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

Abstract

A method for delivering a liquid contained in a reservoir, the reservoir having a port for delivering the liquid which is closed off by a blow-out disk that is removable at a threshold pressure applied to the liquid, includes: the combustion of a pyrotechnic charge to generate combustion gases, the pressurization of the liquid by the combustion gases, and the removal of the removable blow-out disk from the delivery port and the delivery of the pressurized liquid. The flow rate of generated combustion gases during the delivery of the liquid ensures virtually constant pressurization of the liquid and thus the delivery of the liquid at a virtually constant flow rate. The pressure of the liquid during the delivery of the liquid varying only by a maximum of +/30% with respect to its initial value at the time at which the blow-out disk is removed.

Claims

1. A method for delivering a liquid contained in a reservoir, said reservoir having at least one delivery port for delivering said liquid which is closed off by a blow-out disk that is removable at a threshold pressure applied to said liquid, comprising: carrying out a combustion of at least one pyrotechnic charge in order to generate combustion gases; pressurizing said liquid under the action of said combustion gases, and removing said removable blow-out disk from said at least one delivery port and delivering said pressurized liquid, wherein a flow rate of generated combustion gases during the delivery of said liquid ensures a virtually constant pressurization of said liquid, a pressure of said liquid during the delivery of said liquid varying only by a maximum of +/30% with respect to its initial value at a time at which said blow-out disk is removed, and thus the delivery of said liquid at a virtually constant flow rate, a flow rate of said liquid during the delivery of said liquid varying only by a maximum of +/30% with respect to its initial value at a time at which said blow-out disk is removed, wherein said method is implemented in a device comprising said reservoir and at least one pyrotechnic gas generator containing said at least one pyrotechnic charge said at least one pyrotechnic gas generator being connected to said reservoir and a mobile member for separating the generated combustion gases and said liquid being provided within said device, and wherein the at least one pyrotechnic charge, which is of the solid monolithic block type or of the stack of disks type, has a shape of a right cylinder with a circular cross section and a lateral surface extending along its entire length between two end faces, the lateral surface being combustion-inhibited along a part of the length of the cylinder starting from one of the two end faces, which is itself combustion-inhibited, and not being combustion-inhibited along the complementary part of the length of the cylinder starting from the other end face of the two end faces which is not combustion-inhibited, so that during the pressurization of said liquid, said at least one pyrotechnic charge is end-burning and side-burning while during the delivery of said liquid the at least one pyrotechnic charge is end-burning only.

2. The method as claimed in claim 1, wherein the combustion of said at least one pyrotechnic charge is implemented with the combustion pressure being regulated.

3. The method as claimed in claim 1, wherein said pressurized liquid is delivered in a dispersed form.

4. The method as claimed in claim 1, wherein said liquid is a fire extinguishing agent, a lubricant, a cooling agent, or a cleaning and/or dispersant agent.

5. The method as claimed in claim 1, wherein said device comprises a one-piece body in which said reservoir and said at least one gas generator are arranged, or wherein, within said device, said at least one gas generator is arranged in said reservoir.

6. The method as claimed in claim 1, wherein said device comprises a body with a sliding piston as the mobile member; said piston delimiting two chambers, a first chamber that forms said reservoir and a second chamber that contains said at least one pyrotechnic charge forming the pyrotechnic gas generator.

7. A pyrotechnic charge, suitable for implementing the method as claimed in claim 1, having a shape of a right cylinder with a circular cross section and having a lateral surface extending along its entire length between two end faces, of the solid monolithic block type or of the stack of disks type, wherein one of the two end faces is combustion-inhibited, while the other of the two end faces is not combustion-inhibited, and the lateral surface is combustion-inhibited only along a part of its length starting from said combustion-inhibited end face.

8. The method as claimed in claim 1, wherein the pressure of said liquid during the delivery of said liquid varies only by a maximum of +/20% with respect to its initial value at the time at which said blow-out disk is removed.

9. The method as claimed in claim 1, wherein the pressure of said liquid during the delivery of said liquid varies only by a maximum of +/10% with respect to its initial value at the time at which said blow-out disk is removed.

Description

(1) Different aspects of the invention will now be considered with reference to the appended figures.

(2) FIGS. 1, 1, 2, 3 and 4 schematically show, in cross section, pyrotechnic charges suitable for implementing (advantageous variants) of the method according to the invention.

(3) FIGS. 1.1, 2.1 and 3.1 schematically show (without taking the ignition phase of the pyrotechnic charge into consideration) the changes in the flow rates of (generated combustion) gases, pressures in the (liquid) reservoir and the flow rate of (delivered pressurized) liquid, during the implementation of the method according to the invention with combustion of the pyrotechnic charges in FIG. 1 or 1, 2 and 3, respectively.

(4) FIG. 2.2 schematically shows the change in the combustion surface (Scombustion) during the combustion of the pyrotechnic charge in FIG. 2.

(5) FIGS. 1A, 1B and 1C schematically show, in cross section, devices, loaded with the pyrotechnic charge in FIG. 1 and with the liquid L to be delivered, that are suitable for implementing variants of the method according to the invention.

(6) The charges schematically shown in FIGS. 1, 1, 2, 3 and 4 and the theoretical curves shown in FIGS. 1.1, 2.1 and 2.2 are shown in a context of combustion of said charges where the temperature of the pressurizing gases is constant.

(7) FIG. 1 shows a pyrotechnic charge 7 of type A. This charge, which has a cylindrical shape, of length l, is a monolithic block. It is combustion-inhibited by the varnish 8 on its entire surface, apart from at one of its end faces. FIG. 1 shows a pyrotechnic charge 7, of the same type, which is inhibited in a similar manner and is not monolithic but consists of a stack of several disks.

(8) The charges in FIGS. 1 and 1 have a constant combustion surface (corresponding to the surface of their circular cross section). They burn in an end-burning manner (in a cigarette-type manner).

(9) It will easily be understood that the flow rate of generated (combustion) gases increases, is then virtually constant during the pressurization phase (with the combustion pressure increasing) and is then virtually constant during the delivery phase of the liquid (at a constant combustion pressure); FIG. 1.1 schematically shows this time profile of flow rate. As far as the pressure in the reservoir is concerned, it starts by increasing until it reaches the pressure at which the liquid is delivered (transitional phase), the threshold pressure at which the blow-out disk 3 is removed (see FIGS. 1A to 1C). Above this threshold pressure, the pressure is constant. Under the effect of this constant pressure, the liquid is delivered at a constant flow rate.

(10) In FIGS. 1A, 1B and 1C, the same elements bear the same references.

(11) The devices depicted, which are preferred for implementing the method according to the invention (see above) bear the references 100, 101 and 102, respectively. Their unitary (one-piece) structure is delimited by a body 100, 101 and 102, respectively.

(12) The devices 100, 101, 102 comprise a reservoir 1, containing the liquid L. Said reservoir 1 has a delivery port 2 (for said liquid L) that is closed off by a removable blow-out disk 3 (for example of the type of a membrane which is frangible in the form of petals or of the type of a spring-loaded valve). The presence of a gaseous headspace above said liquid L should be noted.

(13) The devices 100, 101, 102 comprise a pyrotechnic gas generator, bearing the reference 15 (FIG. 1A), 16 (FIG. 1B) and 17 (FIG. 1C), respectively. The generators depicted are in fact of three types. Each of said generators contains a pyrotechnic charge 7, of the type depicted in FIG. 1 (i.e. inhibited by the varnish 8 on its entire surface, apart from at its end face intended to be initiated in combustion by an ignition system (not shown)).

(14) Located between each of said generators 15, 16 and 17 and the reservoir 1 is the piston 4 (mobile separating member) which is able to slide in a leaktight manner (see the seals 4) under the action of the pressurizing gases generated by the combustion of the charge 7.

(15) In FIG. 1A, the combustion chamber of the generator 15 bears the reference 9a. This combustion chamber 9a corresponds to the expansion chamber 9a for the generated gases. It will be clearly understood that such an arrangement allows implementation within the generator 15 of combustion at constant pressure (in the active phase the volume of liquid delivered corresponding to the volume of generated gas).

(16) In FIG. 1B, the combustion chamber 9b is delimited by a nozzle 10 having a constant throat area. Said nozzle 10 allows fine adjustment of the flow rate of pressurizing gases in the expansion chamber 9a and thus of the pressure exerted on the piston 4 and thus of the delivery flow rate of the liquid (during the active phase).

(17) In FIG. 1C, the combustion chamber 9C is connected to the expansion chamber 9c for the gases by the line 11. It will also be clearly understood that such an arrangement allows the implementation within the generator 17 of combustion at constant pressure (in the active phase the volume of liquid delivered corresponding to the volume of generated gas).

(18) FIG. 2 shows a pyrotechnic charge 70 of type A. This charge, which has a cylindrical shape, of length l, is a monolithic block. It is combustion-inhibited by the varnish 80 at one of its end faces 70c and along only a part (corresponding to a length l2) of its lateral surface 70a, starting from said end face 70c. It is not inhibited at 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; l=l1+l2).

(19) With a charge of this type, the combustion is firstly (during the transitional phase) of the end-burning and side-burning type and is then (during the delivery phase of the liquid) only of the end-burning type (end-burning=cigarette-type combustion). It will thus be understood that said transitional phase (of pressurization of the combustion chamber) is shortened compared with that obtained with a charge such as the one depicted in FIG. 1, inasmuch as, during said transitional phase, the combustion surface is more considerable.

(20) The variation in said combustion surface is shown schematically in FIG. 2.2.

(21) The curves in FIG. 2.1 show the variation in the gas flow rate during the transitional phase (said flow rate decreases as the non-inhibited lateral surface is consumed) and then its constancy during the active phase (cigarette-type combustion along the length l2), the rapid increase in the pressure in the reservoir during said transitional phase and then its constancy during said active phase, and thus the constancy of the liquid flow rate during said active phase (cigarette-type combustion along the length l2).

(22) FIG. 3 shows a charge 700 of type A1.

(23) This charge 700, which has a cylindrical shape, of length l, consists of two juxtaposed cylindrical blocks (portions or parts) 702 and 701. It is inhibited by the varnish 800 at one of its end faces 700c and along its entire lateral surface 700a. It is not inhibited at its other end face 700b which likewise corresponds to the end face 701b of the block 701. The lateral surface 701a of said block 701, which corresponds to a part of the lateral surface 700a of the charge 700 (=701+702), is also inhibited. The combustion of said charge, of its constituent blocks 701 and 702 in succession, is thus cigarette-type combustion, successively during the transitional phase and during the active phase. In order to shorten the duration of said transitional phase, said block 701 has a combustion rate Vc.sub.1(P) greater than the combustion rate Vc.sub.2(P) of the block 702.

(24) FIG. 3.1 shows the constancy of the gas flow rates during the two successive phases (cigarette-type combustions), the flow rate during the transitional phase increasing and then becoming greater than the flow rate during the active phase, as a result of Vc.sub.1>Vc.sub.2. The pressure in the reservoir increases rapidly during said transitional phase. The constancy of said pressure and thus that of the flow rate of liquid delivered is then observed (during the active phase).

(25) FIG. 4 shows a charge 700 of type A2.

(26) The references in FIG. 3 are given again in this figure, followed by a . This is because the elements referenced in FIGS. 3 and 4 correspond to one another. It will already have been understood that the only difference between the charges in FIGS. 3 and 4 (which both have a cylindrical shape) is the lack of combustion-inhibition of the lateral surface 701a of the block 701 at a combustion rate Vc.sub.1, where Vc.sub.1(P)>Vc.sub.2(P). The combustion of the block 701 is thus of the end-burning and side-burning type (just like that of the first part of the charge 70 in FIG. 2). It will be understood that the variations in the gas flow rate, pressure in the reservoir and liquid flow rate, during the combustion of the charge 700 in FIG. 4, are of the type of those shown in FIG. 2.1, with a more rapid rise in pressure in the reservoir. The effects of both the rapid combustion rate Vc.sub.1 and the end-burning and side-burning combustion are combined.