Explosive material sensitivity control

Abstract

An armor module and an explosive material therefore, which explosive material is normally retained at a less sensitive position, and upon demand it is modified into a more sensitive position, where its initiation ability is upgraded and wherein the modification is carried out by heating the explosive material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carried out in practice, some embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which:

FIG. 1 is a representation of a battle vehicle fitted with reactive armor modules according to the present invention;

FIG. 2A is an enlargement of a reactive armor module in accordance with a specific embodiment of the present invention;

FIG. 2B is a section along line II-II in FIG. 2A;

FIG. 3A is an isometric view of a reactive module in accordance with a modification of the present invention;

FIG. 3B is a section along III-III in FIG. 3A;

FIG. 4 is a schematic draft illustrating the mass efficiency Vs. temperature of different applications of armors; and

FIG. 5 is a schematic representation of a hollow charge fitted with a booster and a heating assembly, according to an application of the present invention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

In FIG. 1, there is illustrated a combat vehicle 10 fitted on its exterior with a plurality of reactive armor modules 12 (as known per se, different configurations of reactive armors are fixed on the exterior of the vehicle to conform to the shape thereof).

In FIG. 2A, there is a illustrated schematically, a reactive armor module 12 which is in the shape of a closed cassette fitted with an electric socket 14 electrically coupled to a power supply and control system (not shown) controllable by personnel of the combat vehicle 10. However, the module may be fitted within more than one cassette.

As can be seen in FIG. 2B, the reactive armor module comprises a cassette 20 adjoining cover 24 of the armor module 12. The cassette 20 comprises a layer of explosive material 20A embedded between two plates 20B and, 20C, e.g. metal plates. Secured to the inner plate 20C, there is a heating element 28 electrically coupled to electric socket 14. The space 32 between the cassette 20 and the bottom cover 26, and the space 36 between the cassette 20 and the top cover 24 may be filled with a thermally isolating material e.g. foamed material, etc.

It is noticed that the armor module may include several cassettes and each cassette may be multi-layered. Furthermore, the thickness and component materials of each cassette may differ depending on the particular design of the reactive armor.

Furthermore, in an application comprising several cassettes in an armor module, the heating elements may be designed to yield different heat capacity for each of the cassettes, e.g. corresponding with the thickness of the explosive material and of the plates. It is also possible to sequentially heat the cassettes at a desired sequence.

According to other modifications, not illustrated, one or more of the cassettes fitted in a reactive module may comprise more than one layer of explosive material intermediately disposed between layers of metal, rubber, ceramic material, composite material, etc., wherein the thickness of such plates may be similar or different, as per different embodiments.

Turning now to FIGS. 3A and 3B, there is illustrated a modification of an armor module assembly in accordance with the present invention generally designated 40 wherein a reactive armor module 42 is attached to a heat exchanger plate 44.

The heat exchanger 44 comprises an inlet conduit 46 coupled to a source of hot fluid (e.g. cooling liquid of an engine of the vehicle 10 or, to a gas exhaust system thereof), and a plurality of undulating heat pipes 48 terminating at an outlet tube 50, which is either connected back to the heating source (e.g. in the case of a cooling liquid system) or out to the atmosphere (in case of a gas exhaust system). The arrangement is such that fluid flowing through conduits 48 transfers heat to the heating surface 52 of the heat exchanger 44, which in turn transfers heat to the cassette plate 58B and in turn to the explosive material 56 within the armor module 42 (in this case, the explosive material 56 is disposed between two conductive plates (e.g. metal plates 58A and 58B).

The arrangement in accordance with the present invention is such that heat is controllably and selectively applied to the reactive armor module so as to increase its efficiency between different sensitivity levels.

By one example a reactive armor module is heated so as to change its efficiency between a so-called safe position, namely a position at which the explosive material is insufficiently sensitive to initiate by a kinetic projectile, and a so-called armed position, namely such that upon striking by a kinetic projectile the explosive material will detonate to obtain the required protective effect.

In the schematic graph of FIG. 4, there are illustrated three types of explosive reactive armor concepts and the change of their mass efficiency (E, defining the ratio between the armor's mass and the equivalent mass of armor steel for obtaining the same performance) Vs. the explosive temperature (T expressed in degrees, centigrade). Line I represents how an explosive material which at a normal, unheated stage is completely inert to long kinetic projectiles (the term long kinetic projectiles as referred to herein calls for projectiles wherein the diameter is substantially low with respective to their length), though upon heating of the explosive material it becomes effective to a certain degree against such projectiles.

Line II illustrates a self limiting explosive material (fitted in SLERA) which at the normal, unheated position, will react locally against a hollow charge (namely, the explosive material will react at a restricted area only) whilst upon heating thereof will result in enhancement of the reaction zone up to complete detonation of the explosive material within the reactive armor. Heating may be, for example, up to 150° C.

Line III represents an explosive material, e.g. LBR6, which at the normal, non-heated position will detonate completely whilst upon heating up to about 150° C. will significantly improve the efficiency of the armor module holding the explosive material.

In FIG. 5 of the drawings there is illustrated a hollow charge generally designated 70, fitted with a sensitivity control system according to an application of the present invention. The hollow charge comprises a main charge 72 formed with a V-like fore-end and fitted with a liner 74 as known per-se, extending before the domed hollow head 76. A booster 80 is fitted at a rear end, slightly extending into the main charge, said booster 80 fitted within a heating sleeve 84 which in turn may be fitted with a thermally isolating jacket 86. A detonator/fuse 88 extends into the booster 80, fitted with an igniter cord 89. The heating sleeve 84 comprises an electric supply line 92 for powering a heating array and there is further provided a sensor 96 electrically coupled by wiring 98 to a control unit (not shown) for indicating the status of the booster in terms of temperature or ‘safe’/‘armed’ positions.

An advantage of this system is that the detonator 88 may be permanently fixed to the booster 80 and its arming may be readily obtained by heating. This is in contrast to the need in some known systems to keep the detonator separate from the booster and hollow charge (for safety reasons) unless it is to be used.

Whilst some embodiments have been described and illustrated with reference to some drawings, the artisan will appreciate that many variations are possible which do not depart from the general scope of the invention, mutatis, mutandis.

Claims

1. An explosive material which is normally retained at a less sensitive position, and upon demand it is modified into a more sensitive position, where its initiation ability is upgraded and wherein said modification is carried out by heating the explosive material.

2. An explosive material according to claim 1, wherein the explosive material is converted from a substantially insensitive composition into a sensitive composition.

3. An explosive material according to claim 1, wherein sensitivity level of the explosive material and its performance are upgraded, however upon demand.

4. An explosive material according to claim 1, wherein the explosive material is applied in a list of articles including, among others, reactive armor modules, boosters, warheads, mines and the like.

5. An explosive material according to claim 1, wherein heat is applied by a flexible sheet adjoining the explosive material and embedding therein conductive elements arranged in a predefined pattern.

6. An explosive material according to claim 5, wherein the flexible sheet is a flexible elastomeric sheet.

7. An explosive material according to claim 1, wherein a heating element is integrated with the explosive material during or after its manufacture.

8. An explosive material according to claim 1, wherein one or more thermocouples are embedded in the explosive material for providing indication regarding temperature of the explosive material, so as to obtain indicia of its sensitivity level and/or whether the explosive material is in a ‘safe’ or ‘armed’ position.

9. A method for modifying sensitivity of an explosive material between a less sensitive position and a more sensitive position, where its initiation ability is upgraded, wherein said modification is carried our by heating the explosive material.

10. A method according to claim 9, wherein the explosive material used is substantially less sensitive than an explosive material which would have been used so as to obtain an equivalent effect/functional result, though without heating.

11. A method according to claim 9, wherein the entire explosive material is heated, or only selective portions thereof, depending on a particular application.

12. A method for storage, handling and safe transportation of explosive material wherein the explosive material is maintained at room temperature until prior to use.

13. An armor module comprising one or more plates and layers of explosive material, wherein the explosive material is normally retained at a less sensitive position, and upon demand it is modified into a more sensitive position, where its initiation ability is upgraded, wherein said modification is carried our by heating the explosive material.

14. A reactive armor module according to claim 13, wherein the heating capacity range is about 0.2-2.0 Watt/cm2, where the resultant heating of the explosive material is in the range of about 70-150° C.

15. A reactive armor according to claim 13, wherein a thermally isolating jacket is provided over the reactive armor module.

16. A booster of a rocket/missile comprising a detonator for initiating an explosive material and a heating element for applying heat to said explosive material.

17. A booster according to claim 16, wherein one or more sensors are provided for generating a signal corresponding with the temperature of the explosive material and its sensitivity.

18. A booster according to claim 16, wherein sensitivity of the explosive material may be altered from a ‘safe position’ wherein the explosive material is substantially insensitive and is not likely to detonate, into an ‘armed position’ wherein the explosive material is sufficiently sensitive so as to detonate upon initiation.