Safety valve for pressure vessel

Abstract

Safety valve (1) for a pressure device comprising: - a valve housing (3) arranged to connect the safety valve (1) to the pressure device, - a transfer channel (8) arranged to be in fluidic communication with the pressure device, - a drain channel (7), - a sealing element (6) arranged to seal the transfer channel (8) when it is in a sealed state and arranged to allow free passage between the transfer channel (8) and the drain channel (7) when it is in a drained state, - an electro-pyrotechnic device (2), - a thermal release element (4) arranged to maintain the sealing element (6) in the sealed state below a predetermined activation temperature and to allow free passage of the sealing element (6) above the activation temperature,characterized in that the thermal release element (4) is arranged between the sealing element (6) and the electro-pyrotechnic device (2) such that the electro-pyrotechnic device (2) participates in maintaining the sealing element (6) in the sealed state. Figure for the abstract: Fig. 1,

Description

Title of the invention: Safety valve for pressure device Technical field of the invention

[0001] The present invention generally relates to a safety device for pressurized devices such as tanks or distribution networks. Such devices may be static or mobile and store or diffuse gases or liquids. They may be mounted on vehicles, for example, to store and / or diffuse hydrogen. State of the art

[0002] Safety valves are known in the prior art which are mostly passive. Document DE8702136 discloses such a device which also has the possibility of being activated on command. However, this system is bulky and requires many parts. The invention therefore aims to reduce the size of the device to make it easier to integrate and to reduce its number of components. Statement of the invention

[0003] An aim of the present invention is to overcome the drawbacks of the prior art mentioned above and in particular, first of all, to propose a more compact safety valve.

[0004] For this purpose, a first aspect of the invention relates to a safety valve for a pressure device comprising: - a valve housing arranged to connect the safety valve to the pressure device, - a transfer channel arranged to be in fluid communication with the pressure device, - a drainage channel, - a sealing element arranged to seal the transfer channel when it is in a sealed state and arranged to leave a free passage between the transfer channel and the drain channel when it is in a drain state, - an electro-pyrotechnic device, - a thermal release element arranged to maintain the sealing element in the sealed state below a predetermined activation temperature and to leave the sealing element free above the activation temperature, characterized in that the thermal release element is arranged between the sealing element and the electropyrotechnic device such that the electropyrotechnic device participates in maintaining the sealing element in the sealed state. In other words, the safety valve is arranged so that the pressure in the pressure device is able, when the thermal release element has released (or no longer holds) the closure element, to release the passage between the transfer channel and the drain channel, the passage initially closed or sealed by the closure element. For example, the safety valve is suitable for protecting a hydrogen storage tank under a nominal pressure of the order of 700 bar. However, it may not be defined to secure the entire pressure range, depending on the construction of the tank; the valve may be defined only to drain the tank when the pressure is above a predetermined value, for example 150, 180 or 200 bar.Typically, according to this implementation, the electro-pyrotechnic device participates in the wedging (or maintenance) of the thermal release element and thus integrates at least two functions with respect to thermal release, namely wedging in its rest position and breaking in its activated position. Thus, fewer parts and less clearance are necessary for the integration of these two functions, which makes the safety valve more compact.

[0005] The invention can then be defined with the following characteristics, taken individually or in combination.

[0006] According to one embodiment, the closure element may be a slider or a frangible element. In other words, the closure element may be a movable element such as a slider, a needle, a valve or a frangible element arranged to deform, break or split. In other words, the closure element, when it is no longer supported, may be moved or deform plastically so as to free the passage between the transfer channel and the drain channel.

[0007] According to one embodiment, the thermal release element may be a thermal bulb arranged to rupture beyond the predetermined activation temperature. In other words, the thermal release element is a thermal trigger element commonly called a thermo bulb in English. Such an element may be formed from an enclosure or a bulb containing a liquid, the element being arranged to rupture under the effect of the expansion of said liquid or an increase in pressure inside the enclosure beyond a predetermined temperature. When the thermal release element is ruptured, the support of the closure element is no longer ensured and the emptying of the pressurized device can take place.

[0008] According to one embodiment, the valve housing may comprise at least one exchange orifice separate from the drain channel and the transfer channel and arranged to put the thermal release element in fluid communication with the external environment of the safety valve. The exchange orifice makes it possible to ensure that a temperature surrounding the safety valve will be quickly applied or perceived by the thermal release element.

[0009] According to one embodiment, the electro-pyrotechnic device may comprise or may be an electro-pyrotechnic igniter arranged in direct contact with the thermal release element. According to this embodiment the number of parts is further reduced and the responsiveness of the valve is improved.

[0010] According to one embodiment, the safety valve may comprise: - a piston arranged to move between a rest position and an activated position, - the electro-pyrotechnic device is an electro-pyrotechnic igniter arranged to move the piston from the rest position to the activated position upon an electrical firing pulse. In the embodiment, the piston is a movable transfer element arranged between the electro-pyrotechnic igniter and the thermal release element so as to transfer a force and / or pressure generated by the electro-pyrotechnic igniter to the thermal release element.

[0011] According to one embodiment, the piston may be in direct contact with the thermal release element. According to this embodiment, the responsiveness of the valve is improved.

[0012] According to one embodiment, the electro-pyrotechnic device, the thermal release element and the closure element can be arranged coaxially along an electrical connection pin axis of the electro-pyrotechnic device. According to this embodiment, the size of the valve is reduced.

[0013] According to one embodiment, the thermal release element and the sealing element may be arranged coaxially along a drain axis distinct from an electrical connection pin axis of the electro-pyrotechnic device.

[0014] According to one embodiment, the electro-pyrotechnic device may comprise an actuation housing arranged to interface with the valve housing. According to this embodiment, the manufacture of the valve is more flexible. Indeed, the same valve housing may be used for an active valve according to the invention or a solely passive valve.

[0015] According to one embodiment, the actuator housing may interface with the valve housing via a screwed interface or an interference fit.

[0016] According to one embodiment, the actuation housing and the electropyrotechnic device can form an actuation subassembly. According to this embodiment, the manufacture of the valve is more flexible.

[0017] According to one embodiment, the safety valve may comprise a deformable wedging element arranged to participate in maintaining the thermal release element. According to this embodiment, the maintenance or wedging of the thermal release element is optimized and assembly is facilitated. Indeed, the deformable wedging element makes it possible to take up the assembly clearances of the safety valve and / or the manufacturing tolerances of the various components and / or the displacement or deformation of components during the life of the safety valve. The deformable wedging element may take the form of an O-ring or flat seal, a conical washer or any other shape compatible with the function. The deformable wedging element may be made of metal and / or natural or synthetic rubber and / or EPDM. The wedging element may be integral with the piston, assembled on the piston or be the piston. The wedging element may be a spring. Description of figures

[0018] Other characteristics and advantages of the present invention will appear more clearly on reading the following detailed description of an embodiment of the invention given by way of non-limiting example and illustrated by the appended drawings, in which:

[0019] [Fig-1] represents a sectional view of a safety valve according to a first embodiment of the invention, the section of [Fig.l] being made along a section plane comprising an axis of an electrical connection pin of the electropyrotechnic device;

[0020] [Fig.2] represents the safety valve of [Fig.l] with the piston in its position activated and the shutter element released;

[0021] [Fig.3] represents a sectional view of a safety valve according to a second embodiment of the invention, the section of [Fig.2] being made along a sectional plane comprising an axis of the electrical connection pin of the electropyrotechnic device;

[0022] Detailed description of embodiment(s)

[0023] [Fig.l] represents a safety valve 1 for a pressure device comprising: - a valve box 3 arranged to connect the safety valve 1 to the pressure device, - a transfer channel 8 arranged to be in fluid communication with the pressure device, - a drain channel 7, - a closing slide 6 arranged to close the transfer channel 8 when it is in a closed state as shown in [Fig.l] and arranged to leave a free passage between the transfer channel 8 and the drain channel 7 when it is in a drain state as shown in [Fig.2], - an electro-pyrotechnic device 2 formed of an electro-pyrotechnic igniter 21 and a piston 23 arranged to move between a rest position and an activated position upon firing of the electro-pyrotechnic igniter 21, - a thermal release element 4 formed of a frangible bulb 42 enclosing a liquid 41 arranged to maintain the shutter slide 6 in the shutter state below a predetermined activation temperature and to leave the shutter slide 6 free above the activation temperature.

[0024] The closure slide 6 is arranged to be movable in translation along the axis of the transfer channel 8. The seal between the closure slide 6 and the transfer channel 8 is ensured by a sealing O-ring 61. The closure slide 6 is further wedged along its translation axis by a flexible wedging element 62 which can take the form of an O-ring with a suitable hardness.

[0025] The thermal release element 4 is arranged between the shutter slide 6 and the piston 23 of the electropyrotechnic device 2 so that the electropyrotechnic device 2 participates in maintaining or wedging the shutter slide 6 in the shuttered state. Thus, when pressure is applied to the shutter slide 6, typically by the pressure present in the pressure device, the shutter slide 6 cannot move since it is maintained by means of the thermal release element 4 and the electropyrotechnic device 2, in particular the piston 23.

[0026] In the embodiment shown, the electro-pyrotechnic device 2 comprises, in addition to the electro-pyrotechnic igniter 21 and the piston 23, an actuation box 22 arranged to interface with the valve box 3. This embodiment makes it possible to attach the electro-pyrotechnic device 2 to a standard safety valve 1, not provided with an active mode according to the invention. Alternatively, the valve box 3 can be specific to directly receive the pyrotechnic device 2 without an actuation box 22 to further reduce the number of parts. When the safety valve 1 comprises an actuation box 22, the following two assembly options can be envisaged: - the actuator housing 22 is assembled to the valve housing 3 before the assembly of the piston 23 and the electro-pyrotechnic igniter 21, or - the piston 23 and the electro-pyrotechnic igniter 21 are assembled to the actuation housing 22 to form an actuation subassembly which can then be assembled on the valve housing 3.

[0027] The safety valve 1 is arranged to operate in an active or passive mode.

[0028] In the passive mode, when a predetermined temperature is reached, the frangible bulb 42, for example formed of glass, breaks under the pressure or expansion of the liquid 4L. The temperature outside the safety valve 1 is transmitted to the liquid 41 via the exchange orifice 5. Once broken, the frangible bulb 42 no longer supports the closure slide 6 which can translate (towards the top of [Fig.l]) under the effect of the pressure present in the transfer channel 8 and thus free the passage between the transfer channel 8 and the drain channel 7.

[0029] In the active mode, when an electrical firing signal is applied to the electro-pyrotechnic device 2 and in particular to the electro-pyrotechnic igniter 21, via at least one connection pin 210, pressure or force is applied to the piston 23 (directly or indirectly), causing the piston 23 to move towards the frangible bulb 42 (i.e. towards the bottom of [Fig.l]) which has the effect of breaking the frangible bulb 42. Once the frangible bulb 42 is broken, as in the passive mode, the closure slide 6 is no longer supported, it can translate (towards the top of [Fig.l]) under the effect of the pressure present in the transfer channel 8 and thus free the passage between the transfer channel 8 and the drain channel 7. The state of the safety valve 1 after operation according to the active mode is shown in [Fig.2]. The electro-pyrotechnic igniter 21 of this embodiment may be sealed (i.e., it does not release gas) or may generate and release gases. In the first case, the electro-pyrotechnic igniter 21 is arranged to deform, in particular to expand or swell, depending on the direction of movement of the piston 3, and it is therefore the electro-pyrotechnic igniter 21 which directly moves the piston 23. In the second case, it is the gases produced and released by the electro-pyrotechnic igniter 21 which move the piston 23.

[0030] It is understood that according to the present invention, an electro-pyrotechnic igniter 21 is a device comprising at least one connection pin 210, at least one pyrotechnic material, at least one envelope containing said at least one pyrotechnic material and at least one firing element (typically a resistive bridge) connected to said at least one connection pin 210 and arranged to fire the pyrotechnic material. A protective cap may be added to these elements, in particular when the envelope is formed from a metallic material.

[0031] The embodiment shown in [Fig. 3] is similar to that shown in [Fig. 1] except that it does not include a piston. The elements common to both embodiments will not be detailed again.

[0032] In the embodiment of [Fig. 3], the electro-pyrotechnic igniter 21 directly participates in maintaining the thermal release element 4. As in the previous embodiment, the electro-pyrotechnic igniter 21 may or may not be sealed. This embodiment makes it possible to further reduce the overall size of the safety valve 1 as well as its number of parts. In this embodiment, it may be advantageous for the electro-pyrotechnic igniter 21 to include a protective cap whose shape matches part of the shape of the thermal release element 4 to maintain or wedge it optimally. Industrial application

[0033] A safety valve according to the present invention, and its manufacture, are capable of industrial application.

[0034] It will be understood that various modifications and / or improvements obvious to those skilled in the art can be made to the different embodiments of the invention described in the present description without departing from the scope of the invention. In particular, the closure slide can be replaced by a cover arranged to break under the pressure present in the transfer channel when it is not supported by the thermal release element. Furthermore, other types of thermal release element can be envisaged.

Claims

Claims

1. Safety valve (1) for a pressure device comprising: - a valve housing (3) arranged to connect the safety valve (1) to the pressure device, - a transfer channel (8) arranged to be in fluid communication with the pressure device, - a drain channel (7), - a closure element (6) arranged to close the transfer channel (8) when it is in a closed state and arranged to leave a free passage between the transfer channel (8) and the drain channel (7) when it is in a drain state, - an electro-pyrotechnic device (2), - a thermal release element (4) arranged to maintain the closure element (6) in the closed state below a predetermined activation temperature and leave the closure element (6) free above the activation temperature,characterized in that the thermal release element (4) is arranged between the closure element (6) and the electro-pyrotechnic device (2) so that the electro-pyrotechnic device (2) participates in maintaining the closure element (6) in the closure state.,

2. Safety valve (1) according to claim 1 in which the closure element (6) is a slide or a frangible element.

3. Safety valve (1) according to one of the preceding claims in which the thermal release element (4) is a thermal bulb arranged to rupture beyond the predetermined activation temperature.

4. Safety valve (1) according to one of the preceding claims in which the valve housing (3) comprises at least one exchange orifice (5) separate from the drain channel (7) and from the transfer channel (8) and arranged to put the thermal release element (4) into fluid communication with the external environment of the safety valve (1).

5. Safety valve (1) according to one of the preceding claims wherein the electro-pyrotechnic device (2) comprises or is an electro-pyrotechnic igniter (21) arranged in direct contact with the thermal release element.

6. Safety valve (1) according to one of claims 1 to 4 comprising: - a piston (23) arranged to move between a rest position and an activated position, - the electro-pyrotechnic device (2) is an electropyrotechnic igniter (21) arranged to move the piston (23) from the rest position to the activated position on an electrical firing pulse.

7. Safety valve (1) according to the preceding claim in which the piston (23) is in direct contact with the thermal release element (4).

8. Safety valve (1) according to one of the preceding claims wherein the electropyrotechnic device (21), the thermal release element (4) and the closure element (6) are arranged coaxially along an electrical connection pin axis (210) of the electropyrotechnic device (2).

9. Safety valve (1) according to one of claims 1 to 8 in which the thermal release element (4) and the closure element (6) are arranged coaxially along a drain axis distinct from an electrical connection pin axis (210) of the electro-pyrotechnic device (2).

10. Safety valve (1) according to one of the preceding claims in which the electro-pyrotechnic device (2) comprises an actuating housing (22) arranged to interface with the valve housing (3).

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