Abstract:
A poppet mounted concentrically on a barrel for axial travel downstream relative thereto from an open to closed position, the poppet biased by a coil sprint to its open position.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to valve devices responsive to an upsurge in flow rate to throttle or shut off the flow. 
         [0003]    2. Description of the Prior Art 
         [0004]    Natural gas is recognized as a relatively clean and inexpensive fuel source. Distribution systems are typically installed as part of a metropolitan or residential infrastructure to supply gas to the end users. Typically, a main gas line is laid and branch lines fed off the main line to the sites for individual gas meters, appliances, and the like. Natural gas is recognized as having high flammability such that uncontrolled escape thereof by rupture of the gas pipe line or branch line can create an extremely hazardous situation. An escape of natural gas into a confined space and exposure to any spark or any other ignition source can create an extremely volatile explosion. 
         [0005]    In recognition of this fact, numerous different excess flow shut off valves have been proposed and are intended to be responsive to a abnormal surge in gas flow to close or throttle to thus minimize or stop gas flow. Typical of prior excess flow control valves are poppets biased to an open position by an internal coil spring which is responsive to a sudden pressure drop to discontinue flow. Ay such devices are made up of multiple machined components rendering them relatively expensive and often times provide a rather circuitous flow path, sometimes occupied in part by a coil spring which may hinder flow or otherwise add to the turbulence of flow thereby creating an unwanted pressure drop during normal operation. 
       SUMMARY OF THE INVENTION 
       [0006]    The excess flow control valve of the present invention includes a barrel defining a valve body having a through passage and formed on its upstream end with a valve seat. A poppet cage received in telescopical relationship with the upstream end of the barrel is formed with radially opening inlet ports and is closed on its upstream end by a poppet cap having a downstream facing peripheral seal surface which is operative to, when the poppet is in its closed position, throttle or stop flow past the valve seat. The poppet is biased is upstream with a predetermined force by means of a coil spring about the body barrel. 
         [0007]    Other features and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the features of the invention. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a perspective view of an excess control valve embodying the present invention; 
           [0009]      FIG. 2  is a left hand end view thereof, in enlarge scale; 
           [0010]      FIG. 3  is a right hand end view thereof, in enlarge scale; 
           [0011]      FIG. 4  is front view, in enlarge scale, of the valve shown in  FIG. 1 ; 
           [0012]      FIG. 5  is an exploded perspective view, in enlarge scale, of the excess flow control valve shown in  FIG. 1 ; 
           [0013]      FIG. 6  is a transverse sectional view taken along the line  6 - 6  of  FIG. 5 ; 
           [0014]      FIG. 7  is a transverse sectional view taken along the line  7 - 7  of  FIG. 5 ; 
           [0015]      FIG. 8  is a transverse sectional view taken along the line  8 - 8  of  FIG. 5  but rotated 15° about the longitudinal axis; 
           [0016]      FIG. 9  is a transverse sectional view taken along the line  9 - 9  of  FIG. 5 ; 
           [0017]      FIG. 10  is a transverse sectional view taken along the line  10 - 10  of  FIG. 5 ; 
           [0018]      FIG. 11  is a longitudinal sectional view, in enlarge scale, of the excess flow control valve shown in  FIG. 1  mounted in a fluid flow conduit; 
           [0019]      FIG. 12  is a transverse sectional view taken along the line  12 - 12  of  FIG. 11 ; 
           [0020]      FIG. 13  is a longitudinal sectional view similar to  FIG. 11  but showing the valve in its closed position; and 
           [0021]      FIG. 14  is a detailed sectional view, in enlarge scale, taken from the circle designating  14  in  FIG. 13 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0022]    Referring to  FIGS. 5 and 11 , the excess flow control valve of the present invention includes, generally, a barrel  31  formed with a through flow passage  33  and terminating at its upstream end in a valve seat  37  ( FIGS. 13 and 14 ). A poppet, generally designated  39 , includes a mounting ring  41  received telescopically over the barrel  31  for sliding longitudinally thereon and incorporates a cap  43  spaced upstream therefrom to cooperate in forming radial inlet ports  45  and formed at its periphery in an annular downstream facing sealing surface  46 . A coil spring  47  is received telescopically over the barrel  31  and biases the poppet  39  upstream with a predetermined force so that flow of gas in the downstream direction as shown by the directional arrows in  FIG. 11  will flow radially inwardly through the ports  45  and through the internal flow passage  33  creating a pressure drop across the poppet. In the event, a gas line should burst downstream of the valve, flow will be increased thus increasing the pressure drop across the poppet. When such flow rate reaches the point where the pressure drop across the poppet exceeds the bias force of the spring  47 , the poppet will be moved to its closed positioned shown in  FIG. 13  engaging the poppet seal surface  46  with the seat  37  to shut off gas flow. 
         [0023]    The barrel  31  may be constructed of any desired material such as Zink, steel or plastic or the like and is preferably formed with the interior flow passage  33  expanding slightly radially outwardly in the downstream direction. The barrel is configured at is upstream end with an annular rim rounded off to define a convex edge serving as the seat  37 . 
         [0024]    The barrel is formed exteriorly towards its downstream extremity with a plurality of axial circumferentially spaced, longitudinal ribs  44  cooperating at their collective radial outer extent to define a cylindrical profile. The ribs terminate at their respective upstream extremities in radially inward cutbacks defining respective upstream facing shoulders  49  and axially upstream projecting stub ribs  51  also cooperating in to form a cylindrical profile reduced in diameter from that of the profile defined by the collative main body of the ribs themselves. 
         [0025]    The barrel  31  is formed exteriorly at its downstream extremity with a radially outwardly opening O-ring gland  53  for receipt of an O-ring  55 . The exterior of the barrel is formed just upstream of the gland  53  with a radially outwardly annular opening anchor groove  57 . 
         [0026]    The barrel is formed at its upstream extremity behind the seat  37  with a plurality of radially outwardly projecting circumferential stop ring segments, the confronting radial ends of adjacent segments  57  being spaced circumferentially apart to form therebetween respective axial slider passages  61  ( FIG. 5 ). The exterior of the barrel  31  is further formed medially with a plurality of pairs of circumferentially spaced apart wedge shaped teeth  63  and  65  tapering radially outwardly and circumferentially toward one another cooperating to form between the thick ends of each pair an axial track  69  of a predetermined circumferential width. Such teeth  61  and  65  are positioned to form the respective tracks  69  off set from axial alignment with respective passages  61  so as to be disposed in axial alignment with the medial portions of the ring segments  57 . 
         [0027]    The poppet may be constructed of injection-molded plastic and the ring  41  is preferably formed with a degree of flexibility so it can spring to some extent from its round cross sectional shape. The poppet ring  41  mounts spaced equidistant about its radial interior a plurality of axial sliders  71  which project axially downstream from the downstream end of such ring to form stabilizing tabs  72  formed with a predetermined circumferential width slightly less than the width of the respective tracks  69  between the teeth  63  and  65  to be received in sliding relationship therewith ( FIG. 12 ). 
         [0028]    The poppet  39  is configured with axial struts  75  spaced circumferentially equidistance thereabout projecting upstream of the ring  41  and bent radially inwardly on the respective upper extremities to mount the cap  43  and form therebetween the respective radially inwardly opening fluid inlet ports  45 . The cap  43  is preferably formed with a semi-spherical upstream convex nose which is configured at its periphery with a frusto-conical flange  76  formed to define the sealing surface  46  on the downstream surface thereof ( FIG. 14 ). The cap is formed centrally with a downstream projecting stem  77  ( FIG. 11 ) configured with an internal lightening bore  79  which expands radially outwardly in the downstream direction along a tooling draft angle. 
         [0029]    In practice, it will be appreciated that the components of the excess flow control valve of the present invention may be manufactured by machining, molding or any other of a number of different manufacturing processes well known to those skilled in the art. The barrel  31  may be cast, molded or machined to be formed integrally with the annular gland  53 , ribs  44 , teeth  63  and  65  and ring segments  57  as well as the annular seat  37 . The poppet  39  may be constructed of injection molded plastic. During assembly, the coil spring  47  may be telescoped over the upstream end of the barrel  31  to abut on its downstream end with the rib shoulders  51  ( FIG. 5 and 13 ). The poppet may be moved into position with the respective tabs  72  of the slider  71  slid axially through the passages  61  formed between the respective ends of adjacent pairs of ring segments  57  to slide in the downstream direction into the annular space formed between the coil spring  47  and the exterior of the body to abut the downstream end of the ring  41  against the upstream end of the spring. Forcing the poppet further in the downstream direction will cause the spring  47  to be further compressed allowing the poppet to be shifted axially until the upstream ends of the respective sliders  71  clear the downstream edges of the respective ring segments  57  to free the poppet for rotation relative to the barrel  31 . The poppet may then be rotated about such barrel allowing the respective sliders  71  to engage respective ones of the teeth to ride radially outwardly thereon as permitted by flexing out of round of the ring causing such sliders to register with the respective tracks  69  between the respective pairs of teeth  63  and  65  to be received therein. Once the sliders are registered, the inherent resiliency of the ring will drive then radially inwardly in the respective tracks to be held slidably thereon. The workman may then release the poppet  39  permitting the bias in the spring  47  to drive such poppet in the upstream direction as the sliders travel in the respective tracks  69  until the upstream ends thereof strike the downstream edges of the respective ring segments. This serves to bias the poppet to its open position with a force dictated by the spring constant. 
         [0030]    My preferred embodiment of the invention includes a tubular annular shroud  58  to be telescoped on the barrel to form a capsule. The shroud  58  will typically be constructed of stainless steel sheet metal or plastic and may be constructed on its downstream end with a radially inturned annular anchor flange  56  having an internal diameter slightly larger than the diameter of the profile for the collective axial ribs  44 . The shroud is preferably formed at its upstream extremity with a radially outwardly projecting bead  60 . The shroud and bead are formed so the diameter of such shroud is slightly less than the inside diameter of the gas line  80  into which it is to be received and the outside diameter of the bead slightly larger. Such shroud may thus be telescoped over the upstream end of the barrel  31  to pass over the ring segments  57 , teeth  63  and  65  and over the ribs  44  to register with the anchor groove  50 . The downstream end of the shroud may then be crimped radially inwardly to drive the flange  56  into the ground  50  to anchor such shroud in a fix position relative to the barrel  31 . The O-ring  55  may then be inserted over the downstream end of the barrel  31  to be received in the gland  53 . 
         [0031]    In a typical application, excess flow valves may be inserted in different branch gas lines to individual business establishments or residences. In practice, the walls of the branch lines  80  are typically constructed of polyethylene with some degree of stretch. Consequently, the entire capsule may be inserted into the end of the polyethylene tubing causing the annular bead  60  to stretch the tubing outwardly as the capsule snakes up the line to thus maintain a firm grip thereon. As the valve capsule is driven further into the distribution line, the O-ring  53  will sealingly engage the interior wall of such line to maintain a fluid tight seal when gas is flowed through the valve. 
         [0032]    It will be appreciated that the spring  47  is selected with a constant such that when gas flows under normal conditions in the direction of the directional arrows in  FIG. 11 , it will present sufficient bias to resist the dynamic head applied to the nose  43  of the poppet causing the gas to flow in a more or less laminar pattern over the convex shape of such nose radially outwardly and downstream thereabout to flow radially inwardly through the respective inlet ports  45  and through the relatively unobstructed, rather robust fluid passage  33  in the barrel  31 . It will be appreciated that flow through the fluid passage  33  is relatively unrestricted, particularly as influential by the downstream expansion of the passage. 
         [0033]    In the event there should be a line burst, leakage or other accident that might result in escape of gas downstream of the valve, it will appreciated that the pressure will drop within such valve causing an increase pressure differential across the valves of the poppet. This will cause the velocity of gas through the inlet ports  43  to increase and flow through the passage  33  to increase thereby further increasing the pressure differential across the poppet to the point where that pressure differential, combined with any dynamic forces from the flow striking the nose  43 , overcomes the bias of the spring  47  to thus initiate compression of that spring. As the pressure differential across the poppet overcomes the spring bias, the poppet will be driven downstream relative to the barrel causing the respective inlets  45  to be partially occluded by the side walls of the barrel thus further reducing the pressure within the food passage  33  thereby further increasing the pressure differential across the poppet to the point where the poppet is driven to its closed position engaging the sealing surface  46  on the annular seat  37  ( FIGS. 13 and 14 ) thereby totally closing off flow and preventing any additional escape of gas. It will be appreciated that both the surface of the seat  37  and the sealing surface  38  may be complementally shaped, preferably convex for the seat and a complimentary concave shape for the sealing surface to thereby enhance the positive sealing of the poppet to prevent unwanted escape of volatile gases. 
         [0034]    In practice, the foregoing operation for the preferred embodiment will cause the poppet to respond to a precipitous drop in the downstream pressure to abruptly close. It will be appreciated, however, that for some embodiments the poppet may respond to a diminished pressure to partially close thus throttling flow or even seeking a steady state reduced volume flow rate to produce a pressure reduction across the value itself without a complete shut off. 
         [0035]    As it will be appreciated by those skilled in the art, it is convenient in the preferred embodiment to position the poppet spring telescopically over the exterior of the valve barrel but that in other embodiments the poppet and its associated bearing ring may take different forms, as for instance, telescoping into the exterior of the barrel wherein, in some instances, the barrel itself may be stepped on the interior to accommodate sliding of such ring. The nose of the poppet is preferably spherical but may, of course, take other forms such as parabolic, pyramidal or even, some instances planes. 
         [0036]    From the foregoing, it will be appreciated that the excess flow control valve of the present invention provides an economical and effective means for throttling or stopping flow in the event of a line rupture or the like. The valve provides for minimum flow respective and maximum volume in the gas fluid distribution line and is economical and convenient to manufacture and install. The components are relatively inexpensive to manufacture and are few in number thus rendering fabrication and assembly relatively straight forward.