Patent Publication Number: US-9897405-B2

Title: Mini-gun with access door

Description:
RELATED APPLICATION AND PRIORITY CLAIM 
     This application is a continuation of and claims the priority of U.S. patent application Ser. No. 14/893,162, entitled “Mini-Gun with Improved Access Door,” which is incorporated herein by reference. This application claims priority to, and incorporates by reference the following: Patent Cooperation Treaty (PCT) patent application serial number PCT/US14/40767, filed Jun. 3, 2014, which claims priority to U.S. provisional patent application No. 61/830,547, filed Jun. 3, 2013, entitled “Mini-Gun with Improved Access Door” which is incorporated herein by reference. 
    
    
     BACKGROUND 
     This invention relates generally to Gatling-type miniguns. More specifically, it relates to an improved access door assembly for the delinking feeder of a Gatling-type minigun. 
     Gatling-type miniguns have been known for many years. The Gatling-type minigun is a multi-barreled machine gun with a high rate of fire (2,000 to 6,000 rounds per minute). It features Gatling-style rotating barrels with an external power source, such as an electric motor. One previous example of such a gun is described in U.S. Pat. No. 7,971,515 B2, entitled “Access Door for Feeder and Delinker of a Gatling Gun,” which is incorporated herein by this reference. Long existing motivations in the design of Gatling-type miniguns have been to minimize jams, extend the operational life and improve ease of use of such guns. 
     Gatling-type miniguns include a delinking feeder assembly, which is an ammunition feed device that receives an ammunition belt of linked cartridges, sequentially separates or “delinks” the cartridges from the ammunition belt, and feeds the cartridges to the minigun for firing. An access door assembly is mounted on the delinking feeder assembly for providing access to the interior of the delinking feeder. It is a principal object of the present invention to provide an improved access door assembly for a delinking feeder of such a minigun. 
     Additional objects and advantages of the invention will be set forth in the description that follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations pointed out in the appended claims. 
     SUMMARY 
     To achieve the foregoing objects, and in accordance with the purposes of the invention as embodied and broadly described in this document, there is provided a delinking feeder for receiving a belt of linked cartridges, separating the cartridges from the belt, and feeding the separated cartridges to a minigun for firing. The delinking feeder includes a housing and an access door mounted to the housing and movable between a closed position and an open position. The access door includes an enclosed recess for receiving a tongue having a first contact surface for contacting and securing a linked cartridge positioned in the delinking feeder when the access door is in the open position. The tongue includes a second contact surface for guiding a cartridge positioned in the delinking feeder when the access door is in the closed position. When the access door is in the closed position, the tongue is in a retracted position and the tongue second contact surface can guide a cartridge positioned in the delinking feeder. The enclosed recess is covered so that when the access door is in the closed position and the tongue is in the retracted position, the tongue does not protrude through the access door. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings and appendices, which are incorporated in and constitute a part of the specification, illustrate the presently preferred embodiments of the invention and, together with the general description given above and the detailed description of the preferred methods and embodiments given below, serve to explain the principles of the invention. 
         FIG. 1A  is a top perspective view showing a side of an embodiment of an electrically-powered minigun that includes one embodiment of an improved feeder door assembly according to the present invention. 
         FIG. 1B  is a top perspective view showing the other side of the minigun of  FIG. 1A . 
         FIG. 2  is a perspective view showing an ammunition belt of the prior art. 
         FIG. 3  is a perspective view showing the interior of a prior art delinking feeder. 
         FIG. 4  is a top perspective view of the delinking feeder of the minigun of  FIGS. 1A and 1B , showing one embodiment of a feeder door assembly according to the present invention with the access door in a fully open position. 
         FIG. 5  is a top perspective view of the delinking feeder of  FIG. 4 , showing the improved feeder assembly with the access door in a closed position. 
         FIG. 6  is an exploded view of one embodiment of an improved feeder door assembly according to the present invention. 
         FIG. 7  is a top perspective view of the access door of the feeder door assembly of  FIG. 6 . 
         FIG. 8  is a bottom perspective view of the access door of  FIG. 7 , showing the door recess. 
         FIG. 9  is a side view of the feeder door tongue of the feeder door assembly of  FIG. 6 . 
         FIG. 10  is a top perspective view of the feeder door tongue of  FIG. 9 . 
         FIG. 11  is a top plan view of the feeder door tongue of  FIG. 9 . 
         FIG. 12  is a perspective cross-sectional view of a portion of the feeder door assembly of  FIG. 6 , showing the tongue and the torsion spring under tension with the access door closed. 
         FIG. 13  is a bottom perspective view of the feeder door assembly of  FIG. 6  with the access door closed, showing the tongue disposed in the access door recess. 
         FIG. 14  is a side elevation view of the feeder door assembly of  FIG. 6  with the access door closed. 
         FIG. 15  is a cutaway perspective view of the feeder door assembly of  FIG. 6 , showing the access door mounted to the feeder housing and in the closed position. 
         FIG. 16  is a perspective view of a portion of the interior the feeder housing, showing the housing latch aperture for receiving the latch pin of the feeder door assembly of  FIG. 6 . 
         FIG. 17  is a perspective view of a portion of the interior of the feeder housing, showing a housing hinge aperture for receiving the hinge pin of the feeder door assembly. 
         FIG. 18  is perspective view of another embodiment of an improved feeder door assembly according to the present invention. 
         FIG. 19  is an exploded view of the feeder door assembly of  FIG. 18 . 
         FIG. 20  is an enlarged perspective view of the feeder housing with door assembly closed, illustrating how the housing and assembly provide an enclosed environment for operation of the delinking feeder. 
         FIG. 21  is a side view of an alternative embodiment of the feeder door tongue of an improved feeder door according to the present invention. 
     
    
    
     DESCRIPTION 
     A preferred embodiment of a feeder door assembly according to the present invention is shown and generally designated by the reference numeral  30 . 
       FIGS. 1A and 1B  illustrate a 7.62×51 mm minigun  10  suitable for use with the present invention. The minigun  110  includes a barrel assembly  12 , an electric drive motor  14  to rotate the barrel assembly  12 , a delinking feeder  16 , a clutch assembly  18 , a gun housing assembly  20 , a gun control unit  22 , and a spade grip  23 . The barrel assembly  12  includes a barrel clamp assembly  25 , a plurality of barrels  24  circumferentially mounted to the barrel clamp assembly  25 , and a flash suppressor  26 . Ammunition is fired sequentially through the barrels  24  in a known fashion, i.e., first one barrel is used, then the next, then the next, etc. An electric cable  28  supplies power from the gun control unit  22  to the drive motor  14 . The delinking feeder  16 , which is an ammunition feed device, is engaged and disengaged via the electric cable  28 . To provide access to the interior of the delinking feeder  16 , a feeder door assembly  30  is mounted on the delinking feeder  16 . The feeder door assembly  30  includes an access door  32  that is movable between a first closed operative position and a second open position to facilitate the loading of an ammunition belt  101  of linked cartridges  80 . A portion of such an ammunition belt is depicted in  FIG. 2 . 
     As is well known to those of skill in the art, in the operation of the minigun  10 , the drive motor  14  causes the barrel assembly  12  to rotate, and each barrel  24  fires sequentially in rapid succession. During such operation, the delinking feeder  16  receives the ammunition belt  101  of linked cartridges  80  (see  FIG. 2 ), sequentially separates or “delinks” the cartridges  80  from the ammunition belt  101  and feeds the cartridges  80  to the minigun firing mechanism (not shown). 
     Still referring to  FIGS. 1A and 1B , when an arming switch on the gun control unit  22  is activated, and one or both firing buttons are then depressed, the gun will fire. When the firing buttons are released, the delinking feeder  16  is disengaged so the ammunition supply is discontinued. The electric drive motor  14  continues to rotate for about 200 to 400 milliseconds so that the weapon is cleared of remaining ammunition before stopping. A booster motor override control button on the gun control unit  22 , when depressed, activates an ammunition booster motor on the ammunition magazine (not shown) to facilitate the loading of the weapon. The booster motor pushes the ammunition belt  101  from the ammunition magazine, through the feed chute, and to the weapon where it is inserted in the delinking feeder  16 , readying the weapon for firing. 
     Referring to  FIG. 2 , each of the cartridges  80  in the ammunition belt  101  includes a cylindrical hollow casing  84  comprising the rear portion of cartridge  80 . A primary conical tapered shoulder  81  extends from casing  84  to a conical tapered neck  82 . Neck  82  extends from the shoulder  81  to a projectile or bullet  83 . 
       FIG. 3  illustrates internal components of a prior art delinking feeder  16 . As shown in  FIG. 3 , a guide assembly  53  includes feeder shaft  90  that rotates (in a direction indicated by arrows R) on an axis that is parallel to the axis about which the barrel assembly  12  rotates. During operation, the guide assembly  53  continuously rotates to receive the ammunition belt  101 , to remove cartridges  80  from the belt, and to feed the cartridges  80  for firing. Securely mounted to the feeder shaft  90  is a series of components, including a push rod guide  49 , a toothed drive gear  51 , sprockets  55 ,  56 , a stripper sleeve  52  (including sprockets  54 ,  57  and  58 ), and a feeder sprocket  59 . The drive motor  14  is rotationally coupled, via the drive gear  51 , to the feeder shaft  90  and the push rod guide  49 , sprockets  55 ,  56 , stripper sleeve  52 , and feeder sprocket  59 . Each of the sprockets  54 - 58  has seven equally spaced grooves, with each groove having a generally semi-cylindrical shape for receiving a cartridge  80 . Sprockets  55  and  56  comprise a cartridge holding construct for holding cartridges  80  that are linked to an ammunition belt  101  that has been inserted into the delinking feeder  16 . 
     Still referring to  FIG. 3 , the guide assembly  53  includes a plurality of push rods  85 , with one push rod  85  corresponding to each barrel  24  of the minigun  10 . For example, in a minigun with a barrel assembly having six barrels  24 , the guide assembly  53  has six push rods  85 . The push rod guide  49  has a generally cylindrical body with longitudinal slots  50 A uniformly distributed about its surface. Each of the push rods  85  can move longitudinally inside its associated longitudinal slot  50 A. An arcuate outer surface  50 B extends between each adjacent pair of slots  50 A. Each groove in a sprocket  54  to  59  is aligned with one of the slots  50 A. Each slot  50 A slidably receives a push rod  85 . Each push rod  85  has a wheel  86  rotatably secured to its rearward end by an axle  87  that extends outwardly from the outer face of the push rod  85 . Each wheel  86  is confined within a spiral grooved channel, represented in  FIG. 3  by the broken lines  88 , which is incorporated into a feeder cam housing  36 , as shown in  FIG. 1B . As the push rod guide  49  is rotated about its axis by means of the drive motor  14 , each of the push rods  85  is constrained by its respective drive wheel  86  to follow the path of the spiral channel  88 , thereby slidably moving forward and backward in its associated longitudinal slot  50 A with each rotation of the push rod guide  49 . As a push rod  85  moves forward toward the drive gear  51 , the push rod distal end  91  engages the rear of a cartridge  80  and pushes the cartridge  80  forward. As the cartridge  80  is driven forward, it is freed, or delinked, from the link  100  holding it (see  FIG. 2 ) and is pushed toward and into the feeder sprocket  59  to be handed off to the minigun firing mechanism (not shown). 
     Still referring to  FIG. 3 , the stripper sleeve  52  (which includes sprockets  54 ,  57  and  58 ) is designed to receive and prevent longitudinal movement of a cartridge link  100  in the ammunition belt  101  so that a cartridge  80  can be pushed free of its associated link  100  by one of the push rods  85 , i.e., the stripper sleeve  52  “holds” the cartridge link  100  while the cartridge  80  is pushed free by one of the push rods  85 . The feeder sprocket  59  receives each cartridge  80  that is separated from the ammunition belt  101 , and then hands off the cartridge  80  for firing. 
     As previously mentioned, the feeder door assembly  30  facilitates the loading of the ammunition belt  101 . Referring now to  FIGS. 4-15 , one embodiment of the improved feeder door assembly  30  includes a single access door  32  having an enclosure  126  defining a recess  124  in an inner surface  122  of the access door  32 . The access door  32  includes mounting sleeve portions  138 ,  140  for pivotally mounting the door  32  on a door hinge pin  240 , which in turn is mounted to the feeder housing assembly (see  FIG. 15 ). The access door  32  is movable between a closed position, as shown in  FIG. 5 , and an open position, as shown in  FIG. 4 . The access door  32  includes a tongue  110  that also is pivotally mounted to the door hinge pin  240  and is configured for contacting and securing a linked cartridge  80  in the delinking feeder sprockets  55 ,  56  and stripper sleeve  52  when the access door  32  is in the open position (or in a partially open position). The tongue  110  is movable between a retracted position, wherein a portion of the tongue  110  is stored in the recess  124  (see  FIGS. 12-14 ) and a deployed position, wherein a portion of the tongue  110  is deployed from the access door  32  (see  FIG. 4 ). The tongue  110  includes a spring recess  114  for holding a torsion spring  112 . The torsion spring  112  is under tension and causes the tongue  110  to pivot about the pin  240  to the deployed position when the door  32  is in the completely opened or partially opened position, as can be seen in  FIG. 4 . When the access door  32  is in the closed position, as can be seen in  FIG. 12 , a portion of the tongue  110  is disposed in the door recess  124 . 
     As can be seen in  FIGS. 6 and 9-15 , the tongue  110  has a bottom surface including a first contact surface  200  and a second contact surface  202 . The first contact surface  200  is provided for bearing against a cartridge  80  when the door  32  is in a partially open position. The second contact surface  202  is configured to have a profile that matches the profile of the access door inner surface  122  (see  FIGS. 13-14 ) so that, when the access door  32  is closed, the inner door surface  122  and the second contact surface  202  form a substantially continuous sliding surface for helping to control the cartridge  80  as it is fed into the feeder sprocket  59 . 
     The tongue  110  includes a stop tab  220  at one end and a hinge pin opening  250  at the other end. As shown in  FIG. 15 , a door hinge pin  240  extends through the opening  250  to pivotally mount the tongue  110  to the base  120 . The door hinge pin  240  extends into hinge apertures  132  in the feeder housing  34  (see  FIG. 17 ) on either side of the feeder door assembly  30 . The torsion spring  112  is also mounted to the door hinge pin  240  with its legs extending into the spring recess  121  extending along a length of the tongue  110  (see  FIGS. 10-12 and 15 ). The torsion spring  112  generates a force that causes the tongue  110  to pivot about the hinge pin  240  and that displaces the tongue  110  to a deployed position when the door  32  is in the completely opened position illustrated in  FIG. 4  (or when the door  32  is in a partially opened position). When the access door  32  is in a partially opened position, the first contacting portion  200  of tongue  110  contacts the casing  84  of a cartridge  80  positioned in the delinking feeder  16 . As a user moves the door  32  in the direction of arrow A from the opened position of  FIG. 4  toward the closed position of  FIG. 5 , the force generated by the torsion spring  112  is overcome as the spring  112  is compressed, and the door recess enclosure  126  is moved downwardly over the tongue  110  to the position illustrated in  FIGS. 12-15 . 
     The access door  32  can be opened in the direction of arrow B to a completely opened position, as shown in  FIG. 4 , to allow greater access to the interior of the delinking feeder  16  so that a user can position a cartridge  80  in the interior of the delinking feeder  16 . Referring to the embodiment of the tongue  110  in  FIG. 21 , the degree to which the torsion spring  112  can displace the tongue  110  outwardly from door recess  124  is controlled by a rotational stop tab  222  disposed near the tongue opening  250 . The rotational stop tab  222  has two opposing surfaces  224 ,  226  that limit the range of rotational travel of the tongue  110  and the access door  32 . One surface  224  limits the rotation of the tongue  110  with respect to the access door when it contacts the recess enclosure  126  and thereby limits the degree to which the torsion spring  112  can displace the tongue  110  outwardly from door recess  124 . For example,  FIG. 4  illustrates the door  32  in an open position in which the tongue  110  is outwardly displaced by the torsion spring  112  from the door recess  124  to the greatest extent possible. The other surface  226  limits the range of rotational travel of the door  32  with respect to the feeder housing  34  to prevent the door  32  from opening too far when it is in the fully open position. 
     With the tongue embodiment of  FIG. 21 , when the door  32  is in the completely open position (see  FIG. 4 ), the tongue first contact surface  200  is spaced apart from, above, and not contacting a cartridge  80  in the delinking feeder. When the door  32  is moved from the completely open position in the direction of arrow A in  FIG. 4 , the tongue  110  moves simultaneously with the door  32  in the same direction of travel as the door  32  until the tongue first contact surface  200  contacts and bears against a cartridge  80  positioned in the delinking feeder  16 . Continuing to close the door  32  in the direction of arrow A compresses the torsion spring  112  and forces the recess enclosure  126  downwardly over the tongue  110  so that the tongue  110  is in a retracted position with a portion of the tongue  110  disposed within the door recess  124  (see  FIGS. 12-15 ). 
     Referring again to  FIGS. 4-5 and 20 , a shelf  42  is formed in the delinking feeder housing. With the door  32  in the open position of  FIG. 4 , the deployed tongue  110  is displaced outwardly to the fullest extent possible. As the door  32  is moved downward in the direction of arrow A from the open position of  FIG. 4  to the closed position of  FIG. 5 , the contact surface  200  of the tongue  110  bears against a cartridge  80 , which prevents downward movement of tongue  110 . As the door  32  is moved to the fully closed position, as shown in  FIG. 14 , the stop tab  220  comes to rest on the shelf  42  and the tongue retracts into the door recess  124 . When the door  32  is subsequently opened, the stop tab  220  is lifted off the shelf  42 . 
     As can be seen in  FIG. 14 , when the door  32  is closed, the second contact surface  202  of the bottom of tongue  110  is positioned over the cartridges  80  in the delinking feeder. As previously explained, the second contact surface  202  is configured to have a profile that matches the profile of the access door inner surface  122  (see  FIGS. 13-14 ). In this configuration, when the access door  32  is closed, the inner door surface  122  and the second contact surface  202  form a substantially continuous sliding surface for helping to guide the cartridge  80  as it is feed into the feeder sprocket  59  of the delinking feeder  16 . 
     Referring again to  FIGS. 6 and 18-19 , the feeder door assembly  30  also includes a spring-loaded latch  150  for locking the access door  32  when it is in the closed position. In the embodiment of  FIG. 6 , the latch  150  includes a housing  152  that is integrally formed with the access door  32 , a latch pin  154  for engaging an aperture  160  in the housing  34  (see  FIG. 16 ), a latch compression spring  156  for urging the latch pin  154  into the housing latch aperture  160  when the door  32  is in the closed position, and a latch release lever  158  for disengaging the latch pin  154  from the housing latch aperture  160  to allow the access door  32  to be opened. In the embodiment of  FIGS. 18-19 , a separate latch cover  151  is mounted to the latch housing  152  using screws  153  and threaded inserts  155 . As shown in  FIG. 19 , with this embodiment, the latch pin  154  and release lever  158  can be integrated into a single unit, 
     A user operates the feeder door assembly  30  as follows. To open the closed access door  32  and access the interior of the delinking feeder  16 , a user manually displaces the latch lever  158  inwardly in the direction of arrow C (see  FIG. 18 ) to disengage the latch pin  154  from the housing latch aperture  160 . The user then can open the access door  32  in the direction of arrow B (see  FIG. 4 ) from the closed position of  FIG. 5  to the completely open position of  FIG. 4 . With an ammunition belt  101  and associated cartridges  80  inserted into the delinking feeder  16  in the manner known in the art, the user can place one or more fingers of one hand on a cartridge  80  to hold the cartridge in place, and with the other hand, can move the door  32  from the completely open position to a partially open position with the first contact surface  200  of the bottom surface of tongue  110  resting on and holding the cartridge  80  in place. The user then can remove his finger(s) from the cartridge  80  and move the door  32  from the partially opened position to the closed position of  FIG. 5  such that latch pin  154  snaps into the housing latch aperture  160  and holds door  32  in the closed position. 
     The improved feeder door assembly of the present invention provides a number of advantages over prior art feeder door assemblies. Because it utilizes a single door, it reduces loading time in comparison to prior art door systems that utilize a pair of side-by-side access doors. In addition, the improved feeder door assembly eliminates jams that are prevalent with prior art door systems that utilize a single door. Moreover, because the improved feeder door assembly provides an enclosed environment for the delinking feeder, it provides better protection from dust and debris than prior art door systems. 
     Upon reading this disclosure, those skilled in the art will appreciate that various changes and modifications may be made to the preferred embodiments of the invention and that such changes and modifications may be made without departing from the spirit of the invention. Therefore, the invention in its broader aspects is not limited to the specific details, representative devices, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the general inventive concept.