WO2006085989A2

WO2006085989A2 - Explosively powered electromagnetic reactive armor

Info

Publication number: WO2006085989A2
Application number: PCT/US2005/024776
Authority: WO
Inventors: Alan J. Garvey; David B. Novotney; John A. Graham
Original assignee: Ensign-Bickford Aerospace & Defense Company
Priority date: 2004-07-16
Filing date: 2005-07-13
Publication date: 2006-08-17
Also published as: WO2006085989A3

Abstract

Explosively powered electromagnetic reactive armor comprises one or more modules (32) mounted on a base armor (52). The modules (32) comprise one or more generator units (50) including a steel armor plate (36) which covers the module (32) and receives the impact from a shaped charge projectile (60). The impact of the projectile (60) initiates the explosion of a layer of explosive (40) which activates one or more explosively-activated power sources such as piezoelectric arrays (38, 42) or flux compression generators (156, 158). The activated power sources (38, 42 or 156, 158) generate electric current to generate an electromagnetic field, e.g., by charging a pair of conductive plates (44, 46 or 82, 84). The electrical circuit between the plates is closed by the metal penetrating jet (62, 104) generated from the incoming projectile (60, 102). The resulting electromagnetic field disrupts and disperses the penetrating jet (62, 104) to form a dispersed jet residue (62a, 104a) and thereby protects the base armor (52, 100).

Description

EXPLOSIVELY POWERED ELECTROMAGNETIC REACTIVE ARMOR

BACKGROUND OF THE INVENTION

Field of the Invention

[0001] The present invention is concerned with reactive armor used to protect structures, vehicles, vessels and the like against projectiles. In particular, the present invention is concerned with explosively powered electromagnetic reactive armor.

Related Art

[0002] Combat vehicles have historically employed metal armor to protect themselves against incoming projectiles. Improved anti- armor shaped charges and penetrators have reduced the effectiveness of such armor, and reactive explosive armor was developed to overlie and protect the base armor. The reactive explosive armor provides added protection against proj ectile penetration without the excessive weight penalty associated with simply increasing the thickness of the base armor.

[0003] U.S. Patent 6,758,125, issued to P.A. Zank on July 6, 2004, discloses an active armor system including first and second spaced-apart armor layers having a third layer interposed between the first and second layers. The third layer may be a piezoelectric material, an electrostrictive material, a magnetostrictive material or, generally, "any material capable of producing an electrical or magnetic field within the space in response to the application of mechanical force on this third layer". (See the Abstract.) The mechanical impact of a missile 15 is used to generate an electric current via a solid state power converter 36, to generate a disruptive electrical or magnetic field which serves to disrupt the gas jet of an incoming mis- sile 15 (column 3, lines 4-18). Column 3, line 19 to column 4, line 9, describes embodiments which use as the third layer a piezoelectric material layer, e.g., layer 48 in Figure 3 or plate 70 in Figure 4.

[0004] Japanese Patent Publication JP-03067999-A to Kobayashi and published in 1991 discloses a reactive armor structure comprising two metal foils (3) separated by an insulating material (1) and disposed between two armor plates (4), (5) positioned to protect a main armor plate (8). A large capacity, high voltage capacitor (2) electrically connected to metal foils (3) discharges into the foils when the circuit is closed by penetration of an armor- piercing missile (6). A plasma (11) is generated from foils (3) by the large current flowing through them and the resulting pressure moves the armor plates (4), (5) in a direction oblique to the path of the missile, thus breaking up the missile (6) into pieces (15), as shown, e.g., in Part (III) of Figure 2. [0005] U.S. Patent 4,368,660, issued January 18, 1983 to M. Held, discloses a multi-layer arrangement of reactive armor in which an explosive layer 3 is sandwiched between an inert front wall 2 and an inert rear wall 4. When struck at an angle by a shaped charge projectile 5, the explosive layer 3 detonates, and the inert walls 2 and 4, which may be made of high- density metal, are respectively moved by the explosive force in opposite directions substan- tially perpendicularly to the surface of explosive layer 3. hi this way, walls 2 and 4 traverse the travel path of the penetrating jet 13 to break up and consume the jet. [0006] Various developments in the field of reactive explosive armor are exemplified by the following U.S. Patents: 4,741,244; 4,867,077; 4,881,448; 4,981,067; 5,012,721; 5,070,764; 5,293,806; 5,413,027; 5,637,824; 5,922,986; 6,021,703; and 6,474,213. The sys- terns disclosed in the above-noted patents generally rely on sandwiched layers of explosive material and metal plates reacting to the incoming projectile by causing a separation of the metal plates to disrupt the shaped charge round or penetrator. The base armor protected by the reactive armor is impinged upon by the disrupted fragments after the reactive armor has defeated at least some of the kinetic and thermal energy of the incoming round. [0007] As modern penetrators have increased in capability, the amount of energy and the concomitant amount of explosive required to defeat the incoming round has increased, thereby increasing explosive hazards to both friendly personnel in the vicinity of the reactive armor and the protected vehicle or structure itself. In addition, conventional explosive reactive armor decreases in effectiveness the closer the penetration angle of the incoming projec- tile approaches orthogonality, hi that regard, note that the effectiveness of the arrangement described above in connection with U.S. Patent 4,368,660 increases as the angle of impact of the projectile deviates from the orthogonal.

[0008] A press release dated 01-07-02 from Defence Science & Technology Laboratory ("DSTL"), a Ministry of Defence research laboratory in the United Kingdom, disclosed the concept of electric reactive armor on the DSTL website, 'www.dstl.gov.uk.' The system is described as comprising an outer skin of metal plates which can be rapidly electrified to several thousand volts when in danger of being hit by a shaped charge warhead. The molten copper jet of the warhead penetrates the electrified layers and is subjected to many thousands of amperes of current flow. The resulting high temperatures and powerful magnetic fields are said to almost instantaneously disperse the molten copper jet.

[0009] It is believed that as presently constituted, known electric reactive armor schemes require a high- voltage power supply to provide power to the panels, and high-voltage/liigh- capacity capacitors to store the energy generated. In the case of application to an armored vehicle, as the power supply is inside the vehicle, the shell of the armored vehicle must be breached to allow cabling to connect the power supply to the electric armor panels. The known systems must be pre-armed in anticipation of an attack, by electrifying the outer skin of metal plates. Further, this type of electric reactive armor may not be able to handle multiple incoming rounds very well, because of the time necessary to recharge the capacitor banks. Individual panels of this type of electric reactive armor also have to connect to a power bus and are subject to failure if the power bus or power source become damaged. Finally, the panels of such a system are not independent and modular, as they require hookup to a power bus.

SUMMARY OF THE INVENTION

[0010] Generally, the present invention provides a modular, explosively powered, electromagnetic reactive armor system for protecting structures, vessels and vehicles, such as tanks and armored personnel carriers, from penetration by projectiles, such as kinetic energy or shaped charge projectiles. Protection is attained by employing an explosively-activated power source in the reactive armor system to generate an electromagnetic field which disrupts the shaped charge. [0011] Specifically, in accordance with the present invention there is provided a reactive armor assembly for attenuating the penetration power of a projectile, such as the penetrating jet of a shaped charge projectile. The assembly comprises a structure defining a dispersal zone, an explosive charge carried by the structure and configured to be detonated by such projectile, e.g., a shaped charge, acting on the assembly, and an explosively-activated power source. The explosively-activated power source is disposed sufficiently close to the explo- sive charge to be activated by detonation of the explosive charge to generate in the dispersal zone an electromagnetic field of sufficient intensity to attenuate the penetrating power of the projectile, e.g., of a shaped charge penetrating jet. [0012] In one aspect of the invention, the assembly further comprises electrical conductors connecting the power source to a pair of electrically conductive members which are spaced apart and electrically isolated from each other to define therebetween a field zone which comprises at least a part of the dispersal zone. An electromagnetic field of sufficient intensity to attenuate the penetrating power of the shaped charge penetrating jet is generated when the electrically conductive members are electrically charged by the explosively- activated power source and a shaped charge penetrating jet penetrates and electrically connects the pair of charged electrically conductive members. [0013] Another aspect of the invention provides for the structure to comprise sidewalls closed by a protective plate, e.g., a protective armor plate, to define a modular structure within which is contained the explosive charge, the explosively-activated power source and the dispersal zone, with the explosively-activated power source disposed adjacent to the explosive charge and between the explosive charge and the dispersal zone. [0014] Other aspects of the invention provide one or more of the following features, alone or in suitable combinations. The structure may have an impact side and a base side, the dispersal zone may be located at or adjacent to the base side, and the explosive charge may be carried between the impact side and the dispersal zone; the explosively-activated power source may be selected from the group consisting of one or both of a piezoelectric crystal array and an explosively-pumped flux compression generator; when the explosively-activated power source comprises an explosively-pumped flux compression generator, the assembly may further comprise (1) a start current piezoelectric crystal array which is electrically connected to the explosively-pumped flux compression generator whereby, upon activation of the start current piezoelectric array, a start current is supplied to the explosively-pumped flux compression generator, or (2) electrical leads connecting the explosively-pumped flux com- pression generator to an extraneous source of electrical power to supply a start current to the flux compression generator.

[0015] A particular aspect of the present invention provides a reactive armor assembly for attenuating the penetration power of a shaped charge and comprising the following components: a structure having an impact side defined by an armor plate, and sidewalls joined at one end to the armor plate and having an opposite end defining a base side of the structure, an explosive layer disposed within the structure and configured to be detonated by a shaped charge penetrating the armor plate, an explosively-activated power source disposed within the structure at or adjacent to the explosive layer, electrical leads connecting the power source to a pair of electrically-conductive plates spaced apart from each other to define therebetween a field zone, the structure further defining a spacer zone adjacent the base end of the structure, the field zone and the spacer zone cooperating to define a dispersal zone, the assembly being so constructed that detonation of the explosive layer by impact of the shaped charge activates the power source and generates within the field zone an electromagnetic field of sufficient intensity to attenuate penetration power of the shaped charge in the dispersal zone. [0016] Another particular aspect of the present invention provides a reactive armor assembly for attenuating the penetration power of a shaped charge and comprises the following components. A structure has sidewalls and an impact side defined by an armor plate, the armor plate having an outer surface and an inner surface, and the sidewalls respectively having one end which is joined to the armor plate and having an opposite end defining a base side of the structure. A pair of electrically-conductive members is disposed within the structure, the members being spaced apart from each other to define therebetween a field zone. The struc- ture further defines a spacer zone adjacent the base end of the structure, the field zone and the spacer zone cooperating to together define a dispersal zone within the structure at the base end thereof. A first explosively-activated power source ("first EAPS") is disposed within the structure at or adjacent to the inner surface of the armor plate, and an explosive charge is disposed within the structure. First electrical conductors operatively connect the first EAPS with one or more detonators disposed in explosive signal-transfer relationship to the explosive charge. A second explosively-activated power source ("second EAPS") is disposed within the structure between the first EAPS and the electrically-conductive members and is sufficiently close to the explosive charge so that detonation of the explosive charge activates the second EAPS to generate an electric current. Second electrical conductors operatively connect the second EAPS to the electrically conductive members. The assembly is constructed so that upon activation of the first EAPS by the action of a shaped charge thereon, an electrical signal is generated and transmitted via the first electrical conductors to the one or more detonators to initiate the detonators and thereby detonate the explosive charge. Detonation of the explosive charge activates the second EAPS to generate therefrom within the field zone an electromagnetic field of sufficient intensity to attenuate penetration of the shaped charge through the dispersal zone. [0017] Other aspects of the present invention are described in the following description and shown in the appended drawings. Reference herein and in the claims to the action or effect of a projectile or shaped charge, includes the action or effect of the penetrating jet generated by a shaped charge.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic cross-sectional view of a prior art electric reactive armor; [0019] Figure 2 is a schematic cross-sectional view of an explosively powered electromagnetic reactive armor module in accordance with one embodiment of the present inven- tion;

[0020] Figure 2 A is a partial schematic cross-sectional view of a variation of the embodiment of Figure 2 in which shock-absorbent layers are part of the structure; [0021] Figure 3 is a schematic cross-sectional view of an explosively powered electromagnetic reactive armor module in accordance with a second embodiment of the present in- vention;

[0022] Figure 4 is a schematic exploded view of a piezoelectric stack usable as a component of the reactive armor assemblies of the present invention;

[0023] Figure 5 is a plan view of an array of piezoelectric stacks usable as a component of the reactive armor assemblies of the present invention; [0024] Figure 5 A is a cross-sectional view taken along line A-A of Figure 5;

[0025] Figure 6 is a schematic cross-sectional view of an explosively-activated flux compression generator usable as a component of the reactive armor assemblies of the present invention; [0026] Figures 6A-6C are schematic cross-sectional views, reduced in size relative to Figure 6, showing various stages of the functioning of the explosively-activated flux compression generator of Figure 6;

[0027] Figure 7 is a schematic cross-sectional view of an explosively powered reactive armor module in accordance with a third embodiment of the present invention; [0028] Figure 8 is a schematic cross-sectional view of an explosively powered reactive armor module in accordance with a fourth embodiment of the present invention; and [0029] Figure 8 A is an enlarged portion of Figure 8. DETAILED DESCRIPTION OF THE INVENTION AND SPECIFIC EMBODIMENTS THEREOF

[0030] The schematic drawing of Figure 1 shows a prior art electric reactive armor module 12 which is powered by a vehicle electric power supply (not shown). Module 12 is mounted on the exterior surface 10a of a base armor 10, which may comprise part of the hull of a tank or other armored vehicle. Module 12 is comprised of sidewalls 14 which are made of any suitable metal, such as steel, and are secured to exterior surface 10a of base armor 10. An outer plate 16, which may also be made of steel, is electrically grounded and separated by a space 18 from an insulated inner plate 20. Inner plate 20 is also mounted on sidewalls 14, and is spaced from exterior surface 10a of base armor 10 to define between inner plate 20 and surface 10a a space or air gap 22.

[0031] A capacitor 24 is electrically connected by electrical connectors (not shown) through a breach (not shown) in the vehicle's hull, to the electrical power supply of the vehicle. The electric reactive armor is thus operated by the armored vehicle's regular electrical power supply or an auxiliary power supply. Output electrical leads 26a, 26b are electrically insulated from sidewalls 14 and connect the output of capacitor 24 to, respectively, outer plate 16 and inner plate 20.

[0032] When it is determined that the vehicle is in a dangerous area, a switch is activated, e.g., by the vehicle commander or a crew member, to supply electrical current to the inner plate 20. Should a shaped charge projectile impact module 12 while inner plate 20 is electrically charged, a metal penetrating jet 28 formed upon detonation of the projectile by its impact with outer plate 16 penetrates outer plate 16 and then inner plate 20. The penetrating jet of metal, usually a copper alloy, penetrates both the outer plate 16 and the inner plate 20. This makes an electrical connection between plates 16 and 20 and electrical leads 26a, 26b supply thousands of amps of electricity from capacitor 24 to vaporize most of the molten copper jet 28 to form a dispersed jet residue 30. The dispersed jet residue 30 impacts harmlessly, or at least with greatly diminished force, against the base armor 10 of the vehicle's hull. Despite the high electrical charge, the electrical load on the vehicle's battery is said not to be excessive and to be comparable to that imposed by cold temperature start-up of the en- gine.

[0033] The following description of Figures 2 and 3 refers particularly to explosively powered electromagnetic reactive armor for armored vehicles, but it is to be understood that the explosively powered electromagnetic reactive armor of the described embodiments could as well be applied to any type of vehicle, vessel or structure.

[0034] Referring now to Figure 2, there is shown an electromagnetic reactive armor module 32 in accordance with one embodiment of the present invention, which employs a piezoelectric crystal array as an explosively-activated power source. (Other embodiments of the invention may use other explosively-activated power sources, for example, an explosively-activated flux compression generator, as described below in connection with the description of Figures 6-8, or a combination of one or more piezoelectric crystal arrays and one or more explosively-activated flux compression generators.) The reactive armor module 32 comprises sidewalls 34 which may define in plan view a rectangular, or other polygonal, or curvilinear shape of the module. Any shape suited to a particular need may be employed. A protective plate is provided in the illustrated embodiment by an armor plate 36 which is mounted on sidewalls 34 and serves to close the module to provide an enclosed explosively powered electromagnetic reactive armor module 32 mounted on exterior surface 52a of a base armor 52. Armor plate 36 is advantageously designed to protect the interior of module 32 from small arms fire, shrapnel and the like. Typically, to attain this objective, armor plate 36 may comprise any suitable material, for example, a hardened steel armor plate of at least 7 or 8 millimeters thickness which covers module 32 and defines its impact surface. Mounted within the module 32 and immediately beneath and in abutting contact with armor plate 36 is a first piezoelectric array 38. A high-explosive layer 40, for example, a layer of PETN or RDX-based PBX, is sandwiched between first piezoelectric array 38 and a second piezoelectric array 42. A first conductive plate 44 is mounted in contact with second piezoelectric array 42 and a second conductive plate 46 is mounted within module 32 and is spaced apart and electrically isolated from first conductive plate 44 to define therebetween a field zone 48. Space 48 may optionally be filled with a dielectric material, not shown in Figure 2. Each of the armor plate 36, the piezoelectric arrays 38, 42, the high-explosive layer 40 and the conductive plates 44, 46 (which may be collectively referred to as a generator unit 50) are substantially co-extensive with each other. Electrical connectors 58 a, 58b disposed within module 32 connect the first and second piezoelectric arrays 38, 42 to conductive plates 44, 46. [0035] Module 32 is affixed by any suitable means such as mechanical fasteners, welding or the like, to base armor 52, which may comprise a portion of the hull of a tank or other armored vehicle, a vessel, a fortification or other structure, or the like. Module 32 includes spacers 54 which support generator unit 50 spaced from the exterior surface 52a of base armor 52 to define an air gap 56 between second conductive plate 46 and exterior surface 52a. [0036] In use, a metal penetrating jet 62, typically copper or a copper alloy, is generated by a shaped charge projectile 60, shown broken away and in dash outline in Figure 2, impact- ing upon hardened armor plate 36. The shaped charge projectile 60 generates in the known manner the metal penetrating jet 62. The impact penetration of the penetrating jet 62 detonates the explosive layer, thereby compressing the entire major surface of piezoelectric arrays 38, 42. The compressed piezoelectric arrays 38, 42 generate a large electrical potential between conductive plates 44, 46. As the metal of penetrating jet 62 (or a different metal pro- jectile, such as a kinetic energy round) bridges charged plates 44, 46, an electrical circuit is closed, generating a strong electromagnetic field and subjecting the penetrating jet to intensive ohmic heating. The combined effect of the magnetic field and ohmic heating disrupts and breaks up penetrating jet 62 into a dispersed residue of metal, schematically indicated at 62a. Current flow through the penetrating jet 62 will usually be sufficient to cause a phase change, including vaporizing at least a portion of the penetrating jet 62. The dispersed residue 62a impacts harmlessly, or at least with greatly diminished force as compared to penetrating jet 62, against the base armor 52.

[0037] It is seen that the electrical power necessary to defeat the shaped charge penetrating jet 62 is generated in the module 32 itself and entirely externally of the hull of the vehicle (base armor 52). Consequently, there is no need to provide an external source of electrical energy, for example, there is no need to breach the hull in order to provide an electrical connection from the vehicle's internal power system to the electric reactive armor. Electrical power is generated from the impact and detonation of the explosive coupons and subsequent compression of the piezoelectric arrays, (hi only some embodiments of the present invention, as described below, an external source of electrical power may be employed.)

[0038] Effectiveness of the reactive armor system of the present invention, regardless of the type of explosively-activated power source employed, is independent of the angle at which the projectile 60 impacts the armor plate 36 of module 32. In the illustrated embodiment, the impact is shown as orthogonal to armor plate 36 of module 32, but it will be appre- ciated that the operation of module 32 will be initiated regardless of the angle of impact of projectile 60 onto armor plate 36. [0039] It will further be appreciated that each module is self-actuating, i.e., each module responds to impact of a projectile and does not require arming or any other preparation in advance of an attack. This provides the great advantage that the reactive armor of the present invention is at all times in a ready or armed state and therefore able to respond without arm- ing or other intervention to an unsuspected attack. Additionally, the present invention uses substantially less explosive material, when compared to current non-electric reactive armor systems, to initiate the reactive armor system to disrupt and defeat the impacting incoming shaped charge projectile. The present invention provides personnel in the area at least as much safety as offered by prior art electromagnetic armor systems. [0040] Any desired number of modules such as module 32 can be placed side by side to cover any desired portions, or the entirety, of the vehicle hull or other structure provided by base armor 52. Each module is independent of any other similar or identical modules and will act independently of each of such other modules and requires no external electrical power supply. Generally, the present invention contemplates the provision of independent modules of the explosively powered electromagnetic reactive armor to be mounted on the base armor or other surface to be protected.

[0041] The embodiment of Figure 2 illustrates the efficacy of reactive armor module 32 in defeating a shaped charge which generates a penetrating jet. However, the reactive armor assemblies of the present invention are effective against projectiles generally, such as, for ex- ample, kinetic energy projectiles made of hardened metal, depleted uranium or the like. It is believed that in such cases power levels which are significantly higher than those required to defeat the penetrating jet of a shaped charge will be required. The size of a reactive armor assembly of the present invention, including the size and number of explosively- activated power sources used in any one module, will bear a relation to the power levels which can be generated. Reactive armor assemblies of the present invention can be sized according to the planned use. Thus, reactive armor assemblies destined for use on large structures such as bunkers, ships and the like can generally be made larger and more powerful than those destined for use on smaller structures, such as tanks, armored personnel carriers or other vehicles. [0042] Figure 2A illustrates a variation of the embodiment of Figure 2 wherein shock- absorbing layers are included in the structure. Elements of Figure 2 A which are identical to those of Figure 2 are identically numbered and serve the same purpose as they do in Figure 2. Therefore, the structure and function of such elements is not repeated in connection with the description of Figure 2A. The embodiment of Figure 2 A differs from the embodiment of Figure 2 only in that a first shock-absorbing layer 41 is interposed between high explosive layer 40 and second segmented piezoelectric array 42, and a second shock-absorbing layer 43 is interposed between second piezoelectric array 42 and first conductive plate 44. First and second shock-absorbing layers 41, 43 may be made of any suitable material such as fiber, rubber or a polymeric material, or a combination of such, in order both to attenuate the impact of high explosive layer 40 on second piezoelectric array 42 and to reduce the effect of vibration thereon, e.g., vibration caused by travel of a vehicle on which module 32 is mounted. Additional shock-absorbing layers (not shown) may be included in the structure, for example, between armor plate 36 and first piezoelectric array 38 and between first piezoelectric array 38 and high explosive layer 40.

[0043] Figure 3 shows another embodiment of the present invention comprising a reactive armor module 64 comprised of sidewalls 70 and closed by a hardened steel armor plate 66. Module 64 may be in its outward configuration identical to or similar to module 32 of Figure 2, including the various plan view configurations described in connection with the description of Figure 2. In the embodiment illustrated in Figure 3, the underside of armor plate 66 overlies a first (leading) piezoelectric array 68 which may be substantially coextensive with armor plate 66. Armor plate 66 and first piezoelectric array 68 together comprise a lead- ing generator unit 72. A trailing generator unit 74 is comprised of a second (intermediate) piezoelectric array 76, a third (trailing) piezoelectric array 80 and, sandwiched between them, an explosive layer 78. Trailing generator unit 74 overlies and abuts a first conductive plate 82 which is spaced apart and electrically isolated from a second conductive plate 84 to define therebetween a field zone 86. Trailing generator unit 74 need not necessarily abut first con- ductive plate 82, but may be spaced therefrom. Armor plate 66, first piezoelectric array 68, second piezoelectric array 76, explosive layer 78, third piezoelectric array 80, first conductive plate 82 and second conductive plate 84, may all be substantially coextensive with each other. [0044] Detonators 88a, 88b are embedded within explosive layer 78 and electrically connected, respectively, by first electric connectors 90a, 90b to first piezoelectric array 68. Sec- ond electric connector 92a connects first conductive plate 82 to be energized by the electrical output of the second piezoelectric array 76. Similarly, second electrical connector 92b connects second conductive plate 84 to be energized by the electrical output of third piezoelectric array 80. Spacers 96 support the leading generator unit 72 and the trailing generator unit 74 above the surface 100a of base armor 100, so as to provide an air gap 98 between second conductive plate 84 and the exterior surface 100a of base armor 100. Base armor 100 may comprise the hull of an armored vehicle or be part of some other structure to be protected by module 64.

[0045] Module 64 is secured to base armor 100 by being fastened to the exterior surface

100a thereof by any suitable means, e.g., welding, mechanical fasteners, or a combination thereof.

[0046] In operation, when a projectile, such as shaped charge projectile 102, which is shown in Figure 3 broken away and in dash outline, strikes armor plate 66 of module 64, the resulting metal penetrating jet 104 penetrates leading generator unit 72. The impact of projectile 102 compresses first piezoelectric array 68, generating an electric output which detonates instantaneous-acting detonators 88a, 88b, thereby initiating explosive layer 78. Explosive layer 78 in turn compresses second and third piezoelectric arrays 76, 80, generating an output of electrical energy which charges first and second conductive plates 82, 84. Detonation of explosive layer 78 is thus effectuated prior to the time it would be detonated by the impact of projectile 102 or by impingement thereon of its penetrating jet 104. The illustrated arrangement also provides a smooth, even detonation wave across the piezoelectric arrays 76, 80. Explosive layer 78 may thus be initiated by detonators 88a, 88b to generate the electrical charge on conductive plates 82, 84 in advance of the arrival of penetrating jet 104 at or through trailing generator unit 74. This provides more lead time to generate the electric and magnetic field between first and second conductive plates 82, 84 before penetrating jet 104 penetrates first and second conductive plates 82, 84 to establish an electrical connection between them. The resulting electromagnetic field and current flow will serve to disrupt, dis- perse and at least partially vaporize penetrating jet 104 into a dispersed jet residue 104a, shown schematically in Figure 3. The inclusion of one or more detonators to initiate one or more layers of the explosive in response to an incoming projectile reduces the time required to initiate the explosive and thereby improves the system's response to the incoming projectile, e.g., to the penetrating jet of a shaped charge projectile. The dispersed jet residue 104a impacts harmlessly, or at least with greatly diminished force as compared to penetrating jet 104, against base armor 100. [0047] Certain embodiments of the present invention utilize one or more energy storage components, for example, capacitors or inductors, electrically connected to the explosively- activated power source, sometimes herein abbreviated as "EAPS". The energy storage components serve to manage the electrical power generated by the EAPS, e.g., by compression of the piezoelectric crystals by detonation of the explosive coupon. The stored energy is then discharged to create at least part of the surge of electrical power which deflects or disperses at least some of the energy of the incoming projectile. The optional use of energy storage components charged by all or some of the electrical output of the EAPS may be used to manage generation of the electromagnetic field used to defeat the incoming projectile. Such arrange- ment will account for the fact that the EAPS will discharge its electrical power within microseconds of its activation whereas a kinetic energy projectile or the penetrating jet of a shaped charge will enter the field zone only within milliseconds of activation of the EAPS. The electrical storage components are employed to have establishment of the peak electromagnetic field coincide as much as possible with the presence of the projectile or penetrating jet in the field zone, thereby enhancing the effect of the generated electromagnetic field.

[0048] Figure 4 is an exploded schematic view of a typical piezoelectric stack 110 usable in the present invention. The piezoelectric stack 110 is seen to comprise two conductive layers 106a, 106b sandwiched between, respectively, piezoelectric crystals 108a and 108b and piezoelectric crystals 108b and 108c. Typical dimensions A and B of the stack would be about 7.62 cm (3 inches) for dimension A and about 12.7 cm (5 inches) for dimension B.

Any suitable number of layers of alternating conductive layers and piezoelectric crystals may be used. When assembled in a sandwiched layer, conductive layers 106a, 106b, and piezoelectric crystals 108a, 108b and 108c are in abutting contact to comprise the piezoelectric stack 110. The specific dimensions of the stack given above are, of course, merely exem- plary and any suitable dimensions convenient for a particular installation may be employed. [0049] Figures 5 and 5A show a segmented piezoelectric array 112 usable in the present invention and comprised, in the illustrated embodiment, of six piezoelectric crystals HOa, 110b, 110c, HOd, 11Oe and HOf. In the cross-sectional view of Figure 5 A, there are shown three conductive layers, 106a, 106b and 106c and four layers, 108 a, 108b, 108c and 108d of piezoelectric crystals. The particular number and arrangement of diodes 11 Oa- 11 Of in the illustrated embodiment are, of course, exemplary only and any suitable number and arrangement may be employed as is convenient in a given case. Individual piezoelectric crystals 11 Oa through 11 Of are separated from each other by dividers 113 which may be made of any suitable material which conducts electricity in one direction only. For example, dividers 113 may comprise a semiconductor material, a rectifier or a diode. Isolation of the piezoelectric crystals from each other serves to prevent disruption of the entire array of crystals from acci- dental damage to individual ones of the piezoelectric crystals in the array. Such damage may occur, for example, from vehicle vibration or single-point impact from small arms fire. [0050] As noted above, explosively-activated power sources other than piezoelectric crystal arrays may be employed in the practices of the present invention. For example, one or more flux compression generators, sometimes herein abbreviated "FCG" may be employed as the explosively-activated power source. Figure 6 shows an explosively activated coaxial flux compression generator 114 which is of generally cylindrical configuration. Explosively- activated FCGs utilize a high explosive to rapidly compress an existing magnetic field, transferring much of the explosive energy into the magnetic field. The magnetic field must be produced in the FCG by a start current prior to initiation of the FCG high explosive. In ac- cordance with an aspect of the present invention, the starter electric current could be supplied from an external source, such as the electrical system of a vehicle protected by the reactive armor of the invention. However, the present invention also advantageously provides for generating the start current in response to the impact of an incoming shaped charge (or other round). While FCGs may have different geometrical configurations, the most commonly used arrangement, and one which is well suited for the practices of the present invention, is a coaxial FCG which provides a substantially cylindrical assembly which is compact and small relative to the amount of power it generates.

[0051] Flux compression generator ("FCG") 114 is comprised of a copper armature tube 116 which contains a high explosive 118, such as a plastic-bonded PETN, having an input end 118a. Armature tube 116 is supported at each of its ends by insulator blocks 120, 122 within a dielectric structural jacket 124. Armature tube 116 is spaced from the interior of jacket 124 to leave an annular-shaped space 126 between armature tube 116 and jacket 124. [0052] A continuous helical stator coil 128 of heavy, electrically-conductive wire, e.g., copper wire, extends along most of the length of dielectric structural jacket 124. In some ver- sions of the FCG, the stator coil may be split into longitudinal segments, with the wire bifurcating at the boundaries of the segments, to optimize the electric inductance of the stator coil. [0053] A stator input ring 130 is connected to the input end 128a of stator coil 128 and a stator output ring 132 is connected to the output end 128b of stator coil 128. Input leads 134a, 134b are connected to stator input ring 130 and output leads 136a, 136b are connected to stator output ring 132. [0054] In use, a start current is delivered from a source of electric power (not shown in Figure 6) through input leads 134a, 134b into stator coil 128 to flow through coil 128 and create a magnetic flux field around it. High explosive 118 is then detonated by any suitable means, e.g., by a detonator (not shown in Figure 6) at input end 118a of explosive 118. [0055] Figures 6A, 6B and 6C show several stages of the functioning of FCG 114. Once the high explosive 118 is initiated at its input end 118a, the explosive front propagates through the explosive in the direction indicated in each of Figures 6A, 6B and 6C by an arrow (unnumbered), distorting the armature tube into a conical shape (typically 12 to 14 degrees of arc). Where the armature tube 116 has expanded to the full diameter of the stator coil 128, it forms a short circuit between the ends of the stator coil 128, shorting and thus isolating the start current source and trapping the current within the coil 128 of the FCG. The propagating short has the effect of compressing the magnetic field, while reducing the inductance of the stator coil 128. The result is that devices such as FCG 114 will produce a ramping current pulse, which peaks before the final disintegration of the device. Published results suggest ramp times of tens to hundreds of microseconds, specific to the characteristics of the device, for peak currents of tens of MegaAmperes and peak energies of tens of MegaJoules. The current multiplication (i.e., ratio of output current to start current) achieved varies with designs, but multiples as high as 60 have been demonstrated. In order that the intense magnetic forces produced during the operation of the FCG 114 not cause the device to disintegrate prematurely, the dielectric structural jacket 124 is made of a non-magnetic and suitably structurally strong material. Materials such as concrete or fiberglass in an epoxy matrix have been used. In principle, any material with suitable electrical and mechanical properties could be used, for example, a glass or Kevlar epoxy composite has suitable properties and is lighter per unit volume than many other suitable materials. Devices such as FCG 114, even when configured to be small enough to be readily accommodated in the reactive armor assemblies of the pre- sent invention, are capable of producing electrical energies of tens of MegaJoules in tens to hundreds of microseconds, and peak power levels on the order of TeraWatts to tens of Ter- aWatts are available from one-shot FCGs. The structure of devices such as FCG 114 is well known in the art; these known FCG devices find use as an explosively-activated power source in the practices of the present invention.

[0056] Figure 7 shows another embodiment of the present invention comprising a reactive armor module 138 comprised of sidewalls 140 and spacers 141 and closed by a hardened steel plate, e.g., steel armor plate 142. Module 138 may in its outward configuration be identical to or similar to modules 32 and 64 described above in connection with Figures 2 and 3. In this embodiment, the underside of armor plate 142 abuts a high explosive layer 144 which is sandwiched between armor plate 142 and a first conductive plate 146. A second conductive plate 148 is spaced from first conductive plate 146 to define therebetween a field zone 150. A spacer zone 152 is defined between second conductive plate 148 and the outer surface 154a of hull 154 to which reactive armor module 138 is affixed by any suitable means. Field zone 150 and spacer zone 152 cooperate to define a dispersal zone 153. [0057] A first FCG 156 and a second FCG 158 are disposed within field zone 150 with their respective inlet ends 156c, 158c, penetrating through openings (unnumbered) in first conductive plate 146 and high explosive layer 144, so that inlet ends 156c, 158c are embedded within high explosive layer 144. Two FCGs are used to provide redundant power sources in case one should fail. Start current electrical leads 156a, 156b serve to conduct a start current from an extraneous source of electricity to first FCG 156. Similarly, start current electrical leads 158a, 158b connect a start current from the same or a different extraneous source of electricity to second FCG 158. Start current electrical leads 156a, 156b and 158a, 158b may, for example, be connected to the electrical system of the vehicle of which hull 154 is a part. Because the start current required is quite small, electrical leads 156a, 156b and 158a, 158b may advantageously provide a continuous start current through the stator coil (not shown in Figure 7) of FCGs 156 and 158 in order to avoid the necessity of having to antici- pate an attack and arm the device by supplying the start current only during periods of perceived danger. By supplying the small start current on a continuous basis, reactive armor module 138 is able to function upon the impact of a shaped charge, without need for a pre- attack arming of the device. Alternatively, a switch may be installed to enable the start current to be turned on and off, e.g., to conserve electrical power while a vehicle on which the reactive armor module is mounted is in a safe area. [0058] Field electrical leads shown generally at 160a, 160b and 162a, 162b connect the power output of FCGs 156, 158 to, respectively, first conductive plate 146 and second conductive plate 148.

[0059] ha use, the metal penetrating jet 164 of a shaped charge 166 penetrates armor plate 142 and initiates high explosive 144. As FCGs 156 and 158 supplied with a start current, either continuously or by arming the device in anticipation of an attack, detonation of high explosive layer 144 functions FCGs 156 and 158 as described above with reference to Figures 6-6C. The resulting electromagnetic surge creates an extremely intense electromagnetic field within field zone 150 and this field disrupts penetrating jet 164 as it penetrates into field 150, breaking up the penetrating j et to form a dispersed j et residue 164a as schematically shown in Figure 7, thereby attenuating the energy of penetrating jet 164 prior to its making contact with hull 154.

[0060] Referring now to Figures 8 and 8 A, there is shown another embodiment of the present invention which utilizes FCGs and in which the start current supplied by reactive ar- mor module 168 itself, so that an extraneous source of electrical energy is not required. The configuration of reactive armor module 168 is similar in many structural respects to the embodiment of Figure 7 and therefore a detailed description will not be repeated. The components of reactive armor module 168 corresponding to those of Figure 7 are identically numbered except for the addition of a prime indicator. Thus, reactive armor module 168 is essen- tially comprised of sidewalls 140', spacers 141', a hardened steel armor plate 142' which cooperates with sidewalls 140' to define a reactive armor module 168 within which is contained the components described below. As in the Figure 7 embodiment, field zone 150' and spacer zone 152' cooperate to define dispersal zone 153'. [0061] In this embodiment, the start current electrical leads 156a, 156b and 158a, 158b of the Figure 7 embodiment are omitted and the source of start current is provided by a piezoelectric start current crystal array 170. Piezoelectric start current crystal array 170 is sandwiched between high explosive layer 144' and first conductive plate 146'. It will be noted that, as in the Figure 7 embodiment, FCGs 156' and 158' penetrate through suitable openings in first conductive plate 146' and similarly through suitable openings in piezoelectric start current crystal array 170 so that their input ends 156c' and 158c' (corresponding to input ends 118a illustrated in Figure 6) abut or slightly penetrate into high explosive layer 144'. As best seen in Figure 8A, start current electrical leads 172 and 176 connect the output of piezoelec- tric start current crystal array 170 to the stator coil (not shown in Figures 8 or 8 A but corresponding to stator coil 128 of Figure 6) of FCG 156'. Similarly to the start current electrical leads of FCG 156', start current electrical leads 174 and 178 connect the output of piezoelectric start current crystal array 170 to the stator coil of FCG 158'. Field electrical current leads 180a, 180b connect the output of FCG 156' across first and second conductive plates 146', 148'. Similarly to the field electrical current leads of FCG 156', field electrical current leads 182a, 182b connect the output of FCG 158' across first and second conductive plates 146', 148'. [0062] hi use, penetrating jet 164' of a shaped charge 166' penetrates hardened steel ar- mor plate 142' and detonates high explosive layer 144', thereby crushing the piezoelectric start current crystal array 170 and generating a start current which flows through start current electrical leads 172 and 174 through the stator coils (not shown in Figure 8) of, respectively, FCGs 156' and 158'. High explosive layer 144' then functions the FCGs 156', 158' as described above, creating a powerful electromagnetic field within field zone 150'. Penetrating jet 164' is disrupted by this electromagnetic field which disperses it into the dispersed jet residue 164a' within spacer zone 152', as schematically illustrated.

[0063] It will be appreciated from the foregoing description that the electric reactive armor of the present invention is actuated by impact on it of an incoming projectile and does not require an arming action to be taken in advance of being struck by the incoming projectile (although some embodiments could be so configured). It will further be appreciated that the reactive armor of the present invention does not necessarily require connection to an external source of electrical energy (although some embodiments so provide), but in several embodiments generates electricity by utilizing the kinetic or explosive energy of the incoming projectile to activate a source of electrical power which provides an electromagnetic field to dis- rupt the effect of the incoming proj ectile. Each module of explosively powered electromagnetic reactive armor of the present invention is therefore self-actuating and, in certain embodiments, is independent of external sources of electricity.

[0064] A shock-absorbing layer may be sandwiched between the EAPS and the explosive layer or coupon for a number of reasons, including reduction of vibration shocks on the EAPS and/or the explosive coupon, attenuation of or more even dispersal on the EAPS of the explosive shock energy generated by detonation of the explosive coupon, etc. For example, a shock-absorbing layer may be sandwiched between a piezoelectric crystal array and the explosive layer or coupon.

[0065] Generally, the present invention provides explosively-powered electromagnetic reactive armor equipped with an explosively-activated power source ("EAPS") such as one or more arrays of piezoelectric crystals and/or one or more flux compression generators

("FCG"s) disposed adjacent to an explosive material. For example, the array of piezoelectric crystals or FCGs may be disposed in abutting contact with, or slightly spaced from, an explosive layer, sometimes herein referred to as an "explosive coupon." Upon penetration of the explosive coupon by an incoming projectile, the explosive coupon detonates, thereby activat- ing the EAPS to generate a surge of electricity which deflects or disperses at least some of the kinetic or explosive energy of the incoming projectile. For example, the electrical surge acts to vaporize some or all of the molten metal penetrating jet of a shaped charge projectile before the jet contacts the base armor underlaying the electric reactive armor of the invention. [0066] In the practices of the present invention, a single explosively-activated power source will normally suffice for a given module or assembly, but two or more such explosively-activated power sources are advantageously provided for redundancy, to better assure reliable operation under combat conditions.

[0067] While the invention has been described in detail with respect to specific embodiments thereof, it will be appreciated that the invention may take forms other than those specifically disclosed and illustrated.

Claims

THE CLAIMSWhat is claimed is:

1. A reactive armor assembly for attenuating the penetration power of a projectile, the assembly comprising: a structure defining a dispersal zone; an explosive charge carried by the structure and configured to be detonated by the action of such projectile on the assembly; an explosively-activated power source disposed sufficiently close to the explosive charge to be activated by detonation of the explosive charge to generate in the dispersal zone an electromagnetic field of sufficient intensity to attenuate the penetrating power of the projectile.

2. A reactive armor assembly for attenuating the penetration power of a shaped charge penetrating jet, the assembly comprising: a structure defining a dispersal zone; an explosive charge carried by the structure and configured to be detonated by the action of such shaped charge on the assembly; an explosively-activated power source disposed sufficiently close to the explosive charge to be activated by detonation of the explosive charge to generate in the dispersal zone an electromagnetic field of sufficient intensity to attenuate the penetrating power of the shaped charge penetrating jet.

3. A reactive armor assembly for attenuating the penetration power of a shaped charge penetrating jet, the assembly comprising: a structure defining a dispersal zone; an explosive charge carried by the structure and configured to be detonated by the action of such shaped charge on the assembly; an explosively-activated power source disposed sufficiently close to the explosive charge to be activated by detonation of the explosive charge; electrical conductors connecting the power source to a pair of electrically conductive members which are spaced apart and electrically isolated from each other to define therebetween a field zone which comprises at least part of a dispersal zone, and within which an electromagenetic field of sufficient intensity to attenuate the penetrating power of the shaped charge penetrating jet is generated when the electrically conductive members are electrically charged by the explosively-activated power source and a shaped charge penetrating jet penetrates and electrically connects the pair of charged electrically conductive members.

4. A reactive armor assembly for attenuating the penetration power of a shaped charge penetrating jet, the assembly comprising: a structure comprising sidewalls closed by a protective plate to define a modular structure within which is contained an explosive charge, an explosively-activated power source and a dispersal zone, the explosively-activated power source being disposed adjacent to the explosive charge and between the explosive charge and the disperal zone; the explosive charge being configured to be detonated by the action of such shaped charge on the assembly and the explosively-activated power source being disposed sufficiently close to the explosive charge to be activated by detonation of the explosive charge to generate in the dispersal zone an electromagnetic field of sufficient intensity to attenuate the penetrating power of the shaped charge penetrating jet.

5. The reactive armor assembly of any one of claims 1, 2, 3 or 4 wherein the structure has an impact side and a base side, the dispersal zone is located at or adjacent to the base side, and the explosive charge is carried between the impact side and the dispersal zone.

6. The reactive armor assembly of any one of claims 1 , 2 or 3 wherein the structure further comprises sidewalls and a protective plate closing the sidewalls to define a modular structure having an impact side and an opposite base side, the protective plate defining the impact side of the structure.

7. The reactive armor assembly of any one of claims 1 , 2, 3 or 4 wherein the explosively-activated power source is selected from the group consisting of one or both of a piezoelectric crystal array and an explosively-pumped flux compression generator.

8. The reactive armor assembly of any one of claims 1, 2, 3 or 4 wherein the explosively activated power source comprises at least one piezoelectric crystal array, and at least one shock-absorbing layer abuts the piezoelectric crystal array.

9. The reactive armor assembly of any one of claims 1, 2, 3 or 4 wherein the ex- plosively-activated power source comprises at least one explosively-pumped flux compression generator and the assembly further comprises a start current piezoelectric crystal array which is electrically connected to the explosively-pumped flux compression generator whereby, upon activation of the start current piezoelectric array, a start current is supplied to the explosively-pumped flux compression generator.

10. The reactive armor assembly of any one of claims 1 , 2, 3 or 4 wherein the explosively-activated power source comprises at least one explosively-pumped flux compression generator and the assembly further comprises electrical leads connecting the explosively-pumped flux compression generator to an extraneous source of electrical power to supply a start current to the flux compression generator.

11. A reactive armor assembly for attenuating the penetration power of a shaped charge penetrating jet, the assembly comprising a structure having an impact side defined by a protective plate, and sidewalls joined at one end to the protective plate and having an opposite end defining a base side of the structure; an explosive layer disposed within the structure and configured to be detonated by the action of such shaped charge on the assembly; an explosively-activated power source disposed within the structure at or adjacent to the explosive layer; electrical leads connecting the power source to a pair of electrically- conductive plates spaced apart from each other to define therebetween a field zone; the structure further defining a spacer zone adjacent the base end of the structure, the field zone and the spacer zone cooperating to define a dispersal zone; whereby detonation of the explosive layer by impact of the shaped charge activates the power source and generates within the field zone an electromagnetic field of suffi- cient intensity to attenuate penetration power of the shaped charge penetrating j et in the dispersal zone.

12. A reactive armor assembly for attenuating the penetration power of a shaped charge penetrating jet, the assembly comprising a structure having sidewalls and an impact side defined by a protective plate, the protective plate having an outer surface and an inner surface, the sidewalls respectively having one end which is joined to the protective plate and having an opposite end defining a base side of the structure; a pair of electrically-conductive members disposed within the structure and spaced apart from each other to define therebetween a field zone; the structure further defining a spacer zone adjacent the base end of the structure, the field zone and the spacer zone cooperating to together define a dispersal zone within the structure at the base end thereof; a first explosively-activated power source ("first EAPS") disposed within the structure at or adjacent to the inner surface of the protective plate; an explosive charge disposed within the structure; first electrical conductors operatively connecting the first EAPS with one or more detonators disposed in explosive signal-transfer relationship to the explosive charge; a second explosively-activated power source ("second EAPS") disposed within the structure between the first EAPS and the electrically-conductive members and sufficiently close to the explosive charge whereby detonation of the explosive charge activates the second EAPS to generate an electric current; second electrical conductors operatively connecting the second EAPS to the electrically conductive members; whereby upon activation of the first EAPS by the action of a shaped charge thereon, an electrical signal is generated and transmitted via the first electrical conductors to the one or more detonators to initiate the detonators and thereby detonate the explosive charge to activate the second EAPS to generate therefrom within the field zone an electromagnetic field of sufficient intensity to attenuate penetration of the shaped charge penetrating jet through the dispersal zone.

13. The reactive armor assembly of claim 12 wherein the second EAPS is spaced sufficiently far from the first EAPS that the explosive charge associated with the second

EAPS is detonated by the one or more detonators prior to arrival at the second EAPS of the shaped charge.

14. The reactive armor assembly of claim 12 or claim 13 wherein both the first EAPS and second EAPS comprise respective piezoelectric arrays.

15. The reactive armor assembly of claim 12 or claim 13 wherein at least one of the first EAPS and second EAPS comprises an explosively-pumped flux compression generator, and the assembly further comprises a source of start electrical current operatively connected to the explosively-pumped flux compression generator or generators.

16. The reactive armor assembly of claim 15 wherein the source of start electrical current comprises an electrical power source which is extraneous to the reactive armor assembly and start current electrical leads connect the extraneous power source to the explosively-pumped flux compression generator.

17. The reactive armor assembly of claim 15 wherein the source of start electrical current is a start current piezoelectric crystal array which is electrically connected by start current electrical leads to the explosively-pumped flux compression generator, and is activated by a shaped charge impacting the reactive armor assembly, whereby the reactive armor assembly is independent of any extraneous source of electrical energy.

18. The reactive armor assembly of claim 12 or claim 13 wherein at least one of the first EAPS and second EAPS comprises a piezoelectric array.

19. The reactive armor assembly of claim 12 or claim 13 wherein both the first EAPS and second EAPS comprise respective explosively-pumped flux compression generators.

20. The reactive armor assembly of any one of claims 1 , 2, 11 or 12 in combination with a vehicle having a hull on which the assembly is mounted with its dispersal zone adjacent the hull, and the assembly is independent of any extraneous source of electrical power.

21. The reactive armor assembly of any one of claims 1, 2, 11 or 12 wherein the explosively-activated power source comprises at least one explosively-pumped flux compression generator, and the assembly further comprises at least one start current piezoelectric crystal array electrically connected to the at least one flux compression generator, the piezoelectric array being configured to be activated by the impact of such shaped charge on the assembly to provide a start current to the at least one flux compression generator.