Abstract:
This invention provides a cartridge assembly for military and police training to meet the requirement of practicing vividly while making no harm. The assembly mainly comprises a projectile, a sabot, a C-type ring, and a cartridge case, wherein the projectile is disposed in the recess of the sabot; the sabot is fitted tightly into the case and the C-type ring is disposed in the slot at the bottom of the sabot. Upon a primer being struck to ignite powder, the expanding gas partially outbursts and bleed through an orifice to propel a projectile and the other part of energy is applied to eject the cartridge case. As the cartridge case being pulled back, the elasticity of the C-type ring results into the engagement of the sabot and the cartridge case, so as to achieve the aim of the ballistic cycle of the ammunition.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates to the field of ammunition, more specifically, to non-lethal ammunition used in training and war games that could also be used in automatic and semi-automatic firearms.  
           [0003]    2. Description of the Related Art  
           [0004]    There has long existed the need for firing practice of automatic and semi-automatic firearms. As automatic firearms are used by more and more organizations such as the military and police, the need for an effective practice has grown urgently. The idea practice round for automatic and semi-automatic weapons incorporates the functions of firing a non-lethal projectile to mark the impact point, satisfactorily actuating the automatic ejection of the spent casing, functioning in a standard firearm with a minimum modification, and being relatively inexpensive.  
           [0005]    The primary problem that has existed in using automatic or semi-automatic firearms is the providing of enough “kickback” without raising the muzzle velocity or impact force of the projectile. Usually with practice or non-lethal rounds it is important to maintain lower muzzle velocities and keep weight, and therefore to reduce the inertia of the projectile, at a minimum. However, under such circumstances, usually such rounds have not provided enough back force for automatic ejection mechanism for proper actuation.  
           [0006]    Practice firearms nowadays being used involve those utilizing a laser, CO 2  actuation or blanks. Obviously, the laser type devices are expensive, somewhat cumbersome, and usually are not conventional in operation. CO 2  type practice devices are sometimes actuating a capsule type of cartridge with high-pressurized gas and are usually not conventional in operation. The firing of blanks obviously involves no projectile to mark the point of impact and thus unable to offer the advantage of the conventional firearms during practice.  
           [0007]    However, during the ballistic cycle of ammunition, the operation of conventional automatic and semi-automatic firearms are actuated either by the expansion of propellant gas against a sabot connected to the recoiling bolt or by direct blowback of the cartridge case against the bolt upon expansion of the propellant gas. In these systems, the energy provided to the recoil mechanism is related to that imparted to the projectile. That is, a reduced pressure in the chamber or variations in weight of the projectile will result in variation of the total energy given to the firearm-operating mechanism which, in turn, will affect its cyclic rate or the reliability of its operation. With low-mass projectiles or the type used in training and non-lethal cartridge, the problem is especially severe. Frangible projectiles may not be capable of withstanding high accelerations. The low energy required for launch of these lightweight projectiles may not produce a sufficient reaction or necessitate a high enough chamber pressure to cycle conventional firearm mechanisms. Blank cartridge, that is, a cartridge without a projectile, will not normally be able to automatically cycle ejection without a muzzle adapter to increase the pressure in the system sufficiently to make the mechanism function.  
           [0008]    The above mentioned problem may also be observed in larger caliber guns, such as 40 mm grenade launchers, where a relatively low-velocity projectile with limited capacity to withstand high accelerations, is launched from an automatic gas-operated firearms. To overcome such problems, the “high-low” ballistic system is adopted. Propellant in the “high-low” ballistic system is initially burned in a high-pressure section of a partitioned cartridge case and released through orifices into the side containing the projectile at a rate sufficient to limit the peak pressure or acceleration on the projectile. Such a system is described in U.S. Pat. No. 4,686,905. While such system can provide reduced peak forces available for firearm function, necessitating design compromises in the firearm.  
           [0009]    U.S. Pat. No. 5,359,937 entitled “Reduced Energy Cartridge”, issued to Dittrich on Nov. 1, 1994, disclosed a cartridge for low-mass, frangible projectile which comprises a sabot to propel against an inner shoulder of a chamber. The cartridge has a sabot with an orifice applied to lead the propellant gas from the rear of a sabot to the rear of a projectile in order to eject the projectile under controlled impact force. The wall of the cartridge case has an inwardly extended flange and the bottom of the sabot has an outward step. Upon percussion, the cartridge case is pushed backward opposite the sabot by expansion of propellant gas and the step of the sabot is engaged with the flange of the case to engage the cartridge case together with the sabot, thus enables the spent sabot and the cartridge case to eject together. However, during assembly, because the outer diameter of the step of the sabot is larger than the inner diameter of the flange of the case, the sabot is unable to be inserted into the case directly. Other than extra finishing process, material with good malleability, such as copper is necessary for the cartridge case in order to insert the sabot smoothly into the case during assembling.  
         SUMMARY OF THE INVENTION  
         [0010]    It is the primary object of the present invention to provide a practice cartridge which can launch a low-mass, frangible, non-lethal or low energy projectile and the cartridge can be produced efficiently and the material is not limited to conventional copper material, hence to reduce the production cost.  
           [0011]    It is still another object of the present invention to provide a practice cartridge which can launch a low-mass, frangible, non-lethal or low energy projectile and the cartridge can be used in existing semi-automatic and automatic firearms to maintain their reliability of cycling mechanism in semi-automatic and automatic firearms.  
           [0012]    The above-mentioned objects of the invention are achieved by the provision of a cartridge used in existing firearms, such as semi-automatic and automatic firearms, to launch a low-energy projectile. The cartridge comprises a cartridge case having a rear-end portion and a front-end portion, the front-end portion defining an inner diameter and its inner side-wall having an inclined groove; a primer disposed in the bottom of the cartridge case; a sabot comprising a front-end portion with a greater diameter and a rear-end portion with a smaller diameter, the rear-end portion having a substantially occlude end, wherein the outer diameter of the rear-end portion is substantially the same as the inner diameter of the inner wall of the cartridge case fitted hermetically into the cartridge case forming a hermetic space therein, and the outside of the rear-end portion is provided with a groove. The front-end portion of the sabot may be propelled against the shoulder of the chamber and the rear-end portion has at least an orifice to connect the hermetic space to the front-end portion allowing the propellant gas within the hermetic space bleed to the front-end portion through the orifice. Also a limiting element is disposed in the groove of the sabot. Upon percussion, as the inclined groove of the cartridge case slides towards the limiting element, due to the elasticity, the limiting element returns to its uncompressed state and engages with the inclined groove of the cartridge case, thereby limiting the further movement of the cartridge case relative to the sabot.  
           [0013]    According to the cartridge of the present invention, during assembly, the limiting element disposed in the groove of the sabot is fitted into the cartridge case. As the limiting element passes through the inclined groove in the cartridge case, it extends into the inclined groove due to the elasticity. However, as the inclined groove has an inwardly inclined surface, the limiting element can be compressed into the groove by the inclined surface. Thus the sabot can further enter into the cartridge case until the step of the sabot is propelled against the cartridge case. Therefore, the cartridge of the invention can overcome the limitation on manufacture and materials described on U.S. Pat. No. 5,359,937.  
           [0014]    Upon percussion, the propellant gas bursts from the hermetic space through the orifice to the rear-end portion of the projectile to eject the projectile. The front-end portion of the sabot is propelled against the shoulder of the chamber, therefore the cartridge case is pushed backward by the expanded gas generated from the powder. As the inclined groove of the cartridge case slides toward the limiting element, due to the elasticity, the limiting element returns to its uncompressed state and engages with the inclined groove of the cartridge case. Thereby it limits the further movement of the cartridge case relative to the sabot to ensure the spent sabot and the cartridge case to be ejected together in order to achieve the aim of cycling the automatic and semi-automatic firearms. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.  
         [0016]    [0016]FIG. 1 is a perspective view of a cartridge in accordance with a first embodiment of the invention;  
         [0017]    [0017]FIG. 2 is an exploded view of a cartridge in accordance with a first embodiment of the invention;  
         [0018]    [0018]FIG. 3 is a cross sectional view of a cartridge in accordance with a first embodiment of the invention;  
         [0019]    [0019]FIG. 4 is a cross sectional view of a cartridge after percussion in accordance with a first embodiment of the invention;  
         [0020]    [0020]FIG. 5 is a cross sectional view of a cartridge in accordance with a second embodiment of the invention;  
         [0021]    [0021]FIG. 6 is a cross sectional view of a cartridge after percussion in accordance with a second embodiment of the invention;  
         [0022]    [0022]FIG. 7 is a cross sectional view of a cartridge in accordance with a third embodiment of the invention; and  
         [0023]    [0023]FIG. 8 is a cross sectional view of a cartridge after percussion in accordance with a third embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0024]    A first embodiment of a cartridge  10  in accordance with the present invention is depicted generally in FIGS. 1 and 2. The cartridge  10  can be used in conventional firearms, such as semi-automatic and automatic firearms. The cartridge  10  mainly comprises a cartridge case  21 , a sabot  11  disposed in the cartridge case  21 , and a projectile  30  fitted tightly within the front-end portion of the sabot  11 . A limiting element  31 , which is preferable a C-type ring, is disposed between the cartridge case  21  and the sabot  11  of the cartridge  10 .  
         [0025]    [0025]FIG. 3 illustrates the cross sectional view of the cartridge  10 . The cartridge case  21  is a substantially hollow cylindrical body having a primer  26  disposed at the bottom of the cartridge case  21  which provides ignition and/or propulsion energy. A flange  24  at the end of the cartridge case  21  is used to engage with a recoil mechanism to eject the cartridge  10  after percussion. An annular inclined groove  22  is formed at the inner wall of the front-end portion of the cartridge case  21 .  
         [0026]    The sabot  11  of the cartridge  10  has a front-end portion  13  with a larger diameter and a rear-end portion  15  with a smaller diameter, between which a step  18  is formed. The bottom of the rear-end portion  15  with a smaller diameter is substantially closed; its outer diameter is substantially the same as the inner diameter of the cartridge  21  to be fitted tightly into the hollow cylindrical inner wall of the cartridge  21 . A groove  12  is formed on the outer wall of the rear-end portion  15  of the sabot  11 . After the sabot  11  is inserted to the cartridge case  21 , a hermetic space  33  for loading powder  34  is formed between the rear-end portion  15  of the sabot  11  and the bottom of the cartridge case  21 . The outer diameter of the front-end portion  13  is substantially the same as the outer diameter of cartridge case  21 . The front-end portion  13  comprises a recess  14  for receiving a projectile  30 . The rear-end portion  15  of the sabot  11  has at least an orifice  16  to connect the hermetic space  33  to the rear of the projectile  30  allowing the propellant gas within the hermetic space  33  bleed to the projectile  30  through the orifice  16 .  
         [0027]    As the cartridge  10  of the present invention is assembled, the limiting element  31 , preferably a C-type ring, is disposed in the groove  12  of the sabot  11  and corporately fitted into the cartridge case  21 . As the limiting element  31  passes through the inclined groove  22  of the cartridge case  21 , it expands outwards and slides into the inclined groove  22  due to the elasticity. However, as the inclined groove  22  has an inwardly inclined surface, the limiting element  31  can be compressed into the groove  12  by the inclined surface. Thus, the sabot  11  can further enter into the cartridge case  21  until the step  18  of the sabot  11  is propelled against the cartridge case  21 .  
         [0028]    The cartridge  10  may be stored for a long duration after manufacture. The inner wall of the cartridge case  21  preferably has a slot  28  corresponding to the limiting element  31 . When the sabot  11  is tightly fitted in the cartridge case  21 , the limiting element  31  may expand slightly to fit into the slot  28  to preserve its elasticity. After long-term storage, the limiting element  31  of the cartridge  10  will not lose its elasticity caused by long-term elastic fatigue so as not to limit the further travel of sabot  11  opposite to the cartridge case  21  after percussion (described thereinafter).  
         [0029]    In FIG. 4, when the cartridge  10  is being operated, i.e., upon the primer  26  being ignited to induce the expansion of the powder  34 , the propellant gas outbursts from the hermetic space  33  through the orifices  16  to the rear-end portion of the projectile  30 , thereby ejecting the projectile  30  (as the arrows point in FIG. 4). The desired energy for ejecting the projectile  30  may be obtained by adjusting the amount and the size of the orifice(s)  16 . The front-end portion  13  of the sabot  11  is propelled against the shoulder (not shown in the drawings) inside the chamber, therefore the cartridge case  21  is moved backward by the expanded gas produced from powder  34 . As the inclined groove  22  of the sabot  21  slides to the limiting element  31 , the compressed limiting element  31  returns to its uncompressed state due to the elasticity and is engaged with the inclined groove  22  of the cartridge case  21 , thereby limiting the further movement of the cartridge  21  relative to the sabot  11 . The front-end of the sabot  11  is propelled against the shoulder of the chamber of automatic or semi-automatic firearms (not shown in drawings) and by the backward movement of the cartridge case  21 , the flange  24  of the cartridge case  21  is engaged with a recoil mechanism. Thus it enables the sabot  11  of the cartridge  10  and the cartridge case  21  to be ejected together to cycle the automatic and semi-automatic firearms.  
         [0030]    As mentioned above, the projectile  30  of the cartridge  10  of the present invention does not effect the cycle of automatic and semi-automatic firearms. Therefore the projectile  30  can be made of multiple materials and made in multiple forms. For example, the projectile  30  may be a hollow plastic capsule with a pre-cracked notch  44  on top surface, which is filled with a marking dye, a tear gas substance or the like. As the projectile  30  hits a target, the projectile  30  may be broken easily from the pre-cracked-notch  44  and release the filled substance to achieve the functions such as marking the impact point. Further, when the cartridge  10  is blank, i.e., the cartridge  10  has no projectile  30 , the propellant gas escapes from a muzzle, producing the flash and noise and reinforcing the effect of the blank. However, it does not influence the cycle of automatic and semi-automatic firearms.  
         [0031]    The cartridge  40  of the second embodiment of the invention is shown in FIG. 5 and FIG. 6. The mechanism of the cartridge  40  is substantially similar to that of the cartridge  10 , wherein like reference numerals refer to like elements. The difference between the cartridge  10  and the cartridge  40  is the construction of the limiting element  41  of the present embodiment.  
         [0032]    According to the cartridge  40  of the present embodiment, the sabot  11  has at least two recesses  12  at the outside of the rear-end portion  15 . A limiting element  41  includes a pin  42  and a compressed spring  43 . The pin  42  and the compressed spring  43  are disposed respectively into the recess of the sabot  11 . When the cartridge of the present invention is assembled, as the pin  42  and compressed spring  43  pass through the inclined groove  22  of the cartridge case  21 , the pin  42  extends into the inclined groove  22  forced by the compressed spring  43 . However, as the inclined groove has an inwardly inclined surface, the pin  42  can be compressed into the groove  12  by the inclined surface. Thus the sabot  11  can further enter into the cartridge case  21  till the sabot  11  is propelled against the cartridge case  21 . The inner wall of the cartridge  21 , preferably, further comprises a slot  28  corresponding to the pin  42 . When the sabot  11  is tightly fitted in the cartridge case  21 , the pin  42  may expand slightly into the slot  28  to preserve the elasticity of the spring  43 .  
         [0033]    In FIG. 6, when the cartridge  40  is being operated, i.e., upon the primer  26  being ignited to induced the expansion of the powder  34 , the propellant gas outbursts from the hermetic space  33  through the orifice  16  to the rear portion of the projectile  30  to eject the projectile  30  (as the arrows point in FIG. 6). The front-end portion  13  of the sabot  11  is propelled against the shoulder (not shown in drawings); therefore, the cartridge case  21  is pushed backward by the expanded gas produced from the powder  34 . As the inclined groove  22  of the sabot  11  slides to the pin  42 , the compressed spring  43  returns to its uncompressed state due to the elasticity and is engaged with the inclined groove  22  of the cartridge case. Therefore, it limits the movement of the cartridge case  21  relative to the sabot  11 . The sabot  11  is propelled against the shoulder inside the chamber of automatic or semi-automatic firearms (not shown in drawings); the flange  24  of the cartridge case  21  is engaged with a recoil mechanism by the backward movement of the cartridge case  21 . Thus it enables to eject the spent sabot  11  of the cartridge and cartridge case  21  together and to cycle the automatic and semi-automatic firearms.  
         [0034]    The cartridge  50  of the third embodiment of the invention is shown in FIGS. 7 and 8. The mechanism of the cartridge  50  is substantially similar to that of the cartridge  10 , wherein like reference numerals refer to like elements.  
         [0035]    The difference between the cartridge  10  and the cartridge  50  is that the inclined groove  72  is disposed at the end of the sabot  61  and the cartridge case  71  comprises a corresponding groove  62 . Similar to the operation of the cartridge  10  of the above-mentioned embodiments, the limiting element  81  is disposed, during manufacture, into the inclined groove  72  of the sabot  61  and compressed, then fitted corporately into the cartridge case  71 , and then expands into the groove  62 . Thus the limiting element  81  is disposed into the groove  62  and compressed by the inclined surface of the inclined groove  72 . Therefore, the sabot  61  further is fitted into the cartridge case  71 . Alternatively, the sabot  61  also may have another slot  78  to contract the limiting element to preserve the elasticity of the limiting element  81  and to limit the movement of the cartridge case  71  relative to the sabot  61  after percussion.  
         [0036]    In FIG. 8, when the cartridge  50  is in operation, i.e., upon the primer  76  ignited to induce the expansion of the powder, the propellant gas outbursts from the hermetic space  83  through the orifice  66  to the rear of the projectile  80  to eject the projectile  80  (as the arrows point in FIG. 8). Further, the cartridge case  71  also is pushed backward by the expanded gas produced from the powder. As the cartridge case  71  and the limiting element  81  slide backward through the inclined groove  72  of the sabot  61 , the limiting element  81  returns to its non-contracted state due to the elasticity and is engaged with the inclined groove  72  of the sabot  61 . Therefore, it limits the further movement of the cartridge case  71  relative to sabot  61 . The sabot  61  is propelled against the shoulder of chamber of automatic or semi-automatic firearms (not shown in drawings); the flange  74  of the cartridge case  71  is engaged with a recoil mechanism by the backward movement of the cartridge case  71 . Thus it enables to eject the spent cartridge  50  to cycle the automatic and semi-automatic firearms. Similarly, in accordance with this embodiment of the present invention, the cartridge  50  also may be in blank form or its projectile  80  may be a hollow plastic capsule with a pre-cracked-notch  84  on top surface, which is filled with a marking dye or the like to achieve the functions such as marking the impact point.  
         [0037]    According to the above illustration, the cartridge case in accordance with the present invention does not need complicate processes for malleablization and deformation, it can be made of materials with less malleability, such as aluminum, iron, plastic material, or composite materials.  
         [0038]    Therefore, the cartridge of the present invention may not only maintain the reliability of firearm-cycling mechanism of automatic and semi-automatic, the cartridge can also be made easily, thus this invention overcomes the limitation on manufacturing and material which is disclosed in U.S. Pat. No. 5,359,937.  
         [0039]    Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.