Abstract:
A pressure regulator valve including a valve seat separating a fluid flowpath into an upstream region and a downstream region. A valve closure member is mounted on a valve stem, the valve stem operable to vary a separation between the valve seat and the valve closure member. A diaphragm is mounted in a housing, mobile portions of the diaphragm responding to changes of pressure in the downstream region by changing position relative to the housing. A diaphragm stem is attached to the diaphragm such that movement of the mobile portions of the diaphragm causes movement of the diaphragm stem. A linkage mechanically couples the diaphragm stem to the valve stem. The linkage includes four connected links, the links attached to each other at connection points. The linkage having a mechanical advantage which varies as the positions of the diaphragm stem and valve stem change.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority based on U.S. Provisional Patent Application No. 60/711,313 for “Variable Rate Pressure Regulator” filed Aug. 25, 2005, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     This invention relates to regulator valves, and more particularly to diaphragm type regulator valves. 
     BACKGROUND 
     Diaphragm type regulator valves are used in applications that include, for example, the delivery of natural gas. Such valves can be configured with a spring biasing the diaphragm against resistance provided by pressure in a chamber on the other side of the diaphragm. Fluid connections between the chamber and the downstream side of the regulator valve cause pressure in the chamber to reflect pressure on the downstream side of the regulator valve. Thus, changes in pressure on the downstream side of the regulator valve cause movement of the diaphragm that, through mechanical linkages, can cause valve disc movement. 
     L-shaped levers can be used as part of these mechanical linkages. Such levers can be configured to provide a particular ratio between the amount of diaphragm movement and the amount of valve disc movement. This ratio and the forces applied are constant regardless of whether the valve is opening or closing and regardless of the position of the valve disc. 
     SUMMARY 
     In one aspect of the invention, a pressure regulator valve includes a valve seat separating a valve flowpath into an upstream region and a downstream region. A valve closure member is mounted on a valve stem, the valve stem operable to vary a separation between the valve seat and the valve closure member. A diaphragm is mounted in a housing with mobile portions of the diaphragm responding to changes of pressure in the downstream region by changing position relative to the housing. A diaphragm stem is attached to the diaphragm such that movement of the mobile portions of the diaphragm causes movement of the diaphragm stem. A linkage mechanically couples the diaphragm stem to the valve stem. The linkage includes four connected links, the links attached to each other at connection points which define connection angles that are a function of positions of the diaphragm stem and valve stem. 
     In another aspect of the invention, a method of regulating pressure in a downstream region of a flowpath, the downstream region separated from an upstream region by a valve, includes moving portions of a diaphragm in housing in response to changes of pressure in the downstream region such that a diaphragm stem attached to the diaphragm also moves. The method also includes translating movement of the diaphragm stem via a linkage to cause movement of a valve stem, the valve stem operable to change the flow capacity of the valve. The linkage includes four connected links, the links attached to each other at connection points which define connection angles that are a function of positions of the diaphragm stem and valve stem. 
     The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a cross-sectional view of a regulator valve taken along its centerline. 
         FIG. 2  is a cutaway perspective view of portions of the regulator valve of  FIG. 1 . 
         FIG. 3  is a comparative side view of the linkage of the regulator valve of  FIG. 1  showing the differences between the regulator valve&#39;s open and closed positions. 
         FIG. 4  is a cross-sectional view of an alternate regulator valve taken along its centerline. 
         FIG. 5  is a cross-sectional view of another alternate regulator valve taken along its centerline. 
         FIG. 6  is a cross-sectional view of another alternate regulator valve taken along its centerline. 
     
    
    
     Like reference symbols in the various drawings indicate like elements. Terms such as top, bottom, vertical, and horizontal are used for clarity of description to note the relative locations of elements on the figures rather than to imply absolute relationships between such elements. 
     As used herein, fluid may include liquid, gas, or a combination of liquid and gas. 
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a regulator valve  10  includes a diaphragm  12  between an upper casing  14  and a lower casing  16 . Flanges  18 ,  20  and bolts  22  attach upper casing  14  and lower casing  16  to each other and hold cup-shaped diaphragm  12  in position by clamping diaphragm ends  13 . Upper casing  14  includes a lower portion  24  and an upper portion  26  which are threadingly attached to each other. An adjustment screw  28  is threaded through a bore  30  in an upper portion  26  of upper casing  14 . Adjustment screw  28  extends downward into an upper chamber  32 , which is defined by upper casing  14  and diaphragm  12 , to a spring follower  34 . A cover  36  is attached to exterior threads  38  on upper portion  26  of upper casing  14  and protects adjustment screw  28  to reduce the likelihood of inadvertent movement of the adjustment screw. 
     A spring  40  extends from spring follower  34  to a diaphragm support member  42 . Diaphragm support member  42  receives spring  40  and provides support for diaphragm  12 . Diaphragm  12  extends inwards from diaphragm ends  13 , across the annular space between diaphragm support member  42  and upper casing  14 , and along the sides and lower surface of the diaphragm support member. Diaphragm support member  42  includes an axial bore  44  which receives diaphragm stem  46 . Diaphragm stem  46  has central flanges  48 , a threaded upper end  50 , and a Y-shaped lower end with two legs  52  joined by a stem pin  54 . Diaphragm stem  46  is inserted through a central hole in diaphragm  12  and through bore  44  of diaphragm support member  42  until central flanges  48  of the diaphragm stem contact the diaphragm. Nut  56  threaded over upper end  50  of diaphragm stem  46  secures the diaphragm stem in contact with diaphragm  12  and diaphragm support member  42 . The lower end of diaphragm stem  46  contacts stop  57  when the diaphragm stem is at its lowest position. Stop  57  includes a projection  59  which limits lateral movement of diaphragm stem  46 . Thus, movement of diaphragm  12  causes corresponding longitudinal movement of diaphragm stem  46 . 
     Now referring also to  FIG. 2 , a linkage  58  connects diaphragm stem  46  to valve stem  60  and, as is described in more detail below, translates longitudinal motion of the diaphragm stem to longitudinal motion of the valve stem. As illustrated herein, valve stem  68  and diaphragm stem  86  are generally perpendicular. However, and it will be understood in the invention is not limited to such an embodiment. Linkage  58  includes a diaphragm link  62 , a seat link  64 , two connection links  66  (see  FIG. 2 ), and a linkage retainer  68 . Bolts  72  attach both sides of linkage retainer  68  to lower casing  16 . Linkage retainer  68  is pivotably attached to diaphragm link  62  and seat link  64  by a pin  70  and a pin  74 , respectively. 
     Diaphragm link  62  extends from a first end attached to linkage retainer  68  by pin  70  to a second end with two legs  78  which are inserted between legs  52  of diaphragm stem  46 . Legs  78  of diaphragm link  62  bracket stem pin  54  that is disposed between legs  52  of diaphragm stem  46 . 
     Seat link  64  extends from a first end attached to linkage retainer  68  by pin  74  to a second end with two legs  80  which are inserted between legs  82  of valve stem  60 . Legs  80  of seat link  64  bracket a pin  84  that is disposed between legs  82  of valve stem  60 . 
     Connection links  66  extend on both sides of diaphragm link  62  and seat link  64 . Connection links  66  are attached to diaphragm link  62  and seat link  64  by pins  86 . 
     Valve stem  60  extends axially through the center of a passage  88  defined by lower housing  16 . Passage  88  extends from a lower chamber  90 , defined by lower housing  16  and diaphragm  12 , to a downstream flow chamber  92  of valve body  96 . Valve stem  60  is positioned relative to the sides of passage  88  by a spoke assembly  94  which is mounted to lower housing  16 . Spoke assembly  94  include spokes (not shown) extending inwards from lower housing  16  to bushings (not shown) which allow valve stem  60  to move axially within passage  88 . Individual spokes are separated by sufficient space to permit substantially free fluid communication between downstream flow chamber  92  and lower chamber  90 . 
     A valve body  96  defines a primary fluid flow path for regulatory valve  10  which extends from inlet  98  to outlet  100  through upstream flow chamber  102 , annular valve seat  104 , and downstream flow chamber  92 . A valve closure member  106  sized to engage valve seat  104  is mounted on the end of valve stem  60 . Axial movement of valve stem  60  moves valve closure member  106  relative to valve seat  104 . In this instance, valve closure member  106  is configured as a disc. However, in other embodiments, the valve closure member can be, for example, a plug or seal that is conformable to the valve seat to limit flow through the valve. 
     In operation, regulator valve  10  is configured to maintain a pressure in downstream flow chamber  92  within a set range and, thus, provides a varying flow rate of fluid (e.g., natural gas) through the valve in response to variations in downstream demand. More specifically, the position of diaphragm stem  46  is established by the point of equilibrium between the downward force exerted on diaphragm  12  by spring  40  through diaphragm support member  42  and the upward force exerted on diaphragm  12  by fluid pressure in lower chamber  90  which is substantially equal to the pressure in downstream flow chamber  92 . 
     Adjustment screw  28  positions spring follower  34  and, thus, the position of the upper end of spring  40 . Adjustment screw  28  can be used to compensate for installation specific conditions including, for example, the condition of spring  40 . In operation, adjustment screw  28  can be operated to set regulator valve  10  to be in equilibrium for a desired downstream pressure as measured by a pressure gauge while the system is under steady state flow conditions. 
     When the pressure in downstream flow chamber  92  is within the range established by a particular setting of adjustment screw  28 , the separation between valve disc  106  and valve seat  104  has established a flow capacity for regulator valve  10  that matches the downstream load. If the downstream load increases, the pressure in downstream flow chamber  92  will begin to drop unless the flow through regulator valve  10  increases. The drop in pressure in downstream flow chamber  92  causes a substantially equivalent drop in pressure in lower chamber  90 . This reduces the upward force applied to diaphragm  12 . In response, spring  40  begins to expand, forcing diaphragm support member  42 , diaphragm  12 , and diaphragm stem  46  downward until a new equilibrium is achieved. 
     It will be understood that the valve  10  is not dependent on gravity for its operation and therefore up or down as used herein is not defined in relation to gravitational force directions. For ease of description as used herein, downward is used to describe longitudinal movement by stem  46  in a direction towards stop  57  and upwards is used to describe movement of stem  46  in a direction away from stop  57 . 
     As diaphragm stem  46  moves downward, the engagement between diaphragm link  62  and the diaphragm stem causes the diaphragm link to pivot in a counterclockwise direction about pin  70 . The movement of diaphragm link  62  is transmitted to seat link  64  by connection link  66 . This causes seat link  64  to pivot in a counterclockwise direction about pin  74 . The engagement between seat link  64  and valve stem  60  displaces the valve stem away from seat  104 . This increases the separation between valve seat  104  and valve disc  106  thus increasing the flow capacity of regulator valve  10  and stabilizing the pressure in downstream flow chamber  92 . 
     Similarly, as the downstream load decreases, the pressure in downstream flow chamber  92  will begin to rise unless the flow through regulator valve  10  decreases. Increasing pressure in lower chamber  90  moves the diaphragm  12  upwards against the resistance of spring  40 . The resulting upward movement of diaphragm stem  46  is transmitted through linkage  58  and valve stem  60  to decrease the separation between valve seat  104  and valve disc  106  thus decreasing the flow capacity regulator valve  10 . 
     Referring to  FIGS. 2 and 3 , linkage  58  is shown in  FIG. 3  as it is when regulator valve  10  is in its fully closed position (solid lines) and as it is when the regulator valve is in its fully open position (broken lines with two intervening dashes). The relationship between diaphragm link  62 , seat link  64 , connection link  66 , and linkage retainer  68  can be configured to provide a particular ratio between the amount of diaphragm movement and the amount of valve disc movement. However, the changing angles between the various links provide additional mechanical advantage to linkage  58  when the linkage is operating to move valve disc  106  towards valve seat  104 . This can provide a tighter level of control for adjustments of the capacity of regulator valve  10 . For example, in tests of one embodiment, the observed outlet pressure remained within 10% of the original set point as flow was varied. This can also provide improved mechanical reliability for regulator valve  10  by reducing the amount of spring relaxation required for fully opening the regulator valve. In addition, the amount of force applied varies with linkage position as the degree of mechanical advantage changes. 
     Referring to  FIGS. 2 and 3 , for example, as pressure decreases in lower chamber  90 , movement of diaphragm stem  46  applies a force F 1  to the linkage through stem pin  54  that is transmitted through diaphragm link  62  to connection link  66  to seat link  64  to provide a force F 2  on pin  84  to induce movement of valve stem  60 . As regulator valve  10  moves in response to input force F 1 , the angles between the various links and forces transmitted therethrough change. This is possible, in part, because stem pin  54  is slidably received in slot  109  defined by legs  78  of diaphragm link  62  and pin  84  is slidably received in slot  111  defined by legs  80  of seat link  64 . In a particular example, an interior angle ψ, defined between an axis  107  of connection link  66  and force F 2 , ranges from ψ 1  when regulator valve  10  is in its closed position to ψ 2  in the open position. As discussed above, longitudinal movement of diaphragm stem  46  pivots diaphragm link  62  in a counterclockwise direction about pin  70  and pivots seat link  64  in a counterclockwise direction about pin  74 . The resultant force on seat link  64  can be resolved into a first component parallel to valve stem  60  and a second component perpendicular to the valve stem. Because of the sliding engagement between the pin  84  and slot  111 , only the first component parallel to valve stem  60  acts on the valve stem to provide force F 2 . As angle ψ increases, the second component perpendicular to valve stem  60  increases and the first component parallel to the valve stem decreases. Thus, as angle ψ increases, the mechanical advantage or ratio between force F 2  and force F 1  (i.e., F 2 /F 1 ) decreases. In some embodiments, interior angle ψ has a range between about 15 and 60 degrees (e.g., between 25 and 50 degrees). 
     Referring to  FIG. 4 , an alternate regulator valve  110  has similar construction and operation. The primary difference from above-described regulator valve  10  is that lower chamber  90  of regulator valve  110  is not in direct fluid communication with downstream flow chamber  92 . Spoke assembly  94  of regulator valve  10  is replaced by annular support assembly  112  which substantially prevents fluid flow along the outside of valve stem  60  between lower chamber  90  and downstream flow chamber  92 . Bore  114  provides an attachment point for piping (not shown) which extends from lower casing  16  to some portion of the flow path downstream of regulator valve  110 . This piping provides for fluid communication and the transmission of a pressure signal through, for example, direct application of flow or through a pilot regulator to lower chamber  90 . 
     Referring to  FIG. 5 , another alternate regulator valve  210  also has similar construction and operation. Regulator valve  210  includes a spoke assembly  94  as described above in the discussion of regulator valve  10 . In this embodiment, an opening  212  in casing  16  is used as an attachment point for a pressure relief module  214 . Pressure relief module  214  includes a casing  216  which is threadingly attached to opening  212 . A relief module spring  218  extends axially within casing  216  from a spring adjustment fitting  220  to a spring seat  222 . Spring adjustment fitting  220  includes exterior threads which engage interior threads of a casing  216 . Spring adjustment fitting  220  also includes a central cavity  224  which is configured to receive an adjustment tool (not shown) such as, for example, a hex wrench. Relief module spring  218  biases a relief valve disc  226  towards engagement with a relief valve seat  228 . Spring adjustment fitting  220  can be positioned such that increasing pressure in the lower chamber  90  will compress relief module spring  218  and disengage relief valve disc  226  from relief valve seat  228  before the increased pressure damages diaphragm  12  or spring  40 . This allows fluid to flow through relief valve seat  228  and out aperture  230 . 
     Referring to  FIG. 6 , another alternate regulator valve  310  includes a similar linkage  58  between diaphragm stem  46  and valve stem  60 . In this instance, an annular fitting  312  couples diaphragm stem  46  with stem extension  314 . A lower end of spring  40  engages a lower spring seat  316  that is mounted in lower portion  24  of upper casing  14 . Spring  40  extends upward around stem extension  314  to spring follower  34  and biases the spring follower upwards against shoulders  316  of the stem extension. Thus, spring  40  biases stem extension  314 , diaphragm stem  46 , and diaphragm  12  upwards rather than downwards as previously described. As previously described herein, the ends of diaphragm  12  are secured between upper casing  14  and lower casing  16 . However, diaphragm support member  42  is inverted relative to its orientation in the previously described regulator valves and diaphragm  12  extends over the upper surface of the diaphragm support member between the diaphragm support member and a diaphragm disc  318 . Diaphragm disc  318  can help protect diaphragm  12  from damage caused by wear. 
     An upper bore  320  in lower portion  24  of upper casing  14  provides an attachment point for a pressure loading mechanism (not shown). For example, a pilot regulator can be configured to increase/decrease the pressure in upper chamber  32  in response decreasing/increasing pressure at a point downstream of the regulator valve  310 . Such pilot regulators are described in more detail in U.S. Pat. No. 6,354,319, the entire contents of which are incorporated herein by reference. The adjustment screw included in previously described regulator valves is omitted and replaced by a plug  322 . In some instances, adjustment of the overall system is performed by calibrating and adjusting the pressure loading mechanism. 
     In operation, as pressure in upper chamber  32  increases due to loading from the pressure loading mechanism, diaphragm  12  and diaphragm support member  42  are moved downward against the bias of spring  40 . Thus, increasing pressure in the upper chamber  32 , rather than decreasing pressure in lower chamber  90 , increases the flow capacity of regulator valve  310 . Embodiments with a pilot regulator can provide the increased degree of control that is characteristic of pilot regulators as well as variable-rate control provided by multi-bar linkage  58 . 
     A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, an electronic control system could respond to electronic signals from a downstream pressure sensor by using a linear electronic solenoid to apply motive force to the linkage. In another example, more than four connected links could form the linkage between the diaphragm stem and valve stem. Accordingly, other embodiments are within the scope of the following claims.