Cartridge

Details Cartridge Cartridge

2001-04-23

2003-04-01

Tudor, Harold J. (Department: 3641)

Ammunition and explosives

Cartridges

Case

C102S430000, C102S431000, C102S202000, C102S202500, C102S202900

Reexamination Certificate

active

06539874

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to a cartridge having an electrothermal ignition device.
Significantly greater acceleration effects can be achieved for projectiles fired from guns with the use of high-energy propellant-charge powders, particularly NENA propellant-charge powder (NENA=N(2-nitroxy)nitraminethane) or DNDA propellant-charge powder (DNDA=dinitro-diaza-alkanes), than with conventional propellant-charge powders. Typically, the firing-gas temperature of such propellant-charge powders, and thus the barrel erosion, are lower than with other known powders. The high activation energy of the high-energy propellant-charge powders, however, impedes ignition with the aid of pyrotechnical ignition charges. The reduced ignitability of the propellant-charge powder also leads to an increase in the ignition delay times, and an increased scattering of the ignition times.
To assure a reliable, rapid ignition of a cartridge, e.g., with NENA propellant-charge powder, it has proven advantageous to employ an electrothermal ignition device instead of a pyrotechnical ignition charge. In this case, a high current flows through a wire-type conductor in the floor-side region of the corresponding cartridge such that the conductor vaporizes explosively and generates a high-energy arc. This arc then ignites the corresponding propellant-charge powder.
As the Applicant's experiments have revealed, in this type of electrothermal ignition device, the relatively heavy dependency of NENA propellant-charge powder on temperature, which leads to a corresponding dependency on the acceleration effect, can be compensated with the quantity of electrical energy supplied to the plasma-ignition system.
A drawback of this electrothermal ignition device is that the generation of the floor-side or base-side arc only effects the ignition of a relatively small percentage of the propellant-charge powder, and, often, no reproducible combustion behavior of the propellant-charge powder results, This is particularly true with propellant-charge powders that are difficult to ignite.
To obtain a reproducible combustion behavior of the propellant-charge powder, German patent Application DE 199 21 379.8, corresponding with Patent Application GB 2,349,940, published Nov. 15, 2000, proposes disposing the wire-type conductors inside tubes also comprising propellant-charge powder extending through the propellant charge, rather than leading the wire-type conductors directly through the propellant-charge. These propellant-charge-powder tubes then constitute ignition conduits inside the propellant-charge structure. In the activation of the ignition device, first the wire-type conductor vaporizes and an arc plasma conduit forms inside the respective propellant-charge-powder tubes. Radiation-transport mechanisms transport the energy to the environment by way of the plasma conduits. This energy transport leads to a rapid ignition of the propellant-charge-powder tubes and their fragmentation. The burning fragments (hot spots) of the propellant-charge-powder tubes, and the released arc radiation, effect a rapid, uniform ignition of the propellant-charge structure.
It has been seen, however, that, in the use of propellant-charge-powder tubes comprising graphitized propellant-charge powder, which is widely available commercially, a relatively large amount of electrical energy is necessary for attaining an adequate ignition interaction with the propellant-charge powder.
In view of the not-previously-published German patent application document DE 199 21 379.8, it is the object of the invention to disclose a cartridge in which even propellant-charge powders that are difficult to ignite, particularly NENA or DNDA propellant-charge powders, can be ignited rapidly and reliably with the smallest possible requirement of electrical energy.
SUMMARY OF THE INVENTION
The above object generally is achieved according to the present invention by a cartridge with an electrothermal ignition device, which comprises a cartridge including a combustible sleeve that is at least partially filled with a first propellant-charge powder, and a metal base connected to one end of the sleeve and forming the base of the cartridge. A high-voltage electrode extends through and is insulated from the base, and an electrically-conductive wire, which extends axially through the first propellant-charge powder, has a first end connected to the high-voltage electrode and a second end connected to an electrical contact disposed in the forward region of the propellant-charge sleeve for contacting the inner wall of a gun barrel when the cartridge is fired. The electrically-conductive wire is guided axially through a tube that is formed of a second propellant-charge powder and that is disposed in the first propellant charge powder along at least an axial portion of the propellant-charge sleeve. The second propellant-charge powder forming the tube is an optically transparent propellant-charge powder.
Further advantageous embodiments of the invention are disclosed.
The invention is essentially based on the concept of using transparent propellant-charge-powder tubes. Nitrocellulose powder, particularly the type known as JA2, has proven especially effective as a propellant-charge powder. To assure the transparency of this propellant-charge powder, it cannot contain any black components, and the conventional graphitization of the outside surface must be omitted.
The use of optically transparent propellant-charge-powder tubes permits the radiation emitted by the plasma conduits to reach the propellant-charge structure of the cartridge without large absorption losses. Furthermore, the plasma radiation effects a change in the combustible surface of the transparent propellant-charge-powder tubes, which leads to a significantly accelerated conversion of the tubes, and thus supports the ignition process. The utilization of these properties results in a distinct reduction in the requirement of electrical energy for the plasma-ignition system.
It has also been seen that, with the use of optically transparent propellant-charge-powder tubes, the requirement for additional electrical energy for the temperature compensation of the NENA propellant-charge powder is reduced in comparison to that of non-transparent tubes.
With the use of DNDA propellant-charge powder, this additional electrical energy can be omitted, because the DNDA propellant-charge powder burns extensively independently of the temperature.
Further details and advantages of the invention ensue from the exemplary embodiment described below in conjunction with drawing figures.


REFERENCES:
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patent: 6309484 (2001-10-01), Langlotz
patent: 6332402 (2001-12-01), Weise et al.
patent: 6332403 (2001-12-01), Weise et al.
patent: 6354218 (2002-03-01), Weise et al.
patent: 198 34 058 (2000-02-01), None
patent: 2 349 940 (2000-11-01), None
patent: WO 00/17598 (2000-03-01), None

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