EP0010487B1 - Bridge-wire initiator for propulsive charges - Google Patents

Bridge-wire initiator for propulsive charges Download PDF

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Publication number
EP0010487B1
EP0010487B1 EP79400737A EP79400737A EP0010487B1 EP 0010487 B1 EP0010487 B1 EP 0010487B1 EP 79400737 A EP79400737 A EP 79400737A EP 79400737 A EP79400737 A EP 79400737A EP 0010487 B1 EP0010487 B1 EP 0010487B1
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EP
European Patent Office
Prior art keywords
pyrotechnic
initiator
ignition
housing
composition
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EP79400737A
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German (de)
French (fr)
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EP0010487A1 (en
Inventor
Christian Cannavo
André Espagnacq
Marie Riffault
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Direction General pour lArmement DGA
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Direction General pour lArmement DGA
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    • C—CHEMISTRY; METALLURGY
    • C06—EXPLOSIVES; MATCHES
    • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
    • C06B45/00—Compositions or products which are defined by structure or arrangement of component of product
    • C06B45/04—Compositions or products which are defined by structure or arrangement of component of product comprising solid particles dispersed in solid solution or matrix not used for explosives where the matrix consists essentially of nitrated carbohydrates or a low molecular organic explosive
    • C06B45/06—Compositions or products which are defined by structure or arrangement of component of product comprising solid particles dispersed in solid solution or matrix not used for explosives where the matrix consists essentially of nitrated carbohydrates or a low molecular organic explosive the solid solution or matrix containing an organic component
    • C06B45/10—Compositions or products which are defined by structure or arrangement of component of product comprising solid particles dispersed in solid solution or matrix not used for explosives where the matrix consists essentially of nitrated carbohydrates or a low molecular organic explosive the solid solution or matrix containing an organic component the organic component containing a resin
    • C—CHEMISTRY; METALLURGY
    • C06—EXPLOSIVES; MATCHES
    • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
    • C06B33/00—Compositions containing particulate metal, alloy, boron, silicon, selenium or tellurium with at least one oxygen supplying material which is either a metal oxide or a salt, organic or inorganic, capable of yielding a metal oxide
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
    • F42B3/00—Blasting cartridges, i.e. case and explosive
    • F42B3/10—Initiators therefor
    • F42B3/12—Bridge initiators
    • F42B3/124—Bridge initiators characterised by the configuration or material of the bridge

Definitions

  • the invention relates to devices for the electro-pyrotechnic ignition of propellant charges of artillery and missiles, or of fireworks such as, for example, illuminating, tracing, smoke, incendiary and gas generator devices.
  • Resistant wire systems are igniters in which a filament or pseudofilament is placed within a thermosensitive pyrotechnic substance.
  • a distinction is made between hot wire cells and exploded wire cells.
  • Conductive substance systems are igniters in which the current conducting element consists of the pyrotechnic substance itself; this substance can be conductive by adding various powders.
  • Hot-wire electro-pyrotechnic cells require the use of products sensitive to the heating produced by the passage of a current through the filament.
  • the pyrotechnic charge contained in an electrical igniter of this type is usually ignited using a certain quantity of primary explosive placed around the initiator's initiating wire, either in the form of a compressed powder or in the form of a match head bead.
  • the disadvantages of these igniters are, on the one hand their sensitivity to shocks and friction which gives the components certain risks from the point of view of safety of use, and on the other hand reside in the dangers specific to the handling of the primary explosive.
  • the cells with conductive substances are of simpler design; but their principle of. operation is identical, namely that when the electrical energy expended makes it possible to reach the ignition temperature of the pyrotechnic product based on primary explosive, the igniter operates by emitting a heat and gas flow.
  • Cells with conductive substances therefore offer the same drawbacks as hot-wire cells with, in addition, the fact that the operating energies are difficult to control, which also goes against safety.
  • the pyrotechnic substance In exploded wire cells, the pyrotechnic substance is put into operating mode by the explosion of the filament, a phenomenon which requires a significant supply of electrical energy, much greater than that necessary in the case of ignition of the wire cells. hot. Given the large amount of energy used in this initiation mode, in can use insensitive pyrotechnic mixtures which ignite with difficulty under the action of weak sources of energy, but easily in the case of energies or sufficiently large electric currents. Such compositions are much less sensitive than those used in the previous systems. Consequently, the exploded wire cells are satisfactory from the point of view of safety, but the volume, mass and complexity constraints of the associated electrical source, make the initiation system unusable in many devices.
  • the invention aims to provide a device of the type envisaged to overcome the aforementioned disadvantages.
  • the invention relates to the production of an electro-pyrotechnic igniter operating with a limited electrical energy and not comprising pyrotechnic substances sensitive to external mechanical stresses, to thermal effects and to the electrostatic or electro-magnetic environment.
  • the initiating pyrotechnic composition is preferably composed by the association a zirconium powder, a lead chromate powder and silicone resin, according to the respective mass percentages, 57%, 38% and 5% of RTV 20581 resin sold by Rhone-Poulenc.
  • the pyrotechnic cell is composed by the association of the initiating pyrotechnic composition and the inflammatory pyrotechnic composition according to the respective percentages: 5 to 15% and 85 to 95% and preferably 13% and 87%.
  • the ignition initiator is characterized by the fact that the filament is disposed at the bottom of the housing cavity, its ends being extended by isolated pins, passing through the housing, capable of being connected to a source of electricity.
  • the housing is made of an insulating material, the filament being disposed at the bottom of the housing cavity and being connected to a turn induced by an electromagnetic field integrated in the housing.
  • the housing consists of an inert, or pyrotechnically active, combustible material, for example based on nitrocellulose; the active boxes can undergo sand detonate the initiation using a 30 g hexogen tablet.
  • the initiator comprises a box 1 comprising an open cavity 2 in which is disposed the pyrotechnic cell and the filament 3 heated during ignition.
  • the pins 4 isolated from each other, pass through the bottom of the housing, and are connected to the ends of the filament 3. These pins 4 are intended to be brought into contact with a source of electricity which is not shown.
  • the pyrotechnic cell is constituted by an initiating pyrotechnic composition 5 and by an inflammatory pyrotechnic composition 6.
  • a layer of a few tenths of a millimeter, or approximately 25 to 35 mg, of initiating composition 5 composed by the association of zirconium powder, of powder of lead chromate and silicone resin RTV 20521 playing the role of binder and phlegmatizer is placed in a pasty state on the filament.
  • the respective percentages by mass of zirconium powder, lead chromate powder and RTV 20521 resin are: 57%, 38% and 5%.
  • the ignition temperature of this composition is of the order of 320 ° C. On the other hand, it has an impact sensitivity coefficient (C.S.I.) of 32% starting with 112 joules.
  • This measurement of C.S.I. was determined by method FMD 410 B1 of the manual of operating procedures STPE; the measurement is carried out according to the fall of a determined mass falling from a variable height onto a sample, taken in small quantity in a specially shaped capsule.
  • the coefficient of friction sensitivity (C.S.F.) of this composition is 118 N, a measurement determined as the following, by the FMD 420 A method of the previous manual which implements the Julius Peters device (BAM).
  • BAM Julius Peters device
  • the upper electrode is spherical in shape with a diameter of 10 mm, the lower electrode being cylindrical and with a diameter of 2 mm.
  • An insulating cup has a conical cone-shaped housing in which the pyrotechnic substance to be tested is arranged, without settling.
  • the angle at the top of the truncated cone is 90 °, the diameter of the largest section is 5.5 mm and the lower electrode is flush with the smallest section of diameter 2 mm.
  • This thin layer of pyrotechnic composition playing the role of a match, is suicharged, when dry, with a layer of inflammatory pyrotechnic composition composed by the association of aluminum powder and copper oxide powder , according to the respective percentages by mass of 40% and 60%.
  • This mixture has an ignition temperature of the order of 550 ° C, a C.S.I. 112 joules, a C.S.F. of 335 N, a coefficient of sensitivity to static electricity of around 50 millijoules (1000 pF capacitor charged - at 10 kV).
  • inflammatory pyrotechnic composition compressed to 300 bar was used, which gives the initiator an inflammatory power largely sufficient to light effectively black powder type PN L 1, placed a few millimeters in a sachet in airy fabric.
  • the opening of the cavity 2 of the housing is closed by a disk 7 of strong paper, glued and varnished, so as to isolate the pyrotechnic cell from the outside environment.
  • FIG. 2 Another embodiment (fig. 2) is an initiator, the firing order of which is effected by induction of a high frequency high power signal; which offers the advantage, compared to conventional electric initiators, of not requiring any direct connection to the filament circuit: this feature makes it possible to keep intact the intrinsic characteristics of the initiator from the point of view of electrical safety because the direct addition of conductors can, by causing an antenna effect, capture electrostatic or electromagnetic energies and make the system aware of these risks.
  • This particular embodiment is composed of a housing 8 made of inert or active insulating material.
  • This housing has a cavity 9 in which is disposed a disc 10 (fig. 2 and 3) on which is maintained an induced turn 11 whose ends 12 extend to the vicinity of the center of the disc, and on which a filament is welded 13.
  • This disc 10 is held at the bottom of the cavity 9 of the housing 8 by a cover 14 made of the same material as the housing 8.
  • This cover 14 is fitted onto the lateral surface of the cavity 9 and can, for example, be there be secured by bonding.
  • this cover has a hole 15 opening on the filament 13. This hole 15, in the same way as in the embodiment described above, is filled by the pyrotechnic cell, and is closed by a paper disc. strong 16.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Metallurgy (AREA)
  • Health & Medical Sciences (AREA)
  • Materials Engineering (AREA)
  • Dispersion Chemistry (AREA)
  • Molecular Biology (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Engineering & Computer Science (AREA)
  • Air Bags (AREA)
  • Resistance Heating (AREA)

Description

L'invention se rapporte aux dispositifs d'allumage électro-pyrotechnique de charges propulsives d'artillerie et de missiles, ou d'artifices tels que par exemple des engins éclairants, traçants, fumigènes, incendiaires et générateurs de gaz.The invention relates to devices for the electro-pyrotechnic ignition of propellant charges of artillery and missiles, or of fireworks such as, for example, illuminating, tracing, smoke, incendiary and gas generator devices.

Il existe actuellement deux sortes d'inflammateurs électriques: les systèmes à fil résistant et les systèmes à substance conductrice.There are currently two types of electrical igniters: resistance wire systems and conductive substance systems.

Les systèmes à fil résistant sont des inflammateurs dans lesquels un filament ou pseudo- filament est disposé au sein d'une substance pyrotechnique thermo-sensible. Parmi les systèmes à fil résistant on distingue les cellules à fil chaud est les cellules à fil explosé.Resistant wire systems are igniters in which a filament or pseudofilament is placed within a thermosensitive pyrotechnic substance. Among the resistant wire systems a distinction is made between hot wire cells and exploded wire cells.

Les systèmes à substance conductrice sont des inflammateurs dans lesquels l'élément conducteur de courant est constitué par la substance pyrotechnique elle-même; cette substance peut être conductrice par addition de poudres diverses.Conductive substance systems are igniters in which the current conducting element consists of the pyrotechnic substance itself; this substance can be conductive by adding various powders.

Les cellules électro-pyrotechniques à fil chaud nécessitent l'emploi de produits sensibles à l'échauffement produit par le passage d'un courant dans le filament. La charge pyrotechnique contenue dans un inflammateur électrique de ce type est habituellement allumée à l'aide d'une certaine quantité d'explosif primaire disposée autour du fil d'amorçage de l'initiateur, soit sous la forme d'une poudre comprimée, soit sous la forme d'une perle de tête d'allumette. Les Inconvénients de ces inflammateurs sont, d'une part leur sensibilité aux chocs et à la friction qui confère aux composants certains risques du point de vue de la sécurité d'utilisation, et d'autre part résident dans les dangers propres à la manipulation de l'explosif primaire.Hot-wire electro-pyrotechnic cells require the use of products sensitive to the heating produced by the passage of a current through the filament. The pyrotechnic charge contained in an electrical igniter of this type is usually ignited using a certain quantity of primary explosive placed around the initiator's initiating wire, either in the form of a compressed powder or in the form of a match head bead. The disadvantages of these igniters are, on the one hand their sensitivity to shocks and friction which gives the components certain risks from the point of view of safety of use, and on the other hand reside in the dangers specific to the handling of the primary explosive.

Les cellules à substances conductrices sont de conception plus simple; mais leur principe de. fonctionnement est identique, à savoir que lorsque l'énergie électrique dépensée permet d'atteindre la température d'inflammation du produit pyrotechnique à base d'explosif primaire, l'inflammateur fonctionne en émettant un flux thermique et gazeux. Les cellules à substances conductrices offrent donc les mêmes inconvénients que les cellules à fil chaud avec, en plus, le fait que les énergies de fonctionnement sont difficilement maîtrisables ce qui va sussi à l'encontre de la sécurité.The cells with conductive substances are of simpler design; but their principle of. operation is identical, namely that when the electrical energy expended makes it possible to reach the ignition temperature of the pyrotechnic product based on primary explosive, the igniter operates by emitting a heat and gas flow. Cells with conductive substances therefore offer the same drawbacks as hot-wire cells with, in addition, the fact that the operating energies are difficult to control, which also goes against safety.

Dans les cellules à fil explosé, la substance pyrotechnique est mise en régime de fonctionnement par l'explosion du filament, phénomène qui demande un apport d'énergie électrique important, très supérieur à celui nécessaire dans le cas de l'allumage des cellules à fil chaud. Compte tenu de la grande quantité d'énergie utilisée dans ce mode d'initiation, in peut employer des mélanges pyrotechniques peu sensibles s'enflammant difficilement sous l'action de faibles sources d'énergie, mais aisément dans le cas d'énergies ou de courants électriques suffisamment grands. De telles compositions sont nettement moins sensibles que celles utilisées dans les systèmes précédents. En conséquence, les cellules à fil explosé sont satisfaisantes du point de vue de la sécurité, mais les contraintes en volume, en masse et en complexité de la source électrique associée, rendent le système d'initiation inutilisable dans nombre de dispositifs.In exploded wire cells, the pyrotechnic substance is put into operating mode by the explosion of the filament, a phenomenon which requires a significant supply of electrical energy, much greater than that necessary in the case of ignition of the wire cells. hot. Given the large amount of energy used in this initiation mode, in can use insensitive pyrotechnic mixtures which ignite with difficulty under the action of weak sources of energy, but easily in the case of energies or sufficiently large electric currents. Such compositions are much less sensitive than those used in the previous systems. Consequently, the exploded wire cells are satisfactory from the point of view of safety, but the volume, mass and complexity constraints of the associated electrical source, make the initiation system unusable in many devices.

L'invention a pour but de fournir un dispositif du type envisagé permettant de pallier les désavantages précités.The invention aims to provide a device of the type envisaged to overcome the aforementioned disadvantages.

L'invention concerne la réalisation d'une inflammateur électro-pyrotechnique fonctionnant avec une énergie électrique limitée et ne comportant pas de substances pyrotechniques sensibles aux sollicitations mécaniques extérieures, aux effets thermiques et à l'environnement électrostatique ou électro-magnétique.The invention relates to the production of an electro-pyrotechnic igniter operating with a limited electrical energy and not comprising pyrotechnic substances sensitive to external mechanical stresses, to thermal effects and to the electrostatic or electro-magnetic environment.

L'invention a pour objet un initiateur d'allumage à fil chaud comprenant:

  • - un boîtier comportant une cavité ouverte,
  • - un filament disposé dans cette cavité,
  • - une cellule pyrotechnique composée: = d'une composition pyrotechnique initiatrice, disposée en contact intime avec le filament, dont le coefficient de sensibilité à l'impact est au moins égal à 100 joules, le coefficient de sensibilité à la friction est d'au moins 100 N, le coefficient de sensibilité à l'électricité- statique est d'environ 16 millijoules, et la température d'inflammation est comprise entre 250 et 350°C, ladite composition initiatrice étant composée par l'association d'une poudre de zirconium, d'une poudre de chromate de plomb et de résine silicone, selon les pourcentages respectifs en masse: 40 à 80%, 18 à 60% et 2 à 8%,
    • = d'une composition pyrotechnique inflammatrice, disposée au voisinage ou au contact de la composition initiatrice, cette composition inflammatrice ayant: un coefficient de sensibilité à l'impact d'au moins 100 joules, un coefficient de sensibilité à la friction d'au moins 300 N, un coefficient de sensibilité à l'électricité statique d'environ 50 millijoules, et une température d'inflammation comprise 400 et 750°C, ladite composition infiam- matrice étant composée par l'association d'une poudre d'aluminium, d'une poudre d'oxyde de cuivre et éventuellement d'un polymère nitré selon les pourcentages respectifs en masse: 15 à 60%, 40 à 85%, et 0 à 12%.
The subject of the invention is a hot wire ignition initiator comprising:
  • - a housing comprising an open cavity,
  • - a filament placed in this cavity,
  • - a pyrotechnic cell composed: = of an initiating pyrotechnic composition, placed in intimate contact with the filament, whose coefficient of sensitivity to impact is at least equal to 100 joules, the coefficient of sensitivity to friction is at least minus 100 N, the coefficient of sensitivity to static electricity is approximately 16 millijoules, and the ignition temperature is between 250 and 350 ° C, said initiating composition being composed by the association of a powder of zirconium, of a lead chromate powder and of silicone resin, according to the respective percentages by mass: 40 to 80%, 18 to 60% and 2 to 8%,
    • = of an inflammatory pyrotechnic composition, placed in the vicinity or in contact with the initiating composition, this inflammatory composition having: a coefficient of sensitivity to impact of at least 100 joules, a coefficient of sensitivity to friction of at least 300 N, a coefficient of sensitivity to static electricity of around 50 millijoules, and an ignition temperature between 400 and 750 ° C, said infiamatrix composition being composed by the association of an aluminum powder, of a copper oxide powder and optionally of a nitrated polymer according to the respective percentages by mass: 15 to 60%, 40 to 85%, and 0 to 12%.

La composition pyrotechnique initiatrice est composée préférentiellement par l'association d'une poudre de zirconium, d'une poudre de chromate de plomb et de résine silicone, selon les pourcentages en masse respectifs, 57%, 38% et 5% de résine RTV 20581 commercialisée par la société Rhone-Poulenc.The initiating pyrotechnic composition is preferably composed by the association a zirconium powder, a lead chromate powder and silicone resin, according to the respective mass percentages, 57%, 38% and 5% of RTV 20581 resin sold by Rhone-Poulenc.

La cellule pyrotechnique est composée par l'association de la compositon pyrotechnique initiatrice et de la composition pyrotechnique inflammatrice selon les pourcentages respectifs: 5 à 15% et 85 à 95% et préférentiellement 13% et 87%.The pyrotechnic cell is composed by the association of the initiating pyrotechnic composition and the inflammatory pyrotechnic composition according to the respective percentages: 5 to 15% and 85 to 95% and preferably 13% and 87%.

L'initiatuer d'allumage est caractérisé par le fait que le filament est disposé au fond de la cavité du boîtier, ses extrémités se prolongeant par des broches isolées, traversant le boîter, susceptibles d'être connectées à une source d'électricité.The ignition initiator is characterized by the fact that the filament is disposed at the bottom of the housing cavity, its ends being extended by isolated pins, passing through the housing, capable of being connected to a source of electricity.

Une autre caractéristique de l'invention réside dans le fait que le boîtier est constitué par un matériau isolant, le filament étant disposé au fonde de la cavité du boîtier et étant connecté à une spire induite par un champ électromagnétique intégrée au boîtier.Another characteristic of the invention lies in the fact that the housing is made of an insulating material, the filament being disposed at the bottom of the housing cavity and being connected to a turn induced by an electromagnetic field integrated in the housing.

Selon un autre mode de réalisation le boîtier est constitué d'un matériau combustible inerte, ou pyrotechniquement actif, par exemple à base de nitrocellulose; les boîtiers actifs pouvant subir sand détoner l'amorçage à l'aide d'un comprimé de 30 g d'hexogène.According to another embodiment, the housing consists of an inert, or pyrotechnically active, combustible material, for example based on nitrocellulose; the active boxes can undergo sand detonate the initiation using a 30 g hexogen tablet.

Pour mieux comprendre l'objet de l'invention on va décrire à titre indicatif et non limitatif deux modes de réalisation représentés sur les dessins annexés. Sur les dessins:

  • - la figure 1 représente un initiateur selon l'invention dont le filament est connecté directement à une source d'electricité,
  • - la figure 2 représente un initiateur à fil chaud fonctionnant par induction électro-' magnétique,
  • - la figure 3 représente la spire induite et le fil disposés dans l'initiateur représenté à la figure 2.
To better understand the object of the invention, two embodiments shown in the accompanying drawings will be described by way of non-limiting indication. In the drawings:
  • FIG. 1 represents an initiator according to the invention, the filament of which is connected directly to a source of electricity,
  • FIG. 2 represents a hot wire initiator operating by electromagnetic induction,
  • FIG. 3 represents the induced turn and the wire arranged in the initiator shown in FIG. 2.

Suivant un mode de réalisation (fig. 1) l'initiateur comprend un boîtier 1 comportant une cavité ouverte 2 dans laquelle est disposée la cellule pyrotechnique et le filament 3 chauffé lors de la mise à feu. Les broches 4, isolées entre elles, traversent le fond du boîtier, et sont connectées aux extrémités du filament 3. Ces broches 4 sont destinées à être mises au contact d'une source d'electricité non représentée. La cellule pyrotechnique est constituée par une composition pyrotechnique initiatrice 5 et par une composition pyrotechnique inflammatrice 6. Une couche de quelques diximèmes de millimètre, soit environ 25 à 35 mg, de compositon initiatrice 5 composée par l'association de poudre de zirconium, de poudre de chromate de plomb et de résine silicone RTV 20521 jouant le rôle de liant et de flegmatisant est disposée à l'état pâteux sur le filament. Les pourcentages respectifs en masse de poudre de zirconium, de poudre de chromate de plomb et de résine RTV 20521 sone de: 57%, 38% et 5%. La température d'inflammation de cette composition est de l'ordre de 320°C. D'autre part, elle présente un coefficient de sensibilité à l'impact (C.S.I.) de 32% de départ sous 112 joules. Cette mesure de C.S.I., comme les suivantes ont été déterminées par la méthode FMD 410 B1 du manuel des modes opératoires STPE; la mesure s'effectue d'après la chute d'une masse déterminée tombant d'une hauteur variable sur un échantillon, pris en faible quantité dans une capsule de forme spéciale. Le coefficient de sensibilité à la friction (C.S.F.) de cette composition est de 118 N, mesure déterminée comme les suivantes, par la méthode FMD 420 A du manuel précédent qui met en oeuvre l'appareil Julius Peters (BAM). D'autre part, une énergie inférieure à environ 16 millijoules (décharge d'un condensateur de 100 picofarads chargé sous 18 kilovolts), n'est pas suffisante pour provoquer l'allumage de la substance par étincelle. Cette dernière mesure comme les suivantes a été effectuée en disposant la substance pyrotechnique entre deux électrodes connectées à une batterie de condensateurs. L'électrode supérieure est de forme sphérique de diamètre 10 mm, l'électrode inférieure étant cylindrique et de diamètre 2 mm. Un godet isolant comporte un logement tron conique dans lequel est disposé, sans tassement, la substance pyrotechnique à tester. L'angle au sommet du tronc de cône est de 90°, le diamètre de la plus grande section est de 5,5 mm et l'électrode inférieure affleure la plus petite section de diamètre 2 mm.According to one embodiment (fig. 1) the initiator comprises a box 1 comprising an open cavity 2 in which is disposed the pyrotechnic cell and the filament 3 heated during ignition. The pins 4, isolated from each other, pass through the bottom of the housing, and are connected to the ends of the filament 3. These pins 4 are intended to be brought into contact with a source of electricity which is not shown. The pyrotechnic cell is constituted by an initiating pyrotechnic composition 5 and by an inflammatory pyrotechnic composition 6. A layer of a few tenths of a millimeter, or approximately 25 to 35 mg, of initiating composition 5 composed by the association of zirconium powder, of powder of lead chromate and silicone resin RTV 20521 playing the role of binder and phlegmatizer is placed in a pasty state on the filament. The respective percentages by mass of zirconium powder, lead chromate powder and RTV 20521 resin are: 57%, 38% and 5%. The ignition temperature of this composition is of the order of 320 ° C. On the other hand, it has an impact sensitivity coefficient (C.S.I.) of 32% starting with 112 joules. This measurement of C.S.I., like the following ones, was determined by method FMD 410 B1 of the manual of operating procedures STPE; the measurement is carried out according to the fall of a determined mass falling from a variable height onto a sample, taken in small quantity in a specially shaped capsule. The coefficient of friction sensitivity (C.S.F.) of this composition is 118 N, a measurement determined as the following, by the FMD 420 A method of the previous manual which implements the Julius Peters device (BAM). On the other hand, an energy lower than approximately 16 millijoules (discharge of a capacitor of 100 picofarads charged under 18 kilovolts), is not sufficient to cause the ignition of the substance by spark. This last measurement, like the following, was carried out by placing the pyrotechnic substance between two electrodes connected to a battery of capacitors. The upper electrode is spherical in shape with a diameter of 10 mm, the lower electrode being cylindrical and with a diameter of 2 mm. An insulating cup has a conical cone-shaped housing in which the pyrotechnic substance to be tested is arranged, without settling. The angle at the top of the truncated cone is 90 °, the diameter of the largest section is 5.5 mm and the lower electrode is flush with the smallest section of diameter 2 mm.

Cette mince couche de composition pyrotechnique, jouant le rôle d'allumette, est suichargée, lorsqu'elle, est sèche, d'une couche de composition pyrotechnique inflammatrice composée par l'association de poudre d'aluminium et de poudre d'oxyde de cuivre, selon les pourcentages respectifs en masse de 40% et 60%. Ce mélange présente une température d'inflammation de l'ordre de 550°C, un C.S.I. de 112 joules, un C.S.F. de 335 N, un coefficient de sensibilité à l'électricité statique d'environ 50 millijoules (condensateur de 1000 pF chargé- sous 10 kV). Dans cet exemple on a utilisé envirorn 200 mg de composition pyrotechnique inflammatrice comprimée à 300 bars, ce qui donne à l'initiateur un pouvoir inflammatoire largement suffisant pour allumer efficacement de la poudre noire type PN L 1, placée à quelques millimètres dans un sachet en tissu aéré. L'ouverture de la cavité 2 du boîtier est obturée par un disque 7 de papier fort, collé et vernis, de façon à isoler la cellule pyrotechnique du milieu extérieur.This thin layer of pyrotechnic composition, playing the role of a match, is suicharged, when dry, with a layer of inflammatory pyrotechnic composition composed by the association of aluminum powder and copper oxide powder , according to the respective percentages by mass of 40% and 60%. This mixture has an ignition temperature of the order of 550 ° C, a C.S.I. 112 joules, a C.S.F. of 335 N, a coefficient of sensitivity to static electricity of around 50 millijoules (1000 pF capacitor charged - at 10 kV). In this example, 200 mg of inflammatory pyrotechnic composition compressed to 300 bar was used, which gives the initiator an inflammatory power largely sufficient to light effectively black powder type PN L 1, placed a few millimeters in a sachet in airy fabric. The opening of the cavity 2 of the housing is closed by a disk 7 of strong paper, glued and varnished, so as to isolate the pyrotechnic cell from the outside environment.

Un autre mode de réalisation (fig. 2) est un initiateur dont l'ordre de mise à feu s'effectue par induction d'un signal haute fréquence de forte puissance; ce qui offre l'avantage, par rapport aux initiateurs électriques classiques, de ne nécessiter aucune connexion directe sur le circuit du filament: cette particularité permet de conserver intactes les caractéristiques intrinsèques de l'initiateur au point de vue de la sécurité électrique car l'adjonction directe de conducteurs peut, en provoquant un effet d'antenne, capter des énergies électrostatiques ou électromagnétiques et sensibiliser le système vis à vis de ces risques.Another embodiment (fig. 2) is an initiator, the firing order of which is effected by induction of a high frequency high power signal; which offers the advantage, compared to conventional electric initiators, of not requiring any direct connection to the filament circuit: this feature makes it possible to keep intact the intrinsic characteristics of the initiator from the point of view of electrical safety because the direct addition of conductors can, by causing an antenna effect, capture electrostatic or electromagnetic energies and make the system aware of these risks.

Cette réalisation particulière est composée d'un boîtier 8 en matériau isolant inerte ou actif. Ce boîtier comporte une cavitié 9 dans laquelle est disposé un disque 10 (fig. 2 et 3) sur lequel est maintenue une spire induite 11 dont les extrémités 12 se prolongent jusqu'au voisinage du centre du disque, et sur lesquelles est soudé un filament 13. Ce disque 10 est maintenu au fond de la cavité 9 du boîtier 8 par un couvercle 14 réalisé dans le même matériau que le boîtier 8. Ce couvercle 14 est emboite sur la surface latérale de la cavité 9 et peut, par exemple, y être assujetti par collage. D'autre part, ce couvercle comporte un percement 15 de- bouchant sur la filament 13. Ce percement 15, de la même façon que dans la réalisation décrite précédemment, est rempli par la cellule pyrotechnique, et, est obturé par un disque de papier fort 16.This particular embodiment is composed of a housing 8 made of inert or active insulating material. This housing has a cavity 9 in which is disposed a disc 10 (fig. 2 and 3) on which is maintained an induced turn 11 whose ends 12 extend to the vicinity of the center of the disc, and on which a filament is welded 13. This disc 10 is held at the bottom of the cavity 9 of the housing 8 by a cover 14 made of the same material as the housing 8. This cover 14 is fitted onto the lateral surface of the cavity 9 and can, for example, be there be secured by bonding. On the other hand, this cover has a hole 15 opening on the filament 13. This hole 15, in the same way as in the embodiment described above, is filled by the pyrotechnic cell, and is closed by a paper disc. strong 16.

Claims (9)

1. Hotwire ignition initiator characterized by the fact that it consists of:
- a housing (1) having an open cavity (2)
- filament (3) arranged in said cavity
- a pyrotechnic cell composed:
of an initiator pyrotechnic composition (5) arranged in intimate contact with the filament (3), the coefficient of sensitivity to impact of which is at least equal to 100 joules, the coefficient of sensitivity to friction of which is at least 100 N, the coefficient of sensitivity to static electricity of which is about (16) millijoules and the ignition temperature of which is between 250 and 350°C, said initiator pyrotechnic composition is formed by the combination of a zirconium power, a lead-chromate powder and silicone resin in accordance with the weight precent-- ages of 40 to 80%, 18 to 60%, and 2 to 8% respectively,
- of an igniter pyrotechnic composition (6) arranged in the vicinity of or in contact with the initiator composition said igniter composition having a coefficient of sensitivity to impact of at least 100 joules, a coefficient of sensitivity to friction of at least 300 N, a coefficient of sensitivity to static electricity of about 50 millijoules and an ignition temperature of between 400 and 750°C, said igniter pyrotechnic composition is formed by the combination of an aluminum powder, a copper oxide powder and possibly a nitro- polymer in accordance with the weight percentages of 15 to 60%, 40 to 85% and 0 to 12% respectively:
2. An ignition initiator according to Claim 1, characterized by the fact that the initiator pyrotechnic composition (5) is formed by the combination of a zirconium powder, a lead-chromate powder and silicone resin RTV 20581 in the weight percentages of 57%, 38% and 5% respectively.
3. An ignition initiator according to Claim 1, characterized by the fact that the ignition composition (6) is formed by the combination of an aluminum powder and a copperoxide powder in the weight percentages of 40% and 60% respectively.
4. An ignition initiator according to any of the preceding claims, characterized by the fact that the pyrotechnic cell is formed by the combination of the initiator pyrotechnic composition (5) and the igniter pyrotechnic composition (6) in the percentages of 5 to 15% and 85 to 95% respectively.
5. An ignition initiator according to Claim 4, characterized by the fact that the pyrotechnic cell is formed by the combination of the initiator pyrotechnic composition (5) and the igniter pyrotechnic composition (6) in the percentages of 13% and 87% respectively.
6. An ignition initiator according to any of the preceding claims, characterized by the fact that the filament is arranged at the bottom of the cavity of the housing (1), its ends extending through insulated pins passing through the housing, which can be connected to a source of electricity.
7. An ignition initiator according to any of Claims 1 to 5, characterized by the fact that the housing (8) is formed of an insulating material, the filament (3) being arranged at the bottom of the cavity of the housing and being connected to a coil turn induced by an electromagnetic field which is integrated in the housing.
8. An ignition initiator according to any of the preceding claims, characterized by the fact that the housing is formed of a combustible material.
9. An ignition initiator according to Claim 7, characterized by the fact that the induced coil (11) turn is arranged between the housing (8) and a cover (14) which contains the pyrotechnic cell.
EP79400737A 1978-10-13 1979-10-12 Bridge-wire initiator for propulsive charges Expired EP0010487B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7829210 1978-10-13
FR7829210A FR2438821A1 (en) 1978-10-13 1978-10-13 SAFETY HOT WIRE IGNITION DEVICE

Publications (2)

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EP0010487A1 EP0010487A1 (en) 1980-04-30
EP0010487B1 true EP0010487B1 (en) 1982-06-23

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US (1) US4354432A (en)
EP (1) EP0010487B1 (en)
BE (1) BE879385A (en)
CH (1) CH634143A5 (en)
DE (1) DE2963180D1 (en)
FR (1) FR2438821A1 (en)
IT (1) IT1123852B (en)

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Also Published As

Publication number Publication date
CH634143A5 (en) 1983-01-14
FR2438821A1 (en) 1980-05-09
IT1123852B (en) 1986-04-30
DE2963180D1 (en) 1982-08-12
FR2438821B1 (en) 1981-03-27
IT7926509A0 (en) 1979-10-15
US4354432A (en) 1982-10-19
BE879385A (en) 1980-02-01
EP0010487A1 (en) 1980-04-30

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