EP1148313B1 - Electrothermal ignition device for an ammunition cartridge and its manufacturing process - Google Patents

Description

The invention relates to an electrothermal ignition device for igniting the powder propellant charge of a cartridge according to the preamble of claim 1.

Such a device is known from US Pat. No. 5,287,791.

In known cartridges with electrothermal ignition device is to ignite the propellant charge powder in the bottom region of the corresponding cartridge a wire-shaped conductor of flows through such a high current that it evaporates explosively and an arc discharge initiates. About this arc discharge is then the corresponding propellant charge powder set on fire.

It has proved to be disadvantageous that in a purely electrothermal ignition the entire, necessary for reproducible ignition energy can be provided electrically got to. This results in a high demand for electrical energy.

In the unpublished patent application DE 199 21 379.8 (which as internal priority for the publication with the number DE 19 936 650 A served) is further described the wire-shaped conductor does not pass directly through the propellant, but within to arrange from existing propellant powder tubes. These propellant powder tubes then form within the propellant charge Ignition.

When the ignition device is activated, the wire-shaped conductor first evaporates, and an arc plasma channel is formed inside the respective propellant charge powder tubes. Via the plasma channels, the energy is released via radiation transport mechanisms to the environment. This energy output leads to a rapid ignition of the propellant powder _- tubes and to implement them. The resulting propellant gases of the propellant charge powder tubes and the released arc radiation cause a rapid and uniform lighting of the surrounding propellant charge buildup.

In the unpublished DE 199 21 379.8 (cf., Laid-Open Publication DE 19 936 650 A) is also described the electrically conductive To replace wires with a metallization, the inside of the propellant charge powder tubes is applied.

Starting from DE 199 21 379.8 (cf., Laid-Open Publication DE 19 936 650 A), the invention is based on the object of an ignition device specify at the for the ignition of the powder propellant charge a reduced Need for electrically supplied energy is required, with the advantageous properties the electrothermal ignition can continue to be used.

This object is achieved by the Features of claim 1 solved. Further, particularly advantageous embodiments of the invention reveal the dependent claims.

The invention is based essentially on the idea not to introduce the electrically conductive wire in a propellant charge powder tube, but to coat with a pyrotechnic ignition charge. An admixture based on potassium perchlorate-zirconium (KClO ₄ -Zr) has proven to be advantageous.

Preferably, this mixture is a polymeric binder from the series of fluoroalkanes added, which causes the primer from a solvent emulsion on out Wires can be applied and after evaporation of the solvent firmly on the wire liable. In addition, the binder content also gives the ignition charge adhering to the wire elastic properties.

After initiation of the ignition charge by a current flowing through the wire, the mixture is reacted and zirconium oxide (ZrO ₂ ) is formed at temperatures around 4000 ° C which, as fine hot spots, promotes the ignition of the propellant charge powder and reduces the need for electrical energy.

Fig.1 den Längsschnitt durch eine Patrone mit einer erfindungsgemäßen Anzündvorrichtung, welche einen elektrisch leitenden, einen homogenen Durchmesser aufweisenden Draht umfaßt, der mit einem Anzündsatz beschichtet ist;

Fig.2 die vergrößerte Darstellung eines Querschnittes durch den beschichteten Draht entlang der in Fig. 1 mit II-II bezeichneten Schnittlinie;

Fig.3-5 drei Längsschnitte durch elektrisch leitende Drähte, die jeweils mit einem Anzündsatz beschichtet sind und unterschiedlich ausgebildete Durchmesser aufweisen.

Further details and advantages of the invention will become apparent from the following with reference to figures explained embodiments. Show it:

1 shows the longitudinal section through a cartridge with an ignition device according to the invention, which comprises an electrically conductive, homogeneous diameter wire, which is coated with a Anzündsatz;

FIG. 2 shows the enlarged illustration of a cross section through the coated wire along the section line designated II-II in FIG. 1; FIG.

Fig.3-5 three longitudinal sections through electrically conductive wires, which are each coated with a Anzündsatz and have different diameters formed.

In Fig. 1, 1 denotes a cartridge (e.g., for firing from an armored weapon), which is connected to the ignition via a switch 2 with a power source 3. The corresponding Weapon in which the cartridge 1 is, is not for reasons of clarity shown.

The cartridge 1 comprises a filled with a propellant charge 4 sleeve 5 and a propellant charge sleeve 5 bottom end sleeve bottom 6. The combustible sleeve 5 is in Area of its sleeve bottom end 7 form fit between an insulating molding. 8 and the sleeve bottom 6 fixed.

In the sleeve bottom 6 is centered with respect to this electrically insulated high voltage electrode 9 arranged, which passed through the Isolierformteil 8 and with a Metal disc 10 is connected.

On the metal disk 10 is an electrically conductive wire 11 with homogeneous over its length Fixed diameter, which is coated with a primer 12 (Fig.2). in the The area of the sleeve cover 13 of the propellant charge tube 5 is the wire 11 with an annular Contact part 14 connected, which in turn is the lying at ground potential inner wall contacted the weapon, not shown.

To shoot the cartridge 1, the switch 2 is closed and with a number Power source 3 charged by charged capacitors (at a voltage of up to 40) kV) discharged suddenly. The occurring discharge current leads to an explosive Evaporation of the wire 11 and to initiate an arc plasma on the entire Length of the wire. Due to the interaction of the arc plasma with the Ignition rate 12, its initiation over the entire length of the coating 12 is effected and the resulting pyrotechnic particles are in the propellant charge 4th hurled.

3 shows the structure of an arc-introducing wire 15 with inhomogeneous diameter, which is covered with a primer 16. When initiating a corresponding high current in the wire 15, this is initially in the areas 17 with low Diameter explosively evaporated. In these areas therefore begins first the formation of arc plasmas and their interaction with the initial charge 16. Time offset then occurs the formation of arc plasmas in the areas 18th of the wire 15, which have a larger diameter. About the wire thickness and / or via the current waveforms, the desired time delay of the generation of the plasmas be set in the propellant charge. About the distances of the wire inhomogeneities can a corresponding spatial distribution of the plasmas are generated.

4 shows an electrical wire 19 with conically formed in the direction of the longitudinal axis Diameter course, which is coated with a primer 20. At initiation a correspondingly high current, the explosive evaporation takes place first at the point 21, at which the wire 19 has its smallest diameter and then moves in the direction of increasing the diameter. With such a structure Ignition operations can be generated in the longitudinal direction of the wire 19 in time run in a controlled manner. The process speeds are determined by the wire geometry and / or adjusted by the shape of the current pulse.

The same considerations apply to the embodiment illustrated in FIG. wherein an electrical wire 22 is a step-shaped increase in the diameter having.

For example, the ignition set by appropriate additives be electrically conductive.

LIST OF REFERENCE NUMBERS

1

cartridge

2

switch

3

power source

4

Propellant charge, powder propellant charge

5

Sleeve, propellant sleeve

6

sleeve base

7

The End

8th

insulating mold

9

High-voltage electrode

10

metal disc

11

wire

12

Primary charge, coating

13

casing cover

14

contact part

15

wire

16

ignition

17

Area

18

Area

19

wire

20

ignition

21

Job

22

wire

Claims (5)

1. Electrothermal initiation apparatus for initiation of the powder propellant charge (4) of a cartridge (1) having at least one electrically conductive wire (11; 15; 19; 22) which extends at least partially through the propellant charge (4) in the direction of the longitudinal axis of the respective cartridge (1), and can be connected to an electrical power source (3), with a sufficiently high current flowing through the electrical wire (11; 15; 19; 22) for initiation of the propellant charge (4) that the electrical wire (11; 15; 19; 22) is vaporized explosively and initiates an arc discharge which then initiates the propellant charge (4), characterized in that the electrically conductive wire (11; 15; 19; 22) is coated with a pyrotechnic initiation charge (12; 16; 20) in at least one subarea.
2. Initiation apparatus according to Claim 1, characterized in that the wire (11; 15; 19; 22) has a homogeneous, inhomogeneous, conically widening diameter, or a diameter which is enlarged in steps, corresponding to the desired initiation behaviour of the initiation apparatus within the initiation charge (12; 16; 20).
3. Initiation apparatus according to Claim 1 or 2, characterized in that the initiation charge (12; 16; 20) is made electrically conductive by appropriate additives.
4. Initiation apparatus according to one of Claims 1 to 3, characterized in that the pyrotechnic initiation charge (12; 16; 20) is a mixture based on potassium perchlorate zirconium (KClO₄-Zr).
5. Initiation apparatus according to Claim 4, characterized in that the potassium perchlorate zirconium mixture contains a polymer binding agent from the group of fluoroalkanes.

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