Patent Publication Number: US-9903679-B1

Title: Minigun with improved barrel clamp

Description:
RELATED APPLICATION AND PRIORITY CLAIM 
     This application is a continuation of and claims the priority of U.S. patent application Ser. No. 14/893,158, entitled “ Minigun with Improved Barrel Clamp,” 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/US14/40626, filed Jun. 3, 2014, which claims priority to U.S. provisional patent application No. 61830553, filed Jun. 3, 2013, entitled: Minigun with Improved Barrel Clamp, which is incorporated herein by reference. 
    
    
     BACKGROUND 
     This invention relates generally to Gatling-type miniguns. More specifically, it relates to an improved barrel clamp assembly for an electrically powered 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 barrel assembly for holding and rotating barrels. It is a principal object of the present invention to provide an improved barrel clamp assembly for a barrel assembly 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 an improved barrel clamp assembly for a multi-barreled minigun. In some embodiments, the barrel clamp assembly includes a barrel clamp tube having a front end, a rear end, and a plurality of longitudinal openings extending along a portion the length of the tube between the front end and the rear end. An impeller is mounted in the barrel clamp tube between the tube front end and the tube rear end. In one advantageous embodiment, the impeller includes a plurality of impeller blades that are spaced around a periphery of the impeller, that project forward from a rear flange portion of the impeller and that define a plurality of air channels. 
     In some embodiments of a barrel assembly that utilize a barrel clamp tube according to the present invention, the barrel assembly includes a barrel clamp tube having plurality of longitudinal openings, a flash suppressor mounted to the front end of the barrel clamp tube, and a barrel clamp collar mounted to the rear end of the barrel clamp tube. An impeller is mounted to the barrel clamp tube between the flash suppressor and the barrel clamp collar. 
     In this configuration, the improved barrel clamp assembly provides a lightweight barrel clamp with improved performance and cooling characteristics. 
    
    
     
       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 one side of an electrically-powered minigun that includes one embodiment of an improved barrel clamp 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 rear perspective view of the improved barrel clamp assembly of the minigun of  FIGS. 1A and 1B . 
         FIG. 5  is a side elevation view of the barrel clamp assembly of  FIG. 4 . 
         FIG. 6  is a cross-sectional side elevation view of the barrel clamp assembly of  FIG. 4 , illustrating the barrel clamp collar, impeller and flash suppressor mounted to the barrel clamp tube. 
         FIG. 7  is a rear end elevation view of the barrel clamp assembly of  FIG. 4 . 
         FIG. 8  is a front perspective view of the impeller of the barrel clamp assembly of  FIG. 4 , which is one embodiment of an impeller according to the present invention. 
         FIG. 9  is a front elevation view of the impeller of  FIG. 8 . 
         FIG. 10  is front perspective view of another embodiment of an improved barrel clamp assembly according to the present invention. 
     
    
    
     DESCRIPTION 
     A preferred embodiment of a barrel clamp assembly according to the present invention is shown and generally designated by the reference numeral  25 . In the context of the specification, the terms “rear” or “rearward” mean in the direction towards the chamber end of the barrels  24 , while the terms “front” or “forward” mean in the direction towards the muzzle end of the barrels  24 . 
       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 , an access door assembly  30  is mounted on the delinking feeder  16 . The access 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. 
     Referring now to  FIGS. 4-10 , a preferred embodiment of the barrel clamp assembly  25  includes a barrel clamp tube  502  for holding the barrels  24  in a circumferential, spaced relationship. The barrel clamp tube  502  has a plurality of longitudinal openings  503 , each of which extends along a substantial portion of the length of the barrel tube clamp  502 . A flash suppressor  26  is mounted to the front end  520  of the barrel clamp tube  502  and a barrel clamp collar  505  is attached to the rear end  522  the barrel clamp tube  502 . According to one novel aspect of the barrel clamp assembly  25 , an impeller  504  is mounted in the barrel clamp tube  502  between the barrel clamp collar  505  and the flash suppressor  26  for providing improved cooling of the barrels  24 . 
     As can be seen in  FIGS. 4-7 , the barrel clamp collar  505  is a ring-like body of one-piece construction that includes an attachment portion  524  that is adapted for attaching to the tube rear end  522 , such as by rivets or other suitable attachment means. An inwardly projecting flange portion  526  has six barrel cutouts  506  for receiving the barrels  24  and holding them parallel to the longitudinal main axis D of the barrel clamp assembly  25  and the barrel clamp tube  502 . 
     The flash suppressor  26  has a can-like body of one-piece construction with an open forward portion  512  and a rear panel  513  that has six barrel apertures  516  for receiving the barrels  24  and holding them parallel to the longitudinal main axis D. The flash suppressor barrel apertures  516  are axially registered with the collar barrel cutouts  506  to receive the barrels  24 . The suppressor rear panel  513  also includes a center hole  518  for reducing weight. The flash suppressor  26  includes an attachment portion  528  that is adapted for attaching to the tube front end  520 , such as by rivets or other suitable attachment means. Unlike some prior art barrel clamp designs, the barrel clamp assembly of  25  does not require a central support shaft because the barrel clamp tube  502  provides the required strength and stiffness without using such a central support shaft. 
     As can be seen in  FIG. 1A , when the barrels  24  are held within the barrel clamp tube  502 , the flash suppressor forward portion  512  extends forward of the barrel muzzle ends to suppress flashes emitted from the muzzle ends resulting from firing of the minigun. Referring to  FIGS. 4-6 and 10 , the flash suppressor forward portion  512  includes longitudinal slots  514  for reducing the flash associated with a muzzle blast. In operation, when the minigun  10  is fired, a bullet  83  exiting the muzzle travels along the longitudinal axis of the barrel  24  through the interior of the flash suppressor forward portion  512 . Following the bullet, the hot, high pressure gases of the muzzle blast enter the suppressor forward portion  512 . As they do so, they begin to expand outwardly through the slots  514  into the surrounding ambient air and are cooled, which reduces the flash associated with muzzle blast. In some embodiments, such as the embodiment of  FIG. 10 , the slots  514  have diverging sidewalls  530 , which can permit the muzzle blast gases to expand more fully before reaching the surrounding ambient air, and can further reduce the flash from the muzzle blast. 
     Referring to  FIGS. 4-9 , the impeller  504  is an open impeller (i.e., the impeller blades  508  are not covered) and is mounted within the barrel clamp tube  502  midway between the barrel clamp collar  505  and the flash suppressor  26 . The impeller  504  has a ring-like body of one-piece construction and includes a peripheral rim portion  507  and attachment portion  505  that is adapted for attaching to the barrel clamp tube  502 , such as by rivets or other suitable attachment means. A rear flange portion  511  projects inwardly and perpendicular to the longitudinal main axis D. The rear flange portion  511  defines six barrel cutouts  510  for receiving the barrels  24  and holding them parallel to the longitudinal main axis D. A plurality of curved impeller blades  508  are equally spaced around the periphery of the impeller  504  and project forward from the rear flange portion  511 . The blades  508  are curved inwardly toward the longitudinal main axis D and define a plurality of channels  532 , each of which is between two of the blades  508 . In the embodiment of the impeller  504  shown in  FIGS. 4-10 , for example, the impeller  504  has six impeller blades  508  which define six channels  532 . 
     As shown in  FIG. 7 , when the barrel assembly  12  is assembled, the collar barrel cutouts  506 , impeller barrel cutouts  510  and flash suppressor barrel apertures  516  are axially registered with each other to receive the barrels  24 . 
     In operation, the impeller  504  rotates with the barrel clamp tube  502  as the barrel assembly  12  and the barrel clamp assembly  25  rotate. Thus, when the minigun  10  is firing and the drive motor  14  is causing the barrel assembly  12  to rotate, the impeller  504  is also rotating. During this rotation, the impeller  504  moves surrounding ambient air through the tube longitudinal openings  503  and over the portion of the barrels  24  within the barrel clamp tube  502 , thereby cooling the barrels  24 . In addition to allowing for air flow, the longitudinal openings  503  advantageously reduce the weight of the barrel clamp tube  502 . 
     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.