Abstract:
An automatic primer feed mechanism for use with a carrier assembly of a large caliber artillery piece, which includes mechanical assemblies for automatic primer loading after full breech closure and allows for spent primer cartridges to be extracted before opening of the breech to maximize safety, thereby allowing the gun crew to perform artillery piece misfire, sticker and check fire operations before the breech is opened. The mechanism includes a body member that mounts the automatic feed mechanism to the carrier of the artillery piece so as to interface with the carrier to position the mechanism on one side of the breech of the artillery piece. The body member includes a cam surface member, which provides a path for movement of an injection arm member. The tray member has guide rails for engagement with the body, which slides in relation thereto. A magazine containing a plurality of primer cartridges, which inserts in a receiver channel located in the tray member. The mechanism provides improved safety wherein live primers stored in a magazine are at a distance from the firing chamber hole that prevents flame from reaching a live charge before a fresh primer is injected therein.

Description:
RELATED APPLICATIONS 
   This application claims benefit of filing date Nov. 15, 2000 based upon patent application of Stephen M. Van Dyke-Restifo, Ser. No. 09/718,106, now abandoned entitled “Automatic Primer Feed Mechanism”, and also the filing date of Sep. 6, 2000 based upon provisional application of Stephen M. Van Dyke-Restifo et al., Ser. No. 60/230,450 and also entitled “Automatic Primer Feed Mechanism,” which are hereby incorporated by reference. 

   STATEMENT OF GOVERNMENT INTEREST 
   The invention described herein may be manufactured and used by or for the United States Government for Governmental purposes without the payment of any royalties thereon. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates generally to artillery systems and, more particularly to a system for automatically feeding primer cartridges in an artillery piece. 
   2. Description of the Prior Art 
   Present field artillery pieces operate by detonating a propellant charge behind a projectile in a gun barrel. Typically the propellant charge is detonated by means of a primer cartridge that, in turn, is detonated under the force of an externally applied blow or electrical current. A fresh (unfired) primer cartridge must be used for each firing of the artillery piece. 
   The technical advancement of heavy armored/mechanized weapons and the necessity of providing responsive, effective fires throughout the supported commander&#39;s area of influence has created a need for enhanced rate of fire and reduced labor intensiveness of the crew. Presently, for large caliber artillery pieces with interrupted screw block breech mechanisms such as 155-mm artillery pieces and the like, percussion primers are loaded by hand and various types of automatic feed mechanisms. One primer is typically manually placed in the spindle primer chamber and the firing mechanism is thereafter manually moved over the primer in the ready-to-fire position. This has lead naturally to human errors, injury and problems inserting the primer, especially when the light is dim. Lack of space and/or coordination are additional artillery piece problems associated with hand loading. 
   Until the present invention, there has not been effective fail-safe alternatives to manual loading of primers. There is need for a primer feed mechanism that automatically feeds live primers and ejects spent primer cases in large caliber artillery pieces (for example a 155-mm gun). Although one known automatic-type primer feed mechanism is taught in U.S. Statutory Invention Registration H-1121 by Carroll et al., which is hereby incorporated by reference, there are problems inherent with this mechanism that include potential accidental misfiring of a primer cartridge before proper closing of the breech, which in turn may result in accidental human casualty. Thus there is still need for a safe and efficient system for loading primer cartridges in the breech of a gun, which the present invention resolves. 
   OBJECTS AND SUMMARY OF THE INVENTION 
   In view of the foregoing, it is a general object of the present invention to provide a new and improved system for feeding primer cartridges in an artillery piece, which includes a means for automatic primer loading after full breech closure and spent primer extraction before breech opening to maximize safety, thus allowing the gun crew to perform gun misfire, sticker and check fire operations before the breech is opened. 
   It is a further object of the present invention to provide a new and improved system for feeding primer cartridges in an artillery piece, wherein the primer cartridges are automatically fed with minimum of handling by operating personnel, thereby saving time during a fire cycle. 
   It is a still further object of the present invention to provide a new and improved system for feeding primers in an artillery piece that is reliable and able to withstand the repeated recoil of the artillery piece as it is fired over and over. The automatic primer feed mechanism of the present invention offers several advantages. For example, loading is simplified because the gun crew need only handle previously loaded magazine assemblies rather than individual primers. 
   Yet another object of the present invention is to provide a device for automatically feeding primers, which reduces the number of required gun crew members. 
   Still another object of the present invention is to provide a device for automatically feeding primer cartridges to large artillery pieces and the like which is safe, dependable, and easy to maintain. 
   The above and other objects of the present invention are accomplished using the invention&#39;s automatic primer feed mechanism. In particular, the present invention provides a new and improved system for feeding primer cartridges in an artillery piece, which includes mechanisms for automatic primer loading after the artillery piece&#39;s breech is closed and spent primer extraction before the breech is opened again. This feature enhances gun crew safety and allows them to perform artillery piece misfire, sticker and check fire operations before the breech is opened. 
   The mechanism includes a body member for mounting the automatic primer feed mechanism to the carrier assembly of the artillery piece so as to position the mechanism on one side of the breech of the artillery piece. The body member also includes a cam surface member for control of motions of a primer injection arm member. The body member has guides that control movements of and retain a tray member. The tray member includes congruent guide rails for engagement with the body member&#39;s guides. A primer extraction member is attached to the body member for extracting spent primers when the tray member is moved to an extraction position of travel. The movement on the tray member is controlled by cooperative action with the injection arm member that is attached through linkages to an actuator attached to the carrier. The mechanism also includes a primer cartridge magazine mounted on the tray member for housing a plurality of primers for insertion into the artillery piece, including a slot in one side to permit the injector arm to cooperatively engage and move primers contained in the magazine upon movement of the injector arm to a ready-to-fire position. The tray member includes an integral receiver for mounting the magazine. Live primer cartridges are stored in the magazine that is attached to the tray. The tray member in turn is attached to the body member and located at a safe distance from the firing chamber within the spindle, thereby preventing flames from reaching a live charge before the primer is injected into the firing chamber. Such a design provides “hands-off” functionality during normal firing operation. The magazine uses a clip-type assembly for holding a plurality of primers. An open tray design allows ease of access to the firing chamber area for manual primer extraction if required. 
   During a fire cycle of operation, recoil motion of the artillery piece disconnects the primer feed mechanism from external actuator drive linkages wherein the tray member remains locked in a fire position during recoil and counter recoil. An external drive linkage of the primer feed mechanism re-engages the system mounted drive actuator on counter-recoil. The extract cycle of a spent primer cartridge is initiated after counter recoil and the extract cycle is completed prior to the breech of the artillery piece being opened. The primer feed mechanism can be manually, hydraulically, or otherwise power actuated from the fire position to the extract position of the mechanism. Spent primer extraction occurs when the tray member motion is at a location that actuates a pivoting extraction arm member that is retained in a cavity of the body member. 
   The operation of the device includes: a) opening the breech wherein breech opening locks the tray member in an extract position; b) load charge and projectile; c) close breech fully; d) inject a fresh primer cartridge wherein the injection arm member is manually, hydraulically or otherwise power actuated causing the tray member to translate from the extract to the fire position, and further causing the tray member&#39;s linear motion to dwell as the injector arm member rotates to inject a fresh primer, and further causing the linear motion of the tray to resume with the injector arm member in a down position, and further causing the mechanism&#39;s tray member to travel to the fire position, and the tray member is locked in a fire position; and e) the tray member is locked in the fire position ready to fire the artillery piece. 
   The mechanism provides improved safety wherein live primers stored in a magazine are at a distance from the firing chamber hole that prevents flame from reaching a live charge before a fresh primer is injected therein. A fresh primer is loaded after full breech closure and extracted before the breech is opened to maximize safety, and allowing a gun crew to perform misfire, sticker, and check fire operations before the breech is opened. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     For a more complete understanding of the invention, reference is hereby made to the drawings, wherein like numbers designate like parts, in which: 
       FIG. 1  is an isometric fragmentary perspective view of the mechanism when the primer is loaded for firing; 
       FIG. 2  is another isometric fragmentary perspective view of the mechanism at a different viewing angle with a primer being extracted; 
       FIGS. 3   a ,  3   b ,  3   c ,  3   d  and  3   e  are views of a tray member, an injector arm member, a body member and a magazine assembly in both built up and broken out views respectively; 
       FIG. 3   f  shows an assembly view of a primer firing mechanism used with the present invention; 
       FIG. 4  is a view of an assembly of the components shown in  FIG. 3 ; 
       FIG. 5  is a side view of the mechanism in a ready to fire position and starting point of the extraction cycle; 
       FIG. 6  is a side view of the primer extraction cycle of the mechanism, breech closed phase; 
       FIG. 7  is a side view of the primer extract cycle phase of the mechanism in a raise injector arm, continue extration cycle, breech closed; 
       FIG. 8  is an side view of the primer extraction cycle phase of the mechanism in an extract fired primer position followed by an open breech phase; 
       FIG. 9  is a side view of the initiation of the primer load/inject cycle phase of the mechanism, breech closed; 
       FIG. 10  is a side view of the primer load inject cycle phase of the mechanism in an initiate injection cycle, breech closed phase; 
       FIG. 11  is a side view of the primer injection load cycle phase of the mechanism in a primer injected cycle where the injector arm rotates to inject the primer, breech closed; and 
       FIG. 12  is a side view of the primer fire cycle phase of the mechanism, primer loaded and in a fire position. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to the drawings, and, in particular, to  FIGS. 1–5 , an automatic primer feed mechanism  20  embodying various features of the invention is shown in exemplary form mounted adjacent to the breech carrier end of an artillery piece. In accordance with conventional practice, the artillery piece includes a breech block (not shown for clarity) mounted to a hinged breech carrier  10  that swings to allow the breech to be opened and closed. The breech block&#39;s interior face includes an obturator that is carried at one end of a spindle extending through the breech block. The obturator and obturator spindle  8  include a central passageway  9  that terminates at one end in a chamber  4  for receiving therein a primer cartridge  26  of known construction. In use, a propellant charge is placed in the gun barrel ahead of the breech block which is then closed. Detonation of the primer cartridge  26  ignites the propellant charge through the passageway  9  to fire the artillery piece. 
   The automatic primer feed mechanism  20  functions broadly to contain a plurality of primers  26 , to automatically and individually insert unfired primers into the chamber  4  and to automatically extract fired primers from the chamber in a safe manner so that the breech closes prior to insertion of the primer. To this end, the automatic primer feed mechanism  20  generally includes a clip-like magazine  28  for containing a plurality of primer cartridges  26 , a mounting assembly formed in a tray  21  for mounting the magazine  28  to the feed mechanism  20 , and a firing mechanism  50  retained in an opening  51 , which is responsive to an operator input for firing the artillery piece. Preferably, the magazine  28  is a detachable unit so as to permit substitution of a magazine containing fresh primers. 
   Referring now to  FIGS. 1 and 2 , the primer feed mechanism  20  is designed for use with the carrier  10  of a large caliber artillery piece (in exemplary form, a 155-mm howitzer). A rack is inserted to the hinged carrier  10  that swings to allow opening and closing of the breech. The automatic primer feed mechanism assembly  20  includes a body member  23 , a tray member  21 , a cam surface channel member  22  that is part of the body member  23  wherein a pin  31  travels, and one or more linkage members  25 ,  27 ,  29  (in exemplary form) that cooperatively connect with an injection arm member  24 , (the end linkage  29  connects with the carrier  10  which in turn has an actuator (not shown) attached to the carrier). One end of the injector arm member  24  travels in the cam surface member  22  by the actuator pin member  31  that is caused to move by the linkages  25 ,  27  and  29  by the carrier actuator. The other end of the injector arm  24  has an attached cylindrical member  24   a  that inserts through the member  29  forming part of the tray member  22  through a slot that in turn can be inserted into the magazine  28  when in a fire mode and act as a safety member. The cylindrical member  24   a  has a slot for accepting the arm member  24  such that the cylindrical member can rotate about pinned attachment member within the member  24   a  and allow translational injection movement of the primer into the firing chamber  4 . Such a feature prevents jamming of the primer as it is injected and also minimizes misfiring of a primer cartridge during the injection operation. Also, the other end of the member  24   a  has a hollow surface so as to engage the primer cartridge outside of the central percussion area of the primer cartridge. In manual operation of the feed mechanism  20 , the linkages  27  and  29  can be removed with ease by the gun crew and be manually operated. Moreover, the magazine  28  and the injection arm member  24  with the cylindrical injector  24   a  can be removed by a gun crew and the feed mechanism  20  can be operated by a handle attached to the tray member  23 . 
   The feed mechanism  20  is attached to the carrier  10  through the body member  23  and the tray member  21  slides on guide rail members attached to the body member. The body  23  is located on one side of the breech of an artillery piece. The body  23  includes a primer extractor member  102  (shown in  FIG. 3   c ) that ejects spent primers during the eject cycle of operation of the primer feed mechanism. An assembled primer feed mechanism  20  as shown in  FIG. 4  has the tray  21  slide into the body member  23  so as to control and constrain movement of the tray. The magazine assembly  28  also inserts and slides within a receiver in the tray. 
     FIGS. 3   a ,  3   b ,  3   c ,  3   d  and  3   e  show views of a tray member, an injector arm member, a body member and a magazine assembly in both built up and broken out views respectively. The tray member  21 , shown in detail in  FIG. 3   a , fits onto the body member  23  along the body way  34  shown in  FIG. 3   a .  FIG. 3   b  shows the injection arm  24  with a cylindrical injection member  24   a  and the linkage with a dowel extended that follows the cam path surface of member  22 . The body  23  has a cam channel member  22  that engages the injection arm  24 , later described that moves the tray  21  through a pin linkage  31  that follows the cam path in the channel member  22 . At the left end of the tray  21  is the firing mechanism  50  as shown in  FIGS. 1 and 2 , wherein a firing pin assembly is located under the firing mechanism. The firing mechanism  50  is typically a spring loaded mechanical firing mechanism that is detachable and inserted in the opening with a firing pin  51  in the tray member as shown in  FIG. 3   a.    
   Construction of the magazine  28  can best be understood by reference to  FIG. 3   e . The magazine comprises a built-up clip retaining structure with end plates  28   a  and  28   b  with an opening  41  in one side for receiving individually the primers  26 . A spring/plate  43  mounted in the base of the magazine structure properly biases and indexes the next available primer for firing. A coiled flat constant tension spring is retained in the plate structure and a terminal end attaches to one end of the magazine  28 . A guide member  49   a  provides proper alignment of a fresh primer during injection. A hand operable pin  47  interfaces with a slot in the side plate of the mechanism for manual operation and proper alignment of the plate  43 . Opening  49  interfaces with the injection arm cylindrical member  24   a  under tray member housing structure  29 . A pair of retention guides  53  along the sides of the magazine provide proper alignment and retention in the receiver portion of the tray  21  when attached to the mechanism  20 . In preferred form, up to ten primers  26  can be stored in the magazine  28 . 
   The invention can use various types of a firing mechanism  50  that include a solenoid-type firing mechanism or a mechanical-type firing mechanism. The preferred firing mechanism is shown in  FIG. 3   f  that shows an assembly view of a mechanical firing mechanism  500 . This mechanism provides improved reliability since the dual cam surfaces of the upper portion of a case assembly mates with a follower member has greater interfacing surface areas, thus minimizing both jamming of the firing mechanism and misfiring. The firing mechanism  500  includes: a hammer member  501 , a cup member  502 , a yoke  503 , multiple ball bearings  504 , multiple helical compression springs  505 ,  506  and  507 , a sleeve member  508 , a case assembly  509  with a special dual cam surface that cooperatively interfaces with a dual cam follower member  510 , a pin member  511 , and a pull lever  512 . When assembled, the mechanism  500  is held together under compression by the pin  511  through a hole in the lever  512 . The hammer member  501  is held in place within the yoke  503  by the ball bearings  504 . 
   In operation, the mechanism  500  is actuated and ready to fire an artillery piece by pulling or twisting the lever  512  which causes either direct pulling of the lever member and pulling back on the hammer or cause the interfacing dual cam surfaces of the case assembly  509  and the follower  510  to rotate such that the follower  510  is distended outwards from the case assembly  509 . Once the lever  512  is released, the follower snaps back towards the case assembly  509  which in turn releases the yoke  503  containing the hammer piece  501 , with consequential detonation of a fresh primer cartridge in the firing chamber.
     OPERATION OF THE INVENTION: Operation of the primer feed mechanism  20  can best be understood by reference to  FIGS. 5–12 . The operational phases of the mechanism include: a) firing of the artillery piece, b) recoil/counter-recoil of the artillery piece, c) ejection of the spent primer cartridge, d) opening the breech, e) loading ammunition into the artillery piece, f) close the breech, g) load a fresh primer into the firing chamber of the breech, and h) ready to fire the artillery piece again. As illustrated, the operation of the mechanism  20  can be referred to as a primer load cycle and a primer eject cycle wherein the breach is closed in  FIGS. 5 ,  6 ,  7  and  10 ,  11  and  12 . The breech is opened in  FIG. 8 , and subsequently closed in  FIG. 9  after loading ammunition. The arrows in  FIGS. 5–12  adjacent to the linkages and arms  24 ,  25 ,  27  indicate operational dynamics of the mechanism.   

   In  FIG. 5 , an initial condition is firing of the artillery piece wherein the breech is closed and fresh ammunition is in the artillery piece, fresh primer is in the firing chamber, the tray member  21  is locked to the body member  23  with a tray/body lock. The tray is locked with the firing mechanism  50  over the firing chamber  4  with the fresh primer within. The injector arm  24  is down and inside the magazine  28 . The artillery piece system mounted power actuator is engaged with the feed mechanism  20  externally mounted actuator drive, which is mounted to the carrier that transmits motion to the injector linkages and ultimately the injection arm  24  through a cross-shaft in the carrier. The artillery piece is fired by actuation of the firing mechanism  50  causing the primer to detonate and igniting the main propellant charge and then causing the ammunition to fire. After firing, recoil motion of the artillery piece disengages the system mounted powered actuator from external actuator drive to the mechanism  20 . The tray member  21  remains locked to the body member  23  through the tray/body lock. Then on counter-recoil of the artillery piece, the system actuator engages the external drive linkages to the feed mechanism  20  and the tray member  21  remains locked to the body member  23  through the tray/body locked. 
   Next, initiation of the primer eject cycle as shown in  FIG. 6  begins wherein the breech is still closed. The system mounted actuator applies load to the feed mechanism  20  through the linkages  25  and  27  through the pin  31  that connects to injection arm  24  to unlock the tray/body lock member and allow the tray  21  to move. Continued application of load to the injector arm  24  communicates linear motion to the tray member through the cam surface member  22 . 
   Next, as shown in  FIG. 7 , with the breech still closed, the primer eject cycle of the mechanism continues where continued loading of the injector arm  24  occurs causing it to rotate and rise out of the magazine  28  while linear translation of the tray member  21  dwells. The next fresh primer is indexed in the magazine. Continued loading of the injection arm  24  causes the tray to then resume linear translation towards a full extract position of travel within the body member  23 . 
   In  FIG. 8 , the spent primer is extracted as the tray member  21  actuates the extractor arm member  102  in the body member  23  during terminal travel of the tray by rotating the member  102 . The tray member is then in a full extract position. The breech can then be opened and fresh ammunition can be loaded into the artillery piece. Opening of the breech engages a carrier mounted safety latch that latches the tray  21  in a full extract position as shown in  FIG. 9 . In this condition, the tray and the feed mechanism  20  cannot be accidentally moved to load a fresh primer when the breech is open. A fresh projectile and propellant charge can then be loaded into the artillery piece and the breech closed. After complete closure of the breech, the carrier mounted safety latch is then released and the primer injection cycle begins where the load can again be applied to the injection arm  24 . 
   In  FIG. 10 , the primer loading cycle shows a fresh primer, indexed to be in-line with the injection port  49  of the magazine  28 , wherein the tray  21  dwells as the injection arm  24  rotates by the interactions of cam surface member  22  causing injection of a fresh primer into the firing chamber  4  as the tray motion dwells. 
   In  FIG. 11 , the linear motion of the tray member  21  resumes with the injector arm  24  and member  24   a  injecting the primer into the firing chamber by downward translational motion of the injection member  24   a  within the tray housing  29  until the primer is loaded into the firing chamber. 
   In  FIG. 12 , the tray translational motion continues to the end of travel and the firing mechanism  50  is positioned over the fresh primer. The injection member  24   a  is positioned in the magazine through the opening  49 . Termination of tray motion causes the tray/body lock to re-engage, locking the tray  21  to the body member  23  in a fire position. The primer feed mechanism  20  is in firing position again as in  FIG. 5  and the artillery piece is ready to fire again. 
   While particular embodiments of the present invention have been illustrated and described herein, it is not intended that these illustrations and descriptions limit the invention. Changes and modifications may be made herein without departing from the scope and spirit of the following claims. For example, the primer feed mechanism can be readily adapted for use with a variety of existing artillery pieces. Moreover, the invention can be used in non-military application where a machine requires an automatic injection mechanism that allows injection of a cartridge into a chamber during operation of the machine and precludes need for opening of an object attached to the injection chamber, thereby affording continuous safe operations of the machine. Therefore to be understood, that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.