control valve are arranged so as to provide an enhanced shut-off function. During closure of the flow valve, the pressure of the supply fluid is employed in a manner bolstering the valve&#39;s spring closure force, thereby resisting any tendency of the valve to open in response to fluid supply pressure surges above the valve&#39;s threshold opening level.

Description:
BACKGROUND 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates to fluidic systems employing constant flow valves that are normally closed, that are opened by fluid supply pressures above selected threshold levels, and that when open, serve to deliver fluids at a substantially constant pressure and flow rate. 
         [0003]    2. Description of Related Art 
         [0004]    Constant flow valves of the above-mentioned type are known, as evidenced for example by U.S. Pat. Nos. 6,026,850; 6,209,578; 7,445,021; and 7,617,839, the disclosures of which are herein incorporated by reference. 
         [0005]    With reference to  FIG. 3 , a constant flow valve CFV of the type incorporated into fluidic systems of the present invention comprises a housing  10  having an internal flow path  12  leading from an inlet  14  to an outlet  16  equipped typically with a nozzle  18 . A modulating assembly  20  includes a central hub  22  supported by a flexible diaphragm  24  isolating the flow path  12  from a chamber  26  containing a biasing means which typically may comprise a spring  28 . A pin  30  projects from the central hub  22  through a port  32  in an internal housing wall  34 . The spring  28  serves to resiliently urge the modulating assembly  20  into a normally closed position in which the diaphragm  24  is pressed against a circular shoulder  35  of the housing wall  34  to prevent fluid flow along the flow path  12  from the inlet  14  to the outlet  16 . At inlet fluid pressures above a threshold level, the spring  28  is designed to yield and to accommodate movement of the modulating assembly and its diaphragm away from the circular shoulder  35  to an open position (as depicted in  FIG. 3 ), at which the pin  30  and its enlarged head then coact with the port  32  to control and maintain a substantially constant pressure and flow rate of the fluid flowing along the flow path  12  from the inlet  14  to and out through the nozzle  18  at the outlet  16 . A port  36  is provided at the bottom of the housing for a purpose to be described hereinafter. 
         [0006]    In conventional fluidic systems, one example of which is depicted in  FIGS. 4A and 4B , a shut-off valve V 1  is sometimes employed to control the on-and-off supply of fluid via a supply conduit  38  to a downstream constant flow valve CFV. As discussed above, the constant flow valve is normally closed by the spring  28 , which is designed to yield to fluid supply pressures above a threshold level. At fluid supply pressures above the threshold level, and as depicted in  FIG. 4B , the valve&#39;s modulating assembly  20  operates in its intended controlling mode to supply fluid to a discharge conduit  40  at a substantially constant pressure and flow rate. 
         [0007]    Experience has shown, however, that even when the shut-off valve V 1  is closed, leakage through the constant flow valve CFV may occur if, for whatever reason, the fluid pressure in the supply conduit  38  surges to a level above the constant flow valve&#39;s threshold opening level. Such surges may occur, for example, when the system is being employed to dispense a carbonated liquid beverage component. Between dispensing cycles, the carbonating gas may come out of solution in the liquid trapped in the supply conduit  38  between the shut-off valve V 1  and the constant flow valve CFV, thereby producing a pressure increase of sufficient magnitude to overcome the closure force of spring  28 , causing momentary leakage. 
       SUMMARY OF THE INVENTION 
       [0008]    In accordance with the present invention, the constant flow valve additionally provides a shut-off function. During valve closure, the fluid supply pressure is employed in a manner bolstering the valve&#39;s spring closure force, thereby resisting any tendency of the valve to open in response to fluid supply pressure surges above the valve&#39;s opening threshold level. 
         [0009]    These and other features and attendant advantages of the present invention will now be described in further detail with reference to the accompanying drawings, wherein: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIGS. 1A-1C  are schematic illustrations of a fluidic system in accordance with one illustrative embodiment of the present invention, showing sequential stages of its operation; 
           [0011]      FIGS. 2A-2C  are schematic illustrations of a fluidic system in accordance with a second illustrative embodiment of the present invention, again showing sequential stages of its operation; 
           [0012]      FIG. 3  is an illustration of a known constant flow valve CFV; and 
           [0013]      FIGS. 4A and 4B  are schematic illustrations of a conventional fluidic system susceptible to potential leakage problems. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    With reference to  FIGS. 1A-1C , a fluidic system in accordance with one illustrative embodiment of the present invention is generally depicted at  42 . The system is designed to receive a fluid via a supply conduit  44  at a variable pressure, and to deliver the fluid to atmosphere at a substantially constant pressure and flow rate via a discharge conduit  46 . The system  42  is particularly suited for, although not limited in use to, the delivery of carbonated liquid beverage components. 
         [0015]    The system  42  comprises a constant flow valve CFV of the type illustrated in  FIG. 3 . 
         [0016]    As shown in  FIG. 1A , the spring  28  of the constant flow valve CFV serves to urge the modulating assembly  20  into its normally closed position preventing fluid flow through the valve from the supply conduit  44  to the discharge conduit  46 . 
         [0017]    A second valve V 2 , which may for example comprise a three-way toggle valve of known design, has first, second and third ports P 1 , P 2 , P 3  connected respectively to the chamber  26  of the constant flow valve CFV, the supply conduit  44 , and the discharge conduit  46 . The valve V 2  may either be manually operated, or operated by a solenoid that may be energized remotely. 
         [0018]    In the condition shown in  FIG. 1A , the ports P 1  and P 2  of valve V 2  are open, and port P 3  is closed. A bypass conduit  48  serves to direct pressurized fluid from supply conduit  44  through ports P 2  and P 1  and a connecting conduit  50  into valve chamber  26  via port  36 . The pressurized fluid admitted into chamber  26  serves to bolster the closure force of spring  28 . Thus, in the event of a pressure surge in supply conduit  44 , the same pressure surge will exert an added closure force on the modulating assembly  20 , in effect counterbalancing any tendency of the modulating assembly to be displaced from its closed position, and insuring that the constant flow valve CFV remains shut. 
         [0019]    In order to open the constant flow valve CFV, and as depicted in  FIG. 1B , the valve V 2  is adjusted to close port P 2  and open port P 3  while port P 1  remains open. Fluid pressure in chamber  26  is thus relieved by bleeding fluid through port  36  via connecting conduit  50 , valve ports P 1 , P 3  and a second bypass conduit  52  leading to the discharge conduit  46 . Thereafter, as depicted in  FIG. 1C , movement of the modulating assembly  20  will be accommodated resiliently by spring  28  to control the flow and pressure of the fluid being dispensed to atmosphere via the discharge conduit  46 . 
         [0020]    A fluidic system in accordance with a second illustrative embodiment of the present invention is depicted in  FIGS. 2A-2C . Here, a second constant flow valve CFV 2  is incorporated into the fluidic system of  FIGS. 1A-1C  and serves to supply a controlled flow of a second fluid, which may for example comprise a liquid flavor concentrate to be combined with a carbonated liquid being supplied via constant flow valve CFV. 
         [0021]    The second fluid is supplied to constant flow valve CFV 2  via a second supply conduit  54  from a remote source at variable pressures produced by a pump or the like (not shown). The outlet  16  of constant flow valve CFV 2  is connected by branch conduit  56  to the discharge conduit  46 , and another branch conduit  58  connects the chamber  26  of constant flow valve CFV 2  to the conduit  50 . 
         [0022]    In  FIG. 2A , both constant flow valves CFV and CFV 2  are closed, and closure is assured by the application of fluid pressure from supply conduit  44  to the chamber  26  of constant flow valve CFV via bypass conduit  48 , ports P 2  and P 1  of control valve V 2  and connecting conduit  50 , and to the chamber  26  of constant flow valve CFV 2  via branch conduit  58 . 
         [0023]    As shown in  FIG. 2B , fluid pressure in the chambers  26  of both constant flow valves CFV and CFV 2  is relieved by closing port P 2  of control valve V 2  and opening port P 3  while allowing port P 1  to remain open. This allows fluid to be bled from the chamber  26  of constant flow valve CFV via conduits  50  and  52  to discharge conduit  46 , and from the chamber  26  of constant flow valve CFV 2  via conduits  58 ,  50  and  52  to the discharge conduit  46 . 
         [0024]    Once fluid pressure is relieved in the chambers  26  of both constant flow valves, and as depicted in  FIG. 2C , the constant flow valves then operate in their intended controlling mode to deliver the first and second fluids via the discharge conduit  46  at substantially constant pressures and flow rates. 
         [0025]    It will be seen, therefore, that in each of the above described system embodiments of the present invention the constant flow valves provide a shut-off function in addition to flow and pressure control functions, with valve closures being immune from disturbance by pressure surges in the fluids being supplied to the valves. 
         [0026]    By employing simple and relatively inexpensive control valves, e.g., three way toggle valves or the like, to selectively apply fluid supply pressures to open and close the constant flow valves, the need for more expensive upstream shut-off valves is eliminated, making it possible to reduce overall system costs.