Ordnance – Shields – With explosive device
Reexamination Certificate
1999-11-23
2001-12-11
Johnson, Stephen M. (Department: 3641)
Ordnance
Shields
With explosive device
Reexamination Certificate
active
06327955
ABSTRACT:
BACKGROUND OF THE INVENTION
The technical scope of the invention is that of active protection devices for a wall, notably of a vehicle wall.
We know, notably by patent FR-A-2,436,361 a (so-called reactive) protection device that is intended to be fastened to the outer wall of an armored vehicle. This device comprises a sheet of explosive placed between two metallic plates.
When the jet of a shaped charge impacts on the outer metallic plate, the explosive it contains is ignited. Its detonation cause the metallic plate to be projected outwards towards the jet, thereby consuming it and hence reducing its piercing capability. Such a type of armor is not effective enough against APFSDS projectiles or against cores generated by explosively-formed projectiles.
Indeed, as far as the APFSDS projectiles are concerned, the time of interaction between the projected plate and the projectile is much too short for the piercing capability of the projectile to be sufficiently reduced.
With respect to explosively-generated cores, more often than not the cores pass through the reactive armor without igniting the explosive.
Solutions are sought to overcome such drawbacks.
Thus, patents FR-A-2,730,805 and FR-A-2,679,022 propose the combination of reactive armor with a device to detect the onset of the projectile. The plate is projected onto the projectile before it has impacted the armor. The disturbance to the projectile is thus much greater.
However, such armors have further drawbacks. The protective modules are firstly too heavy since they implement substantial masses of explosive and multiple armor plates.
It is therefore not possible to ensure the protection of light vehicles using such devices, nor is it possible to protect tank turrets against attacks from the roof. Nor are these devices able to be used to ensure protection against explosively-formed projectiles.
Indeed, the detection of the onset of the core is very complicated because of its small dimensions (length less than 120 mm, diameter less than or equal to 40 mm).
Reactive armor known by patent FR-A-2,436,361 is more particularly intended for protection against shaped charges. However, they are presently ineffective against so-called tandem charges (described, for example, by patent FR-A-2,577,037). Indeed, these charges incorporate a main rear charge associated with a small front charge whose purpose is to ignite the reactive armor before the arrival of the rear charge, or else to pierce a hole in the reactive armor without igniting it thereby allowing the jet from the main charge to pass through without disturbance.
SUMMARY OF THE INVENTION
The aim of the invention is to propose an active protection device that does not have such drawbacks.
Thus, the protection device according to the invention is both lighter and more compact than known devices, thereby allowing its installation on lightly-armored vehicles and on turrets.
The subject of the invention is thus an active protection device for a wall, notably a vehicle wall, comprising at least one shaped charge having a direction of action substantially parallel or else inclined with respect to the vehicle wall as well as detection means ensuring the triggering of the shaped charge in reply to the onset of a projectile, wherein such device incorporating at least four shaped charges arranged in at least one casing, said shaped charge being arranged on one side of a quadrilateral.
According to a first embodiment, the casing can enclose four dihedral shaped charges forming a quadrilateral and having converging directions of action.
One of the advantages of this first embodiment of the invention implementing dihedral charges lies in that it ensures better protection than known devices against APFSDS projectiles and even against cores generated by shaped charges.
The directions of action of the shaped charges can be inclined with respect to the vehicle wall and oriented towards the outside of the vehicle.
The detection means can comprise at least one panel comprising at least two electrical contacts closed off by the impact of a projectile.
The detection means can also comprise four independent contact panels, each panel controlling the triggering of a different dihedral charge.
The detection means can comprise at least one panel incorporating a conductor cable broken by an impacting projectile.
Advantageously, the detection means can comprise at least two cables broken by the impact of a projectile, each cable being arranged such as to go alternatively from a first edge of the panel to a second edge parallel to the first making a cover of the panel by means of a network of substantially parallel lines, the lines of the network being formed by a first cable perpendicular to those of the network formed by a second cable such as to form a grid on the panel surface.
The detection means can in that case also comprise a control system to ensure measurement of the resistance of the detection cables, such as to locate the impact point of the projectile on the panel, and that controls the triggering of the dihedral charge nearest the point of impact.
According to a variant embodiment, delay means can be provided to ensure the sequential ignition of the other charges after the ignition of a first charge.
According to a second embodiment of the invention, the active protection device is characterized in that the casing encloses at least four cylindrical shaped charges, each of such charges being arranged on the side of a quadrilateral and the directions of action of such charges being inclined with respect to the vehicle wall.
According to this second embodiment, the invention ensures a protection against shaped charges and notably against tandem shaped charges.
The device according to the invention can incorporate at least two casings and the detection means can comprise at least one electromagnetic or optical central sensor, such sensor being connected to computation means that determine the approach direction of a projectile and its velocity and that controls the ignition of at least one charge from one of these casings.
REFERENCES:
patent: 3893368 (1975-07-01), Wales, Jr.
patent: 4051763 (1977-10-01), Thomanek
patent: 117865 (1900-08-01), None
patent: 977 984 (1974-09-01), None
patent: 23 37 248 (1975-02-01), None
patent: 9 78 036 (1976-09-01), None
patent: 29 06 378 C1 (1990-11-01), None
patent: 42 26 897 C1 (1998-11-01), None
Kerdraon Alain
Lefebvre Gérald
Toussirot Jean-Paul
Vives Michel
Giat Industries
Johnson Stephen M.
Oliff & Berridg,e PLC
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