Abstract:
A primer adapter allows hand grenade fuzes of different configurations to use the same primer for the ignition of their explosive trains.

Description:
UNITED STATES GOVERNMENT INTEREST 
     The inventions described herein may be manufactured, used and licensed by or for the U.S. Government for U.S. Government purposes. 
    
    
     FIELD OF THE DISCLOSURE 
     This disclosure relates to hand grenades. More particularly, this disclosure relates to primers used in hand grenade fuzes. 
     BACKGROUND OF THE DISCLOSURE 
     Hand grenades are small explosive, incendiary, or smoke producing devices thrown by military or law enforcement personnel in the course of military or law enforcement operations. Hand grenades typically have a body that contains an explosive or chemical filler and a fuze that ignites or detonates the filler in the grenade. The fuze contains a powder train that provides a time delay between the arming of the grenade by a soldier or policeman and the actual detonation of the grenade. The fuze is lit by the action of a spring loaded striker mechanism impacting a primer which ignites a delay element that burns for a predetermined time and then detonates the filler. The grenade is prevented from being armed by a safety handle that blocks the striker mechanism from impacting the primer from a primer. A safety pin locks the safety handle to prevent the arming of the grenade. When the safety pin is withdrawn, the safety lever is free to release from the body of the grenade. When the safety lever is released, the striker spring unwinds and the striker rotates on axis to impact the primer, which then creates a flash of heat that ignites one end of the delay element. The delay element burns down to an igniter at the other end of delay element, which then sets off the main charge or filler of the grenade. 
     The M201A1 hand grenade fuze had been in use since World War II, mainly in smoke grenades and the like. Variations of the M201A1 fuze are also used in smoke pots, less than lethal grenades and some lethal grenades. The M201A1 fuze is a pyrotechnic delay igniting fuze. The fuze is equipped with a steel safety pin and pull ring. To arm the grenade, the safety pin is removed while holding the lever tight to the grenade body. When the lever is released, a spring-loaded striker rotates and impacts a primer. The impact with the primer ignites a delay element, which initiates the igniter. The igniter then activates a smoke mix in the grenade achieving the desired signal and/or screening effect. 
     SUMMARY OF THE DISCLOSURE 
     In the recent past, various different configurations of this fuze have been developed. It would be desirable, however, to standardize the parts used in as many grenades as possible, and the U.S. Army has recently started a program to standardize grenade fuzes as much as possible. One of the components that is desirable to standardize is the primer. The M201A1 normally uses an M39A1 primer which in the last several years has caused some failures during production. It would be desirable to replace the unreliable M39A1 primer with the M42 primer which is currently being used on the M228 and M213 fuzes. This primer is less expensive than the M39A1, and the M42 primer has a better history of reliability based on production testing. The M42 primer, however, does not fit the M201A1 fuze. To use the M42 primer in the M201A1 fuze, an adapter disclosed herein was designed to hold the primer securely in the M201A1 fuze by making its diameter fit the size of the M201A1 cartridge. The primer adapter allows the use of the M42 primer with no changes to the current hardware configuration of the M201A1 fuze. It also gives the M201A1 increased reliability compared to the current configuration with the M39A1 primer. The primer adapter also supports commonality among the active hand grenade fuzes such as the M201A1, M213, and M228, by allowing all active hand grenade fuzes to use the same primer for the ignition of their explosive trains. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1   a  is a partially cut away view of an illustrative hand grenade in accordance with the invention. 
         FIG. 1   b  is a bottom view of the grenade of  FIG. 1   a.    
         FIG. 2   a  is a sectional view of an illustrative grenade fuze in accordance with the prior art in an unactuated state. 
         FIG. 2   b  is a sectional view of the grenade fuze of  FIG. 2   a  after actuation. 
         FIG. 3   a  is sectional view of an illustrative grenade fuze in accordance with this invention in an unactuated state. 
         FIG. 3   b  is a sectional view of the grenade fuze of  FIG. 3   a  after actuation. 
         FIG. 4   a  is a side sectional view of a primer adapter in accordance with the invention. 
         FIG. 4   b  is a top view of the primer adapter of  FIG. 4   a.    
     
    
    
     DETAILED DESCRIPTION 
     The following merely illustrates the principles of the disclosure. It will thus be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the disclosure and are included within its spirit and scope. 
     Furthermore, all examples and conditional language recited herein are principally intended expressly to be only for pedagogical purposes to aid the reader in understanding the principles of the disclosure and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. 
     Moreover, all statements herein reciting principles, aspects, and embodiments of the disclosure, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently-known equivalents as well as equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure. 
     Thus, for example, it will be appreciated by those skilled in the art that the diagrams herein represent conceptual views of illustrative structures embodying the principles of the disclosure. 
       FIGS. 1   a  and  1   b  illustratively show the US Military&#39;s M18 colored smoke grenade  10  used for training and combat situations that uses an M201A1 fuze. The fuze in the grenade  10  advantageously may use a primer adapter in accordance with this invention that would permit the use of a primer that is not normally sized for incorporation into the structure of the M18 grenade. The primer adapter in accordance with this invention reduces costs, enhances reliability, and standardizes the parts used in a wide variety of grenade types. 
       FIGS. 2   a  and  2   b  show a conventional M201A1 fuze in the unactuated and actuated states, respectively. The fuze of  FIGS. 2   a  and  2   b , (PRIOR ART), uses a conventional M39A1 primer that has been found to be unreliable. Its existing primer  22  is shown here as being fully encased in a unit  201  which fits snugly into this fuze.  FIGS. 3   a  and  3   b  show an M201A1 fuze in accordance with this invention in the unactuated and actuated states, respectively. The fuze of  FIGS. 3   a  and  3   b  uses an M42 primer ( 24 ) that has been found to be more reliable and less expensive.  FIGS. 4   a  and  4   b  show various views of an adapter  26  to be now used in this a grenade fuze in accordance with the invention. 
     The grenade  10  shown in  FIGS. 1   a  and  1   b  comprises a cylindrical body  12  made of sheet steel and containing a chemical filler material  14  that produces colored smoke when it is ignited by the operation of an M201A1 igniting fuze  16  screwed into an opening in the top of the grenade body  12 . The fuze  16  ignites a chemical starter material  18  that fills the top of the grenade body  12 , which in turn ignites the filler material  14  in the main compartment of the body  12 . Ignition of the filler material  14  produces an expanding cloud of colored smoke which is expelled from the grenade  10  through a normally taped opening  20  in the bottom of the body  12 , and shown most clearly in  FIG. 1   b.    
     Igniting fuzes like the M201A1 fuze  16  in  FIGS. 1   a  and  1   b  are pyrotechnic delay-igniting fuzes designed for use with a variety of chemical hand grenades. They burn at high temperatures to ignite a chemical filler in the grenade. In addition to the M18 smoke grenades, the M201A1 fuze  16  is also designed for use with the AN-M83HC white smoke grenade and the AN-M14 TH3 incendiary grenade. 
     The fuze  16  provides a time delay between the actuation of the grenade and the ignition of the filler material  14 . In one illustrative embodiment, the time delay element is a powder train requiring 1.2 to 2 seconds to burn to the starting mixture. In all cases, the starting mixture ignites the explosive or pyrotechnic and expels the desired output from the grenade body. 
       FIGS. 2   a  and  2   b  are detail drawings of the M201A1 fuze  16  shown in  FIG. 1   a . The fuze  16  of  FIGS. 2   a  and  2   b  uses an M39A1 primer  22  that is more expensive and less reliable than an M42 primer.  FIGS. 3   a  and  3   b  are detail drawings of the M201A1 fuze using an M42 primer  24  adapted for use in an M201A1 fuze. Normally, an M42 primer does not fit securely in the cartridge of an M201A1 fuze  16 . The fuze  16  in  FIG. 2   b  incorporates an adapter  26  that allows the M42 primer to fit securely in the cartridge  28  of the M201A1 fuze  16 . The adapter  26  is shown in  FIGS. 4   a  and  4   b . Adapter  26  has a first end  205  which identically matches the size and shape of unit  201  and which will now be fit snugly into this M201A1 fuze, and it also has a lip  211  on the adapter&#39;s opposite end to aid in so fitting in  26  into the fuze, and holding  26  in place. Adapter  26  also has a counter-sunk annular cavity  209  in its said opposite end to receive new primer  24  (the M42), and which cavity identically mates to primer  24  both in size and in shape, so as to completely receive such primer  24 . Adapter  26  also has a lower opening hole  207  in the adapter&#39;s first end and reaching all the way to said cavity  209  so as to allow a flash from primer  24  to be able to travel further on below into the remainder of the M201A1 fuze. 
     The grenade  10 , in the example of the invention depicted in  FIGS. 1   a  and  1   b , is a burning-type smoke grenade fitted with an M201A1 igniting fuze  16  which functions with a 1.2 to 2-second delay. Functioning of the fuze  16  ignites a starting mixture  18 , which ignites the filler  14 . 
     The burning of the filler  14  creates sufficient pressure to blow out a tape  21  that normally covers one or more emission holes or gas ports  20  in the body of the grenade. Blow out of the tape  21  over the emission hole  20  allows a chemical agent, such as riot control gas or smoke, produced by the combustion of the filler material  14  in the grenade, to escape from the body  12  of the grenade  10  through the emission hole  20 . 
     The fuze  16  in the grenade  10  includes a pull ring and safety pin  30  inserted through a hole  32 . The safety pin  30  in the hole  32  holds a safety lever  33  against the side of the grenade body  12 . The safety lever  33  in position against the body  12  of the grenade  10  holds a striker  34  away from a primer  24  against the force of a striker spring  36  that urges the striker  34  towards the primer  24 . 
     Removal of the safety pin  30  permits release of the safety lever  33 , which then has to be held against the body  12  of the grenade  10  to prevent detonation. Once the grenade  10  is thrown, the pressure on the safety lever  33  is released, and the striker  34  is forced to rotate on its axis by the striker spring  36 , throwing off the safety lever  33 . The striker  34  then impacts the primer  24  with a force that detonates the primer  24 , which then explodes and ignites one end of a delay element  38 . The delay element  38  burns for the prescribed amount of time and then activates the starter mixture  18 . The activation of the starter mixture  18  acts to either explode or burn the filler substance  14 . 
     At this point, while we have discussed and described the invention using some specific examples, those skilled in the art will recognize that our teachings are not so limited. For example, the fuze adapters may be used with pyrotechnic and/or explosive devices which are modified variants of those explicitly disclosed herein. Accordingly, the invention should be only limited by the scope of the claims attached hereto.