Patent Publication Number: US-7581484-B1

Title: Weapon system retention device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit under 35 USC 119(e) of U.S. provisional patent application 60/595,974 filed on Aug. 22, 2005, which is hereby incorporated by reference. 

   STATEMENT OF GOVERNMENT INTEREST 
   The inventions described herein may be manufactured, used and licensed by or for the U.S. Government for U.S. Government purposes. 

   BACKGROUND OF THE INVENTION 
   The invention relates in general to weapon systems and in particular to a retention device for positioning propellant and/or ammunition in guns. 
   The problem of how to hold munitions in an open cannon chamber has existed for as long as cannons have been used. A common method is to de-elevate the cannon to a horizontal position between firings. This method drastically reduces the number of rounds fired per minute because of the time needed to reposition the cannon for firing. Another method used to hold propellant in an elevated chamber is the Swiss notch. The Swiss notch is basically a notch cut into the chamber of the cannon at the six o&#39;clock position. The notch is designed so that propellant bags or charge modules will catch on the notch if they begin to fall out of the chamber due to gravity. The Swiss notch is only somewhat effective because it is totally dependent on the drop angle, weight, and profile of the propellant bag or module to fall uncontrolled into the notch. At higher angles, the propellant bag or module may not fall into the notch. In addition, experience has shown that the Swiss notch is not a foolproof method to keep the propellant bag or charge modules from falling out of the chamber at any elevated angle. Further, the combustion debris may fill the notch and render it useless. 
   In a breech-loaded cannon, it is most efficient to load propellant bags or charge modules using a device such as an automatic loader. Typically, the propellant bags or modules are loaded with the cannon muzzle at an elevated angle. However, upon withdrawal of the auto-loader ram, the propellant can fall out of the chamber due to the elevated muzzle. 
   SUMMARY OF THE INVENTION 
   It is an object of the invention to provide a device to hold propellant inside a firing chamber until the breech is closed. 
   It is another object of the invention to provide a device to hold propellant inside a firing chamber without having to lower the muzzle, load the cannon and then reposition the muzzle. 
   It is a further object of the invention to provide a device to hold propellant inside a firing chamber wherein the device operates automatically. 
   One aspect of the invention is an apparatus for retaining an object in a gun tube of a weapon system, the gun tube having a longitudinal axis, a chamber and a breech ring with an opening therein, the apparatus comprising a plunger that reciprocates in the opening in the breech ring and the chamber; a housing fixed in the opening in the breech ring, the housing holding the plunger; and means for reciprocating the plunger in the opening in the breech ring and the chamber. 
   In one embodiment, the weapon system includes a non-recoil surface and the means for reciprocating the plunger includes a compression spring disposed around the plunger and a solenoid fixed to the non-recoil surface such that, when activated, the solenoid is operable to move the plunger into the chamber and, when deactivated, the compression spring moves the plunger out of the chamber. 
   In a second embodiment, the weapon system includes a breech crankshaft and the means for reciprocating the plunger includes a drive gear attached to the breech crankshaft; a fixed shaft having a driven gear mounted thereon that meshes with the drive gear; a cam mounted on the fixed shaft and including a cam path; and a cam follower fixed to the plunger and operable to follow the cam path of the cam. 
   In a third embodiment, the weapon system includes a breech crankshaft and the means for reciprocating the plunger includes a cam mounted on the breech crankshaft and including a cam path; a cam lever having one end rotatably attached to the housing and another end with an opening formed therein; a first cam follower fixed to the plunger and disposed in the opening in the cam lever; and a second cam follower mounted on the cam lever and operable to follow the cam path of the cam. 
   Another aspect of the invention is a method of retaining an object in a gun tube of a weapon system, the gun tube having a longitudinal axis, a chamber and a breech ring with an opening therein, the method comprising placing the object in the gun tube; and moving a plunger through the opening in the breech ring and into the chamber such that a portion of the plunger contacts a rear surface of the object. 
   The invention will be better understood, and further objects, features, and advantages thereof will become more apparent from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings, which are not necessarily to scale, like or corresponding parts are denoted by like or corresponding reference numerals. 
       FIGS. 1A and 1B  are sectional, schematic views of one embodiment of the invention in a deactivated and an activated mode, respectively. 
       FIGS. 2A and 2B  are exploded and assembled perspective views, respectively, of the embodiment of  FIGS. 1A and 1B . 
       FIG. 3  is a view of one end of a plunger. 
       FIGS. 4A and 4B  are sectional views of a second embodiment of the invention in a deactivated and an activated mode, respectively. 
       FIG. 5  is an exploded view of the second embodiment. 
       FIG. 6A  shows a housing and drive gear assembly of the second embodiment. 
       FIG. 6B  shows the driven gear and fixed shaft assembly of the second embodiment. 
       FIG. 6C  shows the cam assembly of the second embodiment. 
       FIG. 7  is an exploded view of the housing and plunger of the second embodiment. 
       FIGS. 8A-8D  are top, side, interior perspective and exterior perspective views, respectively, of a cam of the second embodiment. 
       FIGS. 9A and 9B  are sectional views of a third embodiment of the invention in a deactivated and an activated mode, respectively. 
       FIGS. 10A and 10B  are exploded, perspective views of the third embodiment. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The invention holds propellant bags or propellant modules inside the firing chamber of a gun until the breech is closed. The cannon is loaded at an elevated muzzle angle without having to lower the muzzle, load the cannon, and reposition the muzzle. Because some loading steps are eliminated, the invention is faster and safer than known methods. A paddle-like retaining device is introduced at the firing chamber entrance to hold the propellant in place. The retaining device may be mechanically, electrically and/or hydraulically inserted into the firing chamber. 
   In some embodiments, the retaining device is activated during the mechanical action of opening and closing the breech by using an electrically operated solenoid, hydraulic actuator or cam action. During firing, the retaining device is in the retracted position away from the chamber opening. After firing, the breech is opened and the projectile and propellant modules are loaded into the chamber for the next round. When the propellant modules have been placed into the firing chamber, the load ram is extracted and the retaining device is actuated. The retaining device may extend through a port in the breech ring and thence into the chamber access area to hold the propellant in place. The retaining device may be actuated in various ways. 
     FIGS. 1A and 1B  are sectional, schematic views of one embodiment of the invention in a deactivated and an activated mode, respectively. In  FIGS. 1A and 1B , the view is from the breech end of the gun tube  14  looking forward. Apparatus  10  functions to retain an object  12  in the chamber  19  of a gun tube  14  of a weapon system  16 . The gun tube  14  has a longitudinal axis X and a breech ring  18  with an opening  20  therein. The apparatus  10  includes a plunger  22  that reciprocates in the breech ring  18  and the chamber  19 , and a housing  24  fixed in the opening  20  in the breech ring  18 . Housing  24  holds the plunger  22 . Apparatus  10  further includes a means for reciprocating the plunger  22  in the breech ring  18 . 
   In  FIGS. 1A and 1B , the object  12  to be retained or positioned in the gun tube  14  is typically propellant, such as a bag or charge module. To effectively retain the object  12  in the tube  14  against the force of gravity, the end of the plunger  22  that contacts the object  12  may include an increased area portion  28 , as shown in  FIG. 3 . The increased area portion  28  contacts the rear end of the object  12  and prevents the object  12  from sliding rearward to the breech of the gun tube  14 . 
   The weapon system  16  includes a non-recoil surface  30 . In the embodiment of  FIGS. 1-2 , the means for reciprocating the plunger  22  includes a compression spring  32  disposed around the plunger  22  and a solenoid  34  fixed to the non-recoil surface  30 . When activated, as in  FIG. 1B , the solenoid  34  is operable to move the plunger  22  into the gun chamber  19 . When deactivated, as in  FIG. 1A , the compression spring  32  moves the plunger  22  out of the gun chamber  19 . The weapon system  16  includes a fire control system  36  shown schematically in  FIGS. 1A and 1B  as a box. The fire control system  36  is connected to the solenoid  34  via wire  35 , for activating and deactivating the solenoid  34 . 
   The solenoid  34  is actuated after the propellant is loaded into the gun tube  14 , causing the plunger  22  to extend into the breech chamber  19  behind the propellant, thereby holding the propellant  12  in place. Just prior to full closure of the breech, the solenoid  34  is deactivated and the plunger  22  is retracted. Plunger  22  remains retracted until the weapon system  16  has fired, the breech is reopened and a new charge is loaded into the gun tube. As best seen in  FIG. 1B , a vertical plane V through tube  14  intersects a longitudinal axis A of plunger  22  forming an angle alpha. In one embodiment, it is preferred that alpha is about thirty-eight degrees. Of course, other angles may be used. 
     FIGS. 2A and 2B  are exploded and assembled perspective views, respectively, of the apparatus  10  of  FIGS. 1A and 1B . In  FIG. 2A , the view is from the front of the gun tube looking rearward toward the breech. In  FIG. 2B , the view is an angled view from the front looking rearward.  FIGS. 2A and 2B  do not show the solenoid  34 , the non-recoil surface  30  or the fire control system  36 . 
   As best seen in  FIGS. 2A and 2B , apparatus  10  includes an indicator tab  38  inserted in a hole  39  in plunger  22 . Indicator tab  38  moves up and down in slot  37  of housing  24  with plunger  22 . Thus, indicator tab  38  may be used as a check on the position of plunger  22 . For example, indicator tab  38  may comprise a magnetic material and a magnetic sensor may be mounted adjacent housing  24  to sense the position of indicator tab  38 . The magnetic sensor may be connected to the fire control system  36  ( FIGS. 1A and 1B ) such that an incorrect position of plunger  22  stops the operation of weapon system  16 . 
     FIGS. 4A and 4B  are sectional, schematic views of a second embodiment of the invention in a deactivated and an activated mode, respectively. In  FIGS. 4A and 4B , the view is from the breech end of the gun tube looking forward. The apparatus  40  functions to retain an object  12  in the chamber  19  of a gun tube  14  of a weapon system  16 . The gun tube  14  has a longitudinal axis X and a breech ring  18  with an opening  20  therein. The apparatus  40  includes a plunger  42  that reciprocates in the breech ring  18  and chamber  19 , and a housing  44  fixed in the opening  20  in the breech ring  18 . Housing  44  holds the plunger  42 . Apparatus  40  further includes a means for reciprocating the plunger  42  in the gun breech ring  18  and chamber  19 . 
   Weapon system  16  includes a breech crankshaft (not shown) that fits through lug  46 . The means for reciprocating the plunger  42  includes a drive gear  48  attached to the breech crankshaft; a driven gear  52  that meshes with and is driven by the drive gear  48 , the driven gear  52  being rotatably mounted on a fixed shaft  50 ; a cam  54  mounted on the fixed shaft  50  and including a cam path  56  ( FIG. 5 ); and a cam follower  58  fixed to the plunger  42  and operable to follow the cam path  56  ( FIG. 5 ) of the cam  54 . As shown in  FIG. 5 , the cam  54  comprises a generally conical shape and includes the cam path  56  on an external surface thereof. 
     FIG. 5  is an exploded view of the second embodiment, viewed from the front of the gun tube looking rearward. Both the drive gear  48  and the fixed shaft  50  have been shifted to the right in  FIG. 5 . One end of the driven gear  52  includes a flange  60  that mates with a recess  74  ( FIG. 8C ) in the interior of cam  54  to drive the cam  54 . As shown in  FIG. 4B , an angle beta between a longitudinal axis M of the plunger  42  and an axis of rotation N of the fixed shaft  50  is an acute angle. Preferably, the angle beta is about 45 degrees. Details of apparatus  40  are further seen in the perspective views of  FIGS. 6A-6C . 
     FIG. 6A  shows the housing  44  and plunger  42  lifted away from breech ring  18  to show the opening  20  in breech ring  18 . The drive gear  48  is shown removed from breech lug  46 . The breech crankshaft (not shown) engages drive gear  48  on the opposite side of breech lug  46 . The driven gear  52 , fixed shaft  50  and cam  54  are not shown in  FIG. 6A . FIG.  6 B shows the driven gear  52  and the fixed shaft  50 . Drive gear  48  ( FIG. 6A ) drives driven gear  52  thereby rotating the flange  60 . Flange  60  engages the interior  74  ( FIG. 8C ) of cam  54  and drives cam  54 . Drive gear  48  ( FIG. 6A ) is supported in opening  62  in breech lug  46  and fixed shaft  50  is supported in a second opening  64  in lug  46 .  FIG. 6C  shows the cam  54  assembled to the fixed shaft  50  (located inside of cam  54 ). 
     FIG. 7  is an exploded view of housing  44  and plunger  42 . Plunger  42  is formed in two parts with ribs or teeth  70  that mesh together in housing  44 . Plate  66  secures plunger  42  in housing  44 . The lower end of plunger  42  includes the portion  68  that contacts the object in the chamber  19 . The portion  68  is generally widened to increase the area of contact and may be bent as needed. 
     FIGS. 8A-8D  are top, side, interior and perspective views, respectively, of cam  54  showing three-dimensional cam path  56 . Cutouts  72  reduce the weight of cam  54 . Flange  60  ( FIG. 6B ) of fixed shaft  50  ( FIG. 6B ) engages cam  54  in its interior at  74  ( FIG. 8C ). 
     FIGS. 9A and 9B  are sectional views of a third embodiment of the invention in a deactivated and an activated mode, respectively. In  FIGS. 9A and 9B , the view is from the rear of the gun looking forward.  FIGS. 10A and 10B  are exploded, perspective views of the third embodiment. The third embodiment is an apparatus  80  that functions to retain an object  12  in a chamber  19  of a gun tube  14  of a weapon system  16 . The gun tube  14  has a longitudinal axis X and a breech ring  18  with an opening  20  therein. The apparatus  80  includes a plunger  82  that reciprocates in the breech ring  18  and the chamber  19 , and a housing  84  fixed in the opening  20  in the breech ring  18 . Housing  84  holds the plunger  82 . Apparatus  80  further includes a means for reciprocating the plunger  82  in the breech ring  18 . 
   Weapon system  16  includes a breech crankshaft  86  that fits through breech ring lugs  46 . The means for reciprocating the plunger  82  includes a cam  88  mounted on the breech crankshaft  86  and rotated by the carrier (not shown). Cam  88  is generally disc shaped and includes a cam path  90  ( FIG. 10B ) formed on one side. A cam lever  92  ( FIG. 10A ) has one end rotatably attached to the housing  84  using cam lever shaft  98 . Torsion spring  100  provides a biasing force to the cam lever  92 . 
   The other end of cam lever  92  includes an opening  130  therein. Cam follower  96  is fixed to the plunger  82  ( FIGS. 9A and 9B ) with cam shaft  120 . Cam follower  96  rides in opening  130  in cam lever  92  and moves the plunger  82  up and down as the cam lever  92  rotates about cam lever shaft  98 . Cam follower  94  is connected to the cam lever  92  with cam shaft  118  and rides in cam path  90  ( FIG. 10B ). As shown in  FIG. 9A , an angle delta between the longitudinal axis S of the plunger  82  and an axis of rotation T of the breech crankshaft  86  is about ninety degrees. 
   Further details of the assembly of apparatus  80  are seen in  FIGS. 10A and 10B . Plunger  82  ( FIG. 9A ) comprises a split rod with an upper portion  102  and a lower portion  104 . Housing cover plate  106  confines plunger  82  ( FIG. 9A ) in housing  84 . A steel plug  108  functions as a target for proximity sensors (not shown) that are placed in the top and bottom of the housing cover plate  106 . As the upper portion  102  of the plunger  82  moves up and down, the proximity sensors (not shown) in the housing cover plate  106  sense the presence or absence of the steel plug  108  and thereby provide an indication of the location of plunger  82 , that is, activated ( FIG. 9B ) or deactivated ( FIG. 9A ). Cam lever shaft  98  is provided with a bushing  110  and spring pin  112 . A housing plate washer  114  and bolts  116  are used to attach housing cover plate  106  to housing  84 . Cam followers  94 ,  96  ride on cam follower shafts  118 ,  120 . 
   While the invention has been described with reference to certain preferred embodiments, numerous changes, alterations and modifications to the described embodiments are possible without departing from the spirit and scope of the invention as defined in the appended claims, and equivalents thereof.