Abstract:
An assembly for limiting excess flow includes a seat and a disc. The seat has an inner ring, an outer ring having a top surface tapering in a downstream direction from outer ring towards the inner ring, and a plurality of legs attaching the inner ring to the outer ring. The disc attaches to the inner ring and extends radially outwardly therefrom. The disk has an axially downstream surface that flexes into contact with the outer ring if the flow exceeds a limit around the disc, and a shoulder spacing the axially downstream surface from the inner ring to space the disc axially from the outer ring.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention generally relates to an excess flow check valve that permits fluid flow through a flow line if the flow is below a predetermined flow rate but minimizes the flow line if the flow rate rises above the predetermined limit to prevent uncontrolled flow or discharge of fluids. 
       SUMMARY OF THE INVENTION 
       [0002]    Excess flow valves are typically used in a capsule to facilitate its installation in various flow lines, fittings, pipe systems, appliances and the like. The excess flow valve acts in response to a high or a low differential pressure between the upstream pressure and downstream pressure of the capsule. The capsule usually has four portions comprising a seat, a housing, a valve plate or body, and a spring or magnet to bias the valve plate. The capsule may be inserted in various flow passageways including a valve body, a connector fitting, a hose fitting, a pipe nipple, a tube, an appliance and other similar installations to provide excess flow protection. 
         [0003]    A capsule facilitates assembly of the individual components into a self-contained compact package, provides for easy insertion of the capsule into a fitting or tube, provides a substantial restriction, provides a small leakage flow for automatic valve resetting, precisely positions and retains the components of the valve for proper operation, provides a unique structure for coupling the two capsule components, permits flow testing as a capsule to verify performance, and provides a compact configuration to minimize the size, diameter and length required to accommodate the capsule. 
         [0004]    According to an embodiment described herein, an assembly for limiting excess flow includes a seat and a disc. The seat has an inner ring, an outer ring having a top surface tapering in a downstream direction from outer ring towards the inner ring, and a plurality of legs attaching the inner ring to the outer ring. The disc attaches to the inner ring and extends radially outwardly therefrom. The disk has an axially downstream surface that flexes into contact with the outer ring if the flow exceeds a limit around the disc, and a shoulder spacing the axially downstream surface from the inner ring to space the disc axially from the outer ring. 
         [0005]    According to an embodiment described herein, a method of creating an assembly for limiting excess flow includes the steps of: providing a seat, the seat having an inner ring, an outer ring having a top surface from outer ring towards the inner ring, and a plurality of legs attaching the inner ring to the outer ring, selecting a taper angle of the outer ring in a downstream direction from an outer periphery thereof, and providing a flexible disc attaching to the inner ring and extending radially outwardly therefrom, the disk having a axially downstream surface that flexes into contact with the outer ring if the flow exceeds a limit around the disc, and providing a shoulder spacing the axially downstream surface from the inner ring to space the disc axially from the outer ring. 
         [0006]    These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  shows a gas coupling pipe including an excess flow assembly. 
           [0008]      FIG. 2  shows a first embodiment of an excess flow assembly used in the pipe of  FIG. 1  in a first position and a second condition. 
           [0009]      FIG. 3  shows the unassembled excess flow assembly shown in  FIG. 2 . 
           [0010]      FIG. 4  shows a taper angle from an outer ring to an inner ring. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0011]    Referring now to the Figures, gas connector  5  includes a fluid pipe  10  having an inlet coupling  15 , an outlet coupling  20 , and an excess flow assembly  25 . The pipe may carry different fluids, such as natural gas, or other gases or liquids. The assembly  25  is molded or cast as separate pieces. Fluid flows in the direction F through the excess flow assembly  25 . The pipe  10  extends along an axis  47 . 
         [0012]    The pipe  10 , which may have corrugations  30 , has a non-corrugated area  35  that holds the assembly  25 , which is bounded by a radially inwardly depending shoulder  40 , which may be a groove, and an expanded area  45  for interacting with the excess flow assembly  25  as will be discussed infra. 
         [0013]    The expanded area  45  has an increased diameter D e  relative to the diameter D c  of the non-corrugated area  35  to provide more area for fluid flow around and through the assembly  25 . 
         [0014]    The inlet coupling  15  and the outlet coupling  20  each have a housing  50  that surrounds flared ends  55 , as are known in the art, of the pipe  10 . The housings  50  each have an internal thread  60  for mating with external threads (not shown) of a gas supply line (not shown) at the inlet coupling  15  and with the external threads (not shown) of an appliance (not shown) at the outlet coupling  20 . 
         [0015]    Referring now to  FIGS. 2 and 3 , the two-piece assembly  25  has two basic components, a valve seat  65 , and a flexible umbrella  70 . The umbrella  70  is made of a flexible, fluid resistant material such as rubber or silicone or the like. The valve seat  65  may be made of a stiffer fluid resistant material, like plastic, or the like. The assembly  25  may also be made in one piece by using a co-injection process where one of the valve seat  65 , and the flexible umbrella  70  are molded first and the other of the valve seat  65  and the flexible umbrella  70  are molded atop, or into, the other of the valve seat  65  and the flexible umbrella  70 . The stiffness of the umbrella  70  may be adjusted for differing applications depending on flow rates required in a particular application. 
         [0016]    The valve seat  65 , which is generally cylindrical, has a centrally disposed passageway  75  for receiving the umbrella  70 , an inner ring  80 , an outer ring  85  and a plurality of legs  90  connecting an outer periphery  91  of the inner ring to an inner periphery  93  of the outer ring  85 . The outer ring  85  has an interference fit within the non-corrugated area  35  so that fluid does not escape around the outer ring  85 . The legs  90  define fluid flow areas  95  therebetween such that fluid may flow about the umbrella  70  during normal operation and through the fluid flow areas  95 . A top surface  100  of the outer ring  85  and a top surface  105  of the legs  90  taper axially downstream from the outer ring  85  to the inner ring  80 . A top surface  110  of the inner ring  80  may also taper. The angle a of the taper depends on required flow rates in a particular application. As an angle of the taper increases axially downstream, the amount of flow through the assembly  25  may increase. 
         [0017]    The umbrella  70  has a central shaft  115  that extends through the passageway  75 . The umbrella  70  acts as a valve. The central shaft  115  may be anchored within the passageway  75  by gluing, sonic welding, by an expanded area  120  that is press fit in the passageway  75 , or the like. The shaft has a spacing portion  125  having a bottom surface  130  that sits on the top surface  110  of the inner ring  80 . As with the taper angle a, the length of the spacing portion creates space between the umbrella and the valve seat  65  to measure flow at the appropriate amount. A disc  135  extends concentrically and axially upstream from the central shaft  115 . The disc  135  has a flat upstream surface  140  and a curved or tapered (i.e. shaped) downstream portion  145  that mates with the taper of the top surface  100  of the outer ring  85  as will be discussed infra. The curved downstream portion  145  extends from the spacing portion  125  to a peripheral edge  150 . 
         [0018]    A notch  155  may be cut in the disc  135  to allow the assembly  25  to reset itself if an excess flow condition no longer exists as is known in the art. The disc  135  may also have a pin-hole  160  cut through it for the same purpose. 
         [0019]    During normal operation in which there is no excess flow, fluid such as natural gas, flows through the pipe  10 , around the disc  135 , between the legs  90  and through the flow fluid flow areas  90 . Because the expanded area  45  increases the area of flow of gas around the assembly  25 , and because there is room around the disc  135  because of the height of the spacing portion  125 , there is relatively little pressure drop as the fluid flows by the disc  135 . The disc  135 , therefore, does not flex and stays in position A shown by the solid lines in  FIG. 2 . 
         [0020]    If there is a breakage or the like in the pipe  10 , fluid flow through the assembly  25  may not be limited by an appliance (not shown) and there is a risk that fluid may flow above a given limit without obstruction. The pressure drop upstream and downstream of the assembly  25  increases greatly due to the increased flow and the disc  135  flexes and is induced towards the valve seat  65  to seat against the top surface  100 ,  105  of the outer ring  85  and legs  90  in position B (see the dotted lines in  FIG. 2 ). The curved downstream portion  145  mates with the taper of the top surface  105 . 
         [0021]    Fluid may leak through the notch  155  or the pinhole  160  to allow pressure to equalize upstream and downstream of the disc  135 . After the pressure is equalized, such as if the pipe  10  is fixed, the flexibility of the umbrella  70  allows the valve plate to return to position A, thereby allowing gas to flow through the cartridge  25 . 
         [0022]    Although a combination of features is shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of this disclosure. In other words, a system designed according to an embodiment of this disclosure will not necessarily include all of the features shown in any one of the Figures or all of the portions schematically shown in the Figures. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments. 
         [0023]    The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims.