Patent Description:
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. Such a system is described in <CIT> in which a system for controlling with safety the transfer or control of high pressure fluids from a container for use as to an inflatable escape slide is described. The pressurised container houses a valve mechanisms which includes a rupturable membrane and a lower surface of the membrane support element which supports the rupturable membrane. Movement of the membrane support element causes rupture of the membrane and allows pressurised fluid to travel from the pressurised container through a plurality of holes and out of the system. 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.

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 valve body comprises 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 at least one gas supply passage are formed through the dividing wall. 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, when the membrane support element is in the retracted position, the pocket is defined by the bottom surface of the membrane support element and the portion of the surface defining the bore that extends between the intersection of the bore and the inlet chamber and the bottom surface of the membrane support element and the wall of the bore.

In embodiments of the above, the outlet chamber may have a larger diameter than the inlet chamber.

According to the invention the at least one gas passage has an inlet and an outlet, the inlet to the at least one gas passage being in a side wall of the inlet chamber and the outlet to the at least one gas passage being 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 as claimed in any of the claims <NUM>-<NUM>, 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.

An embodiment of the disclosure will now be described, by way of example only, with reference to the accompanying drawings in which:.

With reference to <FIG>, an inflation system <NUM> comprises a source <NUM> of high pressure gas (for example carbon dioxide), a pneumatic valve and a connector <NUM> 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 <NUM>.

In this embodiment, the source <NUM> of high pressure gas is a pressurised cylinder having a threaded neck <NUM> which receives the pneumatic valve.

The pneumatic valve comprises a valve body <NUM>. 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 <NUM> may be constructed from a plurality of components suitably joined together.

The valve body <NUM> comprises a threaded outer surface <NUM> for threaded engagement with the threaded neck <NUM> of the pressurised gas cylinder <NUM>. The valve body <NUM> further comprises an outer shoulder <NUM> which axially engages the upper end <NUM> of the threaded neck <NUM> of the pressurised gas cylinder <NUM>. A seal, for example an O-ring seal <NUM> is arranged between the valve body <NUM> and the threaded neck <NUM> of the pressurised gas cylinder <NUM> to prevent escape of pressurised gas from around the valve body <NUM>.

The valve body <NUM> further comprises a gas inlet <NUM> and a gas outlet <NUM>. The gas inlet <NUM> is arranged at the base <NUM> of a recess <NUM> provided in the bottom end <NUM> of the valve body <NUM>. A rupturable membrane <NUM> is retained in the base <NUM> of the recess <NUM> across the gas inlet <NUM> by means of a retaining ring <NUM> which is mounted, for example threadedly mounted or press fitted, into the recess <NUM>. The membrane <NUM> may be made from a material such as aluminium, as is known in the art. The radially outer portion <NUM> of the rupturable membrane <NUM> is clamped against the base <NUM> of the recess <NUM> by the retaining ring <NUM>.

The valve body <NUM> further comprises an inlet chamber <NUM> in fluid communication with the gas inlet <NUM> and an outlet chamber <NUM> in fluid communication with the gas outlet <NUM>. The inlet chamber <NUM> and outlet chamber <NUM> are separated by a dividing wall <NUM> which extends across an internal cavity <NUM> defined in the valve body <NUM>.

The dividing wall <NUM> is formed with a central bore <NUM> and with a plurality of gas supply passages <NUM> arranged around and bypassing the bore <NUM>. The gas supply passages <NUM> provide a gas flow path (indicated by the arrows in <FIG>) from the gas inlet <NUM> to the gas outlet <NUM>. In this embodiment, there are fourteen (<NUM>) gas supply passages <NUM> arranged about the bore <NUM>. The gas supply passages <NUM> are equi-spaced circumferentially about the bore <NUM>. In other embodiments, the number of gas supply passages <NUM> and their configuration may differ.

The number and configuration of the gas supply passages <NUM> should be sufficient to deliver the required flow of inflating gas through the valve. The total cross-sectional flow area of the gas supply passages <NUM> is advantageously greater than the cross-sectional area of the inlet <NUM>. This will avoid the gas supply passages <NUM> creating a restriction to the flow of gas from the inlet <NUM> to the outlet <NUM>.

As can be seen for example from <FIG>, the outlet chamber <NUM> has a larger diameter than the inlet chamber <NUM>. Accordingly, the gas supply passages <NUM> are angled outwardly from the inlet chamber <NUM> to the outlet chamber <NUM>.

Each gas supply passage <NUM> has an inlet <NUM> and an outlet <NUM>. The inlet <NUM> to the gas supply passage <NUM> is formed in a side wall <NUM> of the inlet chamber <NUM> and the outlet <NUM> to the gas supply passage <NUM> is formed in a bottom wall <NUM> of the outlet chamber <NUM>. Of course, the positions of the inlets <NUM> and outlets <NUM> may vary in other embodiments.

In this embodiment, each gas supply passage <NUM> extends adjacent the side wall <NUM> of the outlet chamber <NUM>. The gas supply passage <NUM> may, as shown be generally straight, although as shown, it may turn at its outlet <NUM> so as to direct the gas flow more tangentially to the side wall <NUM> of the outlet chamber <NUM>.

It will be noted that the inlet <NUM> each gas supply passage <NUM> is smaller than the central region <NUM> of the rupturable membrane <NUM> which will separate after operation of the valve. This will, as will be described further below, prevent the ruptured membrane <NUM> entering and potentially passing through the gas supply passage <NUM>.

The valve further comprises a membrane support element <NUM> which is slidably mounted within the valve body <NUM> for movement between a retracted position shown in <FIG> and an extended position shown in <FIG>. The membrane support element <NUM> has a cylindrical lower end <NUM> and a hollow upper end <NUM>.

As shown in <FIG>, in the extended position of the membrane support element <NUM>, the lower surface <NUM> of the lower end <NUM> of the membrane support element <NUM> engages the central region <NUM> of the rupturable membrane <NUM>. The lower end surface <NUM> of the membrane support element <NUM> may, as illustrated, be concavely dished in some embodiments. The lower end <NUM> of the membrane support element <NUM> is received with a sliding fit within the gas inlet <NUM>.

The lower end <NUM> of the membrane support element <NUM> slidably extends through the bore <NUM> formed in the dividing wall <NUM> of the valve body <NUM>. The upper end <NUM> of the membrane support element <NUM> is slidably received in an upper bore <NUM> of the valve body <NUM>. The upper end <NUM> of the membrane support element <NUM> is provided with a radially outwardly flange which is engageable with a shoulder formed atop the upper bore <NUM> of the valve body <NUM>, thereby limiting the downward motion of the membrane support element <NUM>. An annular plug <NUM> is mounted, for example threadedly mounted, in the upper end <NUM> of the upper bore <NUM>. The flange of the membrane support element <NUM> is also engageable with the plug <NUM> thereby limiting the upward motion of the membrane support element <NUM>.

An actuator <NUM> is slidably mounted within a bore defined in the hollow upper end <NUM> of the membrane support element <NUM>. A spring <NUM> is located between a shoulder <NUM> defined at the lower end <NUM> of the actuator <NUM> and the bottom <NUM> of the bore. The spring <NUM> biases the membrane support element <NUM> in a downward direction such that in the extended position, the flange of the membrane support element <NUM> engages the shoulder of the valve body <NUM> and positions the lower surface <NUM> of the membrane support element <NUM> in contact with, or closely adjacent to, the rupturable membrane <NUM>.

The actuator <NUM> is coupled at its upper end <NUM> to a control mechanism <NUM> which is operable to retract the actuator <NUM> when it is desired to operate the inflation system.

Referring to <FIG> and <FIG>, the control mechanism comprises a pivotally mounted retaining element <NUM> which, when the valve <NUM> is in its closed configuration, abuts the upper end <NUM> of the actuator <NUM>. The retaining element <NUM> is mounted in a housing <NUM> mounted atop the plug <NUM> in this embodiment. The retaining element <NUM> may, as shown, be spring loaded by a spring <NUM> so as to rotate in a direction away from the actuator <NUM>. The retaining element <NUM> is retained in its "closed" position as shown in <FIG> by a pivotally mounted, L-shaped release element <NUM> which, as shown in this embodiment, may have a roller <NUM> engaging an upper surface of the retaining element <NUM>. A lanyard (not shown) with a ball at one end is received in an opening <NUM> of the release element <NUM> and extends out through an opening <NUM> in the housing <NUM>. The lanyard may be pulled so as to rotate the release member <NUM> and thereby disengage roller <NUM> from the retaining element <NUM> allowing it to pivot under the force of the spring <NUM> and under the force applied by the actuator <NUM>, thereby allowing the actuator to move upwardly to the "open" position shown in <FIG>.

Having described the construction of the valve, its method of operation will now be described.

As discussed above, the valve is mounted in the neck <NUM> of a high pressure gas cylinder <NUM>. Typically the gas within the cylinder <NUM> will be at very high pressure, for example 3300psi. The valve is preassembled and mounted into the cylinder neck <NUM>. Gas is filled into the cylinder via a non-return filling valve <NUM> shown in <FIG> and <FIG> after the valve has been fitted. The non-return valve <NUM> is mounted in the valve body <NUM> which has a filling passage <NUM> which bypasses the gas supply passages <NUM> and bore <NUM>.

In the normal, inoperative condition of the valve, the actuator <NUM> and membrane support element <NUM> are arranged in their extended positions, as shown in <FIG> and <FIG>. In this condition, the central region <NUM> of the membrane <NUM>, which is subject to the high pressure of the gas in the cylinder <NUM>, will be pressed into firm contact with the bottom surface <NUM> of the membrane support element <NUM>. It is not necessary for the bottom surface <NUM> of the membrane support element <NUM> to touch the membrane <NUM> prior to assembly of the valve to the cylinder <NUM>. Provided the lower surface <NUM> is arranged closely adjacent to the membrane <NUM>, the membrane <NUM> may be deformed slightly into contact with the bottom surface <NUM> of the membrane support element <NUM> without rupturing the membrane <NUM>. The downward force exerted on the membrane support element <NUM> by the actuator <NUM> and spring <NUM> counteracts the upward force exerted on the membrane <NUM> by the high pressure gas, thereby preventing the membrane <NUM> rupturing. In this condition, there is no flow from the cylinder <NUM> into the valve.

When it is desired to initiate inflation of the device, the control mechanism <NUM> is operated, by pulling on its lanyard to release the actuator <NUM> and allow it to retract to the position shown in <FIG> and <FIG>. Retraction of the actuator <NUM> removes or reduces the downward force exerted on the membrane support element <NUM>, such that the force the membrane support element <NUM> exerts on the membrane <NUM> is insufficient to counteract the upward force exerted on the membrane <NUM> by the high pressure gas in the gas cylinder <NUM>. The membrane <NUM> will then rupture and the central region <NUM> thereof detach from the radially outer portion <NUM> thereof. The high pressure gas escaping from the gas cylinder <NUM> continues to press the central region <NUM> of the membrane <NUM> against the bottom surface <NUM> of the membrane support element <NUM>, meaning that the detached central region <NUM> will move upwardly with the membrane support element <NUM>. The concave shape of the bottom surface <NUM> of the membrane support element <NUM> may assist in retention of the detached portion <NUM> on the membrane support element <NUM>.

The membrane support element <NUM> will move upwardly to the position shown in <FIG> and <FIG> in which the flange at the upper end <NUM> of the membrane support element <NUM> comes into contact with the plug <NUM>. In this position, as can be seen most clearly in <FIG>, the lower end <NUM> of the membrane support element <NUM> is still located within the bore <NUM> of the dividing wall <NUM>. The bottom surface <NUM> of the membrane support element <NUM> and the wall of the bore <NUM> define a pocket <NUM> for receiving the detached central region <NUM> of the membrane <NUM>. The detached region <NUM> of the membrane <NUM> will be pushed into the pocket <NUM> by the pressure of gas escaping from the cylinder <NUM>, so that the detached region <NUM> will be retained in the pocket <NUM>.

Retraction of the membrane support element <NUM> allows flow of inflating gas from the gas inlet <NUM> to the gas outlet <NUM> via the gas supply passages <NUM>. As discussed above, as the total flow area of the gas supply passages <NUM> advantageously may be greater than that of the gas inlet <NUM>, the gas supply passages <NUM> do not inhibit gas flow through the valve. In fact, the total flow area of the gas supply passages <NUM> may be significantly greater, for example <NUM>% greater than that of the gas inlet such that blockage of one or more gas supply passages <NUM> by the detached region <NUM> of the membrane <NUM> will not adversely affect the flow of gas through the valve.

Moreover, as the inlet <NUM> of each gas supply passage <NUM> may be smaller than the central region <NUM> of the rupturable membrane <NUM>, should for some reason the detached region <NUM> of the membrane <NUM> separate from the membrane support element <NUM>, it will not be able to pass through the gas supply passage <NUM> and flow further downstream where it might potentially cause a blockage or damage. The location of the lower end <NUM> of the membrane support element <NUM> in the bore <NUM> prevents the detached membrane region <NUM> from entering the gas flow path via that bore <NUM>.

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.

Claim 1:
A pneumatic valve for attachment to a source of high pressure gas, the pneumatic valve comprising:
a valve body (<NUM>) comprising a gas inlet (<NUM>) and a gas outlet (<NUM>);
a rupturable membrane (<NUM>) extending across the gas inlet (<NUM>);
a membrane support element (<NUM>) slidably supported in the valve body (<NUM>) for movement between an extended position and a retracted position, the membrane support element (<NUM>) having a lower end (<NUM>) engageable, in the extended position, with the rupturable membrane (<NUM>) to support the rupturable membrane (<NUM>) against rupture;
wherein the valve body (<NUM>) comprises a bore (<NUM>) through which the membrane support element (<NUM>) extends and one or more gas supply passages (<NUM>) bypassing the bore (<NUM>) for providing a gas flow path from the gas inlet (<NUM>) to the gas outlet (<NUM>);
the valve body (<NUM>) comprises an inlet chamber (<NUM>) in fluid communication with the gas inlet (<NUM>) and an outlet chamber (<NUM>) in fluid communication with the gas outlet (<NUM>), the inlet chamber (<NUM>) and outlet chamber (<NUM>) being separated by a dividing wall (<NUM>);
the bore (<NUM>) and at least one gas supply passage (<NUM>) are formed through the dividing wall (<NUM>); and
the membrane support element (<NUM>) being configured to be movable from the extended position to the retracted position to permit the rupturable membrane (<NUM>) to rupture under the pressure of the high pressure gas, the lower end (<NUM>) of the membrane support element (<NUM>) in the retracted position being positioned within the bore (<NUM>) whereby the lower end (<NUM>) of the membrane support element (<NUM>) and the bore (<NUM>) together form a pocket (<NUM>) for receiving a ruptured portion (<NUM>) of the rupturable membrane (<NUM>),
wherein at least one gas passage (<NUM>) has an inlet (<NUM>) and an outlet (<NUM>), the inlet (<NUM>) to the at least one gas passage (<NUM>) being in a side wall (<NUM>) of the inlet chamber (<NUM>), characterised in that the outlet (<NUM>) to the at least one gas passage (<NUM>) is in a bottom wall (<NUM>) of the outlet chamber (<NUM>).