EP3278006A1

EP3278006A1 - Low power failsafe valve

Info

Publication number: EP3278006A1
Application number: EP16712382.7A
Authority: EP
Inventors: Brian Jacobsen; Mark Hesketh; James YORKSHADES
Original assignee: Linde GmbH
Current assignee: Linde GmbH
Priority date: 2015-03-31
Filing date: 2016-03-31
Publication date: 2018-02-07
Also published as: GB201505481D0; WO2016156518A1

Abstract

A failsafe shut-off valve for a cylinder containing compressible fluid. The valve comprises a shuttle element moveable between an opening position and a closure position and being biased toward the closure position. When the shuttle element is in the closure position, it causes actuation of a restriction element to restrict flow of the compressible fluid through the valve. The valve also has a driving means configured so that, when activated, it provides a driving force to urge the shuttle element toward the opening position.

Description

LOW POWER FAILSAFE VALVE

FIELD OF THE INVENTION

The present invention relates to a failsafe shut-off valve for a cylinder containing compressible fluid. The valve contains a restriction element such as a shuttle that is urged toward an open configuration by a driving force to permit flow of compressible fluid through the valve. Upon interruption of that force (e.g. following from a cut-off of a power supply) the valve will close, thus providing a failsafe. The valve is configured such that the urging force required is very small, thus putting low power demands on the failsafe shut-off valve.

BACKGROUND OF THE INVENTION

The use of containers, typically cylinders, for storing and dispensing pressurised fluid is ubiquitous. Some notable examples include their use to store and dispense gases for medical purposes, for scientific research or for industrial applications. The cylinders may further be used to transport pressurised fluid between locations, either to be transferred to local storage for later use or to be extracted on demand from the cylinder at the point of use.

Although reference is made to a "cylinder", it will be understood that the invention is applicable broadly to all portable pressurised gas containers whether they are strictly in the form of a cylinder or not.

Such cylinders are used to supply gas for a range of applications including welding and cutting hoses and torches, gas packaging machines and laboratory equipment. Often, cylinders are used in hazardous conditions or to supply pressurised fluid that is considered to be hazardous. Consequently, there will be a risk associated with the use of such cylinders. In particular, should conditions occur in which continued use of the cylinder would pose a significant health and safety risk, it is often necessary to cease use of the cylinder entirely, and prevent the release of compressible fluid. A user can simply turn off the valve to prevent fluid release if that user detects dangerous conditions, and it is known to employ valves with construction that can be quickly shut off in the event of dangerous conditions. For example, in US Patent 4,793,379 a button-operated shut off valve is employed to allow a user to quickly shut off a valve in dangerous conditions.

However, it is often desired to provide a shut-off valve that operates as a failsafe to automatically shut off the valve should dangerous conditions be detected, without intervention of the user. A general and commonly employed failsafe mechanism includes an electromechanical actuator such as a solenoid charged by an electrical current, such as that described in US Patent 6,050,281 . The charged solenoid actuates an element to open and close the valve, thereby allowing and preventing release of fluid. Electrical current is provided to the solenoid to keep the valve open, and upon an interruption to the current, the solenoid will disengage and the valve shut off.

However, while valves employing such electromechanical actuators do provide a reliable failsafe, these valves generally require large amounts of energy to keep the valve open. This means that a valve using such actuators need to be provided with an external power supply such as a mains power supply to function as a failsafe. Thus, it is not practical to implement these existing failsafe designs on electrical valves that function on only a battery, as the power demands would be too high.

Some low-power failsafe valves exist, such as a valve provided to shut off upon detection of a high flow rate, such as in the valve employed in US Patent 7,708,028. However, this type of valve is only directed toward shut off in the specific condition of a high flow rate. Other failsafe valves reduced power consumption rely on external power sources, such as a capacitor charged closing mechanism, or an auxiliary energy source deactivating a latch upon failure, where the latch holds the valve open.

The present invention seeks to provide an alternative failsafe shut-off valve which provides various advantages over those of the prior art. In particular, the present invention provides a failsafe shut-off valve with very low power consumption, without the need to rely on an auxiliary power means.

SUMMARY OF THE INVENTION According to a first aspect of the present invention, there is provided a failsafe shut-off valve for a cylinder containing compressible fluid, the valve comprising a shuttle element moveable between an opening position and a closure position and being biased toward the closure position, wherein when the shuttle element is in the closure position, the shuttle element causes actuation of a restriction element of the valve to restrict flow of the compressible fluid through the valve; and a driving means configured such that when activated the driving means provides a driving force to urge the shuttle element toward the opening position. By driving the shuttle element with the driving means to actuate the restriction element instead of directly driving the restricting element, lower power consumption is required to provide a failsafe operation of a valve.

Advantageously, the failsafe shut-off valve further comprises a controller configured to provide a control signal to the driving means to activate the driving means. In this advantageous embodiment, a degree of flexibility can be provided to the operation of the shuttle element and therefore the failsafe shut-off valve, providing an advantage over fail-safe shut off valves known in the art.

Further advantageously, the bias provided to the shuttle element is such that in the absence of the driving force, a movement of the shuttle element is damped. This damping means that the shuttle element will not immediately revert to the closure position upon loss of power, but will do so at a small time later (e.g. five seconds). This allows for intermittent drop-outs in power to the driving means, meaning that the fail-safe is not triggered by brief unintentional drop out in the power supply that would not warrant a full valve shut down. The damping also provides for a further advantageous embodiment, wherein the control signal is provided to activate and deactivate the driving means at a driving frequency, the driving frequency greater than the reciprocal of the time required for the shuttle element to move from the open position to the closed position under the action of the bias. In this embodiment, the driving means can be intermittently deactivated without resulting in a shut off of the valve. This means that it is not necessary for a driving force to be applied at all times, thereby reducing the power required by the driving means to maintain operation of the valve. Even further advantageously, the opening position of the shuttle element is one of a plurality of opening positions of the shuttle element, wherein in each of the plurality of opening positions, the restriction element is provided to allow unrestricted flow of compressible fluid through the valve, and the driving frequency is greater than the time required for the shuttle element to move from a first opening position to a second opening position. In this embodiment, the failsafe shut off valve can operate in a low power consumption mode without the shuttle element moving from a configuration where fluid flow through the valve is restricted. This prevents any reduction in flow occurring as a result of

intermittently interrupting the driving means power supply.

In another advantageous embodiment, the failsafe shut-off valve comprises a valve stem, the valve stem comprising: a chamber with chamber pathway for fluid communication of the chamber with a first portion of a flow channel of the valve, the restriction element, the restriction element comprising a flow-through channel for passage of fluid from a second portion of the valve flow channel into the chamber, wherein the shut-off valve is configured such that when the shuttle element is in the closure position the chamber pathway is blocked, thereby isolating the chamber from the first portion of the flow channel such that the chamber is provided at the pressure of the second portion of the flow channel and resulting in a closure force on the restriction element to actuate the restriction element to restrict flow of the compressible fluid from the second portion of the flow channel to the first portion of the flow channel. In this embodiment, the force being provided to actuate the restriction element between open and closed configurations, to allow and prevent flow respectively, results from a pressure provided by the compressible fluid inside a cylinder to which the valve is attached. This is in contrast to fail-safe shut off valves known in the art where the force is provided by a driving means, which requires consumption of a large amount of power.

The actuation may be provided by a construction of the valve stem in an advantageous embodiment, where the restriction element comprises: a first surface provided inside the chamber and at the pressure inside the chamber; a second surface opposite the first surface, provided outside the chamber in the second portion of the flow channel and at the pressure of the second portion of the flow channel; wherein the second surface is smaller in surface area than the first surface, such that when the shuttle element is in the closure position and the first and second surface areas are provided at the pressure of the second portion of the flow channel, different pressure forces are provided at the first and second areas resulting in actuation of the restriction element.

Advantageously, the valve stem further comprises a stem biasing means configured to provide a force to the restriction element to oppose the closure force. This provides a biasing force to the restriction element to bias the restriction element to the open position when the above-identified difference in pressure forces is not sufficient to overcome the force provided by the stem biasing means. This ensures the valve is provided in the open position to permit fluid flow when the shuttle element is in an opening position.

Further advantageously, the driving means comprises an electromechanical actuator configured to be activated by the supply of electrical current. One such example is a solenoid configured to be charged by an electrical current. Such electromechanical actuators can be relied upon to be easily activated and deactivated upon application and removal of an electric current.

Further advantageously, the failsafe shut-off valve further comprises a shuttle biasing means such that the bias provided to the shuttle element comprises at least one of a mechanical bias and a viscous bias.

In a further advantageous embodiment, the damping to the shuttle element is provided by an electrical damping means, the electrical damping means comprising a magnet attached to the shuttle element and a coil provided around the shuttle element, such that a movement of the shuttle element induces a current in the coil to produce an electromagnetic force to oppose the motion of the shuttle element. This embodiment advantageously provides for the recovery of power by connecting the coil to a battery to charge the battery and thereby reducing overall power consumption of the fail-safe shut off valve.

Other preferred features of the present invention are set out in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 is a side view of a fail-safe shut off valve in accordance with the present invention.

Figure 2A is a cropped side view of the fail-safe shut off valve of Figure 1 , illustrating the configuration of valve components that permits fluid flow through the valve.

Figure 2B is the cropped side view of the fail-safe shut off valve of Figure 2A, illustrating the configuration of valve components that prevents fluid flow through the valve.

Figure 2C is a side view of a first opening configuration of a shuttle element within the fail-safe shut off valve of the present invention.

Figure 2D is a side view of a second opening configuration of a shuttle element within the fail-safe shut off valve of the present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Embodiments of the invention are now provided, with reference to the accompanying figures.

Figure 1 illustrates a failsafe shut-off valve 1 for a cylinder containing compressible fluid. Shown within Figure 1 are a pressure regulator 5 and a flow control stage 7, where a flow 2 of compressible fluid through the valve is via the regulator 5 and flow control stage 7. It is understood that these components are provided for the purposes of illustrating the present invention; as such the pressure regulator 5 and flow control stage 7 are optional components of the valve 1 . The operation of the fail-safe valve of the present invention will be described by reference to the components within the bounded area 3 of Figure 1 . The valve 1 comprises a shuttle element 9 moveable between an opening position and a closure position. Figure 1 illustrates the shuttle element 9 being in the opening position. For example, the shuttle element 9 may be provided within a shuttle channel 15 and configured to translate within that shuttle channel 15. Sealing elements 17 may be provided to ensure that the shuttle element 15 can translate within the shuttle channel 15 without resulting in any leakage of compressible fluid as a result of the movement of the shuttle element 9. The opening position and closure position will be described in detail below. The shuttle element 9 is biased toward the closure position. This biasing may be achieved by implementing any suitable biasing means, such as the spring 12 illustrated in Figure 1 . The failsafe shut-off valve 1 is configured such that when the shuttle element 9 is in the closure position, the shuttle element 9 causes actuation of a restriction element 1 1 of the valve 1 to restrict flow of the

compressible fluid through the valve 1 . Figure 1 illustrates the restriction element 1 1 as a poppet that can be actuated between an open position (as shown in Figure 1 ) and a closed position, where the poppet abuts a surface 18 of a flow channel of the valve, thereby blocking flow 2 of compressible fluid into a first portion 21 of the valve flow channel from a second portion 20 of the valve flow channel.

The valve 1 further comprises a driving means 13 configured such that, when activated, the driving means 13 provides a driving force to urge the shuttle element 9 toward the opening position. Thus, when the driving force is inactive, due to the biasing means the shuttle element 9 will move toward the closure position thereby actuating the restriction element 1 1 to close the valve 1 . The valve 1 therefore operates as a failsafe valve upon occurrence of conditions that would require a valve shut off. Advantageously, the driving means 13 comprises an electromechanical actuator configured to be activated by the supply of electrical current. In this example, an interruption of power to the driving means 13 will result in a shut off of the valve 1 . An example of an electromechanical actuator is a solenoid, where providing current to the solenoid will charge the solenoid to provide an electromechanical force.

Advantageously, and as shown in Figure 1 , the failsafe shut-off valve 1 further comprises a controller 14 configured to provide a control signal 16 to the driving means to activate the driving means 13. Through using the controller 14, the activation and deactivation of the driving means 13 can be more flexibly controlled. This provides advantages, for example, over the more straightforward operation of a fail-safe valve where the driving means 13 is activated by a supply of power and only deactivated upon interruption to that power. In contrast, the system of the present invention can be configured such that other activation and deactivation can occur upon other criteria. For example, and further

advantageously, the controller 14 is coupled to a sensor 19 and/or a data storage means 22. These elements allow the controller 14 to be configured to receive input data from the sensor and/or the data storage means to regulate activation and deactivation of the driving means - for example, the sensor could measure a temperature, compare the temperature to a threshold value, and deactivate the driving means 13 to close the valve 1 upon detection of a hazardous condition.

Generally, valve flow channels need to be sufficiently large to provide a practical flow of fluid for a variety of industrial purposes. Thus, the restriction means 1 1 is therefore required to be of equivalent size so as to be able to block passage of fluid through the flow channel when required. The larger the size of the restriction element, the greater the force that will be provided to it from the pressure of the compressible fluid flowing through the valve (due to increased surface area). Thus, to close the restriction element and shut off the valve, a correspondingly large force must be applied. Typical fail-safe valves known in the art provide a large biasing force directly to the restriction element (for example, by means of a spring) to bias the restriction element to the closed position. These valves operate by providing a correspondingly large driving force to oppose the biasing force to hold the restriction element in an open position, where upon removal of the driving force, the restriction element will return to the closed position. Generally speaking, the size of the force necessary for such a valve to operate with industrial cylinders will require a large power consumption.

The valve 1 of Figure 1 is provided to operate with much lower power consumption than the above described valves typical in the art. This is achieved due to the apparatus providing the restriction element 1 1 and the shuttle element 9 as separate elements, where the failsafe operation results from driving means 13 driving the shuttle element 9 instead of the restriction element 1 1 , where the shuttle element 9 causes actuation of the restriction element 1 1 when in the closure position. As described below in connection with Figures 2A and 2B, the shuttle element 9 is configured such that when in the closure position, the shuttle element blocks a flow pathway, thereby affecting relative pressures within the valve, resulting in actuation of the restriction element 1 1 .

The force required to hold shuttle element 9 in an opening position is much less than the force required to hold the restriction element 1 1 in an open position, thereby requiring less power to be consumed to operate the fail-safe shut off valve 2. Thus, the fail-safe shut off valve 2 can be provided with a battery (not shown in Figure 1 ), where the battery provides sufficient power for operation of the fail-safe shut-off valve 2.

Figures 2A - 2D illustrate an exemplary manner in which movement of the shuttle element 9 can cause an actuation of the restriction element 1 1 . As illustrated in Figure 2A, the failsafe shut-off valve 1 comprises a valve stem. The valve stem comprises a chamber 30 with chamber pathway 32 for fluid

communication of the chamber 30 with a first portion 21 of a flow channel of the valve. By providing fluid communication between the chamber 30 and the first portion 21 of the flow channel the chamber pressure equals that of the first portion 21 of the flow channel. Figure 2A is illustrated in a side-view, but it is to be understood that the illustrated first portion 21 can extends around the chamber wall 31 to connect to the chamber pathway 32 to provide fluid communication as described.

The valve stem further comprises the restriction element 1 1 . As illustrated in Figure 2A, the restriction element 1 1 comprises a flow-through channel 34 for passage of fluid from the second portion 20 of the valve flow channel into the chamber 30. Thus, when the shuttle element 9 is in the opening position, the compressible fluid can flow from the second portion 20 into the chamber 30 and through to the first portion 21 , via the chamber pathway 32.

The shut-off valve 1 is configured such that when the shuttle element 9 is in the closure position the chamber pathway 32 is blocked. This configuration is illustrated in Figure 2B. Movement of the shuttle element 9 to block the chamber pathway 32 isolates the chamber 30 from the first portion 21 of the flow channel. As such, the compressible fluid flows from the second portion 20 into the chamber 30 such that the chamber 30 is provided at the pressure of the second portion 20 of the flow channel. This results in a closure force on the restriction element 1 1 to actuate the restriction element 1 1 to restrict flow of the

compressible fluid from the second portion 20 of the flow channel to the first portion 21 of the flow channel. Figure 2B shows the valve 1 in a configuration following this closure, where the restriction element 1 1 abuts a surface 18 of the valve flow channel and blocks flow through the flow channel.

The closure force results from the chamber 30 being provided at the same pressure as the second portion 20 of the flow channel. As illustrated in Figures 2A and 2B, the restriction element 1 1 comprises a first surface 1 1 a provided inside the chamber 30, thus providing the first surface 1 1 a at the pressure inside the chamber 30. The restriction element 1 1 further comprises a second surface 1 1 b opposite the first surface 1 1 a, the second surface being provided outside the chamber 30 in the second portion 20 of the flow channel. The second surface 1 1 b is thus provided at the pressure of the second portion 20 of the flow channel. The valve 1 is configured, by means of the regulator 5 and flow control stage 7, or otherwise, to regulate a flow of compressible fluid such that a pressure of the fluid in the first portion 21 of the flow channel is less than the pressure in the second portion 20 of the flow channel. Thus in the arrangement of Figure 2A, with the chamber pathway 32 open, the pressure in the chamber will be lower than the pressure in the second portion 20 of the flow channel. This difference in pressure thus means the first surface 1 1 a will be at a lower pressure than the second surface 1 1 b, resulting in the restriction element experiencing an upward force toward an opening position. Thus, when the shuttle element 9 is in an opening position to permit fluid communication between the chamber 30 and the first portion 20 of the flow channel, the restriction element 1 1 remains in a configuration to permit flow of fluid through the flow channel and as such the valve is in an open state.

As described above, when the shuttle element 9 is in a closure

configuration, a flow of compressible fluid is provided through the flow channel 34 to bring the chamber 30 to the pressure of the second portion of the flow channel. Thus, when the shuttle element 9 is in the closure configuration, the first surface

1 1 a and the second surface 1 1 b are provided at the same pressure. As illustrated in Figures 2A and 2B, the second surface 1 1 b is smaller in surface area than the first surface 1 1 a. Consequently, when the shuttle element 9 is in the closure position and the first surface 1 1 a and the second surface 1 1 b are both provided at the pressure of the second portion 20 of the flow channel, different pressure forces are provided at the first surface 1 1 a and second surface 1 1 b. This difference in force results in actuation of the restriction element 1 1 in a downward direction to a configuration where the restriction element 1 1 blocks the flow channel of the valve 1 , thus closing the valve 1 .

Advantageously, and as illustrated in Figure 2A and Figure 2B, the valve stem further comprises a stem biasing means 36 configured to provide a force to the restriction element 1 1 to oppose the closure force. This stem biasing means may be any suitable biasing means, such as the spring illustrated in Figures 2A and 2B. Thus, when the shuttle element 9 is in the opening position, the pressure at the first surface 1 1 a is low enough for the stem biasing means 36 to pull the restriction element 1 1 upwards into a configuration to allow fluid flow. Providing the stem biasing means 36 can serve as a way to configure the forces, and therefore pressure differences, necessary to ensure opening and closing of the valve 1 as a result of the movement of the shuttle element 9.

In the illustrated embodiments, the forces required to move the restriction element 1 1 comes from the compressible fluid and not from the driving means 13, thereby removing the need for large power loads on the driving means 13. Furthermore, and advantageously, the shuttle element 9 can be provided with a smaller diameter than the diameter of the restriction element 1 1 . This means that smaller area will be exposed a compressible pressure making the shuttle element 9 easier to move in and out of the chamber pathway 32, further reducing the driving force required to be provided by the driving means.

As described above, providing a separate shuttle element 9 in itself results in a reduction in the required power to operate the fail-safe shut off valve 1 .

However, and as will be described below, the manner in which the shuttle element 9 is driven by the driving means 13 can provide further reductions in the required power to operate the fail-safe shut off valve 1 . In particular, the driving means 13 can be temporarily switched off, to save power over a period of operation, without the switch-off resulting in an unwarranted closure of the valve 1 . Thus, power can be saved without affecting the operation of the fail-safe shut off valve 1 .

As mentioned above, the shuttle element 9 is biased toward a closure position. Advantageously, the shuttle bias provided to the shuttle element 9 is such that in the absence of the driving force, a movement of the shuttle element 9 is damped. This damping may be provided in any suitable manner - for example, the valve 1 may comprise a shuttle biasing means such that the bias provided to the shuttle element comprises at least one of a mechanical bias (e.g. an electromechanical element to provide electromechanical damping) and a viscous bias (such as resistance to a viscous fluid to provide viscous damping).

By providing a damping to the shuttle element 9, the shuttle element 9 takes longer to move from an opening configuration to a closure configuration than it would without the damping means. Thus, in the event of a loss of power, the valve will not shut immediately, but would take a predetermined time for the valve to close (for example, 5 seconds). This is the time it takes for the shuttle element 9 to move to the closure position; when the shuttle element 9 reaches the closure position, the actuation of the restriction element is prompt, resulting in a very quick closure of the valve. For example, the spring 12 is coupled to the shuttle element 9 and driving means 13 such that when the driving means is activated the movement of the shuttle compresses the spring 12, and upon deactivation of the driving means the spring 12 will expand to its original configuration, moving the shuttle element 9 to the closure configuration. The spring is manufactured such that the expansion is damped, and it will take a restoration time for the spring to return to its original configuration. Since the shuttle element 9 is coupled to the spring 12, the shuttle element will therefore move from the opening configuration to the closure configuration in said restoration time. This may be achieved, for example, by providing an

overdamped biasing means, with a damping ratio greater than 1 . The restoration time may be predetermined by suitable selection of a damping means and damping parameters.

As detailed above, the driving means 13 may be coupled to a controller 14 that is configured to activate and deactivate the driving means 13 by providing a control signal 16 to the driving means 13. Further advantageously, the control signal 16 is provided to activate and deactivate the driving means 13 at a driving frequency. This means that the driving means will be activated and deactivated periodically. Thus, over the operational time of the fail-safe shut off valve, the driving force is provided to the shuttle element 9 for only a fraction of that operational time. Since the shuttle element 9 is damped, and will take time to move from an opening position to a closure position, the shuttle element 9 will not immediately move into the closure position of the shuttle element 9 to close the valve 1 . If the driving means 13 is turned back on again before the shuttle element 9 reaches the closure position, then the valve 1 will continue to permit a flow of compressible fluid despite the interruption to the power supplied to the driving means 13. Thus, power does not need to be constantly provided to the driving means 13 to ensure continued flow of compressible fluid through the valve 1 . Rather, the power can be periodically switched on and off, thereby reducing the total amount of power provided to the valve 1 over the operational time of the fail-safe shut off valve 1 . In this advantageous embodiment, the driving frequency is greater than the reciprocal of the time required for the shuttle element 9 to move from the open position to the closed position under the action of the bias. Thus, the shuttle element 9 will oscillate between two positions, and will only move toward the closure position upon prolonged interruption to the power supplied to the driving means.

However, as will be appreciated from Figures 2A and 2B, there may be positions of the shuttle element 9 between the opening position of Figure 2A and the closure position of Figure 2B that may partially restrict flow through the chamber pathway 32 (e.g. the shuttle element 9 being in a position proximate to the closure position of Figure 2B). These intermediate positions may still result in some actuation of the restriction element 1 1 , thus reducing flow through the valve 1 . Thus, in a further advantageous embodiment, the opening position of the shuttle element 9 is one of a plurality of opening positions of the shuttle element 9. When the shuttle element is in each of the plurality of opening positions, the restriction element 1 1 is provided to allow unrestricted flow of compressible fluid through the valve 1 . Exemplary opening positions are illustrated in Figures 2C and 2D. As can be seen in these figures, in neither opening position is the chamber pathway 32 restricted by any amount, thus ensuring sufficient fluid communication between the chamber 30 and the first portion 21 . Figures 2C and 2D are exemplary only, and it is understood that an opening position of the shuttle element 9 is when sufficient fluid communication between the chamber 30 and the first portion 21 of the flow channel is present to ensure the pressure in the chamber 30 is low enough for the restriction element 1 1 to remain in a position to permit unrestricted flow through the valve 1 . For example, a small obstruction to the fluid chamber pathway 32 may not result in a movement of the restriction element 1 1 . In this advantageous embodiment, the driving frequency is greater than the time required for the shuttle element 9 to move from a first opening position to a second opening position, such as the opening positions illustrated in Figures 2C and 2D. Thus, the driving means 13 is switched on and off to save power without interrupting or reducing the flow of compressible fluid through the valve 1 .

As described above, and illustrated in Figure 1 , the controller 14 may be coupled to a data storage means 22. The driving frequency implemented by the driving means may be retrieved from the data storage means 22, or calculated using information stored on the data storage means 22. Advantageously, the controller 14 is configured to base the driving frequency on data collected from the sensor 9. For example, the sensor 9 could comprise a flow-rate sensor arranged downstream from the restriction element 1 1 (e.g. measuring the flow through first portion 21 ), and/or a flow-rate sensor arranged upstream from the restriction element 1 1 (e.g. measuring the flow through second portion 20). The controller 14 can then detect the flow rate through the valve and adjust the driving frequency accordingly - for example, if the flow rate is too low, then this may be indicative of the shuttle element partially blocking the chamber pathway 32; the driving frequency could then be increased by the controller to ensure the shuttle element 9 remains in an opening position as described above with respect to Figures 2C and 2D.

In one advantageous embodiment, not illustrated in the figures, a damping means can be provided as an electrical damping that can also serve as energy recovery. In this embodiment, the damping is provided by an electrical damping means. The electrical damping means comprises a magnet attached to the shuttle element and a coil provided around the shuttle element 9. For example, the coil may be arranged around a chamber in which the shuttle element 9 moves. A movement of the shuttle element 9 induces a current in the coil to produce an electromagnetic force to oppose the motion of the shuttle element 9. This can serve both to damp the motion of the shuttle element 9, but also partially recover some power from the movement of the shuttle. This is particularly advantageous in the embodiment where the controller 14 is configured to provide the control signal at the driving frequency, causing the shuttle element 9 to oscillate back and forth within the shuttle chamber. The magnet and coil arrangement can be provided in combination with a separate biasing means (e.g. a spring 12) to bias the shuttle element toward the closure position, as described above.

The fail-safe shut off valve 1 described herein is suitable for adaption to any number of valves or valve assemblies, including integrated shut off valves, or regulator valves.

Although preferred embodiments of the invention have been described, it is to be understood that these are by way of example only and that various modifications may be contemplated.

Claims

1 . A failsafe shut-off valve for a cylinder containing compressible fluid, the valve comprising:

a shuttle element moveable between an opening position and a closure position and being biased toward the closure position, wherein when the shuttle element is in the closure position, the shuttle element causes actuation of a restriction element of the valve to restrict flow of the compressible fluid through the valve; and

a driving means configured such that when activated the driving means provides a driving force to urge the shuttle element toward the opening position.

2. The failsafe shut-off valve of claim 1 , further comprising a controller configured to provide a control signal to the driving means to activate the driving means.

3. The failsafe shut-off valve of claim 1 or claim 2, wherein the bias provided to the shuttle element is such that in the absence of the driving force, a movement of the shuttle element is damped.

4. The failsafe shut-off valve of claim 3 when dependent on claim 2, wherein the control signal is provided to activate and deactivate the driving means at a driving frequency, the driving frequency greater than the reciprocal of the time required for the shuttle element to move from the open position to the closed position under the action of the bias.

5. The failsafe shut-off valve of claim 4, wherein the opening position of the shuttle element is one of a plurality of opening positions of the shuttle element, wherein in each of the plurality of opening positions, the restriction element is provided to allow unrestricted flow of compressible fluid through the valve, and the driving frequency is greater than the time required for the shuttle element to move from a first opening position to a second opening position.

6. The failsafe shut-off valve of any preceding claim, wherein the valve comprises a valve stem, the valve stem comprising:

a chamber with chamber pathway for fluid communication of the chamber with a first portion of a flow channel of the valve,

5 the restriction element, the restriction element comprising a flow-through channel for passage of fluid from a second portion of the valve flow channel into the chamber, wherein the shut-off valve is configured such that when the shuttle element is in the closure position the chamber pathway is blocked, thereby isolating the chamber from the first portion of the flow channel such that the o chamber is provided at the pressure of the second portion of the flow channel and resulting in a closure force on the restriction element to actuate the restriction element to restrict flow of the compressible fluid from the second portion of the flow channel to the first portion of the flow channel. 5

7. The failsafe shut-off valve of claim 6, wherein the restriction element

comprises:

a first surface provided inside the chamber and at the pressure inside the chamber;

a second surface opposite the first surface, provided outside the chamber 0 in the second portion of the flow channel and at the pressure of the second

portion of the flow channel;

wherein the second surface is smaller in surface area than the first surface, such that when the shuttle element is in the closure position and the first and second surface areas are provided at the pressure of the second portion of 5 the flow channel, different pressure forces are provided at the first and second areas resulting in actuation of the restriction element.

8. The shut-off valve of claim 7, wherein the valve stem further comprises a stem biasing means configured to provide a force to the restriction element to 0 oppose the closure force.

9. The failsafe shut-off valve of any preceding claim, wherein the driving means comprises an electromechanical actuator configured to be activated by the supply of electrical current.

10. The failsafe shut-off valve of any preceding claim, further comprising a shuttle biasing means such that the bias provided to the shuttle element comprises at least one of a mechanical bias and a viscous bias.

1 1 . The failsafe shut-off valve of any of claims 4 - 10, when dependent on claim 3, wherein the damping is provided by an electrical damping means, the electrical damping means comprising a magnet attached to the shuttle element and a coil provided around the shuttle element, such that a movement of the shuttle element induces a current in the coil to produce an electromagnetic force to oppose the motion of the shuttle element.

12. An electronic shut-off valve substantially as herein described with reference to Figures 1 and 2A - 2D of the accompanying drawings.