System and method for hydraulically managing fluid pressure downstream from a main valve

Abstract

A system and method for controlling fluid pressure downstream a main valve includes associating a variable orifice with the main valve such that the variable orifice opens as the main valve is opened and closes as the main valve is closed. A fluid stream taken from a fluid inlet of the main valve is passed to an inlet of the variable orifice. A fixed orifice is in fluid communication with an outlet of the variable orifice. A pressure differential between the inlet and outlet of a fixed orifice is detected by a control pilot device, which hydraulically opens or closes the main valve in response to the detected fixed orifice pressure differential between low pressure and high pressure set points.

1 . A method of controlling fluid pressure downstream a main valve, comprising the steps of:
 providing a main valve having a fluid inlet and a fluid outlet, the main valve being configured to open to increase fluid flow therethrough, and close to reduce fluid flow therethrough;   associating a variable orifice with the main valve such that the flow area of the variable orifice changes as the main valve position changes;   passing a fluid stream, having a pressure substantially matching a fluid inlet pressure of the main valve, to an inlet of the variable orifice;   placing an inlet of a fixed orifice in fluid communication with an outlet of the variable orifice;   detecting a pressure differential between the inlet and outlet of the fixed orifice; and   opening or closing the main valve in response to the detected fixed orifice pressure differential.   
   
   
       2 . The method of  claim 1 , wherein the opening or closing the main valve step includes the step of hydraulically opening or closing the main valve. 
   
   
       3 . The method of  claim 1 , including the step of using a control pilot valve apparatus in fluid communication with the variable orifice, the fixed orifice, and the main valve to detect the pressure differential between the inlet and outlet of the fixed orifice and open or close the main valve. 
   
   
       4 . The method of  claim 3 , including the steps of:
 passing a first portion of the fluid stream exiting the outlet of the variable orifice to a first chamber of a low pressure control chamber of the pilot valve apparatus;   passing a second portion of the fluid stream exiting from the outlet of the fixed orifice to a second chamber of the low pressure control chamber of the pilot valve apparatus, the first and second chambers having a first flexible diaphragm therebetween;   generating a second fluid stream having a pressure substantially equal to the fluid inlet pressure of the main valve;   passing a first portion of the second stream to a first chamber of a high pressure chamber of the control pilot valve apparatus at least partially defined by a second flexible diaphragm, through a variable valve, into a second chamber, and outlet of the high pressure chamber;   passing a second portion of the second stream to a hydraulic control chamber of the main valve;   opening or closing the variable valve of the high pressure chamber in response to detected pressures within the high pressure chamber and the low pressure chamber; and   hydraulically opening the main valve by lessening the second portion of the second stream as the variable valve of the high pressure chamber is opened, and   hydraulically closing the main valve by increasing the second portion of the second stream as the variable valve of the high pressure chamber is closed.   
   
   
       5 . The method of  claim 4 , wherein the opening or closing of the variable valve of the pilot valve apparatus includes the step of moving a stem connected to the first flexible diaphragm into contact with a movable poppet of the variable valve. 
   
   
       6 . The method of  claim 1 , including the step of passing the fluid stream through a pressure regulator passageway before passing the fluid stream through the variable orifice. 
   
   
       7 . The method of  claim 6 , including the step of adjusting the pressure regulator passageway in order to modify a downstream flow pressure regulation profile. 
   
   
       8 . The method of  claim 4 , including the step of setting an upper pressure set point and a lower pressure set point. 
   
   
       9 . The method of  claim 8 , wherein the setting of a lower pressure set point step includes the step of selectively limiting a range of travel of the first flexible diaphragm. 
   
   
       10 . The method of  claim 8 , wherein the setting an upper pressure set point step includes the step of selectively limiting a range of travel of the second flexible diaphragm. 
   
   
       11 . A system for hydraulically managing fluid pressure downstream of a main valve, comprising:
 a main valve having a fluid inlet and a fluid outlet, the main valve being configured to open to increase fluid flow therethrough, and to close to reduce fluid flow therethrough;   a variable orifice assembly coupled to the main valve such that the flow area of the variable orifice changes as the main valve position changes;   a fixed orifice in fluid communication with an outlet of the variable orifice; and   a control device operably associated with the main valve, an inlet of the fixed orifice and an outlet of the fixed orifice and configured to detect pressure differentials between the inlet and outlet of the fixed orifice and open and close the main valve in response to the detected pressure differentials.   
   
   
       12 . The system of  claim 11 , wherein the main valve comprises a main valve body defining the fluid inlet and the fluid outlet, a main valve seat disposed between the fluid inlet and the fluid outlet, a main valve member movable between an open position away from the main valve seat and a closed position engaging the main valve seat, and a main valve diaphragm coupled to the main valve member, the main valve diaphragm and the main valve body, or a cover thereof, defining a control chamber. 
   
   
       13 . The system of  claim 12 , wherein the control device is fluidly coupled to the control chamber of the main valve so as to hydraulically open and close the main valve member. 
   
   
       14 . The system of  claim 13 , wherein the control device comprises a control pilot valve apparatus having a high pressure regulating chamber in fluid communication with the inlet of the main valve and the main valve control chamber, and low pressure regulating chambers in fluid communication with the outlet of the variable orifice and the outlet of the fixed orifice. 
   
   
       15 . The system of  claim 14 , wherein the low pressure regulating chambers are separated by a flexible diaphragm supporting an elongated stem. 
   
   
       16 . The system of  claim 14 , wherein the high pressure regulating chamber is at least partially defined by a second flexible diaphragm, and includes a fluid flow passageway. 
   
   
       17 . The system of  claim 16 , including a movable poppet extending from the second flexible diaphragm and into the fluid flow passageway of the high pressure regulating chamber. 
   
   
       18 . The system of  claim 17 , wherein, depending on the pressures within the chambers of the control pilot valve apparatus, the stem is moved into engagement with the poppet, or the second flexible diaphragm moves the poppet to alter the flow through the passageway of the high pressure regulating chamber, resulting in an alteration of hydraulic pressure in the control chamber of the main valve so as to open or close the main valve. 
   
   
       19 . The system of  claim 17 , including an atmospheric chamber disposed between the high and low pressure regulating chambers, the poppet extending into a first end of the atmospheric chamber and the stem extending into a generally opposite end of the atmospheric chamber. 
   
   
       20 . The system of  claim 12 , wherein the variable orifice assembly comprises a housing having a fluid inlet in fluid communication with the main valve inlet, a fluid outlet in fluid communication with the fixed orifice and the control device, and a stem slidably disposed within the housing and coupled to the main valve member. 
   
   
       21 . The system of  claim 20 , wherein the stem and housing cooperatively define the variable orifice between the inlet and the outlet of the housing. 
   
   
       22 . The system of  claim 20 , including a sleeve disposed between the stem and the housing and having an aperture therethrough, the sleeve, stem and housing cooperatively forming the variable orifice. 
   
   
       23 . The system of  claim 22 , wherein the sleeve is adjustably positioned within the housing to vary the fluid flow from the housing inlet to the housing outlet. 
   
   
       24 . The system of  claim 11 , including a pressure regulator apparatus having an inlet fluidly coupled to an inlet of the main valve an inlet and an outlet fluidly coupled to an inlet of the variable orifice assembly, the pressure regulator apparatus having a selectively adjustable fluid passageway disposed between the inlet and outlet thereof. 
   
   
       25 . A control pilot valve apparatus, comprising:
 a housing;   a fluid low pressure regulating chamber disposed within the housing, and divided into first and second sub-chambers, each having a fluid inlet, by a first flexible diaphragm;   a fluid high pressure regulating chamber disposed within the housing, including a fluid passageway intermediate an inlet and an outlet thereof, and at least partially defined by a second flexible diaphragm;   an atmospheric chamber disposed between the fluid low pressure regulating chamber and the fluid high pressure regulating chamber;   a poppet slidably disposed within the atmospheric chamber; and   a stem extending from the first flexible diaphragm into the atmospheric chamber and movable into contact with the poppet;   wherein movement of the poppet by either the stem or the second flexible diaphragm due to fluid pressure variations in the high fluid pressure regulating chamber or the low pressure regulating chamber varies fluid flow between the inlet and the outlet of the fluid high pressure regulating chamber.   
   
   
       26 . The apparatus of  claim 25 , wherein the first flexible diaphragm is selectively biased with a first spring. 
   
   
       27 . The apparatus of  claim 26 , wherein the bias of the first spring is selectively adjustable to limit the movement of the stem to a selected range defining a lower pressure set point. 
   
   
       28 . The apparatus of  claim 25 , wherein the second flexible diaphragm is selectively biased with a second spring. 
   
   
       29 . The apparatus of  claim 28 , wherein the bias of the second spring is selectively adjustable to limit the movement of the poppet to a selected range defining an upper pressure set point.