Patent Publication Number: US-3877484-A

Title: Pneumatic relay

Description:
Theriot et al.  
 1 PNEUMATIC RELAY [75] Inventors: Gerold F. Theriot, Bourg; Frank M.  
 Hoofnagle, Houma, both of La.  
 [73] Assignee: B. W. B. Controls, Inc., Houma, La.  
 [22] Filed: Sept. 6, 1973 [21] Appl. No.: 394,849  
 [52] US. Cl l37/625.66; 137/458 [51] Int. Cl. Fl6k 17/00 [58] Field of Search 137/456, 458, 464,466, 137/625.66  
 [56] References Cited UNITED STATES PATENTS 2,871,876 2/1959 Edmund 137/464 2,879,789 3/1959 Towler et a1 137/456 3,621,881 11/1971 Vicari 137/458 12/1972 Paulivkonis ..137/625.66 6/1973 Kaemmer l37/625.66  
 Primary ExaminerRobert G. Nilson [57] ABSTRACT A fluid valve operative based on a pressure differential through the utilization of different size pressure receiving piston faces. A first fluid, through pressure on an enlarged piston face, maintains a valve spool so shifted as to allow for a through passage of a second fluid. Upon a blocking of the first fluid, the second fluid, acting on a relatively smaller valve surface, actuates the valve and blocks through passage of the second fluid. The shifting of the valve presents yet a smaller pressure receiving face to the first fluid which, in conjunction with an exhaust port, provides a fail safe lock out requiring manual resetting of the relay.  
 13 Claims, 3 Drawing Figures Bleed Parr Aclualor Supp y High Low P170! Can/r0! Fluid pp y PNEUMATIC RELAY The present invention is generally concerned with pneumatic relays or fluid valves of the type utilized in conjunction with an automatic actuator for a gas or oil well line to cause the actuator to shut the well in should the pneumatic supply be blocked for any reason.  
  More particularly, the invention is concerned with a relay which operates solely on pressure differential, utilizing only a single moving part so as to provide a simple and trouble free unit which is unique in both structure and operation.  
  In conjunction with the above, the relay or valve incorporates a pressure controlled lock out which is fail safe in operation, particularly when compared to the more conventional spring-operated pin lock out devices which operate erratically and frequently fail under actual operating conditions.  
  Basically, the relay or valve of the invention is installed upstream of an automatic actuator and includes an elongated valve member longitudinally shiftable within a valve body basically between a first position allowing through passage of actuator fluid from a supply to the actuator, and a second position closing off the actuator supply and bleeding the actuator itself. Movement of the valve member is controlled basically by the presence or absence of a control fluid pressure in conjunction with different pressure receiving areas on the selectively exposed valve member or piston faces.  
  These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout.  
  FIG. 1 is a vertical cross-sectional view through the relay of the invention positioned within a schematically illustrated system;  
  FIG. 2 is a similar cross-sectional view of the relay with the valve member shifted to a flow terminating position; and  
  FIG. 3 is a partial sectional view illustrating the safety lockout concept of the invention.  
  Referring now more specifically to the drawings, reference numeral is used to generally designate the relay or valve comprising the invention. As will be appreciated from FIG. 1, the relay, in the contemplated environment, will be positioned on the upstream side of an automatic actuator 12 utilized to shut in a gas or oil well should the pneumatic supply be blocked for any reason.  
  The relay 10 itself includes an elongated body 14 having a central bore 16 therethrough which slidably receives the,valve member 18.  
  The valve member 18 projects beyond one end of the body 14 and is provided with a manipulating head or handle 20 thereon, an appropriate sealing ring 22 precluding the escape of fluid from the bore 16 at this first end of the body 14.  
  A fluid bleed port 24 is provided in communication with the bore 16 inward of the first end of the body 14. An outlet port 26, which communicates with the actuator 12, is provided inward of the bleed port 24 and also communicates with the central bore 16. An actuator fluid inlet port 28 is provided inward of the outlet port 26 and communicates the actuator fluid supply 30 with the relay 10. Finally, an exhaust port 32 is provided inward of the inlet port 28. The second end of the body 14 is closed by a plug 34 which has a small control fluid inlet port 36 therein communicating with a relatively small cylindrical valve seat 38 incorporating an O-ring seal 40.  
  The valve member 18 is provided with a first bore wall engaging O-ring seal 42 peripherally thereabout at a point selectively shiftable from between the bleed port 24 and outlet port 26, so as to allow for a through passage of the actuator fluid from the inlet 28 to the outlet 26 and actuator 12, and a second inwardly shifted position between the inlet 28 and the outlet 26 precluding flow therebetween while opening communication between the outlet 26 and bleed port 24 for a bleeding of the fluid from the actuator 12.  
  Immediately below or inward of the inlet port 28, the bore 16 is cylindrically enlarged, as indicated by reference numeral 44, the exhaust port 32 communicating with this enlarged bore portion 44 at the end thereof remote from the inlet port 28.  
  That portion of the valve member 18 within the enlarged bore portion 44, is also cylindrically enlarged as indicated by reference numeral 46, presenting an enlarged piston or pressure receiving face 48 directed toward the intake port 28 with an appropriate bore wall engaging O-ring seal 50 provided peripherally thereabout inward of the piston face 48.  
  The bore 16, below the exhaust port 32, or toward the second end of the valve body 14, is again cylindrically outwardly enlarged, as indicated by reference numeral 52. The valve member 18 is similarly enlarged, presenting a substantially greater piston face or pressure receiving face 54 directed toward the second end of the valve body 14 and the control fluid inlet 36. This further enlarged or piston portion of the valve member 18 also carries a peripheral sealing ring 56 which engages the wall of the bore portion 52. The bore 16 terminutes, immediately inward of the valve seat 38, in a further slightly enlarged portion 58 into which the last mentioned enlarged piston portion of the valve member 18 moves, breaking the sealed engagement of the sealing ring 56 with the bore wall as will be readily appreciated from FIGS. 2 and 3. The extreme end of the valve member 18 is provided with a greatly reduced cylindrical end portion 60 which seats within the end valve seat 38 into sealing engagement with the sealing ring 40 provided therein.  
  It is contemplated that the actuator fluid be supplied at a pressure of pounds while the control fluid be supplied at a pressure of approximately 30 pounds. In operation, assuming the manually set position of FIG. I, the pressure of the control fluid on the enlarged piston or pressure receiving face 54 is sufficient so as to retain the valve member 18 in its extended position as illustrated in FIG. 1, providing a through passage for the actuator fluid from the supply to the actuator, the piston face 48 seating against the shoulder defined between the main bore portion and the first enlarged bore portion 44. With the pressure receiving face 48 seated against the bore defined shoulder, it will be appreciated that the surface presented to the greater actuator fluid pressure is substantially reduced with the difference between the area of this face and the area of the face 54 receiving the control fluid pressure being specifically sized so as to result in a greater axial pressure on the face 54 and retention of the valve member 18 in the position of FIG. 1. It will be noted that in this position, the seal 42 closes off the bleed port 24 from both the inlet and outlet ports.  
  Should the control fluid be blocked, or the pressure thereof substantially reduced for any reason, the pressure on the face 54 is immediately decreased and the now greater pressure on the face 48 moves the valve member 18 inwardly, seating the reduced area end valve portion 60 within the valve seat 38 and at the same time closing communication between the inlet port 28 and the outlet port 26 so as to terminate flow to the actuator while at the same time opening communication between the outlet port 26 and the bleed port 24 so as to bleed the actuator pressure out of the relay l and, through the automatic operation of the actuator, cause the gas or oil well to shut in.  
  Once the relay has closed, it is essential that it not reopen until the malfunction which caused the initial closing be corrected. In other words, it is extremely important that the relay remain closed until specifically manually reset, regardless of reinstitution of the initially controlling pressures. In effecting this, it will be noted that with the valve portion 60 seated within the valve seat 38 over the small inlet port 36, only an extremely small pressure receiving surface is presented even should the original control fluid pressure return, this surface being substantially less than the surface 48 now fully presented to the substantially greater actuator fluid pressure as will be readily appreciated from FIG. 2, thereby avoiding substantially any possibility of the valve member 18 shifting to its activated position of FIG. 1.  
  As yet a further safeguard, and in order to make the relay fail safe in operation, provision is also made for a situation wherein the actuator fluid pressure is lost in conjunction with a restoration of the control fluid pressure. Such an unusual circumstance would normally result in a return of the valve member 18. However, the reduced size of the control fluid inlet port 36, in conjunction with the enlarged exhaust port 32 and the fluid passing space about the largest lower valve member portion provided by the enlarged bore portion 58 provides for a direct exhausting of any entering control fluid subsequent to a movement of the valve member 18 sufficiently so as to break the seal between the valve member portion 60 and the seal within its seat 38. The relative sizes of the exhaust port 32, inlet port 36 and fluid path suggested by the arrows in FIG. 3 is obviously to be such as to provide for a complete exhausting of any fluid pressure which might be produced in a situation as just described whereby a further closing movement of the valve member 18 is specifically precluded. In this manner, a positive lock-out is provided without requiring any mechanical latches, springs, lockpins or the like with the lock-out being substantially fail safe in operation.  
  From the foregoing, it should be appreciated that a highly unique pneumatic relay or fluid valve has been defined. This valve incorporates only a single moving part yet provides for a complete control, including a lock-out feature which accommodates any foreseeable circumstance effectively and simply without in anyway affecting the manual resetting of the relay.  
  The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.  
 what is claimed as new is as follows:  
  1. A valve comprising a valve body, an elongated bore within said body, a first fluid inlet port, an outlet port, a bleed port, a second fluid inlet port, a valve member slidable within said bore, said valve member presenting a first pressure surface on said valve member exposed to said first fluid inlet port, a second pressure surface on said valve member exposed to said second fluid inlet port, said valve being selectively shiftable between a first position allowing communication between the first fluid inlet port and the outlet port and precluding communication between the outlet port and the bleed port, and a second position allowing communication between said outlet port and said bleed port and precluding communication between said first fluid inlet port and said outlet port, a greater total force on said second pressure surface than on said first pressure surface maintaining said valve member in said first position, a greater total force on said first pressure surface than on said second pressure surface moving said valve to said second position, and means for effectively precluiding fluid pressure supplied said valve through said second fluid inlet port from moving said valve from said second position to said first position, said precluding means including a) an exhaust port in fluid communication with said second fluid inlet port only when said valve member is in a further position intermediate said first and second positions, and b) seal means preventing fluid communication between said exhaust port and said second fluid inlet port when said valve member is in said first and second positions.  
  2. A valve comprising a valve body, an elongated bore within said body, a first fluid inlet port, an outlet port, a bleed port, a second fluid inlet port, a valve member slidable within said bore, said valve member presenting a first fluid pressure surface on said valve member exposed to said first fluid inlet port, a second fluid pressure surface on said valve member exposed to said second fluid inlet port, said valve member being selectively shiftable between a first position allowing communication between the first fluid inlet port and the outlet port and precluding communication between the outlet port and the bleed port, and a second position allowing communication between said outlet port and said bleed port and precluding communication between said first fluid inlet port and said outlet port, a greater total force on said second pressure surface than on said first pressure surface maintaining said valve in said first position, a greater total force on said first pressure surface than on said second pressure surface moving said valve to said second position, a valve seat about said second fluid inlet port, said valve member including a portion thereon receivable within said seat to close said second fluid inlet port upon movement of the valve member from the first position thereof to the second position, and an exhaust port selectively communicated with said second fluid inlet port when said valve member isin a position intermediate said first and said second position.  
  3. The valve of claim 2 wherein said second pressure surface is of a substantially greater area than said first pressure surface.  
  4. The valve of claim 3 wherein said seat received valve portion presents a pressure receiving face directed toward said second fluid inlet port which has a substantially smaller area than said first pressure surface.  
  5. The valve of claim 4 wherein said valve member projects outwardly beyond a first end of said valve body for a manual gripping and manipulation thereof.  
  6. The valve of claim 5 wherein said second fluid inlet port is defined in the second end of said body, said bore and said valve member extending longitudinally through said body between the first and second ends thereof.  
  7. The valve of claim 6 wherein said outlet port is laterally directed through said body in inwardly spaced relation to said first end, said first inlet fluid port being laterally directed through said body in inwardly spaced relation to said outlet port.  
  8. The valve of claim 7 wherein said bleed port is laterally directed through said body between said first end and said outlet port.  
  9. The valve of claim 8 wherein said valve member includes a first bore engaging seal which, in the first position of the valve member, is orientated between the outlet port and the bleed port, and in the second position of the valve member is orientated between the outlet port and the first fluid inlet port.  
 10. The valve of claim 9 wherein said exhaust port is laterally directed through said body between the second end of the valve body and the first fluid inlet port.  
  11. The valve of claim 10 wherein said first pressure receiving surface on the valve member is orientated between the first fluid inlet port and the exhaust port, and bore engaging seal means about said valve member at said first pressure receiving surface.  
  12. The valve of claim 11 wherein said second pressure receiving surface on said valve member is orientated between the exhaust port and the second fluid inlet port, and bore engaging seal means about said valve member at said second pressure receiving surface.  
  13. The valve of claim 12 wherein said bore is of a constant diameter, engageable by the first bore engaging seal, between the first end of the body and a point just beyond the first fluid inlet port, said bore subsequently being enlarged to a point just beyond the exhaust port and sealingly engaged by the seal at the first pressure surface, said bore being further enlarged beyond the exhaust port and sealingly engaged by the seal at the second pressure surface, said bore, inward of the second fluid inlet port, being of a diameter greater than that of the second pressure surface and seal thereabout so as to selectively provide a fluid passage from the second fluid inlet port to the exhaust port.