Abstract:
A retention system protects the round stored inside a rotating continuous belt-type magazine, and holds the round securely while allowing it to be readily and easily released prior to firing. The retention system permits all the retaining devices to be easily retracted so that a ramming mechanism of the weapon can push the round into the chamber without interference. The gun tube of the automated weapon houses the round and provides interfaces for all other components to attach. The tube length minimizes the axial movement of the round. The round is held within the tube by a front door assembly and a rear door assembly. The door assembly is made of a crescent-shaped door attached to a pivot shaft, in order to minimize the amount of rotational travel required to open the door for loading or firing the round.

Description:
GOVERNMENTAL INTEREST 
     The invention described herein may be manufactured and used by, or for the Government of the United States for governmental purposes without the payment of any royalties thereon. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates in general to the field of munitions. More specifically, this invention relates to a system and associated method for retaining, securing, and protecting the ammunition within a magazine or within an ammunition feeding mechanism of an automated weapon. 
     BACKGROUND OF THE INVENTION 
     One of the challenges of automating mortar weapons is the design of a system that handles and protects the ammunition. The standard mortar round is typically difficult to restrain securely within a magazine or ammunition feeding mechanism of an automated weapon. The round must be protected from gunfire shock, adverse weather conditions and transportation loads, while remaining ready to be fired without any user handling or intervention. 
     In addition, the mortar round includes delicate features, such as the aluminum fins and propellant charge increments, which must be protected from damage resulting from handling and transportation. To further exacerbate the concerns associated with traditional automated weapons, the ogive geometric shape and design of the mortar round does not provide a useful feature for securing the mortar within the ammunition feeding mechanism. 
     Previous methods of mortar round retention for automatic or semi-automatic weapons included storing the ammunition in a sealed container, clamping the round tightly with a friction hold or by interfacing with the tapered section of the mortar body. Storing the ammunition in a sealed container requires user handling before firing. The use of a retention device against the tapered section of the mortar body is prone to wedging and jamming. Maintaining sufficient friction to retain the round when subjected to transportation and firing loads has proven to be relatively difficult. Furthermore, the force applied to the round decreases over time and with repeated firing loads, with the springs taking a permanent set. 
     While these conventional methods provided a certain level of protection to the ammunition, there still remains a need for a more efficient retention system that secures and protects the ammunition within the feeding mechanism of an automated weapon. 
     SUMMARY OF THE INVENTION 
     The present invention addresses the foregoing concerns and presents a new retention system that protects the round stored inside a rotating continuous belt-type magazine, and that holds the round securely while allowing it to be readily and easily released prior to firing. The retention system permits all the retaining devices to be easily retracted so that a ramming mechanism of the weapon can push the round into the chamber without interference. 
     An ammunition magazine tube of the automated weapon houses the round and provides interfaces for all other components to attach. The tube length restricts the axial movement of the round. 
     The ammunition is held within the tube by a front door assembly and a rear door assembly. Each of these two door assemblies is made of a crescent-shaped door attached to a pivot shaft. The crescent shape permits the door to retain the ammunition during transportation, while minimizing the amount of rotational travel required to open the door for loading or firing the round. 
     The door assembly rotation is guided by two shaft supports for each of the two door assemblies. To open the doors, each door assembly is fitted with a release lever. A front release lever is actuated by the plunger of a firing solenoid and will open both the front and rear doors for firing. A rear release lever is actuated by a loading solenoid, but only opens the rear door, as required, for loading or resupplying ammunition into the magazine. 
     The doors are held in the closed position by torsion springs. The lower door supports provide additional support for the door when they are in the closed position, prevent cantilever type loading on the door shaft, and provide a positive rotational stop for each door. 
     The ammunition is also clamped in place by a formed clamping spring to prevent vibration during transportation. This clamping spring also provides a method of inventory control. When the head of the spring is forced downward by the round, it will fall into the range of a proximity sensor to indicate the presence of ammunition in the cell. The head also interfaces with a cam when the cell is driven to the firing position to further depress the spring, in order to completely release the ammunition prior to firing. 
     A linking collar assembly allows additional cells to be linked together to form a continuous chain. Each cell has four linking collars, two in the front and two in the rear. 
     The present retention system provides positive round retention while remaining readily releasable and protecting the critical areas of the round. The combination of the doors and clamp spring prevents axial movement and vibration of the mortar during transportation and firing loads seen by the system. The present design is not susceptible to jamming from a wedging action because there is no interface with the tapered section of the round. The doors are held closed by the torsion spring and are easily opened by means of solenoids. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in, and constitute part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention. The embodiments illustrated herein are presently preferred, it being understood, however, that the present invention is not limited to the precise arrangements and instrumentalities shown, wherein: 
         FIG. 1  includes  FIGS. 1A, 1B, 1C, and 1D , and represents a schematic view of the operation of an automated weapon that is provided with an ammunition feeding mechanism, according to a preferred embodiment of the present invention; 
         FIG. 2  is an isometric perspective view of the ammunition feeding mechanism shown in  FIG. 1 , such as a rotating, continuous belt-type magazine of the automated weapon, wherein the ammunition feeding mechanism is formed of a plurality of interconnected storage cells, each of which embodies a retention system according to an embodiment of the present invention, and one gun tube clearance cell which ensures that that the gun tube of the automated weapon is clear and unobstructed; 
         FIG. 3  is a partly exploded view of a storage cell that forms part of the ammunition feeding mechanism of  FIG. 2 , illustrating the retention system of the present invention; 
         FIG. 4  is an isometric perspective view of the assembled storage cell of  FIG. 3 , showing a front and rear rotating doors closed; 
         FIG. 5  includes  FIGS. 5A, 5B, 5C, 5D, and 5E , and represents various views of the storage cell of  FIG. 4 ; 
         FIG. 6  is an enlarged, cross-sectional view of the storage cell of  FIG. 5A , taken along line  6 - 6  thereof; 
         FIG. 7  is an isometric perspective view of the storage cell of  FIG. 3 , showing the front and rear rotating doors open; 
         FIG. 8  includes  FIGS. 8A, 8B, 8C, 8D, and 8E , and represents various views of the storage cell of  FIG. 7 ; 
         FIG. 9  is an isometric perspective view of the storage cell of  FIG. 3 , showing the front rotating closed and the rear rotating door open; 
         FIG. 10  includes  FIGS. 10A, 10B, 10C, 10D, and 10E , and represents various views of the storage cell of  FIG. 9 ; 
         FIG. 11  is an isometric perspective view of the storage cell of  FIG. 3 , shown in a loaded state, with both the front and rear rotating doors closed; 
         FIG. 12  includes  FIGS. 12A, 12B, 12C, 12D, and 12E , and represents various views of the storage cell of  FIG. 11 , with  FIG. 12B  being a cross-sectional view of the storage cell of  FIG. 11 , taken along line  12 - 12  thereof; 
         FIG. 13  is an isometric perspective view of the storage cell of  FIG. 4 , further illustrating the retraction of the clamping spring by the cam; 
         FIG. 14  is a front view of the storage cell of  FIG. 13 , illustrating a plunger of a firing solenoid actuator in a retracted position, with the front rotating door closed; 
         FIG. 15  is a front view of the storage cell of  FIG. 14 , illustrating the plunger of the firing solenoid actuator of  FIG. 14  in an extended (or deployed) position, causing the front and rear rotating doors to open; 
         FIG. 16  is an isometric perspective view of the gun tube clearance cell of  FIG. 2 , further illustrating an ultrasonic source in a deactivated state; 
         FIG. 17  is a cross-sectional, side view of the gun tube clearance cell and the ultrasonic source of  FIG. 16 , taken along line  17 - 17  thereof; 
         FIG. 18  is an isometric perspective view of the gun tube clearance cell of  FIGS. 16 and 17 , further illustrating the ultrasonic source in an activated state; 
         FIG. 19  is a cross-sectional, side view of the gun tube clearance cell and the ultrasonic source of  FIG. 18 , taken along line  19 - 19  thereof; and 
         FIG. 20  is a schematic view of the automated weapon of  FIG. 1 , showing the recoiling mass of the automated weapon stowed inside the gun tube clearance cell of  FIGS. 15 through 19 . 
     
    
    
     Similar numerals refer to similar elements in the drawings. It should be understood that the sizes of the different components in the figures are not necessarily in exact proportion or to scale, and are shown for visual clarity and for the purpose of explanation. 
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     With reference to  FIG. 1 , it illustrates an exemplary operation of an automated weapon  5  that is provided with an ammunition feeding mechanism  10 , according to a preferred embodiment of the present invention. In this example, the automated weapon  5  includes a gun tube  30 , and a recoiling mass  20  that translates back and forth within a firing chamber  25 . As used herein, the term “recoiling mass” generally refers to the components of the automated weapon  5  that move in response to the energy of expending an round by the automated weapon  5 . This term may encompass, for example, a breech or a ramming mechanism, recoil cylinders, recoil springs or firing mechanism. 
     While the ammunition feeding mechanism  10  is shown as including four rounds  11 ,  12 ,  13 , and  14 , it should be clear that the ammunition feeding mechanism  10  can be provided with a different number of rounds, wherein each round, i.e.,  11 ,  12 , is respectively stored in a storage cell, i.e.,  105 ,  106  ( FIG. 2 ). 
     As further illustrated in  FIG. 2 , the ammunition feeding mechanism  10 , can be, for example, a rotating, continuous belt-type magazine of the automated weapon  5 . The ammunition feeding mechanism (or magazine)  10  of this particular example, is formed of a plurality of generally similar interconnected storage cells (i.e.,  105 ,  106 ) each of which embodies a retention system  100  according to a preferred embodiment of the present invention. The ammunition feeding mechanism  10  is also comprised of one (or more) gun tube clearance cell  200 , which ensures that the gun tube  30  of the automated weapon  5  is clear and unobstructed. 
     The general operation of the automated weapon  5  will now be described in connection with  FIGS. 1A through 1D .  FIG. 1A  shows the first round  11  being chambered, and the recoiling mass  20  being cocked and latched.  FIG. 1B  shows the recoiling mass  20  unlatched and ramming the first round  11  forward, along the arrow A, causing the first round  11  to be fired through the gun tube  30 . 
       FIG. 1C  shows the first round  11  exiting the gun tube  30 , resulting in a soft recoil effect, wherein the reaction forces ensuing from the firing of the first round  11  cause the recoiling mass  20  to move back, along the arrow B, and to latch.  FIG. 1D  illustrates the recoiling mass  20  latched, with the ammunition feeding mechanism  10  indexed to the next round  12 . While the preferred embodiment is described in terms of a soft recoil effect, it should be amply clear that the present invention is not limited to soft recoil mechanisms, and that an exemplary soft recoil mechanism is presented herein for illustration purpose and does not purport to be the exclusive embodiment covered by the present invention. 
       FIG. 3  is a partly exploded view of the storage cell  105  that forms part of the ammunition feeding mechanism  10  of  FIG. 2 . The storage cell  105  is characterized by the retention system  100  according to a preferred embodiment of the present invention. The storage cell  105  includes a generally cylindrically shaped, hollow canister  300 , and the retention system  100  that is mounted onto the canister  300  for securing and protecting the round, i.e.,  11 , within the ammunition feeding mechanism  10  of the automated weapon  5 , and for further selectively and safely ejecting the round, i.e.,  11 , from its corresponding storage cell, i.e.,  105 . In this embodiment, the canister  300  is open at both its front end  250  and ifs rear end  251 . 
     The retention system  100  is generally formed of a front door assembly  301 , a rear door assembly  303 , a central support collar  379 , and a clamping spring  370 . The front door assembly  301  and the rear door assembly  303  are generally similar in design and function, and thus only the front door assembly  301  will be described in greater detail. 
     Considering now the front door assembly  301 , it generally includes a front door shaft  356 , a front rotating door  380 , a front door release lever  350 , a front door return spring  357 , a first front door shaft support  358 , and a second front door shaft support  308 . 
     The front door shaft  356  is preferably, but not necessarily, a metallic rod whose length is approximately equal to half the length of the canister  300  plus the thickness of the assembled front door linking collars  375 ,  376  and the front rotating door  380 . 
     The front rotating door  380  is made of a crescent-shaped metallic sheet. It is secured to forward end of the front door shaft  356 , so that it selectively opens and closes the front open end  250  of the canister  300 . In this illustration, the front door shaft  356  can be rotated by approximately fifty-five (55) degrees. Concurrently, and as further illustrated in  FIG. 12 , the closed front rotating door  380  provides support to a nose  1205  ( FIG. 12 ) of the round  11 . 
     In addition, as further illustrated in  FIGS. 7 and 8D , the front rotating door  380  includes a circularly shaped inner contour  260  that has a generally similar diameter as that of the front end  250  of the canister  300 . As a result, when the front rotating door  380  is in an open position, the inner chamber  255  of the canister is fully opened and exposed, to allow unhindered expulsion of the round  11 . 
     With reference to  FIGS. 3 and 4 , the front door return spring  357  is firmly secured to the forward end of the front door shaft  356 . The other, or rearward, end of the front door return spring  357  presses against the forward side of the first front door shaft support  358 , in order to keep the front rotating door  380  in a closed position when the storage cell  105  is assembled. The front rotating door  380  includes a lip  382  that engages a lock  387  ( FIG. 3 ), which is mounted on the front end  250  of the canister  300  ( FIG. 4 ). 
     With further reference to  FIGS. 4 and 7 , when the storage cell  105  is assembled, the front door release lever  350  is firmly secured to the rearward end of the front door shaft  356  and rests against the rearward end of the second front door shaft support  308 . As a result of this configuration, when the front door release lever  350  is in a default (i.e., not pressed) state, it rests in an upward position ( FIG. 4 ). However, as illustrated in  FIG. 7 , when it is desired to open the front rotating door  380  and the rear rotating door  385 , the front door release lever  350  is pressed downward to cause the front door shaft  356  to rotate clockwise (as viewed from the front end of the storage cell  105 ). 
     In the embodiment illustrated in  FIGS. 3 and 4 , the first front door shaft support  358  is secured to a collar  358 C, which in turn, is securely mounted on the outer periphery of the collar  300 . Similarly, the second front door shaft support  308  is secured to the central support collar  379 , which in turn, is securely mounted onto the collar  300 . 
     The front door linking collars  375 ,  376  are generally similar in design and construction, and therefore only the collar  375  will be described in more detail. The collar  375  is formed of a cylindrical ring  415  ( FIG. 3 ) having a circular cross-section. The inner diameter of the ring  415  is selected so that the collar  375  can be securely fitted on the front end  250  of the canister  300 . 
     With reference to  FIG. 4 , the collar  375  further includes a shoulder  420  that is provided with two holes  425 ,  430 . The shoulder  420  protrudes outwardly to enable the engagement of the collar  375  to another storage cell on one side, i.e., left side, of the storage cell  105 , in a chain configuration, as shown in  FIG. 2 , by means of two pins  372 ,  373 . Pins  372  and  373  allow for connection to a subsequent magazine cell, while pin  373  also incorporates a roller, which ensures the smooth operation of the magazine  10  as it revolves within its housing. The ring  415  includes an inner, flat shoulder  371  that engages a groove or cutout  391  in cell  300 , thereby axially restraining collar  375  (and similarly collar  376 ). 
     As illustrated in  FIG. 5D , the collar  376  includes a shoulder  435  that is similar in design and function to the shoulder  420 , and that protrudes outwardly to enable the engagement of the collar  376  to another storage cell another side, i.e., right side, of the storage cell  105 , in a chain configuration. 
     Considering now the rear door assembly  303  in connection with  FIGS. 3 and 4 , it is generally similar in design and function to the front door assembly  301 , and includes a rear door shaft  306 , a rear rotating door  385 , a rear door release lever  305 , a rear door return spring  307 , a first rear door shaft support  359 , and a second rear door shaft support  360 . 
       FIG. 3  further illustrates the clamping spring  370  as being formed of a base  390  secured to a preformed spring  392  that is formed of a flat linear arm  377  and a raised head  374 . The base  390  is secured to the bottom of the central support collar  379  by known or available means, such as screws or bolts. 
     In operation, and with further reference to  FIG. 6 , if the storage cell  105  does not contain an round  11 , then the arm  377  of the clamping spring  370  extends generally parallel to the canister  300 , with its head  374  extending through an opening  395  to the inner chamber  255 . The retention system  100  further includes a proximity sensor  600  that is disposed in the vicinity of the clamping spring  370 , and is mounted of the magazine housing so that when the head  374  of the central spring  370  is unbiased by the round  11 , then the head  374  will fall out of the range of the proximity sensor  600 , to indicate that the storage cell  105  does not house the round  11 . 
     If the storage cell  105  contains a round  11 , then, as shown in  FIG. 12 , the head  374  pushes against the round  11  to provide it with lateral support, causing the arm  377  to bend downward away from the canister  300 , and the head  374  to fall into the range of the proximity sensor  600 , to indicate the presence of the round  11 , thus providing an expeditious inventory of the rounds within the ammunition feeding mechanism  10 . 
     As shown in  FIG. 13 , the retention system  100  includes a clamp release cam  1310  that interfaces with a farthermost end  1320  of the head  374 , as the storage cell  105  is advanced to the firing position, in order to depress the clamping spring  370  and to retain it in a depressed state, in order to completely release the round  11 . 
       FIGS. 4 through 15  illustrate various stages of the operation of the storage cell  105 .  FIGS. 4, 5, and 6  represent various views of the storage cell  105  with both the front rotating door  380  and the rear rotating door  385  closed.  FIGS. 7 and 8  represent various views of the storage cell  105  with both the front rotating door  380  and the rear rotating door  385  open. 
     As further illustrated in  FIGS. 13 through 15 , the retention system  100  includes an actuator  1300  that is disposed at a short distance from the front door release lever  350  and the rear door release lever  305 . The actuator  1300  generally includes two solenoids  1400 , each with a plunger  1410  (only one solenoid  1400  and one plunger  1410  are illustrated in  FIGS. 14, 15 ). Both solenoids and plungers are similar in design and function, and therefore only one plunger  1410  will be described herein in more detail. The plunger  1410  is disposed atop the front door release lever  350  and the other plunger (not shown) is disposed atop the rear door release lever  305 . 
     When the plunger  1410  is retracted, as is illustrated in  FIG. 14 , the front door release lever  350  is in an upward position, causing the front rotating door  380  to remain closed. In the illustration shown in  FIG. 15 , the solenoid  1400  is activated so that only the plunger  1410  is extended downward to push down on the front door release lever  350 , causing both the front rotating door  380  and the rear rotating door  385  to be opened. 
     Similarly, when it is desired to open the rear rotating door  385 , as illustrated in  FIGS. 7, 8, 9, and 10 , the solenoid  1400  is activated so that the plunger (not shown) associated with the rear door release lever  305  is extended downward to push down on the rear rotating door  385 . 
     As a result of this design, the firing position is distinct from the loading position. One solenoid plunger  1410  is located above the firing position that is aligned with the front door release lever  350 . The other solenoid plunger (not shown) is located above the rear door release lever  305  in the loading position. The firing solenoid does actuate actuate the rear door release lever  305  and the loading solenoid does not actuate the front door release lever  350 . 
       FIGS. 11 and 12  illustrate various views of the storage cell  105  in a loaded state, with both the front rotating door  380  and the rear rotating door  385  closed, and the front door release lever  350  and the rear door release lever  305  in an upward unbiased position. 
       FIGS. 16 through 19  illustrate various views of the gun tube clearance cell  1600  of  FIG. 2 . While the present exemplary embodiment is described as including a single gun tube clearance cell  1600 , it should be clear that a different number of gun tube clearance cells may be used, without departing from the teaching of the present invention. 
     The gun tube clearance cell  1600  is generally similar in design construction to the storage cell  105 , but is functionally different therefrom. The gun tube clearance cell  1600  is primarily designed to ascertain that the gun tube  30  is clear and unobstructed and to provide a safe transport position for the recoiling system. The gun tube clearance cell  1600  is different than the other storage cells (i.e.,  105 ) because it is not meant to store an round. 
     In a preferred embodiment, the gun tube clearance cell  1600  is open at both ends, so that the recoiling mass  20  of the automated weapon  5  can be stored in the forward position for safety (i.e., not cocked back), as shown in  FIG. 20 . The gun tube clearance cell  1600  includes a generally cylindrically shaped, hollow canister  1605 , an optical (or ultrasonic) release assembly  1610 , an ultrasonic source  1650 , and a chain link assembly  1675 . 
     Considering now the canister  1605 , it is generally similar in design and construction to the canister  300  as described earlier. The chain link assembly  1675  includes two front end linking collars  1677 ,  1679  that are secured to the front end of the canister  1605 , and that are similar in design, construction, and function to the linking collars  375 ,  376 . 
     The chain link assembly  1675  further includes two rear end linking collars  1682 ,  1684  that are secured to the rear end of the canister  1605 , and that are similar in design, construction, and function to the linking collars  377 ,  378 . In this particular embodiment, the gun tube clearance cell  1600  does not include neither a front door nor a rear door, with the understanding that other embodiments of the present invention might selectively include a fixed rear door and/or a rotatable front door that is actuated similarly to the front rotating door  380 , as described earlier. 
     The ultrasonic source  1650  selectively generates and emanates an ultrasonic wave, as it will be explained later, in more detail, in connection with  FIG. 18 . The optical release assembly  1610  is generally formed of a collar  1611  that is mounted on the outer surface of the canister  1605 . A rotatable reflective surface  1612  selectively rotates along an axis that is transverse to the axial direction of the canister  1605 . 
     A lever  1655  is also mounted on the collar  1611 , and is retained by a spring  1656 . The lever  1655  and the rotatable reflective surface  1612  engage each other by means of meshing gears  1657  ( FIGS. 17, 19 ). 
     In operation, when the gun tube clearance cell  1600  is not functional, a spring  1656  retains the lever  1655  in an unbiased position and the rotatable reflective surface  1612  is stowed against the inner surface of the canister  1605  ( FIGS. 16, 17 ). In use, a solenoid that is similar to the solenoid  1400  ( FIGS. 14, 15 ), actuates the lever  1655 , which engages the rotatable reflective surface  1612  and causes it to be lowered from a stowed position ( FIG. 17 ) to an extended position, at for example 45° relative to the longitudinal axis of the canister  1605 . 
     The ultrasonic source  1650  generates an ultrasonic wave  1800  that travels through the opening  1620  in the canister  1605 , to be reflected by the rotatable reflective surface  1612 , parallel to the longitudinal axis of the canister  1605 . The ultrasonic source optical source  1650  further includes a sensor that evaluates the echo of the ultrasonic wave laser beam  1800  that is received back at the sensor. If no echo is received, the gun tube  30  is assumed to be free from obstruction. 
     It is to be understood that the phraseology and terminology used herein with reference to device or element orientation (such as, for example, terms like “front”, “back”, “up”, “down”, “top”, “bottom”, “forward”, “rearward”, and the like) are only used to simplify the description of the present invention, and do not alone indicate or imply that the device or element referred to must have a particular orientation. In addition, terms such as “first”, “second”, and “third” are used herein and in the appended claims for purposes of description and are not intended to indicate or imply relative importance or significance. 
     It is also to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. Other modifications may be made to the present design without departing from the spirit and scope of the invention. The present invention is capable of other embodiments and of being practiced or of being carried out in various ways, such as, for example, in military and commercial applications.