Abstract:
A single stage vacuum breaker flow regulator includes a diaphragm retained in an elevated position in between atmosphere and an outlet chamber for a gaseous medium. A valve in communication with an inlet chamber is yieldingly urged to a closed position by a spring. Cam levers are movable by the diaphragm upon a reduction in pressure to sub-atmospheric in the outlet chamber. The movement of said cam levers in response to a reduction in pressure is transmitted to a yieldingly movable valve to open said valve to the flow of gas from said inlet chamber to said outlet chamber.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of U.S. Provisional Patent Application No. 61/211,866 filed Apr. 3, 2009. 
    
    
     BACKGROUND OF THE INVENTION 
     Gas flow regulators for medical, instrumentation and other purposes come in a number of different varieties. One such type of gas flow regulator is known as a demand flow regulator, one model of which is described in U.S. Pat. No. 5,665,894. The gas flow regulator disclosed in U.S. Pat. No. 5,665,894 is a two stage regulator. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a single stage vacuum breaker flow regulator. It is a low cost, highly accurate device which can be precisely set or adjusted to suit the desired actuation pressure and flow desired by the user. This is accomplished through the use of a balanced valve poppet that is able to supply gas from a positive source as needed into a sub-atmospheric chamber as required by the process or instrument. 
     Objects and advantages of the present invention will become apparent to those skilled in the art upon a review of the following detailed description of the preferred embodiments and the accompanying drawings. 
    
    
     
       IN THE DRAWINGS 
         FIG. 1  is a top plan view of the regulator of the present invention. 
         FIG. 2  is an enlarged sectional view taken along line A-A of  FIG. 1 . 
         FIG. 3  is an enlarged sectional view taken along line B-B of  FIG. 1 . 
         FIG. 4  is a sectional view taken through line C-C of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings there is shown a single stage vacuum breaker flow regulator  10 . 
     The vacuum breaker flow regulator  10  includes a body  12  with an inlet  63 , a barb-hose type outlet  64  and a chamber  30  which extends along axis A upwardly from the lower surface  16  of the body  12 . A pressure gauge  70  is mounted on the body  12  in an area approximately 90° from each of the inlet  63  and outlet  64  and communicates with the chamber  30  by means of lateral passageway  72 . A safety relief  18  is mounted on the body  12  in an area generally opposite the pressure gauge  70 . The safety relief is one of standard type in the field of gas flow regulators and does not need further description. The inlet  63  includes a reduced size passageway  65  extending to the chamber  30 . 
     Positioned in the chamber  30  is a balanced poppet valve  19  extending from a reduced size lower extension  19 A to an enlarged upper flange  19 B having a radially extending shoulder  19 C at the lower end thereof. A central section  19 D extends between the lower extension  19 A and the radially extending shoulder  19 C and is spaced from the sidewall of chamber  30 . Additionally, the enlarged upper flange  19 B has at least one area in its outer periphery, such as a flat panel for example, which is spaced from the sidewall of the chamber  30  in order to permit the flow of gas therearound when the valve is open. Balancing the poppet valve reduces the effect of changing inlet pressure on the cracking pressure of the regulator. 
     Encircling the poppet valve extension  19 A and a major portion of the central section  19 D of the poppet valve  19  is a valve housing  20  having a lower axial passageway  22  in which the lower poppet valve extension  19 A is slidably positioned. The lower axial passageway  22  and, therefore, the end of the reduced size lower extension  19 A are at atmospheric pressure. The valve housing  20  is positioned in the lower area of body chamber  30  and has a lower chamber  24  in which is positioned a Teflon® back-up ring  26  and an O-ring seal  28  effecting a seal between the chamber  24  and the poppet valve extension  19 A. Above the reduced size lower chamber  24  of the valve housing  20  is an enlarged upper chamber  31 . A valve guide  32  is positioned in the upper chamber  31  and has a lower reduced size portion  32 A which extends into the reduced size lower chamber  24 . A compression spring  34  is positioned in the upper chamber  31  and its lower end rests against the valve guide  32 . The compression spring  34  extends out of the valve housing  20 , into the body chamber  30  where its upper end engages the radially extending shoulder  19 C to yieldingly urge the poppet valve  19  to a sealed position. 
     The regulator body  12  has an upper passageway  38  permitting the flow of fluid to and from the chamber  30 . The upper passageway  38  is the same diameter as the lower axial passageway  22  of the valve housing  20 . A Teflon® seal  36  is positioned at the upper end of the poppet valve  19  and has an outwardly convexed sealing surface  36 A which engages and effects a seal of said upper passageway  38 . A stainless steel collar  40  encircles a reduced size upper portion of the Teflon® seal  36  to support it in the recess of the enlarged upper portion  19 B of the poppet valve  19 . 
     The upper surface  30 A of the chamber  30  tapers downwardly in a direction toward axis A in order to permit the convex upper surface  36 A of the Teflon® seal  36  to effect a sound seal to close the passageway  38  when so desired. Connected to and extending from the Teflon® seal  36  is an actuator pin  44  having a lower cylindrical portion which extends through passageway  38  outwardly from the fluorocarbon seal  36  along axis A. The actuator pin  44  extends from its lower cylindrical portion received in the Teflon® seal  36  to a conical portion  44 A from which extends a hexagonal head portion  44 B. The conical portion  44 A and enlarged hexagonal head portion  44 B are positioned in a cylindrical outlet chamber  46  at the upper end of the body  12 . As a result of the actuator pin hexagonally shaped head portion  44 B being positioned in a chamber  46  which is cylindrical in shape, flow passages are provided between the hex flats of the enlarged head  44 B and the cylindrical wall of the chamber  46 . Additionally, the lower cylindrical portion of the actuator pin  44  is smaller in diameter than passageway  38  thereby permitting gas to flow through passageway  38  around the outside of the lower cylindrical portion. This coupled with the equal areas of the lower axial passageway  22  (with stem  19 A, seal  28  and backup ring  32 A) and the upper axial passageway  38  (with seat  36 ) provides a balancing effect of the forces on the poppet valve  19 . This balancing of areas negate the effect of changing inlet pressures on the sensitivity and cracking pressure of the regulator and reduces the force required to open the valve. 
     The upper end of the body  12  has an upper surface  12 A and a substantially cylindrical wall  128  extending upwardly therefrom. The cylindrical wall  128  terminates in a radially outwardly extending flange  12 C. The flange  12 C defines a circle and serves to support the outer edge of a deformable diaphragm  50  and bonnet  52 . The diaphragm  50  includes an upper elastomer sheet  50 A adhered to a thin stainless metal disk  50 B. The metal disk provides rigidity to the center portion of the diaphragm so that as the diaphragm is moved downward, the diaphragm deformation takes place in the edge convolution  50 D. The bonnet  52  has, at its outer periphery, a downwardly extending U-shaped portion  52 A which engages the outer periphery of the diaphragm  50 . An upwardly extending collar  12 D is formed inwardly to clamp the bonnet  52  and the diaphragm  50  to the radial flange  120  of the housing  12  and form a diaphragm seal. 
     Positioned in the space  67  between the diaphragm  50  and the upper surface  12 A of the body  12  is a loading lever  54  formed of stainless steel. The loading lever  54  has a thickness on the order of 0.090 inch which is sufficient to provide significant rigidity to the loading lever to permit it to act upon the poppet valve to move the poppet valve  19  to an open position when the loading lever is caused to move downwardly as hereinafter described. A pair of cam levers  56  are pivotally supported in the space  67  between the diaphragm  50  and the loading lever  54  by means of a pin extending through an aperture  56 A of each cam lever. Screws  81  engage and hold in position opposing ends of each pin extending outwardly from the aperture  56 A of each cam lever. The cam levers  56  are resiliently urged to an angle upwardly into contact with the metal member  50 B of the diaphragm  50  by means of upward urging of the loading lever  54  by the spring  34 . Threadedly engaged to the loading lever  54  is an adjusting screw  58 . The adjusting screw  58  can be rotated to move the loading lever  54  and the pivoted ends  56 A of the cam levers  56  to thereby precisely set the regulator to a position for opening the poppet valve  19  at the precise amount of pressure as demanded by instrumentation attached to the outlet  64  of the regulator as shown in  FIGS. 1 and 2 . Rotation of the adjusting screw  58  moves the loading lever  54  and the cam levers  56  to a position at which the free ends  56 B touch the stainless metal disk  50 B of the diaphragm  50  but do not put any significant force on it. 
     Upon a reduction in pressure in the space  67  occupied by the cam levers  56  as a result of the demand for gas from an outside source, the diaphragm  50  will be sucked downwardly thereby pushing the free ends  56 B of the cam levers  56  into engagement with the loading lever  54  and its adjusting screw  58  to thereby push the loading lever  54  and screw  58  downwardly to a position at which they engage the upper end of the hexagonally shaped portion  44 B of the actuator pin  44 . Continued movement downwardly moves the poppet valve  19  downwardly against the resilience of spring  34  to disengage the Teflon® seal  36  from the upper surface  30 A of the chamber  30 , and thereby opening the passageway  38  to permit the flow of gas. The metal member  50 B protects the elastomer sheet  50 A from being damaged by the cam levers  56 . 
     The demand for gas by outside instrumentation connected to the outlet  64  communicating with the space  67  below the flexible diaphragm  50  by means of passageway  66  creates a partial vacuum which causes the flexible diaphragm  50  to be drawn downwardly carrying with it the cam levers  56 , the free ends of which then contact the loading lever  54  pushing it and adjusting screw  58  downwardly to a position contacting the enlarged head of the actuator pin  44 . Continued downward movement of the loading lever  54  causes the Teflon® seal  36  to move downwardly out of engagement with upper surface  30 A thereby opening the passageway  38  to the flow of gas to the outside instrumentation through outlet  64 . As previously noted adjustment of the screw  58  permits precise adjustment of pressure and the flow of gas. 
     The diaphragm  50  acts as a sensing element to control, the movement of the fluorocarbon  36  and, thereby, the opening and closing of the passageway  38 . By virtue of the diaphragm  50 , the regulator of the present invention has a sensitivity such that it can be opened at a much lower pressure (crack pressure) than prior art vacuum breaker/demand flow regulators. Thus, the regulator of the present invention can be opened at a vacuum pressure of 1.5 inches of water pressure (005 psig) as compared with prior art demand regulators which require crack pressures of 3 inches of water pressure or more. This degree of sensitivity, coupled with the feature of the adjusting screw  58  provides a vacuum breaker/demand flow regulator with greater sensitivity than similar types of prior art regulators. A significant feature of the present invention is the balancing effect resulting from equal areas of the poppet valve extension  19 A and seals in lower axial passageway  22  of the valve housing  20  and the sealing area created by the seal  36  sealing upper passageway  38 . 
     The above detailed description of the present invention is given for explanatory purposes. It will be apparent to those skilled in the art that numerous changes and modifications can be made without departing from the scope of the invention. Accordingly, the whole of the foregoing description is to be construed in an illustrative and not a limitative sense, the scope of the invention being defined solely by the appended claims.