Abstract:
An electronic hand grenade is provided, which includes a body having at least one charge therein. An electronic detonation unit is attached to the body for detonating the at least one charge. A pull pin is removably attached to the electronic detonation unit, for activating the electronic detonation unit upon removal thereof. The electronic detonation unit includes an accelerometer for detecting movement and acceleration of the body, a controller containing an operating program for controlling operation of the electronic detonation unit, a detonator for providing a spark to ignite the at least one charge, and a power source for powering the electronic detonation unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Patent Application No. 61/977,848, filed on Apr. 10, 2014, entitled “Electronically Activated Hand Grenade,” the entire contents of which are incorporated by reference herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention is generally directed to a hand grenade, and, more particularly, to an electronically activated hand grenade. 
         [0003]    Conventional hand grenades  10 , as shown in  FIGS. 1 and 2 , comprise a body  12 , typically fabricated of steel or some other metal, having a main charge  14  and a detonator  16  therein. A chemical delay element or fuse  18  is attached to the detonator  16 . A primer  20  is located adjacent an end of the chemical delay element  18 , opposite from the detonator  16 . A spring loaded handle  22  is pivotably attached to the body  12 , and a pin  26 , engaged with the body  12  and the handle  22 , maintains the handle  22  in a first position ( FIG. 1 ) in which the grenade  10  is deactivated. When the pin  26  is removed, the handle  22  is biased toward a second position ( FIG. 2 ), in which the grenade  10  is activated. However, a user holds the grenade  10  with the handle  22  in the first position until the grenade  10  is thrown. 
         [0004]    In use, a user, e.g., a soldier, pulls the pin  26  out of engagement with the body  12  and the handle  22 , while manually grasping the grenade  10  and maintaining the handle  22  in the first position. Once the handle  22  moves to the second position, e.g., when a user releases the handle  22  while throwing the grenade  10  after removing the pin  26 , a striker  28  underneath the handle  22  rotates and strikes the primer  20 . A flash of heat from the primer  20  ignites the chemical delay element/fuse  18 . The chemical delay element  18  burns down to the detonator  16  within the main charge  14 , creating a chemical spark which set off the main charge  14  within the grenade  10  in a well-known manner. Generally, the chemical delay element  18  should burn down to the detonator  16  and the main charge  14  to set off the grenade  10  in approximately 3 to 5 seconds, giving the user adequate time to throw the grenade  10  a safe distance. 
         [0005]    One disadvantage of such conventional grenades  10  is that the exact delay time that the chemical delay element/fuse  18  provides is not precise, and is sometimes unpredictable. Accordingly, if the grenade  10  does not detonate fast enough, the enemy may have an opportunity to pick up the hand grenade  10  and throw it away or back toward the initial user, leading to injury or death of at least the initial user. Another disadvantage of such conventional hand grenades  10  is that if the hand grenade  10  is inadvertently not thrown far enough, the hand grenade  10 , upon detonation, could potentially injure or kill at least the user who threw the hand grenade  10 . 
         [0006]    Therefore, it would be advantageous to manufacture an improved hand grenade providing a more precise detonation structure and procedure, ensuring that the hand grenade detonates at the proper time, while also preventing detonation of the hand grenade if the hand grenade has not traveled far enough away from the user. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    Briefly stated, one aspect of the present invention is directed to an electronic hand grenade, which includes a body having at least one charge therein. An electronic detonation unit is attached to the body for detonating the at least one charge. A pull pin is removably attached to the electronic detonation unit, for activating the electronic detonation unit upon removal thereof. 
         [0008]    Another aspect of the present invention is directed to a method of detonating an electronic hand grenade including a body having at least one charge therein, an electronic detonation unit attached to the body, including an accelerometer, a controller and a detonator, and a pull pin removably connected to the electronic detonation unit. The method comprises the steps of removing the pull pin to activate the electronic detonation unit, detecting acceleration of the body in at least one of X, Y and Z directions via the accelerometer and determining by the controller whether acceleration has been detected by the accelerometer. 
         [0009]    If acceleration has been detected, the controller determines whether the acceleration corresponds to throwing or rolling. If the detected acceleration corresponds to throwing, the controller determines whether the body has been subjected to an impact. If the body is subjected to an impact, the controller determines whether the body has traveled at least a minimum safe throwing distance. If the body has traveled at least the minimum safe throwing distance, the controller instructs the detonator to detonate the at least one charge and the at least one charge is detonated. If the detected acceleration corresponds to rolling, the controller determines whether the body has traveled at least a minimum safe rolling distance. If the body has traveled the at least minimum safe rolling distance, the controller instructs the detonator to detonate the at least one charge, and the at least one charge is detonated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The following detailed description of a preferred embodiment of the invention will be better understood when read in conjunction with the appended drawings. It should be understood, however, that the disclosure is not limited to the precise arrangements and instrumentalities shown. In the drawings: 
           [0011]      FIG. 1  is a side elevational view of a conventional hand grenade having a chemical delay element in accordance with the prior art; 
           [0012]      FIG. 2  is a cross-sectional elevational view of the conventional hand grenade of  FIG. 1 ; 
           [0013]      FIG. 3  is a cross-sectional elevational view of an electronically controlled hand grenade, according to a preferred embodiment of the invention; 
           [0014]      FIG. 4  is a schematic block diagram of an electronic detonation unit of the hand grenade of  FIG. 3 , which determines detonation of the hand grenade; and 
           [0015]      FIG. 5  is a flow diagram depicting the major operational steps of the electronic detonation unit of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    Certain terminology is used in the following description for convenience only and is not limiting. The words “lower,” “bottom,” “upper” and “top” designate directions in the drawings to which reference is made. The words “inwardly,” “outwardly,” “upwardly” and “downwardly” refer to directions toward and away from, respectively, the geometric center of the hand grenade, and designated parts thereof, in accordance with the present disclosure. Unless specifically set forth herein, the terms “a,” “an” and “the” are not limited to one element, but instead should be read as meaning “at least one.” The terminology includes the words noted above, derivatives thereof and words of similar import. It should also be understood that the terms “about,” “approximately,” “generally,” “substantially” and like terms, used herein when referring to a dimension or characteristic of a component of the invention, indicate that the described dimension/characteristic is not a strict boundary or parameter and does not exclude minor variations therefrom that are functionally similar. At a minimum, such references that include a numerical parameter would include variations that, using mathematical and industrial principles accepted in the art (e.g., rounding, measurement or other systematic errors, manufacturing tolerances, etc.), would not vary the least significant digit. 
         [0017]    Referring to the drawings in detail, wherein like numerals indicate like elements throughout, there is shown in  FIGS. 3-5  a hand grenade, generally designated  100 , having an electronic detonation unit or electronically controlled fuse, according to a preferred embodiment of the present invention. As shown in  FIG. 3 , the hand grenade  100  comprises a body  112 , having a main charge  114 , and a primary charge  118  therein. The body  112  is substantially the same size and shape as the prior art hand grenade  10  and the main charge  114  is substantially the same as the main charge  14  of the prior art hand grenade  10 . An electronic detonation unit  120  is attached to an upper portion of the body  112  and operatively connected to the primary charge  118 , and a pull pin  126  similar to the pin  26  of the prior art hand grenade  10  is operatively connected to the electronic detonation unit  120 . Removal of the pull pin  126  activates the electronic detonation unit  120 , as described further below. 
         [0018]    As shown in  FIG. 4 , the electronic detonation unit  120  includes a logic circuit  128 , e.g., a microcontroller, with memory containing an operating program for the electronic detonation unit  120 , connected with an accelerometer  132 , a detonator  116 , which is operatively connected to the primary charge  118 , and a power source  136  to power the electronic detonation unit  120 , which in the preferred embodiment is a battery. In a preferred embodiment, the battery  136  is a button battery. However, as should be understood by those of ordinary skill in the art, other battery forms or some other power source may alternatively be utilized. As also should be understood by those of ordinary skill in the art, the accelerometer  132  detects movement and acceleration and the detonator  116 , e.g. a spark or bridgewire detonator, provides a spark to ignite the primary charge  118 , which in turn ignites the main charge  114 , in a manner well know by those of ordinary skill in the art. 
         [0019]    When the pin  126  is engaged with the electronic detonation unit  120 , the electronic detonation unit  120  and thus the hand grenade  100  is not activated. When a user pulls the pin  126  out of engagement with the electronic detonation unit  120 , a spring loaded switch  134  is closed, to connect two opposing poles of the electronic detonation unit  120  (poles  2  and  3  in  FIG. 4 ) to thereby apply power from the battery  136  to the accelerometer  132  and the microcontroller  128 , to activate the microcontroller  128  and the accelerometer  132 . When the hand grenade  100  moves, i.e., is thrown or rolled, the accelerometer  132  detects acceleration in the X, Y, and Z directions (as shown in the coordinate system of  FIG. 3 ) and continuously or periodically outputs the detected data X out , Y out , and Z out  to the microcontroller  128  in a manner well known in the art. Alternatively, the acceleration data could be output with a serial, or some other, protocol. If the hand grenade  100  is dropped, and thus freely accelerates under the force of gravity in the Z direction, the accelerometer  132  outputs detected data OGD, identifying such motion. 
         [0020]    The microcontroller  128  calculates the velocity and direction of travel of the thrown or rolled hand grenade  100 , in a manner well understood by those of ordinary skill in the art. The microcontroller  128  also detects time of flight, e.g., via a counter or other such device, in a manner well known by those of ordinary skill in the art. With the calculated velocity, direction and time of flight, the microcontroller  128  continuously or periodically calculates the distance the hand grenade has traveled from the user during flight or rolling movement. When the hand grenade  100  stops, such as for example by hitting the ground, an impulse acceleration is detected. As should be understood by those of ordinary skill in the art, alternative devices for calculating velocity, distance and impact, currently known, or that later become known, may be utilized. 
         [0021]    In operation, as shown in the flow diagram of  FIG. 5 , when the electronic detonation unit  120  is activated, i.e., power applied ( 500 ), the microcontroller  128  first checks to confirm whether the pin  126  is present ( 502 ) in the electronic detonation unit  120 . If the pin  126  is present, an anomaly is detected and the electronic detonation unit  120  is deactivated ( 504 ). No action is taken by the microcontroller  128  if the pin  126  remains in engagement with the electronic detonation unit  120 . Under normal conditions, however, when the pin  126  has been pulled out of engagement with the electronic detonation unit  120 , i.e., the pin  126  is not present, operation of the microcontroller  128  continues ( 506 ) and the microcontroller  128  repeatedly checks whether the data detected by the accelerometer  132  and received by the microcontroller  128  ( 508 ) indicates the presence of acceleration (indicating that the hand grenade  100  has been thrown or rolled). If no acceleration is detected by the accelerometer  132 , the microcontroller  128  makes no further calculations, but merely cycles back through a repetitive feedback loop until acceleration is detected. 
         [0022]    Detected acceleration may be of multiple types. For example, if the hand grenade  100  is thrown in a normal manner, the accelerometer  132  detects a short rapid acceleration, likely in all of the X, Y and Z directions, followed by a period of zero acceleration while the hand grenade  100  is in flight. Impulse acceleration, i.e., impact, is detected once the microcontroller  128  determines an immediate deceleration or complete stop, indicating that the thrown hand grenade  100  has reached its destination. As another example, if the hand grenade  100  is dropped, i.e., free fall, the accelerometer  132  detects acceleration primarily only in the vertical Z direction, followed by an immediate impulse detection, i.e., an immediate stop, indicating that the hand grenade  100  has hit the ground. As yet another example, if the hand grenade  100  is rolled, the accelerometer detects acceleration primarily only in the X and Y directions. 
         [0023]    Thus, once the acceleration data collected by the accelerometer  132  is sent to the microcontroller  128 , the microcontroller  128  determines what type of motion the hand grenade  100  has been subjected to ( 510 ). If the microcontroller  128  determines that the hand grenade  100  has been subjected to free fall, e.g., the hand grenade  100  has been dropped, the detonator  116  is not activated. Rather, the microcontroller  128  cycles back through the repetitive feedback loop until another form of acceleration is detected ( 508 ). Accordingly, if a hand grenade  100  is inadvertently dropped by a user after the pin  126  has been removed, the hand grenade  100  does not detonate and injure or kill the user. Additionally, the user has an opportunity to pick up the hand grenade  100  and either replace the pin  126  or throw/roll the hand grenade  100  as initially intended. 
         [0024]    If the microcontroller  128  determines that the hand grenade  100  has been thrown ( 520 ), the microcontroller  128  also determines when an impact is detected ( 522 ). So long as an impact is not detected, the microcontroller  128  cycles back to assess additional data sent by the accelerometer  132 . Once impact is detected ( 522 ) (indicating the hand grenade  100  has reached its destination), the microcontroller  128  determines, based on calculated velocity and flight time, whether the hand grenade  100  has traveled a minimum safe distance ( 524 ). A minimum safe distance is generally defined by the “wounding radius,” i.e., the distance at which detonation of the hand grenade  100  will not injure the user. For example, when the hand grenade  100  is thrown, a typical minimum threshold value for safe distance may be approximately about 15 meters (49 feet). However, as should be understood by those of ordinary skill in the art, the microcontroller  128  may be programmed with any desired distance, which the manufacturer determines is the safe distance. 
         [0025]    If the microcontroller  128  determines that the hand grenade  100  has traveled a safe distance, the microcontroller  128  instructs the detonator  116  to detonate immediately ( 526 ). The detonator element  116  thus immediately ignites the primary and main charges  118 ,  114 , thereby exploding the hand grenade  100 . Thus, there is no opportunity for the enemy to pick up and throw the hand grenade. Conversely, even if impact is detected, if the microcontroller  128  determines that the hand grenade  100  has not traveled the safe distance, the microcontroller  128  deactivates the hand grenade  100  ( 518 ). Accordingly, the hand grenade  100  does not injure or kill the user who initially threw the hand grenade. Deactivating the hand grenade  100  also ensures that even if the enemy locates and throws the hand grenade  100 , that it will not detonate. 
         [0026]    Alternatively, if the microcontroller  128  determines that the hand grenade  100  has been rolled ( 512 ), e.g., if a soldier rolls the hand grenade  100  into a room, the microcontroller  128  determines whether a safe distance has been traveled ( 514 ). The safe distance when the hand grenade  100  is rolled may or may not be the same safe distance when the hand grenade  100  is thrown. For example, the safe distance when a hand grenade  100  is rolled may be less than the safe distance when the hand grenade  100  is thrown. Once the microcontroller  128  determines that a safe distance for a rolling hand grenade  100  has been traveled, the microcontroller  128  operates in accordance with a programmed instruction ( FIG. 5 , A) ( 516 ). For example, the microcontroller  128  may instruct the detonator  116  to detonate immediately once the hand grenade  100  stops. Alternatively, the microcontroller  128  may instruct the detonator  116  to detonate once the hand grenade  100  is picked up, i.e., acceleration is again detected. Conversely, if the microcontroller  128  determines that the hand grenade  100  has stopped without traveling the minimum safe distance, then the hand grenade  100  is deactivated ( 518 ). Thus, if the hand grenade  100  does not travel a safe distance, it does not detonate, thereby minimizing the chance of injuring or killing the user who initially rolled it. Additionally, even if an enemy rolls or throws the hand grenade  100  back at the initial user, it does not detonate, as it has been deactivated. 
         [0027]    Thus, one advantage of the hand grenade  100  is that the microcontroller  128  is programmed to not detonate, or alternatively to deactivate, if the pin  126  is inadvertently removed, or if under an abnormal circumstance, the microcontroller  128  is activated prior to removal of the pin  126 . If the pin  126  is removed or the hand grenade  100  is dropped accidentally, the microcontroller  128  detects abnormal acceleration, not corresponding to throwing or rolling, and does not activate the hand grenade  100 . Thus, the hand grenade  100  remains safe, allowing the pin  126  to be replaced. 
         [0028]    Another advantage of the hand grenade  100  is that if the hand grenade  100  is thrown short, the microcontroller  128  determines, based on the data received from the accelerometer  132 , that the hand grenade  100  has not traveled a minimum safe distance. The microcontroller  128  is deactivated, and, therefore, does not activate the detonator  116 . Yet another advantage of the hand grenade  100  is that it may be easily used with both the left or right hands. 
         [0029]    As should be understood by those of ordinary skill in the art, the microcontroller  128  may be programmed with additional modes of operation and safety features. The microcontroller  128  may also be wirelessly reprogrammed in the field, using a serial interface, wireless communication, infra-red signal or any other suitable means of communication, as shown in phantom in  FIG. 4 . Further, the hand grenade  100  may be detonated remotely via one or more of such connections. 
         [0030]    Further, the hand grenade  100  may also include a time delay ignition. As shown in  FIG. 4 , the hand grenade  100  may optionally include a spring loaded button  138  operatively connected to the microcontroller  128 , via, for example, connection switch SW 2  (shown in phantom). After removal of the pin  126 , if the button  138  is depressed and held down for a predetermined time, a counter or other indicator within the microcontroller  128  is activated and instructs the detonator  116  to detonate once the counter or other indicator times out. The hand grenade  100  may optionally further include a light  140  ( FIG. 4 ), e.g., an LED light, that flashes once time delay ignition is activated. The light  140  may also flash at an increasing rate up to the time of detonation. 
         [0031]    It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this disclosure is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the disclosure.