EP0592292B1 - Elektrischer Zünder mit leitender Zusammensetzung - Google Patents

Elektrischer Zünder mit leitender Zusammensetzung Download PDF

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Publication number
EP0592292B1
EP0592292B1 EP93402426A EP93402426A EP0592292B1 EP 0592292 B1 EP0592292 B1 EP 0592292B1 EP 93402426 A EP93402426 A EP 93402426A EP 93402426 A EP93402426 A EP 93402426A EP 0592292 B1 EP0592292 B1 EP 0592292B1
Authority
EP
European Patent Office
Prior art keywords
conductive
primer
resistance
resistive element
pyrotechnic composition
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP93402426A
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English (en)
French (fr)
Other versions
EP0592292A1 (de
Inventor
Guy Lagofun
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Giat Industries SA
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Giat Industries SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Giat Industries SA filed Critical Giat Industries SA
Publication of EP0592292A1 publication Critical patent/EP0592292A1/de
Application granted granted Critical
Publication of EP0592292B1 publication Critical patent/EP0592292B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42C—AMMUNITION FUZES; ARMING OR SAFETY MEANS THEREFOR
    • F42C19/00—Details of fuzes
    • F42C19/08—Primers; Detonators
    • F42C19/12—Primers; Detonators electric
    • 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
    • F42B3/18—Safety initiators resistant to premature firing by static electricity or stray currents
    • F42B3/182—Safety initiators resistant to premature firing by static electricity or stray currents having shunting means

Definitions

  • the field of the present invention is that of electrical primers comprising a conductive pyrotechnic composition.
  • WO90 / 14572 describes an electrical primer with conductive composition more particularly intended for automotive safety applications.
  • a layer of carbon is deposited between the electrodes in order to improve the behavior of the primer with respect to electromagnetic radiation and electrostatic discharges.
  • the carbon layer isolates the conductive composition from the central contact pad and therefore has the effect of directly initiating the composition by heating.
  • Such a primer is of the type with a resistive heating element, it therefore does not have the simplicity of implementation of the primers with conductive composition in which it is the pyrotechnic composition itself which constitutes the heating element.
  • this primer comprises a conductive pyrotechnic composition of the metal / oxidizing type and which is therefore devoid of primary explosive.
  • the conductive composition proposed by this patent is less sensitive than a pyrotechnic composition based on primary explosive. It therefore has a much longer operating time, which makes it unusable in military applications, in particular in priming ammunition at high rates of fire.
  • Patent FR-A-2 436 963 which describes the preamble of claim 1, proposes to have a resistive element connected to the electrodes of the primer, in parallel with the conductive composition.
  • This resistor has the function of stabilizing the value of the equivalent resistance of the primer, which ensures an energy sharing between the resistor and the composition and makes it possible to obtain an improved operating consistency and desensitizes the primer at the level of the missed threshold.
  • Such an arrangement makes it possible to increase the reliability of the primers with conductive composition by limiting the dispersion of the values of the electrical resistances of the primers of the same manufacturing batch.
  • This patent recommends the use of a resistive element whose resistance is between 0.8 and 2 times that of the pyrotechnic composition. This gives a value of the equivalent resistance of the primer which is close to that of the resistance of the pyrotechnic composition but which is much more stable.
  • the conductive pyrotechnic composition used is generally a primary explosive (such as lead azide, lead trinitroresorcinate or tetrazene) mixed with particles of a conductive material such as graphite. .
  • the primer according to the invention can withstand the main existing safety tests such as the electrostatic safety test according to the MIL STD 1512 standard (method 205) (which provides for a discharge of 25 kilo Volts on a primer connected in series with a resistance 5000 ohms) or the heating test according to the MIL STD 1512 standard (method 202) (which provides for applying for 5 minutes a current delivering 1 Ampere under 1 Watt minimum or a power of 1 Watt with a current of 1 ampere minimum).
  • This primer nevertheless remains simple in design, therefore easy to produce in series and at a lower cost, and it has a much higher operating reliability than that of primers with conductive composition according to the state of the art.
  • the invention makes it possible to obtain excellent reproducibility of the operating times.
  • the subject of the invention is an electrical primer comprising a conductive initiating pyrotechnic composition placed in contact with a useful pyrotechnic charge and two electrodes in electrical contact with the conductive pyrotechnic composition, primer also comprising a resistive element connected in parallel with the conductive pyrotechnic composition, characterized in that the electrical resistance of the resistive element has a non-zero value of less than 0.8 times that of the static electrical resistance of the conductive pyrotechnic composition contained in the primer and said electrical resistance being equal or less than 20 Ohms.
  • the resistive element will have an electrical resistance between 0.5 ohms and 10 ohms, and preferably an electrical resistance of the order of 2 ohms.
  • one of the electrodes is in contact with an external envelope of the primer and the other electrode is constituted by a metallic body coaxial with the envelope, and the resistive element consists of a pinched conductive cup. between the metal body and the envelope.
  • the metal body may have a flat surface on which an insulating washer is arranged and the second electrode may consist of a metal washer in contact with the insulating washer. A cylindrical cavity created by the two washers is then filled with the conductive pyrotechnic composition.
  • the bucket can be made of plastic material loaded with conductive powder, for example thermoplastic material loaded with 3 to 10% graphite powder.
  • the conductive pyrotechnic composition will preferably contain at least one primary explosive.
  • One of the advantages of the invention is therefore to make it possible, with respect to electromagnetic radiation and electrostatic discharges, to initiate initiating components comprising primary explosives, therefore components which are in principle extremely sensitive to such environmental constraints. .
  • a primer 1 according to the invention comprises a substantially cylindrical metal casing 2 which contains a useful pyrotechnic charge 3 and a conductive pyrotechnic composition 4.
  • the payload 3 is an ignition composition of known type, for example a mixture of lead trinitroresorcinate, potassium chlorate, barium nitrate, calcium silicide and graphite in the respective mass proportions of 48%, 28%, 12%, 10% and 2%.
  • This payload 3 is contained in a metal cell 11, the bottom of which is provided with a central opening 14.
  • a metal flake 12 closes the cell 11.
  • the conductive composition 4 is placed in contact with two electrodes 5 and 9.
  • the electrode 5 is constituted by a metal body coaxial with the envelope 2 and having a flat surface 10 in contact with the conductive composition 4.
  • the electrode 9 is a metal washer placed under the metal cell 11 and parallel to the flat surface 10. It is in electrical contact with the casing 2 via the cell 11.
  • a washer 8 made of electrically insulating material separates the metal washer 9 from the body 5.
  • the washer 8 will for example be made of epoxy resin or glass. Its dimensions are substantially identical to that of the metal washer 9.
  • the two washers 8 and 9 define a cylindrical cavity which is filled with the conductive composition 4.
  • the latter consists of an explosive of the primary type (or a mixture comprising one or more of these explosives) added with a particulate conductive material such as graphite.
  • the primary explosive may be chosen from the following compounds: mercury fulminate, lead trinitroresorcinate, lead azide or tetrazene.
  • a cup 6 of conductive material is pinched between the metal body 5 and the casing 2.
  • This cup 6 is therefore both in contact with an internal cylindrical surface 7 of the casing 2 and with the external surface of the metal body 5.
  • the cup 6 is also in contact with the external cylindrical surfaces of the washers 8 and 9.
  • the cup 6 constitutes a resistive element connected to the electrodes 5 and 9 and in parallel with the resistance formed by the conductive pyrotechnic composition 4.
  • the resistance of this cup will be different from zero and less than 0.8 times the inherent resistance of the conductive composition 4.
  • the bucket could be made of a material of the thermoplastic type, for example polyethylene terephthalate loaded with graphite.
  • thermosetting plastic loaded with graphite directly into the shell of the primer.
  • the bucket can finally be made of ceramic on which deposits of conductive or semiconductor materials will be produced, carrying out electrical bridging between the metal body 5 and the casing 2.
  • the proportion by mass of graphite will preferably be chosen between 3 and 10% of the total mass of the bucket.
  • compositions used in the primers with conductive composition have a resistivity such that the static resistance of the composition contained in the primer is between 30 and 300 ohms. These values ensure in principle a certain non-operation for voltages from 6 to 10 volts.
  • the preferred value for the resistance of the bucket will be the lowest compatible with the electrical supply of the firing generator of the weapon, ie practically a resistance comprised between 1 and 2.5 ohms.
  • the electrical energy supplied by a generator is divided between the two resistors, the lowest resistance absorbing the maximum of energy.
  • the conductive composition absorbs the quantity of energy which it needs to be initiated, regardless of the value of the weak resistance which is mounted in parallel. Quite constant operating times are thus obtained for resistance values placed in parallel which vary from 2 to 20 ohms.
  • the resistive element of low resistance which is mounted in parallel therefore does not affect operation. However, it makes it more resistant, both to electrostatic discharges and to overheating by the Joule effect.
  • the resistive element also makes it possible to limit the dispersions of the values of the resistances to a level substantially equivalent to that of a filament primer.
  • Table 1 gives the values of equivalent resistances (Rr in Ohms), measured with a measurement current between 0.5 and 1 milliamps. These equivalent resistance values are given as a function of the values of the resistors connected in parallel (Rs in Ohms). The table also gives the standard deviations, the manipulations being carried out in each case with batches of 20 primers. The last column of the table gives for memory the values measured for a primer with conductive composition devoid of resistance mounted in parallel. Table 1. Rs ( ⁇ ) 1 2 5 8 10 15 20 Absent Rr ( ⁇ ) 0.98 1.92 4.67 7.05 8.58 12.21 15.83 65 to 85 3 ⁇ / Rr (%) 1.5 2.3 1.9 5.4 5.9 11.5 11.1 50 to 90
  • Table 2 gives, as a function of the values of the resistors connected in parallel (Rs in Ohms), the values of the operating times Tt (in microseconds), that is to say the times separating the electrical supply from the initiation primer (judged by the appearance of the first glow at the exit of the component). It also gives the associated standard deviations for lots of 20 primers for each manipulation as well as the number of initiation misfires.
  • the power supply at 27 Volts is provided by a firing capacity of 23 micro Farad.
  • this operation is certain for relatively low values of the resistance connected in parallel and for a relatively low ignition voltage (27 volts).
  • the first column corresponds to a primer according to the state of the art (without resistive element mounted in parallel).
  • Table 4 Rs ( ⁇ ) absent 20 15 10 8 5 2 1 25 kV 20/20 9/20 8/20 3/20 2/20 0/20 0/20 0/20 20 kV 20/20 7/20 1/20 1/20 0/20 15 kV 19/20 2/20 0/20 0/20 10 kV 10/20 0/20
  • the cup 6 has a large contact surface both with the metal body 5 and with the casing 2, which has the effect of reducing the electrical resistance between these two elements.
  • the metal cell 11 is positioned.
  • An annular crimp 13 is made to immobilize the stack of the cell 11, the washers 8 and 9, the metal body 5 and the cup 6 relative to the casing 2.
  • the metallic body is thus held firmly in abutment against the bucket, which ensures the reproducibility of the electrical resistance of the latter.
  • the conductive composition 4 is placed in the cylindrical space delimited by the washers and the bottom of the cell 11.
  • the payload 3 is placed in the cell 11 and then covered with the paillet 12.
  • the paillet and the charge 3 are compressed, which brings the latter into contact with the conductive composition 4.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Air Bags (AREA)
  • Conductive Materials (AREA)
  • Paints Or Removers (AREA)
  • Fuses (AREA)

Claims (9)

  1. Elektrische Zünder (1) mit einer leitenden pyrotechnischen Zündzusammensetzung (4) in Berührung mit einer pyrotechnischen Nutzlast (3) und zwei Elektroden (5,9) in elektrischem Kontakt mit der leitenden pyrotechnischen Zusammensetzung (4), wobei der Zünder auch ein resistives Element (6) enthält, das mit der leitenden pyrotechnischen Zusammensetzung (4) parallel geschaltet ist, gekennzeichnet dadurch, daß der elektrische Widerstand des resistiven Elements (6) einen Wert nicht gleich Null und sehr viel kleiner als 0,8 Mal dem Wert des statischen Widerstands der leitenden pyrotechnischen Zusammensetzung (4) im Zünder aufweist, und besagter elektrischer Widerstand gleich oder kleiner ist als 20 Ohm.
  2. Elektrischer Zünder gemäß Anspruch 1, gekennzeichnet dadurch, daß das resistive Element (6) einen elektrischen Widerstand zwischen 0,5 und 10 Ohm hat.
  3. Elektrischer Zünder gemäß Anspruch 2, gekennzeichnet dadurch, daß das resistive Element (6) einen elektrischen Widerstand in der Größenordnung von 2 Ohm hat.
  4. Elektrischer Zünder gemäß einem der Ansprüche 1 bis 3, bei dem eine der Elektroden mit dem äußeren Mantel (2) des Zünders (1) in Berührung ist, und die zweite Elektrode aus einem Metallkörper (5) besteht, der koaxial zum Mantel (2) angebracht ist, gekennzeichnet dadurch, daß das resistive Element (6) aus einem leitenden Näpfchen besteht, das zwischen den Metallkörper (5) und den Mantel (2) eingeklemmt ist.
  5. Elektrischer Zünder gemäß Anspruch 4, gekennzeichnet dadurch, daß der Metallkörper (5) eine ebene Fläche (10) aufweist, auf der eine Isolierscheibe (8) angebracht ist, und dadurch, daß die zweite Elektrode aus einer Metallschale (9) besteht, die mit der Isolierscheibe in Berührung ist, wobei der zylindrische Hohlraum, der von den beiden Scheiben gebildet wird, mit der leitenden pyrotechnischen Zusammensetzung (4) gefüllt wird.
  6. Zünder gemäß einem der Ansprüche 4 oder 5, gekennzeichnet dadurch, daß das Näpfchen (6) aus Kunststoff mit Gehalt an leitendem Pulver hergestellt wird.
  7. Zünder gemäß Anspruch 6, gekennzeichnet dadurch, daß das Näpfchen (6) aus Thermoplastwerkstoff besteht.
  8. Zünder gemäß Anspruch 7, gekennzeichnet dadurch, daß das Näpfchen (6) 3 bis 10 % Graphitpulvergehalt aufweist.
  9. Zünder gemäß einem der Ansprüche 1 bis 8, gekennzeichnet dadurch, daß die leitende pyrotechnische Zusammensetzung mindestens einen Hauptsprengstoff enthält.
EP93402426A 1992-10-06 1993-10-04 Elektrischer Zünder mit leitender Zusammensetzung Expired - Lifetime EP0592292B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9211843 1992-10-06
FR9211843A FR2696539B1 (fr) 1992-10-06 1992-10-06 Amorce electrique a composition conductrice.

Publications (2)

Publication Number Publication Date
EP0592292A1 EP0592292A1 (de) 1994-04-13
EP0592292B1 true EP0592292B1 (de) 1997-01-08

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EP93402426A Expired - Lifetime EP0592292B1 (de) 1992-10-06 1993-10-04 Elektrischer Zünder mit leitender Zusammensetzung

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EP (1) EP0592292B1 (de)
AT (1) ATE147503T1 (de)
DE (1) DE69307250T2 (de)
FR (1) FR2696539B1 (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AR050428A1 (es) * 2004-07-21 2006-10-25 Detnet Internat Ltd Un detonador electronico y metodo para ajustar el voltaje de no-disparo de dicho detonador

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2436963A1 (fr) * 1978-09-19 1980-04-18 France Etat Amorce electrique a composition conductrice
US5027707A (en) * 1989-05-08 1991-07-02 Olin Corporation Electric primer with reduced RF and ESD hazard

Also Published As

Publication number Publication date
FR2696539A1 (fr) 1994-04-08
DE69307250D1 (de) 1997-02-20
EP0592292A1 (de) 1994-04-13
DE69307250T2 (de) 1997-05-15
FR2696539B1 (fr) 1995-10-20
ATE147503T1 (de) 1997-01-15

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