Ammunition and explosives – Igniting devices and systems – Multiple mode fuzes
Reexamination Certificate
1998-07-01
2001-06-12
Jordan, Charles T. (Department: 3643)
Ammunition and explosives
Igniting devices and systems
Multiple mode fuzes
C102S499000
Reexamination Certificate
active
06244184
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to fuzes in general and, in particular, to self-destruct fuzes for submunitions.
BACKGROUND OF THE INVENTION
In recent years there has been great development of smart munitions, including cluster bombs which fire a plurality of submunitions or submunition grenades inside a single casing which opens over the target to release the submunitions within, and their increasing use around the world against a variety of targets. However, conventional submunition grenades have a number of disadvantages. The use of submunition grenades having a shaped charge and a simple inertial impact fuze is effective against armoured targets, but is is limited in its efficacy against area targets.
Conventional submunition grenades also suffer from undesirable initiation of fuzes due to collisions in air by submunition grenades, i.e., immediately after their expulsion. This lowers the reliability of the system, leads to loss of the submunition grenade, damages neighboring submunition grenades by the explosion, and creates duds.
Furthermore, the increasing use of submunition grenades creates a large quantity of duds which endanger friendly forces. These duds can be used by the enemy as booby traps, and call for substantial resources to clean the affected area, in order to permit its use by civilians. In addition, the heavy metals and other materials found in the batteries of many of the conventional submunition grenades′ fuzes damages the ecology of the area in which they fall.
One solution to this problem is provided by Tari et al, in U.S. Pat. No. 5,387,257 which describes a self-destruct fuze for submunition grenades. The fuze includes an electrical self-destruct unit which is operative in the event that the mechanical primary inertial impact mode fails to operate upon striking an intended target. This fuze includes all the components for a conventional impact fuze, as well as an entirely separate electric self-destruct system. The fuze is relatively large, to accomodate the mechanical impact detonator and the battery. The fuze is problematic for several reasons: the batteries include heavy metals and other materials which damage the environment; the chemicals in the batteries age, but the batteries cannot be replaced since it is difficult to reach them in each grenade; the fuze includes a mechanical striker which, in the case of a dud, can be activated accidentally by friendly forces, or can be used to initiate the submunition grenade as a booby trap; the reserve battery in the fuze can be activated by transportation vibration, whereby there will be no electricity to initiate the detonator at the time of firing the submunition grenade in the case of a dud.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a fuze for a submunition grenade which includes an electric detonator, primary apparatus for electrically initiating the electric detonator, and self-destruct apparatus for electrically initiating the electric detonator, after a period of time, when the primary apparatus fails to detonate the detonator. Preferably, the fuze has no internal energy source, but only a capacitor which is charged by an external energy source.
According to a preferred embodiment of the invention, the submunition grenade includes an electric detonator, and the primary apparatus includes an integrated circuit, an impact switch coupled to the integrated circuit, and an electric resistor bridge coupled to the electric detonator and to the integrated circuit for initiating the electric detonator in response to activation of the impact switch.
Further according to a preferred embodiment, the self-destruct apparatus includes a timer, and an integrated circuit for initiating the electric detonator after passage of a predetermined time in response to activation by the timer.
There is also provided in accordance with the present invention a method of initiating a submunition grenade having a fuze and an electric detonator, the submunition grenade being arranged to be ejected from a projectile, the method including the steps of releasing the submunition grenade from the projectile, electronically counting an inhibition time, and electrically initiating an electric detonator by a primary initiator.
According to a preferred embodiment of the invention, if the primary initiation does not cause the detonator to explode, the method further includes the steps of electronically counting time to self-destruct, and electrically initiating the electric detonator by means of a self-destruct initiator.
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Israel Military Industries Ltd.
Jakel Kevin
Jordan Charles T.
Wolf Greenfield & Sacks P.C.
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