Abstract:
A method of providing a defense against a shaped charge uses an outer and an inner armor layer provided with a medial space between these outer and inner armor layers. One or more defensive shaped charges are positioned in the medial space. If the outer armor layer is attacked by ordnance having an offensive shaped charge, one or more of the defensive shaped charges positioned in the medial space is detonated so as to degrade the effectiveness of the offensive shaped charge and prevent penetration of the inner armor layer.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims rights under 35 U.S.C. §119(e) from U.S. Application Ser. No. 60/580,808, filed Jun. 18, 2004 by Paul A. Zank et al. entitled “Active Armor”, the contents of which are incorporated herein by reference. 
         [0002]    This application is a divisional of U.S. Ser. No. 11/156,770, filed Jun. 20, 2005; which is a continuation-in-part of U.S. Ser. No. 10/871,146, filed Jun. 18, 2004; now U.S. Pat. No. 7,104,178; which is a continuation-in-part of U.S. Ser. No. 10/323,383, filed Dec. 18, 2002; now U.S. Pat. No. 6,758,125; which is a continuation-in-part of U.S. serial number PCT/US 2005/020571, filed Jun. 10, 2005, all of which applications are by Paul A. Zank and entitled “Active Armor Including Medial Layer for Producing an Electric or Magnetic Field”, the contents all of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0003]    1. Field of the Invention 
         [0004]    The present invention relates to armaments and more particularly to reactive and active armor. 
         [0005]    2. Brief Description of Prior Developments 
         [0006]    The prior art discloses various arrangements of active and reactive armor in which a medial layer is positioned between an outer and inner armor layer with a medial explosive or nonexplosive layer which disrupts a shaped charge to prevent its penetration of the overall armor system. 
         [0007]    U.S. Pat. No. 4,368,660, for example, discloses an arrangement in which an explosive charge is positioned between two armor layers. On detonation of the explosive, the armor layers are displaced from one another to disrupt the shaped charge jet. 
         [0008]    Systems which disrupt the shaped charge jet may not be entirely suitable for use on relatively lightly armored vehicles since the inner armor layer will have to be substantial enough to protect the occupants of the vehicle from the force generated by the detonation of the explosive layer itself. 
         [0009]    A need, therefore, exists for an active armor system which is suitable for use on a relatively lightly armored vehicle. 
         [0010]    Unarmored military vehicles may also vulnerable to shaped charge weapons. Retrofitting such vehicles with an outer explosive layer to disrupt high the shaped charge jet may not be a satisfactory solution. 
         [0011]    A need, therefore, exists for an active armor system which may be retrofitted on an unarmored vehicle. 
       SUMMARY OF THE INVENTION  
       [0012]    The present invention is an active armor system which includes an outer and an inner armor layer with a medial space between these inner and outer armor layers layer. One or more relatively small shaped charges are positioned on the inner armor layer in the medial space. If the outer armor layer is struck by a projectile having a shaped charge, one or more of the small shaped charges positioned in the medial space near where the projectile has struck the outer armor layer are detonated. The small shaped charges in the medial space are positioned so that when they are detonated, their jets will tend to intersect with or be oppositely directed to the jet from the shaped charge on the projectile. The small shaped charges in the medial space may be detonated by an electrical current produced when a piezoelectric material, an electrostrictive material, or a magnetostrictive material in the outer armor layer is struck by the projectile. Alternatively, the small shaped charges in the medial space may be detonated as a result of being contacted by the jet of the detonated shaped charge on the projectile. The small shaped charges in the medial space may be used in conjunction with the electrical or magnetic fields described in the related applications cited above to disrupt the jet of the shaped charge on the projectile. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0013]    The present invention is further described with reference to the accompanying drawings in which: 
           [0014]      FIG. 1  is a vertical cross sectional view of a preferred embodiment of the active armor system of the present invention; and 
           [0015]      FIG. 2  is a vertical cross sectional view of a preferred embodiment of an alternate preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]    Referring to  FIG. 1 , the active armor system of the present invention is shown generally at numeral  10 . This active armor system  10  includes a front armor layer  11  which would preferably consist of a suitable steel alloy or some other ferromagnetic material. The front armor layer  11  has a front face  12  and a rear face  14 . The conventional shaped charge projectile  15 , against which this system is designed to protect, travels in the direction of the arrow and would ordinarily be expected to impact against the front face  12  of the outer armor layer  11 . Adjacent the front armor layer  11  there is an interior layer  16  which includes a front face and a rear face  20 . This front face would abut the rear face of the front armor layer  11 . The interior layer  16  is comprised of a suitable piezoelectric, electrostrictive, or magnetostrictive material, and specific preferred materials are disclosed in the above cited related applications. For the purpose of this disclosure, it will be understood that the term “projectile” as used herein will encompass any ordnance capable of being armed with a shaped charge which may be a shell, rocket propelled grenade (RPG), missile, air delivered bomb, land or water mine, or improvised explosive device (IED). 
         [0017]    Inwardly adjacent the interior layer  16  there is an electrode  22  which has a front face  24  and a rear face  26 . The front face  24  of electrode  22  would abut the rear face  20  of interior layer  16 . Inwardly adjacent the rear face  26  of electrode  22  there is an interior air space  28 . Alternatively, this air space  28  may be a vacuum space or may be a space filled with a inert gas. On the rear side of the armor system there is a rear armor layer  30  which has a front face  32  and a rear face  34 . Armor layer  11  is electrically connected to solid state power converter  36  by line  38 . Layer  26  is electrically connected to solid state power converter  36  by line  40 . The front face  32  is adjacent air space  38  and the rear face  34  is adjacent a space to be protected  44  as, for example, the interior compartment of a tank or armored personnel carrier. 
         [0018]    There is also a line  46  from power converter  36  to detonator  48  which is connected to shaped charge  50 . Shaped charge  50  is tilted so that when it is detonated it produces an angularly oriented jet  52  which would intersect the jet (not shown) of the projectile  15  when projectile  15  strikes the outer armor layer  11 . There is also a line  54  from power converter  36  to detonator  56  which is connected to shaped charge  58 . Shaped charge  58  is tilted so that when it is detonated it produces an angularly oriented jet  60  which would intersect the jet (not shown) of the projectile  15  when projectile  15  strikes the outer armor layer  11 . It will be seen that the jets  52  and  60  are interlocking so as to protect a relatively large area from projectile  15 . 
         [0019]    In operation, when a shaped charge projectile as, for example, projectile  15  impacts the front face  12  of the front armor layer  11 , the force of that impact is transmitted through the front armor layer  11  to the interior layer  16 . An electrical charge is transmitted to the electrode  22  which produces an electrical field which would tend to disrupt the jet (not shown) of the shaped charge of the projectile  15 . Sufficient electrical current would also be produced to activate detonators  48  and  56  to detonate shaped charges  50  and  58  respectively to produce the interlocking jets  52  and  60  which would also disrupt the jet (not shown) from the projectile  15 . It will be understood that the interlocking jets  52  and  60  may be used alone to disrupt the jet (not shown) from the projectile  15  in a system in which an electrical field in medial space  28  is not produced. 
         [0020]    Referring to  FIG. 2 , another embodiment of the active armor system of the present invention is shown generally at numeral  110 . This active armor system  110  includes a front armor layer  111  which would preferably consist of a suitable steel alloy or some other ferromagnetic material. The front armor layer  111  has a front face  112  and a rear face  114 . The conventional shaped charge projectile  115 , against which this system is designed to protect, travels in the direction of the arrow and would ordinarily be expected to impact against the front face  112  of the outer armor layer  111 . Adjacent the front armor layer  111  there is an interior layer  116  which includes a front face and a rear face  120 . This front face would abut the rear face of the front armor layer  111 . The interior layer  116  is comprised of a suitable piezoelectric, electrostrictive, or magnetostrictive material, and specific preferred materials are disclosed in the above cited related U.S. application Ser. No. 10/871,146. For example, if a magnetostrictive material is selected, it would preferably be Terfernol which has a formula of Tb.sub0.27 Dy.sub0.73 Fe.sub2. Alternatively the magnetstrictive material may be a Terfernol-D alloy (“Doped” Terfernol) which has a formula of Tb.sub0.27.Dy.sub0 73 Fe.sub1.95 and which has an additive which is a Group III or Group IV element such as Si or Al. Other magnetostrictive materials which may be suitable include TbFe 2  and SmFe 2 . 
         [0021]    If a piezoelectric material is used, preferred piezoelectric ceramics would be barium titanate, lead zirconate titanate (PZT) and quartz. Other suitable piezoelectric ceramics may be strontium titanate, potassium tantalite niobate, potassium tantalite, lithium niobate, and barium sodium niobate. If an electrostrictive ceramic material is used, preferred materials would be lead magnesium niobate and lead titanate. 
         [0022]    Inwardly adjacent the interior layer  116  there is an electrode  122  which has a front face  124  and a rear face  126 . The front face  124  of electrode  122  would abut the rear face  120  of interior layer  116 . Inwardly adjacent the rear face  126  of electrode  122  there is an interior air space  128 . Alternatively, this air space  128  may be a vacuum space or may be a space filled with a inert gas. On the rear side of the armor system there is a rear armor layer  130  which has a front face  132  and a rear face  134 . Armor layer  111  is electrically connected to solid state power converter  136  by line  138 . Layer  126  is electrically connected to solid state power converter  136  by line  140 . The front face  132  is adjacent air space  138  and the rear face  134  is adjacent a space to be protected  144  as, for example, the interior compartment of a tank or armored personnel carrier. 
         [0023]    There is also a line  146  from power converter  136  to detonator  148  which is connected to shaped charge  150 . Shaped charge  150  is tilted so that when it is detonated it produces an angularly oriented jet  152  which would intersect the jet (not shown) of the projectile  115  when projectile  115  strikes the outer armor layer  111 . There is also a line  154  from power converter  136  to detonator  156  which is connected to shaped charge  158 . Shaped charge  158  is tilted so that when it is detonated it produces an angularly oriented jet  160  which would intersect the jet (not shown) of the projectile  115  when projectile  115  strikes the outer armor layer  111 . It will be seen that the jets  152  and  160  are interlocking so as to protect a relatively large area from projectile  115 . 
         [0024]    In operation, when a shaped charge projectile as, for example, projectile  115  impacts the front face  112  of the front armor layer  111 , the force of that impact is transmitted through the front armor layer  111  to the interior layer  116 . An electrical charge is transmitted to the electrode  122  which produces an electrical field which would tend to disrupt the jet (not shown) of the shaped charge of the projectile  115 . Sufficient electrical current would also be produced to activate detonators  148  and  156  to detonate shaped charges  150  and  158  respectively to produce the interlocking jets  152  and  160  which would also disrupt the jet (not shown) from the projectile  115 . It will be understood that the interlocking jets  152  and  160  may be used alone to disrupt the jet (not shown) from the projectile  115  in a system in which an electrical field in medal space  128  is not produced. There are also a plurality of additional shaped charges such as shaped charges  162 ,  164 ,  166 ,  168  and  170  mounted on inner armor layer  130  and perpendicularly oriented with respect to the medial space. In this embodiment shaped charges  162 ,  164 ,  166 ,  168 , and  170  would not be detonated electrically, but instead could be detonated by the jet (not shown) of the projectile  115  in the event they would be contacted by that jet. If detonated, the jets from shaped charges  162 ,  164 ,  166 ,  168 , and  170  would be in an opposite direction to the jet (not shown) of the projectile  115 . For example, jet  172  would be produced in the event shaped charge  162  would be contacted by the jet (not shown) of the projectile  115 . It will be understood that the shaped charges  162 ,  164 ,  166 ,  168 , and  170  could be used in conjunction with shaped charges  150  and  158  so that if the jet (not shown) of the projectile was not sufficiently disrupted by interlocking jets  152  and  160 , it would be further disrupted by jet  172 . A system having such a dual layer of defensive jets might also be able to defeat a projectile having two successively detonated shaped charges. 
         [0025]    It will be understood that in the foregoing described embodiment shown in  FIG. 2  that it would be possible in various situations to delete the shaped charges  158  and  160  which are detonated by the electrically activated detonators  148  and  150  and substitute suitable shaped charges which would be detonated by the gas jet in an attacking projectile. In such an embodiment the interior layer  116  of a suitable piezoelectric, electrostrictive, magnetostrictive material and related circuitry between that material and the detonators could also, of course, be deleted. 
         [0026]    It will be appreciated that an active armor system has been described which is adapted for use on a lightly armored vehicle or retrofitted onto an unarmored vehicle since the amount of explosive used in a relatively small number of shaped charges which might be detonated by a projectile attacking the vehicle would be relatively small as compared with a relatively large explosive layer used in prior art reactive armor systems. Furthermore, in the active armor system of this invention any detonation of the shaped charges incorporated into the armor system would be directed away from the occupants of the vehicle. 
         [0027]    While the present invention has been described in connection with the preferred embodiments of the various figures, it is to be understood that other similar embodiments may be used or modifications and additions may be made to the described embodiments for performing the same function of the present invention without deviating therefrom. Therefore, the present invention should not be limited to any single embodiment, but rather construed in breadth and scope in accordance with the recitation of the appended claims.