EP3013438B1 - Method for delivering a liquid pressurised by the combustion gases from at least one pyrotechnic charge - Google Patents

Description

The present invention relates to a method for delivering a liquid contained in a reservoir, said liquid being pressurized by the combustion gases of at least one pyrotechnic charge. It also relates to pyrotechnic charges adapted to the implementation of this method. This method is conveniently implemented for the delivery of a liquid fire extinguishing agent. The process of the invention (and its prior art) is (are) more particularly described in this context. However, this is in no way limiting.

Prior art

Fire extinguishing devices (examples of liquid delivery devices) generally include a reservoir containing an extinguishing agent (liquid agent). Said agent is intended to be diffused over the area of a fire, with a view to extinguishing said fire but also to preventing its spread.

Conventional tank extinguishers are permanently pressurized (they essentially consist of a) a pressurized tank of gas containing the extinguishing agent or b) a pressurized gas cylinder connected to the container of the extinguishing agent ( tank), said bottle, once struck, releasing the pressurizing gas of the extinguishing agent). The use of these extinguishers therefore includes the permanent storage under pressure of an extinguishing agent (variant a) or of a propellant gas for such an extinguishing agent (variant b), with the necessary monitoring operations and verification (such as periodic weighing) that this entails. As the gas pressure (variants a and b) also varies with temperature, the extinguisher's operating temperature range is therefore limited. In general, the operation of such an extinguisher is sensitive to temperature. In addition, during the delivery of the extinguishing agent, the volume available for the gas increases and therefore, the pressure of said gas decreases, causing an inevitable drop in the rate of delivery of the extinguishing agent and a decrease the effectiveness of the diffusion (dispersion or spray or propulsion) of said agent. To alleviate this disadvantage, it is generally expected, a pressure, at the start of delivery (of the extinguishing agent), more important, resulting in an oversizing of the structure of the device and therefore an increase in the weight and an additional cost of the device.

As an alternative to these permanently pressurized devices, devices have been proposed, in particular for fighting fires in aircraft engines, comprising a pyrotechnic gas generator, the pyrotechnic gases generated by said generator being suitable for pressurizing and delivering liquid extinguishing agent. Such devices with a pyrotechnic gas generator are efficient, effective and particularly advantageous in that their use does not involve the storage and management of gas under pressure.

The patent application EP 1 782 861 describes a fire extinguishing device comprising a reservoir of extinguishing agent (liquid) and means for generating a pressurized gas, said means possibly consisting of a pyrotechnic gas generator. A separation element, for example a flexible membrane, is provided to separate said gas generator from said extinguishing agent. During operation of said generator, the membrane deploys under the effect of the pressure of the gases generated and expels the extinguishing agent from the reservoir via a calibrated seal after rupture of said calibrated seal under the effect of the pressure of said extinguishing agent. extinction.

The patent application EP 2 205 325 describes a device comprising a cylindrical body housing a sliding piston, defining on one side a chamber, forming a reservoir, filled with the extinguishing agent (liquid, at its saturated vapor pressure, under a gaseous sky) and the other side, a chamber containing a pyrotechnic gas generator. When the gas generator is actuated, the gas pressure moves the piston so that the extinguishing agent is forced out of the tank.

The patent application WO 2008/025930 describes a pyrotechnic gas generator suitable for operating fire extinguishers of the type mentioned above. The pyrotechnic charge of the generator advantageously consists of at least one monolith block, solid or with a central channel, of large dimensions (uninhibited, ie without inhibitor of combustion on its surface): a cylindrical monolithic block whose two dimensions, thickness and diameter, are between 10 and 75 mm. The composition of this pyrotechnic charge is advantageously based on basic copper nitrate (BCN) and guanidine nitrate (NG).

The patent application WO 2007/113299 also describes substantially cylindrical pyrotechnic objects or blocks of large dimensions, suitable for use in pyrotechnic gas generators for operating fire extinguishers of the type mentioned above. The patent application EP 1552859A1 describes a method for delivering a liquid, contained in a reservoir, said reservoir having at least one orifice for delivering said liquid closed off by an erasable seal under a threshold pressure applied to said liquid.

It is indeed obvious that the pyrotechnic charges (blocks of propellant) used must be of sufficient size to give the gas generator an operating time compatible with the desired extinguishing function. This operating time is greater than that required in the field of automobile safety, more particularly for the operation of airbags and pyrotechnic actuators such as seat belt pre-tensioners and bonnet lift actuators.

The gas flow rate profile generated by such generators is however always very decreasing. On the one hand, the burning surface of the at least one block of propellant concerned decreases during the combustion. On the other hand, as already indicated above, the free volume of the extinguisher increasing as the liquid is expelled, the pressure applied to the liquid drops as said liquid is delivered (d 'where the drop in the delivery rate of said liquid). In this regard, one can consider the figures 1 to 3 of said request WO 2007/113299 . These figures show the continuously and drastically decreasing profile of the pressure applied to the liquid by the gases generated by the combustion of these pyrotechnic charges consisting of such cylindrical propellant blocks. These figures also show that the duration of pressurization is all the longer as the dimensions of the blocks are greater.

Thus, as indicated above, the use of these pyrotechnic charges made up of these blocks of propellant in this type of architecture (extinguishing devices with pyrotechnic gas generators) makes it necessary to oversize the structural elements of the fire extinguisher so that these elements withstand pressure, at the start of delivery of the liquid, high (higher than the average pressure during operation of the extinguisher), in order to ensure sufficient pressure at the end of spraying (despite the pressure drop linked to the very decreasing profile of pressurization).

INVENTION

In such a context, that of the general delivery of a liquid following its pressurization by combustion gases generated pyrotechnically, more particularly that of the operation of extinguishers of the above type, the inventors propose an improvement. This improvement is analyzed in terms of method (optimization of the delivery profile of said liquid) and device (optimization of said delivery profile making it possible to lighten the device (see the over-sizing mentioned above)).

The present invention is as defined in the appended claims.

For all practical purposes, it is indicated here that the delivery time of the pressurized liquid is typically, for an extinguisher, from a few seconds to several tens of seconds.

According to its first object, the present invention therefore relates to a method for delivering a liquid, in particular a liquid extinguishing agent, contained in a reservoir, said reservoir having at least one orifice for delivering said liquid closed by an erasable lid under a threshold pressure applied to said liquid (if several delivery orifices exist, they are each closed by an erasable seal under a threshold pressure of the same intensity). Said erasable seal is advantageously such as to be erased without causing any interference with the progress of the method (i.e. with the operation of the device in which said method is implemented), without in particular generating fragments or debris. It is thus advantageously of the frangible membrane type in the form of petals or a spring valve.

• la combustion d'au moins un chargement pyrotechnique pour générer des gaz de combustion,
• la pressurisation dudit liquide sous l'action desdits gaz de combustion, et
• l'effacement dudit opercule effaçable dudit au moins un orifice de délivrance et la délivrance dudit liquide pressurisé.

Conventionally, said method comprises:

• the combustion of at least one pyrotechnic charge to generate combustion gases,
• pressurizing said liquid under the action of said combustion gases, and
• erasing said erasable seal from said at least one delivery orifice and delivering said pressurized liquid.

Conventionally, said method therefore comprises a transitional phase during which the combustion gases of the pyrotechnic charge ensure the pressurization of the liquid until the removal of the seal from at least one delivery orifice, followed by an "active phase » : that of the delivery of the liquid. In general, the aim is to shorten the duration of this transient phase (which constitutes a time delay between the detection of the event and the response to said event). Note, however, that it cannot be totally excluded from the scope of the invention to knowingly confer on this transitional phase a “substantial” duration; this, in a context of extinguishers for example, with the aim of reproducing the operating conditions of extinguishers of the prior art (with pressurization by gas bottle), conditions to which the user is accustomed. We will come back later to the management of the transitional phase preceding delivery.

Characteristically, a) in the context of the implementation of the method of the invention, the flow of combustion gas generated during the delivery of the liquid ensures an almost constant pressurization of the said liquid and therefore the delivery of the said (pressurized) liquid to almost constant flow. The notion of quasi-constant pressurization is quantified below: the pressure of said liquid, during the delivery of said liquid, varies only at most +/- 30%, advantageously only at most +/- 20%, very advantageously a maximum of +/- 10%, relative to its initial value at the time of the erasure of said seal(s). It has been understood that the almost constant liquid delivery rate is therefore only likely to vary, quite logically, only in the same proportions (maximum of +/- 30%, advantageously maximum of +/- 20%, very advantageously a maximum of +/- 10%, compared to its initial value at the time of the erasure of said seal(s).

It should already be noted here that the delivery of the liquid is advantageously implemented, in dispersed form, via a (spray) nozzle. In such a case, the sensitivity of the delivery rate to pressure variations of said liquid is attenuated (said delivery rate by a nozzle responding, as a rule general, to a law in P ⁿ , with P the pressure of said liquid and n <1). The delivery rate of the liquid by a nozzle, in the liquid pressure variation ranges aroused, is thus likely in fact to vary at most by only +/- 15%, advantageously at most by only +/- 10%, very advantageously at most only +/- 5%. An almost constant pressure, P+/-ΔP, with ΔP as defined in the previous paragraph, makes it possible, under these advantageous liquid delivery conditions, to ensure an almost constant delivery rate, Q+/-ΔQ, with ΔQ such that defined in this paragraph (ΔQ<ΔP), and therefore a quality of spraying, constant, very interesting.

Characteristically, the delivery of the (pressurized) liquid is thus implemented at an almost constant flow rate due to an almost constant pressurization of said liquid. In this, the method of the invention is original. Incidentally, it should be noted here that the delivery of the pressurized liquid at a quasi-constant flow rate implies a (decreasing) variation in the volume occupied by said quasi-constant liquid (of the tank volume) and corresponds to a (increasing) variation in the volume occupied by the quasi-pressurization gases. constant.

Characteristically, b) the method of the invention is implemented in a device comprising said liquid reservoir and at least one pyrotechnic gas generator containing said at least one pyrotechnic charge (the combustion of which generates the combustion gases necessary to liquid pressurization); said at least one pyrotechnic gas generator being connected to said reservoir and a movable member for separating the combustion gases generated and said liquid being provided within said device. The presence of this movable separation member is interesting in several respects. Above all, said movable member contributes to the constancy of the desired pressurization of the liquid (see above), by “balancing” the pressures applied to its surface. Said moving member is also interesting because of the separation function (combustion gas/liquid) that it performs. It may be particularly appropriate to protect the liquid from gases. In any case, the formation of a foam, detrimental to effective delivery of liquid, is to be avoided.

It is not excluded that the device of the invention comprises at least one nozzle (nozzle with a modular neck surface or with a neck surface constant), through which the combustion gases generated are debited (evacuated from said at least one pyrotechnic generator). However, according to a particularly preferred variant embodiment, said device does not contain such a nozzle. The desired result (as regards the quasi-constant pressurization of the liquid) can quite well be achieved without the use of any nozzle (see below). Thus, the device of the invention can be of very simple design.

Also characteristically, c) in the method of the invention, the at least one pyrotechnic charge which is of the solid monolithic block type or of the stack of disks type, has the shape of a right cylinder with a circular section and a lateral surface developing over its entire length between two end faces, said lateral surface being inhibited in combustion over part of the length of the cylinder from one of its end faces by covering with a combustion inhibiting material, which is itself inhibited in combustion by covering with a combustion inhibiting material and not being inhibited in combustion on the complementary part of the length of the cylinder from the other of its end faces which is not not inhibited in combustion, so that during the pressurization of said liquid, said at least one pyrotechnic charge is in frontal and lateral combustion, and during the delivery of said liquid, said at least one pyrotechnic charge is in frontal combustion only.

In view of the comments above, the person skilled in the art has already grasped all the advantage of the method of the invention. The almost constant pressurization avoids the oversizing of the structural elements of the tanks of the prior art (oversizing provided to withstand a high level of pressure at the start of delivery of the liquid, imposed by the decrease in pressure over time) and therefore allows operate in lighter structures (in which the problem of gas/liquid mixtures does not arise). The almost constant delivery rate ensures almost constant efficiency of the liquid delivered throughout the delivery.

• En règle générale, la température des gaz de pressurisation ne varie pas de façon significative pendant la délivrance du liquide. Toutefois, il est possible, en raison par exemple des pertes thermiques d'un dispositif peu isolé thermiquement et mettant donc du temps à se réchauffer, que la température T desdits gaz varie légèrement en croissant (ΔT<100°C) pendant la délivrance du liquide.

To ensure an almost constant pressurization during the delivery of the liquid (see above), it is necessary that the product, of the number of moles N of pressurization gas by the temperature T of said gases, divided by the volume V of the pressurized tank ( NxT/V) is almost constant (not therefore varies only at most +/- 30%, advantageously only at most +/- 20%, very advantageously only at most +/- 10%).

• In general, the temperature of the pressurizing gases does not vary significantly during the delivery of the liquid. However, it is possible, for example due to heat losses from a device that is poorly thermally insulated and therefore takes time to heat up, that the temperature T of said gases varies slightly increasing (ΔT<100°C) during delivery of the liquid.

In such cases (where therefore the temperature of the pressurization gases varies slightly increasing during the liquid delivery phase), to ensure almost constant pressurization of the liquid, it is then necessary that the flow of combustion gas provided by the pyrotechnic charge either slightly decreasing (N↘) during delivery of said liquid; this, in order to compensate for the slight increase in the temperature (T ↗) of the combustion gases, i.e. to ensure a constant NxT/V product.

Certainly, the pyrotechnic charges of the prior art whose combustion surfaces are entirely free (i.e. that the entire surface of said charges is capable of burning), present, during their combustion, a very degressive combustion surface, and are therefore not suitable for generating a slightly decreasing gas flow.

• Veille : m= ρ. Sc. Vc = P. Cd. At (avec Vc = a Pⁿ
• Vc est la vitesse de combustion du propergol en mm/s
• P : la pression en MPa
• ρ : la masse volumique du propergol
• a: le coefficient de pression de la loi de vitesse de combustion
• n: l'exposant de pression de la loi de vitesse de combustion
• At: l'aire du col de ladite tuyère comme indiqué ci-dessus
• Cd=1/C^∗ : le coefficient de débit).

It is possible, for this purpose, to use a means, well known to those skilled in the art, for example as described in the patent application US 2007/0204593 , ie a primed nozzle with a variable neck surface, optionally piloted, at the outlet of a combustion chamber containing the burning pyrotechnic charge (the ΔT is compensated by an adequate ΔN thanks to said nozzle). The surface of the neck of the nozzle At, controlling the internal pressure P in the combustion chamber in correlation with the burning surface Sc of the pyrotechnic charge, therefore controls the combustion rate Vc of the propellant of the pyrotechnic charge, which then delivers the flow rate of gas m of combustion required (the number N of moles required) according to Paul's law

• Standby: m= ρ. Sc. Vc = P. Cd. At (with Vc = a P ⁿ
• Vc is the propellant burn rate in mm/s
• P: the pressure in MPa
• ρ: the density of the propellant
• a: the pressure coefficient of the combustion rate law
• n: the pressure exponent of the burning rate law
• At: the throat area of said nozzle as given above
• Cd=1/C ^∗ : the flow rate coefficient).

A slightly decreasing gas flow can therefore be obtained by combustion of a pyrotechnic charge ("of any geometry") in a combustion chamber equipped with a nozzle with a modular neck section (see above), but the inventors recommend strongly (see below) to obtain such a slightly decreasing gas flow by much simpler means, particularly suited to fire extinguisher contexts.

Originally, the applicant proposes, in the context of the invention, the use of specific pyrotechnic charges, suitable for inducing a slightly decreasing combustion gas flow, the use of pyrotechnic charges having part of their combustion surface inhibited in combustion. Such types of pyrotechnic charges are, to date, used in contexts different from that of the invention, in particular in propulsion. The present invention in fact offers an original outlet, an original use for this type of pyrotechnic charge.

A person skilled in the art generally knows how to inhibit the combustion of part of the combustion surface of a pyrotechnic charge by covering said part with a layer of suitable material (combustion inhibiting material), presenting the most often in the form of a varnish (not combustible). Such combustion inhibition has been described in numerous documents of the prior art and in particular in the patent application FR 2 275 425 and the patent US 5,682,013 .

Those skilled in the art are in fact aware of several types of pyrotechnic charges having part of their combustion surface inhibited in combustion, suitable for generating, by combustion, a slightly decreasing gas flow with, therefore, a slightly decreasing combustion surface.

• les chargements pyrotechniques, qui ont une forme de cylindre droit à section circulaire avec une surface latérale se développant sur toute leur longueur entre deux faces d'extrémité, de type bloc monolithe plein ou de type empilement de disques « quasi parfait » (les disques empilés constituant une structure quasi monolithique) ; seulement une de leur face d'extrémité étant inhibée en combustion. De tels chargements conviennent dans la mesure où ils ne sont susceptibles de brûler que sur leur face latérale et sur une de leur face d'extrémité ;
• les chargements pyrotechniques qui ont une forme tronconique, avec une surface latérale se développant sur toute leur longueur entre deux faces d'extrémité, de type bloc monolithe plein ou de type empilement de disques « quasi parfait » (constituant une structure quasi monolithique) ; leur surface latérale et la face d'extrémité de plus petite section étant inhibée en combustion tandis que l'autre face d'extrémité de plus grande section n'est pas inhibée en combustion. De tels chargements conviennent dans la mesure où ils ne sont susceptibles de brûler qu'en combustion frontale ou combustion en « cigarette conique» ;
• les chargements pyrotechniques, qui ont une forme tubulaire présentant une surface latérale se développant sur toute leur longueur entre deux faces d'extrémité ainsi qu'un canal central cylindrique ou étoilé, de type bloc monolithe plein ou de type empilement de disques « quasi parfait » (constituant une structure quasi monolithique) ; leurs faces d'extrémité étant inhibées (leur surface latérale n'étant pas inhibée). De tels chargements conviennent dans la mesure où ils brûlent dans leur canal (surface interne) et sur leur surface latérale.

Among the pyrotechnic charges suitable for generating, by combustion, a slightly decreasing flow of gas with a surface of slightly decreasing combustion, due to the inhibition in combustion of a part of their combustion surface, we can, without limitation, cite:

• pyrotechnic charges, which have the shape of a straight cylinder with a circular section with a lateral surface developing over their entire length between two end faces, of the solid monolith block type or of the “quasi-perfect” stacking of discs type (the stacked discs constituting an almost monolithic structure); only one of their end faces being inhibited in combustion. Such loads are suitable insofar as they are liable to burn only on their lateral face and on one of their end faces;
• pyrotechnic charges which have a frustoconical shape, with a lateral surface developing over their entire length between two end faces, of the solid monolith block type or of the "quasi-perfect" stack of discs type (constituting a quasi-monolithic structure); their lateral surface and the end face of smaller section being inhibited in combustion while the other end face of larger section is not inhibited in combustion. Such charges are suitable insofar as they are only likely to burn in frontal combustion or combustion in a “conical cigarette”;
• pyrotechnic charges, which have a tubular shape having a lateral surface developing over their entire length between two end faces as well as a cylindrical or star-shaped central channel, of the solid monolith block type or of the “quasi-perfect” stack of discs type (constituting an almost monolithic structure); their end faces being inhibited (their side surface not being inhibited). Such charges are suitable insofar as they burn in their channel (internal surface) and on their lateral surface.

The person skilled in the art is able to optimize, according to the exact characteristics of the device in question, in particular its thermal insulation, the pyrotechnic charges having a part of their combustion surface inhibited in combustion, at a slightly decreasing flow rate, ensuring pressurization almost liquid constant during the delivery phase.

• Dans les autres cas, beaucoup plus fréquents, après la phase transitoire qui contribue à chauffer le dispositif (plus précisément après l'effacement du(des) opercule(s)), i.e. pendant la phase de délivrance dudit liquide), la température des gaz de pressurisation varie de façon non significative. Alors, pour assurer une pressurisation quasi constante du liquide, il suffit que le débit de gaz de combustion apporté par le chargement pyrotechnique soit quasi constant (ne varie qu'au maximum de +/- 30 %, avantageusement qu'au maximum de +/- 20 %, très avantageusement qu'au maximum de +/- 10 %).

The loadings described above were with reference to the active phase. It is easy to conceive that they can present, above all use, a uniform geometry, for a more consequent volume, so that they burn uniformly, successively, at the same time during the transitory phase and during the active phase. It is also possible to provide a binary structure, in particular for an additional load to be secured to said loads described above; said additional charge being intended to burn during the transient phase, advantageously intended to burn so as to shorten said transient phase.

• In the other, much more frequent cases, after the transient phase which contributes to heating the device (more precisely after the removal of the cap(s)), ie during the delivery phase of said liquid), the temperature of the gases pressurization varies insignificantly. Then, to ensure an almost constant pressurization of the liquid, it suffices that the flow of combustion gas provided by the pyrotechnic charge is almost constant (varies only at most by +/- 30%, advantageously only at most by +/- - 20%, very advantageously at a maximum of +/- 10%).

Undoubtedly, an almost constant gas flow can be obtained by combustion of a pyrotechnic charge ("of any geometry") in a combustion chamber equipped with a nozzle with adjustable neck section (see above), but the inventors recommend, here too, strongly to obtain such an almost constant flow of gas by much simpler means, particularly suitable for extinguisher contexts.

An almost constant gas flow can thus be advantageously obtained, without using a nozzle with a modular neck section (see above), with a pyrotechnic charge which burns, at an almost constant combustion pressure (varying only at maximum of +/- 30%, advantageously at a maximum of +/- 20%, very advantageously at a maximum of +/- 10%), presenting (during its combustion, therefore) an almost constant combustion surface . In view of the combustion rate laws of conventional propellants (Vc = a P ⁿ , with n generally between 0 and 0.6), an almost constant combustion surface corresponds, within the meaning of the invention, to a combustion surface only varying at most by +/- 15%, advantageously only at maximum of +/- 10%, very advantageously only at a maximum of +/- 5%.

The almost constant combustion pressure, of a pyrotechnic charge with an almost constant combustion surface, can be ensured either by including the pyrotechnic charge in a volume at almost constant pressure (this is the case, in the context of the invention, of the pressurization volume (insofar as the (increasing) variation of the volume occupied by the pressurization gases corresponds to the (decreasing) variation of the volume occupied by the pressurized liquid, during the delivery of said pressurized liquid), or by including the loading pyrotechnics in a combustion chamber fitted with a nozzle with a constant neck area (the use of such a nozzle (less sophisticated than that of a nozzle with a modular neck section (see above)) is advantageous in that it allows easy adjustment of the pressure).The person skilled in the art knows that the pressure exponent of a propellant constituting a pyrotechnic charge must be less than 1 to ensure a constant combustion rate at constant pressure, advantageously less to 0.8, very advantageously less than 0.6. When said pyrotechnic charge is put into combustion, by including it in a volume at almost constant pressure, without a nozzle, those skilled in the art know that it is preferable, to ensure the consistency of the combustion rate and therefore of the flow rate of gas, to choose a propellant whose pressure exponent is less than 0.3, advantageously less than 0.2, very advantageously less than 0.1.

A quasi-constant combustion surface, suitable for inducing a quasi-constant combustion gas flow at quasi-constant combustion pressure, can itself be obtained with pyrotechnic charges having part of their combustion surface inhibited in combustion.

We have seen above that those skilled in the art know how to inhibit the combustion of part of the combustion surface of a pyrotechnic charge by covering said part with a layer of suitable material (combustion inhibiting material), presenting most often in the form of a varnish (non-combustible), that such inhibition in combustion has been described in numerous documents of the prior art and in particular in the patent application FR 2 275 425 and the patent US 5,682,013 .

Those skilled in the art are in fact aware of several types of pyrotechnic charges having part of their combustion surface inhibited in combustion, suitable for generating, by combustion, a quasi-constant flow of gas at quasi-constant pressure with a quasi-constant combustion surface. Such types of pyrotechnic charges are, to date, also used in contexts different from that of the invention, in particular in propulsion. The present invention proposes, here too, in fact an original outlet, an original use for this type of pyrotechnic charge.

• les chargements pyrotechniques (d'un premier type que l'on peut qualifier de type A, schématisé sur les figures 1 et 1' annexées) qui ont une forme de cylindre droit à section circulaire avec une surface latérale se développant sur toute leur longueur entre deux faces d'extrémité, de type bloc monolithe plein ou de type empilement de disques ; leur surface latérale et une de leurs faces d'extrémité étant inhibées en combustion tandis que l'autre face d'extrémité n'est pas inhibée en combustion. De tels chargements conviennent dans la mesure où ils ne sont susceptibles de brûler qu'en combustion frontale ou combustion en « cigarette » ;
• les chargements pyrotechniques (d'un deuxième type que l'on peut qualifier de type B), qui ont une forme tubulaire, présentant une surface latérale se développant sur toute leur longueur entre deux faces d'extrémité ainsi qu'un canal central cylindrique, de type bloc monolithe plein ou de type empilement de disques « quasi parfait » (les disques empilés constituant une structure quasi monolithique) ; seulement l'une de leurs faces d'extrémité étant inhibée en combustion. De tels chargements brûlent sur leur surface latérale (surface externe), dans leur canal (surface interne) et sur leur face d'extrémité non inhibée ; ces chargements ne sont pas couverts par les revendications ;
• les chargements pyrotechniques (d'un troisième type que l'on peut qualifier de type C), qui ont une forme tubulaire (de diamètre externe D1), présentant une surface latérale se développant sur toute leur longueur entre deux faces d'extrémité ainsi qu'un canal central cylindrique (de diamètre D2), de type bloc monolithe plein ou de type empilement de disques « quasi parfait » (les disques empilés constituant une structure quasi monolithique) ; (seulement) leur surface latérale étant inhibée en combustion et leur longueur étant égale ou environ égale à 1,5 fois leur diamètre externe (D1) plus 0,5 fois le diamètre de leur canal central (D2) ; ces chargements ne sont pas couverts par les revendications ;
• les chargements pyrotechniques (d'un quatrième type que l'on peut qualifier de type D), qui ont une forme tubulaire présentant une surface latérale se développant sur toute leur longueur entre deux faces d'extrémité ainsi qu'un canal central étoilé à au moins 5 branches, de type bloc monolithe plein ou de type empilement de disques « quasi parfait » (constituant une structure quasi monolithique) ; leur surface latérale étant inhibée en combustion. De tels chargements brûlent dans leur canal (surface interne) et sur leurs faces d'extrémité. Ces chargements ne sont pas couverts par les revendications.

Among the pyrotechnic charges suitable for generating, by combustion, an almost constant flow of gas at almost constant pressure with an almost constant combustion surface, due to the combustion inhibition of a part of their combustion surface, it is possible, at non-exhaustive title, quote:

• pyrotechnic charges (of a first type that can be described as type A, schematized on the figures 1 and 1' appended) which have the shape of a right cylinder with a circular section with a lateral surface developing over their entire length between two end faces, of the solid monolith block type or of the stack of discs type; their side surface and one of their end faces being inhibited in combustion while the other end face is not inhibited in combustion. Such charges are suitable insofar as they are only likely to burn in frontal combustion or “cigarette” combustion;
• pyrotechnic charges (of a second type that can be described as type B), which have a tubular shape, having a lateral surface developing over their entire length between two end faces as well as a cylindrical central channel, of the solid monolithic block type or of the “quasi-perfect” stacking of discs type (the stacked discs constituting a quasi-monolithic structure); only one of their end faces being inhibited in combustion. Such charges burn on their lateral surface (external surface), in their channel (internal surface) and on their uninhibited end face; these loads are not covered by the claims;
• pyrotechnic charges (of a third type which can be described as type C), which have a tubular shape (of external diameter D1), having a lateral surface developing over their entire length between two end faces as well as a cylindrical central channel (of diameter D2), of the solid monolithic block type or of the “quasi-perfect” stacking of discs type (the stacked discs constituting a quasi-monolithic structure); (only) their lateral surface being inhibited in combustion and their length being equal or approximately equal to 1.5 times their outer diameter (D1) plus 0.5 times the diameter of their central channel (D2); these loads are not covered by the claims;
• pyrotechnic charges (of a fourth type which can be described as type D), which have a tubular shape having a lateral surface developing over their entire length between two end faces as well as a star-shaped central channel with at least less than 5 branches, of the solid monolithic block type or of the "quasi-perfect" stack of discs type (constituting a quasi-monolithic structure); their lateral surface being inhibited in combustion. Such charges burn in their channel (inner surface) and on their end faces. These loads are not covered by the claims.

Pyrotechnic charges of the first type above (type A) are widely preferred because their architecture is simple and their combustion surface as well as therefore their flow rate of (combustion generated) gases at constant pressure approach an almost perfect constant. In addition, their mode of combustion (frontal combustion or "cigarette" combustion) is particularly suitable for ensuring long-term combustion. Type A pyrotechnic charges are therefore particularly suitable for generating an almost constant gas flow during the liquid delivery phase, or even during the pressurization and liquid delivery phase (see below).

It should be noted here that the pyrotechnic charges mentioned above, in particular those of the types specified above, have been described with reference to the implementation of the “active phase” of the method of the invention: that of the delivery of the liquid. It should therefore be understood that, during the delivery of the liquid, the burning pyrotechnic charge is of type A above. Thus, very advantageously, during the delivery of said liquid, the at least one load pyrotechnic, having the shape of a straight cylinder with a circular section with a lateral surface developing over its entire length between two end faces, of the solid monolith block type or of the stack of discs type, is in frontal combustion only; its side surface and its end face opposite the end face in combustion being inhibited in combustion.

In general, before its use for the implementation of the method of the invention, the at least one pyrotechnic charge (intended to be burned) in fact has an overall structure which comprises a part (a portion) intended to be burned during the transitional phase (preliminary to the delivery phase) and another part (another portion) intended to be burned during the “active phase” (pressurized liquid delivery phase). Thus it can present a uniform overall structure, for a "uniform" combustion during the transient phase and during the "active phase" or present a non-uniform, "more complex", at least binary overall structure, for a priori a different combustion during the transitional phase and during the "active phase".

• selon une première variante de mise en oeuvre du procédé de l'invention, le débit de gaz de combustion généré par le au moins un chargement pyrotechnique est croissant ou croissant puis quasi constant ou quasi constant (Q1), pendant la phase de pressurisation du liquide (phase transitoire se concluant par l'effacement de l'opercule (des opercules)) (et quasi constant pendant la délivrance du liquide) ; et
• selon une deuxième variante de mise en oeuvre du procédé de l'invention, le débit de gaz de combustion généré par le chargement pyrotechnique pendant la phase de pressurisation du liquide est géré, maîtrisé, en vue d'écourter ladite phase de pressurisation du liquide (phase transitoire se concluant par l'effacement de l'opercule (des opercules)) : il est en fait augmenté par rapport au débit Q1 ci-dessus. Ledit chargement présente deux régimes de combustion, le premier assurant un débit « élevé » (augmenté par rapport à Q1) pendant la phase de pressurisation et le second un débit quasi constant pendant la phase de délivrance.

So :

• according to a first implementation variant of the method of the invention, the flow rate of combustion gas generated by the at least one pyrotechnic charge is increasing or increasing then almost constant or almost constant (Q1), during the liquid pressurization phase (transient phase ending with the erasure of the seal(s)) (and almost constant during the delivery of the liquid); And
• according to a second implementation variant of the method of the invention, the flow of combustion gas generated by the pyrotechnic charge during the liquid pressurization phase is managed, controlled, with a view to shortening said liquid pressurization phase ( transient phase ending with the erasure of the lid(s)): it is in fact increased compared to the flow rate Q1 above. Said charge has two combustion regimes, the first ensuring a “high” flow rate (increased with respect to Q1) during the pressurization phase and the second an almost constant flow rate during the delivery phase.

It was indicated above that it is not excluded to wish to confer on the transitory phase a “substantial” duration. Thus, a third variant, according to which the flow rate of combustion gases generated during the pressurization of the liquid is reduced (compared to the flow rate Q1 above) cannot be completely excluded.

For the implementation of the first variant, it is possible in particular to operate, during the two phases (the transient phase and the “active phase”), according to the same mode of combustion, with at least one pyrotechnic charge of uniform structure, advantageously the same “cigarette” combustion mode with at least one type A pyrotechnic charge (see above).

For the implementation of the second and third variants, it has been understood that the at least one pyrotechnic charge has an at least binary structure with a part (a section) which generates combustion gases at an increased (second variant) or reduced rate (Third variant) and another part (another section) generating combustion gases at an almost constant rate during delivery of the liquid, hence the above concept of non-uniform overall structure. It is conceivable that the first section can exist according to many variants, as to its shape (cylindrical, frustoconical, cubic shape, for example), and as to its constitution (full monolithic block, stack of structures such as discs, cylinders or cubes, for example).

Below are specified, in a non-limiting way, modes of operation of the method of the invention according to the second variant above.

When it is desired to shorten the pressurization phase, it is possible to use at least one pyrotechnic charge, having the shape of a right cylinder with a circular section with a lateral surface developing over its entire length between two end faces, of the monolithic block type. full or stack-type discs; its lateral surface inhibited in combustion over a part of the length of the cylinder from one of its end faces, itself inhibited in combustion, not being inhibited in combustion over the complementary part of the length of the cylinder from the other of its end faces uninhibited in combustion. This loading, of type A' (in reference to the loading of type A above; schematized on the picture 2 attached), is, during the pressurization of the liquid (transient phase), in frontal and lateral combustion. Its initial combustion surface, corresponding to the entire uninhibited surface of the cylinder (one of its end faces and part of its lateral surface from said end face) then decreases to be limited to the front surface of the part of the cylinder inhibited. The flow rate of gas generated is thus high during the pressurization phase (the transient phase) to quickly reach the sealing pressure of the lid (of the lids) then constant to ensure the delivery at the desired constant pressure of the liquid.

When it is desired to shorten the pressurization phase, it is also possible to use at least one type A" pyrotechnic charge (also with reference to the type A charge above), which comprises two parts (two sections): a first part (a first section), monobloc (= a solid monolithic block) or not (= stack of structures, such as disks, cylinders or cubes), intended (intended) to burn, during the pressurization of the liquid, which has a speed of combustion at given pressure Vc ₁ =a ₁ P ⁿ ₁ higher than that Vc ₂ =a ₂ P ⁿ ₂ (with advantageously n ₁ >n ₂ , very advantageously n ₁ >>n ₂ ) of the complementary part (of the second section), monobloc (= solid monolithic block) or not (= stack of discs)), of said at least one pyrotechnic charge, intended (intended) to burn (in frontal combustion) during delivery of the liquid. propellants in question, the type A" pyrotechnic charge may thus consist of a first section, on the side of the end face not inhibited in combustion, of a propellant with a high combustion rate Vc ₁ (P) and of a second juxtaposed section of another propellant with a lower combustion rate Vc ₂ (P). The mode of operation of such a pyrotechnic charge is therefore as follows: during the pressurization of the liquid, a (first) part, not inhibited in combustion or of which a part of the combustion surface is inhibited in combustion, of the pyrotechnic charge burns at a high combustion rate to ensure pressurization over a short time of said liquid until the erasure of said seal, then, during the delivery of said liquid, the complementary part of said pyrotechnic charge, having the shape of a right cylinder with a circular section with a lateral surface developing over its entire length between two end faces, of the type solid monolithic block or disk stack type, said side surface and said end face opposite the burning end face being combustion inhibited, burns at a moderate burning rate to ensure delivery of said liquid over a long period of time .

Such a multi-component, at least two-component, pyrotechnic charge therefore generates, with a combustion surface that is constant or not, during the pressurization phase of the liquid, a first flow of gas ensuring pressurization over a short time of said liquid (resulting of the combustion of the first section consisting of at least one propellant with a high combustion rate), making it possible to reach in a short time the pressure for erasing the seal(s), then, during the delivery phase of the liquid, a second flow of gas over a long, constant time, at constant pressure (resulting from the "cigarette" combustion of the second section consisting of a propellant at a lower combustion rate) ensuring the constant pressurization of said liquid for a long time.

It was indicated above that the first part of at least one bi-component loading of type A" can be, at least in part, inhibited (type A"1; schematized on the picture 3 appended) or uninhibited (type A"2; schematized on the figure 4 attached). It is understood that the non-inhibition of the part at high combustion speed is even more favorable to the shortening of the duration of the transient phase. It is also understood that the type A"2 charge corresponds to a type A' charge, consisting for the uninhibited part of its lateral surface of a propellant with a combustion rate Vc ₁ (P) and for the additional inhibited part of its lateral surface of a propellant with a combustion rate Vc ₂ (P): Vc ₁ (P)>Vc ₂ (P).

It is understood that the first section can in fact exist according to numerous variants, as regards, in particular, its shape and its constitution (see above), its number of components (n≥1) and the identical composition or not of said components ( n≥2) (their combustion speed Vc ₁ (P) identical or not; the said speed(s) Vc ₁ (P) being, in any event, greater than that of the second section) ... Said first section advantageously exists according to the same geometry as that of the second section (cylinder with circular section), and, single-component or not, with combustion speed(s) Vc ₁ (P) greater than that of the second section.

It is easily understood that at least two-component pyrotechnic charges of another type (Vc ₁ (P)<Vc ₂ (P): see above) can be used for the implementation of the third variant of the method of the invention, less recommended.

In general, the combustion of at least one pyrotechnic charge can be carried out with an adjustment of the combustion pressure. To this end, said combustion can be carried out in a combustion chamber provided with a nozzle (see above). This variant is advantageous insofar as the combustion pressure of the charge, and therefore its combustion rate, are independent of the pressurization pressure of the liquid, which facilitates the adjustment of operation during the implementation of the method.

It is recalled that the pressurized liquid is advantageously delivered in dispersed form, via a nozzle. The delivery at a constant flow rate of the liquid then allows, via said nozzle, a dispersion of constant quality throughout the delivery phase (see above).

The liquid in question may in particular consist of a (fire) extinguishing agent (water, water+additives, etc.), a lubricating agent, a cooling agent (water, glycol, etc.), a cleaning agent and/or dispersant (surfactant liquid, etc.). It is again emphasized here that the delivery of the liquid at a constant flow rate, according to the method of the invention, ensures a very advantageous supply of a constant quantity of liquid to the recipient, which requires said supply of liquid (i.e. the fire to be extinguished and contained, in a context of issuing an extinguishing agent, i.e. the machine which is heating up, in a context of issuing a lubricating agent, i.e. the pollution to be fought, in a context of issuing of a cleaning and/or dispersing agent, etc.).

As regards the devices suitable for implementing the method of the invention (devices with movable separation member between the liquid reservoir and the pyrotechnic gas generator(s), it can quite well be act of devices described in the prior art, in particular in the patent applications EP 1 782 861 And EP 2 205 325 . It is to the credit of the inventors to have selected this type device (of simple design) for implementing the method of the invention (particularly with reference to the constraints on the pressurization (almost constant) of the liquid and with a view to avoiding any contact between combustion gas/liquid). As indicated above, such devices comprise, in their structure, a reservoir (for the liquid to be delivered) and at least one pyrotechnic gas generator containing at least one pyrotechnic charge; said at least one pyrotechnic gas generator being connected to said reservoir and a movable member for separating the combustion gases generated and said liquid being provided within said device. Such devices comprise, in their basic structure, a tank connected to a gas generator containing a pyrotechnic charge. It is understood that their structure can in fact be more complex, with several generators, arranged, in parallel, upstream of the reservoir; each of said generators containing one or more loads. In any event, one or more generators are liable to discharge into one or more reservoirs. The device is therefore likely to comprise several reservoirs. In any event, the method of the invention is implemented at each of said reservoirs.

The device in question is advantageously a compact device (and therefore of limited size). According to a first variant, such a compact device comprises a one-piece body (in one piece, unitary) in which the reservoir and the at least one pyrotechnic generator are arranged. According to a second variant, within (the structure) of such a compact device, the at least one pyrotechnic generator is arranged in (the volume of the) reservoir.

As regards the movable separation member, we have seen that it can consist of a flexible membrane or a piston. It advantageously consists of a piston.

The method of the invention is thus advantageously implemented in a device according to the first variant above, device which advantageously comprises in its structure a body (monobloc) with sliding piston (= movable separation member); said piston defining two chambers, a first chamber (front) constituting the reservoir and a second chamber (rear) containing at least one pyrotechnic charge constituting a gas generator pyrotechnic. Such a device, not comprising a nozzle, is perfectly suitable for implementing the method of the invention (see above).

The method of the invention can therefore also be implemented in a device according to the second variant above, device which advantageously comprises at least one pyrotechnic generator (generally a single such pyrotechnic generator) arranged in the upper part of the internal volume (vacuum ) of a reservoir containing the liquid to be delivered. A flexible membrane shares the internal volume of the tank (the combustion gases then act on this membrane to act on the liquid) or is associated with said at least one gas generator (the combustion gases inflate such a membrane to act on the liquid) . Such a device, comprising or not comprising nozzle(s), advantageously not comprising any nozzle, is perfectly suitable for implementing the method of the invention (see above).

The method of the invention is thus advantageously implemented in the devices whose exact structure has been recalled above.

• en un initiateur pyrotechnique par sollicitation mécanique ou électrique, générant des gaz chauds à la surface de l'allumeur, ou
• en un initiateur non pyrotechnique par sollicitation mécanique ou électrique, générant un point chaud à la surface de l'allumeur : tel un fil chaud, ou un élément piézoélectrique ; et

que l'allumeur peut consister :

• en un allumeur pyrotechnique type « microroquette », comprenant un chargement pyrotechnique à combustion rapide (type composition propergol double base ou Butalite^®) (masse ~ quelques grammes), disposé dans une chambre de combustion avec tuyère dont le jet est dirigé vers la surface du chargement, et/ou
• en un allumeur constitué d'une ou plusieurs pastilles d'allumage à réaction vive (dont la composition est du type B/KNO₃ ou TiH₂/KClO₄ ou NH₄ClO₄/NaNO₃/liant), disposée sur la surface libre du chargement pyrotechnique, et/ou
• en un allumeur constitué d'une ou plusieurs pastilles (dont la composition est de type nitrate basique de cuivre (BCN)/nitrate de guanidine (NG)).

It is clearly understood that the devices in question also comprise means for initiating combustion, ie an ignition system for at least one pyrotechnic charge, gas generator. Such an ignition system generally comprises an initiator and an igniter. In a non-limiting way, it can be indicated here that the initiator can consist of:

• into a pyrotechnic initiator by mechanical or electrical stress, generating hot gases at the surface of the igniter, or
• into a non-pyrotechnic initiator by mechanical or electrical stress, generating a hot spot on the surface of the igniter: such as a hot wire, or a piezoelectric element; And

that the igniter can consist of:

• into a "micro-rocket" type pyrotechnic igniter, comprising a fast-burning pyrotechnic charge (double-base propellant composition or Butalite ^® type) (mass ~ a few grams), placed in a combustion chamber with a nozzle, the jet of which is directed towards the surface of the loading, and/or
• in an igniter consisting of one or more quick reaction ignition pellets (the composition of which is of the B/KNO ₃ or TiH ₂ /KClO ₄ or NH ₄ ClO ₄ /NaNO ₃ /binder type), placed on the free surface the pyrotechnic charge, and/or
• into an igniter consisting of one or more pellets (whose composition is of the basic copper nitrate (BCN)/guanidine nitrate (NG) type).

It is understood that, during the transient phase (pressurization phase), the pyrotechnic igniter also contributes to the generation of gas. It can be sized to contribute in a non-negligible way to the supply of gas during said transient phase, in particular when it is desired to shorten said transient phase.

As regards the composition of the pyrotechnic charges useful for the implementation of the process of the invention, the indications below can be given, in no way limiting.

This composition is advantageously of the type of that of the pyrotechnic charges used in gas generators for airbags. It is however recalled here that the pyrotechnic charges useful for the implementation of the method of the invention have dimensions adapted to the intended operating time (i.e. greater than those of the pyrotechnic charges used in the gas generators for airbags) .

This composition is advantageously optimized with reference to numerous parameters, such as the combustion temperature, the gas yield, the toxicity of the combustion gases as well as the pyrotechnic safety.

• au moins un composant oxydant choisi parmi les nitrates, tels le nitrate basique de cuivre, le nitrate de sodium, le nitrate d'ammonium, les perchlorates, tels le perchlorate d'ammonium, le perchlorate de potassium, les dinitroamidures, tel le dinitroamidure d'ammonium (ADN), et les oxydes métalliques, tel l'oxyde ferrique ; et
• au moins un composant réducteur azoté choisi parmi le nitrate de guanidine, la nitroguanidine, le guanyl urée dinitramide, le tétrazole, ses dérivés et leurs sels, tels le 5-aminotétrazole, le 5-guanylaminotétrazole, le sel de potassium du 5-aminotétrazole, le sel de sodium du 5-aminotétrazole,le sel de calcium du 5-aminotétrazole, le sel d'ammonium du bitétrazole, le sel de sodium du bitétrazole, le sel d'ammonium de la bitétrazolamine, le sel de sodium du 5,5'-azobitétrazole, le sel de calcium du 5,5'-azobitétrazole, les triazoles, les dinitramides, les diamides et les nitrates de polyamine.

Thus, the composition of at least one pyrotechnic charge, generating pressurization gases in the context of the implementation of the method of the invention, advantageously contains:

• at least one oxidizing component chosen from nitrates, such as basic copper nitrate, sodium nitrate, ammonium nitrate, perchlorates, such as ammonium perchlorate, potassium perchlorate, dinitroamides, such as dinitroamide d ammonium (DNA), and metal oxides, such as ferric oxide; And
• at least one nitrogen reducing component chosen from guanidine nitrate, nitroguanidine, guanyl urea dinitramide, tetrazole, its derivatives and their salts, such as 5-aminotetrazole, 5-guanylaminotetrazole, the potassium salt of 5-aminotetrazole, 5-aminotetrazole sodium salt, 5-aminotetrazole calcium salt, bitetrazole ammonium salt, bitetrazole sodium salt, bitetrazolamine ammonium salt, 5,5 '-azobitetrazole, calcium salt of 5,5'-azobitetrazole, triazoles, dinitramides, diamides and polyamine nitrates.

• au moins un catalyseur balistique, avantageusement choisi parmi les oxydes de cuivre, de fer, de manganèse, de cobalt, d'aluminium, de titane, de zirconium, de zinc et de magnésium ; et/ou
• au moins un agent mouillant, avantageusement choisi parmi les organosilanes et les titanates, très avantageusement choisi parmi le vinyltris-(2-méthoxyéthoxy)silane, le tris-(3-triméthoxysilylpropyl)isocyanurate, le γ-glycidoxypropyltriméthoxy-silane, le diéthoxydiacétoxysilane, le diacétoxydiéthoxysilane et le dibutoxyéthoxyméthylsilane ; et/ou

• au moins un agent agglomérant, avantageusement choisi parmi l'oxyde de silicium et l'alumine ; et/ou
• au moins un auxiliaire de fabrication, avantageusement choisi parmi l'acide carboxylique, le stéarate de calcium, la silice et le mica ;et/ou
• un liant, avantageusement choisi parmi les liants hydrocarbonés oxygénés renfermant un élastomère ou une gomme et un plastifiant (tel que notamment décrit dans la demande de brevet EP 1 216 977 ), les liants hydrocarbonés oxygénés obtenus par réticulation d'un élastomère en présence d'un agent réticulant et d'un plastifiant dont la masse moléculaire est supérieure à 350 g/mol et la balance en oxygène égale ou supérieure à -230 % (tels que notamment décrits dans la demande de brevet EP 2 139 828 ) , un liant PVC (polychlorure de vinyle), un liant silicone, un liant cellulosique, un liant PVA (polyacétate de vinyle).

Said composition of at least one pyrotechnic charge optionally further contains:

• at least one ballistic catalyst, advantageously chosen from copper, iron, manganese, cobalt, aluminum, titanium, zirconium, zinc and magnesium oxides; and or
• at least one wetting agent, advantageously chosen from organosilanes and titanates, very advantageously chosen from vinyltris-(2-methoxyethoxy)silane, tris-(3-trimethoxysilylpropyl)isocyanurate, γ-glycidoxypropyltrimethoxy-silane, diethoxydiacetoxysilane, diacetoxydiethoxysilane and dibutoxyethoxymethylsilane; and or

• at least one agglomerating agent, advantageously chosen from silicon oxide and alumina; and or
• at least one manufacturing auxiliary, advantageously chosen from carboxylic acid, calcium stearate, silica and mica; and/or
• a binder, advantageously chosen from oxygenated hydrocarbon binders containing an elastomer or a rubber and a plasticizer (as described in particular in the patent application EP 1 216 977 ), oxygenated hydrocarbon binders obtained by crosslinking an elastomer in the presence of a crosslinking agent and a plasticizer whose molecular weight is greater than 350 g/mol and whose oxygen balance is equal to or greater than -230% (such as that in particular described in the patent application EP 2 139 828 ), a PVC binder (polyvinyl chloride), a silicone binder, a cellulosic binder, a PVA binder (polyvinyl acetate).

Pyrotechnic charges, the composition of which contains such ingredients and capable of being used in the context of the implementation of the method of the invention, have in particular been described in the patent documents below: US 5,608,183 , US 6,143,102 , FR 2 975 097 , FR 2 964 656 , FR 2 950 624 , FR 2 915 746 , FR 2 902 783 , FR 2 899 227 , FR 2 892 117 , FR 2 891 822 , FR 2 866 022 , FR 2 772 370 And FR 2 714 374 .

The pyrotechnic charges useful for implementing the process of the invention are obtained in a conventional manner, therefore advantageously from the ingredients listed above.

They can be obtained by a wet process. According to a variant, the method comprises the extrusion of a paste containing the constituents of the charge. According to another variant, the process comprises a step of bringing all (or some of) the constituents into aqueous solution (said step of placing into aqueous solution comprising solubilization of at least one of said main constituents (oxidant and/or or reducer)), obtaining a powder by drying by atomization of the solution obtained, the (possible) addition to said powder of the constituent(s) which would not have been put into solution, then shaping the powder by dry compression to obtain pyrotechnic objects.

The pyrotechnic charges of the invention can also be obtained (directly) by a dry process. According to a variant, such a method can be limited to a simple compression of the powder obtained by mixing the constituents, to obtain blocks. According to another variant, such a method may comprise roller compacting, followed by granulation, then shaping of the granules, in order to obtain objects. This variant is described in particular in the patent application WO 2006/134311 .

The pyrotechnic charges useful for carrying out the process of the invention can also be obtained according to other conventional processes comprising mixing in a blade or twin-screw mixer a composition containing a binder for obtaining a paste, then extruding or casting said paste into molds to obtain objects.

With regard to multi-component charges, generally two-component, they may result from the juxtaposition (stacking) of several charges prepared beforehand.

To obtain pyrotechnic charges which have part of their surface inhibited in combustion, the procedure is also conventional, for example by varnishing their surface to be inhibited.

Among the pyrotechnic charges which have part of their (combustion) surface inhibited in combustion, described above as being suitable for the implementation of advantageous variants of the method of the invention, some are new and particularly advantageous. They constitute another object of the present invention.

It should already be noted that obtaining them poses no particular difficulty. They can be obtained by the processes by analogy mentioned above (wet process, dry process or process with the intervention of a binder, to obtain one or more blocks, then inhibition in combustion of part of the surface of said block or of the stack of several blocks).

The pyrotechnic charges in question are in particular types A' and A" specified above (respectively illustrated on the figure 2 (type A'), 3 (type A"1) and 4 (type A"2) attached).

• pour un chargement de type A', d'un chargement pyrotechnique, présentant une forme de cylindre droit à section circulaire avec une surface latérale se développant sur toute sa longueur entre deux faces d'extrémité, de type bloc monolithique plein ou de type empilement de disques ; l'une de ses deux faces d'extrémité étant inhibée en combustion, l'autre de ses deux faces d'extrémité n'étant pas inhibée en combustion et sa surface latérale n'étant inhibée en combustion que sur une partie de sa longueur à partir de ladite face d'extrémité inhibée en combustion. On visualise parfaitement un chargement de ce type sur la figure 2 annexée ;
• pour un chargement de type A", d'un chargement pyrotechnique, qui présente une forme de cylindre droit à section circulaire avec une surface latérale se développant sur toute sa longueur entre deux faces d'extrémité, l'une de ses deux faces d'extrémité et au moins une partie de sa surface latérale à partir de ladite face d'extrémité étant inhibées en combustion, l'autre de ses deux faces d'extrémité n'étant pas inhibée en combustion et qui est constitué de deux tronçons juxtaposés, présentant des vitesses de combustion à pression donnée différentes, le premier tronçon, de type bloc monolithique plein ou de type empilement de structures, telles des disques ou des cylindres, avec une face d'extrémité non inhibée en combustion correspondant à ladite face d'extrémité non inhibée en combustion dudit cylindre droit et une surface latérale correspondant à une partie de ladite surface latérale dudit cylindre droit, au moins en partie inhibée (le chargement est alors un chargement de type A"1) ou non (le chargement est alors un chargement de type A"2) en combustion, ayant une vitesse de combustion à pression donnée (Vc₁=a₁Pⁿ ₁) plus élevée que celle (Vc₂=a₂Pⁿ ₂) du second tronçon (de par des coefficients de pression et/ou des exposants de pression différents), de type bloc monolithique plein ou de type empilement de disques. On visualise parfaitement des chargements de ce type (présentant une forme globale de cylindre droit à section circulaire, avec un premier tronçon de structure mono-composant) sur les figures 3 et 4 ci-après. On a ici privilégié la forme cylindrique.

It is therefore :

• for a type A' charge, of a pyrotechnic charge, having the shape of a straight cylinder with a circular section with a lateral surface developing over its entire length between two end faces, of the solid monolithic block type or of the stack of discs; one of its two end faces being inhibited in combustion, the other of its two end faces not being inhibited in combustion and its lateral surface being inhibited in combustion only over part of its length at from said combustion inhibited end face. A load of this type is perfectly visualized on the figure 2 annexed;
• for a type A" charge, of a pyrotechnic charge, which has the shape of a right cylinder with a circular section with a lateral surface developing over its entire length between two end faces, one of its two faces end and at least part of its lateral surface from said end face being inhibited in combustion, the other of its two end faces not being inhibited in combustion and which consists of two juxtaposed sections, having combustion speeds at different given pressure, the first section, of the solid monolithic block type or of the stack of structures type, such as disks or cylinders, with an end face not inhibited in combustion corresponding to said end face not inhibited in combustion of said right cylinder and a side surface corresponding to a part of said side surface of said right cylinder, at least partly inhibited (the charge is then a type A"1 charge) or not (the charge is then a charge of type A"2) in combustion, having a combustion rate at given pressure (Vc ₁ =a ₁ P ⁿ ₁ ) higher than that (Vc ₂ =a ₂ P ⁿ ₂ ) of the second section (due to pressure coefficients and/or different pressure exponents), of solid monolithic block type or of disk stack type. Loads of this type are perfectly visualized (presenting an overall shape of a right cylinder with a circular section, with a first section of single-component structure) on the figures 3 and 4 below. The cylindrical shape has been favored here.

These loads burn, according to the advantageous “cigarette” combustion mode (see above).

It is now proposed to consider various aspects of the invention with reference to the appended figures.

THE figures 1, 1' , 2, 3 and 4 schematically show, in section, pyrotechnic charges suitable for the implementation (of advantageous variants) of the method of the invention.

THE figure 1.1 , 2.1 and 3.1 schematically show (without taking into account the ignition phase of the pyrotechnic charge) the evolutions of the gas flows (of combustion generated), pressures in the tank (of liquid) and flow of liquid (pressurized delivered), during the setting implementation of the method of the invention with combustion of, respectively, the pyrotechnic charges of the figure 1 or 1' , 2 and 3 .

There figure 2.2 schematically shows the evolution of the combustion surface (Scombustion) during the combustion of the pyrotechnic charge of the picture 2 .

THE figures 1A, 1B and 1C show schematically, in section, devices, charged with the pyrotechnic charge of the figure 1 and in the liquid L to be delivered, suitable for the implementation of variants of the method of the invention.

The loads shown schematically on the figures 1, 1' , 2, 3 and 4 as well as the theoretical curves shown on the figure 1.1 , 2.1 and 2.2 are, in a context of combustion of said loads where the temperature of the pressurizing gases is constant.

There figure 1 shows a pyrotechnic charge 7 of type A not covered by the claims. This load, of cylindrical shape, of length I, is a monolith block. It is inhibited in combustion by the varnish 8 over its entire surface, except on one of its end faces. There figure 1' shows a 7' pyrotechnic charge, of the same type, similarly inhibited, not monolithic, but consisting of a stack of several discs.

The loads of figures 1 and 1' have a constant combustion surface (corresponding to the surface of their circular section). They burn in frontal combustion (in “cigarette” combustion).

It is easy to understand that the flow rate of (combustion) gases generated is increasing then almost constant during the pressurization phase (the combustion pressure increasing) then almost constant during the liquid delivery phase (at constant combustion pressure); there figure 1.1 schematically shows this flow time profile. As regards the pressure in the tank, it starts by increasing until it reaches the pressure at which the liquid is delivered (transient phase), the threshold pressure where the cover 3 is erased (see the figures 1A to 1C ). Beyond this threshold pressure, the pressure is constant. Under the effect of this constant pressure, the liquid is delivered at a constant rate.

On the figures 1A, 1B and 1C , the same elements carry the same references.

The devices shown, preferred for implementing the method of the invention (see above), are respectively referenced 100, 101 and 102. Their unitary structure (in one piece, one-piece) is respectively delimited by a body 100', 101' and 102'.

Devices 100, 101, 102 comprise a reservoir 1, containing the liquid L. Said reservoir 1 has a delivery orifice 2 (of said liquid L), closed by an erasable cover 3 (for example of the frangible membrane type in the form of petals or spring valve). We note the presence of a gaseous sky above said liquid L.

The devices 100, 101, 102 comprise a pyrotechnic gas generator, respectively referenced 15 ( Figure 1A ), 16 ( figure 1B ) and 17 ( figure 1C ). The generators shown are actually of three types. Each of said generators contains a pyrotechnic charge 7, of the type shown in the figure 1 (ie inhibited by the varnish 8 over its entire surface, except on its end face intended to be initiated in combustion by an ignition system (not shown)).

Between each of said generators 15, 16 and 17 and the reservoir 1, there is the piston 4 (movable separation member), capable of sliding in a sealed manner (see seals 4'), under the action of the pressurizing gases generated by combustion of the load 7.

On the Figure 1A , reference 9a is the combustion chamber of the generator 15. This combustion chamber 9a corresponds to the expansion chamber 9'a of the gases generated. We fully understand that such an arrangement allows the implementation within the generator 15 of a combustion at constant pressure (in “active phase” the volume of liquid delivered corresponding to the volume of gas generated).

On the figure 1B , the combustion chamber 9b is delimited by a nozzle 10 with a constant neck surface. Said nozzle 10 allows “fine” adjustment of the pressurization gas flow in the expansion chamber 9′a and therefore of the pressure exerted on the piston 4 and therefore of the liquid delivery flow (during the “active phase”) .

On the figure 1C , the combustion chamber 9C is connected to the gas expansion chamber 9'c by the pipe 11. It is also perfectly understood that such an arrangement allows the implementation within the generator 17 of a combustion at constant pressure (in “active phase” the volume of liquid delivered corresponding to the volume of gas generated).

There picture 2 shows a pyrotechnic charge 70 of type A'. This load 70, of cylindrical shape, of length I, is a monolith block. It is inhibited in combustion by the varnish 80 on one of its end faces 70c as well as on only a part (corresponding to a length l2) of its lateral surface 70a, from said end face 70c. It is not inhibited on its other end face 70b. It is therefore also not inhibited on the complementary part of its lateral surface 70a (corresponding to the length l2; I=l1+l2).

With a load of this type, the combustion is, first of all (during the transient phase), frontal and lateral then (during the liquid delivery phase) only frontal (frontal combustion = “in cigarette”). It is therefore understood that said transitional phase (of pressurization of the combustion chamber) is shortened compared to that obtained with a load, as represented on the figure 1 , insofar as during said transient phase, the combustion surface is more consistent.

The variation of said combustion surface is schematized on the figure 2.2 .

The curves of the figure 2.1 show the variation of the gas flow during the transient phase (said flow decreases as the consumption of the uninhibited lateral surface) then its constancy during the "active phase"("cigarettecombustion" over the length l2), the "rapid" increase in the pressure in the tank during the said transient phase then its constancy during the said "active phase" as well as the constancy of the liquid flow rate during the said "active phase"("cigarettecombustion" on the length l2).

There picture 3 shows a load 700 of type A"1 not covered by the claims.

This load 700, of cylindrical shape, of length I, consists of two juxtaposed cylindrical blocks (sections or parts) 702 and 701. It is inhibited by the varnish 800 on one of its end faces 700c and over its entire side surface 700a. It is not inhibited on its other end face 700b which also corresponds to the end face 701b of block 701. The side surface 701a of said block 701, which corresponds to part of the side surface 700a of the load 700 ( = 701 + 702), is also inhibited. The combustion of said load, successively of its constituent blocks 701 and 702, is therefore a “cigarette combustion”, successively during the transient phase and during the “active phase”. To shorten the duration of said transitional phase, said block 701 has a combustion speed Vc ₁ (P) greater than the combustion speed Vc ₂ (P) of block 702.

There figure 3.1 shows the constancy of the gas flow rates during the two successive phases (“cigarette” combustions), the flow rate during the transient phase increasing then becoming greater than the flow rate during the “active phase”, due to Vc ₁ >Vc ₂ . The reservoir pressure increases rapidly during said transient phase. The constancy of said pressure and therefore that of the flow rate of liquid delivered is then observed (“during the active phase”).

There figure 4 shows a 700' type A"2 load.

This figure shows the references of the picture 3 with a "'". Indeed the referenced elements of figures 3 and 4 correspond. We have already understood that the only difference between the loadings of the figures 3 and 4 (both of cylindrical shape) is the non-inhibition in combustion of the side surface 701'a of the block 701' at combustion rate Vc ₁ , with Vc ₁ (P)>Vc ₂ (P). The combustion of the block 701' is therefore frontal and lateral (just like that of the first part of the load 70 of the picture 2 ). We understand that variations in gas flows, tank pressure and liquid flow, during the combustion of the 700' charge of the figure 4 are of the type shown in the figure 2.1 , with a faster rise in reservoir pressure. The effects of the rapid combustion rate Vc ₁ and of frontal and lateral combustion are combined.

Claims (8)

1. A method for delivering a liquid (L) contained in a reservoir (1), said reservoir (1) having at least one port (2) for delivering said liquid (L) which is closed off by a blow-out disk (3) that is removable at a threshold pressure applied to said liquid (L), comprising:

   - the combustion of at least one pyrotechnic charge (70) in order to generate combustion gases,

   - the pressurization of said liquid (L) under the action of said combustion gases, and

   - the removal of said removable blow-out disk (3) from said at least one delivery port (2) and the delivery of said pressurized liquid (L),

   characterized in that the flow rate of generated combustion gases during the delivery of said liquid (L) ensures a virtually constant pressurization of said liquid (L) and thus the delivery of said liquid (L) at a virtually constant flow rate; the pressure of said liquid (L) during the delivery of said liquid varying only by a maximum of +/-30%, advantageously only by a maximum of +/-20%, very advantageously only by a maximum of +/-10% with respect to its initial value at the time at which said blow-out disk(s) (3) is (are) removed; and

   in that it is implemented in a device (100; 101; 102) comprising said reservoir (1) and at least one pyrotechnic gas generator (15; 16; 17) containing said at least one pyrotechnic charge (70); said at least one pyrotechnic gas generator (15; 16; 17) being connected to said reservoir (1) and a mobile member (4) for separating the generated combustion gases and said liquid (L) being provided within said device (100; 101; 102); and

   in that said at least one pyrotechnic charge (70) which is of the solid monolithic block type or of the stack of disks type, has the shape of a right cylinder with a circular section and a lateral surface (70a) extending along its entire length between two end faces (70b and 70c), said lateral surface (70a) being combustion-inhibited along a part of the length of the cylinder starting from one of its end faces (70c) by covering with a combustion inhibiting material, which is itself combustion inhibited by covering with a combustion inhibiting material and not being combustion-inhibited along the complementary part of the length of the cylinder starting from the other of its end faces (70b) which is not combustion-inhibited, so that during the pressurization of said liquid (L), said at least one pyrotechnic charge (70) is end-burning and side-burning, and during the delivery of said liquid (L), said at least one pyrotechnic charge (70) is end-burning only.
2. The method as claimed in claim 1, characterized in that the combustion of said at least one pyrotechnic charge (70) is implemented with the combustion pressure being regulated.
3. The method as claimed in any one of claims 1 or 2, characterized in that said pressurized liquid (L) is delivered in a dispersed form.
4. The method as claimed in any one of claims 1 to 3, characterized in that said liquid (L) is a fire extinguishing agent, a lubricant, a cooling agent, or a cleaning and/or dispersant agent.
5. The method as claimed in any one of claims 1 to 4, characterized in that said device (100; 101; 102) comprises a one-piece body (100'; 101'; 102') in which said reservoir (1) and said at least one gas generator (15, 16, 17) are arranged, or in that, within said device, said at least one gas generator is arranged in said reservoir.
6. The method as claimed in any one of claims 1 to 5, characterized in that said device (100; 101; 102) comprises a body (100'; 101'; 102') with a sliding piston as the mobile separating member (4); said piston (4) delimiting two chambers, a first chamber that forms said reservoir (1) and a second chamber that contains said at least one pyrotechnic charge (70) forming a pyrotechnic gas generator (15; 16; 17).
7. The method as claimed in any one of claims 1 to 6, characterized in that the composition of said at least one pyrotechnic charge (70) contains:

   - at least one oxidizing component chosen from the nitrates, such as basic copper nitrate, sodium nitrate, ammonium nitrate, the perchlorates, such as ammonium perchlorate, potassium perchlorate, the dinitramides, such as ammonium dinitramide, and the metal oxides, such as ferric oxide; and

   - at least one nitrogenous reducing component chosen from guanidine nitrate, nitroguanidine, guanylurea dinitramide, tetrazole, derivatives of the latter and salts thereof, such as 5-aminotetrazole, 5-guanylaminotetrazole, the potassium salt of 5-aminotetrazole, the sodium salt of 5-aminotetrazole, the calcium salt of 5-aminotetrazole, the ammonium salt of bitetrazole, the sodium salt of bitetrazole, the ammonium salt of bitetrazolamine, the sodium salt of 5,5'-azobitetrazole, the calcium salt of 5,5'-azobitetrazole, the triazoles, the dinitramides, the diamides and the polyamine nitrates.
8. A pyrotechnic charge (70), suitable for implementing the method as claimed in any one of claims 1 to 7, having the shape of a right cylinder with a circular cross section and having a lateral surface (70a) extending along its entire length (l) between two end faces (70b, 70c), of the solid monolithic block type or of the stack of disks type, characterized in that one (70c) of its two end faces (70b, 70c) is combustion-inhibited, while the other (70b) of its two end faces (70b, 70c) is not combustion-inhibited, and its lateral surface (70a) is combustion-inhibited only along a part of its length (l2) starting from said combustion-inhibited end face (70c).

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