SAFETY DEVICE FOR A TANK INTENDED TO CONTAIN A PRESSURIZED GAS

Abstract

The safety device (3) comprises: a ventilation channel (9) intended to establish fluid communication between an internal volume (10) defined by a tank and the outside of the tank (2), a safety piston (5) movable between a closure position in which it closes the ventilation channel (9), and a safety position in which it does not close the ventilation channel, a first safety member (6) which is deformable and that keeps the safety piston in the closure position against an elastic force returning the safety piston to the safety position, means (7) for deforming the first safety member (6), which means are movable between a resting position and a deformation position, and at least a second safety member (8) intended, in a resting position, to hold the deformation means in the resting position against an elastic force returning the deformation means back to the deformation position when the second safety member experiences a temperature lower than a predetermined temperature and, in a working position, to release the elastic force for returning the deformation means in the deformation position when the second safety member experiences a temperature higher than the predetermined temperature,

The second safety member (8) is formed by a safety cable (16) made of a material that has low mechanical resistance to fire.

Claims

1. A safety device (3) for a tank (2) intended to contain a pressurized gas, comprising: a ventilation channel (9) intended to establish fluid communication between an internal volume (10) defined by the tank (2) and the outside of the tank (2), a safety piston (5) movable between a closure position in which it closes the ventilation channel (9), and a safety position in which it does not close the ventilation channel (9), a first safety member (6) which is deformable and configured to hold the safety piston (5) in the closure position against an elastic return force returning the safety piston (5) in the safety position, the safety device further comprising: deformation means (7) for deforming the first safety member (6), wherein the deformation means (7) are movable between a resting position and a deformation of the first safety member (6) position, and at least a second safety member (8) intended, in a resting position, to hold the deformation means (7) in the resting position against an elastic force returning the deformation means (7) in the deformation of the first safety member (6) position when the second safety member (8) is subjected to a temperature below a predetermined temperature and, in a working position, to release the elastic force returning the deformation means (7) in the deformation of the first safety member (6) position when the second safety member (8) is subjected to a temperature higher than the predetermined temperature, wherein the second safety member (8) is formed by a safety cable (16) made of a material having low mechanical resistance to fire.

2. The safety device (3) according to claim 1, wherein the first safety member (6) is formed by a glass bulb containing a fluid, the fluid being intended to exert pressure on the bulb when subjected to a temperature above the predetermined temperature so as to break the bulb.

3. The safety device (3) according to any one of the preceding claims, wherein the elastic force returning the deformation means (7) in the deformation of the first safety member (6) position is provided by a spring (14) resting on a support seat having an opening configured to allow the passage of the second safety member.

4. The device (3) according to any one of the preceding claims, wherein the safety piston (5) has a housing (11) configured to house at least part of the deformation means (7) when the safety piston (5) is in the safety position and the deformation means (7) are in the deformation of the first safety member (6) position.

5. The safety device (3) according to any one of the preceding claims, wherein the deformation means (7) comprise a striking element.

6. The safety device (3) according to any one of the preceding claims, wherein the second safety member (8) comprises an elastic member.

7. The safety device (3) according to any one of the preceding claims, wherein the safety cable (16) is made of a material classified D according to the European standard EN 13501-1 or of a material classified M3 or M4 according to the French standard NF P92-507.

8. The safety device (3) according to any one of the preceding claims, wherein the safety cable (16) is made of a material selected from the group consisting of rubbers, polyamides, wools, polyesters, high-density polyethylenes, preferably of high molecular weight, polypropylenes, and combinations thereof.

9. The safety device (3) according to claim 8, wherein the safety cable (16) is made of polypropylene.

10. The safety device (3) according to any one of the preceding claims, wherein the safety cable (16) is made of a material having a mechanical resistance to fire of between 10 seconds and 1 hour, preferably between 1 minute and 45 minutes, even more preferentially between 10 minutes and 30 minutes.

11. The safety device (3) according to any one of the preceding claims, wherein the second safety member (8) is coupled to the deformation means (7) by a third safety member (19) intended to cooperate with the second safety member (8) so as to hold the second safety member (8) in the resting position when the second safety member (8) is subjected to a temperature below the predetermined temperature and to elastically return the second safety member (8) to the working position when the second safety member (8) is subjected to a temperature higher than the predetermined temperature.

12. A kit for manufacturing a safety device (3) according to claim 11, characterized in that it comprises a second safety member (8) according to claim 11 and a third safety member (19) according to claim 11, the second safety member (8) and the third safety member (19) being intended to be added to a housing (4) of the safety device (3) comprising the aeration channel (9), the safety piston (5) and the first safety member (6) of the safety device (3).

13. A tank (2) for containing a pressurized gas, characterized in that it is equipped with a safety device (3) according to any one of claims 1 to 11.

14. A method of manufacturing a safety device (3) according to any one of claims 1 to 11, wherein the following steps are carried out: attaching the deformation means (7) to a housing (4) comprising the ventilation channel (9), the safety piston (5) and the first safety member (6), and attaching the second safety member (8) to the housing (4).

Description

BRIEF DESCRIPTION OF THE FIGURES

[0044] The invention will be better understood upon reading the following description, which is provided merely as a non-limiting example and with reference to the appended drawings, wherein:

[0045] FIG. 1 is a schematic view of a motor vehicle comprising a tank fitted with a safety device according to the invention;

[0046] FIG. 2 is a schematic cross-sectional view of a first embodiment of the safety device according to the invention shown in the resting position (A) and in the safety position (B); and

[0047] FIG. 3 is a schematic cross-sectional view of a second embodiment of the safety device according to the invention shown in the resting position (A) and in the safety position (B).

[0048] FIG. 4 is a schematic top view of the means for attaching the second safety member to the deformation means according to the second embodiment.

DETAILED DESCRIPTION

[0049] FIGS. 1 to 4 show two embodiments of a safety device according to the invention.

[0050] FIG. 1 schematically shows a motor vehicle 1 comprising a tank 2 intended to contain a pressurized gas equipped with a safety device 3 according to the invention.

[0051] In the present case, the tank 2 is intended to contain fuel for the motor vehicle 1, more specifically the tank 2 is intended to contain compressed dihydrogen, typically between 300 and 700 bar. A single safety device 3 is shown in FIG. 1. In accordance with other embodiments, the number of safety devices 3 fitted to the tank is greater, for example between two and twenty. In other embodiments, the safety device 3 can be fitted to tanks other than fuel tanks or dihydrogen tanks.

[0052] FIG. 2 shows a first embodiment of a safety device 3 according to the invention, wherein the safety device 3 is shown in its resting position (FIG. 2A) and in its safety position (FIG. 2B).

[0053] The safety device 3 comprises a body or housing 4 on which are mounted a safety piston 5, a first safety member 6, deformation means 7 and a second safety member 8.

[0054] The housing 4 comprises a ventilation channel 9 intended to fluidly connect an internal volume 10 defined by the tank 2 and the outside of the tank 2. A first end of the ventilation channel 9 opens into the internal volume 10 of the tank 2 and a second end of the ventilation channel 9 vents to the outside of the tank 2.

[0055] The safety piston 5 is slidably mounted inside the ventilation channel 9 that is movable between a closure position wherein it closes the ventilation channel 9 (FIG. 2A), and a safety position wherein it does not close the ventilation channel 9 (FIG. 2B). In other words, in the closure position, the safety piston 5 prevents fluid communication between the internal volume 10 and the outside of the tank 2. In the closure position, a seal 5a arranged between the safety piston 5 and an inner wall of the ventilation channel 9 cooperates with part of the safety piston 5 to prevent the gas present in the internal volume 10 from escaping through the ventilation channel 9. In the safety position, the safety piston 5 no longer closes, at least partially, the ventilation channel 9 so that the internal volume 10 of the tank 2 fluidly communicates with the outside of the tank. In the safety position, the seal 5a no longer cooperates with the safety piston 5 to seal the ventilation channel 9, as a result, the pressurized gas in the internal volume 10 escapes via the ventilation channel 9. The seal improves the sealing when the safety piston 5 closes the ventilation channel 9. In an alternative embodiment, the safety device 3 may not comprise a seal 5a. A sliding ring 5b mounted on the safety piston 5 guides the sliding of the safety piston 5 between the closure position and the safety position. The safety piston 5 is machined to provide a hollow housing 11.

[0056] The first safety member 6 is deformable. It is configured to keep the safety piston 5 in the closure position against an elastic force returning the safety piston 5 in the safety position. In the present case, the first safety member 6 is frangible and is formed by a glass bulb containing a fluid intended to exert pressure on the bulb so as to break it when it is subjected to a predetermined temperature. The first safety member 6 keeps the safety piston 5 in the closure position and is located between the safety piston 5 and a fixed point 12. The glass bulb is thus dimensioned to hold the safety piston 5 in the closure position until it is broken. In another embodiment, the first safety member 6 is fusible when subjected to the predetermined temperature. In this case, the predetermined temperature is between 95 C. and 150 C.

[0057] The elastic force returning the safety piston 5 back to the safety position is supported by a compression spring 13. In the closure position, the spring 13 is compressed by the safety piston 5 under the action of the first safety member 6 (FIG. 2A). In other embodiments, the elastic force returning the safety piston 5 in the safety position may be carried by a member other than a spring 13 in compression.

[0058] The deformation means 7 are intended to deform the first safety member 6. In the present case, this deformation consists in the destruction of the glass bulb. The deformation means 7 are movable between a resting position (FIG. 2A) and a position wherein the first safety member 6 is deformed (FIG. 2B), that is, in this case, a position wherein the glass bulb is destroyed (the destroyed bulb is not shown). The deformation means 7 comprise a needle-shaped striking element. The striking element is the part of the deformation means 7 that is intended to come into contact with the first safety member 6 in order to deform it, that is, to destroy it in this case. In other embodiments, the striking element is different and takes, for example, the form of a bayonet, arrow or a blade.

[0059] The housing 11 in the safety piston 5 is configured to houses at least part of the deformation means 7 when the safety piston 5 is in the safety position and the deformation means 7 are in the deformation position (FIG. 2B), so that the deformation means 7 do not interfere with the passage of the safety piston 5 into the safety position.

[0060] The striking element of the deformation means 7 rests on a compression spring 14 which elastically returns the striking element in the position for deforming the first safety member 6. The spring 14 and the striking element are housed in a recess in the housing 4 of the safety device 3. This recess opens onto an external opening in the housing 4 of the safety device 3. A washer 15 is attached to the outer opening of the recess and forms a support seat for the spring 14. The washer 15 has an annular shape having a central through-hole. At least part of the opening in the washer 15 is composed of and/or covered by lubrication means. The lubrication means may be solid, liquid or paste-like. The lubrication means are for example grease, lubricating oil or a solid non-stick coating such as Teflon.

[0061] The second safety member 8 consists of a two-meter-long safety cable 16 which corresponds approximately to the length of the tank 2. In other embodiments, the length of the safety cable 16 is different, for example between one and ten meters, preferably between one and three meters. Advantageously, the length of the safety cable 16 is selected to correspond substantially to the length of the tank 2. The safety cable 16 is made of a material with low mechanical resistance to fire. Typically, the safety cable 16 is made of a material classified D in accordance with European standard EN 13501-1, or a material classified M3 or M4 in accordance with French standard NF P92-507. For example, the safety cable 16 is made of rubber, polyamide, wool, polyester or polypropylene. In particular, the material used for the safety cable 16 is selected according to the predetermined temperature. Thus, the safety cable must break if it experiences a temperature higher than the predetermined temperature for a predetermined period of time, for example a period of time between 10 seconds and 1 hour, preferably between 1 minute and 45 minutes, even more preferably between 10 minutes and 30 minutes. Advantageously, the safety cable 16 is made of elastic material, such as rubber, in order to compensate for any changes in the dimension of the tank as said tank fills up.

[0062] The safety cable 16 is tensioned between on the one hand a static attachment point (not shown) and on the other hand means for attachment 17 to the deformation means 7. According to this first embodiment, the means 17 for attachment to the deformation means 7 are formed by a hook intended to hook onto the striking element of the deformation means 7. For this purpose, the striking element has a ring 18 sized to accommodate the hook. In other embodiments, the safety cable 16 is attached to the deformation means 7 in a different way, for example by gluing, crimping, clipping or welding.

[0063] The second safety member 8 is intended, in the resting position (FIG. 2A), to hold the deformation means 7 in the resting position against a elastic force returning the deformation means 7 back to the deformation position of the first safety member 6 when the second safety member 8 experiences a temperature lower than the predetermined temperature, and, in the working position (FIG. 2B), to release the elastic force for returning the deformation means 7 back to the deformation position of the first safety member 6 when the second safety member 8 experiences a temperature higher than the predetermined temperature.

[0064] The elastic force returning the deformation means 7 back to the deformation position is provided by the compression spring 14. Thus, in the present embodiment, the safety cable 16 is, in the resting position, tensioned so as to compress the spring 14 and to hold the deformation means in the resting position (FIG. 2A). In the working position, the safety cable 16 no longer compresses the spring 14 and thus releases the elastic force thereof for returning the deformation means 7 back to the deformation position (FIG. 2B).

[0065] The opening in the washer 15, which forms a seat for the spring 14, is configured to allow the second safety member 8, and more specifically the safety cable 16, to pass through. The movement of the safety cable 16 relative to the washer 15 is advantageously facilitated by the presence of lubrication means at the opening in the washer. Thus, the risk of friction is reduced between the safety cable 16 and the opening in the washer 15, resulting in a reduction in the kinetic energy with which the deformation means 7 reach the position for deforming the first safety member 6, such a reduction in kinetic energy being likely to prevent deformation of the first safety member 6 and thus render the safety device 3 inoperative.

[0066] An example of operation of the safety device 3 according to the first embodiment of the invention is described below.

[0067] Initially, the tank 2 is not subjected to any heat source, the safety device 3 is therefore in the resting position (FIG. 2A). Thus, the safety cable 16 is intact and holds the striking element of the deformation means 7 in the resting position against the elastic force returning the deformation means 7 back to the deformation position provided by the spring 14. The first safety member 6 is not deformed, that is, in this case the glass bulb is not broken. The first safety member 6 therefore keeps the safety piston 5 in the closure position of the ventilation channel 9. The internal volume 10 of the tank 2 is thus not fluidly connected with the outside of the tank 2.

[0068] In a second step, part of the tank 2 is subjected to a heat source having a temperature higher than the predetermined temperature. For example, in the case where the predetermined temperature is 100 C., this part of the tank is subjected to a heat source having a temperature of 110 C. This heat source is formed for example by a flame. Since the safety cable 16 extends along the entire length of the tank 2, it is subjected to the heat source regardless of the position thereof along the tank 2. As the temperature to which the safety cable 16 is subjected exceeds the predetermined temperature, the safety cable 16 is burnt and breaks, thus passing into a working position wherein it no longer keeps the striking element of the deformation means 7 in the resting position and releases the elastic return force of the spring 14 such that the striking element is propelled by the spring 14 into the deformation position. When the striking element of the deformation means 7 comes into contact with the glass bulb of the first safety member 6, it has sufficient kinetic energy, supplied by the spring 14, to shatter the glass bulb. With the bulb broken, the first safety member 6 no longer keeps the safety piston 5 in the closure position and the spring 13 moves it to the safety position. In this case, complete displacement up to the safety position is facilitated by the presence of the housing 11 in the safety piston 5, which is configured to houses at least part of the striking element of the deformation means 7. When the safety piston 5 moves into the safety position, the ventilation channel 9 is released, fluidly connecting the internal volume 10 of the tank 2 with the outside of the tank 2. The gas contained in the tank 2 therefore escapes to the outside via the ventilation channel 9 thus preventing a pressure build-up inside the tank 2 that could cause said tank to explode. The safety device 3 thus provides a safer tank 2, reducing the risk of explosion in the presence of a heat source.

[0069] With reference to FIGS. 3 to 4, a second embodiment of the invention is described below.

[0070] For this second embodiment, the same numerical references are used for the counterparts of the first embodiment.

[0071] The differences with respect to the first embodiment will be described hereinafter. For identical elements, please refer to the description thereof given above for the first embodiment.

[0072] In the second embodiment, the safety device 3 comprises a third safety member 19 intended to cooperate with the second safety member 8 in such a way as to hold the second safety member 8 in the resting position (FIG. 3A) when the second safety member 8 experiences a temperature lower than the predetermined temperature and to elastically return the second safety member 8 back to the working position (FIG. 3B) when the second safety member 8 experiences a temperature higher than the predetermined temperature.

[0073] The third safety member 19 comprises a body 20 and a tension spring 21. The body 20 has the shape of a hollow box. It is attached to the housing 4 of the safety device 3 at the external opening in the recess comprising the striking element and the spring 14. In the second embodiment, the body 20 fulfills the function of a support seat for the spring 14, which is fulfilled by the washer 15 in the first embodiment. The tension spring 21 is housed inside the body 20 and is attached on the one hand to an internal wall of the body 20 and on the other hand to the means 17 for attaching the second safety member 8 to the deformation means 7. The spring 21 provides the elastic force for returning the second safety member 8 back to the working position.

[0074] The means 17 for attaching the second safety member 8 to the deformation means 7 are different from those of the first embodiment. In place of the hook, they comprise a connecting member comprising two openings following one another along the connecting member, the two openings being in communication. The first opening, known as the rest opening 22, is narrower than the second opening, known as the work opening 23 ([FIG. 4]).

[0075] The striking element of the deformation means 7 is slightly different to that of the first embodiment. It comprises an elongated connecting end with the connecting member and has a reduced-diameter portion able to be housed in the rest opening 22. The striking element is dimensioned so as not to be movable in translation along the longitudinal direction thereof when the reduced portion thereof is housed in the rest opening 22. The striking element is further dimensioned to be movable in translation along the longitudinal direction thereof when the reduced portion thereof is housed in the work opening 23.

[0076] In the resting position, the safety cable 16 is tensioned between its fixed end and its end connected to the means 17 for attachment to the deformation means 7. The third safety member 19 is configured so that the rest tension of the safety cable 16 and the elastic force for returning the second safety member 8 back to the working position provided by the tension spring 21 cooperate in order to hold the second safety member 8 in the resting position. In this position, the reduced portion of the striking element is housed in the rest opening 22 such that the second safety member 8 holds the striking element in the resting position preventing its longitudinal translation and compressing the compression spring 14.

[0077] An example of operation of the safety device 3 according to the second embodiment of the invention is described below.

[0078] Initially, the tank 2 is not subjected to any heat source, the safety device 3 is therefore in the resting position (FIG. 3A). The safety cable 16 is intact and holds the striking element of the deformation means 7 in the resting position against the elastic force returning the deformation means 7 back to the deformation position provided by the spring 14. This holding is achieved because the striking element is housed in the rest opening 22 and is therefore not movable in translation along the longitudinal direction thereof. The first safety member 6 is not deformed, that is, in this case the glass bulb is not broken. The first safety member 6 therefore keeps the safety piston 5 in the closure position of the ventilation channel 9. The internal volume 10 of the tank 2 is thus not fluidly connected with the outside of the tank 2.

[0079] In a second step, the tank 2 is subjected to a heat source having a temperature higher than the predetermined temperature. For example, in the case where the predetermined temperature is 100 C., the tank is subjected to a heat source having a temperature of 110 C. This heat source is formed for example by a flame. Since the safety cable 16 extends along the entire length of the tank 2, it is subjected to the heat source regardless of the position thereof along the tank 2. If the temperature to which the safety cable 16 is subjected exceeds the predetermined temperature, the safety cable 16 burns and breaks. As a result, the tension of the safety cable 16 no longer allows it to be held in the resting position and the tension spring 21 elastically returns the second safety member 8 back to its working position. During this transition to the working position, the reduced portion of the striking element which was previously housed in the rest opening 22, is now housed in the work opening 23, due to the displacement of the connecting member attached to the safety cable 16. Longitudinal translation of the striking element is then permitted as the second safety member 8 no longer holds it in the resting position and releases the elastic return force of the spring 14 so that the striking element is propelled by the spring 14 into the deformation position. When the striking element of the deformation means 7 comes into contact with the glass bulb of the first safety member 6, it has sufficient kinetic energy, supplied by the spring 14, to shatter the glass bulb. With the bulb broken, the first safety member 6 no longer keeps the safety piston 5 in the closure position and the spring 13 moves it to the safety position. In this case, complete displacement up to the safety position is facilitated by the presence of the housing 11 in the safety piston 5, which is configured to houses at least part of the striking element of the deformation means 7. When the safety piston 5 moves into the safety position, the ventilation channel 9 is released, fluidly connecting the internal volume 10 of the tank 2 with the outside of the tank 2. The gas contained in the tank 2 therefore escapes to the outside via the ventilation channel 9 thus preventing a pressure build-up inside the tank 2 that could cause said tank to explode. The safety device 3 thus provides a safer tank 2, reducing the risk of explosion in the presence of a heat source. It should also be noted that the third safety member creates a threshold effect for triggering the deformation means 7. Slight variations in the length of the safety cable 16, for example due to its elasticity and different filling conditions of the tank 2 or even due to creep or loosening of the material of the safety cable 16 under the action of heat or time (aging), will not allow the displacement of the striking element as its reduced portion will always be housed in the rest opening 22 which does not allow longitudinal translation of the striking element. Thus, when the second safety member 8 moves into the working position, the elastic reserve of the spring 14 will not have been depleted and the kinetic energy of the striking element when it reaches the first safety member 6 will be at its maximum. This thus reduces the risk of the safety device 3 failing to switch to the safety position when the second safety element 8 has been subjected to a temperature higher than the predetermined temperature.

[0080] The invention is not limited to the embodiments presented, and other embodiments will become clearly apparent to the person skilled in the art.

LIST OF REFERENCES

[0081] 1: motor vehicle [0082] 2: tank [0083] 3: safety device [0084] 4: housing [0085] 5: safety piston [0086] 5a: seal [0087] 5b: sliding ring [0088] 6: first safety member [0089] 7: deformation means [0090] 8: second safety member [0091] 9: ventilation channel [0092] 10: internal volume of the tank [0093] 11: housing in the safety piston [0094] 12: fixed point for the first safety member [0095] 13: compression spring [0096] 14: compression spring [0097] 15: washer [0098] 16: safety cable [0099] 17: means for attaching the second safety member to the deformation means [0100] 18: ring [0101] 19: third safety member [0102] 20: body of third safety member [0103] 21: tension spring [0104] 22: rest opening of the connecting member [0105] 23: work opening of the connecting member