Abstract:
A valve actuation mechanism has a plurality of links. Each link has a proximal end and distal end, and the links are disposed adjacent a valve member. The actuation mechanism also has at least one roller connected to the distal ends of at least two links. The roller contacts a surface of the valve member. In addition, at least one pivot for each link is present in the valve, wherein each pivot is positioned on the proximal end of each of the plurality of links.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims priority as a divisional application under 35 U.S.C. §121 of earlier filed application Ser. No. 13/314,852, entitled “HIGH RATE DISCHARGE (HRD) VALVE OPENING MECHANISM FOR A FIRE AND EXPLOSION PROTECTION” and filed on Dec. 8, 2011, which is hereby incorporated by reference. 
    
    
     BACKGROUND 
     This invention relates to a method of and apparatus for the discharge of one or more fire extinguishing agent(s). More particularly, the invention relates to a valve opening mechanism suited to the rapid discharge of fire extinguishing agent(s) and other high mass flow applications. 
     The invention refers to an apparatus used to rapidly disperse extinguishing agents within a confined space such as the crew compartment of a military vehicle following a fire or explosion event. These automatic fire extinguishing systems (AFES) are deployed after the event has been detected, typically using high speed infrared (IR) and/or ultra violet (UV) sensors. The systems comprise a cylinder filled with extinguishing agent, a fast acting valve and nozzle which enables rapid and efficient deployment of agent throughout the vehicle. 
     The rapid discharge of a fire extinguishing agent into confined areas of vehicles subsequent to an incident (such as a fuel explosion) is known to suppress the adverse effects experienced by the personnel within the vehicle to survivable levels. Some of the criteria used to determine a survivable event include extinguishing the flame and preventing re-flashing; a reduction in temperature to prevent greater than second degree burns; and the realization of safe levels (i.e. levels up to which personnel can continue to carry out their duties) of overpressure, acid gas, oxygen and concentration of fire extinguishing agent within the vehicle. 
     A known apparatus for fire extinguishing in such circumstances comprises a generally cylindrical canister which contains a fire extinguishing agent which is pressurized by a gas such as nitrogen. The fire extinguishant agent must be applied rapidly. The outlet for the extinguishant from the canister is typically positioned at the base of the cylinder. A high rate discharge (HRD) valve is operated to allow the discharge of the extinguishing agent. The opening of the valve allows the nitrogen to expand, pushing the extinguishant between it and the valve out through the valve. The orientation of the canister and the location of the outlet in the cylinder allow a high proportion of the extinguishing agent to be discharged rapidly (because the extinguishing agent will be pushed out of the outlet by the nitrogen adjacent the extinguishing agent). 
     Existing HRD valves, following an actuation, are normally re-furbished away from the vehicle prior to re-use. In certain field conditions this causes logistical and cost issues as both the return of used suppressors and the supply of new or re-furbished hardware to the vehicle is required. In an attempt to minimize this inconvenience, a new design of the HRD valve is being disclosed that can, if required, be disposed of rather than re-furbished. The proposed modified valve may incorporate some common features to the existing valve such as outlet and pressure gauge locations but maintain system efficacy against the fire/explosion challenges. 
     SUMMARY 
     In one embodiment, a valve actuation mechanism has a plurality of links. Each link has a proximal end and distal end, and the links are disposed adjacent a valve member. The actuation mechanism also has at least one roller connected to the distal ends of at least two links. The roller contacts a surface of the valve member. In addition, at least one pivot for each link is present in the valve, wherein each pivot is positioned on the proximal end of each of the plurality of links. 
     In another embodiment, a high speed valve has a valve body having a flow passage therethrough and a poppet disposed within the valve body. The poppet is movable between a first position in which the poppet blocks the flow passage and a second position. The poppet containing a piston connected to a stem at a proximal end of the stem. The valve also has a pivotal link actuation mechanism adjacent a distal end of the stem. 
     In yet another embodiment, a fire suppression system has a pressure container for holding a fire suppression material that is connected to a high speed valve. The high speed valve has a valve body having a flow passage therethrough and a poppet disposed within the valve body. The poppet is movable between a first position in which the poppet blocks the flow passage and a second position. The poppet containing a piston connected to a stem at a proximal end of the stem. The valve also has a pivotal link actuation mechanism adjacent a distal end of the stem. The system also has a conduit connected to the flow passage of the valve, a nozzle for dispersing the fire suppression material upon opening of the high speed valve. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of prior art apparatus for the discharge of a fire extinguishing agent. 
         FIG. 2  is a perspective view of a prior art high rate discharge (HRD) valve. 
         FIG. 3A  is a cross-sectional view of the prior art HRD valve in the closed position. 
         FIG. 3B  is a cross-sectional view of the prior art HRD valve in the open position. 
         FIG. 4  is a perspective view of an HRD valve with a pivotal-link actuation mechanism. 
         FIG. 5  is a cross-sectional view of the HRD valve with pivotal-link actuation mechanism. 
         FIG. 6  is an elevation view of the pivotal link actuation mechanism. 
         FIG. 7  is a perspective view of another embodiment of an HRD valve. 
         FIG. 8  is another perspective view of the HRD valve. 
         FIG. 9  is an elevation view of another embodiment of the pivotal-link actuation mechanism. 
         FIG. 10  is a cross-sectional view of yet another embodiment of the HRD valve. 
     
    
    
     DETAILED DESCRIPTION 
     A prior art apparatus  11  for the discharge of a fire extinguishing agent is shown in  FIGS. 1-3B . Referring to  FIG. 1 , apparatus  11  comprises a generally cylindrical canister  12  and a releasing mechanism  13 , such as a valve assembly  14  including high rate discharge (HRD) valve  15 . The releasing mechanism  13  is opened by solenoid actuator  16 . A predetermined mass of fire extinguishing agent is added to the canister  12 , which is then super-pressurized with nitrogen. Canister  12  is made from steel or a similarly high strength, rigid material to contain the pressurized extinguishing agent. 
     When the releasing mechanism  13  is opened the fire extinguishing agent discharges from the canister  12  in a fraction of a second. Canister  12  is usually fitted vertically (that is with its longitudinal axis extending vertically), or as close to vertical as possible, within an enclosed or confined area of a vehicle. In order for the fire extinguishing agent to be distributed homogenously within the confined area without adversely impacting the personnel or equipment contained therein, an outlet nozzle  17  needs to be extended to the highest point thereof, such as where the walls meet the roof. This is achieved in the apparatus  11  by connecting the nozzle  17  to the releasing mechanism  13  via conduit  18 , such an appropriate length of hose or pipe. 
     The vertical orientation of the canister  12  allows releasing mechanism  13  at the outlet of canister  12  to be located at the lowest point. In one embodiment, the fire extinguishant lies at the base of canister  12  (due to its relatively high density), with the nitrogen or a similar fluid pressurizing the space above. When the releasing mechanism  13  is opened, the pressurizing fluid expands and rapidly forces the extinguishant through HRD valve  15 , along conduit  18  and out of nozzle  17 . 
     When the fire extinguishing agent is super-pressurized by pressurized fluid within canister  12 , a proportion of the fluid dissolves into the fire extinguishant. When HRD valve  15  is operated to deploy the fire extinguishant agent, the rapid expansion of gas dissolved within the fire extinguishing agent causes turbulence within canister  12 , which forms a two phase mixture of liquid extinguishing agent and pressurizing fluid, and a foam or mousse is formed. 
       FIG. 2  is a perspective view of a prior art high rate discharge (HRD) valve  15  of valve assembly  14  that also includes release mechanism  13  and solenoid  16 . Valve  15  contains hollow body  20  with an elongate bore on a vertical axis that terminates with an opening that forms inlet  22 . Hollow body  20  has an enlarged central cavity (as seen in  FIGS. 3A and 3B ) that communicates laterally with discharge outlet  24 . The body of valve  15  is constructed from a metal alloy, or similarly rigid material. Valve  15  also contains mechanical override  26 , as well as solenoid  16  for actuating the internal regulating mechanisms of valve  15 . 
       FIGS. 3A and 3B  illustrate the internal workings of valve  15 . The main operating and regulating mechanism of valve  15  is poppet  30 . Poppet  30  is used to close the entrance to an opening in the body of valve  15 . Poppet  30  contains a piston  31  at proximate end  34 , connected to stem  35  that terminates at distal end  36  adjacent actuating mechanisms, such as mechanical override release mechanism  13  and solenoid  16 . Poppet  30  is constructed from a material the same as or similar to that of body  20  of valve  15 . Poppet  30  and stem  35  may be of various geometries, such as circular, oval, or polygonal in cross section so long as they match corresponding valve structures, such as the bore opening of inlet  22 . In one embodiment, poppet  30  is generally cylindrical, as is stem  35  that is centrally aligned with poppet  30 . 
     One or more annular grooves in piston  31  contain o-rings  32  which compress against the bore of valve  15 , providing a seal. O-rings  32  are fabricated from rubber, or a similar elastomeric polymer capable of creating an air-tight seal between poppet  30  and body  20 . Pressure inside canister  12  (illustrated in  FIG. 1 ) pushes against proximate end  34  of poppet  30 , forcing poppet  30  upward while constraining seals  32  against inlet  22  and canister  12 . Once poppet  30  is released, pressurized fluid contained inside canister  12  moves poppet  30  allowing the fluid to escape through outlet  24 . An elastomeric bumper  38  quiets the operation and prevents damage to poppet  30  and valve body  20 . Following the actuation of the valve via the release mechanism, typically a collet connected to solenoid  16  with mechanical override  26  consisting of a linkage assembly, poppet  30  slides to the open position allowing pressurized fluid, such as a fire extinguishant, to flow out of outlet  24 . The use of this common valve body  20  and poppet  30  arrangement allows for high mass flow rates through the valve  15 . 
       FIGS. 4 to 10  illustrate novel release mechanisms for valve  15 .  FIG. 4  is a perspective view of HRD valve  15  with a pivotal-link actuation mechanism  40 , and  FIG. 5  is a cross-sectional view of HRD valve  15  with pivotal-link actuation mechanism  40 . Valve  15  contains body  20  with a hollow cavity creating communication between inlet  22  and outlet  24 , poppet  30  with piston  31 , o-rings  32 , and stem  35 , and bumper  38  that have all been previously described. Poppet  30  is restrained by pivotal link actuation mechanism  40 , which has links  42   a - 42   d , rollers  44   a  and  44   b , and pivots  46   a - 46   b . In the embodiment illustrated, links are flat plate structures with rounded tops and bottoms, and are made from metal. The top and bottom of links  42  contain holes that allow for the attachment of rollers  44  between adjacent links, as well as attachment to pivots  46 . Rollers  44  are cylindrical metal rods that extend between adjacent links and are capable of rotation therebetween, forming what is a structure similar to a roller chain. Pivots  46  are short pieced of metal rods attached to body  20  of valve  15 . In alternate embodiments, pivots may be machined directly into body  20  during manufacture of valve  15 . In the closed position, poppet  30  is constrained vertically by the sets of pivoting links  42  and rollers  44  that contact top surface  48  of stem  35 . Links  42  also contact each other in the over-center position. Gap  49  in body  20  of valve  15  allows for the movement of pivotal-link actuation mechanism  40 . Gap  49  is a cutout in body  20  that will vary in dimension with differing embodiments, and will be dependent on space requirements for actuation of pivotal-link actuation mechanism  40 . 
     For the links to rotate and allow the roller to roll off the edge of the stem  35  (and thus allow movement of poppet  30 ), there is a slight vertical displacement given by Y=(r/COS θ)−r. The mechanical advantage is extremely high at a small angle, so a small horizontal force can overcome a very high vertical force. Besides the forces required to move poppet  30 , the horizontal force applied to rollers  44  will also have to overcome the drag created by the force against the roller axle, and a small amount of force from pivots  46 .  FIG. 6  illustrates pivotal link actuation mechanism  40  in operation where the links have been separated, i.e. pivoted, to a point close to allow stem  35  vertical motion. 
       FIG. 7  is a perspective view of another embodiment of pivotal link actuation mechanism  40  for HRD valve  15 . As previously described, poppet  30  is restrained by pivotal link actuation mechanism  40 , which has links  42 , rollers  44 , and pivots  46  (not shown in this view). Stem  35  contains wedge  50  on the exterior of distal end  36 , and an electrically actuated rod  52  contained within the interior that acts as a protractor pin. In the embodiment illustrated, links  46  are pushed apart from the center of stem  35  using wedge  50 , which is a taper on the pin of stem  35 . Wedge  50 , along with rod  52  and the electric initiator  54 , are mounted below rollers  44  within the body of the poppet  30 . On actuation, the electric protractor forces rod  52  out. Typical forces from such devices vary from 1000 N to around 5000 N, though higher and lower values can be provided. In the embodiment illustrated, wedge  50  has two 20° slopes. In an alternate embodiment, distal end  36  of stem  35  is generally conical in shape creating approximately a 20° slope for a portion of stem  35 . When combined with the force and linear movement from rod  52 , rollers  44  are pushed over the vertical edge of stem  35 , which allows poppet  30  to move to the open position. The angle of wedge  50  could be optimized depending on the force and linear motion provided by the actuation device used to open valve  15 . This type of operation would work just as well if wedge  50  was used to force links  42  open from the top, but this would also increase the overall space claim of valve  15 . 
       FIG. 8  is a perspective view of another embodiment of HRD valve  15 . Due to normal manufacturing tolerances, one of the two links  42   a  or  42   b  will likely be slightly shorter than the other, so the shorter link will take the majority of the load. Poppet  30  can tip slightly to align with the mismatched links, but the tipping may cause additional drag, as well as cause uneven pressure on o-rings  32 . The embodiment of illustrated in  FIG. 8  features a moving connection mount rocker  56  that carries both links  42   a  and  42   b . Rocker  56  is constrained vertically by backing plate  58 . Tapers on both sides of backing plate  58  allow the connection containing rocker  56  to rotate or swing slightly to accommodate mismatched links  42   a  and  42   b —assuring that each link carries equal loads. 
       FIG. 9  is an elevation view of another embodiment of pivotal link actuation mechanism  40 . In the embodiment illustrated, cut outs  60   a  and  60   b  are located just below rollers  46   a  and  46   b  on both links  42   a  and  42   b . In the closed position, flat areas  62   a  and  62   b  of cut outs  60   a  and  60   b  are used to hold poppet  30  in place. A protractor  64  is mounted horizontally within the valve assembly, which on actuation pushes the links  42  apart to the over vertical position and allows poppet  30  to be displaces to open valve  15 . Angled portions  66   a  and  66   b  of cut outs  60   a  and  60   b  allow for stem  35  to clear pivotal link actuation mechanism  40  with minimal rotation of links  46  about pivot points  44 . Protractor  64  may be an electronically actuated pyrotechnic device, such as a Metron™ actuator. In one embodiment, a groove  65  is contained within one of the links to allow contact with the actuation mechanism, such as a rod or actuation pin, from protractor  64 . The horizontal movement of protractor  64  along with cut outs  62  in links  46  provides a more compact design in terms of the overall valve space envelope required for pivotal link actuation mechanism  40 . 
       FIG. 10  is a cross-sectional view of yet another embodiment of the HRD valve  15  with pivotal link actuation mechanism  40 . As previously described, poppet  30  is restrained by pivotal link actuation mechanism  40 , which has links  42 , rollers  44 , and pivots  46 . Stem  35  contains wedge  50  on extending from the top of distal end  36 , which is connected to pressure actuated rod  72  contained within interior bore  74  of stem  35 . Seals  76  extend around the base portion of actuation rod  72  to create an airtight connection between bore  74  and rod  72 . Wedge  50  contains a different geometry than that previously described, and has pressure inlet  70  attached to the top thereof. In the embodiment shown in  FIG. 10 , pressure is communicated into wedge  50  assembly, the resultant force of which is used to drive wedge  50  up into the linkage assembly. The pressure could be communicated via the extinguisher itself (e.g. with a solenoid valve in line, or other actuation device), or via a separate pressure vessel or canister. An external pressurized canister could be used to operate one or several extinguishers containing the aforementioned and described pivotal link actuation mechanism  40  illustrated in  FIG. 10 . Optionally, a spring mechanism to store the required energy to operate wedge  50  could be provided that would push rod  72  upward to release poppet  30 . 
     While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.