Patent Publication Number: US-2021181770-A1

Title: Pneumatic valve with rupturable membrane

Description:
FOREIGN PRIORITY 
     This application claims priority to European Patent Application No. 19461615.7 filed Dec. 13, 2019, the entire contents of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a pneumatic valve, and in particular to a pneumatic valve having a rupturable membrane. Such valves may be used, for example, as inflation valves in inflation systems. 
     BACKGROUND 
     Pneumatic inflation valves are used in inflation systems that need to be inflated rapidly, such as those used in aircraft evacuation slides, inflatable dinghies and so on. The valve has a membrane which is ruptured to release high pressure inflating gas from a high pressure source into an inflation system. In some systems, the membrane is supported against rupture by a valve element which is released in order to allow the membrane to be ruptured by the pressure of gas from the inflation source. It is desirable that the ruptured membrane does not interfere with the supply of inflation gas to the device to be inflated. The present disclosure seeks to provide a pneumatic valve which mitigates this problem. 
     SUMMARY 
     From a first aspect, the disclosure provides a pneumatic valve for attachment to a source of high pressure gas. The pneumatic valve comprises a valve body which comprises a gas inlet and a gas outlet. A rupturable membrane extends across the gas inlet. A membrane support element is slidably supported in the valve body for movement between an extended position and a retracted position. The membrane support element has a lower end which is engageable, in the extended position, with the rupturable membrane to support the rupturable membrane against rupture. The valve body further comprises a bore through which the membrane support element extends and one or more gas supply passages bypassing the bore for providing a gas flow path from the gas inlet to the gas outlet. The membrane support element is configured to be movable from the extended position to the retracted position to permit the rupturable membrane to rupture under the pressure of the high pressure gas. The lower end of the membrane support element in the retracted position is positioned within the bore whereby the lower end of the membrane support element and the bore together form a pocket for receiving a ruptured portion of the rupturable membrane. 
     In embodiments of the above, the valve body may comprise a plurality of gas supply passages arranged around the bore. Optionally the gas supply passages may be circumferentially equi-spaced about the bore. 
     In embodiments of any of the above, the total cross sectional flow area of the at least one gas passage may be greater than the cross sectional flow area of the gas inlet. This reduces the possibility of the gas passage restricting flow from the gas inlet to the gas outlet. 
     In embodiments of any of the above, the valve body may comprise an inlet chamber in fluid communication with the gas inlet and an outlet chamber in fluid communication with the gas outlet, the inlet chamber and outlet chamber being separated by a dividing wall. The bore and the at least one gas supply passage may be formed through the dividing wall. 
     In embodiments of the above, the outlet chamber may have a larger diameter that the inlet chamber, and the at least one gas supply passage may be angled outwardly from the inlet chamber to the outlet chamber. 
     In embodiments of any of the above, the at least one gas passage may have an inlet and an outlet. The inlet to the at least one gas passage may be in a side wall of the inlet chamber and the outlet to the at least one gas passage may be in a bottom wall of the outlet chamber. 
     In embodiments of any of the above, the bottom surface of the membrane support element may be concavely dished. This may assist in retaining the ruptured membrane thereon. 
     In embodiments of any of the above, the valve may further comprise an actuator coupled to the membrane support element and retractable to permit retraction of the membrane support element. 
     The actuator may be retained in a position in which it engages the membrane support element by a retaining element which is releasable to allow the membrane support element to move from its extended position to its retracted position. 
     The retaining element may, in various embodiments be a pivotally mounted element. The retaining element may be spring biased towards the released position of the retaining element. 
     The retaining element may, in various embodiments, be released by a release element which may, for example, be pivotally mounted and which may, for example be released by a user pulling on a lanyard coupled to the release element. 
     In various embodiments, the actuator may be mounted within a bore of the membrane support element. 
     In embodiments of any of the above, the membrane support element may be resiliently biased towards the rupturable membrane. 
     In embodiments of any of the above, the valve body may comprise a stop with which the membrane support element is engageable in the retracted position. This may assist in accurately positioning the bottom end of the membrane support element within the bore. 
     In embodiments of any of the above, the valve body may comprise a stop with which the membrane support element is engageable in the extended position. This may assist in accurately positioning the bottom end of the membrane support element in contact with the rupturable membrane. 
     In embodiments of any of the above, the gas inlet may be arranged at the base of a recess provided in the valve body and the valve may further comprise an annular retaining ring mounted in the recess for retaining the membrane in the recess. 
     The disclosure also provides an inflation system comprising a source of inflation gas, for example a pressurised gas cylinder, and a pneumatic valve in accordance with the disclosure mounted in fluid communication with the source, for example to a neck of the pressurised gas cylinder. 
     The disclosure also provides a method of retaining a rupturable membrane in a pneumatic valve, comprising retracting a membrane support element through a bore to release the membrane, but maintaining a lower end of the membrane support element in the bore such that the ruptured membrane is received within and cannot pass through the bore. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       An embodiment of the disclosure will now be described, by way of example only, with reference to the accompanying drawings in which: 
         FIG. 1  shows a vertical cross section of an inflation system incorporating a pneumatic valve in accordance with the disclosure in an open configuration; 
         FIG. 2  shows a detail of the pneumatic valve illustrated in  FIG. 1 ; 
         FIG. 3  shows a further detail of the pneumatic valve illustrated in  FIG. 1 ; 
         FIG. 4  shows a further cross sectional view of the inflation system of  FIG. 1  taken along line A-A of  FIG. 1 , with the pneumatic valve in an open configuration; and 
         FIG. 5  shows a vertical cross sectional view of the inflation system of  FIG. 1  along the line A-A, but with the pneumatic valve in a closed configuration. 
     
    
    
     DETAILED DISCRIPTION 
     With reference to  FIG. 1 , an inflation system  2  comprises a source  4  of high pressure gas (for example carbon dioxide), a pneumatic valve  6  and a connector  8  for connecting to a device such as an evacuation slide which requires inflation. A pressure regulation valve (not shown) may be provided in or coupled to the connector  8 . 
     In this embodiment, the source  4  of high pressure gas is a pressurised cylinder having a threaded neck  10  which receives the pneumatic valve  6 . 
     The pneumatic valve  6  comprises a valve body  12 . In this embodiment, the valve body is a one-piece body which may be made, for example, by additive manufacturing or casting. Additive manufacturing is particularly advantageous as it will allow intricately shaped passages and features to be manufactured simply. In other embodiments, however, the valve body  12  may be constructed from a plurality of components suitably joined together. 
     The valve body  12  comprises a threaded outer surface  14  for threaded engagement with the threaded neck  10  of the pressurised gas cylinder  4 . The valve body  12  further comprises an outer shoulder  16  which axially engages the upper end  18  of the threaded neck  10  of the pressurised gas cylinder  4 . A seal, for example an O-ring seal  20  is arranged between the valve body  12  and the threaded neck  10  of the pressurised gas cylinder  4  to prevent escape of pressurised gas from around the valve body  12 . 
     The valve body  12  further comprises a gas inlet  22  and a gas outlet  24 . The gas inlet  22  is arranged at the base  26  of a recess  28  provided in the bottom end  30  of the valve body  12 . A rupturable membrane  32  is retained in the base  26  of the recess  28  across the gas inlet  22  by means of a retaining ring  34  which is mounted, for example threadedly mounted or press fitted, into the recess  28 . The membrane  32  may be made from a material such as aluminum, as is known in the art. The radially outer portion  35  of the rupturable membrane  32  is clamped against the base  26  of the recess  28  by the retaining ring  34 . 
     The valve body  12  further comprises an inlet chamber  38  in fluid communication with the gas inlet  22  and an outlet chamber  40  in fluid communication with the gas outlet  24 . The inlet chamber  36  and outlet chamber  38  are separated by a dividing wall  42  which extends across an internal cavity  44  defined in the valve body  12 . 
     The dividing wall  42  is formed with a central bore  46  and with a plurality of gas supply passages  48  arranged around and bypassing the bore  46 . The gas supply passages  48  provide a gas flow path (indicated by the arrows in  FIG. 3 ) from the gas inlet  22  to the gas outlet  24 . In this embodiment, there are fourteen (14) gas supply passages  48  arranged about the bore  46 . The gas supply passages  48  are equi-spaced circumferentially about the bore  46 . In other embodiments, the number of gas supply passages  48  and their configuration may differ. 
     The number and configuration of the gas supply passages  48  should be sufficient to deliver the required flow of inflating gas through the valve  6 . The total cross-sectional flow area of the gas supply passages  48  is advantageously greater than the cross-sectional area of the inlet  22 . This will avoid the gas supply passages  48  creating a restriction to the flow of gas from the inlet  22  to the outlet  24 . 
     As can be seen for example from  FIG. 2 , the outlet chamber  40  has a larger diameter than the inlet chamber  38 . Accordingly, the gas supply passages  48  are angled outwardly from the inlet chamber  38  to the outlet chamber  40 . 
     Each gas supply passage  48  has an inlet  50  and an outlet  52 . The inlet  50  to the gas supply passage  48  is formed in a side wall  54  of the inlet chamber  38  and the outlet  52  to the gas supply passage  48  is formed in a bottom wall  56  of the outlet chamber  40 . Of course, the positions of the inlets  50  and outlets  52  may vary in other embodiments. 
     In this embodiment, each gas supply passage  48  extends adjacent the side wall  58  of the outlet chamber  40 . The gas supply passage  48  may, as shown be generally straight, although as shown, it may turn at its outlet  52  so as to direct the gas flow more tangentially to the side wall  58  of the outlet chamber  40 . 
     It will be noted that the inlet  52  each gas supply passage  48  is smaller than the central region  60  of the rupturable membrane  32  which will separate after operation of the valve  6 . This will, as will be described further below, prevent the ruptured membrane  32  entering and potentially passing through the gas supply passage  48 . 
     The valve  2  further comprises a membrane support element  62  which is slidably mounted within the valve body  12  for movement between a retracted position shown in  FIG. 1  and an extended position shown in  FIG. 2 . The membrane support element  62  has a cylindrical lower end  64  and a hollow upper end  66 . 
     As shown in  FIG. 2 , in the extended position of the membrane support element  62 , the lower surface  68  of the lower end  64  of the membrane support element  62  engages the central region  60  of the rupturable membrane  32 . The lower end surface  68  of the membrane support element  62  may, as illustrated, be concavely dished in some embodiments. The lower end  64  of the membrane support element  62  is received with a sliding fit within the gas inlet  22 . 
     The lower end  64  of the membrane support element  62  slidably extends through the bore  46  formed in the dividing wall  42  of the valve body  12 . The upper end  66  of the membrane support element  62  is slidably received in an upper bore  70  of the valve body  12 . The upper end  66  of the membrane support element  62  is provided with a radially outwardly flange  72  which is engageable with a shoulder  74  formed atop the upper bore  70  of the valve body  12 , thereby limiting the downward motion of the membrane support element  62 . An annular plug  76  is mounted, for example threadedly mounted, in the upper end  78  of the upper bore  70 . The flange  72  of the membrane support element  62  is also engageable with the plug  76  thereby limiting the upward motion of the membrane support element  62 . 
     An actuator  78  is slidably mounted within a bore  80  defined in the hollow upper end  66  of the membrane support element  62 . A spring  82  is located between a shoulder  84  defined at the lower end  86  of the actuator  78  and the bottom  88  of the bore  80 . The spring  82  biases the membrane support element  62  in a downward direction such that in the extended position, the flange  72  of the membrane support element  62  engages the shoulder  74  of the valve body  12  and positions the lower surface  68  of the membrane support element  62  in contact with, or closely adjacent to, the rupturable membrane  32 . 
     The actuator  78  is coupled at its upper end  90  to a control mechanism  92  which is operable to retract the actuator  78  when it is desired to operate the inflation system. 
     Referring to  FIGS. 4 and 5 , the control mechanism comprises a pivotally mounted retaining element  94  which, when the valve  2  is in its closed configuration, abuts the upper end  96  of the actuator  78 . The retaining element  94  is mounted in a housing  98  mounted atop the plug  76  in this embodiment. The retaining element  94  may, as shown, be spring loaded by a spring  100  so as to rotate in a direction away from the actuator  78 . The retaining element  94  is retained in its “closed” position as shown in  FIG. 5  by a pivotally mounted, L-shaped release element  102  which, as shown in this embodiment, may have a roller  104  engaging an upper surface  106  of the retaining element  94 . A lanyard (not shown) with a ball at one end is received in an opening  108  of the release element  102  and extends out through an opening  110  in the housing  98 . The lanyard may be pulled so as to rotate the release member  102  and thereby disengage roller  104  from the retaining element  94  allowing it to pivot under the force of the spring  104  and under the force applied by the actuator  78 , thereby allowing the actuator to move upwardly to the “open” position shown in  FIG. 4 . 
     Having described the construction of the valve  6 , its method of operation will now be described. 
     As discussed above, the valve  6  is mounted in the neck  10  of a high pressure gas cylinder  4 . Typically the gas within the cylinder  4  will be at very high pressure, for example 3300 psi. The valve  6  is preassembled and mounted into the cylinder neck  10 . Gas is filled into the cylinder via a non-return filling valve  112  shown in  FIGS. 4 and 5  after the valve  6  has been fitted. The non-return valve  112  is mounted in the valve body  12  which has a filling passage  114  which bypasses the gas supply passages  48  and bore  46 . 
     In the normal, inoperative condition of the valve  6 , the actuator  78  and membrane support element  62  are arranged in their extended positions, as shown in  FIGS. 2 and 5 . In this condition, the central region  60  of the membrane  32 , which is subject to the high pressure of the gas in the cylinder  4 , will be pressed into firm contact with the bottom surface  68  of the membrane support element  62 . It is not necessary for the bottom surface  68  of the membrane support element  62  to touch the membrane  32  prior to assembly of the valve  6  to the cylinder  4 . Provided the lower surface  68  is arranged closely adjacent to the membrane  32 , the membrane  32  may be deformed slightly into contact with the bottom surface  68  of the membrane support element  62  without rupturing the membrane  32 . The downward force exerted on the membrane support element  62  by the actuator  78  and spring  82  counteracts the upward force exerted on the membrane  32  by the high pressure gas, thereby preventing the membrane  32  rupturing. In this condition, there is no flow from the cylinder  4  into the valve  6 . 
     When it is desired to initiate inflation of the device, the control mechanism  92  is operated, by pulling on its lanyard to release the actuator  78  and allow it to retract to the position shown in  FIGS. 1 and 4 . Retraction of the actuator  78  removes or reduces the downward force exerted on the membrane support element  62 , such that the force the membrane support element  62  exerts on the membrane  32  is insufficient to counteract the upward force exerted on the membrane  32  by the high pressure gas in the gas cylinder  4 . The membrane  32  will then rupture and the central region  60  thereof detach from the radially outer portion  35  thereof. The high pressure gas escaping from the gas cylinder  4  continues to press the central region  60  of the membrane  32  against the bottom surface  68  of the membrane support element  62 , meaning that the detached central region  60  will move upwardly with the membrane support element  62 . The concave shape of the bottom surface  68  of the membrane support element  62  may assist in retention of the detached portion  60  on the membrane support element  62 . 
     The membrane support element  62  will move upwardly to the position shown in  FIGS. 1 and 4  in which the flange  72  at the upper end  66  of the membrane support element  62  comes into contact with the plug  76 . In this position, as can be seen most clearly in  FIG. 1 , the lower end  64  of the membrane support element  62  is still located within the bore  46  of the dividing wall  42 . The bottom surface  68  of the membrane support element  62  and the wall of the bore  66  define a pocket  120  for receiving the detached central region  60  of the membrane  32 . The detached region  60  of the membrane  32  will be pushed into the pocket  120  by the pressure of gas escaping from the cylinder  4 , so that the detached region  60  will be retained in the pocket  120 . 
     Retraction of the membrane support element  62  allows flow of inflating gas from the gas inlet  22  to the gas outlet  24  via the gas supply passages  48 . As discussed above, as the total flow area of the gas supply passages  48  advantageously may be greater than that of the gas inlet  22 , the gas supply passages  48  do not inhibit gas flow through the valve  6 . In fact, the total flow area of the gas supply passages  48  may be significantly greater, for example 10% greater than that of the gas inlet such that blockage of one or more gas supply passages  48  by the detached region  60  of the membrane  32  will not adversely affect the flow of gas through the valve  6 . 
     Moreover, as the inlet  52  of each gas supply passage  48  may be smaller than the central region  60  of the rupturable membrane  32 , should for some reason the detached region  60  of the membrane  32  separate from the membrane support element  62 , it will not be able to pass through the gas supply passage  48  and flow further downstream where it might potentially cause a blockage or damage. The location of the lower end  64  of the membrane support element  62  in the bore  46  prevents the detached membrane region  60  from entering the gas flow path via that bore  46 . 
     It will be seen from the above that in its various embodiments, the disclosure provides a pneumatic valve for use in an inflation system incorporating a rupturable membrane which reduces the risk of the ruptured membrane passing through the valve and into the downstream flow where it may, for example, cause a blockage or damage. 
     It will be appreciated that the description is of a non-limiting embodiment of the disclosure and that modifications may be made thereto without departing from the scope of the disclosure.