FR2670574A1 - ELECTRO-MAGNETIC SHIELD WITH CONDUCTIVE PLATES. - Google Patents

Abstract

The electromagnetic shielding, in particular against metal projectiles, preferably arrow projectiles, shaped charge jets, and similar devices, comprises at least two plates (12 '; 14') of conductive material (conductive plates) arranged one behind the other with respect to the direction of flight of the projectile and at a certain distance from the other, at least one of the plates being brought to an electric potential. At least one capacitor (34) is connected in parallel with at least two conductive plates (12 ', 14'). Use to improve the protection of armor against projectiles.

Description

The invention relates to an electro-

  magnetic, in particular for the protection against

  metal projectiles, preferably projectiles-

  arrows (made of steel), hollow charge jets, and the like, with at least two plates of conductive material disposed at a distance from each other with respect to the direction of flight of the projectile, one at

  less plates being brought to an electric potential.

  Vehicles and conventional armored buildings are shielded with materials whose protective effect is solely their mechanical stability Impact projectiles can not pierce conventional shields, but bounce off them or are not in the situation of the piercing In addition, there is obviously a question of caliber and velocity of the projectile used to pierce the conventional armor For the armored buildings, it is possible simply to carry out the shielding in the form of reinforced concrete walls or even more thick, and therefore more resistant, to protect against a larger caliber projectile For vehicles, this procedure is possible only up to a certain order of magnitude of the thickness of the shield, because vehicles with increased armor weight or total weight are increasingly difficult to maneuver C This is particularly the case for airplanes. This is why we have recently developed

  electromagnetic shielding methods and devices.

  magnetic, designed to strengthen the case where the classical main shielding In special cases,

  however, only this shielding can be installed.

  In such a device, called reactive shielding, it is somehow opposed to the projectile incident an object in the form of one or more steel plates of the corresponding armored vehicle Thus, the projectile in approximation, the impact or before the impact, is detected by means of a magnetic field generated by a coil and deflected by the plate or plates Thanks to the mechanical impulse that occurs due to the shock between the projectile and the plates making

  obstacle, the direction of flight of the projectile is changed.

  If there are significant shear forces,

the projectile can break.

  In another known device, the main shield is this time designed as a set of two plates of conductive material, at a distance from one another The two plates are electrically insulated from each other and are maintained under tension, so that the two plates are in principle an open current loop As soon as a projectile passes through the two plates and thus short-circuits them, a flow of the connected current is produced on the projectile. the two plates, as well as the charge stored by the two plates functioning as a capacitor The currents flowing through the projectile have no preferential direction The electric current and the electric charge flow in all directions in the

projectile.

  This device is only adapted to the hollow charge jets, because it is not possible to deploy with the aid of the device described above the energies for

fusion of projectiles-arrows.

  The object of the present invention is to propose an electromagnetic shield which does not have

  disadvantages of the state of the art discussed below.

  above and which is particularly designed to reduce the effectiveness of projectiles-arrow or even reduce it to

nothingness.

  This objective is achieved by means of an electromagnetic shielding, characterized in that at least one capacitor is connected in parallel with at least two

conductive plates.

  According to the invention, a capacitor is connected in parallel to the plates of conductive material disposed at a distance from each other. In this way, the current flowing between the plates in the event of a short circuit has a direction

preferred.

  That is, as soon as a projectile has

  pierced the plates and thus put them on

  circuit, it flows a current, which is mainly generated by the charges stored in the capacitor connected in parallel, for the compensation of the charges by the projectile putting the plates in short circuit Due to the flow of current, there is a generation of a magnetic field oriented perpendicular to the direction of movement of the current Due to the interaction of the magnetic moments of the current affected by a preferential direction and the magnetic field generated by the flow of this current, it is exerted on the projectile a force, the Lorentz force. The Lorentz force, which is exerted on the projectile, results in projectile deflection, or non-functioning due to shear forces Because the projectiles are constituted in all cases by an extremely hard and fragile material they are extremely brittle, which is why the Lorentz force acting on the projectile causes the projectile to break or tilt slightly between the plates due to an oblique impact. leading to being

deflected or broken.

  In principle, this way of proceeding corresponds to an effect characterized by the name "Effect-Railgun". Indeed, a projectile is accelerated between the two conductive plates, whereas there is generation of a flow of current through conductive plates "-t through the projectile The current has a preferred direction and creates a magnetic field perpendicular to the current vector Due to the interaction of the current and the magnetic field, there is new generation of a Lorentz force, which acts on the projectile in the direction of the acceleration Due to the Lorentz force, the projectile is consequently accelerated along the conductive plates, which one can

  consider as guide rails of the projectile.

  Coarse estimates have shown that depending on the weight of the projectile, a projectile can be deflected a few centimeters when the currents between the plates according to the invention and through the projectile to influence flow with an order of magnitude

  about 1 to 3 MIA (mega-amperes).

  In order to surely create a preferential direction for the current that must ultimately flow through the projectile that is to be protected, it is advantageous that the capacitance of the plates is less than the capacitance of the connected capacitor.

parallel on the plates.

  The capacitance of the capacitor must be at least 50 times greater than the capacitance of the plates distant from each other. In this respect, value differences around the factor 100 and above are particularly interesting, in order to store a capacitor. sufficient charge to generate currents with a preferential direction, which can

  also significantly influence projectiles-

bigger arrows.

  For safety reasons, the one of the plates which is the outermost in relation to the direction of flight of the projectile must be grounded, that is to say to the ground The inner plate, or the inner plates can / can be at a very high electrical potential, without the user personnel being able to run a hazard due to a vehicle designed with

the shield according to the invention.

  The plates according to the invention must always have a thickness of at least 2 mm. Minimum thicknesses of 3 to 5 mm have been particularly proven. The minimum thickness is important, so that the currents necessary for the deflection of a larger one projectile can not vaporize the conductive material of the plates It has been shown that thinner conductive plates can be instantly vaporized by the ohmic heat associated with high currents. The plates according to the invention can be kept at a distance from each other by simple spacers, which constitutes an air gap between them. It has however appeared advantageous to place between the plates made of conductive material a

  insulating plate, preferably of dielectric material.

  This provision is indispensable insofar as, in this way, the shielding according to the invention remains durable, without damage affecting its operation, in sometimes difficult use conditions (in maneuvers, traveling in thick forests or in undergrowth) The insulating plate may in particular be made of plastic, for example polyethylene, hard PVC, PERTITTAX, fiberglass-reinforced plastic or the like. Such materials are at least partially adapted, because next to the energy stored in the capacitor connected in parallel, or in the capacitors connected in parallel, they can even more store energy between the plates

conductive themselves.

  From the point of view of the manufacturing technique, it is particularly appropriate to bond the conductive plates to the insulating plate. One of the sides of the shielding according to the invention and intended for the protection of an object must be fixed on the latter, the object being able

to be in particular a vehicle.

  it is appropriate to provide between the shield and the object a bonding material, which may preferably be constituted by an insulating material, such as fiberglass reinforced plastic It is thus ensured that the electromagnetic shield according to the invention can not be unloaded of itself on the object,

in particular the vehicle.

  To further exert a rotational furrow on the projectile perforating the conductive plates, it is advantageous to fix the conductive plates according to the invention on the object to be protected so that the shield has an angle of inclination with respect to the flight direction of the projectile The magnetic field thus has an additional component which creates the moment of rotation which further deviates or weighs on a

projectile passing through.

  A variant of the armor according to the invention can be made in such a way that the anterior plate in the direction of flight of the projectile is not fixed by gluing. Thanks to the repulsive electro-magnetic mechanisms which occur during the discharge and thanks to the incidental projectile, the relevant plate is pushed forward from the vehicle,

  which further enhances the protective effect.

  In the direction of flight of the projectile, and behind the armor according to the invention, it is placed a conventional shield for the protection of the object

  concerned, in particular a vehicle.

  It may also be advantageous not to bind the entire shielding according to the invention in a fixed manner with the main armor, but to do so only with a set

  In this way, other counter impulses

  are transmitted to the shield according to the invention, which, in relation to the deflection of a projectile making an impact, may have a protective effect

sensitive.

  If necessary, it is possible to superimpose several shieldings according to the invention, between which additional layers can be provided to make

obstacle to the projectile.

  The shield according to the invention naturally also offers protection against hollow charges. In this case, the jet is not only vaporized, but can also be removed from its initial trajectory by the forces that appear (Lorentz force, torque, the case In this way, the effect

  residual is further reduced.

  In the following, we explain the forms

  advantageous development of the electronic shielding

  Magnetic device according to the invention, with reference to the accompanying drawings. Further advantages and characteristics relating to the electromagnetic shielding are also presented.

  According to the invention The figures show -

  Figure 1 a sketch for explanation of the "railgun effect"; Figure 2 the principle of the action of the "railgun effect" in the case of electromagnetic shielding according to the invention, in a representation of principle; Figure 3 a cross-sectional view of an electromagnetic shield according to the invention; Figure 4 an electromagnetic shield according to the invention, according to Figure 3, the impact of a projectile; Figure 5 the representation from Figure 4, with rupture of the

projectile.

  With reference to FIG. 1, the "railgun effect" must first be explained. At a predetermined distance, the conductive plates 12 and 14 are placed, which in this case also provide the rails function. On the rails 12 and 14 , an electric current is established which flows by a projectile 16 of the rail 12 to the rail 14 according to the direction arrows 18 a, 18 b, 18 c, 18 d, and 18 e Due to the current, there is generation of a magnetic field oriented perpendicular to the current, which is characterized by an arrow 22 According to the formula for the Lorentz force, this results, that is to say that it results from the interaction between the current and the magnetic field perpendicular to it a force F the Lorentz force, which accelerates the projectile

  16 in the direction of an arrow 20.

  In FIG. 2, it is explained what action the "railgun effect", explained with reference to FIG. 1, has on a projectile 16a that sinks through the

  rails 12 and 14 and thus short circuit.

  It is clearly visible that the current flowing along the indication arrows 18a, 18b, 18c, 18d, and 18e, on the other hand, generates a magnetic field B. This magnetic field B, indicated by FIG. arrow 22, is in interaction with the current J, indicated by the arrow 18c, which flows between the rails 12 and 14 via the projectile Because of this interaction, there is on the other hand generation of a Lorentz force, perpendicular to the plane constituted by the current vector and the magnetic field vector The projectile 16 a, which is rigid with respect to transverse translations perpendicular to the direction of flight of the projectile because of its retention in the holes 12 a and 14 has rails 12 and 14 with respect to movements of this kind, is very sensitive to such constraints because it is made of a very brittle material In this way, the Lorentz force F deployed can cause in addition to the inclination of the

  projectile and at break because of its fragility.

  In FIG. 3, the reference symbol 10 is generally characterized by an interesting form of development of the electromagnetic shield according to the invention. The approximate direction according to which a

  projectile could have an impact on the electro-

  magnetic device according to the invention 10 is figured so

general by the arrow 32.

  As seen in the direction of the arrow 32, the electromagnetic shielding according to the invention 10 consists of a first plate or conductive plate 12 ', which is preferably fixed by a bonding 26a to a plate 24 of insulating material , in particular of dielectric material Faced with the conductive plate 12 ', a second conductive plate 14' is fixed on the insulating plate 24, generally also by a bonding 26b Between this device consisting of the conductive plates 12 'and 14 C as well that by the insulating plate 24 and a main shield 30 of the object to be protected, in particular a vehicle, there is provided a connecting material 28 can also be provided The binding material in the form of a plate, generally constituted also by an insulating material, such as for example polyethylene, hard PVC, pertinax,

  fiberglass reinforced plastic, or the like.

  The conductive plates 12 'and 14' are generally about 2 mm thick. However, it is preferable that this thickness is at least 3 to 5 mm, the thickness of the conductive plates 12 'and 14' being limited to only by considerations of expediency, because on the one hand the electromagnetic shielding must not bring excessive additional weight, and on the other hand the ef- fective effect of deflection of the electromagnetic shield according to the invention is only negligibly affected by a superabundant thickness of the conductive plates 12 '

and 14 '.

  The shielding according to the invention is fixed on an object to be protected, for example by screws, clamps or insulated pins. Fastening by means of strips, cables, or dampers (fluid dampers) is also conceivable, in order to link the shielding according to the invention to the object to be protected certainly solid,

but not rigid.

  On the conductive plates 12 'and 14', a capacitor C (34) is connected in a parallel circuit. In order to be able to transmit very high currents from the capacitor 34 to the conductive plates 12 'and 14', it is necessary to dimension

  consequently the connecting conductors 38a and 38b.

  It is necessary to choose not only the thickness of the connecting conductors 38a and 38b, but also that of the conductive plates 12 'and 14' so as to be able to

  to safely route currents of 3 MA (mega

  1 am amps) Depending on the size of the projectiles, currents of more than 3 MA, for example up to 6 MA, may be needed to attenuate or eliminate

the effect of the projectiles.

  The capacitor C (34) must have a greater capacity, and even a capacity much greater than that of the device consisting of the conductive plates or plates 12 'and 14' in connection with the insulating plate 24 itself In order to constitute a preferential direction for the currents flowing between the conductive plates 12 'and 14' during a short circuit, the capacitor C of the capacitor 34 must be at least in a factor 50, generally at least in a factor 100, greater than that linked to the plate device 12 ', 24,

and 14 '.

  In specific cases, it may be advisable not to bond firmly by gluing the first conductive plate 12 'in the direction of flight of the projectile with the rest of the device, so that this plate 12' can, as a result of the appearance of repulsion forces, shifting forward in the opposite direction to that of the

arrow 32.

  It may also be expedient not to bind the entire conductive plate device 12 ', 24', and 14 'together or, if appropriate, the plate 28 made of bonding material with the main shield 30 of the object to be protected. , in order to take advantage of the elasticity of the material concerned in connection with the deflection of the projectile inside the electromagnetic shield for the purpose of additional protection. In FIG. 4, the electromagnetic shielding according to the invention is provided in the same principle as the embodiment according to FIG. 3. Simply, the conductive plate 12 'placed first in the flight direction 32 of the projectile and this does his 1 'D

  connection with the capacitor 34 are grounded.

  It is thus avoided that the user personnel of the vehicle provided with the shielding according to the invention runs a related risk.

  short circuits or currents.

  The electromagnetic shield according to the invention, according to FIG. 4, is traversed by a projectile 16a, which short-circuits the conductive plates 12 'and 14'. The charge stored in the capacitor 34 is then released to compensation in a time interval extremely short or instant It then flows into the projectile 16 to an extremely high current J, which can be an order of magnitude of 1 to 3 MA The magnetic field B generated by the current J him even in interaction with the current J flowing in the projectile 16a as well as in the conductive plates 12 'and 14', then has the consequence that a force F, the Lorentz force, acts on the projectile 16 a and departs from its original trajectory. Thus, since there is furthermore an angle of inclination α between the flight direction of the projectile 16 a and the electromagnetic shielding according to the invention, there is also a moment of rotation Q on the

projectile 16 a.

  The forces which appear, and which act on the projectile 16 a, can spread the projectile 16

has from its initial flight direction.

  FIG. 5 represents the ballistic situation according to FIG. 4, a moment later the projectile 16a is deviated from its initial trajectory by the shearing forces that appear, and it is possible that it is inclined and broken. The effect of the projectile 16 a is strongly attenuated, so that the damage on the main armor 30 in a zone 31 is relatively

  unimportant, whereas without the electronic shielding

  magnetic according to the invention, there would have been perforation

the main shield 30.

  If the charge jets digs the smaller ones can actually be sprayed by the device according to the invention, the charge jets digs the largest, which require too much energy for their thermal spraying, however are deflected and / or broken of the As described above, the electromagnetic shielding according to the invention is thus for the first time in the position of deflecting and / or breaking the projectiles-arrows up to the largest calibers and

  to remove from them their dangerous effect.

  As soon as a projectile has been made harmless in the manner described above, the capacitor 34 having been discharged, this capacitor 34 is recharged by means of a device (not shown), for example a voltage generator, a transformer or batteries. connected accordingly if

  the projectile did not permanently put in

  circuit shielding according to the invention.

  In order to prevent the electromagnetic shielding according to the invention, applied to a vehicle, from being totally paralyzed by a single projectile, it is possible to

  separate into small sections the electronic shielding

  If a section is short-circuited by a projectile, the section in question can be separated from the remaining sections still intact, so that the electromagnetic shielding according to the invention is again in working order for the remaining main part

of the vehicle to be protected.

  There is also the question of a multiple device of conductive plates 12 'and 14' and insulating plates 24 and 28, in order to repeatedly deflect

  projectiles of larger caliber.

Claims (14)

  1 Electro-magnetic shielding, in particular against metallic projectiles, preferably arrow projectiles, hollow charge jets, and similar devices, with at least two plates of conductive material (conductive plates) arranged one behind the other in relation to the direction of flight of the projectile and at a distance from the other, at least one of the plates being brought to an electric potential, characterized in that at least one capacitor (34) is connected in parallel with at least two plates conductive (12 ', 14').   Shield according to Claim 1, characterized in that the capacitance of the conductive plates (12 ', 14') is smaller than the capacitance of the corresponding capacitor (34) or capacitors. corresponding (34).   3 Shield according to one of claims 1 or   2, characterized in that at least one of the plates (12 ', 14'), in particular the first plate (12 ') in the   the flight direction (32) of the projectile is grounded (36).   4 Shield according to one of claims 1 to   3, characterized in that the capacitance of the two conductive plates (12 ', 14') is preferably in a factor of at least 50, and in particular at least 100, smaller than the capacitance of the capacitor (34) or some capacitors (34).   Shield according to one of Claims 1 to   4, characterized in that the conductive plates or plates (12 ', 14') each have a thickness of at least   minus 2 mm, preferably between 3 and 5 mm.   Shielding according to one of claims 1 to   , characterized in that between the conductive plates (12 ', 14') are insulating plates (24),   preferably of dielectric material.   Shielding according to Claim 6, characterized in that the insulating plate (24) is a plastic plate, in particular made of polyethylene, hard PVC, pertinax, fiberglass-reinforced plastic, or the like.   8 Shield according to one of claims 6 or   7, characterized in that the insulating plate (24) is bonded by collages (26a, 26b) with the plates or plates conductive (12 ', 14').   9 Shield according to one of claims 1 to   8, characterized in that one of the sides of the electromagnetic shield (10) is fixed on an object to be protected, in particular a vehicle.   Shield according to claim 9, characterized in that between the electromagnetic shielding (10) and the object to be protected is placed a bonding material, which is preferably constituted by a plate (28) of insulating material, for example a material   fiberglass reinforced plastic (GFK).   11 Shield according to one of claims I to   characterized in that the electromagnetic shield (10) is attached to the object such that the electromagnetic shield has an angle of inclination (a)   relative to the direction of flight (32) of the projectile.   12 Shield according to one of claims 1 to   11, characterized in that, in the flight direction of the projectile and behind the electromagnetic shield, is placed a main shield (30) of the object, in particular of the vehicle.   13 Shield according to one of claims 1 to   12, characterized in that the electromagnetic shield (10) is placed or secured with clearance on the shield   principal (30) of the object to be protected.   Shield according to one of Claims 1 to   13, characterized in that the conductive plate (12 ') foremost with respect to the flight direction (32) of the projectile is bonded with a suitable clearance, for example   by means of springs, together with the rest of the electro- magnetic (10).   Shield according to one of Claims 1 to   14, characterized in that the electromagnetic shield (10) is divided into a large number of separate sections   electrically and preferably mechanically.   16 Shield according to one of claims 1 to   characterized in that a device for   charging the capacitor (s) (34).   17 Shield according to one of claims 1 to   16, characterized in that two or more are provided superimposed shields.